Conferences

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• *ALE_STRUCTURED_FSI The New S-ALE FSI Solver

  Hao Chen (Ansys Livermore)

  The LS-DYNA® Structured ALE solver is developed in 2015. It is faster and more stable; uses less memory and storage; its input format is cleaner and much less confusing. It has been well received by users studying behavior of fluids, and especially their interaction with structures. During the past two years, the author worked on a new fluid-structure interaction (FSI) package dedicated to be used with S-ALE solver. The objective is to shorten the running time, stop leakage, and make the input deck user friendly. In this paper this new FSI package, together with its keyword -- *ALE_STRUCTURED_FSI is introduced.

• *MAT GAS MIXTURE, a new gas mixture model for airbag applications

  Lars Olovsson - LSTC

  Recent efforts to model fully coupled CFD-airbag processes have motivated the implementation of a gas mixture model in LS-DYNA. The new model, *MAT GAS MIXTURE, allows the mixing of up to eight different gases. It is designed to conserve the total energy of the system. Kinetic energy dissipated in the ALE advection process is automatically transformed into heat. The article serves as a description of the gas mixture model and of the accompanying keyword commands.

• *MAT_4A_MICROMEC – Theory and Application notes

  P. Reithofer, A. Fertschej, B. Hirschmann, B. Jilka, 4a engineering GmbH;, A. Erhart, S. Hartmann, DYNAmore GmbH

  Nowadays a great number of short and long fiber reinforced thermoplastics play a decisive role in the automotive industry to ensure affordable lightweight design and availability in large quantities. As seen in the last German LS-DYNA® Conference 2016, there is a strong industry interest to consider the manufacturing process induced local anisotropy in crash and general dynamic simulations.

• *MAT_PAPER and *MAT_COHESIVE_PAPER: Two New Models for Paperboard Materials

  Jesper Karlsson, Mikael Schill 1 (DYNAmore Nordic), Johan Tryding (Tetra Pak)

  We here present two new material models for the modeling of paperboard materials. The main motivation for the models is to accurately simulate the production of food and beverage containers for the packaging industry. The main material, *MAT_PAPER, is an orthotropic elastoplastic model that supports both solid and shell elements. In conjunction, an elastoplastic cohesive material, *MAT_COHESIVE_PAPER, is introduced to simulate delamination. Simulations of bending and creasing of paperboard using these new materials, performed in collaboration with Tetra Pak, has shown good correlation with experimental results

• 2D to 3D ALE Mapping

  Nicolas Aquelet - Livermore Software Technology Corporation, Mhamed Souli - Laboratoire de Mecanique de Lille

  A 2D MMALE (Multi-Material Arbitrary Lagrange Euler) code was implemented in LS-DYNA®. Like the 3D MMALE already available each 2D computational cycle is divided in two steps. First a multi-material version of the two-dimensional shell formulations solves the physical problem on quadrangle meshes during the Lagrangian step. The 2D shell formulations are plane strain and area-weighted axisymmetric. An advection step adapted to the 2D shell approaches follows to control the mesh motion. 2D ALE data of the last cycle can be mapped on 3D ALE mesh. Data are stored in a file defined on the command line after the prompt “map=”. This file is read for the 3D model with the same command line.

• 3-Dimensional Forming of Thick Plates - A Comparison of Deep Drawing and an Approach of Rolling and Bending within a Single Process

  Manuel Bojahr, Hannes Prommer, Ralf Tschullik, Patrick Kaeding - University of Rostock

  A variety of industries require certain 3-dimensional formed thick plates, for example in shipbuilding for shell plates. Nowadays the production of curved ship plates is mainly based on the experience of the worker and is performed manually. The results are good and sufficient for the heretofore use in industry, taking into account that the number of curved plates with the same geometry is quite small. Moreover thick plates with a variable thickness are used for instance as so called longitudinal profiles for bridge building. Currently the combination of curved plates with variable thickness does not meet a wide range of applications. But it has high potential in future. In modern shipbuilding this kind of plates offers special applications with a broad scope, e.g. reduction of weight. Renewable energies are another huge market in future. Today, wind turbines are mostly made of glass or carbon fiber. The manufacturing process leads to high precision and quality of the final product. Nevertheless, this fabrication method of rotor blades is very cost intensive and its production technology is not the best in terms of recyclability. In addition to its good reusability, the handling of steel is well known and its fabrication is inexpensive. Due to these facts an idea of rotor blades to be produced from steel arose. However, when desiring a huge output of a product with the same geometry a manual approach is inappropriate. A new process should be repeatable and within a certain accuracy. Deep drawing of the product is a natural choice but is not used for thick plates of enlarged sizes until now. This paper presents a comparison of deep drawing and a new approach. The developed process is based on a superposition of flat rolling and 3-dimensional bending. A major advantage of combining these steps is the opportunity to deliver formed plates with a variable thickness. This paper presents numerical simulations of deep drawing and rolling processes. The results are compared in terms of practicability for the production of rotor blades.

• 3D Drawbead Design and Mesh Regeneration in ANSYS FORMING®

  Xiaolong He, Mouhamadou Mansour Mbow, Junyue Zhang, Yi Xiao, Yiquan Tang, Kang Shen, Jinglin Zheng, Xinhai Zhu

  In ANSYS FORMING, we have developed innovative techniques for predicting drawbead forces and generating 3D drawbead geometry to streamline the drawbead design process, which is crucial for controlling material flow in stamping processes. These tools include a drawbead profile generator, a simulator, and a 3D drawbead generator. The profile generator creates custom drawbead profiles based on sectional design parameters, while the simulator estimates restraint and uplift forces through a strip drawing test. The 3D drawbead generator automatically creates 3D drawbead meshes from single or multiple drawbead profiles for both closed and open beads, enabling accurate material flow estimation in 3D high-fidelity stamping simulations. In addition, we introduce an innovative surface mesh regeneration method based on adaptive quadtree refinement to address issues of distorted or skewed initial meshes. This method intelligently refines regions with complex features or high gradients that require higher resolution, while discretizing smoother areas with coarser elements, optimizing computational resources without sacrificing precision. Our approach also preserves original boundaries, ensuring the fidelity of simulation results. These advancements, validated through real-world examples, significantly enhance the design capabilities and modeling performance of ANSYS FORMING in stamping simulations.

• 3D Numerical Simulations of Penetration of Oil-Well Perforator into Concrete Targets

  Qiankun Jin, Zheng Shigui, Gary Ding, Yianjun, Cui Binggui - Beijing Engineering Software Technology Co., Ltd.

  The oil-well perforator and its interaction with concrete targets are simulated with fluid-structure coupling algorithm and the new mesh motion option of the multi-material ALE formulation of LS-DYNA[1] in Version 960. Comparison of the simulation results to the experimental test data has been conducted. The simulation results show good correlation with data in tests and indicate that LS-DYNA can be used as an engineering tool to help in the prediction of perforation depth.

• 4a impetus - efficient evaluation of material cards for non-reinforced and reinforced thermoplastics

  Peter Reithofer, Martin Fritz, Reinhard Hafellner - 4a engineering GmbH

  LS-DYNA© has included plenty of material cards, each of them offering different scalability and complexity to describe the behavior of non- reinforced thermoplastics. The consideration of the strain rate behavior is included in many material cards, e.g. in the well known MAT_PICEWISE_LINEAR_PLASTICITY. More complex material models can also handle varying compression and tension behavior as well as unloading by using damage functions. One of the recent development results is MAT-SAMP-1 by Du Bois, Kolling, Feucht and Haufe. This specially developed material model for polymers includes a yield surface out of different loading cases and a damage function for better description of unloading. For better use of the above mentioned models a huge amount of tests have to be carried out, to determine the material parameters and to represent the thermoplastic characteristics in crashworthiness simulations. 4a impetus builds up an efficient and reliable process, starting with realistic tests and finally ending up with a validated material card. Recent developments of new test methods for 4a Impetus are presented, that satisfy the needs of complex material models as well as the expectations with regard to easy and favorable testing. Limits and opportunities of different test methods and material card implementations are shown and compared to each other especially focused on typical polymer behavior. Finally the influence of fiber reinforcement is discussed and solutions to determine material parameters by using micro mechanic models (4a MicroMec) are shown.

• 4a impetus - efficient evaluation of material cards for non-reinforced and reinforced thermoplastics

  Peter Reithofer, Martin Fritz, Reinhard Hafellner - 4a engineering GmbH

  LS-DYNA© has included plenty of material cards, each of them offering different scalability and complexity to describe the behavior of non- reinforced thermoplastics. The consideration of the strain rate behavior is included in many material cards, e.g. in the well known MAT_PICEWISE_LINEAR_PLASTICITY. More complex material models can also handle varying compression and tension behavior as well as unloading by using damage functions. One of the recent development results is MAT-SAMP-1 by Du Bois, Kolling, Feucht and Haufe. This specially developed material model for polymers includes a yield surface out of different loading cases and a damage function for better description of unloading. For better use of the above mentioned models a huge amount of tests have to be carried out, to determine the material parameters and to represent the thermoplastic characteristics in crashworthiness simulations. 4a impetus builds up an efficient and reliable process, starting with realistic tests and finally ending up with a validated material card. Recent developments of new test methods for 4a Impetus are presented, that satisfy the needs of complex material models as well as the expectations with regard to easy and favorable testing. Limits and opportunities of different test methods and material card implementations are shown and compared to each other especially focused on typical polymer behavior. Finally the influence of fiber reinforcement is discussed and solutions to determine material parameters by using micro mechanic models (4a MicroMec) are shown.

• 10th International LS-DYNA® Users Conference 2008
• 18 Wheel Truck Dynamic and Durability Analysis using Virtual Proving Ground

  Ramesh Edara, Shan Shih - ArvinMeritor Inc., Nasser Tamini, Tim Palmer, Arthur Tang - Engineering Technology Associates

  Virtual proving ground (VPG) simulations have been popular with passenger vehicles. VPG uses LS-DYNA® based non-linear contact Finite Element analysis (FEA) to estimate fully analytical road loads and to predict structural components durability with PG road surfaces and tire represented as Finite elements. Heavy vehicle industry has not used these tools extensively in the past due to the complexity of heavy vehicle systems and especially due to the higher number of tires in the vehicle compared to the passenger car. The higher number tires in the heavy vehicle requires more computational analysis duration compared to the passenger car. However due to the recent advancements in computer hardware, virtual proving ground simulations can be used for heavy vehicles. In this study we have used virtual proving ground based simulation studies to predict the durability performance of a trailer suspension frame, tractor suspension frame and combination of both frames with 18 wheel on a given PG event. The virtual proving ground was also used to predict the stress, strain time histories, spindle loads and the component fatigue life for the given PG event.

• “Forming to Crash” Simulation in Full Vehicle Models

  Janka Cafolla, Roger W. Hall, David P. Norman, Iain J. McGregor - Corus Automotive

  Improving the accuracy of virtual prototypes helps to shorten product development times and reduces the number of physical prototypes required. One way in which the accuracy of crash analysis can be improved is to include the effects of forming in the material properties. Corus has developed a three-step “Forming to Crash” process to account for formed properties in crash analysis during both concept and detailed vehicle design stages. The first step uses a selection procedure to identify the parts most sensitive to the inclusion of formed properties. The second step uses an approximate “Forming to Crash” method to rapidly estimate the formed properties and reduce the time taken to conduct the analysis during concept design. The third step links a detailed forming analysis to a crash analysis to provide a full “Forming to Crash” technique for use during detailed design development. This three-step process is used by Corus to support customers in the application of advanced high strength steels. Introduction The process of forming a component changes the properties of the material being used. This is generally ignored in the design and validation process of automotive structures even though the changes in material strength and thickness may be substantial. Finite Element tools are now able to predict the as-formed material properties and use these in subsequent crash analysis. However, although the forming effects on the performance of individual components have been reported in the literature [1][2][3][4][5][6][7][8], there are few papers reporting the consequence of including formed properties in full vehicle models [9][10]. This paper presents Corus developed procedures, which are used to include the results of forming simulations in the full vehicle crash model. Corus “Forming to Crash” Three-Step Process A vehicle body structure consists of hundreds of formed components. A detailed analysis of the stamping process can take between 5 to 10 days per part to complete. In order to minimise the time taken for vehicle analysis, it is therefore important to understand which components in the vehicle body structure are sensitive to forming and how the formed properties affect the vehicle crash performance. The identification of the key parts in which to include formed properties is the first stage of a “Forming to Crash” (F2C) three-step process, which has been developed by Corus.

• A 3D Discontinuous Galerkin Finite Element Method with the Bond-Based Peridynamics Model for Dynamic Brittle Failure Analysis

  W. Hu, B. Ren, C.T. Wu, Y. Guo, J. Wu (LSTC)

  Peridynamics is a new nonlocal theory that provides the ability to represent displacement discontinuities in a continuum body without explicitly modelling the crack surface. In this paper, an explicit dynamics implementation of the bond-based peridynamics formulation is presented to simulate the dynamic fracture process in 3D elastic solid. Based on the variational theory, the Discontinuous Galerkin (DG) approach is utilized to formulate the classic peridynamics governing equation. As a result, the spatial integration can be carried out through finite element approach to enforce the boundary conditions, constraints, contacts as well as to handle the non-uniform mesh in the engineering practices. The classic material parameters, such as the elastic modulus and fracture energy release rate are employed for the determination of material response and failure in brittle material. Several numerical benchmarks are conducted to invest the convergence and mesh sensitivity of simulations of dynamic crack propagation process with different refinements. The results demonstrate that the proposed peridynamics formulation can capture the 3D dynamic crack process in brittle material effectively and accurately including multi-crack nucleation, propagation and branching.

• A 6 Year-Old Pediatric Finite Element Model for Simulating Pedestrian Impacts

  Yunzhu Meng, Costin D. Untaroiu (Virginia Tech, virginia Tech-Wake Forest Center for Injury Biomechanics), Berkan Guleyupoglu, Bharath Koya, Scott Gayzik (Wake Forest University School of Medicine, Virginia Tech-Wake Forest Center for Injury Biomechanics)

  In addition to adult pedestrian protection, child pedestrian protection continues to be an important issue in vehicle crash safety. However, with exception of a child headform impact test, all other subsystem tests are designed for prediction of adult pedestrian injuries. The development of a computational child model could be a better alternative that characterizes the whole-body response of vehicle–pedestrian interactions and assesses the pedestrian injuries. Several pediatric pedestrian models have been developed but these existing models have several inherent limitations due to lack of biomaterial data. In this study, an advanced and computationally efficient finite element (FE) model corresponding to a six-year-old (6YO) pedestrian child was developed in LS-DYNA. The model was developed by morphing an existing GHBMC 5th percentile female pedestrian model to a 6-year old child geometry reported in literature. Material properties were applied based upon previously published studies. The standing posture has been used as specified in the EuroNCAP testing protocol. Component validations with simple impactor tests and a full-body validation in a car-to-pedestrian collision (CPC) were performed in LS-DYNA. Overall, the results of the model showed a reasonable correlation to the test data in component validations. The child pedestrian model showed also numerical stability under a typical CPC configuration. In addition, the most common injuries observed in pedestrian accidents including fractures of lower limb bones and ruptures of knee ligaments were predicted by the model. The child model will be further validated and then used by safety researchers in the design of front ends of new vehicles in order to increase pedestrian protection of children.

• A Benchmark Study of CAE Sensor Modeling Using LS-DYNA

  C. C. Chou, P. Chen, J. Le - Passive Safety R&A, Ford Motor Company, Nasser Tamini - ETA

  This paper presents results from a benchmark study of CAE sensor modeling using LS-DYNA. Using the VPG translator, a sensor model was converted from a calibrated RADIOSS model into LS-DYNA input formats for frontal impact simulations carried out in this study. Since two codes have different material laws, element library and functionalities, those deemed to be as closed to RADIOSS were chosen in the translation process. For those that could not be translated directly into LS-DYNA, best engineering judgment was made in selection of appropriate LS- DYNA parameters. Three different frontal impact modes, namely, rigid barrier, pole, and Thatcham offset are simulated in this study. In frontal rigid barrier mode, both 90o barrier and 30o angular impacts are considered. Signals at nine (9) locations were monitored including two sensor signals obtained at the front crash sensor (FCS) and Restraint Control Module (RCM) locations. The quality of CAE data was evaluated using an assessment tool to give objective ratings for comparing results between LS-DYNA and RADIOSS. Sensor signals generated from LS-DYNA were compared with both the RADIOSS and test results. However, only the comparisons with RADIOSS results are presented. By comparing the ratings, LS-DYNA results were, generally speaking, comparable with RADIOSS’ counterparts. Observation of some high frequency response at the onset of acceleration time history obtained at the front crash sensor location at the early stage of this study was improved by LSTC. The study also pointed out areas, i.e. angular and Thatcham impacts, where the LS-DYNA model requires further improvement in the future

• A Brief Look at *MAT_NONLOCAL: A Possible Cure for Erosion Illness?

  Leonard Schwer - Schwer Engineering & Consulting Services

  The computational mechanics literature dealing with damage and failure is filled with work addressing what is termed mesh regularization techniques. These various techniques seek to eliminate, or minimize, the numerical artifact of strain localization. LS-DYNA® provides a technique for attempting to regularize meshes with damage and failure via the keyword *MAT_NONLOCAL. The non-local implementation in LS-DYNA is based on the work of Pijaudier-Cabot and Bazant (1987). The non-local treatment basically attempts to average damage/failure values of neighboring elements to minimize the mesh dependency of the results.

• A Brittle Damage Model: Implementation into LS-DYNA and Application to Normal Plate-on-Plate Impact

  Martin N. Raftenberg - U.S. Army Research Laboratory

  A brittle damage model developed by M. A. Grinfeld was implemented in the LS-DYNA finite element code and applied to the simulation of normal plate-on-plate impact. The model introduces a state variable measure of damage that evolves in proportion to the elastic strain energy. The model degrades the elastic shear modulus in proportion to the state variable’s current level. The implementation procedure by means of the LS-DYNA user- material interface is described. In a simulation of normal plate-on-plate impact, the model produced a gradient in elastic properties within the initially homogeneous target, and this gradient led to a partial reflection of the unloading wave. For a range of values for the material constants introduced by the damage model, the target’s free-surface velocity showed a gradual increase over time following the arrival of the initial compressive shock. This observation is discussed in light of the phenomenon of failure waves.

• A Cohesive Element Model for Large-Scale Crash Analyses in LS-DYNA ®

  Johan Kolstø Sønstabø, David Morin, Magnus Langseth (SIMLab and CASA)

  In a recent study the cohesive element model *MAT_240 was evaluated for macroscopic modelling of two different Flow-Drill Screw (FDS) connections in large-scale analyses [1]. The study showed that *MAT_240 does not have sufficient flexibility to describe the macroscopic behaviour of the connections. In particular, the force level and initial stiffness in mixed-mode loadings were severely over-estimated. The lack of flexibility to control the mixed-mode behaviour was also pointed out by Sommer and Maier [2], who investigated self-piercing rivet connections. This paper presents a new cohesive element model for use in LS-DYNA. The model is based on *MAT_240, presented by Marzi, et al. [3], with added flexibility to control the behaviour under mixed-mode loadings.

• A Cohesive Model for Ice and its Verification with Tensile Splitting Tests

  H. Herrnring, L. Kellner, J. M. Kubiczek, S. Ehlers (TUHH)

  Ships and offshore structures operating in areas such as the Arctic have to be designed to withstand ice induced loads, e.g. from ice floe impact. This is mostly done with empirical methods, which have several drawbacks, e.g. they only give upper estimates of global loads. Numerical simulations of ice interaction are a desirable remedy, but their accuracy is currently limited if the material model doesn’t account for fracture processes. One approach is to use an elastic bulk material model along with the cohesive zone method (CZM) to model all inelastic deformation, i.e. fracture. Here, this approach is applied to simulate tensile splitting tests. The focus is on parameter identification and numerical instabilities for fine discretizations.

• A COMPARATIVE REVIEW OF DAMAGE AND FAILURE MODELS AND A TABULATED GENERALIZATION

  P.A. Du Bois - Consulting Engineer, Germany, S. Kolling, M. Feucht - DaimlerChrysler AG, Germany, A. Haufe - Dynamore GmbH, Germany

  Reliable prediction of damage and failure in structural parts is a major challenge posed in engineering mechanics. Although solid material models predicting the deformation behaviour of a structure are increasingly available, reliable prediction of failure remains still open. With SAMP (a Semi-Analytical Model for Polymers), a general and flexible plasticity model is available in LS-DYNA since version 971. Although originally developed for plastics, the plasticity formulation in SAMP is generally applicable to materials that exhibit permanent deformation, such as thermoplastics, crushable foam, soil and metals. In this paper, we present a generalized damage and failure procedure that has been implemented in SAMP and will be available in LS-DYNA soon. In particular, important effects such as triaxiality, strain rate dependency, regularization and non-proportional loading are considered in SAMP. All required physical material parameters are provided in a user-friendly tabulated way. It is shown that our formalism includes many different damage and failure models as special cases, such as the well-known formulations by Johnson-Cook, Chaboche, Lemaitre and Gurson among others.

• A Comparative Study of Modeling Approaches for External Structures in Mine Blast Simulations of an Armored Military Vehicle

  İsmet Kutlay ODACI, Samet Emre YILMAZ, İlker KURTOĞLU

  External structures are known to be critical in ensuring the protection of occupants in military vehicles during mine blast events. There are variety of modelling approaches that can be employed to represent external structures in mine blast simulations of armored military vehicles. This study aims to present an accurate configuration considering the modelling efforts and tight project schedules by comparing different modeling techniques applied to external structures, such as add-on armor plates and other external subsystem components. A whole vehicle finite element model is utilized for an on-going research and development project to evaluate the effectiveness of these modeling approaches by comparing simulation results with live fire test data of Hybrid III dummy and plastic deformations of the hull structure. The findings emphasize that the modelling approach of not only primary protective structures but also other external components significantly contributes to better representation of the tests. Configurations featuring accurately modeled external structures demonstrate improved accuracy in occupant safety assessment. The outcomes of the study contribute to enhancing the efficiency and reliability of the conceptual design phase by providing faster and relatively reliable finite element solutions, specifically in terms of representing external structures in the simulations.

• A Comparative Study of the Hexahedral Elements in LS-DYNA for Crashworthiness Simulation

  S. E. Hoque, S. Scheiblhofer, S. Ucsnik (LKR Leichtmetallkompetenzzentrum Ranshofen)

  The mesh behaviour and convergence rate of six hexahedral element formulations in LS-DYNA were investigated by means of crashworthiness simulation. The element formulations are: constant stress solid element (ELFORM 1), fully integrated S/R (Selective Reduced) solid element (ELFORM 2), fully integrated S/R solid element with reduced transverse shear locking (ELFORM -1 and ELFORM -2), 20-noded serendipity element (ELFORM 23), and 27-noded fully integrated S/R quadratic solid element (ELFORM 24). FE-simulations of the axial crushing of aluminium profiles were set up with these element formulations. The convergence rate of each element formulation was investigated by varying the mesh resolution. For validating the simulation results, four extruded profiles with rectangular hollow cross-sections were experimentally tested under quasi-static axial crushing load. On that basis, the performance of each element formulation was investigated in terms of their convergence rate, accuracy, and computational cost to elaborate an approach for future tasks. Finally, various aspects which should be considered while using these element formulations for this class of problem are discussed.

• A COMPARISON BETWEEN EXPERIMENTAL TESTING AND NUMERICAL SIMULATIONS OF IMPACT LOADING ON ALUMINUM AND MAGNESIUM STEERING WHEEL ARMATURES

  William J. Altenhof - The University of Windsor, William D. Ames - K.S. Centoco Limited

  In the present automotive industry, all corporations are focusing on developing automobiles which are light weight, fuel efficient, conform to a level of safety outlined by government regulations, and are available to the consumer at a reasonable cost. The automobile industry has placed a significant amount of time and research funding into developing vehicles which can meet these requirements. K.S. Centoco Ltd., a steering wheel manufacturer, located in Windsor, Ontario, Canada, has developed a testing machine to investigate collisions occurring with steering wheels. This machine considers several experimental parameters in impact testing while providing a large amount of information to be obtained in an experiment. Experimental testing was conducted on a four spoke steering wheel armature which is manufactured from a magnesium alloy. In an effort to compare the structural worthiness of magnesium and aluminum alloys in an impact situation, the identical armature was fabricated from a proprietary aluminum alloy and impact experiments were also conducted with the geometrically identical aluminum armature. Numerical simulation of the experimental process has also been conducted using LS-DYNA. Detailed four spoke steering wheel armature finite element models (employing both magnesium and aluminum alloys) have been developed and simulated under similar conditions which were conducted experimentally. Comparisons between experimental tests at six different impact situations with collisions between the steering wheel armature and a rigid plate are presented in this paper. As well, comparison of the finite element model is considered by investigating changes in the element formulation associated with the armature. The experimental and numerical observations indicate that the predictive capabilities of the aluminum material model are better developed than the magnesium material model. In addition, selection of the finite element formulation significantly affects the numerical results.

• A Comparison between Three Different Blast Methods in LS-DYNA: LBE, MM-ALE, Coupling of LBE and MM-ALE

  Z. S. Tabatabaei (PhD Candidate, Missouri University of Science and Technology), J. S. Volz (Assistant Professor, Missouri University of Science and Technology)

  A previous experimental test was modeled in LS-DYNA®. Three different methods of simulation were performed. These methods are empirical blast method, arbitrary Lagrangian Eulerian (ALE) method, and coupling of Lagrangian and ALE method. Free field pressure history recorded from experimental test was compared with the first method. Peak pressure for all these three methods were compared together and discussion of results is provided. Keyword: Blast, Lagrangian (LAG), Load Blast Enhanced (LBE), Multi-Material Arbitrary Lagrangian Eulerian (MM- ALE), LS-DYNA

• A Comparison between Three Air Blast Simulation Techniques in LS-DYNA

  H. Bento Rebelo, C. Cismasiu (Universidade NOVA de Lisboa)

  When simulating structures subjected to the effects of blast loading, one might resort to three different methods of simulation. These methods are the empirical blast method, also known as Load Blast Enhanced (LBE), the Arbitrary Lagrangian Eulerian (ALE) method, and a coupling method that allows the application of empirical blast loads on air domain simulated with the ALE formulation. Furthermore, for the ALE method, both a mapping technique, that allows the mapping of data from 2D ALE simulations to 2D and 3D ALE meshes, and a complete 3D ALE simulation could be performed. In order to verify and compare the efficiency and accuracy of these air blast methods, an air blast loading on a reinforced concrete slab is modelled. Additionally, mesh convergence studies of 2D and 3D ALE simulations are performed.

• A Comparison between two Methods of Head Impact Reconstruction

  Arghavan Talebanpour, Lloyd Smith, School of mechanical and material engineering Washington State University

  Reconstructing head impacts using computational models is an important tool in understanding brain injury mechanisms. Head impacts are often reconstructed by impacting an Anthropomorphic Test Device (ATD) with an object of interest. The head accelerations are measured and applied to a biofidelic finite element model. Little work has been done, however, to determine how the ATD accelerations applied to a numeric model approximate the brain response an actual impact. The following considered head impacts from a solid sports ball. The brain response of a biofidelic model was compared in two scenarios: accelerations were applied to the model from an impacted by a ball; the head-ball impact was simulated directly in LS-DYNA® with the same speed, direction, and location as occurred with the ATD.

• A Comparison of Damage and Failure Models for the Failure Prediction of Dual-Phase Steels

  F. Andrade (DYNAmore); M. Feucht (Daimler)

  The aim of this contribution is the comparison of different damage failure models that are available in LS-DYNA. In particular, the focus is concentrated on the failure prediction of dual-phase steels which are largely used in the automotive industry. Typically, such alloys provide a good compromise between ductility and strength for which this kind of material is also often used in safety relevant components. Examples are parts of B-pillars, side rails and cross members, i.e., parts that may be subjected to intensive loadings in a high speed car crash scenario. In contrast to some other usual alloys, dual-phase steels are often reasonably isotropic and well described by J2-based plasticity. This allows the use of simple and very efficient material formulations (e.g., *MAT_024 in LS-DYNA [1]) without excessively losing accuracy in crash simulations. Despite the fact that the elastoplastic behavior of such alloys can be generally well captured by simple plasticity models, the fracture behavior in practical applications still demands the consideration of several effects like stress state dependence, nonlinear paths, material instability, spurious mesh dependence, among others. Therefore, we consider three different damage/failure models available in LS-DYNA in order to calibrate the fracture behavior of a typical dual-phase steel: (a) the GISSMO damage/failure model [1–3]; (b) the Gurson-Tvergaard-Nedlemann model [4, 5] and the Cockcroft-Latham failure model as implemented in *MAT_135 in LS-DYNA [1, 6]. We will shed some light on the differences among these models and verify their ability in reproducing experimental data on the coupon level for different stress states. The goal is to understand the advantages and limitations of each model concerning the prediction of failure. A detailed discussion will then follow the results obtained with the three models.

• A Comparison of Isotropic (*MAT_224) and Anisotropic (*MAT_264) Material Models in High Velocity Ballistic Impact Simulations

  Sean Haight, Cing-Dao “Steve” Kan (Center for Collision Safety and Analysis (CCSA)), Paul Du Bois (Consulting Engineer)

  To improve the modeling of metals in high velocity impacts, there have been many developments in constitutive material modeling for LS-DYNA ® . One such advancement is the development of the Tabulated Johnson-Cook material model (*MAT_224). *MAT_224 is a tabulated material model with strain rate and temperature dependency. Additionally, this model includes a failure criteria as a function of triaxiality, Lode parameter, temperature, strain rate and element size. This model has been used successfully in the simulation of numerous materials in high velocity ballistic impact load cases. One drawback to the original Tabulated Johnson-Cook material model is that it is implemented with von Mises isotropic plasticity. Therefore, this material model is not ideal for simulating metals that are anisotropic or asymmetric. Subsequently, an anisotropic and asymmetric version of the Tabulated Johnson-Cook model was developed to simulate these materials. The *MAT_264 material model maintains all the capabilities of the *MAT_224 model, but it adds the ability to define the material response in the 0-degree, 45-degree, 90-degree and thickness directions. Additionally, it allows for directional tension-compression asymmetry in the material. Strain rate dependency, temperature dependency, and the failure model are retained from the Tabulated Johnson-Cook model. By using a previously developed failure model and limited material specimen testing, an industrial material characterization was developed for a 6.35 mm thick Ti-6Al-4V rolled plate. Specimen testing of this titanium alloy plate reveals that this material exhibits some anisotropy and asymmetry. NASA cylindrical ballistic tests were simulated with both the *MAT_224 and *MAT_264 material models. First, the isotropic implementation of the *MAT_264 material model is compared to the *MAT_224 model. Second, the anisotropic implementation of the *MAT_264 model is compared to the isotropic *MAT_224 model. Multiple impact velocities are simulated and the resulting exit velocities, internal energies and eroded internal energies are used to compare each material model.

• A Comparison of Monolithic and Layered-Plate Configurations for Containment

  Thomas J. Vasko, PhD, PE (Central Connecticut State University, New Britain)

  Jet-engine fan, compressor, and turbine blades require containment cases to ensure that any released blade fragments are contained within the engine and do not penetrate the case, where they can damage critical engine components or penetrate the passenger cabin. To determine the centrifugal strength of turbomachinery rotors, disk-burst tests are performed in vertical-axis spin pits that require containment cases to ensure the safety of the surrounding test area. In these applications, the containment cases are sized to determine the minimum thickness the case must have in order to contain all rotating-part fragments. The current study compares a monolithic plate with various layered-plate configurations to assess containment capability as determined by the perforation velocity, the lowest projectile velocity that completely penetrates the target. The targets include a monolithic plate and several layered-plate configurations with and without gaps. The projectile is a rigid sphere that impacts the target normal to the surface. The target plates are made of titanium-6Al-4V that is modeled using the MAT_TABULATED_JOHNSON_COOK (MAT_224) constitutive model in LS-DYNA ® . This is an elastic viscoplastic material model with strain rate and temperature-dependent stress versus strain curves. In addition, plastic failure strain is defined as a function of triaxiality and Lode parameter, strain rate, temperature, and element size. Results of the study can be used to determine the optimum containment-case configuration for a variety of high-speed rotating components.

• A Comparison of recent Damage and Failure Models for Steel Materials in Crashworthiness Application in LS-DYNA

  Dr. André Haufe (Dynamore GmbH), Frieder Neukamm, Dr. Markus Feucht (Daimler AG), Paul DuBois (Consultant), Dr. Thomas Borvall (ERAB)

  With increasing requirements on crashworthiness, and light-weight car body structures being a central issue in the future of automotive development, the use of high strength steel grades has become wide-spread in modern vehicles. Since these materials all too often show significantly lower ductility than conventional steels, it is of great importance to precisely predict their failure in crash loading conditions. Hence constitutive models in crashworthiness applications need to be able to correctly predict damage and failure mechanisms. These aforementioned, enhanced models are regularly based on a larger number of variables that define the loading history based on stress or strain measures and on accumulated plastic strain and damage variables more or less accurate. Moreover, these models may require initialization with locally computed history properties prior to a crashworthiness simulation in order to predict the subsequent loading response correctly. Furthermore it should be mentioned that orthotropic properties of steel sheets play a major role in the forming process. Hence one may expect that orthotropic behaviour in damage accumulation may also be a major mechanism when failure prediction along the forming-to-crash process chain is evaluated. It is therefore of great importance to not only evaluate the many available models in LS-DYNA based on their performance achieved in crash loading scenarios but also take the production step with mapping of history data into account. The present paper will focus on the different models available in LS-DYNA, e.g. Gurson, Johnson-Cook, GISSMO etc. and discuss the advantages and disadvantages in application, calibration and predictive performance in the light of the producibility-to-servicability simulation chain.

• A Complementary Experimental and Modeling Approach for the Characterization of Maple and Ash Wood Material Properties for Bat/Ball Impact Modeling in LS-DYNA

  Joshua Fortin-Smith, James Sherwood, Patrick Drane (University of Massachussets), David Kretschmann (U.S. Forest Products Laboratory)

  To assist in developing LS-DYNA finite element models of wood baseball bats that can be used to explore the relationship between bat profile and bat durability, an experimental program was conducted to characterize the mechanical behavior of maple and ash woods for the range of densities used to make major-league quality baseball bats. The test program included four-point bend testing to determine the elastic moduli and breaking strength and Charpy impact testing to determine strain to failure as a function of strain rate. The MAT_WOOD material was used to describe the mechanical behavior of the wood, and the input parameters were calibrated by comparing the results of LS-DYNA finite element simulations of the Charpy tests to the experimental test data. This paper describes the experimental characterization program, summarizes the material parameters and presents a comparison of the finite element simulations of the Charpy testing and bat/ball impacts to experimental results.

• A Comprehensive Study on the Performance of Implicit LS-DYNA

  Y.-Y. Lin (Hewlett-Packard Company)

  This work addresses four aspects of Implicit LS-DYNA’s performance. First, Implicit LS-DYNA’s scalability is characterized on multicore platforms. Second, the effectiveness of the GPU implementation is examined. Third, the effect of memory configuration on performance and information on how to configure optimal memory size for a system are presented. And fourth, the performance of out-of-core solutions is discussed.

• A Computational and Experimental Analysis of Ballistic Impact to Sheet Metal Aircraft Structures

  Matti J. Loikkanen - Boeing Commercial Airplanes, Murat Buyuk, Cing-Dao (Steve) Kan - The George Washington University, Nick Meng - SGI

  The ballistic resistance of 2024-T3 and 2024-T351 alloy aluminum flat plates to aircraft engine fragments is evaluated experimentally. Gas and powder gun tests are performed to determine the ballistic speed limit of a spherical steel bullet representing the engine fragment with a diameter of 0.5 inch. The rectangular flat aluminum specimens are prepared as 12 x 12 inch and with three different thickness combinations of 1/16”, 1/8” and 1⁄4”. A normal impact scenario is considered in terms of the orientation of the specimens to the impacting projectile. A computational model is constructed using Johnson-Cook (J-C) material model considering the thermo-viscoplastic behavior of the material with an accumulated damage and an equation of state model. The experimental model was implemented in LS-DYNA to simulate impact tests and validate the ballistic limit findings with a comparison for the failure mechanisms. Under these controlled geometries, controlled impact conditions, and characterized materials with well- defined material properties, experimental damage characteristics are used to determine the essential failure parameters in the material model.

• A constitutive equation for the aging of elastomer and application to dummy impact programs

  William W. Feng, John O. Hallquist, Christoph Maurath - Livermore Software Technology Corp

  A constitutive equation for chronorheologically simple materials that describes the aging and viscoelastic behaviors of elastomer is presented. A simulated numerical uniaxial relaxation test of a material at various aging stages has been performed. The simulated experimental results demonstrate the chronorheological effect and are used further to determine the material property functions in the constitutive equation. A test of an elastomer at various aging stages has been performed. It demonstrated the same effect as the simulated numerical example. The applications of this constitutive equation to dummy impact programs are mentioned.

• A Constitutive Formulation for Polymers Subjected to High Strain Rates

  S. Kolling, M. Feucht - DaimlerChrysler AG, A. Haufe - Dynamore GmbH, P.A. Du Bois - Consulting Engineer

  Reliable prediction of the behavior of structures made from polymers is a topic under considerable investigation in engineering practice. Especially, if the structure is subjected to dynamic loading, constitutive models considering the mechanical behavior properly are still not available in commercial finite element codes yet. In our paper, we present a new constitutive law for polymers which recovers important phenomena like necking, crazing, strain rate dependency, unloading behavior and damage. In particular, different yield surfaces in compression and tension and strain rate dependent failure, the latter with damage induced erosion, is taken into account. All relevant parameters are given directly in the input as load curves, i.e. time consuming parameter identification is not necessary. More- over, the models by von Mises and Drucker-Prager are included in the description as special cases. With the present formulation, standard verification test can be simulated successfully: tensile and compression test, shear test and three point bending tests.

• A constitutive model for thermoplastics with some applications

  Arild Holm Clausen, Mario Polanco-Loria1, Torodd Berstad and Odd Sture Hopperstad - Norwegian University of Science and Technology

  A constitutive model for thermoplastics is outlined in this paper. The model consists of two parts: A hyperelastic-viscoplastic response due to intermolecular resistance denoted Part A, and an entropic hyperelastic response due to re-orientation of molecular chains called Part B. Both parts are developed within a framework for finite strains. The main constituents are the Neo-Hookean model describing large elastic deformations, the pressure-sensitive Raghava yield function, a non-associated visco-plastic flow potential and Anand’s stress- stretch relation representing the intramolecular stiffness. The 11 non-zero coefficients of the model are identified from uniaxial tension and compression tests on two materials, HDPE and PVC, which are respectively semi-crystalline and amorphous thermoplastics. Subsequently, it is employed in numerical simulations of three-point bending tests on the same materials. The model gives satisfactory predictions when compared to experimental behaviour.

• A constitutive model for thermoplastics intended for structural applications

  Mario Polanco-Loria, Torodd Berstad - SINTEF Materials and Chemistry / Structural Impact Laboratory (SIMLab), Arild Holm Clausen, Odd Sture Hopperstad - Department of Structural Engineering, NTNU/Structural Impact Laboratory (SIMLab)

  This paper presents a hyperelastic-viscoplastic constitutive model for thermoplastics [1]. It is partly based on a model proposed by Boyce et al. [2]. The model involves a hyperelastic- viscoplastic response due to intermolecular resistance, and an entropic hyperelastic response due to re-orientation of molecular chains. A Neo-Hookean material model is selected for describing large elastic deformations. Moreover, the Raghava plastic yield surface [3] is introduced to capture the pressure sensitivity behaviour, and a non-associative visco-plastic flow potential is assumed for volumetric plastic strain control. The strain-rate effects are formulated in a format well-suited for structural applications. Finally, the intramolecular stiffness is represented with Anand’s stress-stretch relation [4]. The model is developed within a framework developed for finite elastic and plastic strains, using a multiplicative decomposition of the deformation gradient. It is implemented as a user-defined model in LS-DYNA [5]. The material model requires 10 parameters which are easy to identify from true stress-strain curves obtained from uniaxial tension and compression tests. In this paper, the parameters are determined from experimental tests on a polyethylene material with high density (PEHD). Subsequently, the model is employed in numerical simulations of the uniaxial tension test and a quasi-static test on a centrally loaded plate. The numerical model gives satisfactory predictions when compared to the observed experimental behaviour.

• A constitutive model for thermoplastics intended for structural applications

  Mario Polanco-Loria, Torodd Berstad - SINTEF Materials and Chemistry / Structural Impact Laboratory (SIMLab), Arild Holm Clausen, Odd Sture Hopperstad - Department of Structural Engineering, NTNU/Structural Impact Laboratory (SIMLab)

  This paper presents a hyperelastic-viscoplastic constitutive model for thermoplastics [1]. It is partly based on a model proposed by Boyce et al. [2]. The model involves a hyperelastic- viscoplastic response due to intermolecular resistance, and an entropic hyperelastic response due to re-orientation of molecular chains. A Neo-Hookean material model is selected for describing large elastic deformations. Moreover, the Raghava plastic yield surface [3] is introduced to capture the pressure sensitivity behaviour, and a non-associative visco-plastic flow potential is assumed for volumetric plastic strain control. The strain-rate effects are formulated in a format well-suited for structural applications. Finally, the intramolecular stiffness is represented with Anand’s stress-stretch relation [4]. The model is developed within a framework developed for finite elastic and plastic strains, using a multiplicative decomposition of the deformation gradient. It is implemented as a user-defined model in LS-DYNA [5]. The material model requires 10 parameters which are easy to identify from true stress-strain curves obtained from uniaxial tension and compression tests. In this paper, the parameters are determined from experimental tests on a polyethylene material with high density (PEHD). Subsequently, the model is employed in numerical simulations of the uniaxial tension test and a quasi-static test on a centrally loaded plate. The numerical model gives satisfactory predictions when compared to the observed experimental behaviour.

• A Continuum Model of Deformation and Damage for API X70 Steel Based on the Theory of Strain Gradient

  Mohammed Anazi, Hussein Zbib, Washington State University, School of Mechanical and Materials Engineering

  This work shows the results of a continuum model of deformation and damage for API X70 steel based on the strain gradient theory. The model is developed according to the continuum mechanics of the elastic/viscoplastic framework. The constitutive equations of the model include the dislocation theory according to the roles of the statistically stored and geometrically necessary stored dislocation densities during plastic deformation. In addition, effects of nucleation and growth of voids are considered within the constitutive equations as a ductile failure based on a classical isotropic damage model. Then, the model is examined for scale and strain rate effects. The developed model is implemented into LS-DYNA® by writing a subroutine within USER_DEFINED_MATERIAL_MODELS (UMAT). A ASTM tensile test is simulated to examine the validity of the model. The results show a good agreement with experimental data found in the literature.

• A Contribution to New ALE 2D Method Validation

  Nicolas VAN DORSSELAER, Vincent LAPOUJADE - Alliance Services Plus,

  Since LS-DYNA® v971 r4, a new ALE 2D method is available. Several finite element studies were performed by AS+ to evaluate the precision of this method in pure Multi-Materials Euler studies . Pure Multi-Materials Euler was tested on Impacts and Explosives studies from Defense and Spatial fields. A High Velocity Impact, a Long Rod Penetration, an Explosively Formed Projectile, a Shaped Charge Jet and an Air Blast were modeled using 2D axisymmetric models. Results were compared to experimental data extracted from reference papers. The very good precision obtained with the 2D ALE method and its ability to represent very dynamic phenomenon will be shown.

• A contribution to validation of SPH new features

  Thomas Beal, Nicolas Van Dorsselaer, Vincent Lapoujade (DynaS+)

  Since 1998, the Smoothed Particle Hydrodynamics (SPH) method has been developed by LSTC in LS-DYNA®. This method is called a meshfree method because traditional finite elements are replaced by particles which are not physically connected but mathematically linked. It is an alternative to the classical Lagrangian Finite Elements method and is used to simulate problems where materials are submitted to hydrodynamic deformation modes, such as high velocity impacts. In order to improve the capabilities of SPH in LS-DYNA, LSTC recently developed several new functionalities available in the latest versions of LS-DYNA. The first new feature is the possibility to choose a Lagrangian kernel for SPH particles, which means there are always the same neighbors for one SPH node (more stability in tension). The second option is Hybrid SPH / Solid elements, designed to couple the benefits of both SPH and Lagrangian finite elements. With these new Hybrid elements, it is now possible to switch from SPH to solid elements using certain criteria and to realize a better transition between SPH and finite elements areas (no more tied contacts needed). This paper presents the DynaS+ contribution to the test and the validation of these new SPH options. Simple test cases and more complicated cases representative of industrial problems have been performed to assess the behavior and the interest of these new features. All tests have been conducted using LS-DYNA V970 R6.0.0 released in 2012. A comparison with older modeling ways will show the benefits they already bring, and the ones they will bring in the future, when their development will be completed.

• A Correlation Study between MPP LS-DYNA Performance and Various Interconnection Networks — a Quantitative Approach for Determining the Communication and Computation Costs

  Yih-Yih Lin - Hewlett-Packard Company

  As MPP LS-DYNA uses the message-passing paradigm to obtain parallelism, the elapsed time of an MPP LS-DYNA simulation comprises of two parts: computation cost and communication cost. A quantitative approach for determining the communication cost and, hence, the computation cost and the speedup of an MPP LS-DYNA simulation is presented. Elapsed times, characteristic—latency and bandwidth—of interconnect networks, and message patterns are first measured, and then the method of least square errors is applied to estimate the two costs. This approach allows one to predict the performance, or the speedup, of MPP LS-DYNA simulations with any interconnect network whose characteristics is known. Also, while conducting this performance study of MPP LS-DYNA, loss of accuracy in single-precision (32-bit) MPP LS-DYNA simulations has been found. This finding and the advantage of double-precision (64-bit) arithmetic are presented. INTRODUCTION - Theory for Performance of MPP LS-DYNA To run an N-processor MPP LS-DYNA simulation, or job, an interconnect network, or called simply as interconnect, must first be established to connect the N processors; the collection of the N processors and the interconnect is called an N-processor cluster. In this paper, we will consider only the case that the N processors are of the same kind. For such a job, MPP LS-DYNA starts by decomposing the geometrical configuration of the model into N sub-domains. Each of the N processors is assigned to perform computation on one of the sub-domains; meanwhile, messages are passed among all those processors so that necessary physical conditions, such as 1 2 N force conditions, can be enforced. Let T comput, T comput, …, T comput be each 1 2 N processor’s computation cost, and let T comm, T comm, …, T comm be each processor’s 1 2 communication cost. Define the computation cost Tcomput as max (T comput, T comput, N 1 2 N …, T comput) and the communication cost Tcomm as max(T comm, T comm, …, T comm), respectively. Then the job’s elapsed time can be described as: T elapsed = Tcomput + Tcomm (1) For a given decomposition, the computation cost Tcomput is fixed. In contrast, the communication cost Tcomm varies with the characteristics of interconnects used. The term “speedup” is defined as the ratio T elapsed, 1-processor / T elapsed, N-processor. In general, speedups are smaller than N. Since for the 1-processor job the communication cost Tcomm is zero, the perfect speedup of N folds can be realized only under the unrealistic conditions of zero communication cost, i.e., Tcomm = 0, and perfectly 1 2 N balanced decomposition, which renders T comput = T comput = …= T comput. Assuming that the N processors are of the same kind, the variation of T comput, 2 N T comput, …, T comput arises out of the unbalanced decomposition of the N subdomains. It is extremely difficult to find a universal algorithm to decompose a model with a balanced decomposition. MPP LS-DYNA does provide features, as documented in pfile in parallel specific options, for users to provide hints to get a more balanced decomposition than the default.

• A Coupled Thermal and Mechanical Model of Sliding Wear

  S. S. Akarca, W. J. Altenhof, A. T. Alpas - University of Windsor, Canada

  Sliding wear of aluminum alloys induce plastic deformation below the contact surfaces even at light loads. Experimental evidence exists for damage accumulation in the form of nucleation of voids and microcracks around the second phase particles in the material layers adjacent to the contact surface. Crack propagation at a certain depth below the surface may lead to the creation of long and thin wear debris particles. The objective of this work was to study deformation and damage accumulation processes in aluminum alloys during sliding wear. LS-DYNA was used to model multiple sliding contacts between an aluminum alloy and a steel counterface. The material model used in the finite element analysis was based on the stress/strain behaviour of a 356 Al (Al-7%Si) alloy determined directly from the analysis of the deformation state of the subsurfaces generated during sliding wear tests. Strain rate and thermal effects were also considered through a coupled thermal and mechanical analysis using material type 106 in LS-DYNA (*MAT_ELASTIC_ VISCOPLASTIC_THERMAL). The accumulation of stresses and strains were studied as a function of contact cycle number. The Lagrangian thermal and mechanical coupled finite element model developed in LS-DYNA was successful to simulate deformation of the aluminum alloy during sliding contacts. Subsurface distributions of the hydrostatic pressure, strain rate and temperature, which are difficult to characterize experimentally or theoretically for work hardening materials, were determined for different loading conditions during sliding contacts. Predicted distributions of stresses and strains were used to model subsurface damage gradient and delamination of subsurface layers. Numerical investigation of a void growth model based on a ductile void growth theory showed the presence of a damage gradient and a critical depth at which delamination cracks might initiate and propagate.

• A Coupling of Empirical Explosive Blast Loads to ALE Air Domains in LS-DYNA

  Todd P. Slavik - Livermore Software Technology Corporation

  A coupling method recently implemented in LS-DYNA® allows empirical explosive blast loads to be applied to air domains treated with the multi-material arbitrary Lagrangian-Eulerian (ALE) formulation. Previously, when simulating structures subjected to blast loads, two methods of analysis were available: a purely Lagrangian approach or one involving the ALE and Lagrangian formulations coupled with a fluid-structure interaction (FSI) algorithm. In the former, air blast pressure is computed with empirical equations and directly applied to Lagrangian elements of the structure. In the latter approach, the explosive as well as the air are explicitly modeled and the blast wave propagating through the ALE air domain impinges on the Lagrangian structure through FSI. Since the purely Lagrangian approach avoids modeling the air between the explosive and structure, a significant computational cost savings can be realized – especially so when large stand-off distances are considered. The shortcoming of the empirical blast equations is their inability to account for focusing or shadowing of the blast waves due to their interaction with structures which may intervene between the explosive and primary structure of interest. The new method presented here obviates modeling the explosive and air leading up the structure. Instead, only the air immediately surrounding the Lagrangian structures need be modeled with ALE, while effects of the far-field blast are applied to the outer face of that ALE air domain with the empirical blast equations; thus, focusing and shadowing effects can be accommodated yet computational costs are kept to a minimum. Comparison of the efficiency and accuracy of this new method with other approaches shows that the ability of LS-DYNA® to model a variety of new blast scenarios has been greatly extended.

• A Coupling of Empirical Explosive Blast Loads to ALE Air Domains in LS-DYNA

  Todd P. Slavik - Livermore Software Technology Corporation

  A coupling method recently implemented in LS-DYNA® allows empirical explosive blast loads to be applied to air domains treated with the multi-material arbitrary Lagrangian-Eulerian (ALE) formulation. Previously, when simulating structures subjected to blast loads, two methods of analysis were available: a purely Lagrangian approach or one involving the ALE and Lagrangian formulations coupled with a fluid-structure interaction (FSI) algorithm. In the former, air blast pressure is computed with empirical equations and directly applied to Lagrangian elements of the structure. In the latter approach, the explosive as well as the air are explicitly modeled and the blast wave propagating through the ALE air domain impinges on the Lagrangian structure through FSI. Since the purely Lagrangian approach avoids modeling the air between the explosive and structure, a significant computational cost savings can be realized – especially so when large stand-off distances are considered. The shortcoming of the empirical blast equations is their inability to account for focusing or shadowing of the blast waves due to their interaction with structures which may intervene between the explosive and primary structure of interest. The new method presented here obviates modeling the explosive and air leading up the structure. Instead, only the air immediately surrounding the Lagrangian structures need be modeled with ALE, while effects of the far-field blast are applied to the outer face of that ALE air domain with the empirical blast equations; thus, focusing and shadowing effects can be accommodated yet computational costs are kept to a minimum. Comparison of the efficiency and accuracy of this new method with other approaches shows that the ability of LS-DYNA® to model a variety of new blast scenarios has been greatly extended.

• A critique of the THUMS lower limb model for pedestrian impact applications

  T. Cloake, C. Bastien (Coventry University), J. Hardwicke (University Hospitals Coventry and Warwickshire), D. Venetsanos (Coventry University), C. Neal-Sturgess (University of Birmingham)

  The Total Human Model for Safety (THUMS) is widely used for biomechanics research and validated at the component and full-body levels. Nonetheless, some authors have reported differences in predictions between the model and real-life injuries, particularly in the lower limbs. This study aims to perform an extensive critique of the THUMS lower limb and identify areas for improvement. The THUMS model was assessed across quasi-static and dynamic validation tests to understand geometry, material properties and response to impact. The study has highlighted that the THUMS’ geometry is comparable to published cadaveric data for bones and ligaments, but soft tissues (muscle, adipose and skin) and fascia have significant simplifications.

• A Customized Job Manager for Metal Forming Simulations with LS-DYNA®

  Yuzhong Xiao, Xinhai Zhu, Li Zhang, Houfu Fan, Livermore Software Technology Corporation

  In the metal forming analysis, the simulation time of each job is relatively short. However, due to the iterative modifications of the forming tools based on the simulation results, generally there would be several numerical tryouts. Also in addition to those with a single keyword file input, the number of simulation jobs consisting of several (e.g. the progressive die forming) or even dozens of sequential simulations (e.g. the iterative springback compensation process), is increasing. In comparison to conventional simulations, simulation submission and file management of these jobs have become more time-consuming. Therefore, a simple application (Job Manager) has been customized for LS-DYNA metal forming users to manage the simulation jobs more efficiently and reduce the total time cost.

• A Cyclic Damaged Plasticity Model: Implementation and Applications

  Yuli Huang, Stephen A. Mahin - University of California at Berkeley

  In analysis and design of structures subjected to earthquakes, the cyclic and dynamic nature of the response leads to complications. Material models need to account for cyclic plasticity, including deterioration and eventual failure due to low-cycle fatigue. A cyclic damage plasticity model MAT_DAMAGE_3 (MAT_153, LSTC 2007) is implemented to combine Armstrong-Frederick/Chaboche nonlinear kinematic hardening, isotropic hardening, and Lemaitre isotropic damage evolution based on continuum damage mechanics. By appropriately choosing parameters, this model can reproduce an approximation to the widely-accepted Manson-Coffin low-cycle fatigue rule without of cycle counting. This makes it possible to model the decrease in the material’s ability to deform inelastically. The material model is applied to assess the behavior of a steel structure subjected to deterioration and failure.

• A data-driven methodology for the automated analysis and explanation of system behavior in crash simulations

  Janis Mathieu, Michael Di Roberto, Michael Vielhaber

  Attributable to model size and complexity of numerical crash simulations, it is not feasible for the engineers to analyze each area or component in detail, especially when these are not the core subject of investigation. In the field of occupant safety, the main explanatory objective is given by the signals of anthropometric test devices (ATD), as they are relevant for the fulfillment of legal regulations and consumer protection guidelines. Hence, this study proposes a data-driven methodology to automatically determine deviations in ATD behavior in a set of simulations and provide possible causes for the prevalence helping the engineer to understand simulations faster and to ensure quality.

• A Dedicated Forming Package LS-FORM for Stamping Simulation with LS-DYNA®

  Xinhai Zhu, Yuzhong Xiao, Jin Wu, Junyue Zhang, Yiquan Tang, Yi Xiao, Wei Ding (Livermore Software Technology, an ANSYS Company)

  One dedicated package providing the complete solution is always desired by LS-DYNA forming users. Being developed as a process-based package, LS-FORM achieves a seamless integration of pre-processing, LS-DYNA simulation and post-processing. An innovated tooling setup interface in pre-processing makes it easy to define complicated tool motions. The one-button submission provides the shortcut to the LS-DYNA solver to simulate a multi-stage stamping process. The post-processing module can perform a real-time analysis of the forming process by automatically chaining the multi-stage simulation results into a unified database. The user-friendly GUI, up-to-date graphic rendering and impressive stability will also make LS-FORM attractive to users.

• A Distributed Randle Circuit Model for Battery Abuse Simulations Using LS-DYNA ®

  Pierre L’Eplattenier and Iñaki Çaldichoury (LSTC), James Marcicki,Alexander Bartlett, Xiao Guang Yang, Valentina Mejia Min Zhu, Yijung Chen (Ford Research and Innovation Center)

  Battery abuse research and modeling, Spatially-resolved battery modeling, Electro-thermal battery modeling. A distributed Randle circuit model has been added to the electromagnetics (EM) module in LS-DYNA. This model implements so called “1 st order Randle circuits” connecting two vis-à-vis nodes on the positive and negative current collectors which define a unit cell. These circuits consist of a state-of-charge dependent voltage source, internal resistance, and RC loop for damping effects. They empirically model the electrochemical processes occurring between the current collectors during charge or discharge, such as electrochemical reactions, lithium transport through the electrodes and separator, and electron transport to reaction sites within the electrodes. The EM solver and Randle circuits are coupled to give the potential, current density, and heating distribution in the unit cell and connected conductors. The heat generation is transferred to the thermal solver, which then feeds back to the temperature dependent Randle circuit parameters. Several unit cells can be connected together either by a connecting mesh or by applying EM boundary conditions, hence forming a complete battery cell. Similarly, several cells can be coupled together to form a module. The main purpose of this model is the additional capability to model the electrical and thermal response to battery abuse scenarios, such as crash-induced crush. Depending on the local mechanical deformation occurring during a crush scenario, some of the Randle circuits can be replaced by a short resistance, hence triggering a local increase in the current flow and Joule heating which can lead to thermal runaway. The distributed Randle model is described, as well as how to set up a typical case in LS-DYNA. The process for obtaining inputs to the Randle card is demonstrated. Basic benchmarks with experimental results are presented.

• A Fabric Material Model with Stress Map Functionality in LS-DYNA

  T. Borrvall (DYNAmore Nordic), C. Ehle, T. Stratton (Autoliv OTC)

  Material 34 (MAT_FABRIC) in LS-DYNA is the material model of choice for fabrics when simulating airbag deployment in the automotive industry. Over the years, the model has been subjected to continuous robustness improvements and incorporation of important application features and today it comes in several forms and with an extensive set of parameters. The state-of-the-art modelling approach is to use the FORM=14 option which allows for specifying uniaxial stress-strain curves in the fabric’s warp and weft directions.

• A FAILURE CRITERION FOR POLYMERS AND SOFT BIOLOGICAL MATERIALS

  William W. Feng, John O. Hallquist - Livermore Software Technology Corp.

  A failure criterion, for polymers and soft biological materials subjected to very large deformation, is presented in this paper. The criterion is written in terms of the strain invariants in finite elasticity. Experimental tests for determining the failure criterion of a material and some numerical results from LS-DYNA are shown.

• A FE Modeling and Validation of Vehicle Rubber Mount Preloading and Impact Response

  Sae U. Park, Madhu R. Koka, Kevin R. Thomson, Jeffrey L. Robbins - DaimlerChrysler Corporation

  A variety of rubber mounts are being used for vehicles as isolators/dampers between body and frame, on the engine cradle, etc. It has been the prevalent CAE practice in the auto industry to evaluate the mounts’ high-speed vehicle crash response by the means of nonlinear spring/beam models. However, the simplified models carry a risk of generating incomplete and erroneous results, especially under very complex crash loadings due to the absence of component contact and failure criteria. To alleviate the shortcomings of the simplified mounts, this paper presents a FE representation of a detailed vehicle rubber mount coupled with failure criteria and initial bolt wrenching (preloading) using LS-DYNA, as well as test validation of those mounts.

• A Finite Element Analysis of Mid-Shaft Femoral Tolerance under Combined Axial-Bending Loading

  Costin Untaroiu, Dan Genovese, Johan Ivarsson, Jeff Crandall - University of Virginia

  Bone fractures occur frequently at mid-shaft femoral site during frontal and offset automotive crashes. Because these injuries are expensive, it is crucial to understand the injury mechanisms if this injury is to be prevented. The experimental investigation of femoral shaft tolerance under loading corresponding to real world accidents requires a challenging test setup that allows applying external loads in controlled conditions, mimics the boundary conditions of the femur, and measures the loads at the mid-shaft cross-section of the femur. In addition, the variability of mechanical and structural properties of the specimens complicates the determination of the injury tolerance of the femur under different loading conditions. A numerical alternative is presented in the current study. First, a subject specific finite element model of a femur is developed based on medical images. Then, the parameters of two material models frequently used to approximate the cortical bone properties are identified using the Successive Response Surface Methodology in the ranges reported in the literature. The objective function is defined based on the impact force data recorded during a three-point bending test and its corresponding numerical simulations. The polynomial meta-models implemented in LS-Opt converge at close values of the material parameters suggesting good performance of the heuristic design search in the current identification problem. The femoral tolerance at mid-shaft location is determined using a virtual test setup that applies combined axial –sagittal bending loading through an axial preload along the knee-hip line and a transversal impact load at the mid-shaft site along anterior-posterior or posterior-anterior directions. The femoral tolerance curves calculated based on external loads show sensitivity with respect to the impact direction of transversal load due to the initial curvature of the femur, but insignificant dependence on the material mode, or the failure criteria used for femoral cortical bone. In addition to suggesting a numerical approach that uses finite element simulations and optimization techniques to determine the injury tolerance of long bones, the results highlight the predominant role of the bending loading in a combined loading of the femur.

• A Finite Element Investigation Into the Continuous Induction Welding of Dissimilar Material Joints

  M. Duhovic, J. Hausmann (Institut für Verbundwerk­stoffe), P. L´Eplattenier, I. Caldichoury (LSTC)

  Continuous induction welding is an advanced material processing method with a very high potential of providing a flexible, fast and energy efficient means of joining together thermoplastic composites to themselves and metals and alloys. However, selection of the processing parameters and optimization of the process is very difficult as it involves the interaction of up to four differen t types of physics. In addition, many different material combinations including materials with low or high electrical conductivity, thermal conductivity and heat capacity, make the intuitive selection of processing parameters impossible. In this work, a si mulation test - bed, setup for the continuous induction welding of two material partners and their corresponding physics interactions is used to investigate the induction welding possibilities for several combinations of hybrid material joints.

• A Finite Element Model of THOR Mod Kit Dummy for Aerospace Impact Applications

  Costin D. Untaroiu, Jacob B. Putnam (Virginia Tech), Jeff T. Somers (Wyle Science)

  New spaceflight vehicles are currently being developed to transport crews to space by NASA and several commercial companies. During the launch, and landing phase, vehicle occupants are typically exposed to spinal and frontal loading. To reduce the risk of injuries during these common impact scenarios, NASA has begun research to develop new safety standards for spaceflight. The THOR, an advanced multi-directional crash test dummy, was chosen to evaluate occupant spacecraft safety due to its improved biofidelity. Recently, a series of modifications were completed by NHTSA to improve the bio-fidelity of the THOR dummy. The updated THOR Modification Kit (THOR-k) dummy was tested at Wright-Patterson (WP) Air Base in various impact configurations, including frontal and spinal loading. A computational finite element (FE) model of the THOR was developed in LS-DYNA® software and was recently updated to match the latest dummy modifications.

• A Finite Element Model of the Pelvis and Lower Limb for Automotive Impact Applications

  C. D. Untaroiu (Virginia Tech), J. Shin, N. Yue (University of Virginia), Y.-H. Kim, J.-E. Kim, A. W. Eberhardt (University of Alabama at Birmingham)

  A finite element (FE) model of the pelvis and lower limb was developed to improve understanding of injury mechanisms of the lower extremities during vehicle collisions and to aid in the design of injury countermeasures. The FE model was developed based on the reconstructed geometry of a male volunteer close to the anthropometry of a 50th percentile male and a commercial anatomical database. The model has more than 625,000 elements included in 285 distinct components (parts). The material and structural properties were selected based on a synthesis of current knowledge of the constitutive models for each tissue. The model was validated in seventeen loading conditions observed in frontal and side impact vehicle collisions. These validations include combined axial compression and bending (mid-shaft femur, distal third leg), compression/flexion/xversion/axial rotation (foot), and lateral loading (pelvis). In addition to very good predictions in terms of biomechanical response and injuries, the model showed stability at different severe loading conditions. Overall results obtained in the validation indicated improved biofidelity relative to previous FE models. The model may be used in future for improving the current injury criteria of lower extremity and anthropometric test devices. Furthermore, the present pelvis and lower limb was coupled together with other body region FE models into the state-of-art human FE model to be used in the field of automotive safety.

• A Full-Field Calibration Approach on Material Parameter Identification

  S. Cavariani, A. Scattina (Politecnico di Torino), S. Scalera (DYNAmore Italia), D. De Caro, M. M. Tedesco, F. D’Aiuto, S. Bianco, A. Luera, D. Ghisleri (C.R.F.), C. Ilg (DYNAmore)

  Nowadays the possibility to accurately simulate steel alloys is crucial to expect accurate results in crash analysis. Just as much as welding spots, innovative materials like polymers or composites more predictive steel material models are continually sought after throughout the industry. Complex models require a significant effort to calibrate them to the physical behaviour of the materials, but they can perform better. This work will evaluate and compare different techniques to characterize materials for finite element simulations.

• A Functional Bayesian Method for the Solution of Inverse Problems with Spatio-Temporal Parameters

  Zenon Medina-Cetina - International Centre for Geohazards / Norwegian Geotechnical Institute, Roger Ghanem, Amy L. Rechenmacher - University of Southern California

  A Functional Bayesian (FB) methodology is introduced for the calibration of constitutive parameters spatially distributed within a model. The probabilistic solution to the inverse problem consists of assimilating the uncertainty captured from the actual material responses into the material parameters. A case study is introduced to illustrate the applicability of the method, where a soil model built in LS-DYNA is parameterized using surface displacement fields read from stereo digital images taken during a series of triaxial tests performed under similar conditions. The implementation of the FB method yields probability density functions of the parameters and its corresponding correlation structure. The parameters field is efficiently sampled using the Polynomial Chaos Decomposition method (PC) which allows for spatial non-stationary and nonGaussian material representations. The posterior integration is performed via Markov Chain Monte Carlo techniques. Results show extended inferences about the material behaviour due to probabilistic description of the material variability.

• A General Damage Initiation and Evolution Model (DIEM) in LS-DYNA

  Thomas Borrvall, Thomas Johansson and Mikael Schill (DYNAmore Nordic AB), Johan Jergéus (Volvo Car Corporation), Kjell Mattiasson (Volvo Car Corporation and Chalmers University of Technology), Paul DuBois

  As the automotive industry is reducing the number of physical prototypes in favour of computer simulations during their design processes, a lot of demands is put on the accuracy of the virtual finite element models used for this purpose. In this context the mathematical modelling of fracture is of major importance and has been a field of intense research over the past 50 some years. There are numerous fracture models implemented in LS-DYNA, but as of tradition a fracture model is statically linked to the underlying constitutive model which in practice limits its usage to a single stage of the design process. Recently GISSMO [1,2,3] was introduced in an attempt to remedy this shortcoming by allowing the fracture model to be separated from the constitutive model, thus facilitating results from manufacturing simulations to be transferred to subsequent crash simulations. Behind GISSMO, the Damage Initiation and Evolution Model (DIEM) was developed in the same spirit and with similar capabilities, but this model has to the authors’ knowledge not been used extensively. The intention with this paper is to present this latter fracture model and compare it with GISSMO and, to some extent, with CrachFEM [4] to which it has superficial similarities.

• A Graphical User Interface for Simulating Resin-Transfer-Molding Combining LS-DYNA and OpenFOAM

  M. Wagner, M. Martins-Wagner (OTH Regensburg), A. Haufe, C. Liebold (DYNAmore)

  The paper describes parts of the joint research project Swim-RTM including several industrial and academic partners. Its goal is to combine LS-DYNA and the open-source fluid-dynamics solver OpenFOAM® to simulate the production process for fiber reinforced plastics, particularly the resin-transfer-molding (RTM) process. In this process, the layers of dry fabric (uni-directional or woven) are formed in the mold (draping) and then filled with liquid resin with high pressure at injection points.

• A gray-scale mapping method to consider locally varying properties for wood forming simulations

  C. Liebold (DYNAmore), D. Zerbst (German Aerospace Center), T. Gereke (TU Dresden), S. Clauß (Mercedes Benz)

  Automotive interior components in upper-class vehicles are often made of wood veneer sheets that are subject to a forming process [1]. Due to the anisotropy and inhomogeneity of the material caused by the development of annual rings during the growth of the tree, establishing a stable production process based on trial-and-error forming tests is time-consuming and costly [2]. Hence, numerical methods for simulating the forming process are in high demand to support the development of feasible trim part geometries. The key for reliable process simulations of wood-based materials is the consideration of the variability of material properties.

• A Grid-based Adaptive Scheme for the Three-Dimensional Forging and Extrusion Problems with the EFG Method

  H. S. Lu, C. T. Wu - Livermore Software Technology Corporation

  Procedures to adaptively refine meshes are emerging as an important tool for improving accuracy and efficiency in large deformation and fracture analysis. Comparing to the mesh- based adaptive method, the grid-based adaptive mesh-free method has several built-in advantages including naturally conforming in shape functions, smoothed interpolations in surface construction and state variable transfer, and the results are less sensitive to the unstructured grids. In this paper, a grid-based adaptive scheme is proposed for the Element Free Galerkin method in the large deformation analysis of three-dimensional forging and extrusion simulations. To precisely account for the effect of kernel functions during adaptive procedure, we consider the meshfree adaptivity in the framework of arbitrary Lagragian-Eulerian meshfree method with an operator-split time integration. A grid-based interpolation scheme adopted from the meshfree approximation is developed for the state variable transfer after mesh refinement to improve conservation and monotonic properties. Several industrial problems have been solved and compared to the existing numerical methods.

• A Heterogeneous Constitutive Model for Reinforced Carbon-Carbon using LS-DYNA

  Kelly S. Carney, Robert K. Goldberg, J. Michael Pereira - NASA Glenn Research Center, USA, Ryan S. Lee, Jeremie J. Albert - The Boeing Company

  Reinforced Carbon-Carbon (RCC) is a ceramic matrix, coated C/C composite used in the Space Shuttle’s thermal protection system. A constitutive model for RCC is presented that separates the coating and substrate within a multi-material shell element allowing for bending strains to be accurately computed during a finite element analysis. Version 971 of LS-DYNA contains a new shell element formulation that allows for different constitutive models through the thickness. The carbon substrate is modeled with an orthotropic damage model that was originally developed by Matzenmiller, and has been enhanced into MAT_RATE_SENSITIVE_COMPOSITE _FABRIC (MAT 158). The behavior of the silicon carbide coating is modeled using a new constitutive model that is now included in LS-DYNA as MAT_NONLINEAR_ELASTIC_TENSION_CRACKS (MAT 236). The composite model is used for debris impact analysis on the RCC structures, and good correlation is shown with impact test deflections and damage.

• A heuristic attempt to reduce transverse shear locking in fully integrated hexahedra with poor aspect ratio

  Dr. Thomas Borrvall - Engineering Research Nordic AB

  In an attempt to alleviate transverse shear locking in fully integrated hexahedra elements with poor aspect ratio, two new variants of solid element type 2 in LS-DYNA have been developed, implemented and tested on some critical problems. The approach is based on modifying the jacobian matrix in such a way that the spurious stiffness is reduced without affecting the true physical behavior of the element. The method is in a sense justified by means of a theoretical motivation, but above all indicated to be of practical use through some illustrating examples. The two new solid elements are termed type-1 and -2, where the latter is more rigorous but suffers from a higher computational expense, whereas solid element type-1 has an efficiency slightly worse than solid element type-2 for explicit analyses. However, all three element types are in that sense comparable for large scale implicit analyses.

• A heuristic attempt to reduce transverse shear locking in fully integrated hexahedra with poor aspect ratio

  Dr. Thomas Borrvall - Engineering Research Nordic AB

  In an attempt to alleviate transverse shear locking in fully integrated hexahedra elements with poor aspect ratio, two new variants of solid element type 2 in LS-DYNA have been developed, implemented and tested on some critical problems. The approach is based on modifying the jacobian matrix in such a way that the spurious stiffness is reduced without affecting the true physical behavior of the element. The method is in a sense justified by means of a theoretical motivation, but above all indicated to be of practical use through some illustrating examples. The two new solid elements are termed type-1 and -2, where the latter is more rigorous but suffers from a higher computational expense, whereas solid element type-1 has an efficiency slightly worse than solid element type-2 for explicit analyses. However, all three element types are in that sense comparable for large scale implicit analyses.

• A High Strain Rate Model with Failure for Ice in LS-DYNA

  Kelly S. Carney - NASA Glenn Research Center, David J. Benson - University of California, Paul Du Bois, Ryan Lee - The Boeing Company

  Modeling the high velocity impact of ice was a requirement in the safety calculations for the return-to-flight of the Space Shuttle on July 26, 2005. Ice, however, is not a common structural material and commercial finite element programs didn't have any appropriate models. A phenomenological model with failure was developed to match experimental ballistic tests. The model has a relatively small number of material constants, most of which have been measured experimentally. A description of the model and comparisons of calculations to experiments are presented.

• A Hosford-Based Orthotropic Plasticity Model in LS-DYNA

  F. Andrade (DYNAmore), T. Borrvall (DYNAmore Nordic), P. Du Bois (Consultant), M. Feucht (Daimler)

  n this contribution, we present a new orthotropic plasticity model available in LS-DYNA. Over the last decades, several orthotropic material models have been proposed in the literature where many of them have been implemented in LS-DYNA. Among these models, the model proposed by Barlat and Lian in 1989 [1], available in LS-DYNA in *MAT_036 [2], is a popular choice, especially in forming simulations. This model allows the user to define up to three R values (Lankford parameters) related to three material directions, namely 0°, 45° and 90° with respect to the rolling direction. Some years ago, the original orthotropic formulation by Barlat and Lian, available under *MAT_036 in LS-DYNA, was extended in such manner that the yield stress can depend on the different material directions. From a user point of view, this meant that up to five flow curves could be defined. Furthermore, up to five R values could also be used where these could be either constant or a function of the plastic strain. In *MAT_036, the extended model is activated by setting the flag HR to 7. However, the extended formulation incorporates the orthotropy in the yield stress as well. The consequence is that these two effects (orthotropy in the effective stress and also in the yield stress) concur against each other. For many materials, especially mild sheet steels, this aspect has often no major influence on the results. However, certain materials do exhibit quite dissimilar R values in the different material directions meanwhile the yield strength is very similar. This is, for instance, the case of many aluminum alloys. In such cases, the extended formulation available through HR=7 in *MAT_036 (or HOSF=0 in *MAT_036E) might lead to concave yield surfaces which, in turn, might lead to numerical instabilities. Therefore, a new option, issued through the flag HOSF, has been implemented in LS-DYNA in *MAT_036E. If HOSF is set to 1, a “Hosford-based” effective stress is used in yield function. This modification tends to alleviate the numerical instabilities observed in the model where the “Barlat-based” effective stress was used whenever the R values were very dissimilar. In a certain sense, the modification can be seen as a new plasticity model because in the new formulation the yield condition is not formulated using any information related to the R values but merely from the flow curves in the different directions. The R values are instead only used in the plastic flow rule. In this paper, we will show the advantages of such formulation as well as the results of the calibration of the material parameters for an aluminum sheet material. The results show that the simulation with the new material model can reproduce the strain fields captured in experiments through DIC very accurately.

• A Layer by Layer Approach for Simulating Residual Stresses in AM

  N. Strömberg (Örebro University); M. Schill (DYNAmore)

  Distortions and residual stresses developed during additive manufacturing (AM) might be so severe that the design does not meet tolerance requirements or even cracks and fail. Predictions of such distortions and residual stresses by finite element analysis are therefore preferable performed early during the design development in order to reduce such problems. One approach for this kind of analysis is to apply techniques from welding simulations letting the Goldak heat source moving over each layer of the material. However, this is computationally most costly and one might also argue how well this actually represent the AM process. We suggest to simplify this boundary condition to instead apply the heat layer by layer. We mean that this will represent the AM process as well as an approach of using the Goldak heat source and it is much more computational efficient than applying Goldak’s heat source. The model is simply obtained by slicing the geometry in several layers using an in-house script. Then, a volume heat source is applied layer by layer, where each layer is activated starting from the build plate until the final build layer. Sequentially thermomechanical analysis using LS-Dyna is applied, where the heat capacity, conductivity, Young’s modulus, Poisson’s ratio, expansion coefficient, yield stress, and the hardening modulus are given as functions of temperature. The classical heat equation and J2-plasticity with kinematic or isotropic hardening are adopted by using *MAT_THERMAL_CWM and *MAT_CWM, which makes the activation of the layers straight-forward using the ghost feature implemented in these material models. After all layers are activated and heated, a restart of cooling analysis is performed and, finally, the part is cut from the building plate using a third restart analysis. The approach is demonstrated for a benchmark of an open cylinder in Inconel 718 showing the development of distortions and residual stresses in all stages of the AM process from heating during building until the final cut from the build plate. We suggest that this benchmark can serve as an experimental setup in order to validate the suggested approach. This is discussed in the paper and is a topic for future work.

• A MATERIAL MODEL FOR TRANSVERSELY ANISOTROPIC CRUSHABLE FOAMS IN LS-DYNA

  Andreas Hirth - DaimlerChrysler, Paul Du Bois, Dr. Klaus Weimar - DYNAmore

  Recently new materials were introduced to enhance different aspects of automotive safety while minimizing the weight added to the vehicle. Such foams are no longer isotropic but typically show a preferred strong direction due to their manufacturing process. Different stress/ strain curves are obtained from material testing in different directions. A new material model was added to the LS-DYNA code in order to allow a correct numerical simulation of such materials. Ease-of-use was a primary concern in the development of this user-subroutine: we required stress/ strain curves from material testing to be directly usable as input parameters for the numerical model without conversion. The user-subroutine is implemented as MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM, Mat law 142 in LS-DYNA Version 960-1106. In this paper we summarize the background of the material law and illustrate some applications in the field of interior head-impact. The obvious advantage of incorporating such detail in the simulation lies in the numerical assessment of impacts that are slightly offset with respect to the foam’s primary strength direction.

• A Mesh Refinement Study on the Impact Response of a Shuttle Leading-Edge Panel Finite Element Simulation

  Karen E. Jackson, Edwin L. Fasanella - US Army Research Laboratory, VTD, Karen H. Lyle - NASA Langley Research Center, Regina L. Spellman - NASA Kennedy Space Center

  A study was performed to examine the influence of varying mesh density on an LS-DYNA simulation of a rectangular-shaped foam projectile impacting the space shuttle leading edge Panel 6. The shuttle leading-edge panels are fabricated of reinforced carbon-carbon (RCC) material. Nine cases were executed with all possible combinations of coarse, baseline, and fine meshes of the foam and panel. For each simulation, the same material properties and impact conditions were specified and only the mesh density was varied. In the baseline model, the shell elements representing the RCC panel are approximately 0.2-in. on edge, whereas the foam elements are about 0.5-in. on edge. The element nominal edge-length for the baseline panel was halved to create a fine panel (0.1-in. edge length) mesh and doubled to create a coarse panel (0.4-in. edge length) mesh. The element nominal edge- length of the baseline foam projectile was halved (0.25-in. edge length) to create a fine foam mesh and doubled (1.0- in. edge length) to create a coarse foam mesh. The initial impact velocity of the foam was 775 ft/s. The simulations were executed in LS-DYNA for 6 ms. Predicted structural deformations and time-history responses are compared for each simulation.

• A Mesh-free Analysis of Shell Structures

  C. T. Wu, Yong Guo - Livermore Software Technology Corporation, Hui-Ping Wang, Mark E. Botkin - General Motors

  A mesh-free formulation based on the Mindlin-Reissner shell theory for geometrical and material nonlinear analysis of shells is presented. In this mesh-free formulation, two projection methods are developed to generate the shell surface using the Lagrangian mesh-free interpolations. The updated Lagrangian theory underlying the co-rotational procedure is adopted for the local strain, stress and internal force updating. A local boundary integration method in conjunction with the selective reduced integration method is introduced to enforce the linear exactness and relieve shear locking. Both nonlinear static and dynamic analysis of shell structures with finite rotations are considered. Several numerical examples are presented to demonstrate the accuracy and applicability of the proposed formulation.

• A Meso-Macro Scale Method for Jointed Structures and Their Failure Analysis

  Wei Hu, CT Wu, Xiaofei Pan, Youcai Wu (Livermore Software Technology, LLC)

  As automotive industry moves rapidly towards electrified and digitalized world, the use of lightweight materials and new joining technologies becomes crucial to counteract the weight of electronic and autonomous equipment for energy efficiency as well as to maintain safety and performance. Numerical modeling the joined structures including their failure behavior has been a big challenge in the modern lightweight vehicle safety design. In this study, a two-scale method developed in LS-DYNA® is introduced for modeling jointed structures and their connection failure. In the meso-scale, a new particle stabilization method via a velocity smoothing algorithm is developed for simulating the large deformation and material failure of joint models. The meso-scale joint model characterizing the baseline of joint structure is bridging with macro-scale shell structures using an immerse approach. As a result, a topological coupling between solid and shell formulations is achieved without the need of matching discretization. This two-scale method facilitates the modeling of most connection failures in different joint models and minimizes human interactions with software. A crushing tube example is utilized to demonstrate the effectiveness and applicability of the present method in modeling the joined structures and failure behavior for the modern lightweight vehicle safety design.

• A Meta-model based Approach to Implement Variation Simulation for Sheet Metal Parts using Mesh Morphing Method

  H. Zheng, K. Upadhyay, F. Litwa (Mercedes-Benz), K. Paetzold (University of the German Federal Armed Forces Munich)

  The virtual process chain is an essential step for the sustainable digital transformation in the manufacturing industry. For the Body-In-White (BIW) sheet metal parts, the manufacturing joining simulation based on finite element method is used to simulate the joining processes in the body shop. The target is to predict the dimensional accuracy of assemblies after using different types of joining technologies. However, the assembly deviation is not only affected by the joining operations, but also by the initial part deviations. Therefore, an integration of geometrical variations in the joining simulation model is necessary to improve the prediction accuracy.

• A method for modifying the forming tool geometry in order to compensate for springback effects

  Anders Jernberg - Engineering Research Nordic AB, Sweden

  There is always a certain amount of springback deformation in a metal forming process. The high strength steel is becoming a more attractive choice for many applications when low weight of the structure is of importance. One major drawback with the high strength steel is that the springback deformation increased compared to low strength steel. All currently known techniques to reduce the springback deformation are used in tool design today, so it can be really hard to reduce the springback deformation further. The only possibility to obtain the desired geometry for the sheet after springback is to have a shape of the tool that is different than the desired final shape of the sheet. A method to modify the tool geometry in order to compensate for the springback effect is here presented. It is a heuristic method, based on the difference between the sheet after springback and the desired shape. No parameterisation of the tool geometry is needed. Since no parameters are describing the shape of the tool geometry, it can be modified in an arbitrary way without the restriction of the design space spanned by design parameter. The method is demonstrated on a doubly curved sheet and it is shown that the method gives a very fast convergence for the desired shape of the sheet. It is most likely that the method will work on a variety of different shapes. The method is applicable regardless of the yield strength of the sheet material, but most interesting are probably those materials which gives a large springback deformation, such as high strength steel and aluminium.

• A Methodology to Model the Statistical Fracture Behavior of Acrylic Glasses for Stochastic Simulation

  Marcel Berlinger, Stefan Kolling, Andreas Rühl (Technische Hochschule Mittelhessen), Jens Schneider (Technical University of Darmstadt)

  Acrylic glass made of PMMA bears great potential for automotive glazing. As a substitute for mineral glass, new freeform designs become possible with a simultaneous reduction of the structural weight. Under safety aspects of highly weight optimized components, a very precise knowledge of the material behavior is necessary since it is well known that PMMA is a material with high variability in its strength. In the present work, a methodology is proposed to determine the statistical probability distribution of fracture strains from experimental testing. Subsequently, a rate-dependent stochastic failure model is developed. By generation of uniformly distributed random numbers which represent the occurrence probability, *MAT_ADD_EROSION cards for LS-DYNA® are used, containing the tabulated fracture strains at different strain-rates. For stochastic simulation there are two possible procedures to apply the present model. The user provides a distinct probability quantile, e.g. 5 % occurrence probability, generates the corresponding *MAT_ADD_EROSION card and performs a worst-case simulation. Alternatively, the user generates a random set of probability quantiles, i.e. N values from zero to one, and performs N simulations. As an application, the last procedure is used in order to show the influence of a varying fracture strain on the head injury criterion (HIC) in validation tests on PMMA side windows. The example demonstrates the necessity of stochastic simulation for a reliable quantification of injury criteria in crashworthiness analysis.

• A Model for Process-Based Crash Simulation

  O.G. Lademo, T. Berstad, - SINTEF Materials and Chemistry, Norway., T. Tryland - Hydro Aluminium Structures, Norway., T. Furu - Hydro Aluminium R&D, Norway, O.S Hopperstad, M. Langseth - Norwegian University of Science and Technology

  Manufacturing of a bumper system from aluminium extrusions often involves series of forming operations performed in the soft W temper condition, and then artificially age-hardening the components to the material's peak hardness T6 condition. It is perceptible that correct numerical representation of the crash performance of the resulting systems must rely upon a geometry obtained from a model following the process route, i.e. including simulation of all major forming operations. However, the forming operations also result in an inhomogeneous evolution of some internal variables (among others the effective plastic strain) within the shaped components. Here, results from tensile tests reveal that plastic straining in W-temper results in a significant change of the hardening curves (alloy and ageing-dependent increase or decrease in strength) as a function of plastic pre- straining. In addition, the tests revealed that the plastic deformation led to a reduction of the elongation of the T6 specimens. These data were obtained by uniaxial stretching of plates in the W temper to different levels of plastic deformation, sub-sequent artificial ageing to obtain T6 characteristics, machining of uniaxial tensile test coupons and, finally, testing until failure. In the present work, these process effects have been included in a user-defined elasto-viscoplastic constitutive model incorporating a state-of-the-art anisotropic yield criterion, associated flow rule, non-linear isotropic and kinematic hardening rules, a strain-rate hardening rule as well as some ductile fracture criteria. To demonstrate and asses the modelling methodology, a 'through-process analysis' of the uniaxial tensile tests is performed. The pre-stretching of the plates in W temper is modelled with shell elements having an initial random Gauss- distributed thickness and stretched to different levels of plastic strain – comparable to the experimental ones - using the explicit solver of LS-DYNA. Then, uniaxial tensile specimens are trimmed from the deformed plates using the trimming option available in LS-DYNA. Next, strain dependent T6 properties are specified, after which the resulting specimens are stretched until instability and failure. Finally, the model assumptions are assessed by comparing engineering stress-strain curves obtained from the simulations and experiments.

• A Model for the Stochastic Fracture Behaviour of Glass

  Christopher Brokmann, Stefan Kolling (Technische Hochschule Mittelhessen)

  The failure of glass is caused by initial flaws that are induced during the manufacturing process. These micro-cracks are randomly distributed on the surface of glass, which is why failure is a random process and stress at failure is a non-deterministic parameter. In the present work, a model for the stochastic fracture behaviour of glass is proposed and implemented as a user subroutine in LS DYNA® for shell elements. Due to the stochastic fracture behaviour of glass, a large scattering can be expected when determining the head injury criteria (HIC) in the case of a pedestrian head impact on an automotive windscreen. In this case a high experimental effort would be necessary to evaluate the stochastic scattering. This can be reduced by numerical simulation using a stochastic failure model. The present model generates failure strengths out of a Weibull distribution obtained by coaxial ring-on-ring tests. The generated stresses are used to calculate initial crack lengths by recalculate the subcritical crack growth during experiments. These initial cracks slowly grow, i.e. subcritical, in dependence on the applied stress rate until the critical stress intensity is reached and failure occurs. In order to validate the model, coaxial ring-on-ring tests with different test setups are simulated and compared to experimental values and analytical solutions using the Weibull surface shift.

• A modified approach for simulating complex compound structures within early design steps

  Georg Gruber, Daniel Klein,Sandro Wartzack - University of Erlangen-Nuremberg

  Owing to increasing relevance of lightweight design the deployment of compound structures with their beneficial material characteristics becomes more and more important. These growing demands for lightweight design cannot be met by improving constructive details at the end of the development cycle. On the contrary already the early design steps have to be exploited adequately, since these steps offer the highest freedom of design. The present paper shows a modified approach for simulating complex compound structures adapted to the requirements of early design steps. The basic idea is overlapping several basic material models (characterized by a low amount of input parameters) within one finite shell formulation to describe any combination of material effects. The benefit of the approach is a more accurate simulation of complex compound structures with reduced modeling effort. A validation of this phenomenological material superposition approach is performed by opposing the results of virtual material tests to experimental results published in the literature.

• A MOOSE CRASH DUMMY FOR LS-DYNA

  Larsgunnar Nilsson, Anders Jernberg - Engineering Research Nordic AB

  The vehicle to moose impact constitutes a serious traffic problem in the Nordic Countries. Thus, in addition to the conventional requirements on crashworthiness, a Swedish car is also supposed to protect the occupants in the case of a moose impact. The Swedish National Road and Transport Research Institute (VTI) has developed a moose crash test dummy, which has shown to have a similar impact behaviour on the vehicle as a real moose. The main components of the test dummy are 36 rubber plates, but there are also various steel parts holding the pieces together. Due to the height of the moose, the main body will hit a normal size passenger car in the A-pillar and front window region. The legs will hit more frontal parts of the vehicle and make the moose body rotate. In a typical moose impact the A-pillars and the frontal roof are severely deformed into the passenger compartment. A FE-element model of the moose crash test dummy has been developed for LS-DYNA. The FE-model closely replicates all components of the physical dummy. About 30.000 elements are used for the model, which has a critical time step of about 1.5 microsecond. The FE-model of the moose is complete and only the contact interfaces between the moose and the vehicle need to be defined. Simulations of passenger car to moose impacts have been conducted and the results are evaluated and compared to physical test data.

• A new advanced visco-elastoplastic eight chain rubber model for LS-DYNA

  Dr. Tobias Olsson and Prof. Larsgunnar Nilsson - Engineering Research Nordic AB

  A new advanced eight chain rubber model has recently been implemented in LS-DYNA. The material is tailored for polymeric materials. The basic theory is taken from Arruda’s thesis from 1993 but it has been enhanced with advanced features such as the Mullins effect, viscoelasticity, plasticity and viscoplasticity. The Mullins effect is described by two different models: the first one is strain based and developed by Boyce in 2004 and the second is energy based and developed by Ogden and Roxburgh in 1999. The viscoelasticity is based on the general Maxwell theory with up to six Maxwell elements (a spring and a dashpot in series). There are three different viscoplasticity models implemented: a Norton model with two parameters, a G’Sell model with six parameters and a strain hardening model with four parameters. The plastic yield strength is based on the eight parameter Hill model. The material model has been used to simulate a compression test with a rubber specimen. The material parameters were obtained from inverse FE analys and parameter fitting using LS-OPT and a force-displacement data set. The result shows that this material model can predict rubber behaviour inline with experimental results.

• A New Approach to Contacts and Rigid Body Inter- actions in LS-DYNA

  Frederik Bengzon, Thomas Borrvall, Anders Jonsson, Gert Petersen

  Traditionally in LS-DYNA (almost) all contact definitions use a penalty formulation. This means that penetration in the contact is required to obtain a contact force between interacting entities. It is then up to the user to verify that the penetrations are small enough not to influence the results. The Mortar contacts [1], which have become the preferred choice for implicit analyses, is of penalty type. Also, the rigid walls (*RIGIDWALL) use a penalty method in implicit analyses. To find a good penalty stiffness setting may be problematic if solid elements (especially tetrahedra), or soft materials, such as rubber or plastic, are involved. It can be hard to find a good trade-off between reasonably small penetrations and implicit convergence.

• A New Concept on Stamping Die Surface Compensation

  Li Zhang, Jin Wu, Dajun Zhou - DaimlerChrysler Corporation, XinHai Zhu - Livermore Software Technology Corporation

  This paper classifies existing die compensation methods into two general categories, geometry-based method and springforward method. To meet the challenge of increased application of AHSS and its associated severe springback problems, we propose a new concept by using the tooling mesh of design intent as reference during compensation iterations. Incorporation of this concept into these two original methods enhances the efficiency and accuracy of compensated die surface. The enhanced geometric method minimizes the “wrinkle” effect caused by traditional methods done on the blank mesh. The enhanced springforward method improves the convergent rate to a specified tolerance. The proposed scheme can start compensations on a die with either design intent surfaces or already modified surfaces. It is also capable to incorporate actual panel scan data into compensation process to achieve high compensation accuracy.

• A new constitutive model for nitrogen austenitic stainless steel

  S. Fréchard, A. Lichtenberger, F. Rondot, N. Faderl - Institut Franco-Allemand de Recherches, France, Redjaïmia - Laboratoire de Science et Génie des surfaces, France, M. Adoum - CRIL, France

  Quasi-static, quasi-dynamic and dynamic compression tests have been performed on a nitrogen alloyed austenitic stainless steel. This alloy achieves a high hardening modulus and a good ductility at all strain rates. In addition, this steel is very sensitive to strain rate. The temperature sensitivity has been determined for temperatures varying between 20°C and 400°C. Microstructural analysis has been performed on samples subjected to different loads in order to relate the microstructure to the material behaviour. Johnson-Cook and Zerilli-Armstrong models have been selected to fit the experimental data into constitutive equations. These models are unable to reproduce the behaviour of this type of steel over the complete range of tests. A new constitutive model that better fits all the experimental data at different strain, strain rate and temperature has been determined. This empirical model supposes that the influence of the main parameters is independent. Single Taylor impact tests have been realized to validate the models. Live observations of the specimen during impact have been achieved using a special CCD camera set-up. The overall profiles at different times were compared to numerical predictions performed with LS-DYNA.

• A New Development in Pedestrian Safety: The FLEX-PLI GTR LS-DYNA Model

  Chirag S. Shah, Fuchun Zhu, Roel Van De Velde, Robert Kant - First Technology Safety Systems

  The lower limb is one of the most frequently injured body regions in crashes involving pedestrians. A biofidelic FLEXible-Pedestrian Legform Impactor Global Technical Regulations (FLEX-PLI GTR) device has been developed under directions of the Flex-PLI Technical Evaluation Group (FLEX-PLI TEG). First Technology Safety Systems (FTSS) is developing a LS-DYNA model in addition to the hardware counterpart. The FLEX-PLI GTR is the latest development and successor of the earlier GT version. The FLEX-PLI GTR device has three regions: femur, knee and tibia. Outer rubber and neoprene foam layers represent the skin and flesh. The femur and tibia regions are segmental to achieve flexible bending behavior representing human like responses during pedestrian crashes. The central bone cores of the tibia and femur have bending moment measuring capabilities at several locations. The knee region has ligament elongations measuring capabilities to be used as injury criteria in regulations. This paper documents the development and dynamic validations of the FTSS FLEX-PLI GTR LS-DYNA model. The model geometry and inertia properties are obtained from available drawings and hardware. The model connectivity and structural integrity are inspected by experiments and verified against hardware. The model material properties are implemented from material test data. The model is then validated against dynamic calibration test for FLEX-PLI assembly without outer skin, and a full legform test against a flat rigid impactor (called inverse test). The femur and tibia bone bending moments and knee ligament elongations from the model output are compared to test data to evaluate model performance and injury predictability. The FTSS FLEX-PLI GTR LS-DYNA model revealed very promising performance in all validation cases and can be potentially used in future pedestrian safety regulations. The model has a 0.85 micro second time step and was found to be very cost effective (in terms of CPU times) and reliable for pedestrian safety simulations.

• A New Eigensolver for High Performance NVH Analysis: MCMS (Multi-Level Component Mode Synthesis)

  Prof. K. Chang-Wan (Konkuk University); R. Grimes (LSTC)

  NVH (Noise, Vibration, and Harshness) problem is one of the most important targets for comfortable and quiet product design. Especially, in automobile industry, as the degrees of freedom of NVH automobile FE model increases, from millions of degrees of freedom to tens or hundreds millions of degrees freedom, the computational time for NVH analysis becomes serious bottle neck in automobile design and analysis process. Therefore, it has been strongly desired to reduce the computational time of eigenvalue problem analysis, which is the most important part of NVH analysis. In early 2000, the Automated Multi-Level Substructuring (AMLS) method was developed to reduce the computational costs of NVH analysis by the group of University of Texas at Austin, in which author of this paper is also involved in the development of AMLS method as well as Fast Frequency Response Analysis(FFRA) method. As the AMLS method provide significant contributions on automobile NVH analysis, many CAE softwares such as NASTRAN, ABAQUS, Hyperworks released new feature which is similar to AMLS. LSTC has developed a new eigensolver, MCMS(Multi-level Component Mode Synthesis). MCMS generally produces approximate eigensolutions that are less accurate than those computed by Lanczos method, but the error can be tolerated in automobile NVH applications

• A New Eikonal Solver for Cardiac Electrophysiology in LS-DYNA

  Pierre L’Eplattenier, Karim El Houari, Olivier Crabbe, Francesc Levrero-Florencio

  Heart disease is among the leading causes of death in the western countries; hence, a deeper understanding of cardiac functioning will provide important insights for engineers and clinicians in treating cardiac pathologies. In this paper we will concentrate on electrophysiology (EP), which describes the propagation of the cell transmembrane potential in the heart. In LS-DYNA, EP can be coupled with solid and fluid mechanics for a multiphysics simulation of the heart, but pure EP is also often used to investigate complex phenomena such as cardiac arrhythmia or fibrillations. The gold standard model for EP is the “bi-domain” model, along with the slightly simplified “mono-domain”. These were introduced in LS-DYNA a few years ago [1]. They give very accurate predictions, but the associated computational expenses are significant, which can be an issue for patient-specific predictions, for example, cardiac activation patterns for complex procedures such as cardiac resynchronization therapy (CRT).

• A New Failure Criterion for Laminated Safety Glass

  C. Alter, S. Kolling (TH Mittelhessen); J. Schneider (TU Darmstadt)

  The prediction of the head injurie criterion (HIC) for pedestrian protection in automotive applications is still a great challenge. In particular, the simulation of the head impact on windshields requires a reliable FE-modelling technique as well as predictive material laws including the constitutive behaviour up to fracture. In the present work, a new failure criterion for laminated safety glass under low velocity impact is presented. The model is implemented as a user defined material model for shell elements in LS-DYNA. In order to represent the stress intensity in the vicinity zone of a crack tip, a mixture of the element erosion technique and a decrease of strength in the direction of cracks is considered. By that there is no need to determine the current stress intensity factor. The used failure prediction is similar to a major stress criterion and the fracture strength depends on the stress rate and, in addition, on the fracture state of the neighboring elements. The basic strength is derived from the first region of the crack-velocity dependency which is approximated by an empirical power law. The reduction of element strength in crack direction depends on the element size which allows the use of a regular, coarse mesh. Experimental results of head impact tests under different configurations are used for the validation of the present model.

• A New Feature to Model Shell-Like Structures with Stacked Elements

  T. Erhart (DYNAmore)

  A computational method for the numerical simulation of stacked shell-like structures will be presented. These types of plane load-bearing components possess a thickness which is small compared to its other (in-plane) dimensions and physical properties vary in thickness direction in distinct layers. Such materials are made from two or more constituent materials with different physical or chemical properties, that when combined, produce a material with characteristics different from the individual components. The individual components remain separate and distinct within the finished structure.

• A New Heat Transfer Capability Between CPM Gas and Its Surroundings

  Sheng Peng (LSTC)

  Corpuscular particle method (CPM) was developed for airbag deployment simulations. It took into account specifics like airbag folding technique, vent hole design, and interaction between discretized gas flow and airbag fabric to capture the effects of dummy impact on airbags, both fully inflated and out-of-position. It’s numerically very robust and the particle-based nature leads to elegant treatment of venting, porous leakage and gas mixing. Users find novel situations to apply the method and oftentimes new features are needed to better support these scenarios. Among these is the need of more comprehensive treatment of heat transfer. Based on kinetic molecular theory, CPM model behavior is heavily influenced by heat transfer. Yet, a full-blown coupled thermal analysis might not always be viable for a refined model. To enable modeling of heat transfer just in the neighboring structures of the CPM gas can provide a solution to this quandary. The design and implementation status will be discussed. Some other recent advances in CPM in LS-DYNA® will also be discussed. For example, airbag integrity checking reports to the user hard-to-discover abnormality in the airbag structure definitions in the input phase.

• A New Impact Scenario for P-V Tram Certification

  M. Anghileri, L. Castelletti, M. Pirola, F. Pistochini, S. Raiti- Politecnico di Milano, Italia

  Tram crashworthiness is getting a more and more demanding issue. Simulations carried out to verify that the new tram AnsaldoBreda Sirio-Milano fulfils the prEN 15227 requirements for certification are here described. Besides a new impact scenario with characteristics closer to trams accidents is proposed. Structural enhancements so that the tram fulfils also the more severe impact condition of the new scenario are introduced.

• A New Keyword to Apply Moving Temperature Boundary Conditions and its Application in Fused Filament Fabrication

  Jinglin Zheng, Xinhai Zhu (Livermore Software Technology, an ANSYS company), Danielle Zeng (Ford Motor Company)

  This paper introduces a new keyword, *BOUNDARY_TEMPERATURE_TRAJECTORY, which is capable of applying a prescribed temperature boundary condition within a specified volume which moves along a designated path at a given speed. Combined with LS DYNA®’s computational welding material model, it is able to simulate the process of extruding and depositing melted material onto the build platform, such as the process of fused filament fabrication. An example of printing a dog-bone-shaped plastic part is given to demonstrate the usage of this keyword. The simulation result agrees very well with experimentally measured local temperature histories, which demonstrates the validity and accuracy of this simulation approach.

• A New Method for CrachFEM ‘Damage’ Parameter Calculation & Transfer from Autoform to LS-Dyna

  Michael Buckley - Jaguar Land Rover, Mike Selig - Autoform Development GmbH, Martin Oehm - MATFEM

• A New Method for Efficient Global Optimization of Large Systems Using Sub-models HEEDS COMPOSE Demonstrated on a Crash Optimization Problem

  N. Chase, R. Sidhu, R. Averill (Red Cedar Technology)

  Executing full vehicle finite element simulations can be very time consuming and expensive. Compound this with the large number of evaluations required for crash optimization problems due to their complicated design landscapes, and optimization of full vehicle crash simulations becomes very computationally expensive and difficult. An ideal solution is to reduce the full vehicle down to a manageable sub-model which runs significantly quicker while maintaining the boundary constraints as if utilizing the full vehicle model. The optimization process can then be managed with this sub-model while achieving significant improvements in computational requirements. This paper will demonstrate how to optimize the a-pillar, b-pillar, roof rail, rocker, front header, and roof bow components of a car for roof crush, utilizing Ultra High Strength materials. In addition to the gauge of the individual structural components, a soft zone trigger and its location within the b-pillar are introduced as design variables. LS-DYNA® is utilized as the simulation tool with the new COMPOSE (COMPonent Optimization in a System Environment) feature within the HEEDS-MDO optimization software utilized to perform the optimization. COMPOSE is a new module that enables the use of a sub-model for optimization in a way that significantly reduces the overall optimization time while encouraging the interactions of the optimal subsystem with the global model to be consistently maintained. This creates a design that gives a similar high performance in the global model as was found in the sub-model. It is shown here that the use of COMPOSE can significantly decrease the design time for finding high performing designs for the roof crush optimization, over a traditional global optimization approach. In addition, it is shown that performing an optimization on the sub-system level by using the original boundary conditions from the global model is not a robust approach for this optimization. The study shows that to take advantage of the reduced runtime in the sub-system model, the COMPOSE technology provides a robust solution for efficient optimization of the system.

• A New Method for the Structural Optimization of Product Families

  Larsgunnar Nilsson - Engineering Research Nordic AB, Michael Öman - Scania CV AB

  This paper discusses the problem of structural optimization of product families subjected to multiple load cases, evaluated by computationally costly finite element analysis. Product families generally have a complex composition of shared components that makes individual product optimization difficult as the relation between the shared variables is not always intuitive. More optimal is to treat the problem as a product family optimization problem. For product families subjected to multiple and computationally costly crash loads, however, the optimization problem takes too long time to solve with traditional methods. Therefore, a new optimization algorithm is presented that decomposes the family problem into sub-problems and iteratively reduces the number of sub-problems, decouple and solve them.

• A New Model Reduction Method for Vehicle Crash Simulation

  Shinya Hayashi, Shinya Hiroi, Norio Shimizu

  When major design changes are required to satisfy product performance late in the development process, significant cost and time are required to implement them. This is a particular problem in automotive development which requires a large amount time and cost. To alleviate this, automotive manufacturers have adopted the concept of "front-loading" to identify problems early-on in the development process. “Front-loading” is defined as "the distribution of development costs or time in large proportions in the early stages of the design process”.

• A New Modelling for Damage Initiation and Propagation of Randomly-Oriented Thermoplastic Composites

  K. Saito, M. Nishi (JSOL), S. Hayashi, M. Kan (Honda R&D)

  A new method to model damage properties of Randomly-Oriented Thermoplastic Composites (RO-FRTP) was proposed for finite element analysis (FEA). The materials are composites of thin sheets in which carbon fibers of approximately one inch in length are distributed randomly in thermoplastics resin matrix. While their material properties are intrinsically isotropic in plane from a macro perspective, RO-FRTP have complex nature of damage initiation and progression that depends on the deformation mode. In this study, the damage model that based on Continuum Damage Mechanics (CDM) was developed and the modelling method with 3D shell element for RO-FRTP was proposed. The multifunctional feature of *MAT_ADD_GENERALIZED_DAMAGE in LS-DYNA® has been utilized in order to reproduce damage properties of the material. Furthermore, several numerical studies are conducted and compared to experiments for the purpose of validation of the modelling method. Simulation results show that the modelling method can capture complex damage characteristics of the material in detail and predict deformation of structures accurately.

• A New Simulation Method for Airbags With Multiple Compartments (Adaptive Euler Domains)

  R.S. Sadeghi, W.A. van der Veen - MSC.Software Corporation

  The paper presents a new simulation method for airbags with multiple compartments. In recent years many accidents happened with passengers that were out of position (OOP) when their airbag deployed. Therefore new safety regulations have come into effect in the USA and an airbag now has to meet several requirements that concern out of positioning. In meeting these requirements simulations of deploying airbags are very useful and are widely used. In OOP the airbag hits the passenger when it is still deploying and the pressure field is far from uniform and so there is a complicated interaction between gas flow and the deploying membrane. This calls for an analysis in which the dynamics of the airbag membrane is coupled with a CFD (Computational Fluid Dynamics) solver. To weaken the frontal blow, an airbag with multiple compartments is sometimes used. The idea is to divert the gas stream in the airbag away from the frontal direction into sideways directions. Since these airbags especially need to operate well in OOP setting the CFD approach is required. The paper presents a new method to simulate a multi-compartment airbag in which each compartment is modeled by the CFD approach and each with a separate Euler domain. Before discussing multi-compartment simulations, we present background on simulations for one airbag using one Euler mesh. In these simulations the gas flow is described by the conservation laws of mass, momentum and energy. Also modeling of the interaction between CFD solver and airbag membrane solver is discussed. The conservation laws are applied to the 3D objects that are formed by taking an Euler element and cutting away everything that is outside the airbag surface. The boundary of this 3D object is in general a multi-faceted surface that consists of: (1) Polygons that connect an Euler element to another Euler element and that are called faces. (2) Polygons that connect Euler elements to the airbag surface, and are called polpacks. In the conservation laws several surface integrals occur. Many of these integrals have to do with transport and are computed by running over faces and polpacks. This gives rise to mass being transported across faces. In most cases there is no transport across polpacks since they are part of the airbag surface. For multi-compartment simulations we have to consider multiple Euler domains. Each Euler domain models one airbag. Communication between the airbags proceeds via the holes that connect one airbag with the other. Holes are modeled as a piece of airbag surface that is fully porous. Given that the largest possible timestep depends on the mesh size, each Euler domain could be advanced with a specific timestep. This would require subcycling. For the multi-compartment application mesh sizes are expected to be of comparable magnitude and all Euler meshes are advanced with the same timestep.

• A New Strain Rate Dependent Spot Weld Model for Automotive Crash Applications

  Dr. P.K.C. Wood - University of Warwick, Mr. M.A. Buckley - Jaguar and Land Rover, Dr. B. Walker - Ove Arup and Partners, Mr. T. Dutton - Dutton Simulation

  New spot weld failure models in a range of sheet steels have been developed for use in the virtual testing of automotive crash structures to ensure compliance to international safety requirements. The desire to balance the cost to develop the data input to spot weld failure models and their capability to predict failure in simulation tools is central to the method. Full vehicle crash simulations suggest confidence in the predictive capability of the models. This paper describes a strain rate dependent spot weld failure model for use with hexahedron (solid) elements. A spot weld may comprise one, or a cluster of four, eight or sixteen solid elements. The enhanced functional capabilities of the new spot weld model allow a force-based failure for a solid element in which maximum shear force and tension force may be a function of strain rate, and each may each be defined uniquely using a load curve. Further the strength hardening effect at higher strain rate may be defined for the solid element using a simple constitutive expression which relates the properties of the spot weld to plastic strain rate. The new model has been programmed and tested in the finite element software code LS-DYNA®. The results suggest the new spot weld model is capable of reproducing the quasi-static and high rate physical test responses with a high degree of accuracy.

• A New Way for Multi-piece and Multi-hit Fragment Impact Simulation Using LS-DYNA

  Xudong Xin - Karagozian and Case

  The kinetic feature of weapon fragment is many small masses traveling at extremely high velocities and scattering radially from the explosion center. To simplify the fragment impact analysis, people often convert the fragment momentum into a triangular pressure load with very high magnitude and very short duration, and apply the load directly onto the target. This method may over- or under-predict the impact response due to the complicacy of fragment behaviors such as embedment, perforation and ricochet. It might encounter more difficult situation when involving multi-layer impact and penetration problem. This paper proposes a new method for fragment simulation using the contact technique provided in LS-DYNA. A program was developed which can automatically generate the LS-DYNA keyword input of node, part, initial velocity and contact surface cards for multiple pieces and sets of fragments, based on the given information about mass, location, velocity of each fragment, and other user-defined parameters. This method can be applied not only on multi-piece fragment impact simulation, but also on multi-hit problem in a realistic way. Examples of fragment impact on structure are demonstrated.

• A New Way for the Adaption of Inverse Identified GTN-Parameters to Bending Processes

  Ioannis Tsoupis, Marion Merklein (Friedrich-Alexander-Universität Erlangen-Nürnberg)

  One major challenge in metal forming exists in sheet metal bending of modern lightweight materials like high‑strength low-alloyed steels (HSLA), since conventional methods of predicting failure in numerical simulation, like the forming limit diagram (FLD), can generally not be applied to bending processes. Moreover, fracture mechanisms are mainly depending on the microstructure, which is very fine-grained in HSLA steels composed with different alloying elements compared to established mild steels. Consequently the damage and failure behaviour of HSLA steels are changing. Especially for small curvature bending processes characterised by high gradients of strain and stress over the sheet thickness other failure criteria than the FLD have to be utilised. Within this paper a numerical study of the micromechanical based damage model Gurson-Tvergaard-Needleman (GTN, *MAT_120) is performed in LS-DYNA®, in order to realise an effective adaptability of the model for bending operations on HSLA steels. The material dependent damage parameters are determined by commonly used methodology of inverse numerical identification re-calculating the uniaxial tensile test. The minimisation of the mean squared error (MSE) of experimental and numerical global load displacement curves is realised by an optimisation algorithm using commercial software LS‑OPT®. For the adaption of the GTN-Model to the bending operation a strain-based calibration method is developed. This method is based on the comparison and adaption of the numerically calculated and the experimentally measured deformation field on the outer surface of the bent specimen. In this context the parameters are systematically varied again in the optimisation software LS-OPT. Their influence on the strain and damage evolution is analysed and discussed. On the one hand it is shown that it is possible to represent the strain evolution by adapting only one parameter instead of all parameters of the model and thus reducing the modelling effort for the user. On the other hand a big effect on the damage evolution and distribution can be identified.

• A Next Generation Software Platform for LS-DYNA Modeling and Configurable Vertical Application Development

  H. Ouyang, Tim Palmer, Q. He - Engineering Technology Associates, Inc.

  Finite element modeling tools have undergone a transformation in recent years. These tools have been made easier to use, configurable for vertical applications and able to interact with outside applications. Such software needs to not only efficiently create models, but are also expected to interact with other software tools, be configurable and anticipate the future needs of users by being able to extend the users ability to assimilate models and other data efficiently into an LS-DYNA environment. Using the heritage of a stable, well-featured finite element modeling software, ETA has developed a new software platform to create finite element modeling software that meets the challenges of today’s users, both from an infrastructure and a data management standpoint. This will offer users an opportunity to create, share and manage models using standardized interfaces, scripting tools and both standardized and user-defined processes. This paper will present the opportunities that this new platform will offer users and the future of modeling tools that empower users of optimization and synchronous design tools.

• A Next Generation Software Platform for LS-DYNA Modeling and Configurable Vertical Application Development

  H. Ouyang, Tim Palmer, Q. He - Engineering Technology Associates, Inc.

  Finite element modeling tools have undergone a transformation in recent years. These tools have been made easier to use, configurable for vertical applications and able to interact with outside applications. Such software needs to not only efficiently create models, but are also expected to interact with other software tools, be configurable and anticipate the future needs of users by being able to extend the users ability to assimilate models and other data efficiently into an LS-DYNA environment. Using the heritage of a stable, well-featured finite element modeling software, ETA has developed a new software platform to create finite element modeling software that meets the challenges of today’s users, both from an infrastructure and a data management standpoint. This will offer users an opportunity to create, share and manage models using standardized interfaces, scripting tools and both standardized and user-defined processes. This paper will present the opportunities that this new platform will offer users and the future of modeling tools that empower users of optimization and synchronous design tools.

• A Non-linear Strain-rate Micro-mechanical Composite Material Model for Impact Problems

  Ala Tabiei, Sandeep Medikonda, Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA

  A micro-mechanical composite material model is developed to simulate the behavior of uni-directional composites under impact loading conditions in LS-DYNA®. The non-linear strain-rate and pressure dependency in the composite material model is accounted by the resin, which uses previously developed state-variable viscoplastic equations. These equations have been originally developed for metals, however are modified to account for the significant contributions of hydrostatic stresses typically observed in polymers. The material model also uses a continuum damage mechanics (CDM) based failure model to incorporate the progressive post-failure behavior. A set of Weibull distribution functions are used to quantify this behavior and a methodology of assigning physical significance to the choice of damage/softening parameters used in these functions is presented. The impact response of composite laminate plates has been simulated and compared to the experiments. In addition, the effect of hydrostatic stresses on impact problems has been further studied in detail. It has been observed that the predicted results compare favorably to the experiments.

• A Non-orthogonal Material Model of Woven Composites in the Preforming Process

  Weizhao Zhang, Huaqing Ren, Biao Liang, Jian Cao, Northwestern University, Evanston, IL, USA;, Danielle Zeng, Xuming Su, Jeffrey Dahl, Ford Motor Company, Dearborn, MI, USA;, Mansour Mirdamadi, Dow Chemical Company, Midland, MI, USA, dQiangsheng Zhao, Livermore Software Technology Corporation, Livermore, CA, USA

  Woven composites are considered as a promising material choice for lightweight applications. The new LS-DYNA® material model MAT_COMPRM (MAT_293) that can decouple the strong tension and weak shear behavior of the woven composite under large shear deformation is developed for simulating the preforming of woven composites. The tension, shear and compression moduli in the model are calibrated using the tension, bias-extension and bending experiments, respectively. The interaction between the composite layers is characterized by a sliding test. Finally, the material model is validated by a double dome study.

• A novel transversely-isotropic 3D elastic-viscoplastic constitutive law for modeling fiber matrix composites

  M. Vogler, R. Rolfes - Leibniz University Hannover, F.X.C. Andrade - University of Porto, J.Schöpfer - Daimler AG, S. Kolling - German Institute for Polymers (DKI)

  A transversely isotropic elastic-viscoplastic constitutive law with a novel 3D failure crite- rion is presented, addressing high pressure effects, strain rate sensitivity in yielding and failure and volumetric plastic strain. The constitutive equations are derived in the frame- work of transversely-isotropic invariants, which allow for a coordinate system independent formulation and an easy parameter identification. Triaxiality dependent non-linearities are taken into account and entirely different yielding behavior under uniaxial/biaxial compression, uniaxial/biaxial tension and under in-plane/transverse shear stress states is addressed. Hardening curves for each loading state can easily be input either via tabu- lated data or optionally by use of a three parameter power law. Lateral plastic straining due to volumetric plastic compression and dilatation is load path dependent as well. In order to control the lateral plastic straining in each stress state, a non-associated flow rule, assuming a plastic potential which gives the direction of the plastic flow is introduced. The applicability of this novel material law is shown by two examples.The first one is a short fiber reinforced thermoplastic PA6GF60, the second one adresses off-axis tensile and compression tests of a unidirectional carbon-epoxy IM7-8552, which is widely used in aircraft industry. For PA6GF60, a complete test setup for characterizing the novel transversely isotropic yield surface is used for validation. All test cases are simulated and compared with these experiments. The sensitivity of the plastic Poisson coefficient and the influence on the simulated load displacement curves are discussed. Strain rate effects are obtained from dynamic uniaxial tensile tests and are considered by a viscoplas- tic approach. Unidirectional carbon-epoxy IM7-8552 reveal pronounced yielding under combined shear- compression loadings as it is observed in off-axis compression tests. Fur- thermore, the glass transition temperature of epoxy resin drops from above 200◦ C to operating temperature in the presence of high pressures. This results in a change of me- chanical properties, effecting the elastic parameters as well as the yielding behavior.This change of mechanical properties and the pronounced non-linear behavior in the presence of high pressure due to matrix yielding can be modeled properly with this new approach.

• A Numerical Investigation for Rock Fall Impact Behavior of Pithead of Tunnel with Falling Weight Impact Loading

  Abdul Qadir Bhatti, Khaliq U Rehman Shad - National University of Sciences & Technology NUST, Pakistan, Norimitsu Kishi - Muroran Institute of Technology, Muroran

  In order to establish a rational impact resistant design procedure for Arch type rock-shelter based on not only allowable stress design but also on ultimate state design and/or performance based design method, impact resistant capacity and/or maximum input impact energy for the RC structures must be clearly estimated. At present, the RC structures have been designed statically based on allowable stress design method. Here, maximum input impact energy for reaching ultimate state was numerically estimated by means of three-dimensional elasto-plastic finite element method for existing real arch-type RC rock-shelters with sand-cushion and EPS layer under falling heavy- weight impact loading. In this numerical analysis, solid elements were employed for concrete, falling heavy-weight and sand-cushion, and beam elements for rebar. Drucker-Prager and rebar yield criteria were used as material constitutive law for concrete and rebar, respectively. Cracks were estimated by allowing tensile stress cut-off at reaching at the tensile strength. In this paper, weight impact force, total axial force at the side-walls, displacement wave at the loading point, and crack patterns of the shelter at the time occurring of the maximum displacement are output. The results obtained from this study are as follows; 1). About twice the bending moment are generated at the edge as compare to the centre of falling weight in the direction of road axis. 2) It was observed that maximum response generation time of the bending moment and shear force is different. 3) When three layer buffer structure is set up in the tunnel pithead part, the sectional force can be decreased to about 1/2 to 1/5 in the mid-span compared with the case for sand cushion. Keywords: Pithead of tunnel; Three-layered absorbing system; Transmitted impact force; elasto-plastic response

• A Numerical Investigation into the Injury Potential of Three-year-old Children Seated in Forward Facing Child Safety Seats During Side Impact Crashes in Far Side Configurations

  Qian Wang, Tanya Kapoor, William Altenhof - University of Windsor, Andrew Howard - The Hospital for Sick Children

  This research focuses on the injury potential of children seated in forward facing child restraint seats during side impact crashes. Side dynamic sled tests were conducted by NHTSA using the existing FMVSS 213 seat fixture oriented at both 90° and 45° relative to the motion of the sled buck. A half sine pulse and a scaled FMVSS 213 pulse were used in the tests. All the tests were conducted at a test velocity of 32 km/h (20 mph) and a peak acceleration of 17 g’s. A forward-facing Hybrid III 3-year-old child dummy positioned in a child restraint seat (CRS) with LATCH and the top tether in far side configurations were used in the tests. Details of the sled tests were stated in FMVSS 213 ANPRM. A finite element model of the child restraint seat was developed using FEMB for simulation in LS- DYNA. The child seat model, which included all CAD surfaces provided by Century/Graco Corporation, was fully deformable and was previously validated for frontal impacts. Three side impact simulations were completed for data comparison. (i) using the half sine acceleration pulse with the seat oriented at 90° relative to the motion of the sled, (ii) using the half sine acceleration pulse with the seat oriented at 45° relative to the motion of the sled, and (iii) using scaled FMVSS 213 acceleration pulse with the seat oriented at 90° relative to the motion of the sled. Validation of the numerical model was completed by comparing the head injury criteria (HIC) values and chest accelerations from the experimental and numerical tests. The simulation results were generally in good agreement to the experimental observations. Further studies were conducted to confine lateral movement of the dummy’s head by adding energy absorbing foam blocks in the head region of the CRS. It was observed from the simulation results that foam padding was effective in reducing the injury potential of the child dummy.

• A Numerical Investigation into HIC and Nij of Children for Forward and Rearward Facing Configurations in a Child Restraint System

  William Altenhof, Rita Turchi - University of Windsor

  This study explores the various differences in potential for injury in 3-year-old children in the case of a frontal collision. A crash analysis between forward and rearward facing children, both restrained in a five-point child restraint, was performed using numerical simulation methods. This comparison was carried out by conducting numerical simulations of these situations using the criteria outlined in FMVSS 213. The injuries that were assessed included neck and head injury, as those types of injuries can be the most devastating and sometimes fatal. In this study, it was determined that when the 3-year-old Hybrid III dummy model is in a rearward facing position, the child sustains less neck loads and head accelerations than the forward facing dummy model. In other words, a 3- year-old child would sustain lower levels of Neck Injury Criteria (Nij) and Head Injury Criteria (HIC). In fact, the difference in the Nij values is quite significant. In North America, the standard for restraining young children states that for a child under the age of 12 months, the child should be restrained in a child seat facing the rear of the vehicle. After 12 months of age, the child can then face forward. This study has opened the forum to debate if this standard should be reconsidered as to save the lives of thousands of children being injured and dying unnecessarily at the hands of vehicle collisions.

• A Numerical Investigation of Human Biomechanical Response under Vertical Loading Using Dummy and Human Finite Element Models

  Costin D. Untaroiu, Jacob Putnam (Virginia Tech)

  The safety of aerospace transport for both fixed and rotary wing aircraft is evaluated primarily through testing of anthropometric test devices (ATDs), commonly known as crash test dummies. While the majority of the ATDs were certified under automotive horizontal impact conditions, their biofidelity under vertical loading is less known. The objective of this study was to compare the THOR-K dummy model response to the corresponding response of the THUMS human FE model in the same impact conditions. A series of vertical drop tests were performed on a THOR- K crash dummy. Impact conditions were replicated in the FE simulation based on pre-impact velocities and crash pulse decelerations measured during testing. FE simulations were run with both dummy and human FE models using LS-DYNA ® software. Comparisons between injury prediction of dummy and human models were also performed. While a good correlation was observed in terms of neck load between both FE models, the THUMS spine showed a higher bending flexibility within the sagittal plane. In addition, differences were observed in pelvis region where a significant bouncing was observed in THOR model, but not in the THUMS model. The comparison of THOR FE model with THUMS human model may help to improve the THOR design and define better injury criteria for vertical loading.

• A Numerical Investigation on the Ballistic Performance of Ceramic Composite Armors against EFP Threats

  M. Emin Akca, M. Bartu Ünal, Koray Kaya, H. Hüseyin Türkmen

  The increasing destructiveness of explosive-formed penetrators or projectiles (EFPs) in modern warfare has posed significant challenges in developing effective armored solutions incorporating advanced ceramics as crucial components, offering enhanced protection against high-velocity-formed projectiles. [1] In other words, Explosively Formed Penetrators pose a significant threat to military vehicles, necessitating the development of advanced armor solutions to counteract their destructive potential. Thus, Finite Element Analysis (FEA) research is crucial for the armor system against this threat. In addition, since EFP tests are costly and time-demanding, performing these experiments with FEA provides significant cost and performance efficiency. This study analyzes the composite armor system integrating Nurol Teknoloji [2] ceramics against EFP threats utilizing LS-DYNA, a program for nonlinear dynamic analysis of structures in three dimensions.

• A Numerical Investigation of Turbulent Flow in Circular U-Bend

  A. Miloud, M. Aounallah, O. Imine, M. Guen (University of Science and Technology of Oran Algeria)

  A numerical investigation of Turbulent flows through a circular 180° curved bend with defined as the bend mean radius to pipe diameter for a Reynolds number of 4.45×104 is presented in this study . The computation domain is performed for a U-Bend with full long pipes at the entrance and at the exit. Two turbulence models were tested in this work.

• A Numerical Model for Tri-Axially Braided Composites Under High Velocity Soft Projectile Impact

  Jingyun Cheng, Wieslaw K. Binienda - The University of Akron, Akron OH

  A simplified methodology has been developed for modeling 2D tri-axially braided composite plates impacted by a soft projectile using an explicit nonlinear finite element analysis code LS-DYNA. Fiber preform architecture is modeled using shell elements by incorporating the fiber preform architecture at the level of integration points. The soft projectile was modeled by an Equation of State (EOS). An arbitrary Lagrangian-Eulerian (ALE) formulation is used to resolve numerical problems caused by large projectile deformation. The computed results indicate that this numerical model is able to simulate a tri-axially braided composite undergoing a ballistic impact effectively and accurately, including the deformation and failure with a reasonable level of computational efficiency.

• A numerical study of the effect of geometrical factors on bi-layered tube hydroforming

  Abed Alaswad, Abdul Ghani Olabi - Dublin City University

  Tube hydroforming is one type of unconventional metal forming process in which high fluid pressure and axial feed are used to deform a tube blank in the desired shape. Bi-layered tube hydroforming is suitable to produce bi-layered joints which can be used in special applications such as aerospace, oil production, and nuclear power plants. In this work a finite element study was performed using ANSYS LS-DYNA to investigate the effect of geometrical factors (Tube length, Initial thickness, and Corner radius) on bi-layered tube hydroforming of X branch. Bulge height, Von mises stresses, and thickness distribution were studied for the hydroformed part. Suggestions were made to increase formability of process by adjusting geometrical factors. Optimization was performed to get minimum thickness reduction for a specific design.

• A numerical study of the effect of geometrical factors on bi-layered tube hydroforming

  Abed Alaswad, Abdul Ghani Olabi - Dublin City University

  Tube hydroforming is one type of unconventional metal forming process in which high fluid pressure and axial feed are used to deform a tube blank in the desired shape. Bi-layered tube hydroforming is suitable to produce bi-layered joints which can be used in special applications such as aerospace, oil production, and nuclear power plants. In this work a finite element study was performed using ANSYS LS-DYNA to investigate the effect of geometrical factors (Tube length, Initial thickness, and Corner radius) on bi-layered tube hydroforming of X branch. Bulge height, Von mises stresses, and thickness distribution were studied for the hydroformed part. Suggestions were made to increase formability of process by adjusting geometrical factors. Optimization was performed to get minimum thickness reduction for a specific design.

• A Numerical-Experimental Investigations on Crash Behaviour of Skin Panels during a Water Impact Comparing ALE and SPH Approaches

  Eng. Edoardo Francesconi, Prof. Marco Anghileri - Politecnico di Milano

  Water landings in emergency are likely to have tragic consequences for helicopters. Most of the safety devices developed to enhance helicopter crashworthiness have been designed referring to ground impacts and they might be not effective in case of water landings. At LAST, the crash labs of Politecnico di Milano, water impact drop tests were carried out to deepen the knowledge of the event dynamics and to collect reliable data to validate numerical models. The water impact behaviour of skin panels made of aluminium alloy was investigated, in particular the panel failure due to water impact pressure. Drop tests with several drop heights and different impacting masses were performed measuring accelerations of the test article. In the second part of the research, the tests were numerically reproduced adopting ALE and SPH approaches to model the fluid region. The numerical results were compared both ones to the others and to the experimental tests in terms of impact dynamics and data acquired. As a result, a satisfactory correlation was achieved and guidelines to model fluid regions adopting ALE and SPH approaches were drawn.

• A Numerical-Experimental Investigations on Crash Behaviour of Skin Panels during a Water Impact Comparing ALE and SPH Approaches

  Eng. Edoardo Francesconi, Prof. Marco Anghileri - Politecnico di Milano

  Water landings in emergency are likely to have tragic consequences for helicopters. Most of the safety devices developed to enhance helicopter crashworthiness have been designed referring to ground impacts and they might be not effective in case of water landings. At LAST, the crash labs of Politecnico di Milano, water impact drop tests were carried out to deepen the knowledge of the event dynamics and to collect reliable data to validate numerical models. The water impact behaviour of skin panels made of aluminium alloy was investigated, in particular the panel failure due to water impact pressure. Drop tests with several drop heights and different impacting masses were performed measuring accelerations of the test article. In the second part of the research, the tests were numerically reproduced adopting ALE and SPH approaches to model the fluid region. The numerical results were compared both ones to the others and to the experimental tests in terms of impact dynamics and data acquired. As a result, a satisfactory correlation was achieved and guidelines to model fluid regions adopting ALE and SPH approaches were drawn.

• A PARAMETRIC AND USERFRIENDLY APPROACH TO INCREMENTAL PROCESS SIMULATION OF SHEET METAL FORMING

  Dr. Victor Apanovitch, Stefan Huhn - Forming Technologies Inc.

  With a steady increase in computational power and decrease in hardware costs during the last few years, the incremental process simulation in the area of sheet metal forming is considered a state-of- the-art tool during the development process at OEMs and many, mainly larger, suppliers. However, the existing pre-processing tools do not support a template based analysis setup that can prevent the need for highly skilled personnel in order to set-up an analysis application and, therefore; open the door for an LS-DYNA based stamping simulation for smaller companies that do not have the skill set and manpower available to do the analysis setup using existing tools. The presented solution FormingSuite FastIncremental, is an analysis environment that provides the end user with a dramatically simplified solution for the setup process for incremental stamping analysis using the LS-DYNA solver. This is done through the automation of tool definition/extraction and an automated setup for blank on curved binder combined with other techniques to enable fast solving time. To ensure an optimized solution time, a combination of inverse and incremental finite element tools is used. This combination can lead to enormous time savings in blank development and positioning, tool definition, binder wrap calculation as well as in simulation run-time while reliable results are produced. The user interface is CAD-like and geared towards an average industry practitioner; definition of complete forming processes as well as the application of boundary conditions is mapped on the first form geometry as it is commonly used on A-layouts in the industry. Associative and regenerative mechanisms ensure that changes made to the first form geometry or to forming conditions are automatically propagated throughout the complete analysis process, ensuring that geometry, forming conditions and results are always in sync. This also means that in conjunction with an automated tool generation, the presented tool enables an automated batch mode processing for pre-defined part groups without any user interaction other than evaluating the calculated results.

• A PARAMETRIC AND USERFRIENDLY APPROACH TO INCREMENTAL PROCESS SIMULATION OF SHEET METAL FORMING

  Dr. Victor Apanovitch, Stefan Huhn - Forming Technologies Inc.

  With a steady increase in computational power and decrease in hardware costs during the last few years, the incremental process simulation in the area of sheet metal forming is considered a state-of- the-art tool during the development process at OEMs and many, mainly larger, suppliers. However, the existing pre-processing tools do not support a template based analysis setup that can prevent the need for highly skilled personnel in order to set-up an analysis application and, therefore; open the door for an LS-DYNA based stamping simulation for smaller companies that do not have the skill set and manpower available to do the analysis setup using existing tools. The presented solution FormingSuite FastIncremental, is an analysis environment that provides the end user with a dramatically simplified solution for the setup process for incremental stamping analysis using the LS-DYNA solver. This is done through the automation of tool definition/extraction and an automated setup for blank on curved binder combined with other techniques to enable fast solving time. To ensure an optimized solution time, a combination of inverse and incremental finite element tools is used. This combination can lead to enormous time savings in blank development and positioning, tool definition, binder wrap calculation as well as in simulation run-time while reliable results are produced. The user interface is CAD-like and geared towards an average industry practitioner; definition of complete forming processes as well as the application of boundary conditions is mapped on the first form geometry as it is commonly used on A-layouts in the industry. Associative and regenerative mechanisms ensure that changes made to the first form geometry or to forming conditions are automatically propagated throughout the complete analysis process, ensuring that geometry, forming conditions and results are always in sync. This also means that in conjunction with an automated tool generation, the presented tool enables an automated batch mode processing for pre-defined part groups without any user interaction other than evaluating the calculated results.

• A Path Towards Including Batteries in Electric or Hybrid Car Crash Simulations with LS-DYNA®

  Pierre L’Eplattenier, Iñaki Çaldichoury (Livermore Software Technology, LLC)

  Safety is an important functional requirement in the development of large-format, energy-dense, lithium-ion (Li-ion) batteries used in electrified vehicles. Many automakers have dealt with this issue by enclosing the batteries into protective cases to prevent any penetration and deformation during the car crash. But with the range of electric vehicle increasing and thus the size of the batteries, a more detailed understanding of a battery behavior under abuse becomes necessary. Computer aided engineering (CAE) tools that predict the response of a Li-ion battery pack to various abusive conditions can support analysis during the design phase and reduce the need for physical testing. In particular, simulations of the multi-physics response of external or internal short circuits can lead to optimized system designs for automotive crash scenarios. The physics under such simulations is quite complex, though, coupling structural, thermal, electrical and electrochemical. Moreover, it spans length scales with orders of magnitude differences between critical events such as internal shorts happening at the millimeter level, triggering catastrophic events like the thermal runaway of the full battery. The time scales also are quite different between the car crash happening in milliseconds and the discharge of the battery and temperature surge taking minutes to hours. A so called “distributed Randles circuit” model was introduced in LS-DYNA in order to mimic the complex electrochemistry happening in the electrodes and separator of lithium ion batteries [1][2][3]. This model is based on electrical circuits linking the positive and negative current collectors reproducing the voltage jump, internal resistance and dumping effects occurring in the active materials. These circuits are coupled with the Electromagnetics (EM) resistive solver to solve for the potentials and current flow in the current collectors and the rest of the conductors (connectors, busses, and so forth). The EM is coupled with the thermal solver to which the joule heating is sent as an extra heat source, and from which the EM gets back the temperature to adapt the electrical conductivity of the conductors as well as the parameters of the Randles circuits [1]. One of the advantages of the Randles circuit model is the relative easiness to introduce internal short circuits by just replacing the Randles circuits in the affected area by a short resistance [1][3]. The Randles circuit model also is coupled with the mechanical solver of LS-DYNA where the deformations due to a battery crush allow the definition of criteria to initiate internal shorts [1]. The Randles circuit model can be used either on a solid element mesh that include all the layers of a cell [1][2][3], or using composite Tshells [4][5]. In the second case, the mechanics is solved on the composite Tshell, but an underlying solid mesh with all the layers still has to be built to solve the EM and the thermal. This implies very large meshes and hence simulation times when dealing with many cells, let alone modules, packs or a full battery. This new Battery Macro (BatMac) model allows simulating a cell with very few layers of elements (down to one). Two fields exist at each node of the mesh, representing the potential at the positive and negative current collectors. These two fields are connected by a Randles circuit at each node. It still is possible to include external and internal shorts. The internal shorts can be locally created depending on local values of different mechanical, thermal or EM parameters. The Joule Heating generated by the current leaking through the short resistance is sent to the thermal solver.

• A Performance Study of LS-DYNA on Vehicle Crash Simulation

  Yih-Yih Lin - Hewlett-Packard Company, Cing-Dao Kan - The George Washington University

  For computer companies to design cost-effective machines for LSTC to optimize the software and for the LS-DYNA user to make an intelligent choice of machines, various factors that affect LS-DYNA’s performance must be investigated and understood. Therefore, we have embarked such an investigation with machines from both Hewlett- Packard and SGI. Many results are reported here. The factors considered include the following: memory systems, SMP vs. MPP LS-DYNA, single vs. double precision, cluster vs. ccNUMA configuration.

• A Peridynamic Model for Damage Prediction of Fiber-reinforced Composite Laminate

  Bo Ren, C. T. Wu, Livermore Software Technology Corporation

  This paper presents the keywords for a bond-based peridynamic model in LS-DYNA® to predict the damage of fiber reinforced composite laminates. To represent the anisotropy of a laminate by the peridynamic model, a lamina is simplified as a transversely isotropic media under the plane stress condition. The laminated structure is modeled by stacking the surface mesh layers along the thickness direction according to the laminate sequence. The bond stiffness can be evaluated using the engineering material constants, based on the equivalence between the elastic energy density in the peridynamic theory and the elastic energy density in the classic continuum mechanics theory. Benchmark tests are conducted to verify the proposed model. The numerical results illustrate that the elastic behavior of a laminate can be simulated accurately in comparison to experimental data. In terms of damage analysis, the proposed model can capture the dynamic process of the complex coupling of the inner-layer and delamination damage modes.

• A physically based strength prediction model for glass

  Jonas Rudshaug, Odd Sture Hopperstad, Tore Borvik

  The strength of glass has been a subject of great interest for more than one hundred years. Due to the stochastic nature of glass, originating from microscopical surface flaws, glass plates exhibit large variations in fracture strength. The aim of this work is to present a new strength prediction model for glass, named the Glass Strength Prediction Model (GSPM) that captures the nature of fracture initiation in glass, spanning from rate dependence to size effects. We aim for the presented model to be applicable in modern design processes and provide a procedure to facilitate input parameter calibration for glass plates from different suppliers. GSPM is a Monte-Carlo based model that combines the theories of linear elastic fracture mechanics (LEFM) and sub-critical crack growth (SCG) to generate virtual tests on a representative sample of glass plates. The stress evolution in the glass plates is obtained from finite element (FE) simulations. The model results in representative fracture strength distributions that span the probable fracture initiation instances with respect to time, location and stress level. We demonstrate how the GSPM can be used to trigger fracture in the constitutive model MAT_280 in LS-DYNA. This feature provides the option to investigate scenarios including multiple glass plates with interdependent fracture initiation behavior. The GSPM displays great promise in terms of usability and prediction capacity. It can capture the fracture initiation behavior of glass plates of varying geometries exposed to load cases spanning from, e.g., quasi-static four-point bending to blast pressure. The model has the potential to reduce the number of physical experiments and numerical FE simulations in modern development processes of glass structures.

• A Pre-processor Software for the Calibration of Material Models for LS-DYNA

  H. Lobo (Matereality)

  LS-DYNA contains a wealth of material models that allow for the simulation of transient phenomena. These models are often quite complex and difficult to calibrate. We present CAE Modeler, a generalized pre-processor software used to convert material property data into material parameters for different material models used in CAE. In this paper, CAE Modeler is used to streamline the conversion of rate dependent stress-strain data into material parameters for the MAT_024 material model. The interactive software is capable of handling all three rate dependency options of MAT_024 and outputs a data file that can be read directly into LS-DYNA. Support for other material models is envisaged.

• A pregnant woman model to study injury mechanisms in car crashes

  Jérémie Pérès, Michel Behr, Lionel Thollon - IFSTTAR, Kambiz Kayvantash - CADLM

  Based on statistical analysis it has been estimated that 3 to 7% of pregnant women experience trauma, 2 third of those trauma are caused by car accidents. According to one epidemiologic study, the frequency of foetal losses could exceed the death frequency of children aged 0 to 4. Some numerical and experimental tools have recently been developed so as to better understand injury mechanisms leading to foetal losses, nevertheless shortcomings regarding the anatomy of the models must be outlined. Indeed they lack internal organs whereas there is a direct interaction with the uterine wall. Moreover the simplified amniotic fluid model (lagrangian) often implemented is not validated. To fulfil the need of an anatomically precise pregnant woman model, a first finite element model of a 9 month pregnant woman has been developed and validated via a PMHS experimental approach. This model was based on the Humos 50th centile male model and a simplified model of the amniotic fluid was used (Lagrangian). This paper will present the development and validation of the second generation of this model using the LS Dyna software. The geometry of the Humos 50th centile male model was adapted to the anatomy of a 50th centile woman using scaling techniques with a special focus on the pelvis. The model integrates the uterine wall, the foetus, the placenta and an Euler model for the amniotic fluid and represents the anatomy of a 7 month pregnant woman. The uterus is surrounded with main internal organs and bones. An improved PMHS approach was used for validation purpose. Some belt loading of the abdomen and crash tests were realized and compared to the numerical response of the model in similar loading conditions. The pregnant numerical model exhibited a response in agreement with the PMHS tests and will be used to investigate mechanisms leading to fetal losses. A study on parameters influencing the risk of fetal loss is also projected and could ultimately lead to specific safety systems designs.

• A Process for Robust Design of a Vehicle Front Structure Using Statistical Approach

  Masahiro OKAMURA (JSOL Corporation)

  In recent years, it has become more and more important to take scatter into account in automotive industry. Liability and performance has been guaranteed by adding safety margin to its target in the past. However, needs in cost reduction and trade-off of conflicting requirements do not allow manufacturers enough amount of safety margin any longer[1]. One way to reduce scatter in product performance is to control production quality. However, too much control increases managing cost, and scatter cannot be reduced more than tolerance specified by standards. There are some studies showing major scatters in response are sensitive to boundary conditions such as dummy position and offset or angle of crash barriers[1,2]. However, these are set up by third parties in hardware tests so that the parameters are beyond control[3]. For the reasons above, realistic approach for the problem is to enhance product design which absorbs scatter in production process and boundary conditions. Conventional methods based on design space scan[4] only visualize non-linear transformation of input/output variables, which illustrate relationship of scatters, and physical mechanisms and how scatters propagate is a black box. In this study, scatter propagation mechanism is visualized based on statistical calculation, and structural design is enhanced in order to reduce scatter using the front side structure of an automobile as an example. A process for analyzing scatter propagation mechanisms using statistical analysis software DIFFCRASH is proposed. The trigger of bifurcation is located, selection of deformation mode is made, mechanism of the bifurcation is studied, and design modification is made to stabilize the deformation mode.

• A Process of Decoupling and Developing Body Structure for Safety Performance

  John M. Madakacherry, Martin B. Isaac, Dr. Charles A. Bruggeman - General Motors, Dr. David Eby - CD-Adapco, Dr. Akbar Farahani - ETA, Inc., Dr. Ron C. Averill - Red Cedar Technology

  This paper describes a novel approach of decoupling and developing local structures for crash performance . The process discussed here enables quick development of local structure to address packaging changes in a mass efficient manner. Hundreds of design choices compatible with other design constraints were evaluated to select the optimized design. Here optimum is defined as the design that met the required parameters (crashworthiness, NVH, package, manufacturability and robustness) at the minimum mass. A large number of choices could be evaluated by using a highly simplified simulation process, since the goal was often making an A-to-B choice at a local level, as opposed to predicting exact performance at a system level. The primary focus of mass reduction was efficiency of the load path strategy, and exploitation of the unique geometrical shapes feasible in the hydroforming process. The designs were also rendered robust through a Montecarlo Simulation process for manufacturing variations and small variations in angle of impact. A subset of the new design was incorporated into a vehicle, which was tested full-scale under the ODB format. Cost constraints prevented complete rebuilding of the load path. The optimized test vehicle had comparable performance when compared to the original design, although the mass of load carrying members was reduced by 20%.

• A Process of Decoupling and Developing Optimized Body Structure for Safety Performance

  John M. Madakacherry, Martin B. Isaac, Dr. Charles A. Bruggeman - General Motors, Dr. David Eby - CD-Adapco, Dr. Akbar Farahani - ETA, Inc., Dr. Ron C. Averill - Red Cedar Technology

  A large class vehicle meeting NCAP front crash and 40-mph 40% Offset Deformable Barrier (ODB) Impact performance was modified and tested to verify a new load path strategy using hydroformed structure and new analytical tools to reduce the mass of the vehicle while meeting the same or better performance as in the original design. The new approach was used for developing the load path strategy of a complex system model by decomposing it into structural subsets. Components in the load path were developed primarily through decoupled structural simulations. The method facilitated evaluation of a large number of design choices compatible with other design constraints. The primary focus of mass reduction was efficiency of load path strategy and exploitation of unique geometrical shapes feasible in a motor compartment rail hydroforming process using new optimization techniques (HEEDS). In addition, the components were made insensitive to prescribed variations to insure robust system level performance. A subset of the new optimized design was incorporated into the ODB test vehicle for verifications. The test vehicle (original architecture and new hydroformed motor compartment structure) had comparable performance though the mass of new vehicle load carrying members was 20% less.

• A Quadratic Pipe Element in LS-DYNA®

  Tobias Olsson, Daniel Hilding (DYNAmore Nordic AB)

  Analysis of long piping structures can be challenging due to the enormous number of shell/solid elements that would be required to model a piping structure accurate. In that context a new beam element has been developed that can, if used correctly, reduce the number of elements used in a pipe simulation. Since it is constructed of 3 nodes it is perfect for describing pipe bends, so called elbows. This documentimplemented inDYNA R7 [1]. is meant as an introduction and modelling techniquesLS-DYNA® R7.0.0 but improvements are implementedfor the elbowin the comingelement. It is update of LS-DYNA R7

• A Rate-Dependent, Elasto-Plastic Cohesive Zone Mixed-Mode Model for Crash Analysis of Adhesively Bonded Joints

  Stephan Marzi, Olaf Hesebeck, Markus Brede - Fraunhofer IFAM, Felix Kleiner - Henkel AG & Co. KGaA

  Presently, there are various cohesive zone models implemented in LS-DYNA. The simplest one consists of a bi-linear traction separation-law in both modes I and II. Further models allow more complicated shapes of the traction-separation law, such as the material model of Tvergaard and Hutchinson or the General Cohesive Zone Model. However, none of these implemented models consider rate-dependency or effects of plasticity. Crash-optimized structural adhesives used in automotive structures, as for example Henkel Terokal 5077, often show a rate-dependent elastic-plastic material behaviour. An extended mixed-mode co- hesive zone model is proposed in this paper. The model considers the effects of rate-dependency and plasticity, and therefore is able to predict the failure of adhesively bonded joints more precisely than the common models. The material parameters describing the rate-dependency of yield strengths or critical energy release rates can be identified directly by (fracture) mechanical tests. The new model is validated by simulations of single lap-shear, T-peel, End-Loaded Shear Joint (ELSJ) and Tapered Double Cantilever Beam (TDCB) tests. A comparison of numerical and experimental results shows the benefits and the limitations of the new model, which will be available from one of the next versions of LS-DYNA. Its official name will be MAT COHESIVE MIXED MODE ELASTOPLASTIC RATEDEPENDENT, or in short MAT 240. The tests were proceeded at velocities ranging over several orders of magnitude. The results, which depend strongly on the test velocity, are predicted well by the new model. Further advantages are seen, when simulating a specimen unloading during a TDCB test. The irreversible displacement after unloading, which is caused by the adhesive’s plasticity, is obtained also in simulations when using the new model. Finally, a side-impact test on a floor pan is simulated, using the new model to predict the failure of adhesive bond lines connecting a cross beam to the structure. The crash tests were performed by Adam Opel GmbH. First simulations of such impact tests, using MAT 138 to model the adhesive layer, were already presented at the recent German LS-DYNA-Forum in Bamberg. The new results obtained with the elastic-plastic, rate-dependent MAT 240 show a good agreement with the experimentally observed behaviour. Thus, the model has been successfully employed in the crash simulation of a large, bonded vehicle structure.

• A Rate-Dependent, Elasto-Plastic Cohesive Zone Mixed-Mode Model for Crash Analysis of Adhesively Bonded Joints

  Stephan Marzi, Olaf Hesebeck, Markus Brede - Fraunhofer IFAM, Felix Kleiner - Henkel AG & Co. KGaA

  Presently, there are various cohesive zone models implemented in LS-DYNA. The simplest one consists of a bi-linear traction separation-law in both modes I and II. Further models allow more complicated shapes of the traction-separation law, such as the material model of Tvergaard and Hutchinson or the General Cohesive Zone Model. However, none of these implemented models consider rate-dependency or effects of plasticity. Crash-optimized structural adhesives used in automotive structures, as for example Henkel Terokal 5077, often show a rate-dependent elastic-plastic material behaviour. An extended mixed-mode co- hesive zone model is proposed in this paper. The model considers the effects of rate-dependency and plasticity, and therefore is able to predict the failure of adhesively bonded joints more precisely than the common models. The material parameters describing the rate-dependency of yield strengths or critical energy release rates can be identified directly by (fracture) mechanical tests. The new model is validated by simulations of single lap-shear, T-peel, End-Loaded Shear Joint (ELSJ) and Tapered Double Cantilever Beam (TDCB) tests. A comparison of numerical and experimental results shows the benefits and the limitations of the new model, which will be available from one of the next versions of LS-DYNA. Its official name will be MAT COHESIVE MIXED MODE ELASTOPLASTIC RATEDEPENDENT, or in short MAT 240. The tests were proceeded at velocities ranging over several orders of magnitude. The results, which depend strongly on the test velocity, are predicted well by the new model. Further advantages are seen, when simulating a specimen unloading during a TDCB test. The irreversible displacement after unloading, which is caused by the adhesive’s plasticity, is obtained also in simulations when using the new model. Finally, a side-impact test on a floor pan is simulated, using the new model to predict the failure of adhesive bond lines connecting a cross beam to the structure. The crash tests were performed by Adam Opel GmbH. First simulations of such impact tests, using MAT 138 to model the adhesive layer, were already presented at the recent German LS-DYNA-Forum in Bamberg. The new results obtained with the elastic-plastic, rate-dependent MAT 240 show a good agreement with the experimentally observed behaviour. Thus, the model has been successfully employed in the crash simulation of a large, bonded vehicle structure.

• A Real World Approach for using LS-DYNA to Achieve True Springback Compensation on SS Components During Forming

  M. Clarke - Continental Tool and Die, J. He - Engineering Technology Associates, Inc., X. Zhu - LSTC

  Springback is every tool designer’s nightmare. A tool designer can make a die adjustable for some areas that need to be over-hit. Most parts are sprung throughout their entire surface. In these cases the entire part would need adjustment. Almost every time the die always requires a re-cut/re-work to put the part in spec. This re-work and re-cut is a time consuming, trial and error method that takes shop resources which typically are not available near the end of a build. This presentation illustrated a method which uses DYNAFORM/LSDYNA as the analysis tool, associates with the measurement procedure, provides a complete process and a effective way for the springback compensation needs. This procedure saves hours of measurement and modelling time. In many cases, a single re-cut of the die is all that would be required to achieve the correct compensation in even the most difficult parts.

• A Real World Approach for using LS-DYNA to Achieve True Springback Compensation on SS Components During Forming

  M. Clarke - Continental Tool and Die, J. He - Engineering Technology Associates, Inc., X. Zhu - LSTC

  Springback is every tool designer’s nightmare. A tool designer can make a die adjustable for some areas that need to be over-hit. Most parts are sprung throughout their entire surface. In these cases the entire part would need adjustment. Almost every time the die always requires a re-cut/re-work to put the part in spec. This re-work and re-cut is a time consuming, trial and error method that takes shop resources which typically are not available near the end of a build. This presentation illustrated a method which uses DYNAFORM/LSDYNA as the analysis tool, associates with the measurement procedure, provides a complete process and a effective way for the springback compensation needs. This procedure saves hours of measurement and modelling time. In many cases, a single re-cut of the die is all that would be required to achieve the correct compensation in even the most difficult parts.

• A Review of S-ALE Solver for Blast Simulations

  I. Kurtoglu, B. Balaban (FNSS Savunma Sistemleri)

  Blast modeling and simulation is a very important field in the military land vehicle industry. Increasing demands for higher protection levels leads the engineers to more challenging design and simulation cases. In most situations, Arbitrary Lagrange Euler (ALE) method is the most well-known method for blast simulations and also for determining the effects of blast loads on structures. Various studies are performed for the effect of mesh size and the domain shape for traditional ALE solver of LS-DYNA. The newly implemented S-ALE solver is stated to give shorter simulation times and also less memory requirements using the advantage of structured mesh. In this work, the S-ALE solver is compared to the traditional ALE solver for mine blast in steel pod. Different mesh sizes and advection methods are used for comparison. In addition to the displacement, momentum and deformation pattern, the solution times and memory requirements are also examined. Fluid-structure interaction (FSI) performance for solid interfaces is reviewed, as well.

• A Review of S-ALE Solver for Blast Simulations

  I. Kurtoglu, B. Balaban (FNSS Savunma Sistemleri)

  Blast modeling and simulation is a very important field in the military land vehicle industry. Increasing demands for higher protection levels leads the engineers to more challenging design and simulation cases. In most situations, Arbitrary Lagrange Euler (ALE) method is the most well-known method for blast simulations and also for determining the effects of blast loads on structures. Various studies are performed for the effect of mesh size and the domain shape for traditional ALE solver of LS-DYNA. The newly implemented S-ALE solver is stated to give shorter simulation times and also less memory requirements using the advantage of structured mesh. In this work, the S-ALE solver is compared to the traditional ALE solver for mine blast in steel pod. Different mesh sizes and advection methods are used for comparison. In addition to the displacement, momentum and deformation pattern, the solution times and memory requirements are also examined. Fluid-structure interaction (FSI) performance for solid interfaces is reviewed, as well.

• A Review of Sixteen Years of LS-DYNA® Application in Stamping Manufacturing Engineering at Chrysler, LLC

  Yang Hu, Changqing Du and Shyam Kariat - Chrysler, LLC, Li Zhang - Livermore Software Technology Corporation

• A Review of Strucural Part Modelling for Blast Simulations

  G. Balaban, I Kurtoğlu (FNSS Savunma Sistemleri)

  In this study, the effects of various element formulations and mesh sizes are investigated for buried charge simulations using the non-linear finite element code LS-DYNA®. Simulations are performed according to the real test conditions and the results are compared with the plate level mine blast experiments. Tests are carried out using a test setup which is designed and manufactured by FNSS. The blast simulations are examined using ALE method. Simulation model consists by ALE domain which includes soil, air and the explosive definitions and Lagrange domain for the bottom and side plates of the vehicle. The evaluated test plate is made of RHA steel with 20 mm thickness. Simplified Johnson Cook material model is used and the parameters are determined by Split-Hopkinson Pressure Bar tests. Plates are modelled using shell, solid and thick shell elements with different element formulations. Consequently, the elastic and plastic deformation results, effective plastic strain distributions, pressure histories and the cpu times are compared. Furthermore, the advantage and disadvantages of the considered formulations and parameters are presented.

• A review of the state-of-the-art in vehicle modeling for crashworthiness analysis using LSDYNA

  Paul du Bois

• A Roadmap to Linear and Nonlinear Implicit Analysis with LS-DYNA

  G. Laird (Predictive Engineering)

  The default LS-DYNA settings are tailored for running large explicit analyses. For new and even experienced users, it can be challenging setting up an implicit LS-DYNA analysis to match analytical solutions or other standard implicit FEA codes. For example, the default element formulations are based on single-point integration whereas implicit analyses benefits from full-integration. A series of example problems are provided that will allow the simulation engineer to exactly match industry standard implicit codes (complete keyword decks can be found at DYNAsupport.com). Along with these example decks, CPU-scaling results will be presented for each implicit analysis type from linear to nonlinear.

• A Robust Cohesive Zone Model for Cyclic Loading

  Ala Tabiei, Wenlong Zhang (University of Cincinnati)

  Cohesive element approach is a promising way to simulate crack propagation. Commonly used cohesive laws include bilinear law, trapezoidal law and exponential law. However, research has found that when exponential cohesive law is unloading or reloading, the traction curve cannot remain continuous when the mixed mode ratio changes. (Kregting 2005) [1] In this paper, the discontinuity behavior of exponential law is discussed and a remedy is given to handle that. Instead of using a constant unloading slope, we use an unloading and reloading slope that changes with mixed mode ratio, like the damage parameter used in bilinear model. Improved Xu-Needleman’s exponential cohesive law will be used as an example to show this improvement. Its application in cyclic loading for fatigue failure is presented.

• A SEISMIC POST ELASTIC BEHAVIOR OF SPHERICAL TANKS

  Pascal Pourcel - TECHNIP, Estelle Coussedière, Claire Gauthier, Nima Edjtemai - DYNALIS

  French regulation for seismic verification of structures is separated in two parts : * the "normal risk" for a structure which affects only it's surrounding when it collapses, * the "special risk" for a structure which could be dangerous for persons at long distances The first category includes all buildings. The calculation methods are in general static and the post elastic behavior is taken into account by a reduction factor. This factor allows to divide seismic stresses by a factor, function of the type of structure. For reinforced concrete and steel structures, values of this factor can be found in literature and codes (PS92 in France). The second category concerns the nuclear field and SEVESO's industrial sites (petrochemical industry for example). For the "special risk", the calculation method is a modal spectral analysis, which is an elastic calculation method too. The ability of a structure to have a ductile post elastic behavior is also taking into account by "reduction factors". The spectrum to be considered is regulatory where the seismic level is low (95% of French territory) and must be calculated elsewhere (taking into account site effects). If we consider industrial equipments, only a few values of this reduction factor exist, and they are not specified in codes. The engineer has to define and justify the values he chooses. To find a solution to this problem, the French Ministry of Environment decided in 1997 to make a comparison of French and US approach for this problem. This document gives values for some equipments but concludes anyway that some more calculations are necessary to be sure of these reduction factors. In 1999, The Ministry of Environment decided to undertake specific calculations for some equipments. This paper presents the first calculations performed for this project.

• A semi-analytical model for polymers subjected to high strain rates

  A. Haufe - DYNAmore GmbH, P.A. Du Bois - Consulting Engineer, S. Kolling, M. Feucht - DaimlerChrysler AG

  Reliable prediction of the behaviour of structures made from polymers is a topic under considerable investigation in engineering practice. Especially, if the structure is subjected to dynamic loading, constitutive models considering the mechanical behaviour properly are still not available in commercial finite element codes. First, we give an overview of material laws for thermoplastics and show how the behaviour can be characterized and approximated by using visco-elasticity and metal plasticity, respectively. Experimental work is presented to point out important phenomena like necking, strain rate dependency, unloading behaviour and damage. A constitutive model including the experimental findings is derived. In particular, different yield surfaces in compression and tension and strain rate dependent failure, the latter with damage induced erosion, need to be taken into account. With the present formulation, standard verification tests can be simulated successfully. Also, an elastic damage model is used to approximate the unloading behaviour of thermoplastics adequately.

• A SIMPLE CORRECTION TO THE FIRST ORDER SHEAR DEFORMATION SHELL FINITE ELEMENT FORMULATIONS

  Romil Tanov, Ala Tabiei - University of Cincinnati

  The present work concentrates on the development of correct representation of the transverse shear strains and stresses in Mindlin type displacement based shell finite elements. The formulation utilizes the robust standard first order shear deformation shell finite element for implementation of the proposed representation of the transverse shear stresses and strains. In this manner the need for the shear correction factor is eliminated. In addition, modification to any existing shell finite element for the correct representation of transverse shear quantities is minimal. Some modifications to correct Mindlin type elements are presented in the literature. These modifications correct the distribution of the transverse shear stresses only and use the constant transverse shear strains through the thickness. As compared to the above, the present formulation uses the correct distribution and is consistent for both transverse shear stresses as well as transverse shear strains.

• A Simple Ejection Mitigation Device to Increase Survival of Standing Gunner

  M.S. Hamid (Advanced Computational Systems, LLC)

  It is a challenging task to provide warfighters protection due to impact related injuries such as skull fracture, lower leg and ankle fractures and neck and spinal injuries, which might occur during underbody blast. Tremendous improvements in design of ground vehicles have minimized these injuries. Further improvement can be achieved by new technology solutions by adding a simple passive device to existing design with minimal changes in order to mitigate occupant ejection for a vehicle occupant experiencing underbody blast while standing at nametag, defilade through round hatch opening as part of their operational duty. The patented device is an energy absorbing box with corrugated sheets in all four sides and welded to the top and bottom plates. The top and bottom plates are connected with brackets. The top plate and the brackets are connected with tension failure plates. The corrugated sheets act like energy absorbing (EA) bellows. The EA capacities can be increased by adding collapsible stiffeners inside the box. The device is virtually evaluated in an occupant standing position in a vehicle using LS-DYNA® and LS-PrePost®. The standing occupant is modeled using ATD from LSTC. Modeling of the Gunner Restraint System (GRS) used to keep the occupant in position is developed by using Seatbelt Fitting application module in LS-PrePost. An acceleration pulse is applied to the vehicle in order to represent the effect of blast load. The EA mechanism is evaluated for various side plate thicknesses and heights of the device. The reductions in tibia force and head excursion relative to hatch are presented.

• A Simple Global/Local Approach to Modeling Ballistic Impact onto Woven Fabrics

  M. P. Rao, M. Keefe - University of Delaware, Newark, B. M. Powers, T. A. Bogetti - United States Army Research Laboratory, Aberdeen Proving Ground

  The objective of this study is to develop and demonstrate the feasibility of an LS-DYNA® Global/Local model for studying the non-linear mechanics of woven fabrics under ballistic impact. The presented approach is built on the observed response of fabrics in experimental studies performed at the Army Research Laboratory (ARL). In particular, two-layer test patches of 600 denier Kevlar KM2® fabrics are modeled with the aim of corroborating experimentally determined V50 velocities and physical deformation patterns. However, the present study begins with a brief overview of detailed three-dimensional (3D) finite element models of the woven fabrics under ballistic impact, comprised of regular undulating geometries of the individual yarn. This model is designated as the Full- Local environment and serves as the baseline for the subsequent Global/Local 3D finite element models. Within this Full-Local environment, the projectile velocity is determined as a function of time, and the response of the fabrics under the applied impact load are presented and discussed. Based on this work, the Global/Local modeling framework is developed that represents the fabric finite element meshes as comprised of combinations of homogenized continuum regions (‘Global’ regions) which neglect yarn undulations, and full 3D undulating yarns (‘Local’ regions). Discussions are presented regarding the implications on the predicted ballistic response of the fabrics. Specifically, comparisons are made for the predicted projectile velocity as a function of time, fabric deformations, energy histories, and computing time required to execute the individual simulations. It is shown that the Global/Local modeling approach results in reasonable savings in computing time without appreciably sacrificing the physics of the problem.

• A Simple Material Model for Composite Based on Elements with Realistic Stiffness

  T. Tryland (Sintef Manufacturing)

  The obvious question is how to combine models and data to create a virtual prediction tool? There is a long history with measured data to adjust finite element models representing the geometry and material properties of a tested component. It seems to be a good starting point to represent the initial geometry with correct stiffness and challenge the element formulations to maintain realistic stiffness even when the elements are severely deformed. A proper discretisation is crucial when building a finite element model, and most metallic parts are represented as continuums although we know about the elementary particles. It is likely that this simplification is acceptable as long as the strains are small and the strain hardening is sufficient to compensate for local variation in material properties, but remember that brittle behaviour may be the result when the elastic energy stored in the component is allocated into the first local area that fails.

• A Simple Weak-Field Coupling Benchmark Test of the Electromagnetic-Thermal-Structural Solution Capabilities of LS-DYNA Using Parallel Current Wires

  William Lawson, Anthony Johnson (General Atomics Electromagnetics)

  To begin learning the coupled field capability of LS-DYNA and validate results, a simple simulation of parallel wires carrying current was run. The magnitude of the current in the wires is such that the coupling between the electromagnetic (EM), thermal and structural fields is weak, in the sense that the coupling is taken to be one way. That is, there is no feedback amongst the three field solutions. This allows us to compare LS-DYNA code and known analytical results for code validation to build confidence that the code is being correctly used. LS-DYNA results are also compared to ANSYS results when no analytical results are valid. In addition, this simulation allowed us to test the transfer of EM generated Ohmic heating to the thermal field, and the transfer of EM generated forces to the structural field, a necessary process for coupling fields.   Furthermore, to be able to compare the code and analytical results, temperature-dependent material properties have not been included  a decent approximation with the low currents used.  The set-up of the coupled field model is discussed. Comparison of the LS-DYNA code and analytical results show good agreement where applicable. Comparison with ANSYS results is also good.

• A Simple, Efficient and Robust Way to do Binder Wrap Simulation with LS-DYNA Implicit Solver

  Kaiping Li, Yang Hu - ASME, Chrysler Group LLC, Xinhai Zhu - Livermore Software Technology Corp.

  With the newly improved LS-DYNA implicit solver, the possibility to use it for binder wrap simulations of Stamping Process becomes reality. The importance of binder wrap simulation can never be overly emphasized since it will not only approve or disapprove the concepts of binder shape design, hence the whole addendum development of stamping process, but also impact the final results of stamping process simulations.

• A Simplified Approach for Strain-Rate Dependent Hyperelastic Materials with Damage

  D.J. Benson - University of California, S. Kolling- DaimlerChrysler AG, P.A. Du Bois - Consulting Engineer

  Simulation of rubber-like materials is usually based on hyperelasticity. If strain-rate dependency has to be considered viscous dampers are added to the rheological model. A disadvantage of such a description is time- consuming parameter identification associated with the damping constants. In this paper, a tabulated formulation is presented which allows fast generation of input data based on uniaxial static and dynamic tensile tests at different strain rates. Unloading, i.e. forming of a hysteresis, can also be modeled easily based on a damage formulation. We show the theoretical background and algorithmic setup of our model which has been implemented in the explicit solver LS-DYNA [1]-[3]. Apart from purely numerical examples, the validation of a soft and a hard rubber under loading and subsequent unloading at different strain rates is shown.

• A simplified approach to the simulation of rubber-like materials under dynamic loading

  Paul A. Du Bois - consulting engineer

  The simulation of rubber materials is becoming increasingly important in automotive crashworthiness simulations. Although highly sophisticated material laws are available in LS-DYNA to model rubber parts, the determination of material properties can be non-trivial and time consuming. In many applications, the rubber component is mainly loaded uniaxially at rather high strain rates. In this paper a simplified material model for rubber is presented allowing for a fast generation of input data based on uniaxial static and dynamic test data.

• A Simulation-Driven System Design Methodology with Manufacturing Constraints

  Kaushik Sinha - DaimlerChrysler Research and Technology

  This paper presents a holistic simulation-driven system design methodology considering multiple performance objectives, performance constraints including formability criterion defined herein, using a genetic algorithm based multi-objective optimization software GDOT, developed in-house. This tool treats multiple objective functions separately without combining them in any form. A decision-making criterion is subsequently invoked to select the “best” subset of solutions from the obtained non-dominated Pareto optimal solutions under multiple performance constraints along with a formability index. Geometric properties, associated material properties (yield strength / plastic strain to failure) are considered as design variables. An example involving the frontal impact on a rail section is used to demonstrate the methodology. This process can further suggest requirements for synthesizing new materials that will result in optimal product performance. The objective of this study is to establish an ‘optimized’ set of design parameters with the dual aim of (i) minimizing the structural weight and (ii) maximizing energy absorption efficiency of the front rail system during frontal impact. The performance constraints being maximum transmitted force, maximum intrusion, pulse efficiency and formability criterion. This study also looks at the effect of parameter uncertainty on the optimal design. This study is composed in two stages. The first stage attempts to solve the multi-objective optimization problem, which is attempted using proprietary GDOT optimization code. Stage two performs reliability-based multi-objective optimization to generate a ‘reliable’ pareto optimal front. A 2nd order meta model is developed using responses, including formability index, computed from physics-based finite element models using LS-DYNATM analysis code. Looking at a broader picture, this methodology can potentially fill the gap between numerically optimized system development and simulation-driven digital product development. This, in turn, will help realize numerical simulation-driven product development process by aiming to achieve designs that are “first time right”.

• A Smoothed-Particle Hydrodynamics (SPH) Model for Machining of 1100 Aluminum

  S. S. Akarca, W. J. Altenhof, A.T. Alpas - University of Windsor

  The smoothed-particle hydrodynamics (SPH) technique was used to model experimentally observed large deformation behaviour of aluminum (1100 Al) during machining. The effectiveness of the SPH method in predicting the response of the 1100 Al workpiece during orthogonal machining has been assessed through a careful comparison with the experimentally measured stress/strain distribution within the chips formed during steady state cutting. An Eulerian numerical model, previously validated for machining of copper, was also used to evaluate the SPH model. Both the Eulerian and SPH models showed good overall correlation with the experimentally measured stress/strain distribution when an exponential stress-strain behaviour was utilized in modeling. The maximum predicted plastic strains utilizing an Eulerian and SPH solution approach were 7.5 and 8.0, respectively. When the CPU time requirements were considered, the SPH model was the suitable choice to model deformation processes during cutting with relatively good accuracy and approximately 2.75 times less cost compared to the Eulerian model.

• A Standardized Mechanism to Validate Crash Models for Ductile Plastics

  Megan Lobdell, Brian Croop, Hubert Lobo (DatapointLabs)

  Quantifying simulation accuracy before running crash simulations could be a helpful confidence building measure. This study continues our development of a mechanism to validate material models for plastics used in modeling high-speed impact. Focusing on models for isotropic materials that include options for rate dependency and failure, we explore other models commonly used for ductile plastics including MAT089 and MAT187.

• A Status Review of Failure Simulation at the Federal Aviation Administration

  D. Cordasco, W. Emmerling (Federal Aviation Administration); P. DuBois (George Mason University)

  The Federal Aviation Administration (FAA) is developing models and methods for simulating fan blade off impact for engine containment. Accurately predicting deformation and failure in such an event is essential for advancing the industry and FAA goal of certification by analysis. Furthermore, industry and government engineers require publicly available tools to standardize the analysis during the engine design, development and certification phase. In addition to the high strain rates and steep temperature gradients typically realized in the impact event, a complex three-dimensional state of stress develops which is dependent on the impactor and target material properties, geometry, relative orientation and impact velocity. The resulting failure surfaces which characterize the plastic failure strain by the state of stress fully defined by the triaxiality and Lode parameter are highly nonlinear. Often, crucial stress state data points are not easily realized by typical specimen level standard tests necessitating the development of new experiments to fully characterize the surface for a given material.

• A Strategy to Design Bird-proof Spinners

  Prof. Marco Anghileri, Dr. Luigi-Maria L. Castelletti, Ing. Dario Molinelli, Ing. Federico Motta - Politecnico di Milano

  Birdstrike is a serious threat for flight safety which causes every year remarkable losses. Even if modern aircrafts are certified for a level of bird impact resistance, it may happen that structures designed to carry aerodynamic loads, like a propeller spinner, may collapse after a bird strike. In general, the collapse of the spinner is not a concern if the fly-home capability is not compromised. In this paper, a strategy to design bird-proof spinner is introduced and its effectiveness evaluated by means of LS-Dyna. A SPH model of the bird was initially developed and validated. Then the impact of the bird onto a composite spinners was investigated. In particular, to capture its complex failure mechanism, the dynamic behaviour of the composite material used in the aircraft constructions was validated against specific dynamic tests. The influence of the spinner motion was also investigated and the differences between motionless and revolving spinners were pointed out. Improvements to the design of the reference spinner based on the idea of deflecting-the-bird instead of bagging-the-bird were developed and their performances numerically evaluated. In view of the results obtained, it was concluded that composite material and rotational motion can be exploited to design bird-proof spinner. Furthermore, it was observed that increasing the thickness of a spinner is not only against the weight constraints typical of aircraft constructions, but it is also ineffective.

• A Strategy to Design Bird-proof Spinners

  Prof. Marco Anghileri, Dr. Luigi-Maria L. Castelletti, Ing. Dario Molinelli, Ing. Federico Motta - Politecnico di Milano

  Birdstrike is a serious threat for flight safety which causes every year remarkable losses. Even if modern aircrafts are certified for a level of bird impact resistance, it may happen that structures designed to carry aerodynamic loads, like a propeller spinner, may collapse after a bird strike. In general, the collapse of the spinner is not a concern if the fly-home capability is not compromised. In this paper, a strategy to design bird-proof spinner is introduced and its effectiveness evaluated by means of LS-Dyna. A SPH model of the bird was initially developed and validated. Then the impact of the bird onto a composite spinners was investigated. In particular, to capture its complex failure mechanism, the dynamic behaviour of the composite material used in the aircraft constructions was validated against specific dynamic tests. The influence of the spinner motion was also investigated and the differences between motionless and revolving spinners were pointed out. Improvements to the design of the reference spinner based on the idea of deflecting-the-bird instead of bagging-the-bird were developed and their performances numerically evaluated. In view of the results obtained, it was concluded that composite material and rotational motion can be exploited to design bird-proof spinner. Furthermore, it was observed that increasing the thickness of a spinner is not only against the weight constraints typical of aircraft constructions, but it is also ineffective.

• A Study Concerning Precision of LS-DYNA Res

  Martin Feyereisen, Jeff Zais, Guangye Li - IBM

• A Study in Mass Scaling for Sheet Metal Forming with LS-DYNA®

  Jeanne He Du Bois and Paul Du Bois, Forming Simulation Technology LLC

  Metal Forming simulation requires the deformed sheet metal to catch the tooling shapes precisely. With the limitation of lower order elements, mesh refinement is required to represent the key features of the geometry. In reality, the tooling travel speed is very low. Consequently, the physics of sheet metal forming involves a long termination time induced by the low Tool travel speed and a small timestep induced by the fine mesh. Many techniques are available to reduce the computation time for this important class of simulations. This presentation will study the effect of mass scaling, adaptive meshing and the related factor of tool travel speed and attempt to determine the acceptable range of settings for sheet metal forming simulation analysis. We will also identify what are the key criteria to identify the reliability of the simulation results.

• A Study of LS-DYNA Implicit Performance in MPP

  Dr. C. Cleve Ashcraft, Roger G. Grimes, and Dr. Robert F. Lucas - Livermore Software Technology Corporation

  LS-DYNA models for Implicit Mechanics are getting larger and more complex. We are continually seeing models where the linear algebra problems in Implicit Mechanics have 10M rows and know of at least one that is nearly 40M rows. We expect users wanting to routinely solve problems with 30M very soon. It is these very large linear algebra problems that distinguish the computer requirements for Implicit Mechanics. This paper will present a study of the performance of the MPP implementation of implicit mechanics in LS-DYNA examining such issues as performance, speed-up, and requirements for computer configuration.

• A Study of LS-DYNA Implicit Performance in MPP

  Dr. C. Cleve Ashcraft, Roger G. Grimes, and Dr. Robert F. Lucas - Livermore Software Technology Corporation

  LS-DYNA models for Implicit Mechanics are getting larger and more complex. We are continually seeing models where the linear algebra problems in Implicit Mechanics have 10M rows and know of at least one that is nearly 40M rows. We expect users wanting to routinely solve problems with 30M very soon. It is these very large linear algebra problems that distinguish the computer requirements for Implicit Mechanics. This paper will present a study of the performance of the MPP implementation of implicit mechanics in LS-DYNA examining such issues as performance, speed-up, and requirements for computer configuration.

• A Study of LS-DYNA® Implicit Running the Rolls-Royce® Large Representative Engine Model with Intel® Optane™ DC Persistent Memory Technology

  Nick Meng (Intel Corporation), Roger Grimes, Robert Lucas, Francois-Henry Rouet (Livermore Software Technology (LST), an ANSYS company), James Ong (Rolls-Royce Holdings Corp.)

  In this paper we discuss Intel’s continued efforts to optimize the performance of LS-DYNA Implicit. We focus on the Rolls-Royce® Large Representative Engine Model (LREM), the largest implicit model known to Livermore Software Technology. Performance analysis indicated three opportunities for improvement: shared memory parallelization of the LS-GPart reordering code, optimization of the multifrontal linear solver, and usage of Intel® Optane™ DC Persistent Memory. We present results taken while running the LREM model with a tuned hybrid version of LS-DYNA R12.r144413 HYBRID_DP on 2nd Generation Intel® Xeon™ Platinum 8260L scalable processor (formerly Cascade Lake) cluster with Intel’s Optane persistent Memory. We depict the benefits of Intel Optane persistent Memory technology and discuss the techniques needed to optimize LS-DYNA.

• A Study of Mapping Technique for Air Blast Modeling

  Vincent LAPOUJADE, Nicolas VAN DORSSELAER - Alliance Services Plus, Sandrine KEVORKIAN, Karine CHEVAL - Institut de Radioprotection et de Sûreté Nucléaire

  Since LS-DYNA® v971 r4, a new 2D ALE method with an associated Mapping technique is available. Mapping enables the decomposition of a calculation in several steps: at the end of a 2D ALE calculation, data from the last cycle can be mapped into another 2D or 3D mesh. Several finite element studies of Air Blast were modeled to evaluate efficiency and potential of this new LS-DYNA feature. First, an influence study was performed to evaluate the impact of the mesh characteristic length variation during the Mapping on shock wave both on pressure peaks and impulses. The analysis is focused on the evaluation of the loss due to the Mapping technique. Then, a comparison with experimental data on a simple 2D study of air blast using Mapping technique was performed. The very good precision obtained with the 2D ALE method and its ability to represent air blast phenomena will be shown.

• A Study of Material and Architectural Effects on the Impact Response of 2D and 3D Dry Textile Composites using LS-DYNA

  Gaurav Nilakantan, Michael Keefe, John W. Gillespie Jr. - University of Delaware, Travis A. Bogetti, Rob Adkinson - US Army Research Laboratory

  High strength 2D fabrics and 3D textile composites comprised of materials such as KevlarTM, VectranTM, ZylonTM, and S2-Glass® find applications in protective systems such as personnel armor, spall liners, and turbine fragment containment. Various parameters can significantly affect the response of these fabrics under high rate impact including yarn/tow geometry (cross section), yarn/tow material (modulus, strength), and architecture (undulations and span). However these are just a few of the many other parameters such as projectile characteristics, boundary conditions, number of layers and orientations, weaving degradations, and so forth. Many of these parameters are inter-related and unfortunately this makes a comprehensive study very complex. Therefore, a set of key parameters have been identified for an initial exploratory numerical investigation. These include, on the material front: yarn/tow axial modulus, strength, frictional coefficient; and on the architectural front: yarn/tow cross section shape, size, span, and angle of inclination of through-thickness stitching or Z-tows. This study provides interesting initial insight into the role of through thickness tows on the overall impact resistance and energy dissipation capabilities for which these high strength fabrics were designed for. 3D fabrics with varying Z-tow architectures are compared against each other as well as against 2D fabrics without through thickness stitching. A special in-house preprocessor DYNAFAB is used to automatically generate the entire textile composite mesh. The user inputs basic parameters describing the desired yarn/tow geometry, architecture, and mesh density. The output is a LS-DYNA keyword input-file ready to use in the simulation. The geometry and undulations in the FE model closely represents the actual micrographs of the textile composite leading to a realistic representation of the architecture.

• A Study of Material and Architectural Effects on the Impact Response of 2D and 3D Dry Textile Composites using LS-DYNA

  Gaurav Nilakantan, Michael Keefe, John W. Gillespie Jr. - University of Delaware, Travis A. Bogetti, Rob Adkinson - US Army Research Laboratory

  High strength 2D fabrics and 3D textile composites comprised of materials such as KevlarTM, VectranTM, ZylonTM, and S2-Glass® find applications in protective systems such as personnel armor, spall liners, and turbine fragment containment. Various parameters can significantly affect the response of these fabrics under high rate impact including yarn/tow geometry (cross section), yarn/tow material (modulus, strength), and architecture (undulations and span). However these are just a few of the many other parameters such as projectile characteristics, boundary conditions, number of layers and orientations, weaving degradations, and so forth. Many of these parameters are inter-related and unfortunately this makes a comprehensive study very complex. Therefore, a set of key parameters have been identified for an initial exploratory numerical investigation. These include, on the material front: yarn/tow axial modulus, strength, frictional coefficient; and on the architectural front: yarn/tow cross section shape, size, span, and angle of inclination of through-thickness stitching or Z-tows. This study provides interesting initial insight into the role of through thickness tows on the overall impact resistance and energy dissipation capabilities for which these high strength fabrics were designed for. 3D fabrics with varying Z-tow architectures are compared against each other as well as against 2D fabrics without through thickness stitching. A special in-house preprocessor DYNAFAB is used to automatically generate the entire textile composite mesh. The user inputs basic parameters describing the desired yarn/tow geometry, architecture, and mesh density. The output is a LS-DYNA keyword input-file ready to use in the simulation. The geometry and undulations in the FE model closely represents the actual micrographs of the textile composite leading to a realistic representation of the architecture.

• A Study of MPP LS-DYNA ® Performance on Hardware Configurations

  Yih-Yih Lin and Toshihiro Ishibashi (Hewlett Packard Enterprise)

  With vehicle crash simulation models of sizes up to 10M elements, this paper will investigate how LS-DYNA performance is affected by the four hardware components: processor, I/O, memory, and interconnect network. First, two aspects of processor will be studied: performance gain from Intel Turbo Boost and performance gain from the AVX2 over the SSE2 instruction set architecture. Second, performances of using a local storage, a shared NFS file system, and a shared LUSTRE file system will be measured. Third, three aspects of memory will be studied: DIMM’s frequency, cache coherence snooping modes, and balance-ness of memory configurations. And fourth, performances of two interconnect network switches will be compared: Mellanox IB-FDR and IB-EDR .

• A Study of Pedestrian Kinematics and Injury Outcomes Caused by a Traffic Accident with Respect to Pedestrian Anthropometry, Vehicle Shape, and Pre-Impact Conditions

  Costin D. Untaroiu, Wansoo Pak, Yunzhu Meng, Virginia Tech, Blacksburg, VA, USA;, Berkan Guleyupoglu, Scott Gayzik, Wake Forest University, Winston-Salem, NC, USA

  Pedestrians represent one of the most vulnerable road users. In the U.S., pedestrian fatalities show an increasing trend from 11% of total traffic fatalities in 2007 to about 15% in 2015. The rapid advancement in finite element (FE) technology, material testing, and computational power promotes FE car-to-pedestrian collision (CPC) simulations as a very useful component in the vehicle design process (e.g., in designing deployable devices for pedestrian head protection). The objective of this study was to investigate the sensitivity of pedestrian kinematics and injury outcomes to pedestrian anthropometry, vehicle shape, and pre-impact conditions (e.g. vehicle speed, relative position of pedestrian to the vehicle).

• A Study of Quasi-static Problem by SPH Method

  Tatsuo Sakakibara, Toru Tsuda, Ryo Ohtagaki - ITOCHU Techno-Solutions Corporation

  The SPH method is well known for the hydrodynamics and recently SPH is applied for the impact and the penetration behavior into solid materials. SPH is completely mesh free so that it seems to be appropriate to simulate crash behaviors of concrete and rock materials. However, the applicability and the effects of the parameter of SPH for quasi-static problems are not clear completely. In this paper, in order to verify the applicability and the accuracy of SPH on quasi-static problems, a number of unconfined uni-axial compression simulations are performed by SPH. The specimens of different number of elements are used and the parameter sensitivities of SPH are examined. The influences of formulation type of SPH in LS-DYNA® are also investigated. The results of SPH are compared with the Laglangian result. From the results, the effects of the parameter for SPH are made clear. Besides, it is found that the renormalized formulation is efficient to get the accurate results at boundary. As the result, it is conformed that SPH is applicable for the quasi-static problems.

• A Study of RC Beam-Column Against Close-in Blast Loading Using 3D ALE Mapping to S-ALE Technique

  Zoey Lim Siew Fern, Sun Jian Yun, Heng Zi Jing, Ang Choon Keat

  Mapping technique has been developed to allow the decomposition of a calculation in several steps. The transitions are allowed 1D to 2D/3D, 2D to 2D/3D, or 3D to 3D/2D etc [1], that the data from the model’s latest cycle is saved in a binary file and can be mapped into another model using the “map” command in the expression. This technique has a wide range of application since it allows to adjust mesh length or model size, as well as include Lagrangian or Eulerian Parts.

• A Study on a Multi-Disciplinary Optimization Method for the PMP

  Soon-Young Seo, Jae-Woo Jeong, Dong-Hyeob Cho, Hyuk Kim - Samsung Electronics Co. Ltd.

  In the mobile electronic appliances market, the feature of products is getting smaller, thinner and more multi- functional. Therefore, mobile products are easily damaged from drop/impact and thermal cycling load. To make them more reliable under these conditions, the junction area between chips and PCB should be designed to bear up under drop/impact. And the heat caused by main chip (Memory & DMB channel chip) should be dissipated as quickly as possible. From the viewpoint of CAE simulation, although those two problems (drop & heat) should be considered simultaneously, they should not. Because the outline of PCB mainly depends on the location of main chip, positioning the main chip is one of the most important steps in the initial design stage. And the dynamic stress from free drop and heat caused by main chip are the one of the most critical factors to position the main chip. This paper presents the design process for positioning the main chip on PCB of PMP using MDO method. That is, the trade-off design variables between drop and thermal loading analysis were identified and system level optimization is performed in parallel. The main theme of this paper is to provide a way to get MDO solution of the PMP model in the early design stage.

• A study on blast-loaded aluminium plates with crack-like defects subjected to blast loading

  H. Granum (Enodo), D. Morin, T. Børvik, O. Sture Hopperstad (NTNU)

  This paper presents a study on AA6016 plates in temper T4 subjected to blast loading. Four different crack-like defects have been introduced in the plates to facilitate crack propagation as the dominating failure mode. Uniaxial tensile specimens extracted from a plate are used in the calibration of the *MAT_258 material model available in LS-DYNA. This material model contains a non-quadratic yield surface, isotropic work hardening and a failure model where the onset of failure is dependent on the element size as well as its bending-to-membrane loading ratio. Four different element sizes are investigated to assess the ability of the model to predict the onset of failure and subsequent crack propagation in blast-loaded plates by comparison to experiments conducted in a shock tube facility.

• A Study on Delamination Behavior between Aluminum and CFRTP

  Masahiro Okamura, JSOL Corporation;, Shin Horiuchi, The National Institute of Advanced Industrial Science and Technology

  In the near future, it is predicted that automobiles will use extensive amount of light weight material such as aluminum and CFRP. However, joining these material needs structural adhesive on the purpose of isolation and avoiding local stress concentration. In this paper, a simulation model has been built up using LS-DYNA® for DCB (double cantilever beam) test. Combination of various thicknesses in aluminum and CFRTP specimen has been studied to assess structural toughness. Validity of the simulation model has been confirmed by comparing the results with experiments, and trends and detailed mechanisms are discussed.

• A Study on Preparation of Failure Parameters for Ductile Polymers

  Kunio Takekoshi, Kazukuni Niwa (TERRABYTE Co., Ltd)

  A study on preparation method of failure parameters for ductile polymers is presented using experimental results of high-speed tensile test for Polycarbonate and simulation results based on Semi-Analytical Model for Polymers (SAMP) constitutive model [1] in LS-DYNA®. In addition, a comparative review of two widely used failure models, namely, total formulation and incremental formulation [2, 3], is carried out using Charpy impact test simulations where the failure parameters are prepared using the proposed method. It is found that the incremental formulation is excellent in predicting the experimentally observed behavior of notched Charpy impact test and non-notched Charpy impact test.

• A Study on Scatter during Production Process using Statistical Approach using LS-OPT®

  Masahiro OKAMURA, JSOL Corporation

  In recent years, robustness of car body structure has become more important than ever, as car manufacturers are required to achieve conflicting performance in high level such as light weight and crash performance. Major source of scatter in body structures are material scatter and production scatter. Since it is difficult to reduce scatter in material as certain range of scatter is allowed by industrial standard, tightening the quality control is not realistic. Only viable solution is to improve production process such as stamping and joining to address the issue. A common way to assess robustness of the structure is to build response surfaces and study sensitivity of input scatter to output, and there are many papers available on the issues.

• A Study on Shock Wave Propagation Process in the Smooth Blasting Technique

  Masahiko Otsuka, Yamato Matsui, Shigeru Itoh - Kumamoto University, Kenji Murata, Yukio Kato - NOF Corporation. Aichi Branch, Taketoyo

  Explosives can easily generate high energy and ultra-high pressure. In recent years, research on the advanced technological use of explosives is studied in various places. Here we focus on the Smooth Blasting Technique that is applied for tunnel blasting. This technique is performed to fracture concrete and to reduce the quantity of fragments, while avoiding stress concentration of ground pressure during tunnel blasting. When this technique is used, it is important to know what influence it will have. In our calculation code, the analysis of compressible substances, which cells transform greatly like air, was very difficult. In this study, we use LS-DYNA, an analysis code using a finite-element method. By analyzing the stress state of the air hole circumference, multilayer models such as air, Vinyl Chloride and water are analyzed and it aims to get the propagation process of the shock wave. The Arbitrary Lagrangian Eulerian (ALE) method is based on the arbitrary movement of a reference domain, which additionally to the common material domain and spatial domain, is introduced as a third domain. Three equations of state (EOS) are used in this study. The JWL equation of state is applied for the reaction of the explosive, and has form of a perfect gas equation of state. When the density becomes large, exponential terms modify the perfect gas equation of state. The Mie-Gruneisen equation of state is applied for water and poly vinyl chloride, and the linear polynomial equation of state is applied for air.

• A study on the bolt modeling with pre-load for field application

  Han Deok Hee, Kim Dong Hyeon, Kim Young Joon

  When fastening a structure with a bolt, an axial force is generated by the tightening torque of them. This axial force acts as a friction force by the friction coefficient of the fastening part, and becomes a factor that directly affects the deformation of the fastening part. For this reason, there have been many studies on how to make the bolt models for applying preload and users are using various methods. What is common is the construction and evaluation of bolt models with preload requires a lot of working by user. So this study was conducted because it was necessary to easy and exact method for with preload bolt models.

• A Study on the Scalability of Hybrid LS-DYNA on Multicore Architectures

  Yih-Yih Lin - Hewlett-Packard Company

  In this paper, the effects of differences in problem size, number of cores per processor, and interconnect on the Hybrid LS-DYNA’s performance are studied. The result shows that combination of these three factors determines when Hybrid LS-DYNA has a performance advantage over the MPP LS-DYNA.

• A Study on the Transfer of GISSMO Material Card Parameters from 2D- to 3D-Discretization

  Daniel Sommer, Peter Middendorf (University of Stuttgart), Florian Schauwecker (University of Stuttgart / Daimler AG)

  This study presents basic strategies for transfer of LS-DYNA® material card parameters from 2D- to 3D-discretizaion without extensive recalibration. The responses of a material card, calibrated on two-dimensional shell elements, are shown on single-element tests with different element formulations, on multi-element patches and on coupons. From this, magnitudes of error are ascertained and quick recalibration measures on material model parameters are derived. An evaluation of the stress-state of typical GISSMO-type specimen in different thicknesses and discretization-lengths is given and typical stress-states within the Lode-triaxiality stress-space of these specimens are highlighted. Therefrom, a measure of deviation from the calibrated state can be derived and used as a measure for allowable deviation from the 2D stress-state. Furthermore, the information on the three-dimensional stress-states, even in thin specimen, can be used for quick recalibration of parameters on the failure surface.

• A Study on Yielding Function of Aluminum Honeycomb

  Shigeki Kojima - TOYOTA COMMUNICATION SYSTEMS CO., LTD. , Japan, Tsuyoshi Yasuki, Satoshi Mikutsu - Toyota Motor Corporation, Japan, Toshikazu Takatsudo - THE YOKOHAMA RUBBER CO., LTD. , Japan

  This paper describes newly developed yielding function of aluminum honeycomb. Physical compression tests of aluminum honeycomb were performed and it was found that yielding stress of aluminum honeycomb highly depended up on direction of compression. Using these test data, a yielding function was newly derived as a function of volumetric change and angle of compression. The yielding function was introduced to MAT126 as an option. ODB frontal collision analysis result with the yielding function showed much better correlation with test results than with MAT126 without the option.

• A Summary of the Space Shuttle Columbia Tragedy and the Use of LS-DYNA in the Accident Investigation and Return to Flight Efforts

  Matthew Melis, Kelly Carney - NASA Glenn Research Center, Jonathan Gabrys - Boeing, Edwin L. Fasanella - US Army Research Laboratory/VTD, Karen H. Lyle - NASA Langley Research Center

  On February 1, 2003, the Space Shuttle Columbia broke apart during reentry resulting in loss of 7 crewmembers and craft. For the next several months an extensive investigation of the accident ensued involving a nationwide team of experts from NASA, industry, and academia, spanning dozens of technical disciplines. The Columbia Accident Investigation Board (CAIB), a group of experts assembled to conduct an investigation independent of NASA concluded in August, 2003 that the cause of the loss of Columbia and its crew was a breach in the left wing leading edge Reinforced Carbon-Carbon (RCC) thermal protection system initiated by the impact of thermal insulating foam that had separated from the orbiters external fuel tank 81 seconds into the missions launch. During reentry, this breach allowed superheated air to penetrate behind the leading edge and erode the aluminum structure of the left wing which ultimately led to the breakup of the orbiter. In order to gain a better understanding of the foam impact on the orbiters RCC wing leading edge, a multi-center team of NASA and Boeing impact experts was formed to characterize the foam and RCC materials for impact analysis using LS-DYNA. LS-DYNA predictions were validated with sub-component and full scale tests. LS- DYNA proved to be a valuable asset in supporting both the Columbia Accident Investigation and NASA’s return to flight efforts. This paper summarizes the Columbia Accident and the nearly seven month long investigation that followed. The use of LS-DYNA in this effort is highlighted. Contributions to the investigation and return to flight efforts of the multi-center team consisting of members from NASA Glenn, NASA Langley, and Boeing Philadelphia are covered in detail in papers to follow in these proceedings.

• A Survey of Eigen Solution Methods in LS-DYNA®

  Roger Grimes, Liping Li, Eugene Vecharynski, Livermore Software Technology Corporation

  LSTC has been adding several new methods for solving a variety of eigenvalue problems in LS-DYNA. This talk will give a survey of two new methods including MCMS (our implementation of the AMLS algorithm), and an iterative based method based on the Locally Optimal Block Pre-Conditioned Conjugate Gradients Method (LOBPCG). These methods will be contrasted with our standard method of Block Shift and Invert Lanczos. We will also describe our implementation of Sectoral Symmetry, a method to vastly reduce the problem size for models with a high degree of rotational symmetry such as fan blades.

• A Systematic Approach to Model Metals, Compact Polymers and Structural Foams in Crash Simulations with a Modular User Material

  G. Oberhofer, H. Gese - MATFEM Partnerschaft Dr. Gese & Oberhofer, A. Bach, M. Franzen, H. Lanzerath - Ford Research & Advanced Engineering Europe

  Today the automotive industry is faced with the demand to build light fuel-efficient vehicles while optimizing its crashworthiness and stiffness. A wide variety of new metallic and polymeric materials have been introduced to account for these increased requirements. Numerical analysis can significantly support this process if the analysis is really predictive. Within the numerical model a correct characterization of the material behaviour – including elasto-viscoplastic behaviour and failure - is substantial. The particular behaviour of each material group must be covered by the material model. The user material model MF GenYld+CrachFEM allows for a modular combination of phenomenological models (yield locus, strain hardening, damage evolution, criteria for fracture initiation) to give an adequate representation of technical materials. This material model can be linked to LS-DYNA when using the explicit-dynamic time integration scheme. This paper gives an overview on the material characterization of ultra high strength steels (with focus on failure prediction), non-reinforced polymers (with focus on anisotropic hardening of polymers), and structural foams (with focus on compressibility and stress dependent damage evolution) with respect to crash simulation. It will be shown that a comprehensive material model - including damage and failure behaviour - enables a predictive simulation without iterative calibration of material parameters. A testing programme has been done for each material group in order to allow a fitting of the parameters of the material model first. In a second step different component tests have been carried out, which were part of a systematic procedure to validate the appropriate predictions of the crash behaviour with LS-Dyna and user material MF_GenYld+CrachFEM for each material group.

• A Systematic Approach to Model Metals, Compact Polymers and Structural Foams in Crash Simulations with a Modular User Material

  G. Oberhofer, H. Gese - MATFEM Partnerschaft Dr. Gese & Oberhofer, A. Bach, M. Franzen, H. Lanzerath - Ford Research & Advanced Engineering Europe

  Today the automotive industry is faced with the demand to build light fuel-efficient vehicles while optimizing its crashworthiness and stiffness. A wide variety of new metallic and polymeric materials have been introduced to account for these increased requirements. Numerical analysis can significantly support this process if the analysis is really predictive. Within the numerical model a correct characterization of the material behaviour – including elasto-viscoplastic behaviour and failure - is substantial. The particular behaviour of each material group must be covered by the material model. The user material model MF GenYld+CrachFEM allows for a modular combination of phenomenological models (yield locus, strain hardening, damage evolution, criteria for fracture initiation) to give an adequate representation of technical materials. This material model can be linked to LS-DYNA when using the explicit-dynamic time integration scheme. This paper gives an overview on the material characterization of ultra high strength steels (with focus on failure prediction), non-reinforced polymers (with focus on anisotropic hardening of polymers), and structural foams (with focus on compressibility and stress dependent damage evolution) with respect to crash simulation. It will be shown that a comprehensive material model - including damage and failure behaviour - enables a predictive simulation without iterative calibration of material parameters. A testing programme has been done for each material group in order to allow a fitting of the parameters of the material model first. In a second step different component tests have been carried out, which were part of a systematic procedure to validate the appropriate predictions of the crash behaviour with LS-Dyna and user material MF_GenYld+CrachFEM for each material group.

• A Systematic Approach Towards Integrated Safety Modelling for Aerospace Applications – Preliminary Results on Rigid Seat Simulations

  Nina Wegener, Christoph Sauer, Paul Schatrow, Matthias Waimer

  In the aviation sector, the historically evolved crashworthiness requirements prescribe seat certification separately from the airframe structure. Based on historical test and accident data the airframe crash behaviour is presumed in terms of crash pulses, which are applied to the seat structure for seat certification (e.g. EASA CS-23/25.562). Certification authorities have recently started to change the regulations from a prescriptive to a performance-based certification, considering the crash performance with the seats integrated in the airframe structure (EASA CS-23 Amendment 5). With this, occupant safety and structural crashworthiness is combined to an integrated safety approach. Due to the high cost of full-scale testing in the aviation sector, extensive use of simulation is of interest. Modelling methods are continuously being developed for crash loading conditions relevant to aerospace, which significantly differ from automotive ones. The German Aerospace Center (DLR) Institute of Structures and Design has extensive experience in developing simulation methods for aircraft crash analysis. In an effort to develop an integrated safety modelling approach for aviation, a research initiative was launched to incorporate advanced passenger safety considerations.

• A systematic study on Ansys Forming® performance

  Dr.-Ing Kang Shen

  Mesh adaptivity refines the blank mesh as needed in stamping simulations. Users do not need to anticipate where a dense mesh will be required. Despite its universal use, it demands significant effort due to serialization and the need to carry a dense mesh through subsequent iterations. In-Core adaptivity and Mesh fusion assist the solver in conserving effort, thereby enhancing performance. This paper will demonstrate best practices for utilizing In-Core adaptivity and Mesh fusion in Ansys Forming through practical cases. In addition, for different model, we should find an optimum number of CPUs to run the job. Beyond this number, the scalability will not see any obvious improvements.

• A Systematic Study on Topology Optimization of Crash Loaded Structures using LS-TaSC

  K. Weider, A. Marschner, A. Schumacher (Bergische Universität Wuppertal)

  In this contribution the chances and limitations of using LS-TaSC for topology optimization of crash loaded structures will be shown. With two demonstrative examples the influence of scaled loads, intermediate densities and conflicting constraints are discussed. As no analytical sensitivities are available in explicit finite element simulations, LS-TaSC uses the interal energy density as sensitivity, which makes it an efficient optimization strategy for stiffness applications. For the provided examples, both a maximum stiffness as well as a crashworthiness design is developed. In the latter case, the multipoint method of LS-TaSC is used to cope with the acceleration of an impactor as objective function. To compare the resulting topology with other topology optimization methods, a thickness optimization of a shell interpretation is performed. The structural behavior is also compared with that of the optimized solid model.

• A Temperature and Strain Rate Dependent Material Model with Tension-Compression Asymmetry for 0.25 inch Ti-6Al-4V Plate

  Leyu Wang, Paul DuBois, Kelly Carney, Cing-Dao Kan, Center of Collision Safety and Analysis, George Mason University, USA

  Tension-compression asymmetry observed in a 0.25" thick Titanium plate is modeled with *MAT_224_GYS, an isotropic elastic-thermo-viscous-plastic material model in LS-DYNA®. The input deck fits a series of tensile and compression tests at different strain rates and temperatures, conducted on samples cut from a 0.25" commercial off-the-shelf titanium plate. The rate and temperature dependent hardening law is separately defined for the tension and compression response. It is seen that *MAT_224_GYS is capable of capturing the tension-compression asymmetry of Titanium Ti-6Al-4V.

• A three-dimensional finite element model for the roll bending of heavy plates using a 4-roll plate bending machine

  L. Kappis, P. Froitzheim, Prof. W. Flügge (Fraunhofer IGP)

  Roll bending is a manufacturing process in which sheet metal is continuously formed into a round shape with the help of typically three or four rotating rolls. It is used in particular for the production of thick-walled pipes and shells with large volumes, which are used in the maritime sector, in pipeline construction and in the field of renewable energies. In these areas, at the current state of the art, the process is mainly controlled manually. However, the control of the process is of great importance for its efficiency. For example, over-controlling the machine leads to over-bending of the plate and thus often to material waste, whereas under-bending requires additional rolling passes and leads to an increase in production time. To reduce the human influence on the economic efficiency of the process and to objectify the process, research is currently being carried out on the development of automation solutions for roll bending.

• A Toolbox for Validation of Nonlinear Finite Element Models

  Dr. Mark C. Anderson, Timothy K. Hasselman - ACTA Inc., John E. Crawford - Karagozian & Case Structural Engineers

  With increasingly powerful computational resources at our disposal, it is becoming common- place to use analytical predictions in lieu of experimentation for characterization of physical systems and events. This trend, with its perceived potential for reducing costs, is the basis for the simulation-based procurement initiatives currently gaining momentum within the Gov- ernment and industry. However, a simulation-based approach is often sold to decision-makers via plausible visualizations of model simulation results; the simulations themselves having only been validated in an ad hoc manner using anecdotal comparisons with real events. Ex- perience has shown that, while simulation using physics-based models may lead to qualita- tively correct results, there can be large quantitative discrepancies between simulation and experimental results for a given physical event, and between simulation results from different analysts for the same event. Obviously, for simulation-based procurement to be a viable alter- native to more traditional test-based procurement, the quantitative accuracy of the simulations must be insured. To do this requires at least a modicum of experimental data (perhaps at the component or subsystem level) to serve as a yardstick with which the accuracy of simulation results can be measured. And it requires minimizing the differences between corresponding analytical and experimental results in physically meaningful ways, as well as characterizing the ability of the models to predict future events. This paper describes a toolbox for the vali- dation of nonlinear finite element models. The toolbox includes tools for quantitatively up- dating model parameters based on the differences between test results and analytical predic- tions, as well as estimating the predictive accuracy of the model based on generically similar comparisons. Use of the toolbox is illustrated for a DYNA model of a reinforced concrete wall subjected to blast loading.

• A Topology Optimization Tool for LS-DYNA Users: LS-OPT/Topology

  Tushar Goel, Willem Roux, Nielen Stander - Livermore Software Technology Corporation

  Topology optimization is a very powerful tool to develop new concepts and has been widely used in engineering problems involving static loading conditions. However, there has been relatively little work for topology optimization of industrial size non-linear dynamic systems. The main issues are non-linear interactions among the material properties, contacts between parts, large strain-rates, transient behavior, etc. A hybrid cellular automata based method, combining cellular automata theory with the fully loaded design concept, has been demonstrated to be effective in generating new concept designs. This method is called hybrid cellular automata (HCA) and is used as the core algorithm to optimize the topology. This method is implemented in the LS-DYNA framework and would be available shortly. The method has shown encouraging results while solving many engineering problems. In this paper, the details of the methodology and a few engineering examples are provided to demonstrate some capabilities of the code. The main problem solved using the proposed methodology is the development of an optimal topology for a 1 million element box-shaped design domain subject to impact.

• A Topology Optimization Tool for LS-DYNA Users: LS-OPT/Topology

  Tushar Goel, Willem Roux, Nielen Stander - Livermore Software Technology Corporation

  Topology optimization is a very powerful tool to develop new concepts and has been widely used in engineering problems involving static loading conditions. However, there has been relatively little work for topology optimization of industrial size non-linear dynamic systems. The main issues are non-linear interactions among the material properties, contacts between parts, large strain-rates, transient behavior, etc. A hybrid cellular automata based method, combining cellular automata theory with the fully loaded design concept, has been demonstrated to be effective in generating new concept designs. This method is called hybrid cellular automata (HCA) and is used as the core algorithm to optimize the topology. This method is implemented in the LS-DYNA framework and would be available shortly. The method has shown encouraging results while solving many engineering problems. In this paper, the details of the methodology and a few engineering examples are provided to demonstrate some capabilities of the code. The main problem solved using the proposed methodology is the development of an optimal topology for a 1 million element box-shaped design domain subject to impact.

• A Tutorial on How to Use Implicit LS-DYNA

  R. Grimes (LSTC)

  This talk will focus on the issues of using the Implicit features of LS-DYNA. Implicit has a profoundly different footprint regarding the computational resources required than an explicit simulation. This talk will especially focus on the management of those computational resources, especially for distributed memory computations. This talk will also include an overview of techniques for debugging models for use by Implicit.

• A Unified Environment for Collaborative CAE and Immersive Simulation Results Processing

  Stavros Kleidarias, BETA CAE Systems S.A.

  Ever since the first CAE simulations there has always been a need to examine digital models as close to reality as possible. Technology limitations meant that this was done on digital models with unrealistic graphics representation and on a PC monitor. Also, the evaluation of simulation results by engineering teams on different design centers was proven to be inefficient and time consuming, being based on exchanging tediously prepared images, videos and reports.

• A Unified Environment For Processing Test Videos And Simulation Models

  S. Kleidarias, V. Pavlidis (BETA CAE Systems)

  Throughout the development process of a complex structure such as a vehicle, simulation and testing are both present in almost all phases. Being able to use them efficiently and concurrently whenever this is needed, it maximizes the benefit to the user, as this provides valuable information to identify defects in either the simulation or the test and therefore, avoid errors and delays in the development chain. One common type of test result is the videos, very common in crash domain. Enabling the processing of a video, which is a demanding task on its own, within the same environment where the simulation models are being processed, allows for the direct and easy comparison/correlation of the two and the deduction of useful conclusions. This presentation showcases an LS-Dyna model and relevant real test videos both being processed in META, the post-processor of BETA CAE Systems. META forms a single unified environment for detailed model post-processing as well as for complete video processing. First of all the model view can be easily matched to that of the video either in one plane or in perspective view. Synchronisation of video frames and states of the model can be achieved in a simple way. Valuable information can be extracted from the video. Points as well as distances and angles can be tracked on the video and respective results can be readily plotted on the video as well as in a 2D plot. Tracking functionality for user defined points can also overcome cases where the tracked point is hidden for a number of frames and it also allows for manual tracking for certain frames so as to by-pass tracking discontinuity wherever automatic fix is not possible. Measurements on the video are facilitated by overlaying a grid as well as by defining user defined coordinate systems, either static ones or dynamic. The capability for eliminating rigid body motion from video frames, based on anchoring one or two tracked points on the video, can further assist the correlation of the video with a crash simulation model and thus lead to better conclusions.

• A Unified SPH-DEM-FEM Approach for Modeling of Debris Flow Impacts on Protective Structures

  Chun Liu, Zhixiang Yu (Southwest Jiaotong University), Qiang Wang (Shanghai Fangkun Software Technology Ltd)

  Debris flows are rapid gravity-driven unsteady flows of highly concentrated mixtures of water and solid particle material, destroying numerous mountain building structures and traffic facilities. Investigation of debris flows is thus of significance to hazard prevention and mitigation. This paper aims to provide a numerical model capable of reproducing the debris flow impact estimation by accounting for complicated fluid-particle-structure interaction (FPSI) with a unified Smoothed Particles Hydrodynamics (SPH), Discrete Element Method (DEM) and Finite Element Method (FEM) approach. The fluid phase is represented by SPH. The solid phase consists of physical particle(s) is represented by DEM, and deformable solid structure is represented by FEM. The Wenjia gully debris flow is carried out to demonstrate the capability of the coupled model for simulating FPSI as the application of the debris flow impact simulations. Compared the actual situation, the propagation of the debris flow and destruction of structures were predicted. Then, the effectiveness of the treatment measures of the Wenjia gully debris flow was clarified from the impact evolution, impact force. The developed method will contribute to a better understanding of FPSI and is a promising tool for hazard analysis and mitigation.

• A User-Defined Element Interface in LS-DYNA v971

  Thomas Borrvall - Engineering Research Nordic AB

  The user-defined features in LS-DYNA are powerful tools that allow users in academia or industry to verify research results in the context of general and complicated finite element applications. Implementation work concerns only the special field of interest, and there is no need for the comprehensive task of developing and maintaining the complete finite element software. One of the new user-defined features in LS-DYNA v971 is the possibility to define structural solid and shell elements. Up to a total of ten element formulations can be implemented in a single LS-DYNA executable both for explicit and implicit analyses. A high abstraction-level interface is in particular provided for numerically integrated elements, and stabilization schemes can easily be incorporated. There is also the option to implement discrete elements, and property parameters and history variables can be associated with the element. The interface is equipped with additional features that facilitates research on element technology, but also makes it perfectly suited for educational purposes. An overview of the procedure of implementing an element in the new interface as well as invoking it from the keyword input file will be presented.

• A user-defined Folgar-Tucker-based fiber orientation material model for compression molding of fiber/polymer-compounds

  Dominic Schommer, Miro Duhovic, David May, Joachim Hausmann, Heiko Andrä, Konrad Steiner

  LS-DYNA® provides an ever-increasing portfolio of material models covering a wide range of material behavior for solving multi-physics problems. The software also provides users the opportunity to implement their own user-defined material models via FORTRAN code, to describe the behavior of very specific materials. In this work, a user-defined material model has been developed to describe the compression molding behavior of sheet molding compounds (SMCs). A SMC is a composite material based on a thermoset resin reinforced by chopped long fibers. During the compression molding of SMCs, very complex material behavior involving elastic compaction and plastic flow (depending on material composition) occurs, which is dependent on the local fiber orientation, temperature and strain rate. One way to describe the processing behavior of SMC materials as simply as possible is using a building block approach. Following the identification of the most relevant material effects, individual building blocks are created containing the respective mathematical solutions (e.g. compaction and plastic flow behavior).

• A Validation Case Study: Steel Billet Drop Tests and Simulations as Reported in NUREG/CR-6608

  Leonard E. Schwer - Schwer Engineering & Consulting Services, James M. Kennedy - KBS2, Inc.

  Before performing safety assessments of spent fuel storage casks in drop and tipover accident simulations, method validation calculations are required. The validation process is outlined by the Nuclear Regulatory Commission (NRC) [Tang, et al., undated], and specifically requires the satisfactory replication of the steel billet drop tests, reported in NUREG/CR-6608 (UCRL-ID-129211) [Witte, et al., 1998]. In addition to reporting the test results in NUREG/CR-6608, Witte, et al. also provide simulations of the tests using the Lawrence Livermore National Laboratory explicit finite element code DYNA3D [Whirley, 1993]; several other organizations have used the Livermore Software and Technology Corporation code LS-DYNA [Hallquist, 1999]. Although other explicit finite element codes would also be applicable, the material model parameters provided for the concrete pad, upon which the billets are dropped, in NUREG/CR-6608 are specific for the Concrete/Geological Material, i.e. Material Type 16, in DYNA3D and LS-DYNA. This sole fact provides a great incentive for analysts to use DYNA3D or LS-DYNA. This manuscript briefly reviews the test configurations and results with recommendations on which configurations and results should be emphasized in comparisons with simulations. Next a brief review of the simulations presented in NUREG/CR-6608 with comments on the modeling and results and suggested improvements is provided. Then comments are provided on the utility of these results, both experimental and numerical, as a validation of the methodology with a particular emphasis on how they extrapolate to the cases of interest for spent fuel storage casks. Finally, a series of recommendations are included that should be considered, and discussed, by analysts providing simulations for spent fuel storage casks and the authorities requiring the safety assessment of these casks.

• A Variable Finite Element Model of the Overall Human Masticatory System for Evaluation of Stress Distributions During Biting and Bruxism

  S. Martinez, J. Lenz, Prof. K. Schweizer­hof (Karlsruhe Institute of Technology), H. Schindler (University of Heidelberg)

  Simulating the masticatory system during chewing, clenching and bruxism, requires the model to capture the dynamical behavior of its different components: the mandibula and maxilla, the temporomandibular joint (TMJ) including the articular disc and the surrounding cartilage layers, the teeth, the periodontal ligaments (PDL), and the muscles

• A VCCT-Cohesive Approach for the Efficient Modelling of Delamination in Composite Materials

  P. Daniel (Btechc), J. Främby (DYNAmore Nordic), M. Fagerström (Chalmers University), P. Maimí (University of Girona)

  The accurate modelling of delaminations is necessary to capture the correct behavior of composite structures subjected to demanding loads. While the use of cohesive elements is valid when the discretization is smaller than the failure process zone [1], for many composite materials it implies using a fine mesh, typically smaller than 1.0 mm, leading to excessive computational cost for large structures. On the contrary, the Virtual Crack Closure Technique (VCCT) allows the prediction of delamination growth in larger elements [2] but lacks of an energy dissipation mechanism. Therefore, it leads to excessive vibrations when the delamination propagates in dynamic analyses. The present work aims to combine the best of both methods in order to develop a viable solution for large structures, allowing for coarser meshes than what is possible to use today. To do so, the VCCT is used as a failure criterion to predict damage initiation while a cohesive-like model is added to dissipate the released energy. The model has been implemented in LS-DYNA in the frame of an adaptive user element recently published [3,4]. The model has been validated with Double Cantilever Beam, End-Notched Flexure and Mixed-Mode Bending tests. It demonstrates the ability of the method to accurately model delamination with larger elements and higher stable time step.

• A View on the Technology of both Vehicle Content and the Product Creation Process for Supercars

  Neil Hannemann - McLaren Automotive

  All road cars have benefited from constantly improving technology; many of these improvements are not always obvious to the consumer. In the category of Supercars the improvements can be measured in ways that are exciting to an automotive enthusiast. The improvements most visibly noted are items that are part of the content of the car, such as electronic fuel injection, airbags, and items cars have always had, such as tires. These technological improvements can fall into 2 categories; Steady improvements and Breakthroughs. Examples in both categories will be discussed. Less obvious are the improvements in automotive design and development processes. The advent of computer technology, powerful and plentiful enough to make CAD and CAE integral parts of the design and development process, is the most important contributor to this ability. The simulation and analysis that is now possible has contributed to the ability to improve many attributes of a car through optimization, and has also allowed the timescales of the design and development process to be compressed. While not as visible as changing the content of the car, improving the design and development process has had just as profound an affect on opening up the performance envelope of Supercars.

• A Virtual Golf Robot for Golf Equipment Simulation

  Tom Mase - Michigan State University

  The equations of motion for a two-lever pendulum are developed using Lagrange's equation. An assumed kinematic golf swing is used to generate generalized forces to drive the golf robot. These moments are used to generate a golf robot swing using LS-DYNA. The LS-DYNA model is flexible enough so that the model can be used as a virtual laboratory.

• A Viscoelastic-Viscoplastic Time-Temperature Equivalence for Thermoplastics

  V. Dorléans, E. Michau (Faurecia Interior System), R. Delille, F. Lauro, D. Notta-Cuvier, B. Bourel, G. Haugou, H. Morvan (University Polytechnique Hauts de France)

  For automotive suppliers, it is essential to model the behavior of thermoplastics under crash loading and for a large range of temperature typically from -30° until 85°c. Thermoplastics are very sensitive to both strain rate and temperature with an inverse relation: hardening with strain rate and softening with temperature. Generally, a large experimental campaign has to be carried out to identify different behavior laws of the material, each of them for a specific range of strain rate and temperature. Then, according to the characteristics of the loading case, e.g. impact, corresponding behavior laws are chosen in the database to run the numerical simulations. This results in an important experimental cost and a large database to manage. It is then interesting to explore the time-temperature equivalence of thermoplastics to act on both aspects. Relations between strain rate and temperature sensitivities are identified through dynamic mechanical analysis (DMA) in the viscoelastic domain and described through the Williams, Landel and Ferry model or the Arrhenius model for example. For that, a shift factor is experimentally determined and introduced to modify the time step in the behavior model for the finite element simulation, thus simulating an adapted strain rate. As a novelty, the time-temperature equivalence is here extended to the viscoplastic domain by keeping the same shift factor. It therefore becomes possible to cover all the scope of temperature and strain rate of automotive applications from only DMA and tensile tests at room temperature and different strain rates. This approach is implemented in association with viscoelastic, viscoplastic with non-associative plasticity constitutive laws and non-local damage model [1][2][3] and applied to the case of a polypropylene. The time temperature equivalence is validated for the viscoelastic as well as for the viscoplastic parts of the behavior with good experimental/numerical correlation. As a result, the number of material cards required in Ls Dyna is reduced to only one to cover all the simulations. This approach is also under investigation to be applied to the failure model.

• A Weight Balanced Multi-Objective Topology Optimization for Automotive Development

  N. Aulig, S. Menzel (Honda Research Institute Europe), E. Nutwell (Ohio State Uiversity), D. Detwiler (Honda R&D)

• A Zero Thickness Cohesive Element Approach for Dynamic Crack Propagation using LS-DYNA®

  Ala Tabiei, Wenlong Zhang, Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA

  The zero thickness cohesive element approach for arbitrary crack propagation has a deficiency of introducing artificial compliance to the model, especially when cohesive elements are inserted into every element interfaces. For dynamic problems, the artificial compliance decreases the stress wave speed and makes the result less accurate. In this paper, the reason of the artificial compliance is examined, and the bilinear and exponential cohesive law are compared. The work shows that by choosing the right cohesive stiffness, element size and using bilinear cohesive law rather than exponential cohesive law, the artificial compliance issue can be limited to a negligible level without greatly increasing the computational time.

• About Isogeometric Analysis and the new NURBS-based Finite Elements in LS-DYNA

  Stefan Hartmann , David Lorenz - DYNAmore GmbH, David J. Benson - University of California

  In the context of isogeometric analysis many research activities have focused on the use of Non- Uniform Rational B-Splines (NURBS). These NURBS-based finite elements have been studied in depth and it has been shown, that they are particularly well suited for computational analysis leading to qualitatively more accurate results in comparison with standard finite elements based on Lagrange polynomials. Due to these motivating results, NURBS-based finite elements are currently implemented into LS-DYNA. This work outlines the basic ideas of isogeometric analysis and gives a short introduction into NURBS basis functions. The new keyword *ELEMENT_NURBS_PATCH_2D available in LS-DYNA is presented together with various possible options, like shell theories with and without rotational degrees of freedom. Preliminary results on the performance of these new elements are studied by means of a sheet metal forming example discussed in the Numisheet conference 2005.

• Absorbing Materials - Tests Versus Simulations

  R. Ridky, M. Popovic (SVS FEM); M. Drdlova (Výzkumný ústav stavebních hmot); O. Koutny (Bogges)

  An absorption capacity of soft, viscoelastic materials at high strain rates is included in wide range of practical applications. One of the critical questions in any similar analysis is setup of material properties including all physical constants. There are many kinds of tests analysing dynamic properties of absorbing elements. In many cases testing and also numerical simulations are influenced by many types of measurement and simulation conditions. This investigation was focused on relations between particular testing results in their complexity and related numerical simulations as well. The goal of this investigation is to find a numerical material model of absorbing material suitable for explicit numerical simulation especially focused on blast load. Number of variations in real testing is usually strictly limited because of experiment costs. On the contrary numerical simulations have no limits in number of analysed variants but they have handicap in correlation with reality. This should be solved by combined development of requested products. This analysis used four kinds of real tests with different strain rates as consistent and verified points that numerical models should confirm and fill in unknown gaps between them.

• Abuse Characterization and Simulation of Battery Cells Using Layered Approach

  David Poulard, Prakhar Amrute, Pierre L’Eplattenier, Kevin Kong, Vidyu Challa, Inaki Caldichoury

  The adoption of electric vehicles (EVs) has brought renewed attention to battery safety, particularly in scenarios where batteries are subjected to mechanical abuse, such as car crashes. The potential for battery cells to catch fire or exhibit thermal runaway under such conditions necessitates a comprehensive understanding of the underlying physics. The complex interplay of structural, thermal, electrical, and electrochemical phenomena presents a formidable challenge for accurate simulation and prediction of battery behavior. In this context, the integration of multiphysics coupling within Ansys LS-DYNA® has emerged as a crucial tool for studying battery abuse and enhancing safety measures.

• Accelerate Ped-Pro assessments using SimAI

  Srikanth Adya, Akshay Jawale, Pierre Yser

  Deep learning methods have had a significant impact on design process in the recent past. SimAI is a deep learning-based AI platform that has shown to be very effective in approximating the behavior of fluid flow applications, especially fully developed steady state flows simulated by CFD solvers. The underlying neural networks in SimAI are very versatile and can be easily extended to structural applications as well. This study aims at demonstrating the applicability of SimAI for non-linear transient structural simulations like pedestrian protection. We start with a simple Tube Crush model to demonstrate the use of SimAI to predict the deformed shape of the Tube at any time instance. We then train a model on different Tube shapes to show SimAI’s ability to learn from non-parametric geometry. Finaly, we demonstrate how SimAI can be used to accelerate Ped-pro evaluations. The NCAC Accord model is used to generate 96 training points. This dataset is used to train a SimAI model and the resulting trained model can predict the full field hood deformation as well as the HIC value for the corresponding hit location within 10% relative error on any point on the vehicle hood. SimAI is many orders of magnitude faster in predicting the HIC than direct numerical simulation and hence can be very effective in evaluating designs upfront in the vehicle development process.

• Accelerating elastoplastic material models with spare nonlinear regression: A hybrid approach

  G. Bokil, D. Koch, André Haufe, Holger Steeb

  Evaluating material models in Finite Element (FE) simulations is computationally expensive. Recently, Machine Learning (ML) techniques have been explored for accelerating elastoplastic algorithms. One such method includes replacing a part of the algorithm with an ML model which is called the “hybrid” approach. One of the most commonly used algorithms for ductile materials is the J2-based von Mises hardening elastoplasticity. To improve the performance of this model, an ML-based hybrid algorithm was sought. In this algorithm, the expensive iterative plastic correction step was replaced with a single-step prediction from a SINDY-inspired sparse nonlinear regression model.

• Accelerating Implicit LS-DYNA® with GPU

  Yih-Yih Lin (Hewlett-Packard Company)

  A major hindrance to the widespread use of Implicit LS-DYNA is its high compute cost. This paper will show modern GPU, cooperating with CPU, can help remove this hindrance. Performance improvement for Implicit LS-DYNA with GPU relative to that without, as well as from recent GPU and X86 processor, will be studied. The study will cover GPU related hardware issues, including GPU Boost, memory and PCI Express Interface.

• Accelerating Regulatory Test Simulation with LS- DYNA through Process Guidance Technology

  Petter Sahlin, Velayudham Ganesan - ESI Group

  With the strength in implementing best practices process guidance technology has proven dramatically reduced lead times in pre and post processing while meeting the increasing complexity imposed by ever changing safety regulations. Using predefined template processes for regulatory tests, for example for Euro NCAP, ACEA, or FMVSS standards, process guidance technology allows users to be driven or guided by ready made test templates for the most common load cases with LS-DYNA and other crash and safety solvers. When integrated in the pre and post environment modelling and results preparation for load cases such as ECE-21, FMVSS 208, the bumper test, or pedestrian safety, analysis loops are reduced from days and hours down to minutes. This presentation describes why and how process guidance technology is introduced, covering both the technological and organisational aspects and decision made as part of the implementations. With the example of pedestrian safety processes the benefits and issues of implementations are presented.

• Accidental Fuel Drop on Spent Fuel Pool Storage Racks

  Ragunath SANKARANARAYANAN

  Spent Fuel (SF) storage racks are fully submerged in water and stand freely at the bottom of the Spent Fuel Pool (SFP). The water column acts as a coolant for residual heat removal from nuclear fuel and provides radiation shielding. Due to the storage of large quantities of nuclear material, Appendix D to NUREG-0800 Section 3.8.4 [1] specifies that the functionality of the SF racks be demonstrated for the D + L + Fd load combination, where Fd is the force caused by the accidental drop of the heaviest load from maximum height. D and L are the dead and live loads acting on the SF racks.

• Accuracy Issues in the Simulation of Quasi-Static Experiments for the Purpose of Mesh Regularization

  Anthony Smith (Honda R & D Americas Inc. ), Paul Du Bois (LS-DYNA® Consultant)

  Generating an LS-DYNA® material model from coupon-level quasi-static experimental data, developing appropriate failure characteristics, and scaling these characteristics to mesh sizes appropriate for a variety of simulation models requires a regularization procedure. During an investigation of an anisotropic material model for extruded aluminum, numerical accuracy issues led to unrealistic mesh regularization curves and non-physical simulation behavior. Sensitivity problems due to constitutive material behavior, small mesh sizes, single precision simulations, and simulated test velocity all contributed to these accuracy issues. Detailed analysis into the sources of inaccuracy led to the conclusion that in certain cases, double precision simulations are necessary for accurate material characterization and mesh regularization.

• Accurate and Detailed LS-DYNA FE Models of the US- and EUROSID: A Review of the German FAT Project

  Ulrich Franz, Oliver Graf - CAD-FEM GmbH, Grafing/ Munich, Germany

  Finite element side impact dummy models of the USSID and EUROSID are of major interest for industry, as more detailed models are required for better prediction capabilities, but still efficiency has to be maintained to some degree. Both type of models, the so-called FAT- USSID and FAT-EUROSID have been developed by CAD-FEM in cooperation with the German Association for Automotive Research (FAT). The main objective was to achieve highly validated finite element models. During the development process the models are vali- dated at three levels: material, component and assembly and tested finally by sled test appli- cations. Additional input was provided by other type of simulations from the LS-DYNA users within the FAT. This paper summarizes the experience gained during the validation and optimization process which may be used as a guideline for an efficient methodology to generate reliable finite element dummy models. Finally, the good performance of the current USSID and EUROSID models is presented for some selected tests.

• Accurate and efficient dummy models for occupant safety design
• Accurate Prediction of Projectile Residual Velocity for Impact on Single and Multi-Layered Steel and Aluminum Plates

  M. Raguraman and A. Deb - Indian Institute of Science, Bangalore

  The present paper deals with the simulation of impact of jacketed projectiles on thin to moderately thick single and multi-layered metal armor plates using explicit finite element analysis as implemented in LS-DYNA. The evaluation of finite element modeling includes a comprehensive mesh convergence study not previously reported in literature, using both shell and solid elements for representing single-layered mild steel target plates. It is shown that the proper choice of contact algorithm, mesh density, and strain rate-dependent material properties is crucial as these parameters significantly affect the computed residual velocity. The modeling requirements are initially arrived at by correlating against test residual velocities for single-layered mild steel plates of different depths at impact velocities in the range of ~800-870 m/s. The efficacy of correlation is adjudged in terms of a ‘correlation index’, defined in the paper, for which values close to unity are desirable. The experience gained for single-layered plates is next used in simulating projectile impacts on multi-layered mild steel target plates and once again a high degree of correlation with experimental residual velocities is observed. The study is repeated for single- and multi-layered aluminum target plates with a similar level of success in test residual velocity prediction. To the authors’ best knowledge, the present comprehensive study shows in particular for the first time that, with a proper modeling approach, LS-DYNA can be used with a great degree of confidence in designing perforation-resistant multi-layered steel and aluminum armor plates.

• Acoustic Aalysis for Impact Sound with LS-DYNA

  R. Ishii (JSOL); T. Yamamoto (Nihon Emsco); Z. Cui, Y. Huang (LSTC)

  LS-DYNA is heavily used to analysis transient phenomenon like car crash and makes a huge achievement about physical simulation in a wide variety of industry. For the goal of LS-DYNA, gone-model , one-codeh as solution it give you, a wide variety of function has been developed at each section. Nowadays, LS-DYNA has been developed further and become possible to evaluate Frequency domain analysis and Acoustic analysis as FRF/SSD/AcousticBEM/FEM etc. It will be important to consider how it works as actual experiment or how to define and use in order to make it possible to evaluate multi-physics extensively. This study is intend for the evaluation to impact sound when a crash occurs between one object and another. To compare the result with experiment and check the both sound by ear would be fulfilled in this paper. The conventional other softwares executing acoustic analysis executes with frequency domain or also do a transient analysis with the assumption that steady state continues in appropriate period. It defines the source of sound on the surface of object vibrating and put it as input to BEM/FEM. As it is well known LS-DYNA can do a transient analysis, it can calculate the source of sound itself. The object vibrates due to collision and the sound propagates to the air. This is the mechanism for sound. LS-DYNA further is able to calculate acoustic analysis taking over previous collision simulation. The comparison between LS-DYNA analysis and experiment is theme of this paper. In the future, In order that LS-DYNA has evaluated physically many kinds of simulation in one-model and it will be alternative to actual experiment. The consideration at this time is first step to confirm the validity and helpfulness of this solution.

• Acoustic and Vibroacoustic Modeling in LSDYNA Based on Variational BEM

  Ahlem Alia - LML, USTL, Mhamed Souli - LSTC

  The paper concerns the vibroacoustic simulation based on the acoustic Variational Indirect Boundary Element Method (VIBEM) recently implemented in LSDYNA. In this formulation, which assumes a weak acoustic-structure interaction, the transient structural response is computed first. By applying the FFT, it is transformed into a frequency response. The obtained results are taken as boundary conditions for the acoustic BEM. Consequently, the radiated noise at any point into space can be calculated. The efficiency of the present method is checked for both pure acoustic and vibroacoustic problems. The obtained results are in agreement with the analytical solutions.

• Acoustic Radiated Power and Radiation Efficiency Calculation with LS-DYNA®

  Yun Huang, Zhe Cui (Livermore Software Technology, an ANSYS Company)

  The keyword *FREQUENCY_DOMAIN_SSD in LS-DYNA not only provides convenient solution for steady state vibration analysis for structures, but also raises the possibility for acoustic simulation. For example, it can be combined with acoustic boundary element method (keyword *FREQUENCY_DOMAIN_ACOUSTIC_BEM) or acoustic finite element method (keyword *FREQUENCY_DOMAIN_ACOUSTIC_FEM), to compute the acoustic pressure and sound pressure level for vibro-acoustic problems. In addition, with the option ERP for this keyword, one can perform ERP (Equivalent Radiated Power) analysis to get a quick solution for radiated noise, based on the plane wave assumption for the acoustic waves. A new parameter RADEFF has been added to the keyword *FREQUENCY_DOMAIN_SSD_ERP to run acoustic radiated power computation for baffled plates, and also computes the radiation efficiency. With some examples, this paper explains the difference between the ERP (equivalent radiated power) and ARP (acoustic radiated power) and shows how to use this new parameter to compute the acoustic radiated power and radiation efficiency for vibrating structures.

• ACP Process Integrated 3B Forming Optimization

  A. Farahani, D. Mittal (Engineering Technology Associates), J. Shaw (US Steel)

  The automotive and steel industries have several initiatives such as the development of 3 rd Generation Advanced High Strength Steels (AHSS), the Nonlinear Strain Path Project and the A/SP AHSS Stamping Team Projects. These initiatives are efforts to expand the forming design space with AHSS to enable increased part complexity, which will allow AHSS to be incorporated into more vehicle components and enable mass reduction. The proposed approach discussed in this presentation will provide a new tool in the effort to expand the forming design space of AHSS.

• ACP-OpDesign: Optimal Design Gateway: Reveal the Path to Optimized Products

  A. Kaloudis, BETA CAE Systems International AG

  ACP OpDesign is an intuitive and process-guided optimization desktop environment. With its optimization oriented and highly specialized user interface, based on the process depicted as a diagram in the tool, it offers the user the capability to take advantage of an efficient, direct interaction to: - ANSA’s powerful morphing and parametrization functionality - custom-designed META Post-processor tools - Topology and parametric optimization Software (LS-TaSC™ and LS-OPT®) - FEA solvers (LS-DYNA®)

• ACP_Forming_Brochure.pdf
• ACP_Natures_Way.pdf
• ACP_Process_Brochure.pdf
• Adaptation of a solid self-piercing rivet made of aluminum using numerical simulation to extend the application limits

  M. Schlicht, T. Nehls, P. Froitzheim, Prof. W. Flügge (Fraunhofer IGP)

  Increasing resource efficiency, for example through the consistent application and further development of lightweight construction concepts, plays an important role in the development of the mobility sector. This requires a steadily increasing use of high-strength aluminum alloys in primary vehicle structures. A suitable and efficient process for joining high-strength aluminum alloys is solid self-piercing riveting (SSPR). A major advantage of this process is the elimination of time-consuming preparatory work such as pre-drilling, deburring and positioning of the components to be joined, as the rivet punches through these during the installation process. Due to the high stresses on the rivet during the installation process and the lack of knowledge on the use of ultra-high-strength aluminum alloys as the rivet material, solid self-piercing rivets (SSP-rivets) made of steel are generally used. However, against the background of recyclability, thermal expansion and corrosion protection, the use of aluminum SSP-rivets would be desirable.

• Adaptive FEM-DEM simulation of a soft missile impact on a reinforced concrete slab

  Yury Novozhilov, Eric Piskula

  Modeling the behavior of reinforced concrete (RC) structures under the action of destructive loads, considering the non-linear material properties and the strain-rate effects, are prescribed according to the requirements of The International Atomic Energy Agency (IAEA) in the design of buildings and structures of Nuclear Power Plants (NPP) [1]. A soft impact of a body imitating an aircraft engine missile is considered according to experiments [2]. Such a study can determine the ability of RC structures to withstand the impact of an engine or other large aircraft fragment. The paper describes an approach to solving such a problem, especially for a large-thickness under-reinforced slab made of low-quality concrete. Such a combination of design parameters may prove challenging for FE modeling due to significant mesh distortions and the need to model material erosion.

• ADAPTIVE FINITE ELEMENT SIMULATION OF SHEET METAL FORMING PROCESSES USING GRADIENT BASED INDICATORS

  Ramin Moshfegh, Xiangdong Li, Larsgunnar Nilsson, Ramin Moshfegh -Linköping Institute of Technology

  Two mesh refinement indicators based on the gradients of effective stresses (GSIG) and effective plastic strains (GEPS), respectively, are proposed for adaptive finite element analysis of the large deformation, quasi-static or dynamic response of shell structures. The mesh refinement indicators are based on equi-distributing the variation of stresses or plastic strains over the elements of the mesh. A program module is developed and implemented in the nonlinear explicit finite element code LS-DYNA. This module provides element-wise refinement evaluations so that selective mesh refinements are carried out in regions of the mesh where the values of local indicators exceed a user-specified tolerance. The FE model of a conventional deep drawing process is used as numerical model, including both material and geometrical nonlinearities, in order to demonstrate the versatility of the two refinement indicators. Four different refinement indicators, based on angle change, thickness change, GSIG and GEPS based are applied in this investigation. To verify the numerical results against experiments, the anisotropic low carbon steel, FEP04, is used as a reference material. The numerical results are compared with experimental results regarding the thickness distribution versus cup height, effective plastic strain in the deformed sheet and punch force. It is shown that the new proposed indicators can identify finite elements, which have high gradients of stresses or strains so that the mesh is refined in the regions undergoing the most severe deformations and the numerical results are improved.

• Adaptive Mesh Segmentation for Modelling Dynamic Delamination Initiation and Propagation in Thick Composite Laminates

  J. Selvaraj, L. Kawashita, G. Allegri, S. Hallett (University of Bristol)

  Composites subjected to out-of-plane stresses due to impact loading can suffer from multiple delaminations, but modelling these in large scale structures is a challenging problem. To address this, a methodology is proposed for modelling dynamic delamination initiation and propagation in composites. It adaptively segments the mesh with additional nodes which model the discontinuities in the displacement field caused by delamination. Besides, it also introduces cohesive segments between the newly created nodes so that delamination propagation is controlled by an energy criterion. These adaptations are performed ‘on-the-fly’ in a dynamic explicit Finite Element solution without the need for user intervention, and the mesh segmentation technique does not reduce the time increment size for solution stability. A technique to initialise cohesive tractions with minimal disturbances to the surrounding stress field is also presented. This methodology is described here in detail and demonstrated in the commercial finite element software LS-Dyna. Finally, it is validated against experimental data from the existing literature.

• Adaptive Sampling using LS-OPT

  A. Basudhar (LSTC)

  LS-OPT is a design optimization and probabilistic analysis package with an interface to LS-DYNA® that provides a flexible framework to solve several types of design problems. In order to solve the problem, it runs simulations at multiple samples that are selected all at once (single iteration) or iteratively [1]. The iterative approach has two main advantages: require prior knowledge about the sufficient number of samples and instead provides a convergence history it can use updated information from the previous runs to select the samples smartly and thus typically reduces the number of required simulations

• Adaptive Simulated Annealing for Global Optimization in LS-OPT

  Tushar Goel, Nielen Stander - Livermore Software Technology Corporation

  The efficient search of global optimal solutions is an important contemporary subject. Different optimization methods tackle the search in different ways. The gradient based methods are among the fastest optimization methods but the final optimal solution depends on the starting point. The global search using these methods is carried out by providing many starting points. Other optimization methods like evolutionary algorithms that mimic the natural processes like evolution, and simulated annealing that emulates the metal cooling process via annealing can find the global optima but are criticized due to high computational expense. The adaptive simulated annealing algorithm has been proposed to be an efficient global optimizer. This algorithm is implemented in LS-OPT. A few analytical examples and meta-model based engineering optimization examples are used to demonstrate the efficiency of the global optimization using ASA. The optimization results are also compared with the existing LFOPC and genetic algorithm optimization methods.

• Adaptive Simulated Annealing for Global Optimization in LS-OPT

  Tushar Goel, Nielen Stander - Livermore Software Technology Corporation

  The efficient search of global optimal solutions is an important contemporary subject. Different optimization methods tackle the search in different ways. The gradient based methods are among the fastest optimization methods but the final optimal solution depends on the starting point. The global search using these methods is carried out by providing many starting points. Other optimization methods like evolutionary algorithms that mimic the natural processes like evolution, and simulated annealing that emulates the metal cooling process via annealing can find the global optima but are criticized due to high computational expense. The adaptive simulated annealing algorithm has been proposed to be an efficient global optimizer. This algorithm is implemented in LS-OPT. A few analytical examples and meta-model based engineering optimization examples are used to demonstrate the efficiency of the global optimization using ASA. The optimization results are also compared with the existing LFOPC and genetic algorithm optimization methods.

• Adaptive Smoothed Particle Hydrodynamics Neighbor Search Algorithm for Large Plastic Deformation Computational Solid Mechanics

  Kirk Fraser (University of Quebec at Chicoutimi)

  Smoothed Particle Hydrodynamics (SPH) has quickly become one of the most popular mesh-free methods since its introduction in 1977. In the recent years, a great amount of research has been focused on addressing some of the common computational time associated with the SPH method. One of the remaining hurdles is the long computational associated with building the neighbor list. Because of the nature of the original SPH codes (astropyshics), the neighbor search is commonly performed for every element in the domain at each time step. In this work, we develop an optimized neighbor search algorithm that is suitable for deployment on NVidia graphics cards (GPU). The SPH code is written using CUDA Fortran. The algorithm can be used for large plastic deformation computational solid mechanics (CSM) problems. The search uses an adaptive algorithm that updates the neighbor list for individual SPH elements depending whether a plastic strain increment threshold is surpassed. The neighbor list as well as the inter-particle spacing (rij) is re-used for elements that do not surpass the search update criteria. Although in this work we use a Cell based search, the algorithm can be easily adapted for the Direct Search, the Verlet List or a Tree Sort approach. Monaghan’s artificial stress term is added to the momentum equation to suppress the common tensile instability. The XSPH approach is used to update the positions of the SPH elements. The algorithm is shown to reduce the overall computation time by up to 70% without loss of accuracy for CSM simulations when compared with the non-adaptive search method.

• Adaptive Smoothed Particle Hydrodynamics and Higher Order Kernel Function in LS-DYNA®

  Jingxiao Xu, Wei Hu, Bo Ren, Youcai Wu, Xiaofei Pan, C. T. Wu (LST)

  This paper presents the implementation of an adaptive smoothed particle hydrodynamics (ASPH) method for high strain Lagrangian hydrodynamics with material strength in LS-DYNA. In standard SPH, the smoothing length for each particle represents the spatial resolution scale in the vicinity of that particle and is typically allowed to vary in space and time so as to reflect the local value of the mean interparticle spacing. However, in the presence of strongly anisotropic volume changes which occur naturally in most of the applications the local mean interparticle spacing varies not only in time and space, but in direction as well. In ASPH, the isotropic kernel in the standard SPH is replaced with an anisotropic kernel whose axes evolve automatically to follow the mean particle spacing as it varies in time, space, and direction around each particle. By deforming and rotating these ellipsoidal kernels so as to follow the anisotropy of volume changes local to each particle, ASPH can capture dimension-dependent features such as anisotropic deformations with a more generalized elliptical or ellipsoidal influence domain. Some numerical examples are investigated using both SPH and ASPH, also higher order kernel function is studied for both SPH and ASPH formulation. The comparative studies show that ASPH has better accuracy than the standard SPH when being used for high strain hydrodynamic problems with inherent anisotropic deformations, also higher order kernel function has better accuracy than the standard cubic kernel function.

• Adaptive Thermal Boundary Conditions for Smoothed Particle Hydrodynamics

  Kirk Fraser (University of Quebec at Chicoutimi, Predictive Engineering), Laszlo I. Kiss, Lyne St-George (Predictive Engineering)

  Smoothed Particle Hydrodynamics (SPH) is a robust meshfree approach for the simulation of large plastic deformation processes such as high speed cutting, forging, extrusion, and friction welding. Often, heat transfer is an important consideration for such industrial processes; for this reason, the effects of heat loss from convection, radiation, or flux from the free surface should be included. However, because of the meshfree nature of SPH, the elements located at the free surface can change, and are not typically known at each time step. This difficulty makes application of thermal boundary conditions problematic in SPH simulations. In this work, we describe a robust and efficient adaptive thermal boundary condition algorithm. Our approach uses a straightforward free surface extraction algorithm. Once the free surface elements are found, the appropriate thermal boundary condition can be applied. We describe the SPH boundary formulation for the Dirichlet (defined temperature), Neumann (defined flux), and Robin (convection) boundary conditions. The algorithm is validated against the finite element method and an example of an industrial application, friction stir welding, is presented.

• Adetailedaircraft tyre finite element modellanding safety assessment for hard

  Hua Guo, Christophe Bastien, Mike V. Blundell, Gary Wood (Coventry University, Dunlop Aircraft Tyres Limited)

  Tyres have an important role in landing gear systems upon aircraft landing and taxing on the ground. The performances of an aircraft tyre under varied load conditions are vital requirements for aircraft safety certification. This paper describes the development of a detailed finite element (FE) model of an aircraft test tyre in order to investigate its performance and assess its safety criteria. The work follows the findings from previous researches [1] [2] [3] [4] and focuses on the aircraft tyre safety assessment under various loading scenarios that were not yet studied. Initially, tyre inflation and static load simulations have been analyzed based on a full-scaled 3D detail LS-Dyna® FE model, replicating the actual geometry and the correlated material properties from industrial experimental data. The dynamic simulations that aim to duplicate tyre load upon aircraft landing scenarios have also been analyzed. Following the comments from aircraft tyre industrial data and guidelines[5] [6], the dynamic simulations have covered the tyre loading scenario from on-road taxing, normal (soft) landing, hard landing to crash landing under different aircraft landing weights. The stresses on tyre/wheel contact areas and on bead cords have been chosen as the safety criteria. The simulation results, analysis and comments have been discussed in great details. The modelling and simulations described in this paper aim to demonstrate the effective use of FE models for aircraft safety assessment, by studying the criteria of the tyre for load cases corresponding with testing and operational scenarios. The development of such predictive model would allow the manufacturers to assess tyre availability during the design process, and also add to the general drive towards the use of more virtual prototypes in an area traditionally reliant on experimental testing.

• Adiabatic Shear Band Modeling in Inconel-718 Alloy

  Stefano Dolci, Kelly Carney, Paul Du Bois, Cing-Dao Kan (George Mason University)

  The failure mechanism for thick metal plates impacted by blunt projectiles is known as an adiabatic shear band (ASB), which results in a catastrophic failure due to concentrated shear deformation. ASB is generally considered to be a material or structural instability and as such is not controllable. ASBs are a thermodynamic phenomenon occurring at high strain rates and are characterized by large deformations, localized in a narrow band consisting of highly sheared material. Due to the extreme localization of the shear band it is difficult to model it using FEM, because the mesh size needed to capture it is often not practical for real applications. ASBs can control failures in ballistic impacts. For example, the strength characteristics of Inconel 718 are superior to those of Titanium 6Al4V, in quasi-static conditions. Hence, the ballistic limit for the same geometry plates of these materials should be very different. Unexpectedly, tests show that the materials have a similar ballistic limit for a 0.5” plate. The explanation for this similarity is that, inside the ASB the temperature rises to above 700°C, where Inconel undergoes a phase transformation that makes it brittle, causing a sudden failure. Ti6Al4V HPC lattice has a different microstructure than Inconel’s, and so its ASB behavior also differs. 2D analyses are presented, with progressively reduced element sizes until ASB appearance. ASBs of Inconel are shown to have a width of approximately 5 μm. This is far smaller than an element from an “industrial size” mesh. The elements of the mesh need to be smaller than the ASB width in order to capture the localization of shear and the consequent temperature rise in that region. As adiabatic shear band modeling exhibits a strong dependency on mesh size, we propose to neutralize the effects of different mesh dimensions by implementing a new regularization algorithm. The new algorithm will increase the amount of plastic work converted into heat as function of mesh size, where ASBs will occur. The updated model will replicate the ASB characteristics obtained with the ultra-fine 2D mesh using an “industrial size” mesh.

• Adiabatic Shear Band Modeling in Inconel-718 Alloy

  Stefano Dolci, Kelly Carney, Paul Du Bois and Cing-Dao Kan (George Mason University)

  The failure mechanism for thick metal plates impacted by blunt projectiles is known as an adiabatic shear band (ASB), which results in a catastrophic failure due to concentrated shear deformation. ASB is generally considered to be a material or structural instability and as such is not controllable. ASBs are a thermodynamic phenomenon occurring at high strain rates and are characterized by large deformations, localized in a narrow band consisting of highly sheared material. Due to the extreme localization of the shear band it is difficult to model it using FEM, because the mesh size needed to capture it is often not practical for real applications. ASBs can control failures in ballistic impacts. For example, the strength characteristics of Inconel 718 are superior to those of Titanium 6Al4V, in quasi-static conditions. Hence, the ballistic limit for the same geometry plates of these materials should be very different. Unexpectedly, tests show that the materials have a similar ballistic limit for a 0.5” plate. The explanation for this similarity is that, inside the ASB the temperature rises to above 700°C, where Inconel undergoes a phase transformation that makes it brittle, causing a sudden failure. Ti6Al4V HPC lattice has a different microstructure than Inconel’s, and so its ASB behavior also differs. 2D analyses are presented, with progressively reduced element sizes until ASB appearance. ASBs of Inconel are shown to have a width of approximately 5 μm. This is far smaller than an element from an “industrial size” mesh. The elements of the mesh need to be smaller than the ASB width in order to capture the localization of shear and the consequent temperature rise in that region. As adiabatic shear band modeling exhibits a strong dependency on mesh size, we propose to neutralize the effects of different mesh dimensions by implementing a new regularization algorithm. The new algorithm will increase the amount of plastic work converted into heat as function of mesh size, where ASBs will occur. The updated model will replicate the ASB characteristics obtained with the ultra-fine 2D mesh using an “industrial size” mesh.

• Adjusting the Contact Surface of Forming Tools in Order to Compensate for Elastic Deformations during the Process

  Knut Großmann, Hajo Wiemer, Andrè Hardtmann, Lars Penter, Sebastian Kriechenbauer - TU Dresden

  Nowadays, despite powerful simulation programs, the tool design process still contains manual and not reproducible work. In specific, the manual die spotting is mostly dependent on the workers experience and consumes a lot of time. A large potential to reduce time and costs is seen by decreasing the die maturing. The paper introduces an approach to obtain deep drawing tools from FE simulation with LS-DYNA, which need less additional manual maturing until good parts can be manufactured. Therefore, the current tool design process was analyzed and it was found out, that not properly assessing elastic tool and press properties in FE simulations in one of a the causes that lead to additional die spotting effort. Hence, a methodology was developed to compensate for the effects of those elastic properties. Depending on their intensity, afore mentioned machine and tool properties are included in the FE model. Based on former research work at the IWM the effects of elastic deformations and dislocations of the die surface on the final shape of the part are calculated. Derived from the calculated deformations, a transformations matrix is calculated and a new die surface is obtained after a few iterations. The new die surface has the same shape under load like the initial die surface without load. The new method was tested through an experimental set-up, which allowed an excessive deformation of the die under load. This experiment does not reflect the reality but serves for general demonstration purposes of the compensation approach. As expected the simulation and experiment show a massive impact of the die deflection on the draw-in of the manufactured part. The die deformation affects the distribution of the blankholderforce on the part. It was found a higher pressure on the die corners and lower pressure in the centre. By means of the compensation method, the die surface was adjusted to achieve that the die surface under load is the same as the initial surface without deformations. The experiments show that the final shape of the part, which was drawn with the compensated die, is very close to the shape, which was predicted without calculating the die deformation.

• Adjusting the Contact Surface of Forming Tools in Order to Compensate for Elastic Deformations during the Process

  Knut Großmann, Hajo Wiemer, Andrè Hardtmann, Lars Penter, Sebastian Kriechenbauer - TU Dresden

  Nowadays, despite powerful simulation programs, the tool design process still contains manual and not reproducible work. In specific, the manual die spotting is mostly dependent on the workers experience and consumes a lot of time. A large potential to reduce time and costs is seen by decreasing the die maturing. The paper introduces an approach to obtain deep drawing tools from FE simulation with LS-DYNA, which need less additional manual maturing until good parts can be manufactured. Therefore, the current tool design process was analyzed and it was found out, that not properly assessing elastic tool and press properties in FE simulations in one of a the causes that lead to additional die spotting effort. Hence, a methodology was developed to compensate for the effects of those elastic properties. Depending on their intensity, afore mentioned machine and tool properties are included in the FE model. Based on former research work at the IWM the effects of elastic deformations and dislocations of the die surface on the final shape of the part are calculated. Derived from the calculated deformations, a transformations matrix is calculated and a new die surface is obtained after a few iterations. The new die surface has the same shape under load like the initial die surface without load. The new method was tested through an experimental set-up, which allowed an excessive deformation of the die under load. This experiment does not reflect the reality but serves for general demonstration purposes of the compensation approach. As expected the simulation and experiment show a massive impact of the die deflection on the draw-in of the manufactured part. The die deformation affects the distribution of the blankholderforce on the part. It was found a higher pressure on the die corners and lower pressure in the centre. By means of the compensation method, the die surface was adjusted to achieve that the die surface under load is the same as the initial surface without deformations. The experiments show that the final shape of the part, which was drawn with the compensated die, is very close to the shape, which was predicted without calculating the die deformation.

• Advance in Sheet Metal Forming - One-step Solution, Multi-Beads, Gravity Prebending, Auto Nets, and Local Compensation

  X. Zhu, L. Zhang (LSTC)

  Some of the new features developed since the last conference will be discussed. 1)A fast one-step sheet metal forming program Developed mostly for blank size estimation and forming effect initialization in crash simulation, this powerful feature allows hundreds of parts to be simulated in a very short time. 2)An improvement to the contact draw bead Developed together with Ford Motor Research and Advanced Engineering Laboratory, multiple beads can now be generated automatically based on the base draw bead definition, to represent the actual bead width and forces. This more realistic approach allows for a better blank size prediction and utilization. 3)Pre-bending for gravity simulation Developed together with Ford Motor Company, blanks can now be pre-bent to simulate the various scenarios of stamping press destacker loading of the sheet blank to the draw die. This new approach produces a more realistic gravity-loaded blank shape, resulting in shorter die travel and better stamping quality. 4)Automatic fixture nets for free-standing springback simulation This feature allows for automatic generation of fixture nets of user-specified sizes, in user specified locations, with contacts automatically established, for a free-standing springback simulation. 5)Springback compensation for localized multi-regions Developed together with Chrysler LLC, local compensation of stamping dies can be extended to multiple regions.

• Advance in Sheet Metal Forming - Failure Criteria, Friction, Scrap Trimming and Adaptive Meshing

  L. Zhang, X. Zhu (LTSC)

  Some of the new features developed since the last conference will be discussed. 1)Directional and pressure sensitive friction model for metal forming Developed together with Ford Motor Research and Advanced Engineering Laboratory, this feature enables definition of Coulomb frictions in any directions in the sheet plane. The friction coefficients can also be scaled based on the contact pressure incurred during the stamping process. 2)Failure criterion for the non-linear strain path for *MAT_036 Developed as a part of the ASP-NSP project, the previously known Formability Index (F.I.) is now implemented together with *MAT_036. Verification of the model will be discussed. 3)Contact-based scrap trimming function Developed together with Ford Motor Company, this powerful feature allows realistic scrap trimming simulation and contact-based kinematic and dynamic transfer from the trim steels to the trimmed scraps. 4)Pre-adaptive along curves for line-die simulation Developed together with Chrysler LLC, a region of user specified size can now be defined for mesh adaptivity along a curve for subsequent line-die simulation.

• Advanced Finite Element Model for AE-MDB Side Impact Barrier

  M. Asadi , P. Tattersall - Cellbond Composites Ltd., B. Walker - ARUP Campus (UK), H. Shirvani - Anglia Ruskin University (UK)

  This paper represents a new Finite Element simulation model for AE-MDB v3.9 side impact barrier and proposes a method on creating suitable assumptions and material data. Cellbond AE-MDB barrier investigation was carried out to produce an advanced FE model. Experimental Flat Wall and Offset Pole test results were used to validate the accuracy of the developed models. The explicit LS Dyna 3D code was used to model the geometries, and the Material Card data was obtained from several static compressive tests at different angles to characterize the yielding function of the aluminum honeycomb parts. The dynamic models were also validated by a Flat Wall test which represents the crash performance of AE-MDB barrier. For dynamic tests the barrier was mounted on a mobile trolley and it was tested at speed of 35 km/h. In Offset Pole test, the AE-MDB barrier was subjected to an asymmetric crush with a rigid vertical pole in which test speed was 20 km/h. The final comparison of the overall results demonstrates a good correlation between test data and CAE results for both the Flat Wall and Offset Pole tests.

• Advanced Mode Analysis for Crash Simulation Results

  Clemens-August Thole

  Potential scatter of simulation results caused for exampleby buckling, is still a challenging issue for the predictability. Principle component analysis (PCA) is a well-known mathematical method for data analysis. In order to characterize scatter PCA analysis was applied to the simulation results from a number of runs using all node positions at all time steps. For industrials relevant problems the size of the data base is larger than 100 GBytes (even, if compressed by FEMzip1[7]) . As a result the major components dominating the differences between the simulation results are available. Since PCA is a mathematically based method, the selected modes do not separate different physical effects like buckling at different parts of the model. PCA rather tries to maximize the variations by combining several physical effects into one mode. Difference PCA(DPCA) applies PCA analysis to the results for each part and time step. By analysis of the related covariance matrices, the local dimension of the scatter subspace can be identified and correlation between the scatter at different places can be analyzed. Using DPCA, different origins of scatter can be identified and physically meaningful components can be determined. The paper introduces the approach and shows results for an industrial model.

• Advanced Modeling and Drop Simulation With New Features of LS-DYNA

  Jason Wu

  Phone drop simulation is an important application of LS-DYNA in electronics industry. The application has been widely used in all leading companies to produce electronic handsets, like Nokia, Motorola, and Samsung. Since more new features complemented in 970 version of LS-DYNA, phone modeling and drop simulation strategy has changed a lot to obtain more accurate and quick results. This paper introduces new methods, and recent development of phone modeling and drop simulation, based on author’s experiences in recent years. The paper is focused on using right element type in LS-DYNA element library and some new strategies to establish better phone model and drop simulation. The paper provides benchmarks to verify the modeling strategies. The paper still gives an example for advanced application of LS-DYNA in multiply impact simulation.

• Advanced MPP Decomposition of a SPH Model

  Christian MOUTELIERE, Vincent LAPOUJADE (DynaS+), Antoine MILLECAMPS (SNECMA)

  SPH, Smoothed Particle Hydrodynamics, is a very efficient tool to model industrial problems where large deformations occur. However, one disadvantage of the SPH technique is the relative expensive cpu cost compared to standard Finite Elements. Using the MPP version of LS-DYNA® allows users to handle larger problems (up to more than millions of particles) in a reasonable time. Due to the meshfree nature of the SPH method, standard decompositions used for finite elements can sometimes lead to very bad speed-up of the code. Users have to be aware of some options and rules to define customized decompositions in order to minimize communications between processors and get very good load balancing. Two classes of models are presented for addressing all possible situations with respect to optimizing MPP decomposition of a calculation based in whole or in part on the SPH technology. The first one is a pure SPH model of a high velocity impact of a sphere on a plate. The second one is a coupled FE-SPH model of a bird impacting a set of fan blades of an engine. Two versions of the same problem will be studied: for the first, shell elements are used for the modeling of fan blades whereas for the second, solid elements are used.

• Advanced Pedestrian Legform Impactor (aPLI)

  Katharina Stielau (CDH AG), David Blauth (ATD-MODELS GmbH)

  Pedestrian protection aims to reduce injuries in car-to-pedestrian impacts. It is the subject of increasingly stringent worldwide statutory and consumer rating requirements and is thus increasingly important in current vehicle development. With electric vehicles, which are not always readily noticed by pedestrians, there is an even higher risk of pedestrian injury. Passive pedestrian protection is, active safety systems notwithstanding, the final countermeasure to reduce serious and fatal pedestrian injury. The current test assessment for pedestrian protection uses three “impactors” in different loading scenarios designed to represent injuries to specific parts of the human body, such as the head, the upper leg and the lower leg. Recent development of the Advanced Pedestrian Legform Impactor (aPLI) focuses on enhanced biofidelity of the lower extremities to address long-bone fractures, knee ligament injuries and pelvis fractures in a single impactor instead of the separate, independent, lower leg and upper leg impactors. To date, the requirements for the aPLI are applied to the EuroNCAP 2022 regulations. But as seen with the previous development of the FlexPLI, it is to be expected that the global statutory requirements will be influenced by global consumer rating requirements. The CAE development process focuses on high accuracy simulations within the vehicle development process, using reliable and robust FEM vehicle and impactor models. The aPLI-FE models represent the Cellbond aPLI SBL-A hardware and have been developed in close cooperation with the hardware manufacturer. Utilizing many years of experience in the field of occupant protection with HIII models, the FE model ATD-aPLI was also developed with extensive feedback from partners in the German automotive industry. Special modelling techniques were developed and applied in LS-DYNA®. The ATD-aPLI model was validated by material and component investigations and by experiments in generic test rigs. Models for future hardware versions will be released regularly in preproduction and final versions. Automotive manufacturers face new challenges in the CAE process and hardware tests using the new aPLI. Despite similarities with the previous FlexPLI, the attached upper body mass of the aPLI has a strong influence on the impactor kinematics and particularly the femur load. This paper highlights some characteristics of the aPLI and describes a sensitivity analysis using LS-DYNA within the framework of a typical CAE development process.

• Advanced Plasticity & Fracture for Structural Car Body Metals in Crashworthiness CAE analysis: SAMP-1 plus GISSMO

  Alejandro Domínguez, Pablo Cruz, Lluis Martorell, Adrián Ros, Eduardo Martin-Santos

  This paper describes an engineering process to generate material cards for forefront crashworthiness CAE analysis that properly capture both plastic and fracture behaviour of car body structural metals. The main objective of the paper is to show that advanced plasticity approaches can be used without significantly increasing the complexity of the overall material characterization process. The paper is mainly centred in metals plastic characterization for shell elements although some important relationships with the fracture characterization will be also discussed. Before defining the engineering process, it is necessary to tackle some misleading general ideas that the automotive CAE community normally assumes as correct for metals like steel or aluminium alloys.

• Advanced Results Databases Compression Techniques to Allow their Efficient Use in Results Data Management Systems

  Antonis Perifanis, Stelios Karapantazis, Dimitrios Krontsos, BETA CAE Systems S.A.

  The usage of automated post processes is the rule nowadays. Simple scenarios include saving only specific LS-DYNA® results in post processing software native databases whereas in more sophisticated cases a series of report data are stored in data management systems. New challenges arose this way relevant to the need to download the report data from a data server as quickly as possible, display and compare them in the best way allowing in the same time as much access to the original results data as possible.

• Advanced Simulation Methods for the new Porsche Panamera

  F. Sautter, H. Hogenmüller - Dr.-Ing. h.c. F. Porsche

  The Porsche Panamera brings together for the first time the virtues of a sports car with Porsche’s own interpretation of a classical Gran Turismo. This new segment is characterised by the balance between sportiness on the one hand and comfort, luxury and long-range touring characteristics on the other. The fact that the development was new, with no previous model available to use as a basis for vehicle parameters and characteristics, created a significant challenge. To meet the requirements of a reliable, target-oriented vehicle development, major emphasis was placed on virtual development tools. Advanced simulation methods found their application in the early concept definition, and were integrated into the complete vehicle development process. The CAE tools and methods were also developed further during the project to meet the specific project needs. The following paper demonstrates these points using the example of design for passive safety. The paper describes the new Digital Product Development Process, with its centrally managed multi- disciplinary Digital Protoypes, which was introduced for the Panamera project. Furthermore, a selection of the CAE tools used in the development of the Panamera and their evolution are discussed. The main focus of the CAE tools was to accelerate and provide a qualitative improvement to the product development process.

• Advanced Simulation Methods for the new Porsche Panamera

  F. Sautter, H. Hogenmüller - Dr.-Ing. h.c. F. Porsche

  The Porsche Panamera brings together for the first time the virtues of a sports car with Porsche’s own interpretation of a classical Gran Turismo. This new segment is characterised by the balance between sportiness on the one hand and comfort, luxury and long-range touring characteristics on the other. The fact that the development was new, with no previous model available to use as a basis for vehicle parameters and characteristics, created a significant challenge. To meet the requirements of a reliable, target-oriented vehicle development, major emphasis was placed on virtual development tools. Advanced simulation methods found their application in the early concept definition, and were integrated into the complete vehicle development process. The CAE tools and methods were also developed further during the project to meet the specific project needs. The following paper demonstrates these points using the example of design for passive safety. The paper describes the new Digital Product Development Process, with its centrally managed multi- disciplinary Digital Protoypes, which was introduced for the Panamera project. Furthermore, a selection of the CAE tools used in the development of the Panamera and their evolution are discussed. The main focus of the CAE tools was to accelerate and provide a qualitative improvement to the product development process.

• Advanced Simulation of Polymer Composite SMC Compression Molding using Fluid-Structure Interaction in LS-DYNA®

  Dominic Schommer, Miro Duhovic, Florian Gortner, Martin Maier (Institut für Verbundwerkstoffe GmbH)

  Thermoset Sheet Molding Compounds (SMC) are becoming more and more popular as lightweight construction materials in the automotive industry. SMC compression molding is a forming process in which a pre-cut SMC-Prepreg is placed within a heated mold and is first pressed into shape before being cured. By closing the mold, the thermoset resin is forced to flow and takes the randomly orientated fiber reinforcement present, along with it. The flow behavior of the SMCs can be characterized by press rheometry. In a typical press rheometry test, certain data recorded during the test, specifically press force, tool closing speed, position and time together with the known tooling geometry (plate surface area), are used to develop and verify a finite element characterization model in LS-DYNA using the relevant Arbitrary Lagrange Eulerian (ALE) capable material model. In this work, the Fluid Structure Interaction (FSI) capabilities in LS-DYNA are used to model the flow ability of the SMC material. No independent effects of the resin cure on the materials rheology are taken into consideration. The characteristic data obtained from the real press rheometry tests are used to calibrate the material model so that it can be used to predict the mold filling behavior of more complex tooling scenarios. As an example for forming a complex real part, the compression molding of a ribbed automotive spoiler test part is analyzed upon complete closing of the mold. The goal of the simulation is to provide information about the suitability of the tooling design geometry and the processing parameters. A simplified two dimensional model of the ribbed automotive spoiler part shows, that the unrecognized effects inside the material cause a failure in the simulation in certain situations. A future version of the model should make it possible to analyze the nature of the SMC part, more specifically, the flow profile, fiber orientation and resulting volume fraction in the individual sections of the part, in particular the rib section, along with chemical curing of the resin.

• Advanced Simulations of Cellular Structures with LS-DYNA

  Matej Vesenjak, Zoran Ren - University of Maribor

  Cellular structures have an attractive combination of physical and mechanical properties and are being increasingly used in modern engineering applications. In this study the influence of different parameters (type of base material, type of pore filler, relative density, size of the cellular structure, strain rate) on behaviour of open- and closed-cell cellular structures under impact loading was investigated by means of computational simulations using the explicit finite element code LS-DYNA. The influence of gas filler inside the closed-cell cellular structure was analysed using the representative volume element and the airbag model. The analysis of the fluid filler behaviour inside the opencell cellular structures was done with combination of the Finite element method and the Smoothed particle hydrodynamics meshless method. The base material properties and macroscopic behaviour of cellular structures with and without fillers were determined with experimental measurements of appropriate specimens under quasi-static and dynamic uniaxial loading conditions. Computational simulations show that the base material has the highest influence on behaviour of cellular structures under impact conditions. The increase of relative density and strain rate results in increase of the cellular structure stiffness. Parametric computational simulations have also confirmed that the filler influences macroscopic behaviour of the cellular structures, which depends on the loading type and the size of cellular structure. In open-cell cellular structures with higher filler viscosity and higher relative density, increased impact energy absorption is observed.

• Advancements in Eigenvalue Technology

  Daniel Bielich, Roger Grimes, Francois-Henry Rouet

  The standard eigenvalue problem for Implicit Mechanics in LS-DYNA is ΚΦ = ΜΦΛ , where Κ and Μ , the stiffness and mass matrices, are real and symmetric positive semi-definite in most applications. LS-DYNA offers three main algorithms for this problem, chosen with EIGMTH (field 7 of line 1 of *CONTROL_IMPLICIT_EIGENVALUE). The three algorithms currently available are • Lanczos (EIGMTH=2); • LOGPCG (EIGMTH=102); • Fast Lanczos (EIGMTH=103). This paper will give an overview of these methods, guidelines on when each should be used, performance comparisons, and recent enhancements. For non-symmetric problems, LS-DYNA also has an SMP solver, which relies on ARPACK [1,2]. An MPP solver relying on a different algorithm is being actively developed and is briefly mentioned in the last section.

• Advancements in Material Modeling and Implicit Method for Metal Stamping Applications

  Xinhai Zhu, Li Zhang - Livermore Software Technology Corporation

  A review of recent developments in stamping manufacturing will be conducted. The review will be focused on discussions surrounding new features related to static implicit binder wrap, advanced material modeling with Yoshida’s non-linear kinematic hardening in conjunction with Hill’s 1948, Barlat 1989 and Barlat 2000 yield criteria.

• Advances in Adaptive Thermal-mechanical Metal-forming Simulations in LS-DYNA

  Rudolf Bötticher - TMB GmbH

  The vision of LS-DYNA is to become multiphysics and adaptive. LSTC endeavours to make the LS-DYNA code as complete, accurate and easy to use as possible. This contribution evaluates the features for adaptive thermal-mechanical simulations that are in recent LS-DYNA versions with a focus on implicit 3D. Implicit solutions do not need mass scaling as explicit forming simulations often use. Implicit element free Galerkin (EFG) elements are successfully used for a bulk metal forming test case (upsetting with a non-trivial stamp) with adaptive remeshing of tetrahedrons. The interplay of adaptive remeshing with the contact algorithm is highlighted. Additionally plastic heating of 3Dshells in a deep drawing benchmark example is assessed Some remarks regarding the features for post-processing adaptive simulations with full remeshing in LS-PrePost are evaluated.

• Advances in Fatigue Analysis with LS-DYNA

  Yun Huang, Zhe Cui, Livermore Software Technology Corporation

  Fatigue analysis is critical to the design and optimization of metal structures and components. This paper reviews the recent development in fatigue analysis with LS-DYNA. Both frequency domain and time domain fatigue solvers have been implemented to LS-DYNA. They can be used towards different simulation situations. Some examples are provided in this paper, to illustrate how to use these fatigue analysis methods. The plan on future development of the fatigue solvers in LS-DYNA, is also discussed.

• Advances in IGA for Sheet Metal Forming Applications

  S. Hartmann (DYNAmore); D. Benson (LSTC); A. Nagy (LSTC)

  In the last years, Isogeometric Analysis (IGA) has become very popular in the scientific research community. Various types of basis functions are investigated by the researchers, while the most widely used geometry representation in the Computer-Aided-Design (CAD) community is based on NURBS. It has been shown, that NURBS are particularly well suited for finite element analysis leading to qualitatively more accurate results in comparison with standard finite elements based on Lagrange polynomials. This work will give a short overview about the general possibilities of IGA with NURBS in LS-DYNA and focus on the recent advances for the analysis of Sheet Metal Forming Applications. Therefore the benchmark example from the Numisheet 2005 conference on “Forming of an Automotive Underbody Cross Member” (BM2) [1], which has been analyzed by Hartmann et al. [2] in 2011 using one of the first IGA implementations in LS-DYNA, is reanalyzed to demonstrate the progress made since then.

• Advances in LS-DYNA ® Metal Forming (I)

  Xinhai Zhu, Li Zhang and Yuzhong Xiao (LSTC)

  Some of the new features developed since the last conference will be discussed. 1) Movable adaptive fission/fusion box The movable fission/fusion box is an essential enabler in completing a simulation in a efficient manner, especially in cases where deformation is relatively localized. Related keywords include: *CONTROL_ADAPTIVE, *DEFINE_BOX_ADAPTIVE. 2) Checking fixture clamp definition and simplification of FORMING contact definition The keywords, *DEFINE_FORMING_CLAMP, *DEFINE_FORMING_CONTACT, are created to ease the user definition of checking fixture clamps and contacts definition. 3) New options in *INTERFACE_BLANKSIZE Additional features under this keyword allow users to include/exclude a particular trim lines and to define symmetric conditions for the part, using keywords: *INTERFACE_BLANKSIZE_SCALE_FACTOR, *INTERFACE_BLANKSIZE_SYMMETRIC_PLANE. 4) Some major improvements to *CONTROL_FORMING_SCRAP_FALL In conjunction with the Ford Motor Company, the original “Constraint Release” method is evolved into the “Scrap Trimming” method, making the scrap trimming and fall simulation much more closer to reality. 5) 2D and 3D trimming of solids and laminates An important feature in metal forming simulation using solid elements and laminates, 2D and 3D trimming are now available. 6) Automatic offset of tool element/node IDs The creation of the keyword *INCLUDE_AUTO_OFFSET enables user to offset individual tools with overlapping element/node IDs, allowing the user to bypass a metal forming GUI when updating just one or two tooling pieces. 7) Positioning of unfolded blank in one-step simulation Allows user to specify three points used to position the unfolded blank relative to the part’s initial position and orientation..

• Advances in LS-DYNA ® Metal Forming (II)

  Xinhai Zhu, Li Zhang and Yuzhong Xiao (LSTC)

  Some of the new features developed since the last conference will be discussed. 1) Implementation of Stoughton’s Non-Associate Flow Model (*MAT_260A) Strain rate sensitive, non-associated flow material model suitable for metal forming simulation. 2) Implementation of Mohr’s Non-Associate Flow Model (*MAT_260B) Strain rate sensitive and temperature softening effect coupled with a non-associated flow rule, combined with a ductile fracture model based on Hosford-Coulomb fracture initiation model, suitable for metal forming and crash simulation. 3) Best fitting of meshed (including STL) parts with *CONTROL_FORMING_BESTFIT Correlation study of simulated springback with scanned STL file made easy. 4) Tool mesh checking/fixing and physical offset of tools (*CONTROL_FORMING_AUTOCHECK) This feature fixes tooling meshes arising from bad tool CAD surfaces, automatically make tool normal consistent and in required orientation, and offsets the tool mesh to create an opposite side of the tool. 5) Formability Index (F.I.) extension to *MAT_036, *MAT_125 and *MAT_226). Predictions of sheet metal failure under non-linear strain paths are extended to aforementioned material models. 6) Implementation of a Cyclic Fatigue Modeling (*MAT_165B) A mixed isotropic and kinematic hardening model suitable for small strain cyclic fatigue modeling.

• Advances in LS-DYNA® for Metal Forming (I)

  Xinhai Zhu, Li Zhang, Yuzhong Xiao, HouFu Fan, Livermore Software Technology Corporation

  • Enhancements in *CONTROL_FORMING_ONESTEP • Smoothing of strain ratio (β) for failure prediction under nonlinear strain paths, with * CONTROL_ FORMING_TOLERANC • “Soft 6” contact improvement for gage pin contact • Weld line mapping with *INTERFACE_WELDLINE_DEVELOPMENT • Improvements in *BOUNDARY_SPC_SYMMETRY_PLANE (SET) • Improvements in springback compensation • Improvements in *ELEMENT_LANCING

• Advances in LS-DYNA® for Metal Forming (II)

  Li Zhang, Xinhai Zhu, Yuzhong Xiao, HouFu Fan, Livermore Software Technology Corporation

  • New features in state output with *CONTROL_FORMING_OUTPUT • Automatic change from shell to thick shell elements with *CONTROL_FORMING_SHELL_TO_TSHELL • Define material hardening behavior in LS-DYNA with *DEFINE_CURVE_STRESS • Uniform mesh refinement inside a curve loop with *CONTROL_ADAPTIVE_CURVE • Vector option in *CONTROL_FORMING_BESTFI, and LS-PrePost® 4.5 Best-fit GUI • Sandwiched part mesh adaptivity • New capabilities in 2D and 3D trimming of solids, laminates, and 2D trimming of TSHELL

• Advances in LS-DYNA® Metal Forming (II)

  Li Zhang & Xinhai Zhu (LSTC)

  Some of the new features developed since the last conference will be discussed. 1) Lancing – instant and progressive Cutting of sheet metal during forming to alleviate thinning and splits. 2) Auto close of open trim curve loop Improvement in trimming simulation by automatically closing an open trim curve. 3) Tailor-rolled blank thickness specification Specification of thickness field of a tailor-rolled blank for any ensuing simulation. 4) Springback compensation referencing original tool mesh Compensation using the original tool mesh for iterations to improve tool surface geometry. 5) Springback compensation – for small part shape change Compensation made easier for those parts with small shape changes that do not affect springback results. 6) Simulation-based blank size optimization A significant development in blank size and trim line optimization of stamping dies.

• Advances in LS-DYNA® Metal Forming (I)

  Xinhai Zhu & Li Zhang (LSTC)

  Some of the new features developed since the last conference will be discussed. 1) Gaging pin contact improvement New contact treatment for edge contact between gaging pin and sheet blank edge during gravity loading. 2) Output control for parameterized input Specifying D3PLOT and INTFORC outputs made easy for parameterized input. 3) Gravity loading – switching between implicit dynamic and implicit static Taking advantage of the best of both dynamic and static methods. 4) Polygon adaptive box A more flexible adaptive remeshing control. 5) Maximum ID specification for blank adaptive remeshing Setting starting element and node ID for an adaptive blank in a line-die simulation. 6) Flange unfolding Unfolding of deformable flanges onto addendum for trim line development.

• Advances in Simulating Corrugated Beam Barriers under Vehicular Impact

  Akram Abu-Odeh (Texas A&M Transportation Institute)

  W-beam guardrail systems are the most common roadside railing systems used by many road authorities worldwide. They have been used for decades as roadside barrier to protect errant vehicles from intruding into hazardous areas. This paper gives a description of this rail system and recent methods to simulate its performance under roadside impacts. The availability of simulation technologies such as LS-DYNA® makes it possible to evaluate the performance of guardrail systems under given impact condition. A predictive simulation example and a subsequent crash test are presented as how simulation can be integrated into roadside safety hardware design process.

• Advances in Simulating the Processing of Composite Materials by Electromagnetic Induction

  M. Duhovic, P. Mitschang, M. Maier (Institut für Verbundwerkstoffe GmbH, Germany), I. Caldichoury, P. L'Eplattenier (LSTC)

  In the previous installment of this work, a flat spiral "pancake" type coil geometry and two different plate material types with large differences in electrical and thermal conductivity (structural steel and carbon fiber reinforced polymer composite) were used to perform static plate induction heating characterization experiments for the purposes of characterizing the heating behavior of both materials in preparation for continuous induction welding simulations. The static plate heating tests were validated experimentally in two Finite Element Analysis (FEA) software codes including LSTC's LS- DYNA® 980 (R7) solver. Following on from this initial work, a simulation test-bed has been created in order to study the continuous induction welding of two joining partners. The simulation test-bed mimics an experimental setup developed at the Institut für Verbundwerkstoffe (IVW) GmbH which considers a two-dimensional joining setup (two flat overlapping plates) and allows a more complete investigation of the thermal behavior that occurs during a continuous induction welding process. 3D surface plots of the top surface temperatures which are generated across the entire width of the joint as well as along its length can be investigated for different welding speeds and induction welding processing parameters. More importantly, the same types of surface plots can also be generated at the joining interface providing a complete view of the temperature profile that occurs during the process at this important location. This information can be used to decide on the optimum processing parameters to ensure that the material anywhere at the joining interface always remains within its prescribed upper and lower processing temperature limits. With its three-way physics coupling, the simulation test-bed also allows the consideration of further processing parameters including the influence of roller contact and additional top surface cooling via a moving air-jet nozzle for different induction welding speeds.

• Advances in the Measurement and Modeling of Plastics for Impact Simulations

  Hubert Lobo - DatapointLabs

  High strain-rate properties have many applications in the simulation of automotive crash and product drop testing. These properties are difficult to measure. Previously, we described a novel inferential technique for the measurement of the properties of polycarbonate. In this paper, we demonstrate that the technique appears to work for a variety of polymers. We also show that plastics exhibit different kinds of high-strain rate behaviors. It is important to use an appropriate LS-DYNA material model for valid simulation results.

• Advances on the Incompressible CFD Solver in LS-DYNA

  Facundo Del Pin - Livermore Software Technology Corporation

  The present work will introduce some of the resent developments in the Incompressible CFD (ICFD) solver currently under development in LS-DYNA. The main feature of this solver is its ability to couple with any solid model to perform Fluid-Structure interaction (FSI) analysis. Highly non-linear behavior is supported by using automatic re-meshing strategies to maintain element quality within acceptable limits. In this work we will introduce the additional features for conjugate heat transfer, turbulence model, biphasic flow, some new feature in terms of mesh generation like boundary layer meshing and MPP.

• Advancing Solder Joint Modeling in PCBs: A Two-Scale Co-Simulation Approach for Shock & Vibration Analysis Using LS-Dyna

  Henan Mao, Dandan Lyu, Tieyu Zheng, Wei Hu

  The integrity of solder joints in PCBs under dynamic loading conditions is critical for the reliability of electronic devices. Traditional modeling methods, such as representing solder joints with beam elements or solid elements in one-scale simulations, often face trade-offs between computational efficiency and accuracy. In this study, we introduce a two-scale co-simulation approach using LS-Dyna to address this challenge and provide both accuracy and efficiency in PCB analysis.

• Ageing Effect on Crashworthiness of Bus Rollover

  A.H. Iskandar, Q.M. Li (University of Manchester, UK)

  International standards related to protection of occupants in rollover accidents are generally applied on new vehicles and regulated for design approval. However, there is no standard regulation governing rollover crash performance of aged vehicles and no proper systematic test to monitor it. It is known that vehicle structural integrity deteriorates after years of operation undergoing various service environments and conditions. The scenario is worsen if the vehicle is poorly maintained and still in operation beyond its lifespan. These factors directly influence the vehicle crashworthiness level and affects its safety. The present paper attempts to show how ageing factors like corrosion and deterioration of mechanical properties may change the overall vehicle structural strength and hence its crashworthiness performance. As a case study, rollover analysis according to European standards (UNECE R66) was set up on a finite element bus model using LS-Prepost and simulation was performed using LS-DYNA . Different levels of condition due to ageing effect were included in the model to examine the changes of rollover performance of the bus. Aged bus rollover studies from real world crashworthiness investigation in Malaysia were referred for comparison to support the argument. Result shows that ageing factors directly influence the performance of vehicle crashworthiness.

• Agenda.pdf
• Agile Dummy Model Development Illustrated by Refinement Activities of the WorldSID Shoulder Model

  R. Brown, G. Stokes (Jaguar Land Rover), U. Franz, S. Stahlschmidt (DYNAmore)

  The Agile Software Development is a method that promotes adaptive planning, evolutionary development, early delivery, continuous improvement, and encourages rapid and flexible response to changes. This method is established in the development of software and influences also many other development processes. The employees at DYNAmore are developing dummy models together with a consortium of car companies since decades. The models are used world wide by almost all automotive companies that run LS-DYNA to design their restraint systems.

• Aid Design Die of Auto-Body Using Numerical Simulation of 3-D Sheet Metal Forming Processes

  Ninig-an Hu, Ning-yan Zhu - SAE China (Society of Automotive Engineering of China)

  It has been well applied in automotive manufacture of China about the technology of the numerical simulation of 3-D sheet metal forming processes during the recent years. Besides helping tool designers and artificers find optimal shapes of technical surface on the die, DYNAFORM is used in the early stages of the auto-body to work over the formability of various parts. In addition to the stamping process, the new forming technologies can be analyzed with DYNAFORM to find more efficient methods and optimal processing parameters for parts of the auto-body. The paper discussed how DYNAFORM is used to select a critical part in my plant and demonstrated how numerical simulation can reduce the developing time and costs of tools. For example, the formability analysis for the drawing die of the inside rear door on the car was performed using the numerical simulation of 3-D sheet metal forming processes. It is well known that the occurrences of both fracture and wrinkle were the two encountered difficulties in the stamping process. The numerical simulation was performed to analyze the metal-flow that caused the fracture and wrinkle on the draw-bead and it also acted to analyze the change of the blank’s outline that could bring up the fracture or wrinkle. The strain distributions were obtained from the numerical simulations and were also used in conjunction with the forming limit diagram to predict the onset of the fracture. The effect of blank-holder pressure and friction on the occurrence of the fracture and wrinkle was researched. To prevent the formation of the fracture and wrinkle, according to the above formability analysis of the numerical simulation, an optimum shape of the technical surface, the draw-bead distribution and sizes on the drawing die surface and the blank’s outline were finally determined.

• Air Blast Reflections and Angle of Incidence

  Len Schwer (SE&CS)

  The Unified Facilities Criteria 3-340-02 provides blast wave reflection ratios as a function of angle-of-incidence as Figure 2-193. However no text is provided indicating the source of this information. A knowledgeable source provided that the figure combines experimental and analytic results. In an effort to assess the UFC information, comparisons are made two different sets of small scale experiments and LS-DYNA Eulerian simulation results. These comparisons are agree fairly well with UFC except in the region of the critical angle-of-incidence where there are large differences. Of interest to LS-DYNA users, the comparison also includes the simple analytical expression for reflection ratios as a function of angle-of-incident proposed by Randers-Pehrson and Banister, and used in the LS-DYNA algorithm Load Blast Enhanced. It is shown that the Randers-Pehrson and Banister representation of reflection ratios is a lower bound on the above mentioned experiments and LS-DYNA simulations.

• Airbag Folding for LS-DYNA using Generator4

  L. Benito Cia (GNS)

  Generator4 is a preprocessor that helps users modeling the most complex CAE designs, from geometry handling and meshing to simulation definition. Characterized by its flexibility, this multi-platform software allows engineers to define calculations for the finite element solver LS-DYNA®, as well as for multiple other solvers. Airbag modeling represents a great challenge for CAE Engineers, where complex processes with high accuracy demands are combined with short cycle times. In order to ease up engineers work at the airbag optimization field, Generator4 includes the Pre-Simulation module.

• Airbag Folding with Generator4 and LS-DYNA® a Generic Process

  Leyre Benito Cia, Christoph Kaulich, GNS-mbH (Gesellschaft für Numerische Simulation)

  Generator4 is a pre-processor that helps users modeling the most complex CAE designs, from geometry handling and meshing to simulation definition. Characterized by its flexibility, this multi-platform software allows engineers to define calculations for the finite element solver LS-DYNA, as well as for multiple other solvers. Airbag modeling represents a great challenge for CAE Engineers, where complex processes with high accuracy demands are combined with short cycle times.

• Airbag Folding with JFOLD Latest Developments and Case Studies

  Richard Taylor, Ove Arup & Partners International Limited;, Toru Ishizuka, Mayumi Murase, Shinya Hayashi, JSOL Corporation

  JFOLD is a software tool for simulation based airbag folding in LS-DYNA®. Today’s airbag deployment analysis demands accurate folding of complex designs, but this is often a very time consuming process requiring expert input. JFOLD’s continuous development focuses on making the process simpler and quicker and to give the non-expert access to complex folding techniques. This is achieved through three core elements: intuitive user interface, built-in customisable tool libraries and realistic, state of the art examples and tutorials.

• Airbag Folding with JFOLD - Latest Developments and Case Studies

  R. Taylor (ARUP); S. Hayashi (JSOL)

  JFOLD is a software tool that helps users perform simulation based airbag folding in LS-DYNA. Today’s airbag deployment analysis demands accurate folding of complex designs, but this is often a very time consuming process requiring expert input. JFOLD’s continuous development focuses on making the process simpler and quicker and to give the non-expert access to complex folding techniques. This is achieved through three core elements: intuitive graphical interface, built-in customisable tool libraries and realistic, state of the art examples and tutorials. Our presentation will describe a driver’s airbag case study of two folding patterns with deployment validation using CPM. Two methods of folding a passenger airbag will also be shown, including and a novel way to quickly flatten the bag from 3D to 2D. To further reduce airbag development cycle times and cost, a new airbag morphing application is under development to help the user optimise the design in a virtual environment. This and other new features will be presented.

• Airbag Inflator Models in LS-DYNA ®

  Kyoung-Su Im, Zeng-Chan Zhang, and Grant O. Cook, Jr. (LSTC)

  New inflator models for the automotive air bag are developed for the pyrotechnic and hybrid inflation modes. Several propellant examples including Sodium azide(NaN 3 ), Azodicarbonamide(C 2 H 4 N 4 O 2 ), and Guanidine nitrate(CH 6 N 4 O 3 ) are designed for users. To control the gas compositions into the airbag and the flame temperature in the combustion chamber, we modified an existing chemical equilibrium code, PEP(Cruise,1973) and provide a user-friendly code for users to develop their own propellant models. The inflating process is modeled by applying basic conservation laws to the several sub-sections of the inflator. Unlike existing inflator models, a new theoretical approach in a LS-DYNA model is provided. Advantages and disadvantages are discussed for the pyrotechnic and the hybrid models. In addition, we make available detailed descriptions of keyword files with comprehensive examples for the propellant ingredient control, cold and heat flow setup, and output file format options, which can be used to continue the air bag simulation with LS-DYNA’s ALE, SPH, and CESE airbag simulation capabilities.

• AIRBAG SIMULATION WITH LS-DYNA PAST – PRESENT – FUTURE

  A. Hirth - DaimlerChrysler AG, Germany, A. Haufe - Dynamore GmbH, Germany, L. Olovsson - IMPETUS Afea AB, Sweden

  During the last decade the simulation of the airbag deployment process has become a standard application of explicit finite element codes. At the beginning of the development the focus was to capture the influence and improve the results of dummy impact on fully inflated airbags. Later the deployment kinematics of folded airbags, different folding techniques and vent-hole design became more and more important. With the requirement to comply with FMVSS 208, i.e. Out-of-Position load cases, it became apparently necessary to include the interaction between the internal gas flow and the fabric airbag structure. Hence coupled algorithms that allow for interaction between the discretized gas flow and the airbag structure were the main focus during the past five years. The present paper aims to sketch the development history of airbag deployment simulations from the very beginning of the late 1980s to the current, highly sophisticated models available in LS-DYNA. Different modelling techniques will be shown and their advantages, drawbacks and the necessary effort to gain useful results will be discussed.

• AirbagApplication for Structural Racing Car Component

  Alessia Prato, Marco Anghileri, Andrea Milanese (Dipartimento di Scienze e Tecnologie Aerospaziali, Italy), Chiara Marozzi (CRM Group)

  In motorsports, there is a deep research in order to make cars more and more competitive, throughout an accurate study on aerodynamics, powerful and advanced engines, structural component design, materials and, of course, on racing strategy. That’s even more true when racing conditions are extremely severe, like in endurance races, such as 24 Hours of Le Mans, where changes in drivers and in racing conditions make the race more exciting. To improve performances, weight is one of the most strict design conditions: a lighter car is faster, more efficient and more competitive so that performances can be improved, with more controllability in acceleration and braking phases, reducing emissions and consumptions. Evolution in studies upon materials and structural applications has got a key role to reduce weight and the use of innovative structures is an open field for experimental tests. Many research works were performed upon materials used in motorsports, especially composite fiber reinforced ones. In [1], Adam presented a general overview on composite mechanical characteristics, production methods, and design principles for racing cars composite applications. In [2], a similar study was presented by Cole and Sherman referring to different light-metals and their use for automotive structural components. Innovative structural applications on car components were also studied in order to improve strength and reduce, at the same time, weight. In the fifties experimental tests carried out at Langley Aeronautical Laboratory of National Advisory Committee for Aeronautics (NACA) revealed that a small amount of pressure inside cylindrical components could increase strength. The first rigorous study upon this topic was performed by Lo, Crate and Schwartz [3]. From the comparison of experimental tests and analytical studies, they demonstrated that internal pressure can positively influence the resistance of cylindrical structures under torsional and compressive loads. Later some studies were carried out on specific cases, like silos and pipes, and Mathon and Limam [4] showed that the effects of internal pressure on closed cylinders under pure bending are dependent on the geometry and, particularly, on the ratio radius/thickness (R/t) and length/radius (L/R). Other studies [5] presented the effects on composite structures with different loads and with or without internal pressure. In this work, the effects of internal pressure on closed cylinders subjected to different loads were ® numerically investigated. Internal pressure was created throughout the use of LS-DYNA 971 airbag models and increasing levels of pressure were tested to evaluate the effect on the analyzed structure. Several FE models of different cylindrical geometries and loads were created and a comparison between metals and composite materials was numerically performed. A focused research on an innovative shape, that can take advantages from this kind of application, was also performed and its results compared with previous model ones.

• Aircraft Engine Blade-Out Dynamics

  Kelly S. Carney, Charles Lawrence, Dorothy V. Carney - NASA Glenn Research Center

  A primary problem in the design of aircraft gas turbine engine internal and support structures is the accurate simulation of the fan blade-out event and the subsequent windmilling of the engine. Reliable simulations of the blade-out event are required to ensure structural integrity during flight as well as to guarantee successful blade-out certification testing. A model and procedure has been developed which successfully predicts the key physical behavior of a generic engine structural dynamics. The key procedures and modeling techniques for this application are given.

• Aircraft NPP Impact Simulation Methodology

  Yu.V. Novozhilov (CADFEM CIS JSC), A.N. Dmitriev, D.S. Mikhaluk (CEPSA JSC), N.A Chernukha, L.Yu. Feoktistova ((ATOMPROECT JSC), I.A. Volkodav (SEC DDC JSC)

  The IAEA safety requirements imply that the design of nuclear power plants (NPP) considers both the potential technological disaster and acts of nature. One of the modern mandatory requirements of IAEA standard SRS 87 is to consider a possible massive commercial airplane crashing (APC) into or attacking NPP reinforced concrete (RC) structures. The basis for the methodology is well-validated RC structures modeling. LS-DYNA® constitutive models have been tested by solving a set of verification problems. Selected problems set describes different loading conditions and scales: single finite element study, quasi-static loading, low-speed impact, deformable missile impact, RC wall APC load, shock wave load, perforation by a kinetic missile. The following model parameters are examined: mesh convergence, contact algorithms work, immersed reinforcement coupling, nonlinear stability. The second part of the paper presents a universal method of APC events direct modeling based on the finite element method in the Euler formulation. The relations allowing to identify geometrical, strength, and mass parameters of the airplane finite element model by the given load curve and impact spot are developed. The model of the aircraft obtained in this way allows the transfer of loads on complex-shaped civil structures or when considering the impact at an angle to the surface, with great fidelity. The last part describes the simulation results processing and analysis procedure. Criteria for determining the strength based on the analysis of displacement, strain, and damage of both concrete and reinforcements are proposed. Approach to the evaluation of penetration, perforation, and fracture speed behind the barrier estimation is developed.

• Aircraft Seat Row-to-row Head Injury Criteria (HIC) Simulation Using LS-DYNA®

  E-June Chen, PhD, Boeing Commercial, Seattle, Washington

  Successful aircraft seat row-to-row HIC certification takes many test iterations and therefore is time intensive. Both developmental and certification tests are repeated to account for customized seat pitches, the range of occupant seated heights (from 5th percentile female to 95th percentile male), and several required impact zones. Row-to-row HIC prediction using simulation can help early design concept development (e.g., evaluating energy absorption devices and breakover mechanisms), and in turn reduce the cost of testing and the associated lead time. The objective of this paper is to introduce row-to-row HIC analysis and prediction using LS-DYNA. The seat modeling techniques for the row-to-row simulation were summarized. Two cases were used to demonstrate HIC predictability using simulation.

• Airdrop Sequence Simulation using LS-DYNA® ICFD Solver and FSI Coupling

  Morgan Le Garrec, Matthieu Seulin, Vincent Lapoujade, DynaS+, Toulouse, France

  In this framework, the payload freefall is considered for the present paper, from the airplane cargo bay up until the initiation of parachute deployment. The LS-DYNA simulations include multi-physics and fluid-structure interaction coupling. The currently developed ICFD solver is used in conjunction with the non-linear dynamic structural solver.

• ALE Adaptive Mesh Refinement in LS-DYNA

  N. Aquelet (LSTC)

  An adaptive mesh refinement capability was implemented in the 3D MMALE (Multi-Material Arbitrary Lagrange Euler) code. It automatically and locally refines (or coarsens) ALE hexahedral solid elements. The keyword *REFINE_ALE (or *ALE_REFINE) activating this feature has 3 lines of parameters that enable 3 different kinds of refinement. If the keyword has only one line, the refinement is static and only occurs during the initialization. If the second line is added, the refinement becomes dynamic. Adding the third line allows removing refined meshes.

• ALE and Fluid Structure Interaction in LS-DYNA

  M. Souli - Laboratoire de Mécanique de Lille, J. Wang, I. Do, C. Hao - Livermore Software Technology Corporation

  Fluid-structure interactions play an important role in many different types of real-world situations and industrial applications involving large structural deformation and material or geometric nonlinearities. Numerical problems due to element distortions limit the applicability of a Lagrangian description of motion when modeling large deformation processes. An alternative technique is the multi-material Eulerian formulation for which the material flows through a mesh, fixed in space and each element is allowed to contain a mixture of different materials. The method completely avoids element distortions. With an Eulerian-Lagrangian (fluid-structure) coupling algorithm, Eulerian parts may interact with Lagrangian parts in the same model. The Eulerian method is limited by dissipation and dispersion problems associated with the fluxing of mass across element boundaries. In addition, the Eulerian mesh must span the whole active space covering all Lagrangian structures and the spatial range of their motions. This requires a large mesh and thus high computing cost. The multi-material arbitrary Lagrangian-Eulerian (MMALE) method improves upon pure Eulerian formulation by allowing the reference fluid mesh(es) to translate, rotate and deform, thus minimize the amount of flux transport, and reduce mesh size of the reference fluid mesh(es).

• ALE AND FLUID-STRUCTURE INTERACTION IN LS-DYNA

  M’hamed Souli - Université des Sciences de Lille et Technologie

  A new Eulerian-Lagrangian coupling algorithm and improved multi-material ALE-capabilities have made LS- DYNA an efficient tool for analyzing large deformation processes, such as bird strike events and forging operations. This paper contains two example problems that illustrate the current features of the code.

• ALE and Fluid-Structure Interaction Capabilities in LS-DYNA

  M’hamed Souli - Universite des Sciences et Technologie de Lille, Lars Olovsson, Ian Do - Livermore Software Technology Corporation

  A new Eulerian-Lagrangian coupling algorithm and improved multi-material ALE-capabilities have made LS-DYNA an efficient tool for analyzing large deformation processes, such as bird strike events, forging operations and penetration problems. This paper contains four example problems that illustrate the current features of the code.

• ALE and Fluid-Structure Interaction Capabilities in LS-DYNA

  Lars Olovsson - Livermore Software Technology Corporation, M’hamed Souli - Universite d’Artois

  A new Eulerian-Lagrangian coupling algorithm and improved multi-material ALE- capabilities have made LS-DYNA an efficient tool for analyzing large deformation processes, such as bird strike events and forging operations. This paper contains two example problems that illustrate the current features of the code.

• ALE Formulation for the Evaluation of Seismic Behaviour of Anchored and Unanchored Tanks

  Z. Ozdemir - Bogazici University / Université de Lille, M. Souli - Université de Lille, Y. Fahjan - Gebze Institute of Technology

  Estimation of the potential degree of risk for tank failure during an earthquake is very difficult to quantify since the liquid-tank system possesses many different nonlinear behaviour mechanisms which may be triggered simultaneously or separately depending on the characteristics of earthquake, contained liquid properties, fluid depth, dimensions of the tank, roof type, material properties, supporting conditions and stiffness of underlying soil medium. These nonlinear behaviour mechanisms can emerge in the form of elephant foot and diamond shape buckling at the tank wall, rupture at the junction between tank wall and base, buckling at the top of tank and roof, settlement at tank support system and foundation and large amplitude deformations at the base plate. For the case of unanchored tank, in addition to these mechanisms, uplift of tank base, sliding of the tank and successive contact and separation between base plate and foundation can be observed when tank subjects to seismic loadings. The analysis tool used to quantify the tank behaviour has to take into account the effects of all aforementioned factors. Since LS-DYNA is capable of handling complexities associated with the nonlinear transient seismic response of unanchored tanks it is utilized in this study. ALE technique and contact algorithms of LS-DYNA are used to model the coupling of tank and fluid and the interaction between tank base and soil, respectively. The results are compared with the provisions given in tank seismic design codes used in the current practice.

• ALE Formulation for the Evaluation of Seismic Behaviour of Anchored and Unanchored Tanks

  Z. Ozdemir - Bogazici University / Université de Lille, M. Souli - Université de Lille, Y. Fahjan - Gebze Institute of Technology

  Estimation of the potential degree of risk for tank failure during an earthquake is very difficult to quantify since the liquid-tank system possesses many different nonlinear behaviour mechanisms which may be triggered simultaneously or separately depending on the characteristics of earthquake, contained liquid properties, fluid depth, dimensions of the tank, roof type, material properties, supporting conditions and stiffness of underlying soil medium. These nonlinear behaviour mechanisms can emerge in the form of elephant foot and diamond shape buckling at the tank wall, rupture at the junction between tank wall and base, buckling at the top of tank and roof, settlement at tank support system and foundation and large amplitude deformations at the base plate. For the case of unanchored tank, in addition to these mechanisms, uplift of tank base, sliding of the tank and successive contact and separation between base plate and foundation can be observed when tank subjects to seismic loadings. The analysis tool used to quantify the tank behaviour has to take into account the effects of all aforementioned factors. Since LS-DYNA is capable of handling complexities associated with the nonlinear transient seismic response of unanchored tanks it is utilized in this study. ALE technique and contact algorithms of LS-DYNA are used to model the coupling of tank and fluid and the interaction between tank base and soil, respectively. The results are compared with the provisions given in tank seismic design codes used in the current practice.

• ALE Incompressible Fluid in LS-DYNA

  Nicolas Aquelet - LSTC Livermore, Mhamed Souli - University of Lille

  The computation of fluid forces acting on a rigid or deformable structure constitutes a major problem in fluid- structure interaction. However, the majority of numerical tests consists in using two different codes to separately solve pressure of the fluid and structural displacements. In this paper, a monolithic with an ALE formulation approach is used to implicitly calculate the pressure of an incompressible fluid applied to the structure. The projection method proposed by Gresho is used to decouple the velocity and pressure

• ALE Incompressible Fluid in LS-DYNA

  Nicolas Aquelet, Mhamed Souli (LSTC)

  The computation of fluid forces acting on a rigid or deformable structure constitutes a major problem in fluid-structure interaction. However, the majority of numerical tests consists in using two different codes to separately solve pressure of the fluid and structural displacements. In this paper, a monolithic with an ALE formulation approach is used to implicitly calculate the pressure of an incompressible fluid applied to the structure. The projection method proposed by Gresho is used to decouple the velocity and pressure.

• ALE Incompressible Fluid in LS-DYNA

  N. Aquelet, M. Souli (LSTC)

  The computation of fluid forces acting on a rigid or deformable structure constitutes a major problem in fluid- structure interaction. However, the majority of numerical tests consists in using two different codes to separately solve pressure of the fluid and structural displacements. In this paper, a monolithic with an ALE formulation approach is used to implicitly calculate the pressure of an incompressible fluid applied to the structure. The projection method proposed by Gresho is used to decouple the velocity and pressure

• ALE Incompressible Fluid in LS-DYNA

  Mhamed Souli - University of Lille

  The computation of fluid forces acting on a rigid or deformable structure constitutes a major problem in fluid- structure interaction. However, the majority of numerical tests consists in using two different codes to separately solve pressure of the fluid and structural displacements. In this paper, a monolithic with an ALE formulation approach is used to implicitly calculate the pressure of an incompressible fluid applied to the structure. The projection method proposed by Gresho is used to decouple the velocity and pressure

• ALE Modeling of Explosive Detonation on or near Reinforced-Concrete Columns

  J. M. H. Puryear, D. J. Stevens, K. A. Marchand (Protection Engineering Consultants), E. B. Williamson (University of Texas), C. K. Crane (USACE Engineer Research and Dev. Center)

  The detonation of explosive threats in contact with or near reinforced concrete columns was modeled using the Arbitrary Langrangian-Eulerian (ALE) capability of LS-DYNA, in support of the development of a software tool for assessing the vulnerability of structures subjected to terrorist attack. The explosive, air, and concrete were modeled as fluids, and the reinforcement was modeled using beam elements. *MAT_72R3 was used for the concrete, and column damage was characterized using the scaled damage measure, an output from the constitutive model that quantifies damage to the material. The model was initially validated against a large database relating spall and breach thresholds of reinforced concrete slabs to charge weight and standoff. It was further validated against a small database for explosive loading against reinforced concrete columns. A parameter study was then performed to populate a results space comprising four column shapes over a representative ra nge of dimensions. This results space was used to develop a fast-running algorithm that will be implemented in the structural vulnerability assessment software.

• ALE Modeling of Surface Waves

  AQUELET Nicolas - Livermore Software Technology Corporation

  An Arbitrary Lagrange Euler formulation for the propagation of surface waves is developed in LS-DYNA®. The ALE computational time step in this code is divided in two cycles: a Lagrangian cycle in which the mesh follows the material deformation and an advection cycle in which the users through remapping algorithms control the mesh motion. The new feature presented in this paper is one of these remapping algorithms. It enables a Lagrangian behavior of free ALE mesh boundaries whereas, in the direction of the wave propagation, the ALE mesh is Eulerian to avoid distortions. Nodes on the ALE mesh borders moves with the surface waves during the Lagrangian cycle. During the advection cycle, the remap positions of these nodes are computed by interpolating the Lagrangian positions of their neighbors with biquadratic polynomials. If the wave amplitudes are too important, ALE smoothing can be used for the internal nodes and a specific smoothing is applied on the mesh surfaces.

• ALE/FSI AirBlast Modeling: On the Way to One Billion Elements

  The Arbitrarian Lagrangian Eulerian (ALE) method of LS-DYNA® software is the best actual solution to perform AirBlast simulation. Indeed, thanks to its coupling method (ALE/FSI), it allows to the user to model complex blast waves interaction with Lagrangian structures. Today, due to hardware advances (the computer power highly increased) and LS-DYNA technology enhancement (ALE Mapping, MPP), it becomes possible to consider models with a very large volume of air, while keeping a good accuracy with a small element size. These new possibilities lead to a quantity of elements never reached before, for which LS-DYNA and LS-PrePost® had to adapt. In this paper, based on work realized with the help of LSTC, we will explain what exactly are the issues of modeling an ALE/FSI model with more than 100 million elements and what solutions were found. We will present some facilities to pre-process such a big model, like the new LS-PrePost “Long Format” or an innovative way to create ALE mesh using a new LS-DYNA keyword. We will also discuss about other important points concerning MPP decomposition, memory needs and post- processing, in order to give LS-DYNA users a complete overview of the ins and outs.

• Alternative Models of the Offset and Side Impact Deformable Barriers

  Dr. Tore Tryland - Hydro Automotive Structures

  The deformable barriers consist mainly of honeycomb blocks with highly anisotropic behaviour. These parts are made from several layers with aluminium foil that is glued and stretched to form the honeycomb structure. Simple compression tests show high stiffness and strength when the cell structure is folded while both stiffness and strength are significantly lower when the deformation mode is mainly bending of the thin foil. Remember that the typical deformation mode involve also transverse displacement of barrier parts, and when the honeycomb structure is folded this may be seen as the interaction between local and global buckling. Therefore, shell elements are used to model the honeycomb structure, and alternative models of the offset and the side impact deformable barriers are made. Note that scaling is used extensively to limit the number of elements and thereby the computational time that is required. These models with about 30 000 shell elements seem able to predict the global response of the deformable barriers, and they may be easily refined to represent more local behaviour as well.

• ALUMINUM PLATE PERFORATION: A COMPARATIVE CASE STUDY USING LAGRANGE with EROSION, MULTI-MATERIAL ALE, and SMOOTH PARTICLE HYDRODYNAMICS

  Leonard E Schwer - Schwer Engineering & Consulting Services

  The focus of the present work is to perform an assessment of a relatively new class of numerical methods, referred to as meshfree methods, that offer analysts an alternate analytical technique for simulating this class of ballistic problems, without a priori trajectory knowledge, nor resorting to ad hoc criteria. The assessment is made by the comparison of projectile residual speeds provided by the various techniques, when used to simulate a ballistic impact experiment. The techniques compared are the meshfree method known as Smooth Particle Hydrodynamics, a Multi-Material Arbitrary Lagrange Eulerian (MM-ALE) technique, and Lagrangian with material erosion. Such comparisons inherently have aspects of an apples-to-oranges-to-pears comparison, but an effort has been made to minimize the numerous ancillary aspects of the different simulations and focus on the capability of the techniques. To minimize unintended differences in the simulations, the following three key aspects remain constant: 1. Only one software package (code) is used, 2. The same constitutive model is used, 3. The models were constructed by one analyst with a similar level of experience using the three modeling techniques. Even with these considerable constraints on the simulation comparisons, it is obvious that the results are subject to the analyst’s knowledge and skills in applying the various analysis techniques to the impact simulation. Thus the reader should not assess the merits of these techniques on the provided ‘answers,’ but should instead focus on the relative merits of each technique and their applicability to simulations of interest.

• ALUMINUM PLATE PERFORATION: A COMPARATIVE CASE STUDY USING LAGRANGE with EROSION, MULTI-MATERIAL ALE, and SMOOTH PARTICLE HYDRODYNAMICS

  Leonard E Schwer - Schwer Engineering & Consulting Services

  The focus of the present work is to perform an assessment of a relatively new class of numerical methods, referred to as meshfree methods, that offer analysts an alternate analytical technique for simulating this class of ballistic problems, without a priori trajectory knowledge, nor resorting to ad hoc criteria. The assessment is made by the comparison of projectile residual speeds provided by the various techniques, when used to simulate a ballistic impact experiment. The techniques compared are the meshfree method known as Smooth Particle Hydrodynamics, a Multi-Material Arbitrary Lagrange Eulerian (MM-ALE) technique, and Lagrangian with material erosion. Such comparisons inherently have aspects of an apples-to-oranges-to-pears comparison, but an effort has been made to minimize the numerous ancillary aspects of the different simulations and focus on the capability of the techniques. To minimize unintended differences in the simulations, the following three key aspects remain constant: 1. Only one software package (code) is used, 2. The same constitutive model is used, 3. The models were constructed by one analyst with a similar level of experience using the three modeling techniques. Even with these considerable constraints on the simulation comparisons, it is obvious that the results are subject to the analyst’s knowledge and skills in applying the various analysis techniques to the impact simulation. Thus the reader should not assess the merits of these techniques on the provided ‘answers,’ but should instead focus on the relative merits of each technique and their applicability to simulations of interest.

• An Adaptive Meshfree Galerkin Method for the Three-dimensional Thermo-mechanical Flow Simulation of Friction Stir Welding Process

  C.T. Wu, W. Hu (LSTC), H.P. Wang (GM Research and Development Center)

  In this paper, new numerical modeling of material flow in the thermo-mechanical friction stir welding process is presented. In this numerical model, the discretization in space is derived by the meshfree Galerkin method using a Lagrangian meshfree convex approximation. The discrete thermal and mechanical equations are weakly coupled as the time advances using a forward difference scheme. A mortar contact algorithm is employed to model the stirring effect and heat generation due to frictional contact. Heat conductance between contacting bodies is considered as a function of contact pressure. A two-way adaptive procedure is introduced to the coupled thermo-mechanical system to surpass potential numerical problems associated with the extensive material deformation and spatial discretization. In each adaptive phase, a consistent projection operation utilizing the first-order meshfree convex approximation is performed to remap the solution variables. Finally, a three-dimensional thermo-mechanical coupled friction stir welding problem is analyzed to demonstrate the effectiveness of the present formulation.

• An Adaptive Thick Shell Element for Crashworthiness Assessment of Laminated Composites

  Johannes Främby, Martin Fagerström (Chalmers University of Technology), Jesper Karlsson (DYNAmore Nordic AB)

  The automotive industry is strongly dependent on efficient numerical tools in order to assess the crashworthiness of laminated composites. Unfortunately, to achieve predictive assessments of fracture in laminated composites one must resort to computationally costly, high-fidelity layered models, which in practice makes full vehicle crash simulations very difficult (or even impossible). One solution to this is to use an adaptive modelling technique where an initially coarse model is automatically refined, when and where needed, during the analysis. In this context, we have developed an LS-DYNA® user element which can be adaptively refined through the thickness to allow for both so-called weak discontinuities (discontinuities in strain at material interfaces) and strong discontinuities (discontinuities in displacements, i.e. delamination cracks). Furthermore, we have proposed a remedy to the numerical instabilities which arise from using adaptive refinement in a dynamic explicit solver. This adaptive element proves capable of reproducing the result of high-fidelity models, although at a lower computational cost.

• An Advanced Identification Procedure for Material Model Parameters based on Image Analysis

  L. Peroni, M. Scapin, C. Fichera (Politecnico di Torino)

  Inverse methods for the material strength model calibration are widespread techniques, which allow taking into account for the actual strain, strain-rate, temperature and triaxiality fields inside the specimen. An optimization procedure generally starts from experimental measurement of force-stroke time history and is based on the minimization of the difference between experimental and numerically computed quantities. In this work, the strength model identification is performed also on the basis of the specimen shape recorded during the test. This information is imposed as boundary condition, which forces the experimental profile to the external surface of the specimen.

• An airbag application for the ALAR incidences for the Passenger Aircrafts

  Vailore Anandan

  The airbag system can be designed to reduce the damage on the fuselage during an Approach and Landing Accident Reduction (ALAR) situations as well as ditching in the water for the transcontinental flights. Minimum hull damage protects the passengers in deep waters. A preliminary investigation for this end is performed in this paper. A simple model under 10000 elements is used to investigate the problem. The findings of the LS-DYNA finite element simulation are reported in this paper. It also shows a filtering effect on the impact pulse on the structure. The spikes on the deceleration pulse can create injury to the occupants. The airbag filters the pulse thus reducing various injuries to the occupant apart from hull protection. The most useful feature is its automatic deployment at the most critical moment. This is also useful for the small and mid-size aircrafts to survive various ALAR incidences. It saves life as well as property in case of the small crafts.

• An Analysis of the Hot-forming Process with Thermal and ICFD Simulations

  M. Kintsch, S. Szabo, R. Schneider (Voestalpine Automotive Components)

• An Application of LS-DYNA for the New FMVSS 208 Front Impact Tests

  Charlotte Jamte, Tim Keer, Richard Maloney, Joshua Weage - Arup

  The automotive safety community is currently facing the challenge of new front impact legislation (FMVSS 208), to be introduced in the USA in 2004. Vehicles will be subjected to an increased number of and type of barrier tests. This paper describes a new technique, using LS-DYNA, to aid the vehicle development process. A virtual “sled” has been developed for analysis of the different FMVSS 208 impact scenarios. This sled model would typically be created and exercised early in the vehicle development process, before a full vehicle model can be created. The sled can incorporate the target structural response of the occupant compartment (translational and rotational accelerations; intrusion; yaw and pitch; steering column motion), the restraint systems (airbags and seat-belts) and the occupants (driver and passenger; different percentile dummies). This modular approach allows different barrier configurations (rigid; rigid angled; deformable offset), impact speeds and occupant sizes (Hybrid III 5th and 50th) to be modeled with simple changes to the input file. The benefits of this approach are the ability to obtain a preliminary assessment of vehicle compliance for a wide range of impact scenarios at a time when the vehicle package is still being determined.

• An Application of Shape Similarity Recognition Using PCA based Dimensional Compression

  Masahiro Okamura

  In recent years, the demand for faster product development has been increasing year after year. In addition, as requirements and their levels become more sophisticated, data-driven development that makes use of past data is attracting attention. Compared to experiments, simulations are characterized by the ease of retaining data that can be used for analysis, but this creates the problem of handling huge amounts of result data. In order to overcome this challenge, we propose a method to detect similar behaviors based on the distance in the modal space obtained from the animation results of past calculations with a reduced dimension reduction technique.

• An Approach for Modeling Shock Propagation Through a Bolted Joint Structure

  Pouya Shojaei, Mohamed Trabia, Brendan O'Toole, Jed Higdon (University of Nevada, Las Vegas)

  Impact loading is typically characterized by a relatively large load happening over an extremely short duration and inducing broad range of vibration frequencies. Standard design approaches of bolted joints based on static or quasi-static criteria may not be effective under these conditions. This study focused on simulating a drop-weight tower experiment where a free-falling mass impacted a target plate, which was bolted to a cylindrical structure. An accelerometer was used to record transmitted acceleration to the cylindrical structure. An approach for simulating the shock propagation was proposed using LS-DYNA® Explicit finite element code. To reduce computational time, thread was not included. Instead, bolts were represented as cylinders with cross-sectional areas equal to the tensile stress area of the bolts. The results showed good agreement between the finite element and experimental results.

• An Approach to capture the Ejection Mitigation Requirements of FMVSS 226 with Finite Element Simulations

  André Haufe, George Dimitru - DYNAmore GmbH, Andreas Hirth - Daimler AG, Robert Kirchner - Friedmann & Kirchner

• An Assessment of ALE Mapping Technique for Buried Charge Simulations

  I. Kurtoğlu (FNSS Savunma Sistemleri)

  In this work, the effects of ALE mapping technique developed by LSTC [1] are investigated for buried charge simulations. Before mapping studies, a mesh sensitivity study is performed for the pure ALE simulations to investigate the effect of 3D mesh size on the impulse. The ALE mapping is performed from a 2D axisymmetric model to full 3D model.

• An Assessment of the LS-DYNA Hourglass Formulations via the 3D Patch Test

  Leonard E. Schwer - Schwer Engineering and Consulting Services, Samuel W. Key - FMA Development, LLC, Thomas A. Pučik - Pučik Consulting Services, Lee P. Bindeman - Livermore Software Technology Corporation

  The six hourglass formulations available in LS-DYNA for 8 node hexahedral elements are evaluated using the so called ‘3D Patch Test.’. It is demonstrated that three of the six hourglass formulations fail this patch test, including the popular default LS-DYNA viscous form of hourglass control. A detailed description of the 3D Patch Test is provided to allow readers to perform the simple test as part of their code verification.

• An assessment of the new LS-DYNA layered solid element: basics, patch simulation and its potential for thick composite structure analysis

  Madhukar Chatiri - CADFEM GmbH, Thomas Güll - Adam Opel GmbH, Prof. Anton Matzenmiller - University of Kassel

  One major component of fuel cell vehicles is the hydrogen storage system. A promising and nowadays mostly used approach is to store hydrogen in wet wound carbon fiber reinforced plastic (CFRP) vessels manufactured by filament winding process with an operating pressure of up to 70 MPa (hereafter referred as H2 vessel). Due to the inherent complexity and 3-dimensional nature, accurate behavior of such thick composite structures in impact simulations needs an adequate representation of the composite plies. Modeling thick composite structures with 2-dimensional elements will produce inaccurate results in transverse normal direction. Thus 3D modeling should be used but to model each ply with one solid element leads to undesirably big models and is impractical for large structures. Thus representation of several plies in one solid element and more such elements across thickness is desired. Also, solid elements are needed to represent the 3-dimensional state of stress and impact direction normal to the outer vessel surface. A new layered solid element formulation is implemented in LS-DYNA® Version 971 R4 allowing the definition of multiple integration points through the thickness in combination with arbitrary material orientation. The above new element formulation is presented in this paper describing different patch simulation results and simulation results for thick composite structures such as hydrogen storage H2 vessels.

• An assessment of the new LS-DYNA layered solid element: basics, patch simulation and its potential for thick composite structure analysis

  Madhukar Chatiri - CADFEM GmbH, Thomas Güll - Adam Opel GmbH, Prof. Anton Matzenmiller - University of Kassel

  One major component of fuel cell vehicles is the hydrogen storage system. A promising and nowadays mostly used approach is to store hydrogen in wet wound carbon fiber reinforced plastic (CFRP) vessels manufactured by filament winding process with an operating pressure of up to 70 MPa (hereafter referred as H2 vessel). Due to the inherent complexity and 3-dimensional nature, accurate behavior of such thick composite structures in impact simulations needs an adequate representation of the composite plies. Modeling thick composite structures with 2-dimensional elements will produce inaccurate results in transverse normal direction. Thus 3D modeling should be used but to model each ply with one solid element leads to undesirably big models and is impractical for large structures. Thus representation of several plies in one solid element and more such elements across thickness is desired. Also, solid elements are needed to represent the 3-dimensional state of stress and impact direction normal to the outer vessel surface. A new layered solid element formulation is implemented in LS-DYNA® Version 971 R4 allowing the definition of multiple integration points through the thickness in combination with arbitrary material orientation. The above new element formulation is presented in this paper describing different patch simulation results and simulation results for thick composite structures such as hydrogen storage H2 vessels.

• An Assessment of the New LS-DYNA® Multi-Layered Solid Element: Basics, Patch Simulation and its Potential for Thick Composite Structural Analysis

  Thorsten Schütz - Adam Opel GmbH, Anton Matzenmiller - Univ. of Kassel, Madhukar Chatiri - CADFEM GmbH

  Limitation of fossil fuels and global warming favor the introduction of new powertrain concepts for road vehicles with highest efficiency and low greenhouse gas emissions. Fuel cell vehicles offer the highest potential for sustainable mobility in the future. One major component of fuel cell vehicles is the hydrogen storage system. A promising and currently the most-used approach is to store hydrogen in wet-wound carbon fiber reinforced plastic (CFRP) vessels manufactured by a filament winding process with an operating pressure of up to 70 MPa (hereafter referred as H2 vessel). Due to the inherent complexity and the 3-dimensional nature, accurate behavior of such thick composite structures in impact simulations needs an adequate representation of the composite plies. Modeling thick composite structures with two-dimensional elements will produce inaccurate results in transverse normal direction. Therefore, 3D modeling should be used but the idealization of each ply with one solid element leads to undesirably large models and is impractical for large structures. Hence, representation of several plies in one solid element and more such elements across the thickness is aspired. An improved multi-layered solid element showing excellent efficiency of CPU time is implemented in the code of LS-DYNA® Version 971 R4. Like any brick element, it resolves the 3D stress state necessary for impact directions normal to the outer vessel surface. The element allows the definition of multiple integration points through the thickness in order to account for stacks of plies with arbitrary fiber orientation. By defining several layers with different material properties and ply orientations inside one multi-layered solid, the number of elements through the thickness is remarkably reduced and still, the result is close to the one obtained from the detailed finite element model of one brick element per layer. As depicted in Fig.1.2, a complex laminate configuration consisting of 18 different plies with varied fiber angles is represented by one multi-layered solid element with 18 integration points through the thickness. The above new element formulation is presented in this paper describing simulation results for both, different patches and for thick composite structures such as for hydrogen storage H2 vessels.

• An Assessment of the Robustness of the European Pedestrian Leg Impact Test Using LS-OPT and LS-DYNA

  Tim Keer - Arup

  The automotive safety community is currently facing the challenge of new pedestrian impact requirements, introduced in Europe in 2005. These requirements necessitate considerable changes to the vehicle front end (bumper system, hood and fenders). LS-DYNA models of the pedestrian impactors (head, upper leg and leg) are an important tool for analysis of the various tests that comprise the new requirements. One of the criticisms of the current tests concerns repeatability. Physical testing with the leg impactor, in particular, shows considerable scatter of results. This lack of repeatability can cause the system to be over-designed to give sufficient confidence that the vehicle will meet the pedestrian safety requirements during compliance testing. Lack of repeatability in the results from physical leg impact tests can be caused by three main groups of factors: - variations in the vehicle (e.g. build tolerances) - variations in the legform impactor (e.g. properties of the Confor foam “skin”) - variations in the test set-up (e.g. impact velocity) This paper describes an LS-OPT study designed to assess these issues. An LS-OPT Monte Carlo simulation was used to perform a series of LS-DYNA analyses and to assess the relative importance of the different factors in these groups. The results give insight into the parameters which should be controlled most tightly in order to improve the repeatability of leg impact testing. The paper concludes with a discussion of the benefits of this approach and the potential for further application.

• An automated belt fitting tool for 6 and 10 year-old child crash dummies

  Gillian Mara, Christian Dalton (Semcon)

  Modelling child occupant safety through computer aided engineering (CAE) within a vehicle is an area that is constantly developing. In 2003, Euro NCAP introduced a child occupant protection rating to inform consumers the results of vehicle safety assessments [1]. These assessments used 18 month and 3 year old dummies in frontal and side crash. Developments in technology and crash dummies have led to the introduction of new larger child dummies in the Q series, those being the 6 and 10 year old. In 2016-18 it is proposed these will be used in frontal and side EuroNCAP consumer crash ratings, where the dummy will be sat in a child seat. In the competitive market there is a demand on manufacturers to produce cars in a shorter time frame from idea to production, therefore making the overall process more efficient and cost effective. One area that this places emphasis on is predicting how cars perform where it has the potential to reduce the need to produce as many prototype vehicles. To ensure the results are accurate the predictive method of finite element analysis (FEA) is very dependent on the inputs, where those are primarily grouped into materials, geometry and boundary conditions. In terms of the child occupant prediction this means obtaining realistic inputs to gain realistic output kinematics and injury criteria during the frontal or side crash. The belt restraint system is one of the most predominant in affecting the child kinematics and one that needs to be modelled accurately. This paper will describe an automated seat belt fitting method using the LS- DYNA® package that is efficient and effective in creating a belt geometry and path for a 6 and 10 year old dummy in a child seat.

• An Automated Process for Interior Head Impact Analysis

  Thanassis Fokilidis, Antonis Perifanis (BETA CAE Systems SA), Anneli Hoegberg (VOLVO CAR Corporation)

  During the last decade, the Occupant Protection legislation requirements on interior safety properties of automobiles have become considerably more demanding. The US standard laboratory test procedure FMVSS201U regulates the tests for the head protection against the event of its impact on the upper interior roof. The procedure involves the identification of the most critical target zones and headform target angles. To minimize the need for physical tests, the product performance evaluations are, as far as possible, performed with numerical simulations involving CAE software. However, covering all possible load cases would require an infinite number of simulations. In order to automate the generation of input data and to assist in finding the critical load parameters, Volvo Cars Safety Centre and BETA CAE Systems employed a process that involves ANSA pre- SURFHVVRU DQG (7$ SRVW-processor, extended with special tools. This automated process starts with the model file input to ANSA and concludes with the assessment of the LS-'<1$ UHVXOWV ZLWKLQ ü ù requiring minimum human interaction. An advanced algorithm, for the automatic headform positioning, which identifies the areas where the maximum vertical angle can be reached, has been developed. The process also involves a robustness analysis for each target point, and thus reduces the uncertainty of the problem. This has been successfully deployed within Volvo Cars Safety Centre, leading to great reduction of modelling time

• An Effective Curve Matching Metric for Parameter Identification using Partial Mapping

  Katharina Witowski - DYNAmore GmbH, Markus Feucht - Daimler AG, Nielen Stander - Livermore Software Technology Corporation

  This paper describes a new method for curve matching essential to the solution of inverse problems represented by system parameter identification. Hysteretic response curves are specifically addressed as a general class. The method is based on Partial Curve Mapping (PCM) of the experiment curve onto the computed curve. This methodology involves a curve matching metric which is computed using the volume between the test curve and the computed curve section. A number of examples are presented to demonstrate the capability. These examples represent hysteretic curves which are impossible to match without mapping.

• An Efficient Modeling Procedure for Simulation of Dynamics of Adhesively Bonded Joints

  Anindya Deb, Indrajit Malvade (CPDM, Indian Institute of Science)

  The present study is aimed at developing a new computationally efficient modeling procedure that predicts well the nonlinear mechanical behavior of adhesively bonded joints. The approach is thought to be particularly beneficial for computationally intensive vehicle crash simulations. Two other conventional modeling approaches are considered, that is, accounting for adhesive layer between shell-based substrates/flanges with monolithic solid elements, and defining a tied contact with failure condition in lieu of the solid elements. The approach presented here and not previously reported in the literature is an enhancement of the latter technique with equivalent properties being assigned to the substrates in the overlap segment of a joint model. A semi-analytical procedure is outlined in detail for arriving at the equivalent properties of substrates by accounting for shear properties of an epoxy adhesive which is geometrically not represented in the model. It is shown that the effect of strain rate on adhesive behavior can be elegantly incorporated in the proposed equivalent property-based approach via Material Type 24 in LS-DYNA for intended applications of dynamics such as vehicle crash safety assessment. The computational efficiency and accuracy of the present approach are established by comparing results yielded by it against experimental data and detailed shell-solid modeling technique.

• An Efficient New Sequential Strategy for Multi-Objective Optimization using LS-OPT

  N. Stander (LSTC)

  ®A new surrogate-assisted Multi-Objective Optimization algorithm has been implemented in LS-OPT . The algorithm, known as Pareto Domain Reduction, is an adaptive sampling method and an extension of the classical Domain Reduction approach (also known as SRSM). A Multidisciplinary Design Optimization (MDO) example involving a vehicle impact is used to demonstrate that the accuracy is very close to the NSGA-II “exact” method while using a small fraction of the computational effort.

• An Efficient Shell Element Based Approach to Modeling the Impact Response of Fabrics

  Ali Shahkarami, Reza Vaziri - The University of British Columbia, Canada

  An efficient shell element based computational model is developed to capture the mechanical response of fabrics. The approach considers a single yarn crossover as the basic building block (unit-cell) of the fabric panel and uses a specially formulated shell element within LS-DYNA to capture the essential features of the membrane response of this unit-cell accounting for both geometrical and material characteristics of the yarns. The shell element so developed is used to simulate the impact response of single and multi-ply packs of Kevlar® 129 fabric. The predictions are successfully compared with the measurements obtained from instrumented ballistic impact experiments.

• An Engineering Approach of an X-Ray Car Crash Under Reverse Small Overlap Configuration

  Y. Leost, P. Bösl, I. Butz, T. Soot, M. Kurfiß, S. Moser (Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI), A. Nakata, F. Kase, T. Hashimoto, S. Shibata (Honda R&D Co., Ltd.)

  During a crash event, conventional optical measuring systems provide information about the deformation of parts that are directly visible. The new measuring method called X-Ray Car Crash (XCC) developed at Fraunhofer EMI allows accessing the crash kinematic of specific parts inside the vehicle. This method provides precious information that is currently not accessible in a crash test and allows for better comparison with FEM simulations. The present paper describes a preliminary study performed in collaboration with Honda R&D Co., Ltd. The load case under consideration is a reverse variant of the IIHS Small Overlap with integrated X-Ray technology. Fraunhofer EMI Research Crash Center aims at developing new measurement methods to investigate non-standard high-speed dynamics safety issues. Most of these specific requests are coming from car manufacturers. In order to achieve maximum test reproducibility and simplify boundary conditions, the facility is equipped with a propelled sled system on rails. Thus, it enables to perform impactor to vehicle scenarios with moving barriers up to 3000 kg by 22 m/s. The standard Small Overlap at 64 km/h belongs to the vehicle to barrier scenario and requires some preliminary computations to adapt it for the EMI Crash test facility. Special consideration was given to energy balance in order to determine the right barrier velocity and mass to achieve a similar intrusion in the car to in the standard configuration. Numerical simulations were required at each step to meet the different challenges of this study. This paper describes first the numerical assessment of the validity of the reverse scenario. FEM simulations were then used extensively for developing a special moving barrier presenting maximal structural robustness, well-balanced dynamic behavior and allowing on-sled measurement technics and braking system. Then, LS-DYNA® simulations provided necessary data to perform ray tracing simulations and thus finding the right placement for X-ray source and X-ray detector. Finally, numerical simulations played an important role for an enhanced test setup, by finding the best balance between appropriate mechanical robustness of supporting structures (so called Pit-cover) and low X-ray attenuation.

• An Engineering Approach to Estimating Partially Saturated Soil Constitutive Properties Using LS-DYNA®

  Len Schwer, Schwer Engineering & Consulting Services, 6122 Aaron Court, Windsor, California, 95492;, Matt Barsotti, Protection Engineering Consulting, 14144 Trautwein Road Austin, Texas 78737

  Soil is perhaps the most common civil engineering material, and ironically one of the most difficult to model due to its variability. At any given site, soil samples taken at different depths and distances may show considerable variability. Even if such samples show relative uniformity, there is often the question of what happens if it rains and the soil saturation changes?

• An Enhanced Assumed Strain (EAS) Solid Element for Nonlinear Implicit Analyses

  Fredrik Bengzon, Thomas Borrvall, DYNAmore Nordic AB;, Ushnish Basu, Livermore Software Technology Corporation (LSTC)

  Historically, the importance of computational efficiency in explicit analysis has driven the element development in LS-DYNA® [1,2] towards fast and sufficiently accurate formulations. Single point integrated elements with stabilization are well established techniques in this area. The recent growth of implicit analysis has led to a demand of increased accuracy of the element response, and consequently more sophisticated formulations have been introduced in recent years. While high order elements provide a better response, low order elements remain popular due to their simplicity and robustness. An area that has not yet been exploited in LS-DYNA is the family of enhanced assumed strain (EAS) elements, the reason being the computational cost associated with this approach. Solid element 18 is a linear Wilson element based on this technology, but is only available for linear implicit analysis. The goal with this paper is to generalize this to fully nonlinear implicit analysis, and provide information on its merits and drawbacks.

• An Enhanced Bond Model for Discrete Element Method for Heterogeneous Materials

  Zhidong Han, Hailong Teng and Jason Wang (LSTC)

  The enhanced bond model allows the Discrete Element Method (DEM) to simulate the heterogeneity and discontinuity at the individual particle level at the micro level. The traditional material models at the macro level are applied to each particle independently. This bond model bridges the behaviors of particles at macro and micro levels, and may be used for failure analysis of the homogeneous & heterogeneous materials, including composites, concretes.

• An enhanced Design exploration using Modal decomposition of Key events in Frontal crash simulation

  M. Okamura, H. Oda (JSOL)

  In recent years, CAE has been used extensively in vehicle development, and parameter study of sheet metal thickness for design exploration and optimization is one of the major applications. Response surface method is commonly used for this application among various analysis tools. The concept is to connect input variables such as sheet metal thickness and output variables such as firewall intrusion with non-linear functions such as radial base, kriging, and neural network.

• An Enhancement of LS-DYNA® XFEM Shells for Dynamic Ductile Failure Analysis

  Y. Guo, C. T. Wu, W. Hu, Livermore Software Technology Corporation (LSTC), Livermore, CA 94551, USA;, K. Takada, H. Okada, utomobile R&D Center, Honda R&D Co., Ltd, Tochigi, 321-3393 Japan;, N. Ma, Center of Computational Welding Science (CCWS), Osaka University, Osaka, 567-0047 Japan;, K. Saito, Engineering Technology Division, JSOL Corporation, Tokyo, 104-0053, Japan

  This paper presents an enhancement of LS-DYNA XFEM shell method [30] for dynamic ductile failure in shell structures. The XFEM shell formulation adopts the finite element continuous-discontinuous approach. The continuum damage model based on continuous displacements is used in the continuous stage to describe the diffuse micro-cracking in ductile failure before a macro-crack is formed. In the context of first-order shear deformable shell finite element method, a nonlocal modelling procedure based on a projection of mid-plane reference surface is introduced to regularize the element-wise strain fields induced by the continuum damage model. In the discontinuous stage, an incorporation of velocity discontinuities in shell finite elements is pursued by XFEM method when the damage variable exceeds a critical value and the transition from a continuous to a discontinuous model is permitted. A phantom-node approach [17] is employed in XFEM method to simplify the numerical treatment of velocity discontinuities in the shell finite element formulation. Several numerical benchmarks are examined using the explicit dynamics analysis and the results are compared with the experimental data to demonstrate the effectiveness and accuracy of the numerical method.

• An Eulerian Finite Element Model of the Metal Cutting Process

  A. Raczy, W. J. Altenhof, A. T. Alpas - University of Windsor

  The Eulerian element formulation was employed in the modeling of the orthogonal metal cutting process of commercial purity copper. The constitutive material models elastic-plastic hydrodynamic and Johnson-Cook, were utilized in modeling the workpiece behavior. The capabilities of each model to replicate the experimental chip geometry, stress and strain distributions, and cutting forces, were investigated. The numerical strain distributions, were in good agreement with the experimental strain distribution. The maximum strains of ε p = 8.3 and ε p = 5.6 for the Johnson-Cook material and hydrodynamic material, respectively, occurred in the tool tip region, and were in good correlation with the experimental strain of ε p = 8.1 at this location. The experimental and numerical distributions, all predicted strains of approximately ε p = 3.5 to 3.6 beneath the machined surface and adjacent to the rake face. The stress distributions in both of the investigated materials were noticeable different. The Johnson-Cook model showed a stress increase of up to 425 MPa in the primary deformation zone, while the hydrodynamic model predicted increased stresses of 380 MPa in the secondary deformation zone. The hydrodynamic stress distribution was more consistent with experimental findings, which similarly showed a stress increase, up to 360 MPa, in the secondary deformation zone. The maximum stress in the hydrodynamic material (410 MPa) and in the Johnson-Cook material (438 MPa) were located at the tool tip, and showed good correlation to the maximum experimental stress of 422 MPa, also occurring at the tool tip. The sizes of both the primary deformation zone (350 μm), and the secondary deformation zone (50 μm) predicted by the hydrodynamic and Johnson-Cook material models were in agreement with the experimental observations. The steady state cutting force prediction of the hydrodynamic material was 1332 N, and was within 13% of the experimental findings. The numerical–experimental correlations indicate the Eulerian finite element approach is an effective way of modeling the metal cutting process.

• An Evaluation of Active Knee Bolsters

  Zane Z. Yang - Delphi Corporation

  In the present paper, the impact between an active knee bolster system and occupant knees has been studied using finite element analysis. The active knee bolster system consisted of an inflatable molding part and a pair of EA supporting brackets. Also included in the FEA model was the entire vehicle cockpit. Both driver-side and passenger- side occupants were considered. The active knee bolster FEA model was first validated by test data including kinematics and femur loads. The performance of active knee bolsters was then compared with that of conventional structural knee bolsters

• An Experimental and Numerical Investigation on Vulcanized Fiber

  K. Bayram, M. Pfeiffer, C. Alter, Prof. S. Kolling (THM)

  As the automotive industry and its companies start to look for sustainability, materials made of natural fibers receive a growing interest. In the present work, the mechanical properties of a vulcanized fiber material were investigated to understand the orthotropic and rate-dependent material behavior and make it more predictable and thus practicable. *MAT_PAPER was used to represent the anisotropic elastic-plastic behavior of the material for crash and impact simulations. To confirm numerical results from explicit FEM calculations, a user material subroutine comparable to *MAT_PAPER was utilized. Therefore, it was possible to perform implicit calculations of the conducted validation experiments which were performed at low strain rates.

• AN EXPERIMENTAL AND NUMERICAL STUDY ON THE ENERGY ABSORBING CAPABILITY OF ALUMINUM EXTRUSIONS UNDER OBLIQUE LOADING

  A. Reyes, M. Langseth, O. S. Hopperstad - Structural Impact Laboratory

  Oblique loading was studied through static experiments and numerical simulations. The behavior of square aluminum columns in alloy AA6060 subjected to oblique loading was investigated experimentally for three different load angles. The square columns were clamped at one end and oblique load conditions were realized by applying a force with different angles to the centerline of the column. Numerical simulations were later carried out to validate the numerical model.

• An Implicit Incompressible CFD Solver in LS-DYNA for Fluid-Structure Interaction Problems

  Facundo Del Pin - Livermore Software Technology Corporation

  The present work is an introduction to a new CFD solver in LS-DYNA®. This solver is part of the efforts put in LS- DYNA with the objective to expand the capabilities into new challenging problems in industry. The new CFD solver will focus on fluid-structure interaction (FSI) applications where incompressible fluids interact with the existing structures in LS-DYNA. Incompressible flows are present in a great variety of industrial applications from sloshing problems to aerodynamics at low Mach numbers. This new incompressible CFD solver coupled to LS-DYNA mechanics will provide an implicit time integration scheme allowing larger time steps and faster convergence to steady state. One of the main features of the solver is the Lagrangian representations of all FSI interfaces providing exact imposition of boundary conditions. In this way the fluid mesh and the solid mesh are tightly coupled such that the fluid domain deforms following the Lagrangian structure displacements. The rest of the domain follows an Arbitrary Lagrangian-Eulerian formulation. The image bellow shows the mesh movement and the conformity of the fluid mesh to the solid mesh.

• An Implicit Study of High Order Elements in LS-DYNA

  T. Borrvall (DYNAmore Nordic); Prof. D. Benson, H. Teng (LSTC)

  An overall trend in simulation technology is towards increasing the accuracy of model features to yield a more rapid convergence with mesh refinement. In the context of element technology, migrating from shells to solids or from low to high order elements are possible ways to accomplish this. High order elements are therefore of particular importance in implicit analysis, where spatial discretization is limited by algorithmic complexity and memory consumption. Sometimes simulation standards and company regulations even make quadratic elements mandatory, and by tradition they are an important contribution to an implicit finite element software. LS-DYNA is a strong player on the implicit market and today offers a complete set of quadratic shell and solid elements. The intent with the present paper is to give an overview of the implicit capabilities of these elements, including reports on accuracy and convergence, in fairly standard simulation examples. Below some implicit deep drawing examples using high order shells (left) and solids (right) are shown.

• An Improved 3D Adaptive EFG Method for Forging and Extrusion Analysis with Thermal Coupling in LS-DYNA

  Hongshneg Lu - Shanghai Hengstar Technology Co. Ltd., C. T. Wu - Livermore Software Technology Corporation

  The 3D adaptive EFG method using conventional moving least-square approximation or fast transformation method [1] has been successfully applied to metal forging and extrusion analysis thanks to its high accuracy in dealing with large material deformation [2] in LS-DYNA. Recently, a meshfree convex approximation [3-5] was developed to be an alternative in the large deformation analysis. However, its application to the adaptive method has not been investigated. In this paper, an improved version of 3D adaptive EFG method with emphasizing on the modified maximum entropy approximation, whose approximation is non-negative and owns Korncker-Delta propriety at the boundary, is presented. The thermal effect in forging and extrusion problem is considered, and a scheme to interpolate the thermal state variables during the adaptive procedure is proposed.

• An Integrated Modeling Scheme for Sensor Embedded Woven Composite Structures in Manufacturing Simulation

  T. Usta, C. Liebold (DYNAmore), M. Vinot (DLR)

  This work focuses on an integrated modeling scheme of a sensor embedded woven composite structure which is created for the joint project “Digitaler Fingerabdruck” (DFA) or in English: “Digital Fingerprint” within the research campus ARENA2036 [4]. The process chain includes a draping simulation of a woven fabric and a trimming simulation using LS-DYNA®, optimization of a tailored-fiber placement process on top of this woven fabric structure using Optistruct®, fiber direction mapping from weaving simulation results using beam elements to shell element target meshes and handling of reinforcing patches using the mapping tool Envyo® [5]. The final goal is to establish an integrated process chain with parametrized variables using LS-OPT® for robustness analysis. A new feature of *MAT_REINFORCED_THERMOPLASTIC (*MAT_249) is also demonstrated to introduce fiber directions as an integration point history variable in global coordinate system to the subsequent simulations [7].

• An Integrated Process for Occupant Safety Simulations with LS-DYNA & MADYMO Coupling

  Cédric Canadas, Tom Van Langenhove, Christophe Liefooghe - LMS International, Paul van Catz, Peter Ritmeijer - TASS

  This paper presents an innovative integrated process to perform occupant safety simulation with LS-Dyna & Madymo coupling. More than ever before, the automotive industry operates in a highly competitive environment. Manufacturers must deal with competitive pressure and with conflicting demands from customers and regulatory bodies regarding the vehicle functional performance, which forces them to develop products of increasing quality in even shorter time. To address these challenges and deliver optimal collaboration between design and engineering, the integration between CAD and CAE is key. Through a strong link between CAD and CAE, along with the integration of all simulation steps in one environment, new methodologies are developed, allowing the full utilization of parametric geometry based analysis, enabling quick “what if” scenarios simulation, and thus front-loading design with simulation. Complex CAD based assembly is fully automated, reducing the risk of modeling mistakes. Moreover, repetitive tasks such as definition of the model symmetry, are performed automatically. These functionalities allow crash engineers to focus on the impact/safety simulations set up and not on the model construction. LMS Virtual.Lab is fully integrated with Dassault System CATIA V5, therefore seamlessly linking CAD with CAE. In the field of occupant safety, Virtual.Lab pushes the integration a step forward through the support of Madymo Coupling Assistant. Tedious dummy positioning and coupling contact creation becomes straightforward with the visualization of the Madymo dummy in its LS-Dyna FE model environment. A real life industrial case is presented consisting of a CAD based assembly of a door sub-system is performed automatically through automation, and then integrated within a quarter body in white. A Madymo dummy is then positioned wrt the vehicle model, allowing to define coupling simulation of a side impact with LS-DYNA and MADYMO solvers. Back to back comparison of traditional CAE and the proposed new methodology is highlighted to provide a measure of the savings that can be realized.

• An Interprocess Communication based Integration of AI User Materials into LS-DYNA

  Joachim Sprave, Tobias Erhart, Andr´e Haufe

  Machine Learning (ML) driven material models have been investigated for some time now. The respective ML models can be trained outside of the Finite Element solvers by means of given strain paths and corresponding stress results which have either been recorded from simulations, drawn from distributions, or even measured from hardware tests. The trained models can be easily evaluated regarding their performance based on an-other set of strain paths with results that have not been presented to the model during training. When a model has reached a promising prediction accuracy on the validation data, the natural next step is to test it in a finite element simulation by integrating the trained model as a user material.

• An Introduction to the LS-DYNA® Smoothed Particle Galerkin Method for Severe Deformation and Failure Analyses in Solids

  C. T. Wu, Y. Guo, W. Hu (LSTC)

  This paper presents a new particle method in LS-DYNA for the severe deformation and failure analyses of solid mechanics problems. The new formulation is first established following a standard meshfree Galerkin approach for a solving of the partial differential equation of a linear elastic problem. A smoothed displacement field is introduced to the Galerkin formulation and leads to a regularized smoothed strain approximation. The resultant smoothed/regularized strain formulation can be related to the residual-based stabilization method for the elimination of zero-energy modes in the conventional particle methods. The discretized system of equations are consistently derived within the meshfree Galerkin variational framework and integrated using a direct nodal integration scheme. The linear formulation is next extended to the large deformation and failure analyses of inelastic materials. In the severe deformation range, adaptive Lagrangian or Eulerian kernel approach can be preformed to reset the reference configuration and maintain the injective deformation mapping at the particles. Several numerical benchmarks are provided to demonstrate the effectiveness and accuracy of the proposed method.

• An inverse approach for material parameter identification in a cyclic bending test using LS-DYNA and LS-OPT

  Per-Anders Eggertsen - Chalmers University of Technology, Kjell Mattiasson - Chalmers University of Technology / Volvo Cars Safety Centre

  The residual stresses in the blank after forming are the main cause for the subsequent springback in a sheet forming operation. The accuracy of the predicted springback in a Finite Element simulation of the forming operation is very much determined by the quality of the material modeling. Those parts of the workpiece, which in particular contribute to the global springback, have usually been subjected to a bending/unbending deformation mode, when the sheet material has slipped over a tool radius. It is thus of utmost importance that the material model can accurately describe the material response, when it is subjected to such a deformation mode. This is considered by the so-called "hardening law" of the material model. In this context the terms "kinematic" or "mixed" hardening are frequently employed. There are numerous such hardening models described in the literature. Common for them all is that they involve material parameters, which have to be determined from some kind of cyclic test. In theory, the most simple and straight forward test is a tensile/compression test of a sheet strip. In practice, however, such a test is very difficult to perform, due to the tendency of the strip to buckle in compression. In spite of these difficulties some successful attempts to perform cyclic tension/compression tests have been reported in the literature. However, common for these tests has been that rather complicated test rigs have been designed and used in the experiments, in order to prevent the sheet strip from buckling. Another method that frequently has been used for the determination of material hardening parameters is the three-point bending test. The advantage of this test is that it is simple to perform, and standard test equipments can be used. The disadvantage is that the material parameters have to be determined by some kind of inverse approach. The current authors have previously, successfully been utilizing this method. In the test the applied force and the corresponding displacement are recorded. The test has then been simulated by means of the Finite Element code LS-DYNA, and the material parameters have been determined by finding a best fit to the experimental force-displacement curve by means of the optimization code LS-OPT, based on a Response Surface Methodology. A problem is, however, that such simulations can be quite time consuming, since the same Finite Element model has to be analyzed numerous times. In the current paper an alternative numerical methodology is described, in which the Finite Element problem only has to be solved a limited number of times, and, thus, considerably reducing the computational cost. In this new methodology a computed moment-curvature curve is fitted to an experimental one. A complicating factor is, however, that all information to determine a moment- curvature relation is not available directly from the experiment. Therefore, the problem has to be solved in two nested iteration loops, where the optimization loop is contained within an outer loop, in which the FE-analysis is performed. It is demonstrated that the parameters determined by this new method correspond excellent to the ones determined by the conventional method.

• An inverse approach for material parameter identification in a cyclic bending test using LS-DYNA and LS-OPT

  Per-Anders Eggertsen - Chalmers University of Technology, Kjell Mattiasson - Chalmers University of Technology / Volvo Cars Safety Centre

  The residual stresses in the blank after forming are the main cause for the subsequent springback in a sheet forming operation. The accuracy of the predicted springback in a Finite Element simulation of the forming operation is very much determined by the quality of the material modeling. Those parts of the workpiece, which in particular contribute to the global springback, have usually been subjected to a bending/unbending deformation mode, when the sheet material has slipped over a tool radius. It is thus of utmost importance that the material model can accurately describe the material response, when it is subjected to such a deformation mode. This is considered by the so-called "hardening law" of the material model. In this context the terms "kinematic" or "mixed" hardening are frequently employed. There are numerous such hardening models described in the literature. Common for them all is that they involve material parameters, which have to be determined from some kind of cyclic test. In theory, the most simple and straight forward test is a tensile/compression test of a sheet strip. In practice, however, such a test is very difficult to perform, due to the tendency of the strip to buckle in compression. In spite of these difficulties some successful attempts to perform cyclic tension/compression tests have been reported in the literature. However, common for these tests has been that rather complicated test rigs have been designed and used in the experiments, in order to prevent the sheet strip from buckling. Another method that frequently has been used for the determination of material hardening parameters is the three-point bending test. The advantage of this test is that it is simple to perform, and standard test equipments can be used. The disadvantage is that the material parameters have to be determined by some kind of inverse approach. The current authors have previously, successfully been utilizing this method. In the test the applied force and the corresponding displacement are recorded. The test has then been simulated by means of the Finite Element code LS-DYNA, and the material parameters have been determined by finding a best fit to the experimental force-displacement curve by means of the optimization code LS-OPT, based on a Response Surface Methodology. A problem is, however, that such simulations can be quite time consuming, since the same Finite Element model has to be analyzed numerous times. In the current paper an alternative numerical methodology is described, in which the Finite Element problem only has to be solved a limited number of times, and, thus, considerably reducing the computational cost. In this new methodology a computed moment-curvature curve is fitted to an experimental one. A complicating factor is, however, that all information to determine a moment- curvature relation is not available directly from the experiment. Therefore, the problem has to be solved in two nested iteration loops, where the optimization loop is contained within an outer loop, in which the FE-analysis is performed. It is demonstrated that the parameters determined by this new method correspond excellent to the ones determined by the conventional method.

• An Inverse Approach to Identify the Constitutive Model Parameters for Crashworthiness Modeling of Aluminum Honeycombs and Moving Deformable Barriers

  Murat Buyuk, Cing-Dao (Steve) Kan, Shaun Kildare, Dhafer Marzougui, Hasan Kurtaran - The George Washington University

• An Investigation into the Relationship between Wood Bat Durability and Bat Taper Geometry using LS-DYNA ®

  Joshua Fortin-Smith, James Sherwood, Patrick Drane (University of Massachusetts Lowell Baseball Research Center), David Kretschmann (U.S. Forest Products Laboratory)

  Changes in the Wooden Baseball Bat Standards (WBBS) by the Office of the Commissioner of Baseball in cooperation with the MLB Players Association in response to recommendations made by a task force comprised wood and baseball science experts have produced a 65% reduction in the rate of multi-piece failures (MPFs) of bats since 2008. It is hypothesized that the rate of MPFs can be further reduced if regulations on the allowable geometries of the taper region for the bats used by MLB teams are implemented in the WBBS. To develop a fundamental understanding of the relationship among (1) the angle of the taper region of the bat, (2) the starting point of the taper along the length of the bat, and (3) wood density, a series of actual and generic bat profiles was investigated using LS-DYNA for bat/ball impacts. In this paper, the results of these bat/ball impact simulations are shared, and a summary of the various combinations of these geometric parameters on bat stress and strain is presented. The durability information gained from these studies is then used to develop an understanding of why certain bat profiles used in professional baseball have relatively high rates of MPFs while other profiles exhibit relatively low rates of MPFs.

• An Investigation of AL7075-T651 Plate Perforation Using Different Projectile Nose Shapes

  B. Balaban, İ. Kurtoğlu (FNSS Savunma Sistemleri)

  In this study, the ballistic resistance of monolithic and double-layered plates made of AL7075-T651 are evaluated using the non-linear finite element code LS-DYNA®. Plate simulations are carried out using 20 mm diameter, 197g mass hardened steel projectiles with blunt and ogival nose shapes. Penetration simulations of 20 mm monolithic plates made of AL7075-T651 are performed with both Lagrange and ALE methods and the results are compared with literature experimental studies.

• An Investigation of Maple Wood Baseball Bat Durability as a Function of Bat Profile using LS-DYNA®

  Blake Campshure, Patrick Drane, James Sherwood (University of Massachusetts Lowell)

  During the 2008 Major League Baseball (MLB) season, there was a perception that the rate at which wood bats were breaking was increasing. MLB responded by implementing changes to the wood bat regulations that were essentially transparent to the players, e.g. changing the orientation for the hitting surface on maple bats, setting a lower bound on wood density, and reducing the allowable range for the slope of grain (SoG) of the wood used to make bats. These new regulations resulted in a 65% reduction in the wood-bat breakage rate. It is proposed that a further reduction can be realized by accounting for the role that bat profile plays with respect to bat durability. To begin to develop an understanding of this relationship, a parametric study was conducted using a finite element model on three baseball bat profiles made from maple wood. These bat profiles that span a range of volumes were examined using LS-DYNA to observe their response to bat/ball impacts over a range of game-like speeds. The Altair HyperMesh and LS-PrePost® pre-processors were used in the making of the geometric representation and finite element meshing of the models. The mechanical behavior of the maple wood and its fracturing were modeled using the *MAT_WOOD material model in combination with the *MAT_ADD_EROSION option, respectively. The effective wood material properties were varied as a function of wood density. Results include how bat profile and SoG influence bat durability, where durability is defined as the relative bat/ball speed that results in crack initiation, i.e. the higher the breaking speed, the better the durability. The effective durability of the bat as a function of profile was found to be well predicted by the LS DYNA modeling.

• An Investigation of Modeling Approaches for Material Instability of Aluminum Sheet Metal using the GISSMO Model

  G. Falkinger (Leichtmetallkompetenz­zentrum Ranshofen LKR), P. Simon (AMAG Rolling)

  The most generally accepted tool for the assessment of formability of sheet material up to the present date is the forming limit diagram (FLD). It allows the identification of critical areas in a sheet - forming simulation where critical thinning or the appearance of cracks is to be expected. The FLD is determined experimentally in Nakajima tests and is widely used in the design of sheet forming processes . However it is known that the assessment based on the FLD is incomplete.

• An Investigation of Structural Optimization in Crashworthiness Design Using a Stochastic Approach

  Larsgunnar Nilsson, Marcus Redhe - Engineering Research Nordic AB, Sweden

  In this paper the Response Surface Methodology (RSM) and the Stochastic Optimization (SO) are compared with regard to their efficiency and applicability in crashworthiness design. Optimization of simple analytic expressions and optimization of a front rail structure are application used in order to assess the respective qualities of both methods. A low detailed vehicle structure is optimized to demonstrate the applicability of the methods in engineering practice. The investigations reveal that RSM is favoured compared to SO for less than 10-15 design variables. A novel zooming method is proposed for SO, which improve its convergence behaviour. A combination of both the RSM and the SO is efficient. Stochastic Optimization can be used in order to determine an appropriate starting design for an RSM optimization, which continues the optimization. Two examples are investigated using this combined method.

• An Investigation of the Application of Bolt Pre- Stress and its Effect during Low Speed Impact Loading

  A. Sean Duvall - AMEC

  This report is an initial investigation in to the effect of pre-stress of bolts during impact. The conclusions are not definitive but do indicate that for large strain analysis the effect of pre-stress in bolts is minimal. The effects are more noticeable for lateral impacts than in axial impacts. Further investigation is required to determine the effects of including friction and for other bolted configurations. This report is not an AMEC document and is not subject to AMEC procedures.

• An Investigation of the Application of Bolt Pre- Stress and its Effect during Low Speed Impact Loading

  A. Sean Duvall - AMEC

  This report is an initial investigation in to the effect of pre-stress of bolts during impact. The conclusions are not definitive but do indicate that for large strain analysis the effect of pre-stress in bolts is minimal. The effects are more noticeable for lateral impacts than in axial impacts. Further investigation is required to determine the effects of including friction and for other bolted configurations. This report is not an AMEC document and is not subject to AMEC procedures.

• An Investigation on the Roll-Over Crashworthiness of an Intercity Coach, Influence of Seat Structure and Passenger Weight

  Kadir Elitok, Dr. Mehmet A. Guler, Bertan Bayram - Product Development Dept., TEMSA A.S., Dr.-Ing. Ulrich Stelzmann - CADFEM GmbH

  A roll-over event is one of the most crucial hazards for the safety of passengers and the crew riding in a bus. In the past years it was observed after the accidents that the deforming body structure seriously threatens the lives of the passengers, thus the roll-over strength has become an important issue for bus and coach manufacturers. Today the European regulation “ECE-R66” is in force to prevent catastrophic consequences of such roll-over accidents thereby ensuring the safety of bus and coach passengers. According to the said regulation the certification can be gained either by full-scale vehicle testing, or by calculation techniques based on advanced numerical methods(i.e. non-linear explicit dynamic finite element analysis). The quantity of interest at the end is the bending deformation enabling engineers to investigate whether there is any intrusion in the passenger survival space(residual space) along the entire vehicle. In this paper, explicit dynamic ECE-R66 roll-over crash analyses of a stainless-steel bus under development were performed and the strength of the vehicle is assessed with respect to the requirements of the official regulation. Subsequently, different considerations which are not currently mentioned in the regulation (i.e. passenger and luggage weight) and some worst case assumptions such as the influence of the seat structure were investigated. The non-linear explicit dynamics code LS-DYNA as a solver and ANSA and LS-PREPOST softwares as FEA pre/post- processors were utilized throughout the bus roll-over analysis project. The FEA model was generated by using PCs running on Linux Suse operating system whereas the LS-DYNA solutions were performed on a multiple-processor workstation running on an AIX UNIX operating system. During the first stage, a verification of the calculation procedure following regulation ECE-R66 was performed. The verification of calculation is a compulsory requirement of the regulation, as it is the technical service’s responsibility(TÜV Süddeutschland in this case) to verify the assumptions used in the finite element analysis.

• An Investigation to Compare the Application of Shell and Solid Element Honeycomb Model in ODB

  Mehrdad Asadi - Cellbond, Brian Walker - ARUP, Hassan Shirvani - Anglia Ruskin University

  Cellbond and ARUP have launched their advanced crash barrier models in 2006 and since the time a continuous study has been carried out to distinguish costumer requirements and review feedbacks. Existing barrier models are constructed using the solid element configuration in honeycomb segments along with validated Modified_Honeycomb material cards. Due to a number of demands on using Shell based honeycomb model in crash barriers by car manufacturers, it was decided to investigate the application in detail using fullscale test data. This paper represents the methodology of creating the shellbased ODB and the comparison with existing solid based FE model. Frontal Offset tests are carried out by a large number of test houses worldwide, according to the European regulation and to FMVSS, as well as by EuroNCAP, Australian NCAP, JNCAP and IIHS. In the frontal offset test, only one side of a vehicles front end hits the deformable barrier, which means that a more concentrated area of the vehicles structure must sustain the impact of the crash rather than the whole width of the vehicle. The Cellbond ODB barrier has been investigated which consists of two different sized aluminium honeycomb blocks in main body and bumper partially covered in aluminium skins. Number of static compressive tests performed to specify honeycomb and adhesive material characters. Adhesive properties are obtained using Climbing Drum, TPeel, Tensile and Plate Shear test results. The barrier was subjected to four individual test conditions with different impactor and impact speeds.

• An Investigation to Compare the Application of Shell and Solid Element Honeycomb Model in ODB

  Mehrdad Asadi - Cellbond, Brian Walker - ARUP, Hassan Shirvani - Anglia Ruskin University

  Cellbond and ARUP have launched their advanced crash barrier models in 2006 and since the time a continuous study has been carried out to distinguish costumer requirements and review feedbacks. Existing barrier models are constructed using the solid element configuration in honeycomb segments along with validated Modified_Honeycomb material cards. Due to a number of demands on using Shell based honeycomb model in crash barriers by car manufacturers, it was decided to investigate the application in detail using fullscale test data. This paper represents the methodology of creating the shellbased ODB and the comparison with existing solid based FE model. Frontal Offset tests are carried out by a large number of test houses worldwide, according to the European regulation and to FMVSS, as well as by EuroNCAP, Australian NCAP, JNCAP and IIHS. In the frontal offset test, only one side of a vehicles front end hits the deformable barrier, which means that a more concentrated area of the vehicles structure must sustain the impact of the crash rather than the whole width of the vehicle. The Cellbond ODB barrier has been investigated which consists of two different sized aluminium honeycomb blocks in main body and bumper partially covered in aluminium skins. Number of static compressive tests performed to specify honeycomb and adhesive material characters. Adhesive properties are obtained using Climbing Drum, TPeel, Tensile and Plate Shear test results. The barrier was subjected to four individual test conditions with different impactor and impact speeds.

• An Ivestigation into Modeling Approaches for the Dynamic Response of a Shipping Container Cart and Suspended Automotive Parts under Random Base Excitation using LS-DYNA

  Prof. S. Noll, A. Ramanathan (Ohio State University); E. DeHoff, R. Rittenhouse (Honda)

  Shipping containers are exposed to complex dynamic loading conditions during transport via truck, rail, and air. The loading conditions are further complicated by contact nonlinearities between the cart and ground, between cart holders and suspended parts, and between neighboring suspended parts. This study focuses on developing a modeling strategy to simulate a container cart with parts undergoing ASTM D4728 truck random vibration tests. Initially, the linear frequency-domain properties and response to a random excitation profile of the cart structure were examined and correlated with experimental measurements. The linear response predictions lacked the required modeling fidelity to capture the nonlinear dynamic behavior observed during the testing as the input power spectral density profile was increased to higher levels. Thus, the nonlinear response was then simulated in the time domain using the explicit integration method in LS-DYNA®. The use of LS-DYNA® also allowed the simulation of the complex contact-driven boundary conditions. The total run time was determined to be prohibitively long for the second approach as the time step size was 0.3 μsec for the required simulation duration of more than 5 sec. Finally, a dynamic substructuring strategy was employed through the use of super elements. This final approach captured the dynamic amplification of the cart, maintained the contact nonlinearities, and reduced the total run times. This modeling approach in LS-DYNA® appears promising to capture the complex dynamic loading conditions affecting shipping containers in a computationally efficient manner.

• An LS-DYNA material model for simulations of hot stamping processes of ultra high strength steels

  Dr. Tobias Olsson - Engineering Research Nordic AB

  This paper present a new material model (*MAT_244) in LS-DYNA capable of simulating phase transition during quenching and forming. Usually during forming the blank is initially heated to become fully austenitized and then continuously formed and cooled. When the temperature is decreasing the austenite decomposes into different product phases. The amount of each phase does not only depend on the mechanical history, but also on the cooling rate of the blank. A higher cooling rate increases the amount of the harder phases (bainite and martensite) whereas a slow process gives higher content of ferrite and pearlite. This thermo-elastoplastic model is based on the isotropic von-Mises yield criterion with an associated plastic flow rule. It includes both the decomposition of austenite into ferrite, pearlite, bainite and martensite, and transformation plasticity. The examples show that the model is well suited for hot stamping simulations and it should be possible to simulate different steel compositions at different cooling rates to obtain a good prediction of the hardening process and the properties of the final product.

• An LS-DYNA material model for simulations of hot stamping processes of ultra high strength steels

  Dr. Tobias Olsson - Engineering Research Nordic AB

  This paper present a new material model (*MAT_244) in LS-DYNA capable of simulating phase transition during quenching and forming. Usually during forming the blank is initially heated to become fully austenitized and then continuously formed and cooled. When the temperature is decreasing the austenite decomposes into different product phases. The amount of each phase does not only depend on the mechanical history, but also on the cooling rate of the blank. A higher cooling rate increases the amount of the harder phases (bainite and martensite) whereas a slow process gives higher content of ferrite and pearlite. This thermo-elastoplastic model is based on the isotropic von-Mises yield criterion with an associated plastic flow rule. It includes both the decomposition of austenite into ferrite, pearlite, bainite and martensite, and transformation plasticity. The examples show that the model is well suited for hot stamping simulations and it should be possible to simulate different steel compositions at different cooling rates to obtain a good prediction of the hardening process and the properties of the final product.

• An LS-DYNA Model for the Investigation of the Human Knee Joint Response to Axial Tibial Loadings

  Dr. Chiara Silvestri, Doug Heath, Prof. Dr. Malcolm H. Ray - Worcester Polytechnic Institute

  Automotive accidents frequently involve fracture of the knee joints which can be related to either bone or soft tissue injuries. Previous studies show that the degree of anterior-posterior constraint of the femur bone along its longitudinal axis plays a crucial role in determining the knee-joint-fracture mechanism and internal tibial-femoral load distribution. Also, the anatomical tilt of the tibial plateau, tibial-femoral joint compression results in anterior displacement of the tibia, which has important implications in the prediction of knee injury and might lead to anterior cruciate ligament rupture. This study aimed at validating an existing finite element LS-DYNA® human knee joint model for replication of these complex failure mechanisms when the joint is subjected to tibial axial compression loads. Simulations were run with the joint at 90 ̊ flexion to investigate the effects of anterior-posterior joint constraint on the injury patterns. Comparisons between simulations findings and test outcomes from literature were compared in terms of anterior- posterior and medial displacements of the femur, proximal rotation of the tibia and tibial-femoral load distribution. The finite element model predicted similar injury patterns and internal loads resulted with cadaveric specimen testing. The validated numerical model can be integrated in a complete replication of the human lower extremity and employed in simulations of knee-bolster impacts with the human leg during car crashes. It would be used to predict leg injury patterns with the knee joint subjected to simultaneously axial loading of the femur and the tibia bones.

• AN LS-DYNA USER DEFINED MATERIAL MODEL FOR LOOSELY WOVEN FABRIC WITH NON-ORTHOGONAL VARYING WEFT AND WARP ANGLE

  Marlin Brueggert, Romil R. Tanov - Center for Advanced Product Evaluation, Division of IMMI

  The behavior of loosely woven fabrics (LWF) differs significantly from other types of woven fabric materials, the major difference being the significant change that the angle between the weft and warp fibers undergoes as the fabric stretching forces change. These unique characteristics have made the LWF a very important part for the functionality of some recently developed occupant protection safety devices for the automotive and heavy machine and truck industry. To efficiently model and analyze the behavior of such devices within an occupant protection model, an accurate representation of the characteristics of the LWF is needed. However, none of the many available LS-DYNA material models seem to fit well with the unique kinematics of the LWF. Therefore, the aim of this work is to present the basics of a formulation for a material model for the analysis of LWF and its implementation as a user defined material in LS-DYNA. To assess the performance of the model, results from the simulation are presented. Although relatively simple, the developed model seems to represent very well the behavior of the LWF and the simplicity of the formulation attributes to the efficiency and stability of the user defined material subroutine.

• An LS-OPT® methodology for utilizing partial curve data for the calibration of material models

  N. Stander, A. Basudhar (LSTC), S. Du Bois (DYNAmore),

  Parameter estimation is a considerably large application area of optimization. It fulfills the important purpose of characterizing materials based on models available in Finite Element analysis software such as LS-DYNA®. The development of special LS-OPT® features for parameter estimation using Digital Image Correlation and other experimental methods has been ongoing for a number of years. In earlier papers [1,2] some of the available similarity measures as well as the LS-OPT DIC methodology were discussed in broad detail and illustrated with examples.

• An MPP Version of the Electromagnetism Module in LS-DYNA for 3D Coupled Mechanical-Thermal-Electromagnetic Simulations

  P. L'Eplattenier, C. Ashcraft - Livermore Software Technology Corporation, I. Ulacia - Mondragon Goi Eskola Politeknikoa

  A new electromagnetism module is being developed in LS-DYNA for coupled mechanical/thermal/electromagnetic simulations. One of the main applications of this module is Electromagnetic Metal Forming (EMF). The electromagnetic fields are solved using a Finite Element Method (FEM) for the conductors coupled with a Boundary Element Method (BEM) for the surrounding air/insulators. Both methods use elements based on discrete differential forms for improved accuracy . Recently, a Massively Parallel Processing (MPP) version of the EM module was developed allowing sharing the CPU and memory between different processors and thus faster computations on larger problems. The implementation of the FEM and BEM in MPP will be presented. The EM module will then be illustrated on an actual EMF case. Experimental and numerical results will be compared and the speed-up of the MPP version will be studied. Finally, a new contact capability for the electromagnetic fields will be presented and illustrated on a rail gun simulation.

• An Objectivity Algorithm for Strain Softening Material Models

  Mauricio V. Donadon, Lorenzo Iannucci - Imperial College London

  Predictive techniques for the analysis and design of metallic or composite components and structures subject to severe loading can lead to significant mesh sensitivity if cracking or tearing or penetration occurs. This is especially important for composite materials in which the material has an elastic brittle response with little or no plastic behaviour, in which energy could be dissipated. Hence, the full potential use of composite in the design of advanced composites and structures has not yet been exploited fully. This work constitutes an effort directed towards the development of an objectivity algorithm for strain softening material models based on the ‘smeared cracking formulation’. The algorithm has been implemented into LS-DYNA for hexahedron solid elements and correctly accounts for crack directionality effects. Thus enabling the control of energy dissipation associated with each failure mode regardless of mesh refinement and element topology. The advantage of the present technique is that mesh size sensitivity on failure is removed leading to results, which converge to a unique solution, as the mesh is refined. If such a scheme were not introduced results could change significantly from mesh to mesh leading to an incorrect structural response. The proposed algorithm has been validated by a series of benchmark tests using different degrees of mesh refinement and element topologies.

• An Optimization Procedure For Springback Compensation Using LS-OPT

  Nielen Stander, Mike Burger, Xinhai Zhu, Bradley Maker - Livermore Software Technology Corporation

  The purpose of this study is to develop a methodology for springback compensation in sheet metal stamping operations. An optimization method is employed to minimize the difference between the simulation results and the intended design. This procedure results in an optimized die shape. LS-DYNA, LS-OPT and TrueGrid are used to input original tool geometry, material, and process parameters, identify design variables, perform springback simulations, and output optimized tool geometry. It is found that springback trends are consistent with changes in the die shape, which provides an effective strategy for springback compensation. The standard NUMISHEET’96 S-Rail is used as a benchmark example in this study.

• An Overview of LS-OPT Version 4.1

  Nielen Stander, Tushar Goel - Livermore Software Technology Corporation

  The main focus of the LS-OPT V4.1 development has been to further expand the graphical postprocessor and to significantly improve reliability, usability and transparency when distributing solver jobs across networks. Much of the latter has been accomplished through industrial collaboration. While LS-OPT originated as an LS-DYNA® based tool, new features are increasingly being developed to facilitate interfacing with non-LS-DYNA solvers. This is necessitated by the increasing requirement for conducting multidisciplinary optimization, thereby involving more than one solver type. Therefore, in V4.1, LS-OPT now has MSC NASTRAN support for mode tracking and frequency extraction. A generic extractor has also been added to aid result extraction from text files.

• An Overview of User Defined Interfaces in LS-DYNA

  Tobias Erhart - Dynamore GmbH

  The user-defined features in LS-DYNA are powerful tools that allow users in academia or industry to verify research results in the context of general and complicated finite element applications. Implementation work concerns only the special field of interest, and there is no need for the comprehensive task of developing and maintaining the complete finite element software. The most popular user interface is for material modeling. But there also exist user interfaces for structural elements, airbag sensors, solution control, friction, interface control, weld failure, loads, output control, adaptivity, thermal contact, and others. An overview of current user-defined interfaces in LS-DYNA version 971 R5.0 will be presented. The aim of this contribution is to bring together the possibilities to add own numerical models and algorithms to the code. Therefore, each interface is described in its functionality. It will be explained, how to activate the particular interface in the input, where to find the corresponding subroutine, and which input/output arguments can be used.

• AN UPDATED TOOLBOX FOR VALIDATION AND UNCERTAINTY QUANTIFICATION OF NONLINEAR FINITE ELEMENT MODELS

  Keng C. Yap, G. Wije Wathugala, Timothy K. Hasselman - ACTA Inc.

  It is becoming commonplace to use numerical simulations supported by limited experimentation for the characterization of physical phenomena. This trend, with its perceived potential for reducing costs, is the basis for the simulation-based procurement initiatives currently gaining momentum within the government and industry. Insuring the quantitative viability of a simulation-based procurement still requires some experimental data upon which the assessment of simulation accuracy can be based. In addition, it requires minimizing the differences between corresponding analytical and experimental results in physically meaningful ways, and characterizing the ability of the models to predict future events. The purpose of model validation and uncertainty quantification is to confirm the correctness and credibility of numerical simulations, so that the underlying models may be used with greater confidence to extrapolate limited test experience to a range of practical applications. In this paper, an advanced principal components-based computational procedure is demonstrated by validating the DYNA models used to achieve HFPB numerical simulations of physical processes important to assessing weapon- target interaction. Bayesian statistical parameter estimation is used to estimate material parameters that cannot be measured directly, such as strain rate enhancement and shear dilatency in reinforced concrete structures. This demonstration is performed using an updated MATLAB® Nonlinear Model Validation and Verification Toolbox. The work reported in this paper has resulted in improvements to the original Toolbox. A multi-level parameter estimation procedure is implemented to sequentially accumulate information from prior estimates in a Fisher information matrix for use in subsequent parameter estimates. The use of a generic uncertainty model in estimating the predictive accuracy of future DYNA simulations is enhanced through the use of a reduced set of principal component metrics and a basis augmentation technique.

• Analysis and Design of a Unique Security Bollard Installment Using LS-DYNA® for a K12 Vehicle Impact

  Joseph M. Dulka, Eric R. Dietrich, Kelley S. Elmore, Kendra D. Jones, Clyde S. Harmes, Robert H. Moyer (elmore engineering)

  This paper presents the design process for a unique security bollard providing protection against a K12 [1] (M50 [2]) vehicle crash load. LS-DYNA was used to aid in the design of the security bollard to account for the highly dynamic and inelastic behavior during a vehicle impact. The bollard was installed along the top of a wall for a below-grade courtyard in order to maintain a building security perimeter, providing protection against a potential malevolent vehicle attack. Contrary to typical bollard installations where the foundation is supported on all sides with well compacted soil or other substrata, no significant support was provided on the protected side of the bollard foundation. As a result, this posed significant difficulty in the design of an effective security bollard required to resist a potential K12 (M50) vehicle impact load with zero vehicle penetration. The initial conceptual bollard design originated from the standard Department of State (DoS) DS-22 K-12 rated bollard system [3]. Hand calculations were used to develop a preliminary bollard design with equivalent static design stopping forces based upon existing physical K12 test results. LS-DYNA aided the engineering team in observing structural and material responses characteristic of impact loading which may have otherwise not been perceived by method of traditional hand calculations. Utilizing LS-DYNA as not only an analysis tool, but a powerful design tool enabled the engineering team to optimize the design of the security bollard.

• Analysis and Design of Large-Scale Civil Works Structures Using LS-DYNA

  David DePolo, Eric Kennedy, Thomas Walker, Ryan Tom - US Army Corps of Engineers

  The Folsom Joint Federal Project (JFP) Auxiliary Spillway is a high profile addition to the Folsom Dam, located approximately thirty miles upstream of Sacramento, California. Total concrete placements on the project will exceed 140,000 cubic yards at a projected cost of nearly $1 billion. The main component of the JFP is a large concrete control structure with steel bulkhead gates, submerged tainter gates, and post-tensioned anchorage. As a critical piece of the flood control system in a densely populated, active seismic region, the JFP demanded a rigorous analysis of a scale never before used by the U.S. Army Corps of Engineers to design a civil works structure. The Sacramento District of the Corps developed a three-dimensional LS-DYNA model of the control structure, foundation, and reservoir in order to capture the fluid-structure and soil-structure interaction during a seismic event, something not possible with standard dam analysis procedures. The model incorporated anomalies within the foundation; their effects were significant and could not have been established and properly accounted for without the LS-DYNA model. The analysis examined seven suites of ground motions and two pool elevations that envelope the expected demand on the structure. Results from the model were used for both evaluation and design purposes. This paper presents suggestions on the modeling of large scale civil works structures such as the JFP. Included is an overview of lessons learned regarding contact definitions and troubleshooting, the application and scaling of seismic input, and methods for accurately modeling the behavior and load paths. Extensive verification of the LS- DYNA results was conducted using another widely used finite element analysis program; the procedures and results are discussed. Additionally, the paper advises on items to be considered during model development, with a focus on generating output suitable for design.

• Analysis and Optimization of Aluminum Automobile Side Door Design Using LS-DYNA® Implicit and LS-OPT®

  Akshay Kulkarni, Richard Newton (Novelis Inc.)

  Vehicle design and development involves various types of linear and non-linear finite element analyses. Using different solvers for different types of analyses is not always a cost-effective solution. Using one solver for multiple types of analysis saves cost as well as it allows sharing CAE models between various disciplines. Although LS-DYNA historically has been used for explicit analysis, recent enhancements in LS-DYNA Implicit enable it to be used for various implicit analyses. This work focuses on the analysis and optimization of an automobile side door assembly made of aluminum, using LS-DYNA Implicit Solver for multiple load cases. A combination of Novelis’s high formable and high strength aluminum alloys were used in the door design. Implicit load cases used for this analysis were – modal analysis, door sagging, door frame stiffness, and beltline stiffness. LS-DYNA Implicit models were further used for setting up DOE and design optimization. LS-OPT tool was used to conduct multi-response DOE studies and optimization to minimize the door weight while meeting all the performance requirements. Additionally, the DOE runs results were combined with Excel cost model results to choose an optimal design that balanced the total mass of the door versus the cost to manufacture. A final validation simulation was run to demonstrate the optimized design met all expected performance requirements.

• Analysis and Testing of a Composite Fuselage Shield for Open Rotor Engine Blade-Out Protection

  J. Michael Pereira, Charles R. Ruggeri, Duane M. Revilock (NASA Glenn Research Center), William Emmerling (FAA William J. Hughes Technical Center, Atlantic City), Silvia Seng, Charles Frankenberger (Naval Air Warfare Center, China Lake), Kelly S. Carney (George Mason University)

  The Federal Aviation Administration is working with the European Aviation Safety Agency to determine the certification base for proposed new engines that would not have a containment structure on large commercial aircraft. Equivalent safety to the current fleet is desired by the regulators, which means that loss of a single fan blade will not cause hazard to the Aircraft. The NASA Glenn Research Center and The Naval Air Warfare Center (NAWC), China Lake, collaborated with the FAA Aircraft Catastrophic Failure Prevention Program to design and test lightweight composite shields for protection of the aircraft passengers and critical systems from a released blade that could impact the fuselage. LS-DYNA ® was used to predict the thickness of the composite shield required to prevent blade penetration. In the test, two composite blades were pyrotechnically released from a running engine, each impacting a composite shield with a different thickness. The thinner shield was penetrated by the blade and the thicker shield prevented penetration. This was consistent with pre-test LS-DYNA predictions. This paper documents the analysis conducted to predict the required thickness of a composite shield, the live fire test from the full scale rig at NAWC China Lake and describes the damage to the shields as well as instrumentation results.

• Analysis of a Propane Tank Truck Impacting a Concrete Column Using LS-DYNA

  Clayton F. Heberling - Pressure Sciences, Inc.

  Pressure Sciences Inc. used LS-DYNA to model a propane tank truck colliding with a concrete column. The analysis simulates an accident that occurred in 1994 in White Plains, New York. Correlation between the accident and an LS-DYNA analysis of that crash is described. The ultimate purpose of the analyses is to improve the crashworthiness of propane semi-trailers. To address the stiffening effect of the propane fluid, we correlated several models with drop tests that had been performed on 1/12 scale railroad tank car heads. The heads included unpressurized heads, fluid pressurized heads, and fluid pressurized heads with an air cushion. In order to model the liquid propane, explicit solid elements were used. The material model used for the propane was the elastic material model with the fluid option. The paper describes the procedure used to incorporate the elastic material model with the fluid option. The propane vapor was modeled using explicit solid elements and the null material model with a linear polynomial equation of state. The paper gives the derivation of a simplified version of the linear polynomial equation of state to simulate Boyle’s law. We were able to use LS-DYNA to obtain good correlations with drop tests when we modeled the liquid using the elastic material model with the fluid option and the vapor with a null material with the linear polynomial equation of state. We also obtained reasonable correlations between our LS-DYNA model and the White Plains, NY accident involving a propane tank truck and a concrete column.

• Analysis of a single stage compressed gas launcher behaviour : from breech opening to sabot separation

  F. Plassard, J. Mespoulet, P. Hereil - Thiot-Ingenierie

  Single stage compressed gas guns are used in Shock Physics laboratory to perform characterization experiments and ballistic events. The main advantage of this kind of launcher is that impact conditions are well defined (impact obliquity, impact velocity). In order to achieve high quality in ballistic performance, it is essential to understand the behaviour of the projectile in the barrel of the gun. This paper is devoted to the simulation of the whole behaviour of a laboratory gun, from breech opening up to the muzzle blast sabot separation due to air drag forces. LSDYNA was used as a numerical tool for the improvement of the launched package behaviour which consists in sabots and projectile. The simulation needs to reproduce the in-bore operations of a launcher taking into account gases which act on both sides of the projectile: very high pressures release at the base as well as pressure built-up and the gas thrown out from the tube at the front. There is also a need to predict perfectly the sabots behaviour when the projectile is released from the tube so as to control the impact conditions on the target. The Fluid / Stucture Interaction (FSI) capability of LSDYNA is used as a numerical tool to increase the knowledge in this field. The challenge is to obtain a simulation recreating the effect of gases on the projectile at both high pressures and high velocities. High speed and ultra high speed video cameras set up in our facility allow us to make correlation between calculations and experiments and so validate the simulation. This work gives to our Laboratory a real tool for optimizing the sabots design in terms of material, shape, dimensions and thus increases the quality and reliability of ballistic experiments.

• Analysis of Extended End-Plate Connections Under Cyclic Loading Using the LS-DYNA Implicit Solver

  Ashish Bhargava, W.M. Kim Roddis, Dhafer Marzougui, Pradeep K. Mohan - The George Washington University

  Moment-Resisting Frames (MRF’s) are widely used as lateral-force resisting systems in buildings. Their successful performance depends on the behavior of their moment-resisting beam-column connections. In regions at risk for earthquakes, MRF’s need to resist large cyclic forces and displacements. A variety of beam-column connections are used in practice. Most, including end plate connections, are designed assuming the MRF seismic capacity is based on the ability of the connection to allow inelastic rotation through the development of plastic hinges within the beam elements of the structure. In this paper, Finite Element (FE) computer analysis is used to simulate the behavior of the joint region of an MRF. A computer model of the MRF’s extended end plate beam-column connection was created and its performance was analyzed under cyclic loading condition. The LS-DYNA implicit solver was used in this study. Results from these simulations were compared to previously conducted physical tests. The results show good correlation with the measured test data. The work demonstrates the ability of LS-DYNA to simulate the cyclic behavior of this type of beam-column connection and is a step toward using physically calibrated computational model to complement physical testing for the future evaluation of this type of structural detail.

• Analysis of Fibre Orientation using μCT Data

  Sebastian Mönnich, Robert Glöckner , Florian Becker - German Institute for Polymers (DKI)

  Integrative simulations are based on a calculated bre orientation from which the local material properties can be derived in several ways. For instance the micro-mechanical model proposed by Tandon and Weng may be used coupled with an orientation averaging approach to include the bre orientation. This approach then gives the elastic properties of the bre matrix compound with a strong dependency, of e.g. the elastic modulus, on the bre orientation. Modeling failure for nite element simulations, e.g. crash, also requires knowledge of the bre orientation, because the failure strains and energy dissipation also depend on the orientation of the bres [1, 2]. The accuracy of the calculated bre orientation depends on several simulation input parameters, which are not necessarily physical properties. The most important example is the bre interaction coecient (c). This parameter allows the user to modify the calculated bre orientation from isotropic to transversely isotropic [3]. In this paper a new experimental method to determine the bre interaction coecient is presented. The classical approach to validate the calculated bre orientation would be the usage of optical microscope images of cut surfaces of the specimen and the calculation of the bre orientation by measuring the cut ellipsis dimensions. This method is very time consuming and with respective to the necessary magnication not very accurate, because not all bres can be accounted for. The new method is using a model based algorithm to analyze three-dimensional micro computer tomography measurements. This enables the identication of up to 90% of the bres within the specimen and calculate a second order orientation tensor and the bre length distribution in any arbitrary space. Due to the fact that a model based algorithm is used, the bre detection can also be performed, if the density of the matrix polymer is near to the density of the bre material. This is a novelty to existing bre orientation measurements with computer tomography. To obtain reliable data which can be directly compared with injection moulding simulations, several steps had to be taken. First of all a representative volume must be dened, in which the bre orientation will be evaluated. This representative volume must be the same in the injection moulding simulation and the μCT measurement. As the injection moulding model is already discretized, the representative volume is set as a stack of nite elements over the part thickness. To calculate the second order orientation tensor in exactly the same geometrical space and the same coordinate system as in the injection moulding simulation, it was necessary to develop a method which allows a reconstruction of the original part from which the μCT specimen was taken. A special painting and evaluation procedure were implemented into the existing method to recalculate the original position and orientation of the specimen, enabling us to achieve the desired measurements. At the moment the determination of the bre interaction coecient requires still many injection moulding simulations, which then are compared to the measured values. This allows for a more realistic bre coecient in comparison to the default parameter. The next steps are to automate the described procedure and to correlate the measured bre orientations directly with the bre interaction coecient to avoid unnecessary simulations.

• Analysis of formability of advanced high strength steel sheets with phenomenologically based failure criteria with separate treatment of instability, shear and normal fracture

  K. Isik, C. Soyarslan, A.E. Tekkaya - Technical University of Dortmund, H. Richter - ThyssenKrupp Steel Europe AG

  Despite their wide application in sheet metal forming analysis, Forming Limit Diagrams cannot supply reliable results for the cases involving non-proportional strain paths or material classes with reduced ductility such as advanced high strength steels (AHSS). Fracture criteria appear as complimentary tools for assessment of formability in these cases. CrachFEM, as an advanced failure model, merges an instability criterion that includes strain hardening and yield loci effects with fracture criteria which monitor damage accumulation for ductile normal fracture and ductile shear fracture separately where stress triaxiality ratio and maximum shear stress dependence are taken into account, respectively. In the present study, rectangular deep drawing of two AHSS classes is studied both experimentally and numerically. Blanks with different rolling directions and blank orientations with respect to the punch are taken into account. Simulations are conducted using CrachFEM failure model and LS-DYNA where texture of the sheet due to rolling is modeled with Hill’48 type anisotropic yield locus. Experimental studies reveal that the failure occurs mainly due to instability with necking whereas in- plane shear stress state in drawing zone seems to be insufficient to create shear fracture. Numerical results show not only the predictive capability of CrachFEM but also regarding weaknesses which needs improvement for better predictions.

• Analysis of High Velocity Impact Penetration Using the Smoothed Particle Galerkin Method

  Youcai Wu, Yong Guo, C. T. Wu, Wei Hu (LSTC), Joseph Magallanes (Karagozian & Case)

  Impact penetration is a very complex multi-physics procedure, which involves localized damage, large degree of material fragmentation (failure) and separation (ejecta), complicated projectile – target interaction. The mathematical models of these problems are often ill-posed and the corresponding numerical solutions are generally non-smooth. In essence, severe mesh distortion would occur if Lagrangian finite element method (FEM) is used. Furthermore, ad-hoc erosion criteria are usually needed to model the fragmentation process for the mesh-based formulation. In this paper, the smoothed particle Galerkin (SPG) meshfree method [1] in LS-DYNA ® is tested for the analysis of this type of problems. SPG method is a pure particle method based on the nodal integration of nonlocal Galerkin weak formulation. Numerically, the SPG formulation [1-4] is designed to alleviate the zero-energy modes in the conventional meshfree method and to naturally handle the material separation during the failure process. Good agreement with experimental data was observed in the numerical results, which indicates the potential of the SPG formulation in modeling the material failure and associated debris tracking in impact penetration problems.

• Analysis of LS-DYNA MOR Approaches for Application in Crash Analysis and Integration in SDM Workflows

  Z. El Khatib, U. Reuter (TU Dresden), M. Thiele (SCALE)

  Numerical simulations are often characterized by long computational times, especially as the size of the model grows larger. In many cases, this necessitates the use of a high-performance computer in order to speed up the simulation and obtain results faster. Nevertheless, computational times can still be large, such as in the automotive and aerospace industries. The automotive industry is highly dependent on numerical modelling. Companies perform numerical simulations for crash analysis in the preliminary phases of design, because it eliminates the need to perform expensive physical crash tests of prototypes. Optimization, another time-consuming process, is also often performed during the different stages of a project and is only possible using virtual testing. However, optimization adds to the scale of computational time needed in the automotive industry for virtual product development. The longer it takes to perform such numerical processes, the longer the time-to-market of a certain vehicle model and eventually, the higher the cost.

• Analysis of Partially Confined Blast Experiments and Simulations

  Len Schwer Schwer Engineering & Consulting Services

  Data and simulation results presented by Teland et al. (2018) for incident and reflected pressure histories indicated the simulation results time of arrival and pressure magnitude did not agree well with the data for the reflected shock. They posited three possibilities for the differences: (1) Charge load (explosive mass per chamber volume), (2) Afterburning and (3) Variable Gamma for the gas mixture.

• Analysis of the Scatter of a Deploying Airbag

  R. Brown, M. Bloomfield (JaguarLandrover), C.-A. Thole, L. Nikitina (Fraunhofer Institute SCAI)

  This paper discusses some of the challenges faced by the automotive industry in dealing with the natural variation in input parameters and environmental factors that lead to scatter in results. We describe how a lack of consideration of this variation can lead to surprises during testing, with the associated risk of unplanned cost, and present a technique using Principal Components Analysis to improve the robustness of CAE crash models. In a purely virtual product development world, increasingly demanding functional requirements, and pressure on weight and cost, mean that analysis techniques must lead to designs that are robust with respect to external noise sources; large safety margins are no longer acceptable. Conventionally the CAE process has used nominal values for input parameters, and has been satisfied with single, deterministic solutions. However, virtual techniques have much to offer in understanding and managing scatter, and the consideration of variability in the CAE process is becoming more common-place. At the same time, the CAE method introduces its own issues associated with model stability, and these must also be addressed before design optimisation is attempted. Frequently, analysis approaches used to improve design robustness can also be applied to issues of model stability, and we describe an example where Principal Components Analysis within the Diffcrash software package has been used to identify a source of instability in an airbag model. The mathematical background to the PCA method is presented, explaining its application to the analysis of variation, and showing how it can help in locating a source of scatter in results. The airbag example illustrates how this can be applied to allow changes to the modelling technique (or to the design) to be made to reduce the scatter. In this example, the source of the different airbag behaviours shown in figure 1 was identified as being a contact issue at an earlier point in time (figure 2), and a modification to the contact definition led to a reduction in the dispersion in results. Lastly we offer insight into the requirements for deployment of such techniques, and describe how process integration is a fundamental necessity for a successful, sustained implementation.

• Analysis of Unsteady Aerodynamics of a Car Model in Dynamic Pitching Motion Using LS-DYNA® R7

  Yusuke Nakae, Tsuyoshi Yasuki, Hiroshi Tanaka, Jiro Takamitsu (Toyota Motor Corporation)

  This paper describes the numerical analysis of unsteady aerodynamics of a car model in dynamic pitching motion using LS-DYNA R7. Large-Eddy simulations with ALE method were performed to clarify the effects of unsteady aerodynamic forces on aerodynamic characteristics of cars in dynamic motion. The forced sinusoidal pitching oscillation was imposed on the 1/4 scaled car model and the flow velocity was set to 27.78 m/s. The model was based on a real production car and it was simplified by removing its engine compartment cavity and smoothing its surface. Tires were fixed on the ground and separated from the car body. Unsteady aerodynamic forces acting on the model were investigated. And the mechanism of the differences between the aerodynamic forces acting on the car model in the dynamic motion and those in stationary states occur was mainly discussed. The computational results showed good agreement with the results of the high accuracy LES code computations. Also, results showed the differences between the aerodynamic forces in the dynamic pitching motion and those in the stationary states. Especially, the lift force showed remarkable differences. Even in the same posture of the pitch angle 0 degree (i.e. the posture in which the under floor of the car body is parallel to the ground), the lifts showed different values at stationary state and during nose-up or nose-down respectively. As a result of this analysis, it was revealed that these differences in the aerodynamic forces were mostly due to the changes of the surface pressure distributions around rear end of the front wheelhouse. The flow structures behind the front tires changed with volume shrinking or expanding of front wheel house owing to the car motion. These changes affected the surface pressure distributions.

• Analysis of Unsteady Aerodynamics of a Car Model with Radiator in Dyna­­mic Pitching Motion using LS-DYNA

  Y. Nakae, J. Takamitsu, H. Tanaka, T. Yasuki (Toyota Motor)

  This paper describes the numerical analysis of unsteady aerodynamics of a radiator mounted car model in dynamic pitching motion using LS-DYNA ICFD solver. Large-Eddy simulations with ALE method and porous media modeling were performed to clarify the unsteady aerodynamic forces acting on cars with engine compartment in dynamic motion.

• Analyzing 'Noisy' Structural Problems with LS-OPT: Probabilistic and Deterministic Fundamentals

  Willem Roux, Nielen Stander - Livermore Software Technology Corporation

  System identification of 'noisy' structural design optimization problems: the sources of uncertainty, the competing roles of bias and variance, and the interaction of uncertainty and deterministic effects. Two test problems are used to clarify the effect of different approaches.

• Analyzing Bicycle Accidents with Human Body Models

  V. Alvarez (Lightness by Design), H. Wendelrup (Hövding), K. Brolin (Lightness by Design)

  For the past 20 years, single-bicycle accidents have been the most common cycling accidents in Sweden (more than 70% of all injuries) [1-4] and in other countries where many people use bikes as means of transportation [5-6]. Vehicles were involved in a majority of the lethal bicycle accidents. Neck injuries were a small portion of all cycling injuries, but they were associate with a large risk of permanent medical impairment. Therefore, it is interesting to explore if head protective safety devices can provide safety benefits for the neck as well. Hövding is a head protective device that is worn as a scarf around the neck, with sensors that trigger inflation of an airbag in case of an accident. Theoretically, the portion of the airbag that surrounds the neck could protect from neck injuries (see Fig. 1).

• Analyzing Elastomer Automotive Body Seals Using LS-DYNA

  Linhuo Shi - TG North America Corporation

  Several different elastomer automotive body seals (weatherstrips or weather seals) are analyzed using explicit solver of LS-DYNA. The results are compared with those obtained from non-linear finite element analysis (FEA) solvers widely used for elastomer analysis as well as the experimental results. It is found that properly modeled LS-DYNA can be a very good tool for elastomer body seal analysis, especially for the analysis with potential instabilities, such as snap-through, loss-of-contact, severe slip-stick, and complicated contact problems.

• Anatomically accurate finite element model of a human head for crash applications

  Alberto Tacchi, Ivan Colamartino, Gabriele Canzi, Giorgio Novelli, Marco Anghileri

  Every year road traffic accidents are responsible of approximately 1.3 million deaths in the world, resulting in one of the main causes of mortality. According to the World Health Organization (WHO), by the 2020s road traffic accidents will be the leading cause of premature death. Moreover, between 20 and 50 million people involved in incidents suffer non-fatal injuries, most of them leading to disabilities [1]. These injuries considerably affect individuals, their families, and nations from both social and economic points of view. Over the last 60 years, experimental activities focused on the impact behavior of the human body were carried out with crash dummies and human cadavers, expanding the available injury database, exposing the most common injury scenarios and allowing the development of effective predictive criteria. The most frequently injured body regions resulted to be head and lower limbs; however severe to fatal injuries (Abbreviate Injury Scale values AIS 3+), are more commonly related to head impacts, as shown in Figure 1 [2].

• Anisotropic Behaviors and Its Application on Sheet Metal Stamping Processes

  Weilong Hu, Jeanne He - ETA-Engineering Technology Associates, Inc.

  Basic behaviors of anisotropic properties of materials, relating to sheet metal forming processes, are discussed. The R-value is used to describe some forming problems including wrinkles and thinning failures. According to the analysis results, to point out that the anisotropic behaviors of materials affect the formability of blanks in some cases is very serious. Finally, a numerical example is presented to discuss this property further.

• ANSA PRE PROCESSING FOR LS-DYNA

  Alexandros Kaloudis - BETA CAE Systems SA

• Ansys Forming® - The New GUI for Forming Simulations with LS-DYNA: An Overview and Outlook

  Chris Robinson, Pablo Hernandez Becerro, Kang Shen, Xinhai Zhu, Madhu Keshavamurthy, Volker Steininger

  We are motivated by being the engine behind human innovation that leads to more efficient manufacturing and digital engineering. As we lead out in providing world class simulation solutions, we provide an avenue for individuals and companies to develop products that can improve the quality of life across the globe, by enabling safer more efficient products to be brought to market at a lower overall cost and energy footprint in less time than using traditional methods. In short, digital engineering solutions help improve life, save the environment, and reduce costs.

• Application and CAE Simulation of Over Molded Short and Continuous Fiber Thermoplastic Composite

  Helga Kuhlmann, Pieter Volgers, Zhenyu Zhang (DuPont)

  In the field of structural design, from aerospace and automotive to consumer packaging, numerical structural analysis using the finite element method (FEM) is becoming ever more important to accurately predict the performance of the considered part. In a highly competitive market, industries are demanding higher performance, improvements in fuel efficiency, increased recycling and greater safety, whether this is an airplane wing or mineral water bottle. In response to the above factors, there has been a significant increase in the application of composites. Today, finite element simulations are used extensively in the design and assessment by virtually all mayor industries. Finite element analysis (FEA) has become an integrated tool in this design and optimization. In this paper, beams constructed from over molded Short fiber Reinforced Thermoplastic on Continuous Fiber Reinforced Thermoplastics are described. One of the challenges is accurate CAE simulation of the static and dynamic behavior of the part. Model data are validated through correlation between coupon and sub-system physical tests, and further verified with results from quasi-static and impact tests. Physical test on beams confirmed good correlation between test and Finite Element Analysis.

• Application and CAE Simulation of Over Molded Short and Continuous Fiber Thermoplastic Composites, Part I

  P. S. Kondapalli, K. Grumm (BASF Corp.)

  Short Fiber Reinforced Thermoplastics (SFRT) such as glass filled Polyamide 6 and 66 have been widely adopted as a metal replacement in a wide range of industries. The main advantage of using these materials is high strength to weight ratio, light weight, parts consolidation, easy manufacturability etc. Continuous Fiber Reinforced Thermoplastics (CFRT) are also gaining popularity because of its ability to achieve high directional stiffness/strength by tailoring the number of layers and angles. Applications which combine these two by over molding SFRT on CFRT inserts are still in its infancy. One of the hurdles is the lack of good CAE simulation capability for such applications. This paper describes the CAE tools that are developed using LS-DYNA to successfully model static and dynamic behavior of such parts. Material 58 in LS-DYNA is used for modeling the CFRT material while a User Defined Material Law models the SFRT material and they are coupled together through suitable contact definitions. Its applicability is verified through a number of examples varying from very simple to complex configurations

• Application and CAE Simulation of Over Molded Short and Continuous Fiber Thermoplastic Composites, Part II

  P. S. Kondapalli, K. Grumm (BASF Corp.), Y. Cao (Faurecia North America), V. Laurent (Faurecia Europe)

  Automotive seating back frames for front row are mostly constructed from high strength steel in order to meet very rigorous crash requirements. The main requirements are meeting the rear impact and luggage retention behavior as specified by the standards. In this paper, seating back frames constructed from over molded Short Fiber Reinforced Thermoplastics (SFRT) on Continuous Fiber Reinforced Thermoplastics (CFRT) inserts are described. One of the challenges is accurate CAE simulation of the static and dynamic behavior of such parts. CAE tools using LSDyna were developed to model accurately the rear crash and luggage retention behavior. Designs validated through CAE analyses were used to cut the tool and build prototype parts. Physical tests on Prototype parts confirmed good correlation between the tests and FEA. They met all the required criteria without requiring any design changes.

• Application of *MAT_258 for Bending and Crushing of Extruded Aluminum Profiles Using Shell Elements

  Jens Kristian Holmen, Joakim Johnsen (Enodo AS), David Morin, Tore Børvik, Magnus Langseth (Norwegian University of Science and Technology (NTNU))

  *MAT_258 (*MAT_NON_QUADRATIC_FAILURE) is a through-thickness failure regularization model for shells in LS-DYNA®. In this model the failure parameter is computed as a function of the size of the element as well as its bending-to-membrane loading ratio. The constitutive behavior and fracture surface in *MAT_258 are represented by well-known analytical expressions which simplify the calibration process. This means that ductile failure initiation can be predicted in thin-walled metallic structures with minimal calibration effort and cost. In this study, we go through the calibration process of *MAT_258 for two aluminum alloys before the calibrated material cards are applied in shell element simulations of double-chamber aluminum extrusions in both three-point bending and crushing.

• Application of a Composite Material Shell-Element Model in Ballistic Impact and Crush Simulations

  Tobias Achstetter, Kelly Carney, Paul Du Bois, Cing-Dao Kan (George Mason University), Sheng Dong (The Ohio State University), Allen Sheldon (Honda R&D Americas)

  A new orthotropic material model with tabulated hardening curves for different loading directions, strain-rate and temperature dependency, damage, and a new strain-based generalized tabulated failure criterion was utilized to simulate ballistic impacts and a C-channel under crush loading. These validation simulations of the material model were performed to test the physical usefulness and robustness of the developed material model. Ballistic impact tests were chosen to highlight the capabilities of the material model in high speed impact applications. For the tested unidirectional composite material in the ballistic impact, extensive material data was available. In a recent study, Dong et al. calibrated an existing material model in crush simulations to match force-displacement characteristics of several crush experiments and a match between tests and simulations was achieved after several rounds of optimization. To highlight the capabilities of the new material model in crush load cases, its results were compared to the force-time history obtained in tests and simulations using MAT58. For both the ballistic impact and crush simulations, the same modeling approach was used.

• Application of a Full-Field Calibration Concept for Parameter Identification of HS-Steel with LS-OPT®

  Christian Ilg, André Haufe, David Koch, Katharina Witowski, DYNAmore GmbH;, Nielen Stander, Livermore Software Technology Corporation;, Åke Svedin, DYNAmore Nordic;, Mathias Liewald, Institut für Umformtechnik, Universität Stuttgart

  In recent years results of digital image correlation (DIC) techniques have significantly improved in terms of accuracy, resolution as well as the speed of experimental strain measurement. The current availability of 2D or even 3D surface strain history during loading allows new approaches in constitutive parameter identification. In addition, localization (Fig 1.) exhibited in the numerical simulation can be integrated with DIC to identify constitutive parameters.

• Application of Crack Propagation Simulation of Windshield to Roof Strength Analysis

  R. Chikazawa, T. Komamura, S. Yamamoto, T. Yasuki, S. Kojima (Toyota Technical Dev. Corp.)

  This paper describes a new modeling method to represent the crack propagation of windshield, namely the laminated safety glass. In the roof strength analysis used for vehicle development process, it is not easy to accurately predict crack propagation paths with existing modeling method, e.g., improving material properties. If the windshield cracks in a test using a prototype vehicle, the body deformation in the simulation and that in the test might not match, resulting in a less accurate simulation of force transfer to vehicle frames through the windshield. Therefore, prediction of crack propagation in a windshield is significant in accurately estimating the deformation and improving the accuracy of roof strength simulation results. The new modeling method to represent the crack propagation of the windshield was applied using tied overlapping shell technique, one of the modeling methods for material fracture, which has been developed by Kojima et al. The tied overlapping shell technique consists of element groups made of base elements and overlapping elements which are rotated 45 degrees in the normal direction. The base and the overlapping elements are connected using tied contact. The physical laminated safety glass windshield is constructed by placing an adhesive polyvinyl butyral (PVB) interlayer between two glass panes, outer glass and inner glass. In this study, double overlapping shell parts and a PVB interlayer part were applied to a windshield model to represent the crack propagation of the glass. Consequently the model has three layers with five mesh plates. Each part is modeled with shell elements and positioned corresponding to the neutral location of each layer thickness respectively. Four-point bending tests using specimens cut out of windshield glass were carried out to determine the critical fracture strain of glass considering the loading mode in roof strength analysis. Thereafter, application of the windshield glass model developed in this study to a roof strength analysis model was carried out to validate against test data. This paper summarized the application of new modeling method to represent the crack propagation of windshield glass in a roof strength analysis. It was found that the first two cracks propagation and the maximum force of the roof strength could be simulated. In the model the first two cracks propagated in the same shape as seen in the test. However, the number of crack propagation paths observed in the simulation was just two while there were many crack paths observed in the test. In addition, the difference in the maximum force of the roof strength between in the simulation and in the test was approximately 1%. However, after the cracks occurred, the force dropped more rapidly in the simulation than in the test. With this consideration there may be room for correction of the elimination methods.

• Application of Digital Image Correlation to Material Parameter Identification using LS-OPT

  N.Stander (LSTC); K. Witowski, A. Haufe, M. Helbig, D.Koch, C. Ilg (DYNAmore)

  Digital Imaging Correlation (DIC) is an optical method which provides full-field displacement measurements for mechanical tests of materials and structures. It can be used to obtain temporal displacement, deformation or strain fields from an experimental coupon and can be combined with Finite Element Analysis to identify the constitutive properties of a material [1]. Because DIC-based parameter identification is an inverse process, optimization is used to obtain the parameters which will minimize the discrepancy between the measured and the computed fields. The Mean Squared Error functional typically used [1] is: f(x)=∑_(j=1)^n ‖φ_j (x)-φ ̃_j ‖^2 where φ_j (x) is a vector of nodal displacements/strains (for computation and experiment) at a number of observation points and n is the number of observation states. The functional can be augmented to incorporate global force-displacement measurements or any other functional resulting in parameter identification based on DIC. As part of this research, the DIC methodology was implemented in the LS-OPT® code utilizing the following main features: (i) multi-point responses and histories, (ii) the alignment and automatic mapping of points to an FE model. An graphical interface is provided for importing ARAMIS/GOM® (a popular commercial optical test package) test results. As a first test example, a parameter identification problem was constructed using a flat tensile bar with a hole in which the deformation field history was used as "test" input to recover the original parameters. Further parameter identification examples will be presented at the conference.

• Application of Dynamic Relaxation in Thermo-Elastic Structural Analysis of Highway Pavement Structures

  Samir N. Shoukry, Gergis W. William, Mourad Riad - West Virginia University

  This paper describes the application of the dynamic relaxation technique implemented in LS-DYNA in analyzing large transportation structures as dowel jointed concrete pavements under the effect of temperature variations. The main feature of the pavement model is the detailed modeling of dowel bars and their interfaces with the surrounding concrete using extremely fine mesh of solid elements, while in the bridge structure, it is the detailed modeling of the girder-deck interface as well as the bracing members between the girders. The 3DFE results were found to be in a good agreement with experimentally measured data obtained from instrumented pavements sections constructed in West Virginia. Thus, such a technique provides a good tool for analyzing the response of large structures to static loads in a fraction of the time required by traditional implicit finite element methods.

• Application of FEA in Stamping Auto Underbody Parts

  Yuyuan Wang, Marcel Pillon, Ron Ouellette, Chris Pitre, John Laporte - Canadian Engineering and Tool

  The complex auto underbody components need a long process of die design and tryout, some times need several to hundred times of costly trial-and-error to get required stamping parts. It is very critical to the die design how to decide and evaluate the die shapes of each forming stage and how to distribute the deformations between preform(s) and form for multi-stage forming. Combination of simulations for each forming stage using Dynaform and shape design using Catia can reduce the time and cost of die tryout, and make the die design optimization possible. The stampability of the part can be evaluated. The optimized die shapes and deformation distribution can be obtained. The main forming failures, such as wrinkles/double metals and cracks can be solved at die design stage. This paper attempts to show some applications of simulation techniques combined with shape design in the die design.

• Application of FSI/ALE on Mower Grass Cutting Simulation

  Vincent Zou, John Cox (Stanley Black & Decker)

  A mower’s grass mowing quality and energy consumption are two very important factors for battery powered mower development. The challenges include developing a highly efficient cutting blade that matches with the deck for creating the ideal air flow for bagging, mulching and side discharging and consumes as little energy as possible, which, improves the battery running time. It is critical for the development engineers to understand the mower’s air flow inside the deck, the blade’s energy consumption for air flow and clippings transportation during mowing. In this paper, the LS-DYNA® FSI/ALE was used to simulate the mower mowing process. The simulation model was validated, and the result was used for improving the mower’s deck and blade design.

• Application of LS-DYNA ® to NVH Solutions in the Automotive Industry

  Prasanna S. Kondapalli, Tyler Jankowiak (BASF Corp.), Yun Huang (LSTC Corp. Livermore)

  There are a number of powertrain applications in the Automotive Industry made of short glass fiber reinforced thermoplastics (Polyamide 6 or 66). Examples of these are Air Intake Manifolds, Cylinder Head Covers (CHC’s), Oil Pans etc. Assessment of NVH (Noise, Vibration & Harshness) characteristics using simulation tools is a critical requirement for such applications. Modal analysis, steady state dynamic analysis and acoustic analysis are some of the CAE (Computer Aided Engineering) analyses that are required. LSTC has developed a range of tools within LS-DYNA to carry out such analyses. In this paper, these capabilities are explored for various NVH analyses of automotive components. Examples of modal analysis and steady state dynamic response using the finite element method (FEM) are given and compared with other standard software. Boundary element methods (BEM) are well suited for doing acoustic analyses because of its requirement for modeling only the boundary of a vibrating body. Both the direct and the indirect boundary element methods are implemented in LS-DYNA. Examples using both methods are shown. Various options existing within these methods are also discussed. Post processing of acoustic quantities are demonstrated.

• Application of LS-DYNA and MADYMO Coupled Model for Simulating an Offset Frontal Crash Scenario

  Gunasekar T. J., Mostafa Rashidy - EASi Engineering, Norman Ludtke - Ludtke and Associates, Bruce Spinney - NHTSA

  A full vehicle finite element model of the 1995 Chevrolet Lumina validated in full frontal impact was used to simulate a frontal offset impact. The tibia index injury criteria set forth in the European Directive 96/79 were used to assess the injury indices of the occupant in frontal offset computer simulation. Based on the injury predictions from the baseline model, a structural modification to vehicle was made in order to reduce the tibia index. In the modified vehicle model simulation, the tibia index of the occupant was found to be reduced from 1.13 to 0.73 for the right tibia and from 0.62 to 0.45 for the left tibia.

• Application of LS-DYNA  in Structural Fatigue Analysis and Post-Processing with LS-PrePost 

  Yun Huang, Zhe Cui, Philip Ho, Chengju Zhang (LSTC)

  This paper provides a review of the development of LS-DYNA in structural fatigue analysis and the post-processing of the results with LS-PrePost. Fatigue is the progressive and localized structural damage that occurs when the material is subjected to cyclic loadings. Fatigue damage and failure are very common in industries. Some studies have suggested that over 80% of all mechanical failure of metal are attributable to fatigue. Starting from 971 R7 version of LS-DYNA, a series of features have been implemented in LS-DYNA to provide fatigue and durability analysis for metal structures, under various vibration loading conditions. The analysis provides accumulative damage ratio, expected fatigue life and cycles for the structures, based on the Palmgren-Miner rule and material’s S-N curve. With the recent updates in LS-PrePost (4.2, 4.3), a new interface has been added to provide the fringe plot of the fatigue variables, which greatly simplifies the post-processing of the results and makes the result analysis easier. Some examples are provided to demonstrate the effectiveness and convenience in running LS-DYNA and LS-PrePost for fatigue analysis and results post-processing.

• Application of LS-DYNA in Identifying Critical Stresses Around Dowel Bars

  Samir N. Shoukry, Gergis W. William, Mourad Riad - West Virginia University

  A detailed 3D Finite Element (3DFE) Model is developed to examine the triaxial state of contact stress that develops around the dowel bars due to both traffic and thermal loads. Dowel bars are modeled using 8-node solid brick elements. Sliding interfaces with friction that permit separation are modeled along the full cylindrical surface between each dowel and the surrounding concrete. The model results are validated through comparison with laboratory measured strains in dowel jointed concrete specimens. The model results reveal that under the standard axle load, tensile stresses of magnitude sufficient to initiate localized concrete failure may develop in the concrete surrounding the loaded dowel. Such stresses are responsible for initiating cracks in the concrete that lead to the rapid joint deterioration.

• APPLICATION OF LS-DYNA IN NUMERICAL ANALYSIS OF VEHICLE TRAJECTORIES

  Jerry W. Wekezer - FAMU-FSU College of Engineering, Krzysztof Cichocki - Technical University of Koszalin

  Errant vehicles may pose a serious threat to neighboring traffic of pedestrians, bicyclists, and even to their drivers in a densely populated urban environment. Accident reconstructions have indicated that street curbs do not offer any meaningful protection against errant vehicles, which can easily traverse street curbs even at small velocity and shallow angles. The paper presents research results of a study, in which computational mechanics was utilized to predict vehicle trajectories upon traversing standard Florida DOT street curbs. Computational analysis was performed using LS- DYNA computer code and two public domain, finite element models of motor vehicles: Ford Festiva and Ford Taurus. The suspension systems of the original vehicle models were evaluated and additional suspension components were identified and developed. The finite element models of the required suspension systems were developed using geometry from the actual suspension parts, captured using a digitizing arm. Due to complex geometry of these parts, the MSC-PATRAN preprocessor was used to create data for LS-DYNA code. Shock absorbers were modeled using discrete spring and damper elements. Connections for the modified suspension systems were carefully designed to assure proper range of motion for the suspension models. Inertia properties of the actual vehicles were collected using tilt-table tests and were used for LS-DYNA vehicle models. A standard FDOT street curb model was developed using rigid wall option in LS-DYNA. Initial, computational mechanics analyses suggest that vehicles tend to retain larger amount of their kinetic energy after traversing street curbs. It is therefore dangerous to anticipate that performance of street curbs would be comparable with that demonstrated by guardrails. In order to validate the assumed discrete numerical models and the results of LS-DYNA analyses, full-scale experimental tests have been performed at Texas Transportation Institute. Two types of vehicles have been tested: Ford Festiva and Ford Taurus, both for two values of approach angle: 15 and 90 degrees, with impact velocity of 45 mph. Experimental results including accelerations, displacements and overall vehicles behavior were registered by high-speed video cameras and have been compared with numerical results and computer animations. Verification results indicated a good correlation between computational analysis and full-scale test data. The study also indicated a strong importance of properly modeled suspension and tires on resulting vehicle trajectories. The major goal of the research was to study the behavior of various vehicles (from small Ford Festiva to pickup truck Chevrolet C2500), for different approach angles, velocities and curb profiles. Experiences gained in preliminary numerical analyses and experimental tests allow studying a matrix of critical cases without time- consuming and costly additional experimental testing.

• Application of LS-DYNA SPH Formulation to Model Semi- Solid Metal Casting

  F. Pineau, G. D’Amours - National Research Council Canada, Aluminium Technology Centre

  Semisolid metal alloys have a special microstructure of globular grains suspended in a liquid metal matrix. This particular physical state of the matter can be exploited to produce near-net-shape parts with improved mechanical properties. Indeed, semi-solid processes take advantage of a much higher apparent viscosity of the die cast materials by limiting the risk of oxide formed on the free surfaces to become incorporated into the casting when the material is injected into the die. Semi-solid processes that use billets as feedstock material are however tied up with an additional type of surface contamination. During the injection phase, the external-skin on the periphery of the billet, which has been in contact with air and lubricant during the transfer in the shot sleeve may be incorporated into the casting. This can be an important cause of reject for most structural parts in the automotive industry. In order to predict and control the occurrence of skin inclusion into cast parts during the injection phase of semi- solid processes, Lagrangian methods are appropriate. Indeed, the skin, composed of contaminated or even partially solidified metal, has different mechanical properties compared to the core of semi-solid aluminum. Abitrary- Lagrangian-Eulerian formulations, which can account for the coupling between the “solid” skin and the flow of “semi-solid” aluminum are promising but still necessitate a huge amount of computer power. On the other hand, particle based Smoothed Particle Hydrodynamics (SPH) approaches are particularly well suited to this kind of flows involving complex flow behavior and solidification. These methods are able to track accurately free surface flows with fragmentation and break up as well as to follow the advection of oxides through the flow. In this paper, a first analysis is performed in order to investigate the potential of the SPH solver of LS-DYNA to deal with the problem of skin inclusion in semi-solid die casting processes. Preliminary results show that the SPH approach is a very promising simulation tool to follow the skins during semi-solid injection casting.

• Application of LS-DYNA for Auto NVH Problems

  Yun Huang, Zhe Cui (LSTC)

  NVH (Noise, Vibration and Harshness) is an important topic for the design and research of automotives. Increasing demands for improved NVH performance in automotives have motivated the development of frequency domain vibration and acoustic solvers in LS-DYNA. This paper presents a brief introduction of the recently developed frequency domain vibration and acoustic solvers in LS-DYNA, and the application of these solvers in auto NVH problems. Some examples are given to illustrate the applications.

• Application of Machine Learning technique to incorporate manufacturing and Testing variation for Robust BIW design for Crash performance

  Shinoj Narayan Nair, Yoshinori Sugimoto, Susheel Khanna, Kei Nagasaka

  In vehicle development CAE plays crucial role in arriving at optimum structural design to meet various vehicle performance targets in different domain such as Crash, NVH, Durability etc. Accurate CAE methodology can aid in reducing the number of physical tests & reducing overall vehicle development time. However, there are instances where there are gaps observed between test results and CAE predictions. These gaps get amplified in crash simulations as the event is highly dynamic and non-linear behavior simulation is always challenging. In order to enhance CAE methodology, it was decided to incorporate the effect of manufacturing and testing variations in crash CAE simulations. Manufacturing process accounts for variations due to inherent variation in material properties, spot weld nugget diameter, manufacturing processes such as stamping etc. whereas Physical Testing houses variation in barrier positions, test speed etc. within specified tolerance defined by regulatory bodies. These variations affect structural performance and negating these issues in early design phase will help to arrive at robust structural design.

• Application of MADYMO Occupant Models in LS-DYNA/MADYMO Coupling

  Happee R., Janssen, A.J., Fraterman E., Monster J.W. - TNO Automotive

  The LS-DYNA – MADYMO coupling has been extended so that users gain maximal flexibility in their choice of software and models. Where the traditional coupling allowed only MADYMO ellipsoids and planes to contact entities in the coupled code, now contact can also be defined with MADYMO FE. This enables state of the art MADYMO dummy models, subsystem models, barrier models and human models to be applied in the coupling with LS-DYNA.

• Application of Model Order reduction Techniques in LS-DYNA

  P. Friedrich (SCALE)

• Application of New Concrete Model to Roadside Safety Barriers

  Akram Abu-Odeh - Texas Transportation Institute

  The subject of roadside safety has been seeing a healthy growth in the use of nonlinear finite element analysis in designing and analyzing roadside hardware systems. Some factors that helped researchers include the expanded capabilities of LS-DYNA commercial finite element code, the availability of several public domain vehicle models and the availability of material models explicitly built and modified for roadside safety applications. One of these new material models is *MAT_CSCM (and the short input version *MAT_CSCM_CONCRETE) incorporated in LS- DYNA version 971 as material type 159. Material model *MAT_CSCM which was developed by APTEK INC. is a continuous surface cap material model with the ability of capturing concrete material behavior using minimal input like the compressive strength of concrete and maximum aggregate size. In this paper two examples of using LS- DYNA to simulate impacts with concrete barrier are presented. They are two different pendulum simulations of a concrete parapet with a steel railing on top. The deformation and damage profiles along with the force time history were used as measures for comparing tests and simulations. Both examples indicate a reasonable correlation between tests and simulations. Figure 1a shows the response of the concrete parapet as tested and figure 1b shows the response calculated from the LS-DYNA simulation.

• APPLICATION OF NON-DETERMINISTIC METHODS TO ASSESS MODELLING UNCERTAINTIES FOR REINFORCED CARBON-CARBON DEBRIS IMPACTS

  K. Lyle - NASA Langley Research Center, Hampton VA, E. Fasanella - ARL-VTD Langley Research Center, Hampton VA, M. Melis and K. Carney- NASA Glenn Research Center, Cleveland OH, J. Gabrys -The Boeing Company, Philadelphia PA

  The Space Shuttle Columbia Accident Investigation Board (CAIB) made several recommendations for improving the NASA Space Shuttle Program. An extensive experimental and analytical program has been developed to address two recommendations related to structural impact analysis. The objective of the present work is to demonstrate the application of probabilistic analysis to assess the effect of uncertainties on debris impacts on Space Shuttle Reinforced Carbon-Carbon (RCC) panels. The probabilistic analysis is used to identify the material modeling parameters controlling the uncertainty. A comparison of the finite element results with limited experimental data provided confidence that the simulations were adequately representing the global response of the material. Five input parameters were identified as significantly controlling the response.

• Application of Scrap Shedding Simulation in Stamping Manufacturing

  Diane Xu - Ford Motor Company, Jim Kosek - Engineering Technology Associates, Inc.

  One of the most critical issues in stamping manufacturing today is the successful shedding of scrap from limited trim dies. Until recently, die tryout was the first opportunity to check the shed scrap feasibility of a trim die. The newly developed scrap shed analytical module can be used for analyzing trim die scrap shed feasibility before die creation. It simulates Scrap shedding during or after the die is designed using Dynaform and LS-DYNA®. Scrap shedding simulation offers die designers and manufacturers the opportunity to closely examine a trim die’s performance before die construction. With today’s tighter die design timelines and reduced number of dies in manufacturing, it is more critical than ever to establish trim die design integrity as early as possible in the design process. This can be achieved through Dynaform scrap shedding simulation. Dynaform scrap shedding uses a flexible body approach to simulate the exiting of scrap from the workstation. This allows for full interaction of all essential variables and forces acting on the die and sheet metal part. It allows for a real world simulation that calculates the effect of any changes in die speed, initial velocity, material properties or die design. Various trim operations, such as direct and cam trim, can be very easily simulated. Once a design defect is found, possible solutions can also undergo a virtual tryout in the Scrap Shedding simulation. It has a great impact on cost and timing when used in stamping engineering, and can be used to avoid the pitfalls of defective die design.

• Application of Shell Honeycomb Model to IIHS MDB Model

  Shigeki Kojima - TOYOTA TECHNICAL DEVELOPMENT CORPORATION, Tsuyoshi Yasuki, Koji Oono - Toyota Motor Corporation

  This paper describes a new finite element modeling method of Aluminum honeycomb using shell elements. It is our new modeling method that cell size of honeycomb structure is enlarged to increase time step size for FEM analysis, and compressive strength is controlled by thickness of shell elements. New modeling method was applied to IIHS moving deformable barrier model, and side impact analysis with a full vehicle model was performed. The result of simulation using a new barrier model showed much better correlation with a test result than previous simulations.

• Application of SynfiniWay Grid Platform for iterative LS-DYNA studies

  E. Deguemp - Fujitsu Systems Europe, M. Adoum, V. Lapoujade - CRIL Technology

  Whether end-users need to access local or remote systems, to use a batch system or to run jobs interactively, they will always raise the same questions: “Which system can I run my job on?” and “How do I get data to the machine where my job will execute?” Users should only need to know what applications they want to run and where the inputs for these applications are located. To answer these needs, Fujitsu markets a middleware product called SynfiniWay which hides all issues related to CPU location, and allows execution of complex applications via workflows. The conclusion of this paper is that the SynfiniWay middleware can solve LS- DYNA iterative problems: the search for an optimal mesh size or successive LS- DYNA calculations with modified initial conditions. SynfiniWay provides an infrastructure to execute these studies automatically and transparently on remote computers (grid computing).

• Application of the Discrete Elements Method to Frequency Analysis and Use of the “Bond” Method for Fracture Modeling

  Tess Legaud, Edith Grippon,Vincent Lapoujade (DynaS+), ierre-Louis Chiambaretto, Yves Gourinat (Université de Toulouse)

  Nowadays more and more complex mechanical behaviors have to be modelled. In order to do so, the generally used numerical methods, like finite elements, show some limitations. Particularly, finite elements’ ability to model granular media is reduced, partly because of the contact handling complexity between each grain. One of the alternatives is to use meshless methods. Within the software LS-DYNA ® , there notably exists a meshless method named “Discrete Element Method” (DEM). This method was initially implemented in the software to model granular media, and especially granular flows, where the displacements of each particle are deduced from Newton’s equation [1]. An extension of the method consisting in bonding particles together with smooth heterogeneous bonds essentially permits to model fracture (DEM-HBOND), which is a significant issue in many fields. Our studies consist in two disconnected projects presented below: As part of the Midi-Pyrénée project “TANKYOU”, we are trying to find a granular material that would have the same vibratory behavior as a fluid. In order to do that, we have especially been seeking the mode shapes of a cylinder fully filled with Discrete Element Spheres (DES). The issue here is to vibrate DES with explicit calculations. As part of an internship, a tensile test on a DES steel specimen has been performed to test fracture modeling. The impact of particles’ organizations (meshes) in the specimen has been studied, and results have been compared with finite elements results.

• Application of the ISPG Method in Various Manufacturing Processes Simulation

  Li Zhang, Xiaofei Pan, Tung-Huan Su, Jingxiao Xu, C.T. Wu, Philip Ho

  The Incompressible Smooth Particle Galerkin (ISPG) theory was proposed by the R&D team Computational and Multi-scale Mechanics Group (CMMG) at LSTC in 2017 [1]. It developed a new Incompressible Navier-Stokes solver to model free-surface Newtonian and Non-Newtonian fluid flow with surface tension and adhesion force. The Lagrangian particle method was employed to discretize the ISPG part to approximate the Navier-Stokes equation, coupled with surrounding rigid structures. The ISPG method is fully implicit, and in its dynamic mode, it simulates in real time fluid behaviors in many manufacturing processes. The ISPG’s robust, in-core, and smart mesh adaptivity allows fluid flow in complex geometry, accurately capturing and aligning the ISPG surfaces with the structure surfaces while keeping the model size down. It also allows for separation and fusion within the ISPG fluid. The ISPG advanced material models allow for the simulation of fluid behavior with various viscosities from liquid to near solid state.

• Application of the MAT 213 Composite Impact Model to NASA Problems of Interest

  Robert K. Goldberg, Trenton M. Ricks, Troy Lyons, Javier Buenrostro, Jacob Putnam, Daniel Slaughter

  As composite materials are gaining increased use in aircraft components where impact resistance under high-energy impact conditions is important (such as the turbine engine fan case), the need for accurate material models to simulate the deformation, damage, and failure response of polymer matrix composites under impact conditions is becoming more critical.

• Application of the SPH Finite Element Method to Evaluate Pipeline Response to Slope Instability and Landslides

  A. Fredj, A. Dinovitzer (BMT Fleet Tech-nology), M. Sen (Enbridge Pipelines)

  Buried pipelines operating on active slopes can be subject to lateral and axial loads resulting from slope instability and landslides. The techniques to predict pipeline displacements, loads, stress or strains are not well described in design standards or codes of practice. Finite element analysis based soil-pipe interaction simulation has developed in recent years and is proving to be a useful tool in evaluating the pipeline behavior in response to slope movement. A description of the BMT pipe soil interaction modeling techniques, their validation against full scale trails and comparison to spring support models has been previously published.

• Application of the SPH Method for Simulation of Aerospace Structures under Impact Loading

  M-A Lavoie, A. Gakwaya1 - Laval University, Cité Universitaire, Quebec, Canada, M. Nejad Ensan - National Research Council, Ottawa, Ont. Canada.

  The SPH method is applied in industrial level problems as encountered for example in studies related to bird impact on composite aircraft structures. This paper first demonstrates the accuracy of the method for bird impact on rigid target modeling and then applies the developed model to a more complex problem, namely the secondary bird impact.

• Application of Topology Optimization for Crash with LS-OPT/Topology

  Heiner Müllerschön, Katharina Witowski - DYNAmore GmbH, Nikolay Lazarov - University of Karlsruhe

  Since end of 2009 a new software tool LS-OPT/Topology is available from LSTC. With LS-OPT/Topology nonlinear topology optimization with LS-DYNA can be applied for static and even for dynamic problems. The underlying method is Hybrid Cellular Automata (HCA) which is a heuristic, gradient-free approach. The objective is to obtain a structure with uniform internal energy density subject to a given mass fraction. In the current version LS- OPT/Topology-1.0, topology optimization with hexahedron solid elements, material *MAT_024 and some established contacts is possible for single and for multiple load cases. In this paper, first experience with the HCA-methodology and the application of LS-OPT/Topology to industrial problems is demonstrated. Capabilities and limitations of the new implementation will be highlighted.

• Application of Trimmed Solid in Isogeometric Analysis to Aluminum Diecast Part

  Tadashi Naito, Shinnosuke Nishi, Takafumi Ohya

  With the changes in the global environment such as global warming, automobile OEMs and their affiliates have an urgent need to address carbon neutrality and resource circulation to reduce the environmental impact of their products and their corporate activities. Under such circumstances, as part of the effective use of materials, companies are considering the adoption of large aluminum diecast (ALDC) parts aimed at weight reduction through part integration, and enhancement of material recycling rates. Some OEMs have already introduced such parts to the market. Since prototyping and testing of large ALDC parts require enormous costs and time, it is important to be able to predict and evaluate the part performance through simulations. Crash calculations are no exception.

• Applications of ICFD / SPH Solvers by LS-DYNA to Solve Water Splashing Impact to Automobile Body

  G. Wang, E. DeHoff (Honda); F. Del Pin, I. Caldichoury, E. Yreux (LSTC); K. Gardner (Ohio State University)

  When a vehicle runs at high speed on a watery or muddy road, the high speed splashing generated by tire rotation often causes damage to the underbody panels. This is a challenging dynamic FSI (fluid-structure interaction) problem for Honda to consider. ICFD and SPH are two powerful solutions used in FSI applications, especially for high speed flow and with dynamic free surface evolution. This paper presents some FSI solutions of water splashing of automotive components by using ICFD and SPH solvers from LS-Dyna.

• Applications of ICFD solver by LS-DYNA in Automotive Fields to Solve Fluid-Solid-Interaction (FSI) Problems

  G. Wang, P. Rodriguez, J. Tippie, S. Smith (Honda R&D Americas); F. Del Pin, I. Caldichoury (LSTC)

  Fluid-solid interaction (FSI) becomes a more and more important and wider application field in the automotive industry. It is challenging to CAE engineers to predict performance of complicated systems under high speed flow and with dynamic free surface evolution. This paper presents the three following FSI accomplishments in the power sports field by using ICFD solver from LS-DYNA®.

• Applications of LS-DYNA in Electronics Products

  Hanks Hsu, Brian Hsiao - Flotrend Corporation

  Portable electronic devices have become smaller and lighter but they are also easily damaged during accidentally drop situation. Therefore, new electronic products are usually needed to pass requirements of shock and drop test before actually delivering to customers. FEM simulation provides engineers a useful and powerful approach to identify the potential weakness of products before the prototype is even made. The report will introduce the applications of the Ls-dyna in a virtual lab which simulates the experiment conditions of shock and drop tests in computers. It also shows Ls-dyna can be a very effective tool for engineers to improve the performance of their design in the shock and drop test.

• APPLICATIONS OF LS-DYNA TO STRUCTURAL PROBLEMS RELATED TO RECOVERY SYSTEMS AND OTHER FABRIC STRUCTURES

  Benjamin A. Tutt, Anthony P. Taylor - Irvin Aerospace Inc.

  Irvin Aerospace Inc., has used the LS-DYNA Explicit Finite Element Analysis (FEA) tool for over five years for the analysis of static and dynamic fabric problems. The References provide many examples of this previous work. Our first application was the analysis of airbag landings for several spacecraft programs, including Reusable Launch Vehicles (RLV’s), various Unmanned Air Vehicles (UAV’s), Military Airdrop Systems, and planetary exploration systems. These are all covered in the references. This paper presents some current results along the lines of the above, and other recent developments. These include an air beam supported structure, which was evaluated for both snow and wind loads, and a fabric blanket system that was somewhat optimized by a combination of FEA analysis and testing. While these applications appear rather bland, the air beam structure is designed to house military fighter and rotary aircraft and must withstand significant snow and wind loads. The blanket system is used to constrain a target-missile that performs a unique ‘Air Launch’ mission, involving extracting the target from a cargo aircraft and allowing it to stabilize prior to release and ignition.

• Applications of Multiscale and Subcycling methods for Press Hardened Steel Parts Failure Assessment

  Y. Drouadaine (ArcelorMittal)

  Press Hardened Steel (PHS) parts, like B-pillar made of Usibor® 1500, are today the best steel solutions in order to fulfil the most aggressive crash requirements with the lowest body structure mass. However, these severe crash conditions request a failure risks analysis during the vehicle design process. The usual Usibor® 1500 failure modelling method proposed by ArcelorMittal always remains compatible with a current full car model mesh size, whether for base metal or spot-weld Heat Affected Zone (HAZ) or laser welded line. Shell elements in the mesh size range 3 mm – 5 mm are used with CrachFEM fracture criterion. One alternative, for an improved failure risk prediction, would be to use a meso-scale model with solid element mesh size less than 0.5 mm for the most critical areas. This method leads to a heterogeneous model when used in a full car crash simulation (finest 3D elements to 2D elements mesh size ratio close to 10 times). In this case, the time step is imposed to the whole model by the smallest elements. This may lead either to increase drastically the CPU time or to provide results affected by an excessive added mass level in case of a too ambitious imposed time step. LSTC and DYNAmore have recently developed (2014) new features like Subcycling - *CONTROL_SUBCYCLE_K_L - and Multiscale - *CONTROL_SUBCYCLE_MASS_SCALED_PART_{SET} - in order to reduce the calculation time without adding a huge amount of mass. It seemed interesting to use these new features in the field of heterogeneous crash models without none of the two time-step issues previously mentioned. The present paper will describe results obtained by these new features, especially the multiscale option. It is applied to different mesh size heterogeneous models, from a three points bending test on a specimen till a full car model during side impact. Energy balance stability, parts deformation, local plastic strain will be presented and compared with the ones obtained by the unique time-step reference calculation. A CPU time performances comparison will be also presented and then, the multiscale method efficiency will be established for each tested model. The elapsed time saving reaches 34% in case of a 3D local failure analysis performed on a full vehicle during side impact, without any negative impact on the quality of results. Current limitations of heterogeneous models, questions and expectations regarding the multiscale approach and the 3D-2D transition modelling will be also discussed to conclude the presentation.

• Applications of the new magnetostatic solver/ AMS preconditioner in LS-DYNA®

  M. Duhovic (TU Kaiserslautern), I. Caldichoury, P. L’Eplattenier, T. Nguyen (Ansys/LST), J. Hausmann (TU Kaiserslautern), L. Kielhorn, T. Rüberg, J. Zechner (Tailsit)

  Previous implementations of LS-DYNA’s EM module have relied on an explicit scheme, requiring very small time-step sizes and therefore long simulation times. Recently, a new magnetostatic solver/ AMS preconditioner has been developed in LS-DYNA®. Unlike the current implementation, the new solver is unconditionally stable with respect to the time-step size and allows for the handling of materials with high permeability and low electrical conductivity. In this paper, the capabilities of the new solver is tested on the use-case of carbon fiber reinforced thermoplastic composite (CFRTPC) laminate induction heating using magnetic flux concentrators/field formers. In the current work, induction heating characterization experiments were performed on carbon fiber poly(ether ether ketone) (CF/PEEK) laminates using two different coil geometries.

• Applying Buried Mine Blast Loads to a Structure Utilizing the User Module Capability

  E. Lazerson, H. Raz, Z. Asaf (Plasan SASA)

  Developing armored vehicles to withstand a buried mine blast is a challenging task. The development of solution with optimum trade-off between mobility and survivability cannot be done by trial and error alone. The development of reliable CAE model of the vehicle and threat, using a simulative tool, is essential. In the early design phase, extensive use of simulation is done to optimize the structure. This process requires a short turnover time for the simulations. Use of ALE or Particle Blast can give good results but involves long runtimes. On the other hand, using Load Blast (ConWep) or Initial Impulse Mine is fast and simple. Initial Impulse Mine works by applying initial velocity on selected elements. The unselected elements have initially zero velocity. This velocity discontinuity can lead to unreasonable results. The aim of the Load Blast is to simulate an air blast but not buried mines. It is possible to calibrate Load Blast to get the correct peak pressure or the local impulse, but not both. It is impossible to change Load Blast spatial pressure distribution. In this work a new user-defined module was implemented. This ConWep-like user loading enables the simulation of a buried mine explosion by modification of pressure distribution via a shape function. Using this technique a better pressure and momentum distribution over the target can be achieved with running times similar to *LOAD_BLAST_ENHANCED (ConWep). The new module is implemented in FORTRAN and activated using the *USER_LOAD_SEGMENT keyword. The compiled module is activated in the LS-DYNA® deck by using the new *MODULE_LOAD keyword. The use of the new solvers with dynamic loading of modules enables our simulation team members to use this code easily and to issue new versions of the module as needed.

• Applying Digital Image Correlation Methods to SAMP-1 Characterization

  Hubert Lobo, Brian Croop, Dan Roy (DatapointLabs, USA)

  SAMP-1 is a complex material model designed to capture non-Mises yield and localization behavior in plastics. To perform well, it is highly dependent on accurate post-yield material data. A number of assumptions and approximations are currently used to translate measured stress-strain data into the material parameters related to these inputs. In this paper, we look at the use of direct localized strain measurements using digital image correlation (DIC) as a way to more directly extract the required data needed for SAMP-1

• Applying the Dynamic Relaxation Step to Determine Influence on Global Model Response from Shock Tube Loading for Mounted Hybrid III Head Neck Assembly

  Emily Ward, Tim Harrigan - The Johns Hopkins University

  Blast-induced traumatic brain injury (bTBI) is a critical issue for warfighter protection. Since bTBI has many features in common with injuries due to impact loading, the Hybrid III crash test dummy can be used to study many aspects of this injury, and the head-neck assembly of the Hybrid III dummy can provide a relevant initial bench test for computational studies of traumatic brain injury. LS-DYNA® has provided finite element models (FEM) of various Anthropomorphic Test Dummies (ATDs), and in this study the head-neck subassembly from the LSTC- NCAC 50th% Full FE H-III Dummy was used. To study the effects of blast on the head a shock tube experiment was simulated and the relevant loading conditions were applied to the head-neck assembly of the Hybrid III dummy FEM. The results were then compared to similar experimental test data. Since the initial tension in the neck cable of the Hybrid-III head-neck assembly is a key factor in the experimental response, simulating the initial tension in the neck cable is required in order to maintain a consistent boundary condition for the model. The neck cable definition in the Hybrid-III FEM was modified to include an initial stress, which was implemented using a dynamic relaxation step applied to initialize the model. The dynamic relaxation step is applied using explicit techniques and a sensitivity study is explored to understand impact of the initialization on the global response. The relative influence on the resulting global behavior response depends on the loading conditions.

• Approach for Modelling Thermoplastic Generative Designed Parts

  F. Althammer (Daimler/University of Stuttgart), D. Moncayo (Daimler), Prof. P. Middendorf (University of Stuttgart)

  This study presents an approach to characterize thermoplastic generative designed parts and compares the usability of different material models in LS-DYNA. For using 3D printed parts in prototypes it is at first necessary to be able to predict the deformation behaviour of the printed part itself. The deformation behaviour of thermoplastics and especially of thermoplastic generated parts depends on a variety of material properties. In general the parts have a composed anisotropy consisting of the process and material anisotropy. The process anisotropy is reflected to different mechanical properties due to the building directions of the 3D printer. The material anisotropy includes divergent tension and compression behaviour and approximately orthotropic behaviour due to particle reinforcement. The main task therefore is to evaluate current material routines and modeling techniques to ensure the predictability of the parts behaviour with available and implemented material cards. The performed characterization consists standard specimen tests for a non-reinforced and a carbon particle reinforced thermoplastic, which is produced in the selective laser sinter process. The conducted tests are a tensile, a compression and a shear test. The test specimen were built in different construction directions. In addition, component tests were executed in order to evaluate the predictability of the generated material cards in multiaxial stress states.

• Armor Steel Impacted by Projectiles with Different Nose Shapes – Numerical Modelling

  T. Fras, N. Faderl (French-German Research Institute of Saint-Louis), C. C. Roth, D. Mohr (ETH Zurich)

  The presented experimental investigation concerns 3 mm thick target plates impacted by strikers with different noses at velocity close to 300 m/s and is conducted to gain an insight into mechanisms of deformation and fracture characteristic for a high strength high hardness armour steel, [1]. Guaranteed by the producer yield strength and ultimate tensile strength of the steel are 1300 MPa and 2200 MPa, and the hardness is within 600 – 640 HB, [2]. Due to impacts, the projectiles and targets, both extracted from the armour steel, are severely deformed and fractured. Numerical simulations of the performed test are carried out using the explicit solver of the finite element software package LS-Dyna R9.0.1. The model used in the simulation implemented through the user material subroutine accounts for a yield function with a non-associated flow rule, a Swift–Voce strain hardening law and Johnson–Cook type of multipliers with the effects of strain rate and temperature. The stress-triaxiality, Lode angle parameter and strain-rate dependent Hosford–Coulomb fracture initiation model is employed to predict a steel failure, [3-4].

• ASPECTS OF SEAT BELT MATERIAL SIMULATION

  C. Pedrazzi, K. Elsäßer, S. Schaub - TRW Occupant Restraint Systems GmbH & Co. KG

  The so-called D-ring dynamic overturning is an instability phenomenon occurring occasionally during car crashes. It can have a negative effect to the restraint function of the seat belt system and lead to increased seat belt forces to the occupant. In order to avoid this phenomenon the influence of different parameters has to be investigated. Therefore a simulation model has been created, using the Finite Element Code LS-DYNA 3D. Major questions to be clarified in this context are: • Define initial geometry for the belt running through the D-ring. • Choice of appropriate material model. • Influence of physical parameters, i.e. D-ring geometry, friction properties, belt material, belt forces, crash pulse, etc. The definition of the initial geometry and a feasibility study have been presented at the 2000 CAD-FEM conference [2]. The modelling method, results for a given baseline geometry, variations in different material models and the pre-simulation of a new concept of the D-ring, the so called “roller D-ring” are presented in the current paper.

• Assembly of full-vehicle digital crash models using ANSA techniques

  A. Kaloudis (BETA CAE Systems)

  The level of complexity of the full-vehicle digital crash models varies between car manufacturers. Undoubtedly, however, it is very high and the trend is to become higher and higher, due to the fact that the development teams want their models to include even more details. During all these years a standard technique, that has become of common use, is the fragmentation of the full-vehicle model into *INCLUDE files. Each one contains a distinct physical subassembly of the vehicle, which we shall subsequently name module. This technique offers various advantages, but definitely sets a challenging task. That of connecting the modules to each other and assembling them into a full-vehicle model. Using the embedded capabilities of ANSA we have created processes and tools that enable : i) fast and robust intermodular connections represented by various element types, ii) efficient and reliable integrity check of these connections, iii) the assembly of multi-variant modules, iv) inspection of the connection areas in a lightweight view, v) an error-free update of modules’ versions, vi) the overview of the modules participating in the full-vehicle models with aid of graphs, vii) the reusability of already existing models, as the basis for the creation of new ones.

• Assessing and Validating the Crash Behavior of Securalex®HS, a High-Strength Crashworthy Aluminum Alloy, Using the GISSMO Model

  Callum J. Corbett, Laurent Laszczyk, Olivier Rebuffet (Constellium Technology Center)

  Specialized aluminum alloys play an ever increasing role in today’s automotive industry. The desire for lightweighting is driven by both performance aspects as well as the legislative framework regarding emissions and fuel efficiency. Using aluminum rolled products for structural car body parts requires good formability and high mechanical properties paired with predictable and safe performance under crash loading. Simulating and predicting the crash behavior requires a detailed material model including damage and failure. To this extent, a vast range of experiments are performed on Securalex ® HS samples. The relevant state of the material is the in-service temper, so that a heat treatment is applied to all samples prior to testing. In order to compare the simulation results to the experiments, digital image correlation techniques are used to measure strains on the specimen surfaces during testing. After calibrating the plastic material response, a detailed failure model is required. Using the GISSMO model, an equivalent plastic strain to failure curve depending on stress triaxiality is defined. It is parametrized with three variables and coupled with an optimizer based on the simplex method. By defining suitable error functions based on the simulation results, it is possible to optimize the failure curve and obtain a good correlation with the experiments. The final step lies in validating the failure model. To this end, the calibrated model is used to simulate and predict the deformation and crack initiation during the quasi-static axial crush of a square profile. The results are compared to experiments done on two-piece friction-stir welded boxes.

• Assessing Options for Improving Roadside Barrier Crashworthiness

  D. Marzougui, C.D. Kan, K.S. Opiela (George Mason University)

  The introduction of new crash test requirements raises questions about the efficacy of commonly used barriers that had been accepted under earlier test requirements. Seven commonly-used barriers were crash tested under the new MASH requirements in a recent NCHRP project. Three of the barriers tested did not meet the new requirements for the test with the 2270 kg vehicle. While the implementation of the MASH standards does not require hardware that passed the previous NCHRP 350 requirements to be re-evaluated, there is an interest in knowing whether these devices can be modified to meet the more stringent MASH requirements by DOTs. In another effort, these seven NCHRP crash tests were successfully simulated to provide an extended validation of the new finite element model of a Chevrolet Silverado pick-up truck as a surrogate for the 2270 kg test vehicle. This provided the opportunity to, among other things, evaluate the potential of various retrofit options for improving two of the three barriers that failed. An analyses of six modifications for the G9 Thrie-beam barrier and three variations of the G4(1S) guardrail median barrier was undertaken. A summary of the testing and simulation modeling of the two tests is presented as the basis for the simulation of modified versions of the barriers. The evaluation results are presented for each of the retrofit options and recommendations offered.

• Assessing the Convergence Properties of NSGA-II for Direct Crashworthiness Optimization

  Guangye Li - IBM Deep Computing Group, Houston TX, Tushar Goel, Nielen Stander - Livermore Software Technology Corporation

  The elitist non-dominated sorting genetic algorithm (NSGA-II) converges to the Pareto optimal front (POF) if a sufficient number of function evaluations are allowed. However, for expensive problems involving crash simulations, only a limited number of simulations might be affordable. It is observed that initially there are significant advances towards the POF but as the population matures, the improvements are relatively small. This means that one can probably limit the computational expense by terminating the search at the right point. The paper also demonstrates a successful use of IBM cluster for parallel processing that significantly reduces clock time for optimization.

• Assessment of Abdominal and Skeletal loadings and Kinematics during Frontal Impacts through a Novel Tool for HBM Variants Generation Based on the Occupant’s BMI

  Zouzias D, Fokylidis A, Lioras A, Rorris L

  HBM variant generation tools are solely based on morphing techniques to adjust the shape of the external surface to a target depending on the BMI of interest. Even though this approach can quickly produce HBM variants, downgrades the model’s mesh by stretching the elements and compromising their quality. Furthermore, the dependence of the abdominal organs morphology on the occupant’s BMI is rarely, taken into account. This paper presents a novel tool for automatic HBM variant generation, that respects elements’ quality taking also into account the volume of the abdominal organs.

• Assessment of Automotive Panel to Meet Handling Load Requirements: CAE Simulation

  Harihar Kulkarni, John M. Eidt - Ford Motor Company, Dharmveer Podhuturi, Akbar Farahani - Engineering Technology Associates, Inc.

  Material handling of sheet-metal components within the plant or one plant to the other significantly impacts quality and assembly process. Any permanent deformation of sheet metal component contributes to poor quality of an automotive subassembly. One way is to minimize occurrence of unacceptable deformation is to follow trial and error approach. However, such approach is time consuming during launch; in addition cost of stamping and testing prototype panel is high. Therefore a CAE methodology, using dynamic time domain solver ‘LS-DYNA’, was developed to provide design guidance and to examine probability of permanent set in the panel due to manual and robotic handling loads. An outer panel of a liftgate is used as an example to establish this methodology. The CAE results confirmed that proposed design of outer panel is capable to meet handling loads and eliminated need of redesign and saved launch time. This paper discusses a methodology to simulate handling process and evaluate behavior of sheet metal panels subjected to time varying enforced displacements. In this approach FEA techniques and a nonlinear flexible dynamic model are combined. Such approach helped to simulate handling process and to assess relations among material strength, panel topology, and locations of suction cups in end-effectors. Experimental validation of this proposed technique is in progress.

• Assessment of LS-DYNA Scalability Performance on Cray XD1

  Ting-Ting Zhu - Cray Inc.

  Technologists worldwide have now recognized that CAE (Computer Aided Engineering) offers an unprecedented opportunity to revolutionize product development. Today, CAE promises not only increased productivity but also faster time-to-market, lower warranty costs and above all, products that are safer, outperform and work better. With the broad acceptance of the MPI based implementation of LS-DYNA, the manufacturing industry is pushing the limits of scalability as they scramble to meet stringent product design cycle constraints. Microprocessor based cluster systems are increasingly being deployed for production workloads. But, the scalability and system efficiency can be very poor on such systems. The industry goal to reduce time-to-market can be met only if the system has a balanced architecture and the interconnect technology is able to deliver sustained performance for actual applications. In this study, an in-depth analysis will be performed to assess the performance of LS-DYNA on Cray’s XD1 system. A correlation between the hardware features of Cray XD1 and the attributes of LS-DYNA will be made. Various phases involved in a typical crash simulation, such as - initialization, element processing, contact and rigid bodies calculations will be analyzed. An MPI profiling tool will be used to monitor the MPI performance in the context of computation, communication and synchronization aspects of LS-DYNA. The communication patterns and message sizes will be studied for variety of standard benchmarks ( www.topcrunch.org ). The role of Cray XD1’s balanced architecture and the HHTUTU UUTTHH high speed interconnect technology will be presented in the specific context of LS-DYNA and production workloads. Performance results of LS-DYNA on Cray XD1 will be highlighted that truly demonstrate “Application efficiency at scale”.

• Assessment Of Mach Stem Pressures: Comparison Of Experiments With Engineering And Eulerian Models

  Len Schwer (Schwer Engineering & Consulting Services)

  Laboratory scale tests conducted by Kisters and Kuder (2012) provide reflected pressure histories for a 1kg TNT charge detonated at 0.32m above a rigid surface. The pressure histories are measured 1m from the charge using a vertical array of pressure transducers to infer the height of the Mach Stem at this range. Two such vertical arrays, each with 9 pressure transducers at varying heights above the surface, were used, and the test was repeated three times. Four additional configurations with heights- of-burst (HOB) varying from 0.1 to 0.32m and standoff ranges of 0.9 to 1.2m were conducted, but not reported in the present reference. Examination of the measured wave forms allowed Kisters and Kuder to estimate the height of the Mach Stem, a.k.a. triple point, to within 60mm (vertical gauge spacing). The pressure histories from the vertical array measurements provide an opportunity to assess the accuracy of the LS-DYNA air blast engineering model referred to as LOAD_BLAST_ENHANCED, and results from simulations using the LS-DYNA Eulerian solver usually referred to as Multi-Material Lagrangian Eulerian (MM-ALE). In addition to comparisons of maximum pressure, and time-of-arrival (TOA), the time integrated pressure histories provide maximum impulses for comparison.

• Assessment of Motorcycle Helmet Chin Bar Design Criteria with Respect to Basilar Skull Fracture using FEM

  S. Farajzadeh Khosroshahi, M. Ghajari (Imperial College London), U. Galvanetto (University of Padova)

  Statistical studies showed that the chin bar of full-face helmets is the region with the highest number of impacts. In an Australian research, fifty percent of severe impacts took place to the front of the helmet and forty percent of these resulted in Basilar Skull Fracture (BSF). There are two standards, which include criteria for assessing the performance of the helmet’s chin bar, Snell M2015 and ECE 22.05.

• Assessment of the Capacity of a Reinforced Concrete Structure for Impact with Military Jet Aircraft

  M. Miloshev, M. Kostov (Risk Engineering)

  The current paper presents analysis of a reinforced concrete structure for impact with Phantom F-4 military aircraft. The analysis is performed by the missile-target interaction method. The finite element (FE) model of the aircraft is validated by comparison of the load-time function, obtained by numerical impact simulation into rigid planar target to the one, obtained from full-scale impact test. The latter was performed in 1988 at the SANDIA national laboratory in the US and the results were made public. Two models of the jet fuel are investigated – rigid fuel model and Smooth Particle Hydrodynamics (SPH). The rigid fuel model refers to the case where the mass of the fuel is lumped to the structural elements of the fuel tanks. The load-time curves computed by the numerical simulation into rigid wall are compared to the experimental one in Fig. 1. Very good match between the numerical and experimental results is achieved which implies that the FE model captures well the mass and stiffness distribution of the real aircraft and is suitable for performing missile-target interaction analyses. The target is a reinforced concrete structure with an asphalt layer which is laid on top of it. It is assumed that this asphalt increases the capacity of the structure and acts as an energy disspating layer in case of high velocity impact. A number of analyses is performed assuming asphalt material properties, defined for different temperatures and strain rates. The parameter which is compared as a result from the analyses is the area of perforation of the structure. It is related to the ammount of debris which could penetrate, as well as to the assessment of the consequences of possible fire inside.

• ATV and MATV techniques for BEM acoustics in LS-DYNA

  Yun Huang, Zhe Cui (LSTC)

  This paper presents the new ATV (Acoustic Transfer Vector) and MATV (Modal Acoustic Transfer Vector) techniques for BEM acoustics in LS-DYNA, which were implemented recently. Acoustic Transfer Vector provides the transfer function between the normal nodal velocity on structural surface and the acoustic response at selected field points; Modal Acoustic Transfer Vector provides similar transfer function, but is based on the excitation from modal shape vibrations. ATV and MATV reveal the inherent properties of structures and acoustic volume, and can be used to predict radiated noise from vibrating structures when combined with vibration boundary conditions. Particularly they are useful for the acoustic analysis of structures subjected to multiple load cases. Some examples are given to illustrate the application of the ATV and MATV techniques. For ATV, post-processing of the results in the form of binary plot database is also presented.

• Automated Metamodeling for Efficient Multi-Disciplinary Optimisation of Complex Automotive Structures

  Dr. Florian Jurecka - FE-DESIGN GmbH

  The use of multi-disciplinary optimisation methods (MDO) in the development process of complex automotive structures is often hindered by several problems. The required resources for very expensive simulations such as crash or 3D CFD analyses rapidly exceed the means available – especially whenever many input parameters, disciplines or load cases are involved. Furthermore, we have experienced that it can be difficult to assure stable runs of simulation processes over a longer period of time. As a result, ‚trivial’ problems such as missing licenses, an overload in network or hard disk resources can lead to a termination of the optimisation process. Not to mention that an optimisation run based on different disciplines can only start once all disciplines involved have set up their respective simulation models. Even a simple change in only one affected discipline would necessitate the optimisation run to start from scratch (with simulations for all load cases/disciplines to be redone). Here, metamodeling techniques can lead to a significant increase in efficiency since all information on the system behaviour gained from former analyses can be reused e.g. for optimisation runs or sensitivity analyses. In addition to this data storage functionality, the use of metamodels also decouples the occupation of computing resources from the actual use of the information. That means that idle CPU time can be used to collect more information on the product or system leading to reduced computation times in the actual optimisation method. Problems in particular simulation runs do not automatically result in a termination of the MDO method, but can easily be repeated. Consequently, it is also possible to evaluate the different disciplines independently even when other disciplines cannot provide a final simulation model yet. All these advantages together result in a much more efficient usage of computation resources. However, the complexity and diversity of metamodeling techniques often prevent the potential user from these benefits. Typically, the choice between the different metamodel formulations is not easy to make. In this paper, an approach is presented which allows for an automated model selection and fitting process. This approach enables the user to use metamodels rid of the complicated selection and fitting process. This task is undertaken by an optimisation algorithm which automatically generates a large variety of metamodels and accesses their respective applicability by means of statistics. As a result, the user gets the most suitable metamodel for each load case or discipline individually and in addition important information about the accuracy of the approximation. The approach will be illustrated by a typical example of a multi-disciplinary optimisation of automotive structures.

• Automated Metamodeling for Efficient Multi-Disciplinary Optimisation of Complex Automotive Structures

  Dr. Florian Jurecka - FE-DESIGN GmbH

  The use of multi-disciplinary optimisation methods (MDO) in the development process of complex automotive structures is often hindered by several problems. The required resources for very expensive simulations such as crash or 3D CFD analyses rapidly exceed the means available – especially whenever many input parameters, disciplines or load cases are involved. Furthermore, we have experienced that it can be difficult to assure stable runs of simulation processes over a longer period of time. As a result, ‚trivial’ problems such as missing licenses, an overload in network or hard disk resources can lead to a termination of the optimisation process. Not to mention that an optimisation run based on different disciplines can only start once all disciplines involved have set up their respective simulation models. Even a simple change in only one affected discipline would necessitate the optimisation run to start from scratch (with simulations for all load cases/disciplines to be redone). Here, metamodeling techniques can lead to a significant increase in efficiency since all information on the system behaviour gained from former analyses can be reused e.g. for optimisation runs or sensitivity analyses. In addition to this data storage functionality, the use of metamodels also decouples the occupation of computing resources from the actual use of the information. That means that idle CPU time can be used to collect more information on the product or system leading to reduced computation times in the actual optimisation method. Problems in particular simulation runs do not automatically result in a termination of the MDO method, but can easily be repeated. Consequently, it is also possible to evaluate the different disciplines independently even when other disciplines cannot provide a final simulation model yet. All these advantages together result in a much more efficient usage of computation resources. However, the complexity and diversity of metamodeling techniques often prevent the potential user from these benefits. Typically, the choice between the different metamodel formulations is not easy to make. In this paper, an approach is presented which allows for an automated model selection and fitting process. This approach enables the user to use metamodels rid of the complicated selection and fitting process. This task is undertaken by an optimisation algorithm which automatically generates a large variety of metamodels and accesses their respective applicability by means of statistics. As a result, the user gets the most suitable metamodel for each load case or discipline individually and in addition important information about the accuracy of the approximation. The approach will be illustrated by a typical example of a multi-disciplinary optimisation of automotive structures.

• Automated Post Simulation Analysis, Mining, Reporting and Collaboration with d3VIEW

  A. Nair, S. Bala (LSTC)

  Data management, mining, comparison and presentation play vital roles in utilization of Finite Element Analysis for product design and decision making. Post simulation interpretation of results is largely a manual process and interpretation of data points is limited to only a handful of data points. The capability to perform such tasks seamlessly will reduce workload for an engineer and help focus his attention more on engineering rather than spend time generating reports. d3VIEW is a simulation data management and collaboration software that is tightly integrated with LS-DYNA to automate post-simulation analysis. This paper will discuss the evaluation of d3VIEW. Publicly available LS-DYNA finite element models are used to showcase d3VIEW’s capability. d3VIEW’s ability to extract LS-Dyna results, store and compare data, generate reports using templates, visualization and collaboration are highlighted. Collaboration of reports generated automatically with peers and management would give instant access to qualitative and quantitative post processing of simulation results.

• Automated Post-Processing & Report-Generation for Standard Crash & Safety Tests Simulation

  T. Nikolaos (BETA CAE Systems S.A.)

  There are an increasing number of standardized tests, for which a vehicle should comply with. All these tests, usually, require the generation of a standardized report. For the generation of reports for simulated tests, after each solver run, the followed post-processing actions are always the same. Most of the tasks in the post-processing of simulation of road vehicles crash tests, involve repeated actions while, in certain cases, these actions may represent up to 90% of the total. This repetition is proven cumbersome, time-consuming and prone to errors. Therefore, the automation of the execution of those actions and the subsequent report generation is required. This paper presents software tools that automatically process and create reports, for Pedestrian Safety analysis, Occupant Protection in Interior Impact (FMVSS 201U), IIHS structural ratings and Bus Rollover (ECE R66), based ®on LS-DYNA results. These tools streamline the extraction of the results for the respective tests. They lead directly to reports and create overview models for supervisory evaluation in cases of a large number of simulation runs. The automation of complicated post-processing procedures in μETA (mETA), the Post-Processor of BETA CAE Systems S.A., not only saves time and eliminates user’s frustration but it also assures an error-free outcome. Keywords: Post-processing, process automation, reporting, Pedestrian Safety, FMVSS 201U, IIHS, Bus Rollover ECE R66.

• Automatic Analysis of Crash Simulations with Dimensionality Reduction Algorithms such as PCA and t-SNE

  David Kracker (Dr. Ing. h.c. F. Porsche AG), Jochen Garcke (Fraunhofer SCAI), Axel Schumacher University of Wuppertal, Pit Schwanitz (University of Wuppertal)

  The increasing number of crash simulations and the growing complexity of the models require an efficiently designed evaluation of the simulation results. Nowadays a full vehicle model consists of approximately 10 million shell elements. Each of them contains various evaluation variables that describe the physical behavior of the element. Therefore, the simulation models are very high dimensional. During vehicle development, a large number of models is created that differ in geometry, wall thicknesses and other properties. These model changes lead to different physical behavior during a vehicle crash. This behavior is to be analyzed and evaluated automatically. In this article, potentials of several algorithms for dimensionality reduction are investigated. The linear Principal Component Analysis (PCA) is compared to the non-linear t-distributed stochastic neighbor embedding (t-SNE) algorithm. For those algorithms, it is necessary that the input data always has an identical feature space. Geometrical modifications of the model lead to changes of finite element meshes and therefore to different data representations. Therefore, several 2D and 3D discretization approaches are considered and evaluated (sphere, voxel). In order to assess the quality of the results, a scale-independent quality criterion is used for the discretization and the subsequent dimensionality reduction. The simulations used in this paper are carried out with LS-DYNA®. The aim of the presented study is to develop an efficient process for the investigation of different data transformation approaches, dimensionality reduction algorithms, and physical evaluation quantities. The resulting evaluation method should represent physically relevant effects in the existing simulations in a low-dimensional space without human interaction and thus support the engineer in the evaluation of the results.

• Automatic Evaluation of LS-DYNA® Simulation Results Using Statistical Database and Python

  Daxin Wu, Olaf Hartmann (ARRK Engineering)

  Thanks to the significant increase of computational power, full-vehicle crash simulation has become a standard procedure in vehicle crashworthiness design. It has enabled engineers to accommodate constantly shortened development period in automotive industry. On the other hand, with eased access to simulation tools, simulation results flood during the project development. Most of the time, only a small specific portion of the results is analyzed by engineers. Based on internal statistics gathered from various projects, the number of curves in history outputs from a full-vehicle crash simulation varies from 14,000 to 500,000, depending on the model complexity and conventions of the project. Nevertheless, only 0.1 to 1 percent of the entire outputs are used. The rest of the curves are not analyzed mainly due to two reasons, namely little relevance to the focus of the analysis and absence of post-processing method for systematic analysis of a large amount of outputs. However, considering the size of a full vehicle crash model and the complexity of the crash event, a lot of information can be overlooked. Using data mining, history outputs from past simulations can be systematically gathered, processed in a statistical manner and then stored in a database to serve as a reference for future simulations and even as the basis for more advanced evaluations methods. In the scope of this work, we developed a method for automatic evaluation of history outputs of LS-DYNA simulations by comparing them with a reference database created from previous simulation results, which are predecessors or comparable with the new simulation. The comparison identifies the history outputs with the most significant deviations and records the time points, when such discrepancies occur. Furthermore, the spatial information of these history outputs are extracted, namely the positions on the vehicle. The comparison result therefore shows both the time when deviations occur and the structural regions which are most likely responsible for the deviations. This helps determine the sequence of different structural behaviors and their interdependencies. Significant deviations can come from initial differences in the model, which may indicate modelling errors, or arise over time. This tool was adopted in the crash development of a sports car in order to ensure model quality and identify the sequence of different structural behaviors and their causes. In this paper, we present the possibility of automatic evaluation of all LS-DYNA history outputs using python. This serves as a foundation for further evaluation techniques based on big data analysis.

• Automatic Generation of Accurate Material Models for Long Fiber Reinforced Plastics in Crash Simulations

  Timo Schweiger, Jörg Lienhard, Hannes Grimm-Strele, Matthias Kabe

  Long fiber reinforced plastics (LFRPs) offer excellent mechanical properties and are widely used in automotive and aerospace industries. Accurately modeling the behavior of LFRPs under crash conditions is crucial for designing lightweight and safe structures. However, creating reliable material models for LFRPs is challenging due to their complex microstructure and anisotropic nature. This study presents an automatic method to generate highly accurate material models for LFRPs, specifically tailored for crash simulations.

• Automatic Processes for Multiple Analyses

  Miles Thornton, Christopher Bell, David Burton, Paul Davidson, Ben Dennis, Roger Hollamby, Richard Sturt - Arup

• Automating LS-DYNA Simulation Processes using SOFY’s Rapid Application Development Environment RADE.

  Dirk Ulrich - SOFY GmbH, Germany

  Since the first applications of Finite Element Analysis (FEA) in automotive design this technology has gone a long way to become a standard tool fully integrated in the design process of automotive industry. Strongly promoted by progress in mathematics, information and computer technology simulation results have today reached a level of accuracy comparable to physical testing. In parallel developments in software technology – ranging from CAD to graphical interactive pre- and postprocessing - have helped FEA to develop from a work performed by specialists into an industrial tool used by design engineers. Within a product design engineers often have to judge the performance of dozens of design variants by doing very similar Finite Element Analysises. This leads to the requirement to automate the preand postprozessing of FEA to reduce errors and turnaround times and to improve quality and productivity. This paper demonstrates how RADE – the Rapid Application Development Environment – of the commercial pre- and postprocessing package SOFY is used in industry to automate analysis processes from input creation to report generation.

• Automating Oasys PRIMER and Oasys D3PLOT using JavaScript

  Miles Thornton - Arup

  Oasys PRIMER and Oasys D3PLOT now contain JavaScript interpreters. Adding a scripting engine allows the user to automate both pre and post processing tasks. Extensions to the core JavaScript language allow the user to interact with the programs, create and/or manipulate data, create user interfaces, read and write files and extend the functionality of PRIMER and D3PLOT. The syntax is quick and easy to learn. There are several advantages in using scripts: • Quick turnaround – you do not have to wait for new version of PRIMER or D3PLOT • You can keep your application confidential • The script is under your control – you can do it yourself if you wish. This paper describes the scripting technology, outlines possible applications and gives demonstrations in Oasys PRIMER and Oasys D3PLOT.

• Automation of LS-DYNA’s Material Model Driver for Generation of Training Data for Machine Learning based Material Models

  D. Sommer, K. Mitruka, Prof. P. Middendorf (University of Stuttgart)

  The substitution of classical constitutive material models with data-driven models supported by machine learning techniques could provide a leap in the modelling of materials. The most notable benefits are a faster description of new materials without a tedious manual parameter identification procedure, lower computational time for simulations due to efficient computation within the material model and a more efficient selection of the correct material model for the use-case. The base for any data-driven model is adequate amount and quality of training data. Based on this, machine learning techniques can be used to train neural networks such that they learn the relationship between given input and output. The mapping in the machine learning based material model will be the strain measures to the stresses, similar to classical models.

• Automatized Kinetic and Strainfield Based Calibration for a Thermoplastic Material Model using High Speed Tensile Tests

  S. Schilling, P. Suppinger, P. Blome (Autoliv)

  Current and future automotive development cycles are driven by the needs for lightweight designs, cost reductions, comfort- and safety improvements and the reduction of time-to-market. One way to cope with the listed challenges is the usage of thermoplastic materials for integrative designs of components. Among the challenges for passive safety supplier Autoliv to design thermoplastic components, which are placed in the load path of seatbelt components, is the strong dependency on loading velocity of the components. As crash situations are the most dominant load cases for design and functionality, a strong demand for predictive strain rate dependent material models is given. Strain rate effects are next to temperature- and humidity effects the major challenge concerning thermoplastics. As an industrial demand for a comprehensive material database, it needs to be fast, efficient, economical and accurate. Also, the need for a fully automatized material model calibration process is expressed. To fulfill these demands a two-stage reverse engineering process fits test results to analytical approaches for a quasi-static and a strain rate dependent stress-strain response along with an analytic approach for modelling of visco-elasticity and strain rate dependent damage. The needed test results, to which the analytical parameters are fitted, consist of force-displacement as well as strainfield characteristics and were measured using a newly developed high-speed tensile testing device. This device is designed to get close to constant loading velocity of specimen resulting in strain rates up to 𝜀𝜀̇ = 320 𝑠𝑠−1. The accuracy of the test results is ensured by a wedge-to-wedge, self-locking coupling mechanism, a start-up length for acceleration travel of the tensile testing machine as well as a local force gauge. Especially by the local force gauge, consisting of strain gauges arranged as Wheatstone bridge, it is realized that oscillations in force signals of dynamic testing are minimized. The automatized material model calibration routine fed with accurate test results from the high-speed tensile testing device shows promising results to further enhance simulation quality and predictability for the design of thermoplastic components in crash load cases.

• AutoMesher for LS-DYNA Vehicle Modeling

  Ryan Alberson, David Stevens (Protection Engineering Consultants), James D. Walker, Tom Moore (Southwest Research Institute)

  Software has been developed to automatically mesh CAD files in support of expedient modeling of armored vehicles and similar structures. The AutoMesher software is written in Python as well as LSTC’s Script Command Language (SCL). The SCL syntax is similar to C programming, but runs as a script within LSTC’s LS-PrePost® (LSPP) software application. A Python module is used as the interface and a wrapper for LSPP. By leveraging the functions in LSPP through the SCL, nine different algorithms were written to mesh I beams, T beams, angles, rods, plates, tubes, and surface-meshed formed shapes. Logic is used in these algorithms to identify the shape characteristics needed to define an equivalent FEA mesh of the CAD geometry, such as geometric planes that represent flanges or web components of an I-beam. These algorithms are the heart of the AutoMesher and can be used to generate more intelligent meshing solutions. The algorithms and software are described in this presentation. The AutoMesher software was developed by Protection Engineering Consultants (PEC) in support of the Defense Advanced Research Projects Agency (DARPA) Adaptive Vehicle Make (AVM) program, under subcontract to Southwest Research Institute (SwRI). AVM is an ambitious program to reduce the time required for the design, development, and production of complex defense cyber-mechanical systems, such as military ground vehicles, by a factor of five.

• Automotive Door Sealing System Analysis

  Rosa Zhao, Frank Lee, Thomas Oetjens - General Motors Corp.

  Door sealing system is one of the most important automotive quality issues. Problems with door seal system could cause water leakage, wind noise and hard to open or close, which impair customer’s satisfaction of the vehicle. That is why the door seal problem is always among the Hardy Perennial Top 10 list in JD Power Tracking Study. The design rationality and manufacturing process are important aspects for the functionality and performance of a sealing system. However, the door sealing system involves many design variables and manufacturing variables. It is almost impossible to precisely confirm individual quantitative effects on functionalities of these variables. Therefore, computer based simulation of door sealing system is more practical since it can isolate the critical factors and it is cost effective and time efficient. LS-DYNA was used to simulate door seal system. The key structural component, the rubber seal, was modeled and simulated. Different types of elements, material models and contact algorithms from LS-DYNA element, material and contact libraries were tried and compared. Consequently, the best modeling and simulation technology was developed for the door sealing system analysis. The newly developed method showed the great potential of comprehensive studies of door sealing system. The analysis results provided some major parameters, such as seal deformation, contact pressure and energy transformation, which would influence the functionality and performance of the door sealing system. The analysis results have been compared with some available test data, and very good correlations were obtained. The analysis also evaluated the influence of manufacturing deviations. With the results obtained from this analysis, the relationship between the major parameters could be established and used as a tool to derive a better sealing system design at early stage. This analysis method could also be used to evaluate the influence of certain type of process error. Eventually, this analysis method will be developed into a tool that is capable of predicting water leakage, wind noise and hard to open/close problems caused by either product design or manufacturing process.

• Axial Crushing of an Aluminum-CFRP Hybrid Component: FE-Modeling, Simulation and Experimental Validation

  S. Hoque (AIT), A. Rauscher (University of Applied Sciences Upper Austria)

  The crushing performance of aluminum-CFRP (Carbon Fiber-Reinforced Plastics) hybrid generic crash components under axial compression load is experimentally investigated. Aluminum crash components, having similar geometry, are also crushed and compared with the hybrid components. The performance of the hybrid components is found to be twice as much as that of the aluminum components in terms of peak force and specific energy absorption (SEA). Finite element simulations of the crush tests are carried out in LS-DYNA®. The extended 3-parameter Barlat model (MAT36E) is used to characterize the anisotropic elasto-plastic behavior of aluminum sheet. The CFRP laminate is characterized by an orthotropic linear elastic material model (MAT54) with a progressive failure criterion (Chang and Chang). The aluminum-CFRP interface is modeled using tied contact with cohesive mixed mode failure criterion to capture the delamination behavior. Good agreement is found between experiment and simulation in terms of Specific Energy Absorption (SEA) as well as deformation pattern.

• Bake-Hardening Effect in Dual-Phase Steels: Experimental and Numerical Investigation

  David Koch, Filipe Andrade, André Haufe, DYNAmore GmbH, Stuttgart, Germany;, Markus Feucht, Daimler AG, Sindelfingen, Germany

  Typically, the material characterization for the simulation is performed based on the virgin material which is used for the preparation of the corresponding component. However, due to the processing of the material, its mechanical properties may vary greatly. A typical example are materials subjected to forming operations. The work hardening during the forming process changes the local material properties such that the stress necessary for further plastic straining increases. Such effect can actually be captured in numerical simulations by transferring the plastic strain from the forming process into the subsequent step (e.g., a crash simulation). However, several components undergo not only a forming but also a heat process. Experimental evidence shows that the combination of plastic straining and heat treatment can further affect the behavior of a material. Therefore, a closer look at the influence of the pretreatment as well as the development of methods to take this influence into consideration is of great interest.

• Bake-Hardening Effects, Arbitrary Image Data and Finite Point-Set Analysis Results made Accessible with envyo

  C. Liebold (DYNAmore), J. Zerbst (Daimler), S. Hagmann (Porsche), M. Hedwig (Porsche)

  In the recent past, a lot of effort has been made towards the closing of the simulation process chain for all different kinds of materials. Besides the regular transfer of resulting stress, strain, and history data, main focus from a material’s perspective has been on the transfer of fiber orientations from process simulations for continuous fiber reinforced composites [1] together with various homogenization approaches for short fiber reinforced plastic materials [2].

• Ballistic Behaviour of UHMWPE Composite Material: Experimental Characterization and Numerical Simulation

  H. Abdulhamid, P. Deconinck, P.-L. Héreil, J. Mespoulet (Thiot-Ingenierie)

  This paper presents a comprehensive mechanical study of UHMWPE (Ultra High Molecular Weight Polyethylene) composite material under dynamic loadings. The aim of the study is to provide reliable experimental data for building and validation of the composite material model under impact. Three types of dynamic characterization tests have been conducted: in-plane tension, out-of-plane compression and out-of-plane shear. Moreover, impacts of spherical projectiles impact have been performed on larger specimen. Regarding the numerical simulation, an intermediate scale multi-layered model (between meso and macro scale levels) is proposed. The material response is modelled with a 3d elasto-orthotropic law coupled with fiber damage model. The modelling choice using *MAT_ORTHOTROPIC_SIMPLIFIED_DAMAGE is governed by a balance between reliability and computational cost. Material dynamic response is unconventional [1, 2]: it shows large deformation before failure and very low shear modulus and peeling strength. Numerical simulation has been used both during the design and the analysis of tests. Mechanical properties related to elastic moduli and failure strength have been measured. The ballistic numerical model is able to reproduce the main behaviors observed in the experiment. The study has highlighted the influence of temperature and fiber slipping in the impact response of the material.

• BALLISTIC IMPACT MODELING OF COMPOSITE MATERIALS

  Chian-Fong Yen - Materials Sciences Corporation

  A computational constitutive model has been developed to characterize the progressive failure be- haviors of composite laminates under high velocity ballistic impact conditions. The composite failure model has been implemented within LS-DYNA as a regular material subroutine. The inte- grated code was successfully utilized to predict the damage and ballistic behavior of composite laminates subjected to various ballistic impact conditions. The availability of this design tool will greatly facilitate the development of composite structures with enhanced ballistic survivability.

• Ballistic Impact Simulations of an Aluminum 2024 Panel Using *MAT_224 in LS-DYNA® Considering Oblique Incidence and Attitude Angles of a Rectangular Projectile

  C. K. Park, K. Carney, P. Du Bois, C. D. Kan (George Mason University), G. Queitzsch (retired, Federal Aviation Administration), D. Cordasco, W. Emmerling (Federal Aviation Administration)

  The objective of this study is (1) to validate the *MAT_224 model for Aluminum 2024 with complex impact conditions, (2) to evaluate its predictability of ballistic limit and residual velocities of a projectile under various impact conditions, and (3) to investigate the effects of oblique and attitude angle variations of a projectile on penetration to a target plate. The newly developed *MAT_224 model (version 2.0) for Aluminum 2024 was utilized to simulate a series of ballistic impact tests conducted by NASA using a rectangular block projectile of Inconel 718 with sharp edges and corners, impacting Aluminum 2024 flat panels at oblique angles of incidence. A full ballistic impact simulation model was created with over twenty million solid elements and used to conduct approximately one hundred ballistic impact simulations. Overall, the ballistic impact simulations showed highly comparable results with the NASA tests in terms of projectile residual velocities, failure shapes of the target plates, and projectile penetration behavior. Based on a series of ballistic impact simulations, the ballistic limit velocities of the projectile were predicted.

• BatMac: A Battery Macro Model to Simulate a Full Battery in an Electric or Hybrid Car Crash

  P. L‘Eplattenier, I. Caldichoury (LSTC)

  Safety is an important functional requirement in the development of large-format, energy-dense, lithium-ion (Li-ion) batteries used in electrified vehicles. Computer aided engineering (CAE) tools that predict the response of a Li-ion battery pack to various abusive conditions can support analysis during the design phase and reduce the need for physical testing. In particular, simulations of the multiphysics response of external or internal short circuits can lead to optimized system designs for automotive crash scenarios.

• Batted-Ball Performance of a Composite Softball Bat as a Function of Ball Type

  Jennifer Yee (Combat, University of Massachusetts), James A. Sherwood (University of Massachusetts), Stephen Fitzgerald (Combat)

  The ideal models of softball bats and balls should have the flexibility to allow for the ability to capture how BBS varies as a result of changes in bat and ball constructions. If such models were available, then the design engineer could customize the bat design with the goal to maximize the BBS for a given ball construction. A credible finite element model of the ball-bat collision for softball is challenging. Achieving such a model is difficult primarily because of variations in the processing of the polyurethane cores of softballs which can yield different properties of the overall ball, e.g. hardness and liveliness, and the response of the softball during a bat-ball collision is rate dependent. The mechanical behavior of the composite bat is slightly less challenging to model because the bat material can be assumed to be essentially linear elastic unless significant material damage is induced during the collision. Experimental and finite element methods were used to model the collision between a composite softball bat and softballs of different COR (Coefficient of Restitution) and compression specifications. An example model is shown in Figure 1. Experimental bat characterization methods included barrel compression and modal analysis. Experimental softball characterization methods included COR, CCOR (Cylindrical Coefficient of Restitution), compression and dynamic stiffness. Finite element models were built in HyperMesh and analyzed in LS-DYNA®. Softballs were modeled using LS-DYNA material models #6, #57 and #83, and the composite softball bat was constructed according to the manufacturer’s specifications using *PART_COMPOSITE. Three methods to calibrate the finite element softball models were investigated and included “flat-surface” and “cylindrical-surface” coefficients of restitution and DMA (dynamic mechanical analysis). The “cylindrical-surface” test was found to be the most effective method of calibration to predict the batted-ball speed (BBS) as measured in bat/ball impact testing. This paper presents a summary of the complimentary experimental and finite element studies that were completed to develop a bat-ball collision model for the research of composite softball bats. Softballs were characterized using simple tests, and finite element models of the softballs were calibrated to yield good correlation to the experimental characterization tests. The calibrated softball models were then used to explore their ability to correlate with bat-ball collisions using a composite softball bat.

• Battery Abuse Case Study Analysis Using LS-DYNA ®

  James Marcicki, Alexander Bartlett, Xiao Guang Yang, Valentina Mejia, Min Zhu, Yijung Chen (Ford Research and Innovation Center), Pierre L’Eplattenier, Iñaki Çaldichoury (LSTC)

  Battery abuse research and modeling, Spatially-resolved battery modeling, Electro-thermal battery modeling. As Lithium-ion batteries see increasing use in a variety of applications, anticipation of the response to abuse conditions becomes an important factor in designing optimized systems. Abuse scenarios with potential relevance to the automotive industry include crash-induced crush leading to an internal short circuit, external short circuit, or thermal ramp, and overcharge conditions. Simulating each of these abuse scenarios requires sophisticated modeling tools that span multiple physical and electrochemical phenomena, as well as handle complex geometries that accurately represent battery cells, modules, and packs. The three-dimensional, transient analysis capabilities of LS-DYNA can be leveraged to simulate the battery response with a high degree of spatial resolution, which is widely considered a prerequisite for predicting the highly localized phenomena involved in the onset of thermal runaway. The electrical, electrochemical and thermal response of the new LS-DYNA battery model can be coupled to the mechanical solver using a variety of approaches, ranging from one-way coupling based on a time-scale analysis to tight two-way coupling. Several battery abuse case studies will be examined to verify the capability of the modeling tools. The impact of hardware size will be investigated, as the thermal behavior and corresponding severity of the abuse response changes depending on the number of cells and their configuration within a module. Experimental data will be used to estimate parameters, confirm the model capability, and identify areas of future work to improve the fidelity and ease of implementation of the simulation tool. Multiple hardware types will be compared to demonstrate the relationship between cell performance and module abuse response.

• Battery Abuse Simulations Using LS-DYNA

  P. L'Eplattenier (LSTC)

  Safety is an important functional requirement in the development of large-format, energy-dense, lithium-ion (Li-ion) batteries used in electrified vehicles. Computer aided engineering (CAE) tools that predict the response of a Li-ion battery pack to various abusive conditions can support analysis during the design phase and reduce the need for physical testing. In particular, simulations of the multiphysics response of external or internal short circuits can lead to optimized system designs for automotive crash scenarios. Recently, a so called “distributed randles circuit” model was introduced in LS-DYNA in order to mimic the complex electrochemistry happening in the electrodes and separator of lithium ion batteries. This model is based on electrical circuits linking the positive and negative current collectors reproducing the voltage jump, internal resistance and dumping effects occurring in the active materials. These circuits are coupled with the Electromagnetics (EM) resistive solver to solve for the potentials and current flow in the current collectors and the rest of the conductors (connectors, busses, and so forth). The EM is coupled with the thermal solver to which the joule heating is sent as an extra heating source, and from which the EM gets back the temperature to adapt the electrical conductivity of the conductors as well as the parameters of the Randles circuits. One of the advantages of the Randles circuit model is the relative easiness to introduce internal short circuits by just replacing the Randles circuits in the affected area by a short resistance. The Randles circuit model also is coupled with the mechanical solver of LS-DYNA where the deformations due to a battery crush allow the definition of criteria to initiate internal shorts. Up to now, the Randles circuit model was only available on solid elements. So the user had to create a mesh with all the layers of a cell (positive current collector, positive electrode, separator, negative electrode, negative current collector, negative electrode, separator, and so forth), and define segment sets of each of the current collectors to connect them by Randle circuits in a distributive way. The construction of the case was cumbersome and the mechanical solver often presented limitations on solid elements with one very small dimension compared to the other ones due to the extreme thinness of the different layers. The mechanical deformation of a succession of stiff layers (current collectors) and very soft ones (electrodes and separators) also was a challenge. Recently, the Randles circuit model has been extended to composite Tshells. These new elements promise a better and faster mechanical resolution, and make the setting of the simulations much easier for the user. Finally, a new battery packaging environment is being developed in LS-PREPOST helping with the setup of cell or multi-cell cases. In section 2, we will present the new battery cell model on composite Tshell and give some first example of internal short simulations, and in section 3, we will present the new battery packaging environment in LS-PREPOST

• Battery Cooling Simulation using STAR-CCM+

  D. Grimmeisen, M. S. Schneider (Cascate)

  A generic Li-ion battery pack as typically used in an electric vehicle is simulated in STAR-CCM+, using an analytical model for the electrochemical battery behavior and a thermal/flow simulation with conjugate heat transfer to determine the cooling efficiency. A single Li-ion battery cell is modeled in Battery Design Studio. This model is then used in the Battery Simulation Module of STAR-CCM+, which allows to embed the cell within an electric circuit and to put it under a prescribed load. The battery model then calculates the heat development in the cell based on the load and the electrochemical model. This heat is applied as a distributed heat source in the fluid simulation, which can then be used to investigate and optimize the cooling efficiency.

• Battery simulation in the crash load case

  Slides of the presentation from S. Rybak (EDAG)

• Behaviour and Modelling of Dual-Phase Steels

  Venkatapathi Tarigopula, Odd Sture Hopperstad, Magnus Langseth, Arild Holm Clausen - Norwegian University of Science and Technology (NTNU)

  Dual-phase steels are being increasingly considered for application in vehicle structural crash components because of their combined attributes of high-strength and good formability characteristics. Accurate prediction of such components, which are often made of formed components, is necessary to reduce the cost of physical tests. The non-linear finite element method is an efficient and reliable tool for the design of new components. The reliability of the finite element analyses depends on the accuracy of the constitutive and fracture models. To support the engineering applications of dual- phase steels for crash and forming events, both strain hardening and strain rate hardening must be thoroughly modelled for general loading paths. In this paper, an elasto-viscoplastic phenomenological model is adopted to represent the material behaviour of dual-phase steels. The constitutive model is formulated in the framework of phenomenological continuum mechanics. The main ingredients of the model include a non-quadratic yield criterion, the associated flow rule and non-linear isotropic and kinematic hardening. The model is within the class of plasticity models proposed by Chaboche [1] and Lemaitre and Chaboche [2] for application to monotonic, non-proportional and cyclic loading conditions. The constitutive model is also able to depict viscous characteristics of the material. The material was experimentally characterized under different loading conditions suited for crash and forming events. Figure 1 depicts the approach embraced in this research for identification of material parameters for the utilized model from material tests. The conventional material tests are providing data for the calibration of the model. Simple tension tests were used to characterize the elastic parameters, the yield surface and the isotropic hardening parameters. Non-proportional tension tests were used to identify the kinematic hardening parameters. Additionally, viscous parameters were identified from the corresponding tension tests over a wide range of strain-rates. The predictive capability of the adopted numerical model is assessed against the material behaviour at elevated rates of strain and the material behaviour under strain-path changes. Particularly, phenomena like dynamic localisation, large plastic deformations have given due importance for validity of the numerical model. Moreover, the same model is validated for crashworthiness performance of dual-phase steel generic components. The model provides results which are in good agreement with the experimental observations. In this work, the non-linear explicit FE code LS-DYNA was used for numerical computations.

• Behaviour and Modelling of Dual-Phase Steels

  Venkatapathi Tarigopula, Odd Sture Hopperstad, Magnus Langseth, Arild Holm Clausen - Norwegian University of Science and Technology (NTNU)

  Dual-phase steels are being increasingly considered for application in vehicle structural crash components because of their combined attributes of high-strength and good formability characteristics. Accurate prediction of such components, which are often made of formed components, is necessary to reduce the cost of physical tests. The non-linear finite element method is an efficient and reliable tool for the design of new components. The reliability of the finite element analyses depends on the accuracy of the constitutive and fracture models. To support the engineering applications of dual- phase steels for crash and forming events, both strain hardening and strain rate hardening must be thoroughly modelled for general loading paths. In this paper, an elasto-viscoplastic phenomenological model is adopted to represent the material behaviour of dual-phase steels. The constitutive model is formulated in the framework of phenomenological continuum mechanics. The main ingredients of the model include a non-quadratic yield criterion, the associated flow rule and non-linear isotropic and kinematic hardening. The model is within the class of plasticity models proposed by Chaboche [1] and Lemaitre and Chaboche [2] for application to monotonic, non-proportional and cyclic loading conditions. The constitutive model is also able to depict viscous characteristics of the material. The material was experimentally characterized under different loading conditions suited for crash and forming events. Figure 1 depicts the approach embraced in this research for identification of material parameters for the utilized model from material tests. The conventional material tests are providing data for the calibration of the model. Simple tension tests were used to characterize the elastic parameters, the yield surface and the isotropic hardening parameters. Non-proportional tension tests were used to identify the kinematic hardening parameters. Additionally, viscous parameters were identified from the corresponding tension tests over a wide range of strain-rates. The predictive capability of the adopted numerical model is assessed against the material behaviour at elevated rates of strain and the material behaviour under strain-path changes. Particularly, phenomena like dynamic localisation, large plastic deformations have given due importance for validity of the numerical model. Moreover, the same model is validated for crashworthiness performance of dual-phase steel generic components. The model provides results which are in good agreement with the experimental observations. In this work, the non-linear explicit FE code LS-DYNA was used for numerical computations.

• Behaviour model for semi-crystalline polymer, application to crashworthiness simulations

  R.Balieu, F.Lauro, B.Bennani, B.Bourel - Univ Lille Nord de France, K.Nakaya, E.Haran - TOYOTA MOTOR EUROPE

  Today polymer materials are frequently used in the transport domain with more severe specification requirements. The behaviour modeling and failure prediction have consequently become a priority. In this paper, an elasto- viscoplastic behaviour model is presented, with non associated plasticity, damage and strain rate effect, which represents the observed behaviours of a semi-crystalline polymer under dynamic loading.

• Belt Modelling in LS-DYNA®

  Mikael Dahlgren, Abhiroop Vishwanatha, Anurag Soni (Autoliv Sweden, India, North Germany), Klas Engstrand, Jimmy Forsberg (DYNAmore Nordic AB), Isheng Yeh (LST LCC)

  Belt modelling in LS-DYNA has gone from 1D-belt elements, through hybrid belt modelling into 2D seatbelt elements. The current paper investigates recently developed features in LS-DYNA such as bending, strain-rate and orthotropic material behavior. A short description of the evolution of belt modelling is also given. Belt modelling in LS-DYNA has in the past and in the closest future included modelling of sliprings which are points in space where the belt elements pass through. Typical, these are located at sharp directional changes in the belt routing, e.g. B-pillar, D-ring and buckle tongue. Currently, it is the slipring functionality that inhibits users from using an ordinary element and material, of their own selection, to model the belt. Both 1D and 2D belt elements are assigned with *MAT_SEATBELT as it is the only material compatible with sliprings. 2D belt elements in LS-DYNA is a combination of 1D-belt elements along the length direction of the belt and 2D membrane elements made of a MAT_FABRIC material created internal in LS-DYNA. The MAT_FABRIC is created based on *MAT_SEATBELT values. This means current *MAT_SEATBELT in LS-DYNA do not carry any bending loads. The new feature development makes the coating functionality found for MAT_FABRIC available in *MAT_SEATBELT_2D. This enables the bending load carrying possibilities for the 2D belt elements in LS-DYNA. Apart from this feature strain-rate dependency and orthotropic material behavior have been added to the 2D belt elements. It will be shown that the interaction between occupant and belt is improved. It will also be shown that the behavior of an unloaded belt is improved. Finally, there is a short outline of foreseen future needs regarding belt modelling features.

• BEM Methods For acoustic and vibroacoustic problems in LSDYNA

  Souli Mhamed, Yuang Yun, Zhe Cui, Zeguar Tayeb (LSTC)

  The present work concerns the new capability of LS-DYNA in solving acoustic and vibroacoustic problems in time domain and frequency domain, using the following LSDYNA Cards: *MAT_ACOUSTIC *FREQUENCY_DOMAIN_ACOUSTIC_BEM *FREQUENCY_DOMAIN_ACOUSTIC_FEM *FREQUENCY_DOMAIN_SSD In vibroacoustic problems, which are assumed to be weak acoustic-structure interactions, the transient structural response is computed first. By applying the FFT, it is transformed into a frequency response. The obtained result is taken as boundary condition for the acoustic part of the vibro acoustic problem. Consequently, the radiated noise at any point into space can be calculated. The new developed LS-DYNA keyword is based on boundary element method (BEM) in which only the surface of the acoustic domain needs to be discretized. Besides BEM that solves the Helmholtz equation as a linear system, the new card allows, also, to use two other approximate Rayleigh and Kirchhoff methods. Both methods do not require a system of equations to be assembled and solved. Consequently, they are faster than BEM. Rayleigh method assumes that the radiating structure is a plane surface clamped into an infinite rigid plane. In Kirchhoff method, BEM is coupled to FEM used for acoustics in LS-DYNA by prescribing non reflecting boundary condition. In this case, at least one fluid layer needs to be merged to the vibrating structure.

• BEM Methods For acoustic and vibroacoustic problems in LS-DYNA

  Yun Huang - Livermore Software Technology Corporation, Mhamed Souli - University of Lille, Rongfeng Liu - JSOL Corporation

  This paper presents the new developments of finite element methods and boundary element methods for solving vibro-acoustic problems in LS-DYNA. The formulation for a frequency domain finite element method based on Helmholtz equation is described and the solution for an example of a simplified compartment model is presented. For boundary element method, the theory basis is reviewed. A benchmark example of a plate is solved by boundary element method, Kirchhoff method and Rayleigh method and the results are compared. A dual boundary element method based on Burton-Miller formulation is developed for solving exterior acoustic problems which were bothered by the irregular frequency difficulty. Application of the boundary element method for performing panel contribution analysis is discussed. These acoustic finite element and boundary element methods have important application in automotive, naval and civil industries, and many other industries where noise control is a concern.

• BEM Methods For Acoustic and Vibroacoustic Problems in LS-DYNA

  M. Souli, Y. Huang, R. Liu (LSTC, University of Lille Laboratoire Mecanque de Lille, JSOL Corp.)

  The present work concerns the new capability of LS-DYNA® in solving acoustic and vibroacoustic problems using a new keyword *FREQUENCY_DOMAIN_ACOUSTIC_BEM In vibroacoustic problems, which are assumed to be weak acoustic-structure interactions, the transient structural response is computed first. By applying the FFT, it is transformed into a frequency response. The obtained result is taken as boundary condition for the acoustic part of the vibro acoustic problem. Consequently, the radiated noise at any point into space can be calculated. The new developed LS-DYNA keyword is based on boundary element method (BEM) in which only the surface of the acoustic domain needs to be discretized. Besides BEM that solves the Helmholtz equation as a linear system, the new card allows, also, to use two other approximate Rayleigh and Kirchhoff methods. Both methods do not require a system of equations to be assembled and solved. Consequently, they are faster than BEM. Rayleigh method assumes that the radiating structure is a plane surface clamped into an infinite rigid plane. In Kirchhoff method, BEM is coupled to FEM used for acoustics in LS-DYNA by prescribing non reflecting boundary condition. In this case, at least one fluid layer needs to be merged to the vibrating structure.

• Benchmark as decision support for cloudification: Moving CAE and HPC to the cloud increases quality and efficiency of simulations

  C. Woll (GNS Systems)

  A decision in favor of the cloud and the associated organizational changes are of central strategic importance for automotive OEMs and their suppliers. In advance, it is important to clarify whether existing organizational structures and processes can actually be optimized with the help of the cloud. To this end, we regularly carry out benchmarks for well-known customers as a decision-making aid. In the presentation, we will present a benchmark with real productive jobs based on existing data in the customer's specific environment. Mapping the workflow with selected CAE applications in the cloud provided a realistic basis for evaluation of their benefits and costs. In addition to comparing runtimes and results of selected benchmark jobs, our experts tested the quality of remote work in a workstation scenario for selected finite element analyses (FEA), Computational Fluid Dynamics analyses (CFD) and iterative analyses.

• Benchmark of Frequency Domain Methods for Composite Materials with Damage using LS-DYNA®

  Myeong-Gyu Bae, Seonwoo Lee (THEME Engineering, Inc.)

  The composite material is widely used in the structures as aircrafts, satellites, ships, automobiles, and so on which demand light weight and high performance. A various type of damage could occur through low-speed impacts and fatigue loads. It is generally known that the assessment of the natural frequency by vibration testing is a very attractive method as a Non-Destructive Test (NDT) and the vibration response of a composite structure can be utilized as an indicator of damage. In this paper, a desirable FE modeling technique regarding composite types (Laminated/Sandwich) and laminate methods of composite material were investigated using LS-DYNA. Firstly, according to the laminated properties of composite material (number of layers, anisotropy, shape, etc.), frequency responses were compared between the latest theories and the latest version of LS-DYNA. Secondly, various types of damage in cantilever beam with composite material were represented and estimated in FE model and those frequency responses were compared among experiments, LS-DYNA, and other FE code. Finally, delamination phenomenon in rectangular plate with composite material was represented and estimated in FE model and those frequency responses were compared between experiment and LS-DYNA. It was evaluated and verified that the prediction for the tendency of natural frequency using the frequency domain method in LS-DYNA could be appropriate for composite materials with or without damage.

• Benchmark of LS-DYNA® for Off-shore Applications according to DNV Recommended Practice C208

  Marcus Lilja (DYNAmore Nordic AB)

  The use of non-linear FEA is growing in the offshore industry. Det Norske Veritas AS (DNV), one of the world’s largest ship and offshore classification societies to the maritime industry, has developed a Recommended Practice (DNV-RP-C208) on the usage of non-linear implicit finite element simulations in offshore applications. DNV-RP-C208 creates a de facto standard for structural load capacity analysis of off-shore structures. The Recommended Practice in combination with handbook formulas and empirical data create a de facto standard that will be used for investigations, studies and dimensioning off-shore structures for years to come. The Recommended Practice contains several benchmark problems with references solutions that can be used to verify a finite element software and the modeling methodology. This paper presents results from LS‑DYNA for a selection of these benchmark problems , ranging from beam bending problems with elasto-plastic behavior to instability and collapse analysis. All benchmark problems are solved using the implicit non-linear solver. Development of new features in LS‑DYNA and LS-PrePost® were necessary in order to complete the task. This paper presents results from the benchmarks, solution techniques, and the newly developed features.

• Benchmark of Topology Optimization Methods for Crashworthiness Design

  C. H. Chuang, R. J. Yang (Ford Motors Company)

  Linear structural topology optimization has been widely studied and implemented into various engineering applications. Few studies are found in the literature which deals with nonlinear structures during vehicle impact events. One of the major challenges for nonlinear structural topology optimization is the unavailability of design sensitivities in impact simulations, due to the highly nonlinear and computationally intensive nature of these problems. In this paper, three commercially available methods are reviewed and discussed: Equivalent Static Loads (ESL), Hybrid Cellular Automata (HCA), and Inertia Relief Method (IRM). A vehicle structure, subjected to a full frontal impact, is used to compare the topology optimization results generated using HCA and IRM.

• Benchmark Study on the AIRBAG_PARTICLE Method for Out-Of-Position Applications

  Wenyu Lian - General Motors, Dilip Bhalsod - Livermore Software Technology Corporation, Lars Olovsson - IMPETUS Afea

  The demands for developing safety restraint systems that perform well under Out-Of-Position (OOP) conditions have increased significantly in recent years. At the same time, the development of simulation capabilities for OOP have made progress in most major crash/safety software, such as the coupled Lagrangian-Eulerian approach (here referred to as AIRBAG_ALE) in LS-DYNA® by LSTC. Similar technologies are applied in MSC-Dytran by MSC and Madymo_CFD (Madymo) by TNO. A somewhat different approach is the FPM method in PAMCRASH by ESI. The AIRBAG_ALE capability in LS-DYNA, MSC-Dytran, and Madymo_CFD use loose-coupling techniques to couple the Lagrangian finite element airbag with a flow domain modeled with an Eulerian or ALE description of motion. PAMCRASH uses a particle based Lagrangian method, referred to as the Finite Point Method (FPM), for the description of the gases inside the airbag. All these methods share the same challenges associated with the coupling of the gas flow to folded bags under high speed deployment. Generally, the computations require considerable CPU power. The improved AIRBAG_ALE algorithm was developed in 2004 by Lian, Olovsson and Bhalsod [1]. In the same year, a set of benchmark problems were proposed by Lian at the SAE Conference [2]. A driver side airbag OOP study using AIRABG_ALE was presented in 2004 at LS-DYNA users’ Conference [3]. During the last few years, some modeling difficulties using AIRBAG_ALE have been reported. To overcome the difficulties, the Corpuscular Method (here referred to as AIRBAG_PARTICLE) was developed by Olovsson [4]. This study is intended as an evaluation of the accuracy, stability and efficiency of AIRBAG_PARTICLE compared to AIRBAG_ALE in OOP applications. More specifically, in this work the benchmark problems in ref. [2] have been studied using AIRBAG_PARTICLE. The results of AIRBAG_PARTICLE and AIRBAG_ALE are discussed.

• Benchmarking Concrete Material Models Using the SPH Formulation in LS-DYNA®

  Brian Terranova, Research Engineer, University at Buffalo;, Andrew Whittaker, Professor and MCEER Director, Department of Civil, Structural, and Environmental Engineering, University at Buffalo;, Len Schwer, Schwer Engineering & Consulting Services, 6122 Aaron Court, Windsor, California, 95492, U.S.

  A model of a cylinder with a diameter and height of 400 mm was constructed in LS-DYNA using SPH particles to investigate the unconfined, quasi-static behavior of three concrete material models (i.e., MAT016, MAT072R3, and MAT159) in axial compression. Models were also prepared using Lagrangian solid elements and analyzed in axial compression to generate benchmark stress-strain data. Mesh refinement studies were conducted for the SPH cylinder to investigate the effects of particle spacing on predictions of elastic modulus and peak average axial stress. Analysis of the Lagrangian model showed post-peak softening for MAT072R3 and MAT159 and non-softening (i.e., perfectly plastic) behavior for MAT016. The SPH cylinder reasonably recovered the elastic modulus and peak average axial stress of the Lagrangian cylinder for all three material models, but the post-peak behavior predicted using the Lagrangian cylinder was not recovered using the SPH cylinder for material models MAT072R3 and MAT016.

• Benefits of coupling FLACS-CFD® and LS-DYNA® for hydrogen safety applications

  L. Paris, M. Duchateau (Gexcon France), P. GLAY (DYNAmore France)

  There is a need for transitioning to an energy system with less greenhouse gas emissions and more sustainable energy production and consumption. A long-term structural change in energy systems is needed. Germany and France, among other countries, have decided to scale up the green hydrogen sector, with fundings of 9 billion and 7 billion euros respectively in the next 10 years.

• Benefits of Scalable Servers with Global Addressable Memory for Crash Simulation

  Christian Tanasescu, Kevin Fox - SGI

• Benefits of Scalable Server with Global Addressable Memory for Crash Simulation

  Christian Tanasescu, Nick Meng - SGI Inc.

  A wide variety of industries rely on mechanical computer-aided engineering (CAE) to improve design quality, reduce design-cycle time, and control costs. In designing automobiles, the manufacturers must meet different government regulations for vehicle safety. The maturity of Explicit Finite Element methods and the increasing computational power of today's computers have allowed the automotive industry to incorporate the Crash simulation technology in the critical path of the design process. As the application of Crash simulation moves from the component level analysis to the system level, the complexity and the size of the models increase continuously. By combining the capabilities of Intel® Itanium® 2 processors, the open-source Linux® operating system, and SGI® NUMAlink(tm) technology, the SGI Altix family of servers and superclusters with Global Addressable Memory (GAM) is uniquely able to meet the needs of advanced CAE simulation for product development. This paper will outline the features and benefits of using SGI Altix systems with Itanium® 2 processors running LS-DYNA. With the dramatic increase of the price performance of modern high performance computers, the model sizes of car crash and metal stamping simulations have been constantly increasing in recent years. Nowadays, a 1 Million element model is a common case. For large models, highly scalable computers and software play crucial roles in reducing turnaround time for simulations. The combination of the domain decomposition based LS-DYNA and the highly scalable SGI cc-NUMA system is an ideal solution for reducing simulation turnaround time. After briefly introducing the SGI cc-NUMA architecture and the benefits for scalable applications like LS-DYNA, based on recent performance data on the SGI Altix family of systems, we will address the simulation grid concept enabled by a large shared-memory architecture like the SGI Altix 3700. This aims at making the workflow more efficient, not only improving the solver performance. Multi-terabyte datasets can be loaded entirely into memory and operated upon without disk-swapping. In addition, expanding the processing paradigm with I/O and graphics pipes connected directly to the large memory, results in dramatically improved performance and foster collaborative engineering.

• Benefits of the AMD Opteron Processor for LS-DYNA

  Dawn Rintala - Advanced Micro Devices, Inc.

• Biomechanical analysis of whiplash injuries; women are not scaled down men

  Mordaka J., Gentle C. R. - Nottingham Trent University

  Whiplash is the most common soft tissue injury sustained in car accidents. The term is commonly associated with hyperextension of the neck as the head rotates backwards in rear end collisions but the exact injury mechanism is not fully understood because the neck is an anatomically and mechanically complex structure. Experimental studies of the mechanism of injury are limited by several ethical and practical factors, so biomechanical computational simulation, based upon experimental research and mathematical modelling, appears to be the most appropriate method of investigation. During the last decade, significant progress has been made in improving car occupant safety through the use of safety devices, such as airbags and advanced seat belts, as well as the construction of the car body itself. Much still needs to be done, especially for female occupants, because statistically they incur twice the risk of whiplash injury as male car occupants. No simple explanation has so far been found for this difference. It is thought that the anatomic dissimilarity of the sexes is the principal reason, but there are undoubtedly a number of secondary, sociological reasons: women tend to drive smaller cars than men and are more likely to be passengers. The lack of a full explanation arises from the fact that, although there have been several FE-models of the male cervical spine reported, female models are rarely documented. This paper addresses the problem by developing a biomechanical FEM model of the 50th and the 5th percentile female cervical spines, based on the earlier published male model created at the Nottingham Trent University, which relies on grafting a detailed biomechanical model of the neck and head onto a standard HYBRID III dummy model. All numerical analyses have been undertaken using LS-DYNA. Special attention was paid to the behaviour of the scaled down male model in comparison with the model, which included female characteristic features. FEM models of males and females in a representative seat were therefore subjected to 9.5 km/h rear-end simulated collisions and were compared against reported experimental tests. The detailed behaviour varied significantly with gender. The female models revealed greater and earlier peak horizontal acceleration of the head and smaller peak relative extension than the male models. It was concluded that the presented FE models were reasonably in accordance with available crash data on instrumented volunteers in terms of head motion.

• BioRID II Dummy Model Development -- Influence of Parameters in Validation and Consumer Tests

  S. Stahlschmidt, B. Keding, U. Franz - DYNAmore GmbH, Germany, A. Hirth - DaimlerChrysler AG, Germany

  Whiplash injuries frequently occur in low speed rear crashes. Many consumer and insurance organizations use the BioRID II dummy, to assess the risk of whiplash injuries in car accidents. An LS-DYNA model of the BioRID II dummy has been developed by DYNAmore GmbH in cooperation with the German Automotive Industry. In the consortium a huge effort has been made to build a test database for the development of the FE-dummy. This paper describes the effort performed to generate the experimental data for material, component and full dummy validation. The dummy contains a considerable number of pre-stressed parts which can not be neglected since it stiffens the neck significantly. In order to capture the occurring pre-stresses appropriately the modeling techniques require the application of new features in LS-DYNA and specific handling during pre-processing. The paper describes the model and shows its performance in validation tests. Finally, different whiplash simulations are used to emphasize influences of selected parameters on injury criteria of the BioRID II model.

• Biotex BigBag Simulation - LS-DYNA Airbag Tool Unusual Application

  C. Weinberger, B. Hirschmann (4a engineering); Johanna Eichelter (Franz S. Huemer)

• Bird Strike Analysis of Aircraft Engine Fan

  Y.N. Shmotin, P.V. Chupin, D.V. Gabov - NPO SATURN, А.А. Ryabov , V.I. Romanov , S.S. Kukanov - Sarov Engineering Center

  Safety in accidental conditions is one of the important requirements an aviation jet engine must meet. It is known that one of quite possible and very dangerous accident is a bird strike into the engine in the flight. This case is characterized by the high speed impact of the bird onto rotating blades of the fan, causing large dynamic deformations of the blades and other elements which may lead to disintegration of the construction. That’s why numerical investigations of the bird strike are very important and should be implemented during design stage of a development process. The proposed paper presents some results of numerical simulations of dynamic deformations of the fan blades loaded by the bird impact, obtained by LS-DYNA code. There is an analysis of the numerical results and their verification by comparison with experimental data.

• Bird Strike Analysis of Aircraft Engine Fan

  Y.N. Shmotin, P.V. Chupin, D.V. Gabov - NPO SATURN, А.А. Ryabov , V.I. Romanov , S.S. Kukanov - Sarov Engineering Center

  Safety in accidental conditions is one of the important requirements an aviation jet engine must meet. It is known that one of quite possible and very dangerous accident is a bird strike into the engine in the flight. This case is characterized by the high speed impact of the bird onto rotating blades of the fan, causing large dynamic deformations of the blades and other elements which may lead to disintegration of the construction. That’s why numerical investigations of the bird strike are very important and should be implemented during design stage of a development process. The proposed paper presents some results of numerical simulations of dynamic deformations of the fan blades loaded by the bird impact, obtained by LS-DYNA code. There is an analysis of the numerical results and their verification by comparison with experimental data.

• Bird Strike and Fan Blade Out Using LS-DYNA at Snecma
• Bird Strike and Fan Blade Out Using LS-DYNA at Snecma
• Bird Strike Modeling Using a New Woven Glass Failure Model

  Lorenzo Iannucci, Mauricio Donadon - Imperial College London

  The bird strike impact problem is an increasing menace to the composite aerospace designer, especially since more aerospace components are being manufactured from composite materials. The LS-DYNA FE code is often used to model such an event as it can accurately represent the bird material behaviour and the contact between the bird and the structure. However, numerical simulations are usually accompanied by a parallel testing programme to validate the numerical simulations for some of these impact scenarios. The present paper described the implementation of an improved damage mechanics based material model to simulate the progressive failure of woven glass composites. A series of bird strike impacts on flat panels fabricated from low cost woven glass composite materials are used to validate the material model for practical composite component applications. The panels are modelled with shell elements only. The new material model can capture the strain rate enhancement to strength and strain observed for woven glass materials using a damage lag concept. A hydrodynamic model for the bird, based on 90% water and 10% air, is used to represent the behaviour of the bird for all impact scenarios considered. The bird is heterogeneous in nature, however, a uniform material behaviour is assumed with a geometry based on a 2:1 length: diameter ratio with a cylindrical body and spherical end caps using mesh less Smooth Particle Hydrodynamic (SPH) techniques. Appropriate contact definitions are used between the bird and the composite panel. The simulations results are compared to experimental results and conclusions drawn.

• Bird Strike Simulation for BA609 Spinner and Rotor Controls

  Cheng-Ho Tho, Michael R. Smith - Bell Helicopter Textron Inc.

  Bird strike incidents are not uncommon and cost the U.S. civil aviation industry approximately $495 millions and 631,341 hours of downtime annually [1]. The development test to meet the bird strike certification requirements is very costly and time-consuming. This paper presents the bird strike analysis using the Arbitrary Lagrangian- Eulerian (ALE) technique in LS-DYNA for the BA609 spinner and rotor controls assembly shown in Figure 1. The objective is to reduce the development costs and cycle time while achieving weight-efficient resistant design by accurately predicting the composite failures and structural impact performance – with the ultimate goal of certifying by analysis only. The spinner assembly provides the swashplate drive load path and aerodynamic fairing for the rotor hub and controls. The failure of the spinner assembly could result in loss of the aircraft. Therefore the assembly must show compliance with “continued safe flight and landing” requirements following the high-energy bird impact. An idealized cylinder with hemispherical ends surrounded by air, which is modeled as 1-point ALE solid elements, is used to represent the bird model. The bird strike finite element model is validated through correlation with the tests conducted at the Southwest Research Institute of San Antonio in February 2005. This paper analyzes three most load-critical test conditions and evaluates the structural failures of the spinner assembly subjected to the bird strike dynamic loads. Figure 2 shows the correlation of one of the airplane mode shots for a 4.0-lb [1.8-kg] bird fired from a compressed gas gun at 240 kts [127.3 m/s] impact velocity targeting at the upper spoke of the spinner controls. Numerical results showed favorable correlation in terms of composite failure modes on the spinner cone, and the secondary impact fracture of the controls components such as upper spoke and cyclic link. The validated analytical model is used as a design support tool to produce useful information on the load mechanisms to guide the program for redesign.

• Birdstrike onto the Composite Intake of a Turbofan Engine

  Marco ANGHILERI,Luigi CASTELLETTI, Fabio INVERNIZZI, Marco MASCHERONI - Politecnico di Milano, Italia

  Birdstrike is a menace for flight safety likely to have tragic consequences. In view of that, the efforts provided to design high-efficiency bird-proof structures are fully justified. In this work the impact of a standard 4-lb bird onto a nacelle made of composite material required for the certification of the component has been investigated using LS-Dyna 970. Initially, the dynamic behaviour of the composite material used in the manufacturing of the external skin panels of the intake was achieved by referring to specific experimental tests. It was observed, in fact, that the dynamic behaviour of the composite material has a deep influence on the failure mechanism of the structure. Subsequently, the numerical model worked out for the composite material was used to numerically reproduce a bird impact certification test. A SPH model of the bird validated in previous research was used. A good numerical-experimental correlation between experimental data and numerical results was obtained.

• bjective evaluation of the quality of the FAT ES-2 dummy model

  Christian Gehre - PDB, Sebastian Stahlschmidt - DYNAmore GmbH, Matthias Walz - DAIMLER AG

  The numerical simulation is an essential part of the development of the passive safety of vehicles. Robust and predictable computational models are the base of the successful application of those simulations. Crash test dummies and their virtual counterparts are measuring tools to evaluate the injury risks to occupants in car crashes. The progress of those dummy models was remarkable over the past years. By increasing the quality, the potential of further significant improvements declines. Hence, the assessment of im- provements and their impact on the overall quality of simulations is getting more complex. Major improvements of sub-parts do not necessarily improve the overall performance of a model. There- fore, a standardised objective evaluation of models could ease the definition of priorities of model updates. Objective rating tools could help to solve this problem. These tools are calculating the level of correlation between two signals, usually coming from test and simulation. All signal ratings can be merged to global ratings. However, the analysis of only one loading case is not sufficient to calcu- late a reliable and a robust quality score of a dummy model. A more comprehensive approach is required to provide a valid rating for all relevant loading conditions. Furthermore, it must distin- guish between good and poor models and should correlate with user experiences. This paper presents results of a study to assess the quality of the LS-DYNA FAT ES-2. The data set comprises results of dummy certification tests as well as results of various component and sled tests. The extraction of the most relevant dummy responses was an essential part of the evaluation too. Finally, all scenarios were applied to different releases of the FAT ES-2. The cal- culated quality scores were verified with the experiences of users of the model. The findings of this study are limited to the FAT ES-2 model but can be transferred to another dummy model. However, the selection of loading cases and signals must be adjusted to each dummy.

• Blast Detonated by Impact Simulation

  M. Büyük (Sabanci University), H. Balaban, U. Penekli (FE-Tech)

  The purpose of this study is to present parameters required for blast detonated by impact simulation in LS-DYNA with comprehensive approach and compare with AUTODYN results. Blast detonated by impact is a widely used method for controlled blast. However, design of the problem is more likely limited to simulation results. For a proper and reliable simulation, it has to be taken care of reacted and unreacted state parameters of detonative product, mesh size and method.

• Blast Impact on Aluminum Foam Composite Sandwich Panels

  Rajan Sriram, Uday K. Vaidya - The University of Alabama at Birmingham

  Sandwich aluminum foam structures are being considered for energy absorption applications, crashworthiness, protection of transformer housings, and structural safety. Blast loading is one such phenomenon that is a potential threat to such structures. This study examines LS-DYNA modeling for aluminum foam sandwich composites subjected to blast loads. The sandwich composite was designed using polymer composite facesheets and aluminum foam as core. The core was modeled using material model 126 (*MAT_MODIFIED_HONEYCOMB). The facesheets were modeled using material model 59 (*MAT_COMPOSITE_FAILURE_SOLID_MODEL) and material model 161 (*MAT_COMPOSITE_MSE). 1 point corotational solid element formulation was used for the core and constant stress solid element formulation was used for the facesheets. LS-DYNA implementation of CONWEP blast equations (*LOAD_BLAST) was used to apply the blast load. The box design was evaluated using simulation and iterated until similar performance was achieved. The results were used to predict the modes of failure and energy absorption phenomenon. The simulation was also performed for different dimensions of box having different curvatures. The paper discusses details of the LS-DYNA simulation work and the parametric studies for the aluminum foam sandwich constructions.

• Blast Mitigation Seat Simulations Using LS-DYNA®

  Buğra Balaban, Ahmet Mete Sabah

  Military vehicles are exposed to mine and explosive loads in operational conditions and the vehicle must have the appropriate protection level to prevent personnel injuries. Blast mitigation seats represent a critical component in ensuring personnel safety. In this study, we conducted mine blast simulations using the non-linear finite element code LS-DYNA® to examine the structural behavior of blast mitigation seats. The blast simulations were carried out in accordance with the requirements of NATO AEP-55 STANAG 4569 VOL-2. We employed the Structured Arbitrary Lagrangian-Eulerian (ALE) method for these simulations. The model encompassed an ALE domain, including soil, air, explosive definitions, and a Lagrange domain for the 4x4 military vehicle. To assess the impact of the explosive charge on the occupant, we utilized the LSTC Hybrid III 50th dummy. We measured force and acceleration outputs from the dummy and compared them with the allowable limits defined in NATO AEP-55 STANAG 4569 VOL-2.

• Bolted Joint Connections of FRP-Components in Submarines Subjected to Underwater Shock

  A. Rühl, B. Özarmut, B. Hennings, O. Nommensen, A. Paul (thyssenkrupp Marine Systems)

  The application of fiber reinforced plastic (FRP) and sandwich components is an established practice at various locations in state-of-the-art submarines. Due to acoustic reasons, easy formability and low mass density at comparatively high strength values, these components bear a huge potential for buoyancy-related constructions. The shock-design and -calculation of these components as well as their connecting parts are crucially supported by Finite Element simulations using LS-DYNA. The present work shows an investigation of FRP-based bolted joint connections in today’s submarines and their connection to the pressure hull in terms of modelling and simulation. The transfer from detailed models to simulation of a full-scale shock submarine, as shown in Fig. 1, is presented and discussed.

• Bolted Joint Representation in LS-DYNA to Model Bolt Pre-Stress and Bolt Failure Characteristics in Crash Simulations

  Shailesh Narkhede, Nitin Lokhande, Bhavesh Gangani, Ganesh Gadekar - Tata Motors Ltd.

  During the vehicle crash event (especially vehicles involving light and heavy commercial vehicles where bolted connections are predominantly used) bolted joints behavior, in terms of deformation and failure, play significant role in detecting the level of occupant protection offered by the vehicle structure. The current FE modeling techniques, for bolted joint representation in crash FE models, pose various limitations in terms of simulating the real life bolted joint behavior with explicit codes like LS-DYNA. The present bolt modeling techniques do not address the important aspects of bolted joint like • pre-load/pre-stress representation in the bolt, • bearing stresses between bolt shank and clamped plates, clamping forces between plates • Friction between bolts and plates and failure modeling of bolting joints. This paper describes FE modeling methodology, for bolted joint representation in crash FE models, for crash simulations using LS-DYNA. Two alternative options are proposed for modeling of bolted joint, either with beam element or with solid hexa elements so as to address the above mentioned aspects of bolted joint in crash simulations. The proposed FE modeling methodology is validated with theoretical calculations and experimental test results. The proposed bolt modeling methodology will help to achieve accurate prediction of structural behavior in crash load cases where bolted joints are predominantly used in crash load paths, such as cabin structure assessment with pendulum impacts, assessment of under run protections devices etc.

• Book of Abstracts.pdf
• Book of Abstracts.pdf
• Boundary Element Analysis of Muffler Transmission Loss with LS-DYNA

  Z. Cui, Y. Huang (LSTC)

  This paper presents a case study of applying the boundary element method (BEM) in LS-DYNA for calculating transmission loss (TL) of mufflers. Both the three-point method and the four-pole transfer matrix method are used for calculating the transmission loss. The three-point method is easier to use, but it solves for the transmission loss only and nothing else. The four-pole method has the advantage of providing transfer matrix of the muffler, which contains important parameters when the muffler is connected to another muffler or other components in the silence system. Numerical predictions are examined by experimental results and theoretical results for all test cases. The results show that LS-DYNA can be used to perform muffler transmission loss analysis effectively.

• Breaking Bad(ly) – Investigation of the Durability of Wood Bats in Major League Baseball using LS-DYNA®

  Eric L. Ruggerio, James A. Sherwood and Patrick J. Drane (University of Massachusetts)

  The bats used in Major League Baseball (MLB) are turned from a single piece of wood. Northern white ash had been the wood of choice until the introduction of hard rock maple in the late 1990s. Since the introduction of maple, there has been a measurable increase in the number of bats breaking into multiple pieces. These failures can be a significant factor during play, i.e. pieces of bats landing flying into the field of play, thereby distracting fielders from making the appropriate play for the given game situation. Observations of bat breakage in the field and in controlled conditions of lab testing of bats have shown the bat durability is a function of wood quality and bat profile. Wood quality is described by the density and the slope of grain of the wood. The bat profile is described by the variation in the diameter of the bat along its length. The bat properties that are preferred by players, i.e. low-density wood and a bat profile of a big barrel and a slender handle, are in direct contradiction with what makes for a durable bat. In this paper, LS-DYNA is used to develop calibrated models of the breaking of yellow birch wood bats in controlled lab conditions. The WOOD material model in combination with the ADD EROSION option using a maximum principal strain failure criterion was found to produce a credible simulation of the failure modes seen in wood baseball bats.

• Brick versus shell elements in simulations of aluminium extrusions subjected to axial crushing

  Ø. Fyllingen - Bergen University College, O.S. Hopperstad, A.G. Hanssen, M. Langseth - Norwegian University of Science and Technolog

  In previous published literature, deviations in the mean crushing force and deformation pattern have been found between simulations with plane stress shell elements and experimental results for aluminium extrusions subjected to axial crushing. In the current study, simulations with solid and shell element models were carried out and compared to experimental results to study the influence of element type for this class of problems. The mean crushing force in the simulations using shell elements with through thickness stretch and solid elements were much closer to the experimental values than the plane stress shell elements. Concerning the deformation pattern, the solid element simulation exhibited a folding pattern much closer to the experimental one than the simulation with plane stress shell elements. To validate the conclusions drawn here, simulations of profiles with other geometries should be performed and compared to experimental results.

• Brick versus shell elements in simulations of aluminium extrusions subjected to axial crushing

  Ø. Fyllingen - Bergen University College, O.S. Hopperstad, A.G. Hanssen, M. Langseth - Norwegian University of Science and Technolog

  In previous published literature, deviations in the mean crushing force and deformation pattern have been found between simulations with plane stress shell elements and experimental results for aluminium extrusions subjected to axial crushing. In the current study, simulations with solid and shell element models were carried out and compared to experimental results to study the influence of element type for this class of problems. The mean crushing force in the simulations using shell elements with through thickness stretch and solid elements were much closer to the experimental values than the plane stress shell elements. Concerning the deformation pattern, the solid element simulation exhibited a folding pattern much closer to the experimental one than the simulation with plane stress shell elements. To validate the conclusions drawn here, simulations of profiles with other geometries should be performed and compared to experimental results.

• Broad-Spectrum Stress and Vibration Analysis of Large Composite Container

  Adrian Jensen, George Laird (Predictive Engineering, Inc.), Adrian Tayne (ECS Case, Becklin Holdings, Inc.)

  A large composite shipping container was analyzed for drop, impact, PSD random vibration and general stress analysis. The main shell of the container was a glass-fiber vacuum infused composite with closures made of aluminum. Lifting rings and other major structural load points were attached to the composite container using thick aluminum plates with preloaded bolts to distribute point loads into the shell. The uniqueness of this work was that one base model could address progressive composite failure whether under static conditions (implicit) or during drop test analysis (explicit) along with bolt preload and extensive nonlinear contact behavior at closures, skid plates and load rings. Analysis recommendations are provided for general implicit analysis for: (i) PSD random vibration with bolt preload; (ii) progressive failure of composites with *MAT_54; (iii) contact modeling and (iv) optimization of run times using MPP LS-DYNA ® . The explicit analysis of the container was rather simplistic but some comments will be made about the analysis setup and runtimes.

• Buckling and post-buckling analyses of stiffened composite shells with inter-laminar damages

  Aleksandrs Korjakins, Patricia Kara, Kaspars Kalnins - Technical University, Riga

  In the present paper buckling and post-buckling response of axially loaded composite stiffened shell with inter-laminar damage regions have been solved using computer code LS-DYNA. Reduced number of layers and reduced stiffness in damaged region has been investigated. In addition skin delamination with contact model has been used for the analysis of the fracture toughness in the damaged regions. Energy release rates are calculated by Technique-B methodology, employing the 2D shell elements. Mode I and mode II fracture properties are obtained in the damaged regions of the carbon/epoxy composite stiffened shell. The influence of different damages regions on the buckling and post-buckling behavior of stiffened shell is investigated.

• Buried Charge Engineering Model: Verification And Validation

  Len Schwer (Schwer Engineering & Consulting Services), Todd Slavik (LSTC)

  Livermore Software Technology Corporation (LSTC) recently added an empirically-based model for buried mine blast loading via the keyword *INITIAL_IMPULSE_MINE. This is an engineering model based upon experimental results, much like the air blast engineering model provided by *LOAD_BLAST_ENHNACED. The model is based on the work of Westine, et al. (1985) as presented, and extended, by Tremblay (1998). The implementation is applicable to flat (horizontal) and oblique (angled) target plates consisting of either shell or solid elements. Westine, et al. (1985) performed a series of buried charge experiments using thick (non-deforming) target plates with a set of impulse plugs inserted into holes drilled in the plate. The impulse plugs were spaced at 10 different ranges from the plate center, and hence angles from the center of the buried charge. Detonation of the buried charge forces the impulse plugs vertically out of the plate and measurement of their speed provides an estimate of the momentum (impulse) provided by the buried charge.

• CAD-integrated Untrimmed Body-fit Unstructured Spline LS-DYNA Preprocessing for Isogeometric Analysis and Digital Twins

  William W. Charlesworth, Richard H. Crawford, Daniel L. Keller, Benjamin Urick

  Isogeometric Analysis (IGA) has emerged as a next generation advancement in the field of Computer-Aided Engineering (CAE) and simulation thanks to its ability to utilize geometric representations native to Computer-Aided Design (CAD) models. Ansys LS-DYNA®’s proven capabilities for IGA have made it the premier solver for the technology. While the direct benefits for analysis are well documented, industrial adoption has been hampered by the difficulty in producing IGA-ready models from CAD data. Trimmed multi-patch IGA preprocessing approaches have seen advances at the industrial level but the desire for untrimmed body-fit unstructured splines has remained an unsolved approach in IGA preprocessing. In this paper, we discuss an IGA preprocessor for Ansys LS-DYNA® that not only produces untrimmed body-fit unstructured splines but does so in a process that is integrated directly into a CAD application.

• CAE Analysis of Passenger Airbag Bursting through Instrumental Panel Based on Corpuscular Particle Method

  Y. Feng, M. Beadle (Jaguar Land Rover)

  The safety regulation requires that passenger airbag (PAB) to deploy into working position in time without causing any fragmentation of its surrounding structure. Due to the significant load of airbag deployment and its complex unfolding process, it is always a challenge to design a PAB system which enables airbag safely bursting through instrumental panel. A CAE based approach has been developed at Jaguar Land Rover (JLR) to lead the passenger airbag system design. The foundation of the CAE approach is to model the airbag bursting loading condition representatively.

• CAE Applications for Balanced Curtain Airbag Design Meeting FMVSS226 and System/Component Performance

  Bill Feng (Jaguar Land Rover)

  Curtain airbag is a key restraint component to protect occupants in the events of side impact (referred as First Impact) and rollover (referred as Second Impact). In the curtain airbag design during the vehicle programme, following requirements dominate the design. FMVSS226 Ejection Mitigation (EjM) requires curtain airbag provide adequate protection for rollover event. Restraint system performance for legal and consumer tests, such as FMVSS214 and NCAPs, requires good occupant head protection in the first impact. TWG Out-Of-Position (OOP) requires low risk deployment of curtain airbag for the occupants seating in out-of-position. In addition, curtain airbag design should ensure the integrity of surrounding trims, such as pillar trims, during the deployment at different environmental conditions. In 2011, NHTSA introduced the new regulation for rollover protection, FMVSS226 Ejection Mitigation. The requirement demands increased occupant containment in rollover and side crashes for belted/unbelted occupants and third rows of seating. The rule requires the linear impact tests at two energy levels and two inflation times (e.g. 278J@1.5s and 178J@6s). The results of this requirement are the introduction of larger curtain airbag with higher power inflator for longer inflation. Since then, FMVSS226 EjM has become a key loadcase to define the curtain airbag inflator selection and curtain airbag design. However, the introduction of larger curtain and larger inflator has great challenge to the integrity of curtain airbag and surrounding trims, and OOP performance as well. Therefore, it is important that balanced performances between restraint system requirements and component requirements during the process of curtain airbag design and inflator selection. In this paper, CAE applications and studies have been conducted to gain the understanding of energy requirements and managements for balanced curtain design airbag to meet the multiple requirements on restrain system performance, EjM, OOP and component integrity.

• CAE as a Service as Cloud Platform for the Full LS-DYNA Simulation Process

  A. Geiger, K.-H. Hierholz, C. Neimöck (T-Systems)

  Mit CAE as a Service stellt T-Systems eine Cloud-basierte Lösung für den gesamten CAE Prozess vom Infrastruktur- bis zum Softwarelayer mit dynamisch skalierbarem Durchsatz und Leistungsfähigkeit. Use cases sind u.a. (a) HPC Spitzenlastabdeckung für Durchsatz- und Problemgrößen-Peaks, (b) Bereitstellung des vollständigen CAE Prozesses mit Pre-/Solver-/Postprocessing und Simulation Data Management als Service, (c) Bereitstellung von sicheren und skalierbaren Kollaborationsumgebungen für die gemeinsame Entwicklungsarbeit zwischen OEM und OES.

• CAE Correlation with Test for Door Slam in Nonlinear Dynamic Stress and Fatigue Life Analysis

  Guangtian Gavin Song, Rana Sanghera, Surya Yerva, Hamid Keshtkar - DaimlerChrysler Corporation

  In automotive industry, CAE fatigue life analysis is very important in durability evaluation and product optimization to dramatically reduce the design period and minimize the expensive durability testing. In the past time, CAE fatigue life analysis is constrained to the linear stress based methodology in the local strain approach. Generally, the linear stress based methodology is stress analysis with linear material properties. Contact surface could be defined if needed for large deformation and rotation dynamic problem. Then, the stress time history result is retrieved to input to further fatigue life analysis or firstly converted to nonlinear stress with Neuber’s rule with considering plastic deformation effect. But in some cases, the structure’s large deformation and rotation movement can make large area plastic deformation. Under those cases, the linear stress based methodology can’t precisely predict the load path, and further affect the following fatigue analysis accuracy. Nonlinear dynamic method with material nonlinearity should be used in stress prediction for those cases, and the principal strain time history retrieved from nonlinear stress analysis can be directly input to fatigue analysis. This investigation takes door slam as example with LS-DYNA as solver in both the linear and the nonlinear methodology based stress analyses and with Fe-Fatigue in fatigue life analyses to show the linear stress based methodology more conservative and the nonlinear stress based methodology more accurate together with strain life method for low cycle fatigue in nonlinear dynamic problem.

• CAE Data Management and Quality Assessment of LS-DYNA Crash Models using V-CESS

  Matthias Eick, Dr. Lars Fredriksson, Dr. Jochen Seybold - Altair Engineering GmbH

  The meshing, modeling and evaluation of LS-DYNA crash models for vehicle crash simulations is constantly subjected to an increase in complexity, since the model sizes grow, several vehicle variants are instanced from one single CAE data set and since the number of load cases and the requirements on the evaluation quality are constantly increasing. Current models sometimes contain more than 1000 different components and 1 million elements. In recent years, the model complexity has also been increased since interior parts and dummy models are included. The increased complexity makes it difficult to handle the models since changes in parts in many cases influence many different vehicle variants and load cases. V-CESS is a "Virtual Process Automation Framework" designed to simplify and standardize this type of CAE processes and is developed together with DaimlerChrysler AG, department PBE/DAM [3]. The system was developed in a pilot project with the aim to manage the CAE data of the "Sprinter Successor" in order to create, manage and evaluate crash models in LS-DYNA. In engineering projects together with DaimlerChrysler AG, department PBE/DAM, we have shown that the return on investment of V-CESS is reached at about 1.5 virtual prototypes. The meshing cost can be reduced by 15% and the engineering cost saving is approx. 30%.

• CAE Data Management from a single Geometry Revision to multi-disciplinary Simulation Results

  Jens Philippeit, Zoran Petrovic - Siemens Product Lifecycle Management Software

  Development processes for more complex new products and better performance require necessarily verification through digital simulation. Due to shortened development cycles the time to answer questions about reliable product characteristics is cut off and an efficient change management has to be established in the process chain from CAD to CAE. Normally CAE processes start with CAD data from a PDM system. To start CAE analysis it is required to easily filter different product configurations from latest CAD data, automatically prepare data for simulation (i.e. batch meshing) and pass this to simulation processes. Depending on type and number of simulations and change rate of CAD it will be shown what tools a simulation data management system can provide to efficiently guide the CAE process and shorten the cycles between CAD and CAE. Optimized data handling as well as integration of CAE tools will be the key for synchronized and economic development processes. Making decisions on digital simulations mostly involves different simulation disciplines. Therefore decisions for digital optimizations have to run in a multi-disciplinary context, access the same data sources and lead to a common decision of all involved analysis. By establishing a Simulation Data Management this can be done very efficiently keeping the data together and running as fast as possible a decision making process. Tools like workflows and decision tables will support this process.

• CAE Data Management from a single Geometry Revision to multi-disciplinary Simulation Results

  Jens Philippeit, Zoran Petrovic - Siemens Product Lifecycle Management Software

  Development processes for more complex new products and better performance require necessarily verification through digital simulation. Due to shortened development cycles the time to answer questions about reliable product characteristics is cut off and an efficient change management has to be established in the process chain from CAD to CAE. Normally CAE processes start with CAD data from a PDM system. To start CAE analysis it is required to easily filter different product configurations from latest CAD data, automatically prepare data for simulation (i.e. batch meshing) and pass this to simulation processes. Depending on type and number of simulations and change rate of CAD it will be shown what tools a simulation data management system can provide to efficiently guide the CAE process and shorten the cycles between CAD and CAE. Optimized data handling as well as integration of CAE tools will be the key for synchronized and economic development processes. Making decisions on digital simulations mostly involves different simulation disciplines. Therefore decisions for digital optimizations have to run in a multi-disciplinary context, access the same data sources and lead to a common decision of all involved analysis. By establishing a Simulation Data Management this can be done very efficiently keeping the data together and running as fast as possible a decision making process. Tools like workflows and decision tables will support this process.

• CAE Process Support by MIDAS and MEDINA

  Sattler M., Finkel A.

• CAE Simulations for Passive Safety focused on the Porsche Cayenne - the Transition to New Technologies

  Erich Schelkle, Herbert Klamser - Dr. Ing. h.c. F. Porsche AG

  Simulation technologies are methods which have been traditionally applied in automotive engineering for a long time. Over the decades, enormous progress has been achieved in both, the simulation methods and the CAE-programs used. Thanks to the high efficiency levels of the current computer generation and the use of economically priced commercially available hardware such methods are being applied on a widespread basis today. Visionary concepts of the past are turning into reality. When considering the process of automotive engineering and the futuristic potential inherent in those methods, it becomes obvious that virtual automotive development still is in its infancy. This applies to the whole range of options from the coupled parallel/sequential simulation of manufacturing processes to the cross-functional simulation, including efficient management systems designed to handle the entire CAE process [1]. At the same time, the CAE model transfer between the various expert departments on the one hand and between the OEMs and the system suppliers on the other has to be optimized while developing suitable documentation- and DataMining systems [2]. What must also be mentioned is the need for continuous updating of the traditional methods in terms of numerical data and technical content. Currently, in the early phases of automotive engineering, the development activities are mostly handled in a sequential manner [3,4]. That is where the newly conceived CAD/CAE methods come in quite handy: They allow component geometries to be prepared on the basis of topologies and parameters and subsequent modifications to be implemented quite rapidly [5]. For the synergy effects of these innovative design tools to be made full use of it is necessary, however, to combine the parametric concept geometry model with mathematical optimization methods. This approach allows the inherent design potential to be fully opened up and thus the defined targets to be reached in the most optimum way [6]. Even though such numerical design strategies have already been used in certain areas, their wide-spread and consistent introduction into conceptual design is yet to come. It is with these innovative CAD/CAE strategies that the present paper is dealing.

• CAE Validation Study of a Side Window Impact using Plexiglas Materials

  D. Lopez Ruiz (Tecosim Technische Simulation), A. Rühl, Prof. S. Kolling (THM Giessen), E. Ruban, B. Kiese­wetter, S. Ulzheimer (Evonik Industries)

  An experimental and numerical study regarding the head impact on a side rear window was performed. Based on several years of material development and manufacturability (Evonik Industries AG), the expert knowhow in material testing and LS-DYNA material implementation (Giessen Institute of Mechanics and Materials) and the CAE user experience (TECOSIM Technische Simulation GmbH) and in closer cooperation between all parties, it was decided to start a development study. The outcome of the study should show the behavior of different PLEXIGLAS® (PMMA) windows using different PLEXIGLAS® grades and possible feasible combinations.

• CAE Workflow Coupling Stamping and Impact Simulations

  Henry Shibayama, Rohit Ramanna, Sri Rama Murty Arepalli, Arthur Camanho (ESI)

  Visual-Environment is an open and integrated user environment enabling simulation and analysis across multiple domains for efficient product engineering. A CAE workflow has been developed chaining stamping and impact simulations. The workflow originates from stamping matrix design (performing stamping simulations) to impact simulations considering the residual stress and thickness variation due to stamping process. The objective to be achieved is the creation of a fast end-to-end workflow, aiming at accurate impact simulations while taking into account the results from manufacturing processes. So far, impact simulations are performed considering the stamping simulation results. The next step of the project is to perform welding simulations and consider its residual stresses and distortion, aiming at more accurate impact simulations, through chaining and considering the process effects coming from stamping and welding analysis as well. Visual-Diemaker is a software tool focusing on the design of the stamping matrix, with some feasibility tools, such as tipping evaluations. Visual-Diemaker also integrated some tools for the set-up of stamping simulation. For development and evaluation of the methodology all simulations were performed using PAM-STAMP. Generated output results were M01 files (one per component), containing the residual stress and thickness variation. In a first step Visual-Process, a mass-customization and automation tool to support the automation of CAE tasks, converts automatically M01 (PAM-STAMP) file structure to LS-DYNA® key-words respectively syntax (using ELEMENT_SHELL_THICKNESS and INITIAL_STRESS_SHELL). As a second step, the same tools allows the CAE engineer to open the LS-DYNA impact model in Visual-Environment, then setting the components to be chained with the stamping results, define the reference nodes for the construction of a reorientation matrix, and finally define a different number of integration points through the thickness. This process basically reads and converts the M01 syntax and also adds the INCLUDE_STAMPED_PART syntax into the global impact model which references the converted M01 file. The purpose of the project is the ability of automated chaining between manufacturing and performance structural simulation in one and same environment. After achieving this development goal, further implementation and industrialization of this kind of analysis methodology into a CAE industrial department is expected as a reliable and fast way to proceed with chained analysis using different CAE solver.

• Calculating Electromagnetic Field (EMF) Distortion to Maintain and Secure Electric Transmission Lines

  John Puryear, David Rodriguez (ABS Consulting), Iñaki Çaldichoury (Livermore Software Technology Corporation)

  Critical to the electric power grid are the high voltage transmission lines. These assets are geographically dispersed and typically transverse large distances across remote areas. Those attributes make them challenging to maintain and physically secure. Electrical power system operators are continually improving data acquisition and interpretation to draw new inferences about system performance. These advances raise the possibility of monitoring the power lines’ electromagnetic fields (EMFs) and using them as “sensors” with a range of potential applications. One possible application is ballistic detection. A common problem for utilities is ballistic damage to insulators. Were reliable ballistic detection available, inspection could be triggered by actual gunshots and restricted to where gunshots occurred. With growing concern of attacks to the power grid, being able to detect gunsh ots is additionally attractive. A bullet passing near a power line is a conductor passing through a large EMF. This physical condition raises the possibility that a change in the line signal could be detected when a bullet passes near the cable. LS-DYNA ® ’s electromagnetic (EM) solver was used to calculate the change in line signal due to a bullet passing nearby. Another potential application of power lines as sensors is structural health monitoring. Transmission lines themselves are conductors within a baseline EMF. Displacements caused in service conditions (galloping conductors or damaged insulators) or by extreme events (seismic damage or high winds), change the mutual inductance between the cables. This scenario served as a second case study for calculating the effect of an external event (kinematic motion of cables) on the cable signal. Finally, metal theft or willful damage is a persistent threat to utility assets, and the capability of sensing and identifying the location of an intruder anywhere along the line would assist in apprehending the intruder and deter future intrusions. In principle, the power line can function like existing electromagnetic devices that sense intrusion. This possibility was investigated using the EM solver. Specifically, a finite element model including an energized transmission cable and intruding truck has been used to calculate any change in cable current density due to the presence of the truck. In this paper, the motivation for analyzing these case studies, the details of the studies themselves and results from the calculations are presented. In addition, recommendations for future work are discussed.

• Calculation and Validation of Material Tests with Specimens Made out of Filled Elastomers

  P. Thumann, K. Swidergal, Prof. M. Wagner (OTH Regensburg)

  In deep-drawing dies for steel sheet parts of car bodies huge masses are moved. To prevent vibrations, which occur by sudden acceleration or stopping of those masses, elastomeric tubular dampers [1] are used. The dampers are made out of carbon filled elastomers. A good knowledge about the material behaviour of metals is available.

• Calculation of the Velocity and Shape of an Explosively Formed Projectile (EFP) Using Axisymmetric ALE

  John Puryeara, Ben Harrison, ABS Group, 140 Heimer Rd. Suite 300, San Antonio, TX;, Lynsey Reesec, Michael Oesterle, NAVFAC Engineering and Expeditionary Warfare Center, Port Hueneme, CA

  The symmetry common to most explosively formed projectiles (EFPs) permits their characterization using 2D axisymmetric analysis. Formation of an EFP entails volumetric expansion of the explosive and extensive plastic flow of the metal plate, both of which can be calculated using an Arbitrary Lagrangian Eulerian (ALE) method. Accordingly, the 2D axisymmetric ALE capability in LS-DYNA® was applied to calculate the velocity and shape of an EFP. The methodology was validated against EFP velocity and shape measurements published in SAND-92-1879 by Hertel.

• Calibration and Application of GISSMO and *MAT_258 for Simulations Using Large Shell Elements

  Joakim Johnsen, Jens Kristian Holmen (Enodo AS), Gaute Gruben (SINTEF Industry), David Morin, Magnus Langseth (Norwegian University of Science and Technology (NTNU)

  For many industrial applications finite element (FE) models are becoming increasingly large, making shell elements a necessary tool to maintain a reasonable computational time. Shell elements describe a plane stress state and phenomena like local necking and failure under bending must be appropriately dealt with. Thickness-to-length ratios larger than two are not uncommon for shell elements. This is often larger than the elements used for material model calibration and can sometimes lead to challenges in describing the geometry and the stress state. In this study, we evaluate the accuracy of *MAT_258 and a standard GISSMO calibration. The material and component tests are made of Docol 1400M. Results from *MAT_258 and GISSMO are compared to several component tests spanning a wide range of stress states.

• Calibration and Experimental Validation of LS-DYNA Composite Material Models by Multi Objective Optimization Techniques

  Stefano Magistrali - Omega Srl, Research and Innovation Centre, Marco Perillo - EnginSoft SpA

  Experimental quasi-static tensile and impact tests were conducted over two different types of composite laminates and four different types of sandwich laminates, in order to evaluate their basic mechanical characteristics and energy adsorption capability. The second phase of this research work approaches and resolves the calibration of the mechanical parameters included into the LS-DYNA composite material models. This calibration starts and is based on the material physical properties derived from the test results. LS-DYNA model parameters, model constrains and objectives defining the problem have been studied and analysed by using modeFRONTIER. modeFRONTIER is a multi-objective and multi-disciplinary integrated platform. Input parameters were varied into a controlled range. This allows to find quickly and to define accurate model configuration as well as model sensitivity to those parameters, leading to reliable numerical models for impact simulations. Accurate comparison of simulation results with experimental material results is crucial to achieve optimum and precise material models. The present research study offers also an understanding of the effect of numerical input parameters and variables on sandwich laminates structural response in terms of absorbed energy, maximum energy, maximum force and curve morphology. Calibration of material models, able to reproduce the effective impact behaviour of real composite materials, is fundamental in order to simulate general crashworthiness problems. This kind of approach allows either to understand variable influences on composite dynamic structural response or to get improved solution for industrial case studies.

• Calibration of *MAT_258 with a Lode dependent fracture surface and its application in bending of high-strength steel

  J. Holmen, J. Johnsen (Enodo), D. Morin, M. Langseth (NTNU)

  *MAT_258 (*MAT_NON_QUADRATIC_FAILURE) is a through-thickness failure regularization model for shells in LS-DYNA. In this model the failure indicator is computed as a function of both the size of the element and its bending-to-membrane loading ratio. The constitutive behavior and fracture surface in *MAT_258 are represented by well-known analytical expressions which simplify calibration. We present the calibration process for *MAT_258 with a three-parameter Extended Cockcroft-Latham fracture surface for the high strength steel Docol 1500M. The material card is applied in shell element simulations of three-point bend tests.

• Calibration of GISSMO Model for Fracture Prediction of A Super High Formable Advanced High Strength Steel

  Xiaoming Chen, Guofei Chen, Lu Huang, Ming F. Shi, United States Steel Corporation

  Advanced high strength steels (AHSS), due to their significantly higher strength than the conventional high strength steels, are increasingly used in the automotive industry to meet future safety and fuel economy requirements. Material failure that was rarely observed in crash tests a decade ago occurs more frequently in AHSS parts due to the relatively low ductility when compared to conventional steels. In computer aided engineering (CAE) crash analysis, a fracture model is often integrated in the simulations to predict the effects of material failure during crash events. In this paper, parameters of a fracture criterion are generated and calibrated for a Super High Formable (SHF) Steel with a minimum tensile strength of 1180 MPa (1180SHF).

• Calibration of Material Models for the Numerical Simulation of Aluminium Foams – MAT 154 for M-PORE Foams @ 3 Loads

  Vito Primavera, Marco Perillo (EnginSoft SpA), A. Carofalo, M. De Giorgi, R. Nobile (University of Salento)

  Metallic foams are very promising for engineeristic applications due to their peculiar characteristics, like the high energy-absorbing property coupled with a reduced weight. Even if applications can be widespread in several fields, such as automotive, civil, aerospace, etc., industrial requirements are still far to be fully accomplished, especially in terms of technological processes and a whole mechanical characterization. Material modeling of metallic foams, like the aluminium ones, is a crucial point for performing accurate numerical simulations along with the design phase. Material models available in the explicit, non-linear finite element code LS-DYNA® represent a very efficient way to handle and to investigate foam behavior. An extended experimental/numerical activity has been set out at the aim to calibrate and validate suitable material models with respect to different aluminium foams and several loading conditions. While a previous phase of the activity [1] has been focused on the assessment of a procedure addressed to point out, starting from the available experimental data, the key points of material model calibration, the current activity has been focused on the procedure application, i.e. the exploitation of the built-up methodology in respect of calibration of M-PORE open cells aluminium foam at three different loading conditions. A good number of foams material models are available in the LS-DYNA database, and further in the last years different enhancements have been performed at the goal to include the physical phenomenons able to increase the accuracy of the models. Amongst the available ones, MAT 154 (MAT_DESHPANDE_FLECK_FOAM) has been here chosen because it provides satisfactory results compared with the experimental ones, but at the same time it still requires to be studied for more loading conditions. Since the calibration process requires to optimize the material model free parameters according to different objectives, LS-DYNA has been coupled with modeFRONTIER®, Process Integration and Design Optimization software platform. Once all the FE (Finite Element) models related to the corresponding experimental tests have been integrated into modeFRONTIER, a first sensitivity analysis has been performed at the purpose to get confidence with MAT 154 behavior and then an efficient optimization phase in order to pursue the numerical configurations satisfying the different targets provided by experimental tests. Efficient and intuitive post-processing tools have been applied firstly to get a deep knowledge of the investigated phenomenons and eventually to look for the best solutions.

• Calibration of Six Constitutive Material Models for Geomaterial

  R. Nasouri (University of Texas), H. Rokhy (Amir Kabir University), A. Matamoros, A Montaya (University of Texas), R. Backzadeh (Urmia University)

  Recently, several constitutive material models have been developed and added to the LS-DYNA library to predict concrete geomaterial behavior. These developments were established merely from using concrete compressive strength, which limits the level of robustness in capturing actual concrete behavior. This study focuses on developing a simplified approach to calibrate six constitutive material models including Soil and Foam, Pseudo Tensor, Geological Cap Model, Concrete Damage Model Rel-3, Johnson Holmquist, and Continues Surface Cap Model against Triaxial and Hydrostatic Compression Tests (TXC and HCT) data. Comparisons between individual numerical results were performed to evaluate whether accuracy can be offered through a corresponding constitutive material model. The presented calibration method can also be applied to different geomaterials such as rock and soil.

• Capabilities of Result Visualization in LS-OPT V4.1 - Demonstrated by Means of Industrial Problems

  Katharina Witowski, Heiner Müllerschön - DYNAmore GmbH

  During the last decade the optimization software LS-OPT has been used for design optimization, for DOE-studies, for system identification and for stochastic investigations in many industrial projects. LS-OPT became over the years a highly sophisticated software tool with very effective and reliable optimization methodologies particular suitable for highly nonlinear problems. This paper illustrates the capabilities of LS-OPT by means of several industrial applications. The focus is on the new post processing features of LS-OPT 4.1 such as visualizing results of multi-objective optimization, multiple load case optimization, sensitivity analysis and the visualization of curve data evaluated on the basis of meta-models. Of course, the objective and the setup of the optimization problems is discussed and demonstrated.

• Car Body Optimization Considering Crashworthiness, NVH and Static Responses

  Phani Adduri, Gary Quinn, Juan P. Leiva, Brian C. Watson (Vanderplaats Research and Development, Inc)

  This paper demonstrates a design system to efficiently perform optimization based on responses computed from multiple LS-DYNA® analyses while also taking into consideration the linear loading conditions such as the ones for NVH and Static responses. The proposed design system, ESLDYNA, is based on the Equivalent Static Load (ESL) method, which requires the iterative process of non-linear structural analysis (LS-DYNA) and linear structural analysis and optimization (GENESIS). Unlike general purpose optimization software packages, it does not require a large number of analysis calls even for problems with large numbers of design parameters. Therefore, large-scale optimization techniques, such as topology, topometry and topography, can be easily employed. Several examples using different optimization techniques will be presented. One of the examples will include optimizing the design for frontal crash, normal modes and static loading conditions simultaneously.

• Cardiac Electrophysiology Using LS-DYNA®

  Pierre L’Eplattenier, Iñaki Çaldichoury, Facundo Del Pin, Rodrigo Paz, Attila Nagy, Dave Benson (Livermore Software LLC)

  Heart disease is among the leading causes of death in the Western world; hence, a deeper understanding of cardiac functioning will provide important insights for engineers and clinicians in treating cardiac pathologies. However, the heart also offers a significant set of unique challenges due to its extraordinary complexity. In this respect, some recent efforts have been made to be able to model the multiphysics of the heart using LS-DYNA. The model starts with electrophysiology (EP) which simulates the propagation of the cell transmembrane potential in the heart. This electrical potential triggers the onset of cardiac muscle contraction, which then results in the pumping of the blood to the various organs in the body. The EP/mechanical model can be coupled with a Fluid Structure Interaction (FSI) model to study the clinically relevant blood flow parameters as well as valves or cardiac devices. This paper concentrates on the EP part of the model. Other papers in this conference will present the mechanical and FSI parts. Different propagation models, called “mono-domain” or “bi-domain”, which couple the diffusion of the potential along the walls of the heart with ionic equations describing the exchanges between the inner and the outer parts of the cells have been implemented. These models were first benchmarked against published results obtained from other EP research codes on a simple cuboid heart tissue model. More recently, we also performed benchmarks proposed by the FDA against analytical solutions. Other features of the EP solver will also be presented such as coupling between the tissue and a surrounding bath, coupling between mono and bi-domain in the same model, and coupling of the mono/bi domain models with a Purkinje Network. Finally, multi-physics simulations with the EP coupled with mechanical deformation and FSI for the blood flow will be presented. These models include arteries and valves for a realistic model of a ventricular pump.

• Cardiac Electrophysiology using LS-DYNA®

  Pierre L’Eplattenier, Sarah Bateau-Meyer, Dave Benson, Livermore Software Technology Corporation, Livermore, California 94551;, Vikas Kaul, Carl Schu, Mark Palmer, Darrell Swenson, Joshua Blauer, Medtronic plc, Minneapolis, Minnesota 55432

  Heart disease is among the leading causes of death in the Western world; hence, a deeper understanding of cardiac functioning will provide important insights for engineers and clinicians in treating cardiac pathologies. However, the heart also offers a significant set of unique challenges due to its extraordinary complexity. In this respect, some recent efforts have been made to be able to model the multiphysics of the heart using LS-DYNA.

• Cardiac Electrophysiology using LS-DYNA®

  P. L’Eplattenier, I. Caldichoury, K. El Houari (Ansys/LST)

  Heart disease is among the leading causes of death in the Western world; hence, a deeper understanding of cardiac functioning will provide important insights for engineers and clinicians in treating cardiac pathologies. However, the heart also offers a significant set of unique challenges due to its extraordinary complexity. In this respect, some recent efforts have been made to be able to model the multiphysics of the heart using LS-DYNA.

• CASE STUDY – Material models for depiction of unloading in low speed crash applications

  B. Hirschmann, Y. Nakagawa, N. Matsuura (Honda), H. Pothukuchi, M. Schwab (4a engineering)

  Computer simulation is used in many fields of automobile development to shorten the development term and reduce tests. Large plastic parts such as instrument panels and bumper fascia take a lot of time to make a die, so it is necessary to determine the part shape quickly to shorten the term. Therefore, performance verification by simulation is important. However, due to issues such as material property and complicated part shapes, reproduction of phenomena such as deformation and failure are sometimes not sufficiently accurate in simulations of plastic parts. Creating a die, testing part, and evaluating its performance in such a situation may raise the possibility of inadequate performance. In that case, it is necessary to modify the die, which requires extra cost and time. Therefore, high simulation accuracy is necessary to avoid such risks.

• Cause Investigation of Capsizing Accident of Ro-Ro Ferry Ship using Marine Accident Integrated Analysis System

  S. Lee, J. Lee, J. Park, T. Jung (Korea Maritime & Ocean University)

  Ro-Ro Ferry ship was capsized and was sunk down to the bottom in the sea water due to the rapid turning for the several reasons, such as lack of stability and poor lashing, etc. Objective of this study is to investigate the capsize accident cause by full-scale ship rapid turning simulation through the comparison with AIS track in this capsize accident, considering several factors, such as GoM, ship velocity, rudder angle, etc., and using Marin Accident Integrated Analysis System (highly advanced M&S system of FSI analysis technology). MAIAS of full-scale ship turning simulation are verified by comparison with maneuvering performance sea trial test result of initial building ship. Several things were carried for this rapid turning simulation, such as accurate ship model modification using floating simulation according to hydrostatic characteristics of loading conditions, and investigation of cargo loading arrangement and cargo lashing states. There was relatively good agreement of full-scale ship sea trial turning simulation with sea trial test result, and good prediction of cargo loading arrangement and cargo lashing states comparing to the AIS track in this capsize accident.

• Cause Investigation of Flooding & Sinking Accident of Ro-Ro Ferry Ship using Marine Accident Integrated Analysis System

  S. Lee, J. Lee, J. Park, T. Jung (Korea Maritime & Ocean University)

  Ro-Ro Ferry ship was capsized and was sunk down to the bottom in the sea water due to the rapid turning for the several reasons, such as lack of stability and poor lashing, etc. Objective of this study is to figure out the air pocket existence in the flooding & sinking accident using Marin Accident Integrated Analysis System (MAIAS; highly advanced M&S system of Fluid-Structure Interaction analysis technology). Several things were carried for this investigation of air pocket existence, such as accurate ship posture track according to accident duration using several accident photos and movies, precise ship and cargo moving track and sea water inflow amount according to accident duration using floating simulation and hydrostatic characteristics program, accurate understanding of exterior openings and interior paths of sea water inflow, simulation of sea water inflow using flooding & sinking simulation and calculation of exterior openings & interior inflow paths. There was relatively good prediction of air pocket existence.

• Ceramic-rubber hybrid materials – A way to sustain abrasive heavy impact applications

  M. Herr (AC2T research), M. Varga, L. Widder (AC2T), J. Mermagen, S. Rodinger, W. Harwick (Fraunhofer EMI)

  Transport of raw materials in industrial applications usually involves highly abrasive processes and requires wear protection for a reliable, long operation period. At transfer points such as between conveyer belts additional impact loads can limit the lifetime. For such conditions rubber-ceramic hybrid materials can extend the lifetime multifold by combining the wear resistance of ceramics with the impact resistance of rubbers.

• Certification by Analysis of a Typical Aircraft Seat

  N. Dhole, V. Yadav, G. Olivares (National Institute for Aviation Research)

  Advancements in computer hardware in recent years have made it possible to solve complex real world problems using finite element methods (FEM). Full scale dynamic certification testing of aircraft seats is a very complex, expensive and time consuming process. A high acceleration pulse is applied on the seat structure in a short duration of period, and the seat structure has to pass stringent FAA certification criteria. FAA and the aircraft industry are working together to reduce the cost and time required for certification of the seat while improving occupant safety. This is being achieved by using a process known as Certification by Analysis or CBA where the seat is certified using finite element methods. The process and guidelines for CBA are described in advisory circular AC 20-146 developed by the FAA. As per the AC 20-146, FE models can replace the actual dynamic testing scenarios such as: 1) demonstrating compliance to standard test requirements for changes to a baseline seat design, 2) establishing the critical seat installation/configuration in preparation for dynamic testing. This paper describes in detail different techniques that can be used for the validation of a FE model of typical aircraft seat using the finite explicit code LS DYNA. As an example, the FE model of an aircraft seat is validated against the full scale dynamic test conducted as per AC 25.562.

• CFD Validations with FDA Benchmarks of Medical Devices Flows

  Chien-Jung Huang, Iñaki Çaldichoury, Facundo Del Pin, Rodrigo R. Paz, LSTC

  Computational Fluid Dynamics (CFD) is a powerful tool and has been applied on various problems. In the biomedical application, CFD has been applied not only on the simulations of blood flow and airflow in lungs, but also on the designs and analysis of the medical devices. This study focuses on two benchmark problems proposed by FDA for the standardization of CFD simulation on the safety analysis on the blood-contacting medical devices, which is called CFD Round Robin study. The first case is the flow in a nozzle with a conical change in diameter at one end of the throat, and a sudden change at the other end, whereas the second problem is the system of blood pump housing and impeller. These two problems were simulated with the LS-DYNA® ICFD solvers and the obtained results are compared with results from other numerical and experimental studies.

• Challenges of Predicting Impacts with Roadside Safety Hardware: Recent Case Studies

  Akram Abu-Odeh, Texas A&M Transportation Institute, The Texas A&M University System College Station, Texas

  As an integral part of engineering safer roads, road side safety devices passively interact with errant vehicles to redirect them safely back to the road or bring them to a safe and controlled stop. These devices take the form of crash cushions, cable barriers, concrete barriers, steel barriers, guardrails, guardrail terminals and others. Placement criteria and warrants are established in the AASHTO Road Side Design Guide (1). However, before those devices are placed on the roadways, they have to be evaluated under objective test conditions. Given that possible combinations of impact speeds, impact angles, vehicle characteristics and roadway characteristics are infinite, it is impossible to design roadside safety hardware for all those combinations. Thus a “Practical Worse Case” philosophy derived from crash data analyses is followed to determine such impact conditions. In the USA, the evaluation methodologies are established in the Manual for Assessing Safety Hardware (MASH) guidelines (2). As with any design process, gone are the days of try and error experimentation due to increased cost of testing and the increased accuracy and efficiency of simulation. Hence, state of the art nonlinear finite element methodology has been gaining tractions in designing and enhancing the safety of roadside devices. LS-DYNA® established itself as the code of choice for simulating vehicular impact scenarios with roadside hardware. This paper will highlight roadside safety hardware (3, 4) that was designed through extensive LS-DYNA simulations and had subsequent crash tests per the latest MASH guidelines. Signals and phenomena from simulations are compared with those from the subsequent tests and presented within this paper.

• Challenges of Simulative Consideration of Aluminium Hardening Caused by Paint-Bake

  David Koch, André Haufe, Christoph Wilking, Christian Liebold (DYNAmore GmbH), Markus Feucht, Sebastian Roller (Mercedes-Benz AG)

  Local pre-straining in the forming process and thermal loading in the paint bake process have a significant effect on the further development of local material properties. In many cases it is therefore unavoidable to take such effects into account in the further course of the simulation along the part processing chain. This is particularly evident when the hardening of aluminium components during artificial ageing in the cathodic dip painting furnace is to be considered. During the precipitation processes, dislocations form between the metal lattices depending on the pre-straining and the applied temperature load, which ultimately lead to a further increase in strength. In the following it is shown how this strengthening can be estimated for use in subsequent CAE simulation processes and thus made accessible to crashworthiness simulations. The basis for this approach is the JMAK equation that describes the degree of local hardening phenomenologically. Tensile tests are carried out on differently pre-strained and heat-treated samples. Based on the results of the tests the parameters of the JMAK equation are derived. Using *MAT_TAILORED_PROPERTIES in LS-DYNA® allows the consideration of several locally varying state variables. Here the yield stresses are to be defined as a function of i.e. the degree of hardening and the pre-strain applied during the forming process. The corresponding quantities are mapped from the discretization of the forming simulation (i.e. equivalent plastic strains) and the thermal simulation of the paint-bake-oven (i.e. the computed degrees of hardening) onto the spatial discretization used in crashworthiness. Thus, it is possible to represent the dependence of the yield curves on the decisive influencing variables of the production and hence consider locally individual material behaviour.

• Characterisation and Simulation of Structural Adhesives

  M. Clarke, J.G. Broughton, A.R. Hutchinson - Oxford Brookes University, M. Buckley - Jaguar Land Rover

  The analysis of adhesive bonded joints and structures relies on accurate materials data and mathematical models. In the present study the goal was to develop a method for simulating accurately, using LS-Dyna, the behaviour of aluminium structures bonded with a single part, heat curing epoxy adhesive. This required a structure with known boundary conditions and for which the substrates deformed in a predictable manner. A suitable specimen, formed from two folded aluminium tubes bonded into a T-shape, had been developed by Ford Research Center, Aachen. The MAT 169 material card was selected as a method that showed promise for use in the simulation of bonded joints. A test programme was developed to characterise the adhesive for use with the MAT 169 material card, using tests from the British Standards catalogue. These data were then used to analyse the T-shaped structure under quasi static loading. The results of tests and analysis of the T-shaped structures were used to assess the accuracy of the adhesive characterisation and suitability of the MAT 169 material card. A parametric study was then carried out to determine the robustness of the solutions. Once it had been established that a robust solution had been reached the results from the parametric study were used to develop an optimised set of input data for the adhesive.

• Characterisation and Simulation of Structural Adhesives

  M. Clarke, J.G. Broughton, A.R. Hutchinson - Oxford Brookes University, M. Buckley - Jaguar Land Rover

  The analysis of adhesive bonded joints and structures relies on accurate materials data and mathematical models. In the present study the goal was to develop a method for simulating accurately, using LS-Dyna, the behaviour of aluminium structures bonded with a single part, heat curing epoxy adhesive. This required a structure with known boundary conditions and for which the substrates deformed in a predictable manner. A suitable specimen, formed from two folded aluminium tubes bonded into a T-shape, had been developed by Ford Research Center, Aachen. The MAT 169 material card was selected as a method that showed promise for use in the simulation of bonded joints. A test programme was developed to characterise the adhesive for use with the MAT 169 material card, using tests from the British Standards catalogue. These data were then used to analyse the T-shaped structure under quasi static loading. The results of tests and analysis of the T-shaped structures were used to assess the accuracy of the adhesive characterisation and suitability of the MAT 169 material card. A parametric study was then carried out to determine the robustness of the solutions. Once it had been established that a robust solution had been reached the results from the parametric study were used to develop an optimised set of input data for the adhesive.

• Characterisation of an Energy Absorbing Foam for Motorcycle Rider Protection in LS-DYNA

  S. Maier (University of Stuttgart), M. Helbig (DYNAmore), H. Hertneck (SAS-TEC), J. Fehr (University of Stuttgart)

  A study on traffic fatalities [1] shows that the most frequent causes of motorcyclists’ deaths in accidents are multiple skeletal and visceral injuries. Brain and skull injuries are the second leading cause. An injury frequency and pattern data analysis of discharged riders of powered two-wheelers from hospitals [2] show that the most common injuries of non-fatal accidents are injuries of the lower extremities followed by upper extremity and traumatic brain injuries. With this data of fatal and non-fatal accidents it can be said that besides head protection, the protection of a two-wheeler rider’s whole body with lower and upper extremities is of major importance.

• CHARACTERIZATION AND COMPONENT LEVEL CORRELATION OF ENERGY ABSORBING (EA) POLYURETHANE FOAMS (PU) USING LS-DYNA MATERIAL MODELS

  Babushankar Sambamoorthy - Lear Corporation

  Polyurethane (PU) foams are one of the most widely used countermeasures for head impact protection. For accurate prediction of the head injury parameters, studies were conducted to establish a reliable LS-DYNA[1] material model to characterize PU foams. A 5.0pcf (80.09 g/l) PU foam was characterized using four different material models available in LS-DYNA for simulating foams, namely MAT_LOW_DENSITY_FOAM (MAT57), MAT_CRUSHABLE_FOAM (MAT63), MAT_BILKHU_DUBOIS_FOAM (MAT75) and MAT_FU_CHANG_FOAM (MAT83)[1]. The Finite Element Analysis (FEA) results were compared with the physical test results. The FEA material model resulting from the characterization procedure was validated using a component level, head impact correlation study. A simple side rail section was extruded about the SR1 target point and was impacted with a standard headform at an initial velocity of 15mph. Three different cases were investigated; baseline model with body-in-white (BIW) only, BIW with 18mm foam and BIW with 22mm foam. The Head Injury Criterion (HIC)[2] and acceleration curves from the simulation were compared with the physical tests.

• CHARACTERIZATION AND COMPONENT LEVEL CORRELATION OF ENERGY ABSORBING (EA) POLYURETHANE FOAMS (PU) USING LS-DYNA MATERIAL MODELS

  Babushankar Sambamoorthy, Tuhin Halder - Lear Corporation, Ford Division

  Polyurethane (PU) foams are one of the most widely used countermeasures for head impact protection. For accurate prediction of the head injury parameters, studies were conducted to establish a reliable LS-DYNA[1] material model to characterize PU foams. A 5.0pcf (80.09 g/l) PU foam was characterized using four different material models available in LS-DYNA for simulating foams, namely MAT_LOW_DENSITY_FOAM (MAT57), MAT_CRUSHABLE_FOAM (MAT63), MAT_BILKHU_DUBOIS_FOAM (MAT75) and MAT_FU_CHANG_FOAM (MAT83)[1]. The Finite Element Analysis (FEA) results were compared with the physical test results. The FEA material model resulting from the characterization procedure was validated using a component level, head impact correlation study. A simple side rail section was extruded about the SR1 target point and was impacted with a standard headform at an initial velocity of 15mph. Three different cases were investigated; baseline model with body-in-white (BIW) only, BIW with 18mm foam and BIW with 22mm foam. The Head Injury Criterion (HIC)[2] and acceleration curves from the simulation were compared with the physical tests.

• Characterization and Material Card Generation for Thermoplastics

  M. Helbig, A. Erhart, A. Haufe (DYNAmore GmbH)

  Modelling polymer materials for crashworthiness applications is still an ongoing and challenging topic. Besides the constitutive model the spatial discretization plays a significant role in setting up predictive models in impact scenarios where damage and fracture are dominating the part deformation. Therefore, the limits of the chosen spatial discretization shall always be kept in mind. However, the present contribution is focused on recent enhancements of constitutive models for polymeric materials. This topic is as well ongoing for many years and has been tackled almost 2 decades ago by the development of MAT_SAMP-1 (#187) in LS-DYNA®. Many years of continuous improvement lead to a versatile and usable as well as predictive model. Unfortunately for the cost of slow execution speed if the parameter set or the various curve definitions were not chosen wisely. Therefore, a simplified model with the aim to have a more competitive model available when it comes to computing speed was developed. The so called SAMP_LIGHT (#187L) model comes with a complete redesign for speed but also with a number of limitations (due to the speed argument) and still seems to be versatile enough for everyday simulations. The present contribution recalls the features of SAMP-1 and discusses some of the issues that may lead to exaggerated execution time. Then the reduced model is described and a viable approach to convert available SAMP-1 constitutive data towards SAMP_LIGHT is presented. Clearly the limited model may not be as predictive as the fully flavored one – but the drawbacks may not be severe enough to not give it a try.

• Characterization and Modeling of the Deformation and Failure Behavior of Neat Thermoplastic Homopolymers under Impact Loading Conditions

  P. Stelzer, Z. Major (Johannes Kepler University Linz)

  The increasing use of thermoplastic polymers in structural applications exposed to impact loading conditions drives the need of accurate and reliable FEM simulations. Classical elasto-plastic formulations are based on the von Mises yield criterion and only of limited suitability for modeling polymers. Advanced material models become necessary to capture the complex mechanical deformation and damage behavior. However, the experimental effort is significantly higher to provide material input data. The objective of this study was the modeling of the deformation and damage behavior of thermoplastic homopolymers under monotonic and impact loading conditions with the commercial FEM code LS-Dyna. For this purpose, the material model SAMP-1 and the damage model GISSMO were employed for a Polypropylene and a Polycarbonate grade. A comprehensive experimental characterization, applying full-field strain analysis using a digital image correlation technique and a high speed camera, was performed for the calibration of the models. To derive the input parameters for SAMP-1, uniaxial tensile and simple shear tests were carried out. Experimental compression data was taken from previous studies. Coupon tests were conducted to assess the triaxiality dependent damage and failure behavior. The focus was set on the methodology and modeling techniques to identify a suitable calibration method for the constitutive models. To describe the actual local deformation behavior and to provide a straight-forward methodology, a direct experimental approach was favored to derive the material model input data. Validation was performed on the tensile tests by comparing the numerical and experimental results of the global force-displacement curves and of the local deformations. The elasto-viscoplastic constitutive model SAMP-1 was calibrated for ambient temperature (23±1 °C) and three different strain rates (0.1, 1 and 10 s−1). Until the yield point is reached, the mechanical response is linear elastic. The characteristic pressure dependent quadratic yield surface of SAMP-1 was fitted by the input of tensile, compression and shear data. Moreover, the model incorporates multiaxial hardening behavior. The non-isochoric plastic deformation could be captured by the experimentally determined apparent Poisson’s ratio. The determination of the failure curve, in terms of failure strains as a function of the stress triaxiality factor, is essential for the calibration of ductile damage models like the formulation implemented in SAMP-1 or GISSMO. A combined experimental-numerical approach was used to identify equivalent plastic strain values and corresponding stress triaxiality factors at fracture initiation. A case study on the calibration of a GISSMO model by numerical optimization was conducted for an aluminium alloy. The method of an average triaxiality factor was selected as a rather direct way to extract the failure strains from the experimental tests and was applied for PP and PC.

• Characterization and Modeling of Spot-Weld Joints in Press Hardening Steels Associated with Softening in Heat Affected Zone

  H. Ghassemi-Armaki, Q. Khan (ArcelorMittal); A. Gill, S. Zilincik (Chrysler)

  Next generation of advanced high strength steels (AHSS) are extensively considered for usage in Body-in-White (BIW) with lower thickness to reduce the vehicle weight and increase fuel efficiency. Resistance Spot Welding (RSW) continues to be a major joining process in BIW, with an average of 4500 spot-welds per vehicle. Spot-weld strength has direct correlation with the thicknesses, and yield strength of the joining sheets in the stack up configuration. Characterization and FEA modeling of spot-welds for accurate failure prediction is of vital importance in vehicle crash safety simulations. This will also lead to an optimized weld layout, optimum weld pitch and cycle time and this has a direct impact on assembly plant layout/investment. Press Hardening Steels “PHS” (e.g. Usibor® 1500) show high strength after hot-stamping and are one of the major category of AHSS. These steels contain a fully martensitic microstructure, which show softening in Heat Affected Zone (HAZ) after spot-welding because of martensite tempering. Accurate prediction of load-displacement and failure load of the spot-weld depends on input data for softened HAZ and connection definition of two joining sheets. In the present study, a modeling method for the spot-weld nugget and HAZ zone was developed and compared to test results. An eight, hexahedral element assembly is used to represent a spot-weld and an element ring of width, 0.35 times of the weld diameter is used to simulate softened HAZ. Since softening in the HAZ is not uniform and shows a gradient as a function of distance from spot-weld center, the HAZ material simulated using Gleeble for different locations was used to characterize and provide material input data for the HAZ shell element. Spot-weld failure was characterized by testing the spot-weld in different loading modes, including, tension-shear, coach-peel, cross-tension and KSII configurations (30, 60 and 90 degrees). *MAT_100_DA in LS-DYNA (version 9.1) was used along *DEFINE_CONNECTION_PROPERTIES for defining material properties for the weld. Results show that the chosen stress-strain curve representative for HAZ shell elements extracted from Gleeble samples can predict the yielding of the load-displacement curve well. Additionally, *MAT_100_DA parameters depend on sheet metal thickness, and exponents for failure equation in this model can be lower than 1 and up to 4 as reported in literature.

• Characterization and Modeling of Spot-Weld Joints with *MAT_100_DA Parameter Optimization using LS-OPT®, and 3 Sheet Spot-weld Modeling Method Development in LS-DYNA®

  Qaiser Khan, Hassan Ghassemi-Armaki, ArcelorMittal Global R&D, East Chicago, IN, USA;, Amandeep Singh Gill, Scott Zilincik, FCA Chrysler Technical Center, Auburn Hills, Michigan, USA;, Abhishek Gawade, Purdue University, Indianapolis, Formerly Intern at ArcelorMittal

  Spot-weld strength is of crucial importance to the overall vehicle structural integrity and crash safety. With the innovation of Advanced High Strength Steels (AHSS), prediction of spot-weld fracture is of paramount importance in current and future vehicle designs. Spot-weld testing on AHSS intensive coupons was carried out in five different loading conditions, such as Tension-Shear, Coach-Peel, Cross-Tension and KSII configurations (30, 60 and 90 degrees). In spot-weld simulation, a combination of an eight element hexahedral assembly and *MAT_100_DA was used for defining the spot-weld failure criteria. *MAT_100_DA is a 3D stress-based failure surface model which requires the user to define failure stress and exponents for axial, shear and bending stress in order to fail a spot-weld nugget. These parameters are generated from the coupon testing performed in different loading conditions and has to be done for each individual spot-weld stackup in the vehicle.

• Characterization and Modeling of Engineering Friction and Wear with LS-DYNA

  S. Dong (Ohio State University); A. Sheldon (Honda)

  In mechanical systems, friction and wear usually take place concurrently between two surfaces when they slide or roll relative to each other. Friction exhibits resistance to the relative motion which may vary with different normal loads and relative velocities, while wear is the removal and displacement of the materials from one or both surfaces. The initiation of significant surface wear, in turn, changes the friction, and therefore the overall contact properties. This occurs more often when there are differences in hardness and/or surface roughness between the two surfaces. This paper presents experimental characterization of friction and surface wear between different material combinations. Materials tested, from hard to soft, include coated steel, plastics, ATD rubber, and roof linear fabric. Static and dynamic friction coefficients are measured using a pin-on-disc tribometer under various normal loads and linear velocities. Surface wear, if significant, is characterized using an optical profilometer or a microscope. It was found that the friction coefficient decreases when surface wear first takes place. Part of the displaced material gets stuck in between the two surfaces and acts as a third-body solid lubricant. This type of lubrication mechanism plays more significant role when the material opposite to the worn material is harder. The modeling of friction and wear is then implemented in LS-DYNA. The relationship between friction coefficients, normal stress, and linear velocity is defined in *CONTACT and the wear properties are defined in *CONTACT_ADD_WEAR. Parametric studies are then performed to study the influence of wear and friction properties in crash models.

• Characterization of a cohesive zone model for adhesives with *MAT_240 and curve mapping method in LS-OPT

  Nicole Betz, Tobias Behling, Martin Holzapfel, Mathieu Vinot, Nathalie Toso

  The importance of adhesives in automotive structures exposed to high crash loads has increased over the years. To improve the structural sizing, it is necessary to predict the behavior of bonded joints under dynamic impact and crash loads. Cohesive zone models have proven to be suitable for numerically representing adhesive behavior in Finite-Element simulations. However, the manual determination of the model parameters requires experience with the material model and a corresponding amount of time to derive the various parameters. The present work aims at developing an optimization scheme with LS- OPT for the effective and automated identification of input parameters for the material card *MAT_240 (*COHESIVE_MIXED_MODE_ELASTOPLASTIC_RATE) [1] which is used to represent the behavior of the adhesive layer. The present work focuses on a curve mapping process with LS-OPT.

• Characterization of fragments induced by High Velocity Impacts and additional Satellite shielding protective structures evaluation

  T. Legaud, V. Lapoujade (DynaS+)

  A substantial number of debris coming from human production gravitates around the Earth. Their size, nature, orbit and velocity can extremely vary, but all these debris represent an increasing collision risk and a threat for the current and future spatial activity. The spatial researchers are looking for solutions to limit this risk, by better controlling the launched objects number and by improving the protection of their structures.

• Characterization of the Lode = -1 Meridian on the Al-2024 Failure Surface for *MAT_224 in LS-DYNA ®

  Robert L. Lowe, Jeremy D. Seidt, Amos Gilat (The Ohio State University)

  A key ingredient in the modeling of ductile fracture using *MAT_224 in LS-DYNA is the failure surface, a 3-D graphical representation of the equivalent plastic strain at failure as a function of stress triaxiality and Lode parameter. Ballistic impact experiments used to validate the existing *MAT_224 plasticity and failure models for 2024 aluminum reveal a strong trend of ductile fractures along the Lode = -1 meridian, a region currently underpopulated with experimental data. Exploiting a novel physical interpretation of the Lode = -1 meridian, several new experiments to populate this critical region are proposed and numerically simulated in LS-DYNA, based on adaptations of the standard ASTM quasi-static hemispherical punch test.

• Characterization of Water Impact Splashdown Event of Space Shuttle Solid Rocket Booster Using LS-DYNA

  Matthew E. Melis - NASA Glenn Research Center, Khanh Bui - Livermore Software Technology Corporation

  The ALE capability in LS DYNA is used to predict splashdown loads on a proposed replace- ment/upgrade of the hydrazine tanks on the thrust vector control system housed within the aft skirt of a Space Shuttle Solid Rocket Booster. Two preliminary studies are preformed in working towards conducting a full comprehensive analysis: An analysis of the proposed tank impacting water without supporting structure, and an analysis of actual space capsule water drop tests conducted at NASA’s Langley Research Center. Results from the preliminary studies provide confidence that useful predictions can be made by applying the ALE methodology to a detailed analysis of a 26-degree section of the skirt with proposed tank attached. Results for all three studies are presented and compared to limited experimental data. The challenges of using the LS DYNA ALE capability for this type of analysis are discussed.

• Characterizing LS-DYNA ® Implicit performance on SGI ® Systems using SGI MPInside MPI profiling tool

  Dr. Olivier Schreiber, Tony DeVarco, James Custer, Scott Shaw (SGI)

  SGI delivers a unified compute, storage and remote visualization solution to manufacturing customers reducing overall system management requirements and costs. LS-DYNA integrates several solvers into a single code base. The implicit solver is studied for better matching with the multiple computer architectures available from SGI, namely, Multi-node Distributed Memory Processor clusters and Shared Memory Processor servers, both of which are capable of running in Shared Memory Parallelism (SMP), Distributed Memory Parallelism (DMP) and their combination (Hybrid) mode. The MPI analysis tool used is SGI MPInside featuring customary communication profiling and "on the fly" modeling to predict potential performance benefits of the different upgrades available from the latest Intel ® Xeon ® CPU, interconnect and its middleware, MPI library, and the underlying LS-DYNA source code. Profile-guided MPIplace component is used to minimize inter rank transfer times.

• Characterizing LS-DYNA Performance on SGI Systems using SGI MPInside MPI Profiling Tool

  T. DeVarco, O. Schreiber, A. Altman, S. Shaw (Silicon Graphics)

  SGI delivers a unified compute, storage and remote visualization solution to manufacturing customers reducing overall system management requirements and costs. LS-DYNA integrates several solvers into a single code base. In this paper, the explicit solver is hereby studied for better matching with the multiple computer architectures available from SGI, namely, multi-node Distributed Memory Processor clusters and Shared Memory Processor servers, both of which are capable of running in Shared Memory Parallelism (SMP), Distributed Memory Parallelism (DMP) and their combination (Hybrid) mode. The MPI analysis tool used is SGI MPInside.

• Chemically Reactive Flows in Airbag Inflator Chambers

  Chemically Reactive Flows in Airbag Inflator Chambers, K. Im, G. Cook Jr., Z. Zhang (LSTC)

  Airbags are part of an important vehicle safety system, and the inflator is an essential part that generates a specific volume of gas to the airbag for a short duration of time. Recently, we have developed numerical models of automotive airbag inflators in conjunction with the LS-DYNA® chemistry solver. In this study, detailed and comprehensive descriptions for theoretical models are developed for a conventional pyrotechnic inflator (PI) and a compressed, heated gas inflator (HGI).

• Classification-based Optimization and Probabilistic Analysis Using LS-OPT®

  Anirban Basudhar, Imtiaz Gandikota, Livermore Software Technology Corporation, Livermore CA, USA;, Katharina Witowski, DYNAmore GmbH, Germany

  LS-OPT is a standalone Design Optimization and Probabilistic Analysis package with an interface to LS-DYNA® that is capable of solving a variety of reliability assessment and single or multi-disciplinary design problems. It consists of a flexible framework with various methods that are suited to specific types of problems. The solution methods in LS-OPT are broadly categorized as direct or metamodel-based. Metamodel-based methods build approximations of the system responses using only a few samples, before applying core optimization or probabilistic analysis methods on these inexpensive surrogate models. They are particularly attractive due to higher efficiency compared to direct methods, which on the contrary can be prohibitively expensive in some scenarios.

• Classification-based Optimization and Reliability Assessment using LS-OPT

  A. Basudhar, I. Gandikota, N. Stander (LSTC), A. Svedin, C. Belestam (DYNAmore Nordic), K. Witowski (DYNAmore)

  Simulation-based design often involves the use of metamodeling techniques that provide a cheap surrogate model to replace expensive evaluations. Several types of metamodels are available in LS-OPT, e.g. Radial Basis Function Networks, Feed Forward Neural Networks, Kriging etc.

• Closing the Gap between Process- and Crash Simulation for Composite Materials

  Ch. Liebold, A. Haufe (DYNAmore GmbH, Germany), H. Finckh (Deutsches Institut für Textil- und Faserforschung Denkendor, Germany), T. Günther(Volume Graphics GmbH, Germany)

  The usage of fiber reinforced plastics (FRP) becomes more and more important in the automotive industry and therefore, the requirements for accurate crash analysis results for such materials increase. As already known from sheet metal forming, process simulations are performed to predict fiber orientations for all kinds of short, long or endless fiber reinforced parts, even though most of the available software tools only use geometrical approximations. On the example of carbon reinforced braided tubes, a mapping tool will be introduced which is able to transfer fiber orientations as well as initial stresses and strains gained from braiding simulations using a high resolution beam mesh onto a coarse crash mesh. The mapping results will be compared with CT–scans taken from such tubes to confirm their accuracy. In the near future, the developed mapping algorithm shall support all kinds of process simulations such as draping or weaving for different element types as well as for different composite materials.

• Cloud-based Pedestrian Protection App

  Megha Seshadri, Naga Prasad Lagisetty, ESI Group

  Democratize as the meaning says “make (something) accessible to everyone,” is the main objective of today’s industry to have simulations accessible to everyone to achieve significant improvements in development time and consistent outputs. In this paper we would like to present the workflow of a cloud-based Pedestrian Head Impact simulation. The Head Impact simulation will be executed through an embedded workflow, which internally executes several existing and validated process templates on cloud. Once the process execution is completed, the results are uploaded to the cloud and made available for download and visualization on the web.

• Cloud-Enabled CAE Solutions: Requirements, Basic Concepts and Usability

  A. Heine (CPU 24/7)

  Up-to-date, particularly commercial methods of numerical simulation are able to meet requirements of modern product development and optimisation processes. However, essential prerequisite is not only the application software but also the appropriate High Performance Computing (HPC) resources. Specific applications, like simulation of large models with a very high number of grid points, CFD-driven design optimisation with necessary innumerable variations as well as complex, multidisciplinary problems regarding the simulation of iterative interactive effects are typical examples of getting efficient, high-quality, prompt and precise results only through appropriate High Performance Computing.

• Cluster Scalability of Implicit and Implicit-Explicit LS-DYNA Simulations Using a Parallel File System

  Mr. Stan Posey, Dr. Bill Loewe - Panasas Inc., Dr. Paul Calleja - University of Cambridge

  The parallel efficiency and simulation turn-around times of CAE software continue to be an important factor behind engineering and scientific decisions to develop models at higher fidelity. Most parallel LS-DYNA simulations use scalable Linux clusters for their demanding HPC requirements, but for certain classes of FEA models, data IO can severely degrade overall scalability and limit CAE effectiveness. As LS-DYNA model sizes grow and the number of processing cores are increased for a single simulation, it becomes critical for each thread on each core to perform IO operations in parallel, rather than rely on the master compute thread to collect each IO process in serial. This paper examines the scalability characteristics of LS-DYNA for implicit and implicit-explicit models on up to 256 processing cores. This joint study conducted by the University of Cambridge and Panasas, used an HPC cluster environment that combines a 28 TFLOP Intel Xeon cluster with a Panasas shared parallel file system and storage. Motivation for the study was to quantify the performance benefits of parallel I/O in LS-DYNA for large-scale FEA simulations on a parallel file system vs. performance of a serial NFS file system. The LS-DYNA models used for the study comprise cases that were relevant in size and physics features to current LSTC customer practice. The favourable results demonstrate that LS-DYNA with parallel I/O will show significant benefit for advanced implicit simulations that can be heavy in I/O relative to numerical operations. These performance benefits were shown to extend to a mix of concurrent LS-DYNA jobs that require concurrent data writes to a shared file system, which for an NFS-based file system would still bottleneck from its single data path for I/O. The paper also reviews CAE workflow benefits since, as an LS-DYNA simulation is completed, the same shared storage provides a platform for direct post-processing and visualization without the need for large file transfers.

• Cluster Scalability of Implicit and Implicit-Explicit LS-DYNA Simulations Using a Parallel File System

  Mr. Stan Posey, Dr. Bill Loewe - Panasas Inc., Dr. Paul Calleja - University of Cambridge

  The parallel efficiency and simulation turn-around times of CAE software continue to be an important factor behind engineering and scientific decisions to develop models at higher fidelity. Most parallel LS-DYNA simulations use scalable Linux clusters for their demanding HPC requirements, but for certain classes of FEA models, data IO can severely degrade overall scalability and limit CAE effectiveness. As LS-DYNA model sizes grow and the number of processing cores are increased for a single simulation, it becomes critical for each thread on each core to perform IO operations in parallel, rather than rely on the master compute thread to collect each IO process in serial. This paper examines the scalability characteristics of LS-DYNA for implicit and implicit-explicit models on up to 256 processing cores. This joint study conducted by the University of Cambridge and Panasas, used an HPC cluster environment that combines a 28 TFLOP Intel Xeon cluster with a Panasas shared parallel file system and storage. Motivation for the study was to quantify the performance benefits of parallel I/O in LS-DYNA for large-scale FEA simulations on a parallel file system vs. performance of a serial NFS file system. The LS-DYNA models used for the study comprise cases that were relevant in size and physics features to current LSTC customer practice. The favourable results demonstrate that LS-DYNA with parallel I/O will show significant benefit for advanced implicit simulations that can be heavy in I/O relative to numerical operations. These performance benefits were shown to extend to a mix of concurrent LS-DYNA jobs that require concurrent data writes to a shared file system, which for an NFS-based file system would still bottleneck from its single data path for I/O. The paper also reviews CAE workflow benefits since, as an LS-DYNA simulation is completed, the same shared storage provides a platform for direct post-processing and visualization without the need for large file transfers.

• Cohesive Contact Modeling in Thermoforming Simulations of Metal-CRFP-Metal Sandwich Sheets

  Ö. Cebeci, A. Zeiser (Inpro Innovations­gesellschaft für fortgeschrittene Produk­tionssysteme in der Fahrzeug­industrie), M. von Scheven (University of Stuttgart)

  A novel carbon fiber reinforced metal laminate based on thermoplastic polymer is investigated in the project LEIKA. For the safeguarding of the production of the parts made of this material, coupled thermo-mechanical simulations have to be carried out. Experiments show a large relative sliding, separation and re-sticking behavior between layers during the forming of the heated sheets. Hence, each layer of the laminate needs to be modeled as an individual shell in order to represent the different forming behavior.

• Cohesive Zone Modeling of Adhesively Bonded Interfaces: The Effect of Adherend Geometry, Element Selection, and Loading Condition

  Devon C. Hartlen, John Montesano, Duane S. Cronin (University of Waterloo)

  Cohesive zone modeling (CZM) is an efficient technique for modeling adhesively bonded interfaces in structure-level simulations. CZM provides a reduction in computational expense compared to using solid elements and provides a more accurate representation of adhesive response, damage, and failure compared to tiebreak contact methods. Despite these benefits, the adoption of CZM is slowed, in part, due to a lack of information and guidelines as to their appropriate use in industrially relevant modeling situations. While many research studies have applied cohesive elements in conjunction with solid elements to model the adherends, most industrial applications such as automotive structures, are commonly modeled with shell elements. Using CZM to join parts meshed with shell elements requires understanding of how forces and moments are transferred from adherend to adhesive, how the bond line should be modeled geometrically, and how adhesive and adherend parts should be connected numerically. While LS-DYNA® contains several cohesive element formulations, including one specifically developed to be compatible with adherends meshed with shells, and a host of connection techniques, there remains a general lack of understanding as to how CZM should be implemented. To guide the use of CZM, a parametric study was undertaken to examine the effect of cohesive element formulation, adherend element selection, bond line geometry, adherend geometry, and the effect of various connection methods on model response. Two exemplar geometries were explored to examine the effect of different loading condition: a double cantilever beam test and a single lap shear test. It was found that changes in element selection and geometry could dramatically affect the stability and accuracy of the responses of a simulation. Based on the results of this study, this paper presents guidelines and recommended practices for applying CZM to adhesive bond lines for a range of possible modeling scenarios.

• Coil Winding Simulations of Electrical Machines

  Stavroula Stefanatou, Johannes Heydenreich

  The winding of coils on stator teeth is a central process in the manufacture of electrical machines. The quality of the windings and the associated copper fill factor are important factors for the efficiency of electrical motors. While the copper winding process was manual labor some years ago, this process has meanwhile been completely automated and has been taken over by machines and robots. What is still left for manual labor is the setup of the machines for series production. This can be quite time consuming and costly. To support this setup process, fully understand it in all its details and speed it up, BROSE has used LS-DYNA to develop simulation models for the setup of new coil windings.

• Collaboration for Future HPC-based Simulation Technologies

  A. Walser (Automotive Simulation Center Stuttgart)

  The use of Numerical Simulation and High Performance Computing (HPC) in vehicle development has already been established for years. Nowadays it is the third pillar of vehicle development along with construction and testing. Computer Aided Engineering (CAE) methods in combination with HPC technologies enable engineers to solve complex problems in a quick and cost-effective way long before hardware prototypes are available. Furthermore it opens up the possibility to analyze not just a single concept idea, but many concept variations parallel.

• Collision of a light weight passenger car against a steel bridge barrier: evaluation of severity indices varying impact conditions

  Prof. Dr. Mariano Pernetti, Dr. Salvatore Scalera - AMET ITALY

  The standards which fixes guidelines for the execution of crash tests to assess the effectiveness of safety barriers in USA and Europe, define an experiment with a low weight passenger car. Such an investigation’s aim is to evaluate risks for vehicle’s occupants in case of impact against the tested device. The congruence of this approach with the philosophy of testing at “the practical worst condition”, has been widely demonstrated in literature. On the other hand, this kind of tests are really expensive and many parameters are hard to control and measure. Due to the aforementioned reasons, numerical analysis of vehicles collisions against safety barriers has become a convenient methodology that supports and integrates the previous one, especially considering the continuous technological hardware/software progress. Besides, the chance of controlling and evaluating each factor which influences full scale crash tests, makes such a methodology an important tool to perform parametric studies to assess the influence of different factors on crashworthiness. This research, carried out with a combine numerical experimental approach, is intended to assess what happens during the collision of a light weight passenger car against a steel bridge barrier with a containment energy level of 724kJ. The work includes three parts. In the first, the fundamental steps of the modelling process are described along with any requirements needed to reproduce four different full scale tests: the frontal and oblique collisions against a concrete wall and the impacts against two types of steel barrier with different containment energy level (127kJ and 724kJ). Data comparison between full-scale and FE simulation concerns time histories of longitudinal and transversal acceleration of CG’s vehicle, ASI, THIV, PHD, pitch and roll angle, velocity variation in the vehicle direction and residual displacements of the barrier. The second part is aimed at clarifying what happens during the impact of the light weight passenger car against a steel bridge barrier. The obtained results clearly show that the acceleration of CG’s vehicle and the value of impact severity indices are affected in a meaningful manner not only by the transversal kinetic energy but also by the impact angle. The last part defines a simple procedure useful to estimate the impact severity indices for a very wide range of impact conditions. The tests performed on the procedure show a very good agreement between estimated and calculated values.

• Collision of a light weight passenger car against a steel bridge barrier: evaluation of severity indices varying impact conditions

  Prof. Dr. Mariano Pernetti, Dr. Salvatore Scalera - AMET ITALY

  The standards which fixes guidelines for the execution of crash tests to assess the effectiveness of safety barriers in USA and Europe, define an experiment with a low weight passenger car. Such an investigation’s aim is to evaluate risks for vehicle’s occupants in case of impact against the tested device. The congruence of this approach with the philosophy of testing at “the practical worst condition”, has been widely demonstrated in literature. On the other hand, this kind of tests are really expensive and many parameters are hard to control and measure. Due to the aforementioned reasons, numerical analysis of vehicles collisions against safety barriers has become a convenient methodology that supports and integrates the previous one, especially considering the continuous technological hardware/software progress. Besides, the chance of controlling and evaluating each factor which influences full scale crash tests, makes such a methodology an important tool to perform parametric studies to assess the influence of different factors on crashworthiness. This research, carried out with a combine numerical experimental approach, is intended to assess what happens during the collision of a light weight passenger car against a steel bridge barrier with a containment energy level of 724kJ. The work includes three parts. In the first, the fundamental steps of the modelling process are described along with any requirements needed to reproduce four different full scale tests: the frontal and oblique collisions against a concrete wall and the impacts against two types of steel barrier with different containment energy level (127kJ and 724kJ). Data comparison between full-scale and FE simulation concerns time histories of longitudinal and transversal acceleration of CG’s vehicle, ASI, THIV, PHD, pitch and roll angle, velocity variation in the vehicle direction and residual displacements of the barrier. The second part is aimed at clarifying what happens during the impact of the light weight passenger car against a steel bridge barrier. The obtained results clearly show that the acceleration of CG’s vehicle and the value of impact severity indices are affected in a meaningful manner not only by the transversal kinetic energy but also by the impact angle. The last part defines a simple procedure useful to estimate the impact severity indices for a very wide range of impact conditions. The tests performed on the procedure show a very good agreement between estimated and calculated values.

• Combined Analysis of LS-DYNA Crash-Simulations and Crash-Test Scans

  L. Jansen, D. Borsotto, C. Thole (Sidact)

  In robustness campaigns and optimization processes metamodels are created out of a set of crash-simulations. With the help of such analyses the models used for the simulations can be improved. For example instabilities can be found and explained or the needed material can be minimized under certain safety restrictions. An important question in this context is: How good can these metamodels represent the reality? To answer this question, one can compare the crash-simulations to the real crash-tests, which were recorded by camera systems after the crash. To be able to compare the test-data with the LS-DYNA crash-simulations, we first need to convert the test-data by matching the geometries and transferring the part information from the simulation to the crash-test. Afterwards one can calculate the combination of the simulations, which approximates geometry and deformation behavior of the test-data as close as possible. The distance and difference in behavior between this calculated best fit and the actual crash-test can be used to measure the quality of the simulation model. Once the evaluation of the model is finished, the test-data can also be added to a robustness campaign as an additional simulation and used for further analysis. This allows us to answer questions such as: How does the test fit into the simulation subspace? Which simulation runs are similar to the test for a certain crash event? Which of the dominating crash events found in the simulation can also be found in the test? Thus, the described matching procedure combined with exemplary further analysis methods on the one hand allow for a quick and automated matching between test and simulation and on the other hand a more detailed validation of the simulation model in comparison to the actual test. Due to the conversion of the test-data, the same post-processors can be used for both the simulations and the test-data, resulting in a smoother workflow.

• Combined Analysis of LS-DYNA® Crash-Simulations and Crash-Test Scans

  Dominik Borsotto, Lennart Jansen, Clemens-August Thole, SIDACT GmbH

  In robustness campaigns and optimization processes metamodels are created out of a set of crash-simulations. With the help of such analyses the models used for the simulations can be improved. For example, instabilities can be found and explained or the needed material can be minimized under certain safety restrictions.

• Combined Numerical/Experimental Approach for Rivet Strength Assessment

  F. Previtali, M. Anghileri, L.-M. L. Castelletti, A. Milanese - Politecnico di Milano

  The failure mechanism of common aeronautical structures is influenced by the crash behaviour of the riveted joints. Therefore, crashworthiness analyses of aeronautical structures require accurate models of the joints under crash conditions for a correct prediction of the crash behaviour of the structure. In this work, a method to create reliable FE models able to reproduce the behaviour of rivets under crash conditions is introduced. Using explicit FE codes, it is common practice to model rivets and bolts with rigid links or beams, and adopt as a failure criterion the allowable forces envelope obtained for a single rivet after tests [1]. It is shown here that numerical simulations of tests carried out on a single rivet under different loading conditions can be used to characterise the crash behaviour of riveted joints in place of expensive and time-consuming test campaigns. A specific test device was built in order to apply multi-axial loads to a single rivet and perform tests to evaluate the behaviour of a rivet under different loading conditions: from pure shear to pure tension. Numerical simulations of the single rivet test were then carried out using LS-Dyna [1] to reproduce experimental test and to validate the numerical model of the rivet. The rivet was discretised with solid eight-node elements and the piecewise linear plasticity material model was initially used. However, different constitutive laws were then used to characterise areas with either compressive or tensile loads. The whole loading process, from bucking to failure was simulated. Numerical results and test data were compared and it was observed that the numerical models are able to correctly represent the behaviour of a rivet after a tuning of the material parameters and therefore can be used to characterise a riveted joint. At this stage of the research, only quasi-static loading conditions were considered. This assumption allowed reducing the number of parameters that affects the calculations thus simplifying the model set-up. Future works will investigate the effect of strain rate to reproduce crash conditions.

• Combined Numerical/Experimental Approach for Rivet Strength Assessment

  F. Previtali, M. Anghileri, L.-M. L. Castelletti, A. Milanese - Politecnico di Milano

  The failure mechanism of common aeronautical structures is influenced by the crash behaviour of the riveted joints. Therefore, crashworthiness analyses of aeronautical structures require accurate models of the joints under crash conditions for a correct prediction of the crash behaviour of the structure. In this work, a method to create reliable FE models able to reproduce the behaviour of rivets under crash conditions is introduced. Using explicit FE codes, it is common practice to model rivets and bolts with rigid links or beams, and adopt as a failure criterion the allowable forces envelope obtained for a single rivet after tests [1]. It is shown here that numerical simulations of tests carried out on a single rivet under different loading conditions can be used to characterise the crash behaviour of riveted joints in place of expensive and time-consuming test campaigns. A specific test device was built in order to apply multi-axial loads to a single rivet and perform tests to evaluate the behaviour of a rivet under different loading conditions: from pure shear to pure tension. Numerical simulations of the single rivet test were then carried out using LS-Dyna [1] to reproduce experimental test and to validate the numerical model of the rivet. The rivet was discretised with solid eight-node elements and the piecewise linear plasticity material model was initially used. However, different constitutive laws were then used to characterise areas with either compressive or tensile loads. The whole loading process, from bucking to failure was simulated. Numerical results and test data were compared and it was observed that the numerical models are able to correctly represent the behaviour of a rivet after a tuning of the material parameters and therefore can be used to characterise a riveted joint. At this stage of the research, only quasi-static loading conditions were considered. This assumption allowed reducing the number of parameters that affects the calculations thus simplifying the model set-up. Future works will investigate the effect of strain rate to reproduce crash conditions.

• Combining Physical Test with Structural FEA to Develop Package-Specific Failure Models for Electronic Components

  Mike Howard, Tyler Ferris

  The use of electronics in harsh environments has increased significantly in the past few decades. For example, in automobiles, where electronic assemblies experience wide temperature extremes, temperature cycling, and shock, the cost of electronics was 18% of the total vehicle cost in the year 2000 and 40% of the total vehicle cost in 2020 [1]. Automotive electronic assemblies experience mechanical shock in a variety of scenarios such as a door slam, a vehicle crash or going over a pothole. In addition to the impact of component power dissipation on component temperatures, the automotive environment can include significant temperature variation due to diurnal solar loading, climate control, and engine heating/cooling cycles. The solder joints that connect electronic components to circuit boards are common failure locations in electronic assemblies, particularly in high shock/vibration environments and extreme temperature cycling conditions. Solder joint failure behavior is heavily influenced by the component’s package construction and materials.

• Combustion Engine Analyses Using New and Extended Features in LS-DYNA

  A. Jonsson, T. Borrvall, F. Bengzon (DYNAmore Nordic)

  Recently, many enhancements have been made to LS-DYNA’s implicit solver with regard to improved robustness and general functionality. New material models, element formulations, and features for convenient load history management all contribute to making the implicit solver more versatile and user friendly. The new features are of course relevant to general analyses, but here a case-study of a combustion engine analysis is presented to illustrate and promote these new features. Focus will be on thermal and mechanical analyses, to evaluate deformation, stress, plastic strain, gasket pressure etc. The built-in fatigue analysis capabilities of LS-DYNA will also be demonstrated since fatigue life is often the design target in structural analyses of combustion engines.

• Comparative Analysis of Occupant Responses between LS-DYNA® Arbitrary LaGrange in Euler and (ALE) and Structured–ALE (S-ALE) Methods

  Venkatesh Babu, Kumar Kulkarni, Sanjay Kankanalapalli, Bijan Khatib-Shahidi, Madan Vunnam, U.S. Army, Research Development & Engineering Command, (RDECOM), Tank Automotive Research Development & Engineering Center (TARDEC), Warren MI 48397

  The LS-DYNA ALE/FSI package can accurately model the dynamic response of the structure under blast loading. To simulate blast loading, High explosive, air and sometimes soil are modeled as different ALE materials which flow inside an ALE mesh that covers a spatial domain of our point of interest. If the spatial domain is of complex geometry, the ALE mesh is necessarily unstructured. But often times, the geometry is simply of a box shape so a structured (rectilinear) ALE mesh could be used.

• Comparative Evaluation of Isogeometric Analysis and Classical FEM with Regard to Contact Analysis

  Z. Naveed, A. Kühhorn, M. Kober (BTU Cottbus-Senftenberg)

  Isogeometric analysis represents a newly developed technique that offers the application of Computer Aided Design (CAD) concept of Non-uniform Rational B-Splines (NURBS) tool to describe the geometry of the computational domain. The simplified transition of CAD models into the computational domain eliminates the problems arising from the geometrical discontinuities induced by the faceted approximation of the mesh. Moreover, numerical analysis directly on NURBS objects significantly reduces the design-to-analysis time compared to traditional FEA approach. In the field of contact mechanics, when finite elements are applied to geometry with curved surfaces, the result is a non-smooth geometrical representation of interface surfaces which may lead to mesh interlocking, high jumps and spurious oscillations in contact forces. To eliminate these issues, various surface smoothening strategies are to be employed in case of FEM. Isogeometric based analysis alleviates these issues without employing any additional smoothening strategy due to inherent higher order continuity of NURBS basis functions and much more accurate results are obtained compared to conventional FE approach. In the current study, LS-DYNA is used to demonstrate the capabilities and advantage of an isogeometric analysis though an example of pendulum under gravitational load. The numerical simulation results are analytically validated and the comparison of NURBS surfaces with faceted surfaces is carried out to investigate the accuracy.

• Comparative Evaluation of Material Models for Crush Simulation of Cast Aluminum Alloy Wheel

  𝑌𝑢𝑤𝑎𝑟𝑎𝑗 𝑆, 𝐷𝑒𝑒𝑝𝑎 𝐴𝑟𝑖𝑔𝑎𝑙𝑎, 𝑉𝑒𝑛𝑘𝑎𝑡𝑒𝑠ℎ 𝑃𝑟𝑎𝑏ℎ𝑢 𝐶, 𝐻𝑒𝑙𝑚𝑢𝑡 𝐺𝑒𝑠𝑒, Philipp van der loos

  Wheels play a critical role in vehicle safety, especially during severe crash scenarios such as small overlap frontal impacts. In these situations, energy typically absorbed by components like bumpers and crash boxes is instead transferred directly to the wheels, which can intrude into the passenger compartment and pose severe risks to occupants. However, most of the current research related to wheels are mainly focusing on the light-weight design, next-generation material selection (HSS, AHSS, DP, etc.), wheel fatigue life improvement, and standards, such as the SAE J175 [1] lateral impact test and the SAE J3203 [2] radial

• Comparative Evaluation of Sound Absorption Performance of Various Types of Core Panels

  S. Tokura (Tokura Simulation Research Corporation)

  Core materials such as honeycomb core panels are used in various industrial products as lightweight and high stiffness materials. As one of the characteristics of the core panel, the sound absorption effect due to the core structure is expected. By using a large core panel for a soundproof wall such as a highway, the possibility of producing a soundproof wall that is lighter than the conventional soundproof wall and has a high sound insulation/absorption effect is being studied. In addition, with the electrification of automobiles, further quietness in the passenger compartment is required, and the use of core panels is being considered for improving the quietness of various transportation machines such as automobiles. Therefore, in this research, we assume several types of core shapes and compare the sound absorption effect of the core panel by modeling the interaction between the core panel and the sound in the air using ALE-based FEM in LS-DYNA®.

• Comparative Performance of InfiniBand Architecture and Gigabit Ethernet Interconnects on Intel® Itanium® 2 Microarchitecture-based Clusters

  Dr. Lars E. Jonsson, Dr. William R. Magro - Intel Americas, Inc.

  The Intel® Itanium® 2 microarchitecture is based on a 64-bit processor architecture that is ideally suited to compute-intensive applications such as LS-DYNA. In fact, Hewlett Packard* has demonstrated outstanding performance of their Itanium 2-based systems on a range of technical computing applications, including LS-DYNA[1]. Given the success of the platform in achieving performance on a per-processor basis, we turned our attention to the speedups achievable with tightly coupled clusters of Itanium architecture-based servers. In this paper, we study the scalability of an Itanium 2-based server cluster consisting of 4-CPU SMP nodes, connected by gigabit Ethernet* and by a high-performance InfiniBand* Architecture interconnect. We study the relative performance of these interconnects, relating the observed application-level performance to the underlying performance characteristics of the interconnect.

• Comparative Study of Material Laws Available in LS-DYNA® to Improve the Modeling of Balsa Wood

  Teddy MAILLOT, Vincent LAPOUJADE, Edith GRIPPON (DynaS+), Bernard TOSON, Nathalie BARDON, Jean-Jacques PESQUE (CEA CESTA)

  In order to compute the requirements for transporting packages in various situations using balsa wood as an energy absorber, a constitutive model is needed that takes into account all of the specific characteristics of the wood, such as its anisotropy, compressibility, softening, densification, and strain rate dependence. Completeness alone is not sufficient for the model, because it must perform appropriately in simulations that include many other non-linear situations, such as being subjected to friction, undergoing large deformations, and even failure. To improve their existing modeling within LS-DYNA, CEA CESTA, in partnership with I2M of Talence, carried out a major experimental campaign both on standard characterization tests and on more complex tests representative of the behavior of real structures. All these tests have been modeled using different LS-DYNA material laws to assess their respective limitations and achieve optimal modeling within the framework of material laws currently available in LS-DYNA. In a final validation phase, this optimized material law has been introduced in a finite element model representative of a real package to evaluate its effect relative to the initial law.

• Comparative Study of Positioning HBM to Cycling Postures Based on Experimental Data

  Maria Oikonomou, Athanasios Lioras, Lambros Rorris, Thomas Nikodelis, Athanasios Mihailidis

  The objective of Crash Analysis is to ensure the safety of a diverse spectrum of road users through the utilization of several finite element (FE) crash simulations. While a considerable number of studies have focused on evaluating the motion and the potential injuries of occupants and pedestrians, the investigation of two-wheel vehicle users remains underrepresented, even though they are considered vulnerable road users and two-wheelers are common personal transportation. Therefore, studying their kinematic behavior in multiple collisions is crucial to ensure safe and convenient travel.

• COMPARING PLATE-LEVEL BLAST ANALYSIS USING ALE, S-ALE AND CONWEP METHODS

  Ahmet Salih Yilmaz, Barkin Sonmez, Ulas Ozcan Erkan

  The simulation analyses of the explosion were performed using three different methods: LBE (Lagrangian-based Eulerian), PBM (Particle-based Method), and ALE (Arbitrary Lagrangian-Eulerian). The reference point cloud data obtained from the scanning process after the explosion tests conducted on a 12 mm thick M400 steel plate indicated a deformation of approximately 12.5 cm at a Y-directional distance between the measured points. Based on this measurement, the explosion analyses were simulated using the aforementioned three methods. The scenario involved the detonation of 6 kg of TNT beneath the structure.

• Comparing the Frontal Impact Responses of the VIVA+ Average Female and SAFER Average Male Human Body Models in a Generic Seat

  E. Svenning (DYNAmore Nordic), K. Mroz (Autoliv), T. Johansen (DYNAmore Nordic), N. Lubbe (Autoliv), J. Iraeus (Chalmers University)

  The VIVA+ 50F average female Human Body Model (HBM), currently in early beta status, was compared to the SAFER average male HBM Version 9 with the aim of investigating differences between females and males in terms of kinematics and injury assessment in frontal impacts. The VIVA+ HBM is under development within the research project VIRTUAL and will be released as open source during the summer 2022.

• Comparison between Experimental and Numerical Results of Electromagnetic Tube Expansion

  J. Shang, S. Hatkevich, L. Wilkerson (American Trim LLC)

  Electromagnetic forming is a complex coupled mechanical-thermal-electromagnetic phenomenon. To accurately simulate this high-velocity and high-strain-rate process, electromagnetism (EM) module of LS-DYNA has been developed. In this paper, the predictive ability of the EM module is assessed through a comparison between experimental and numerical results of electromagnetic tube expansion. The experiment was to apply electromagnetic forming for expansion of Al 6061-T6 tube. Photon Doppler Velocimetry (PDV) was used to measure the velocity during the tube expansion. This process was also modeled using LS-DYNA EM module. Different parameters of Johnson-Cook strength model for Al 6061-T6 were applied to verify the constitutive model parameters for Al 6061-T6. Moreover, 2D axi-symmetric simulations with different mesh densities were performed in this case. A comparison of the expansion velocity between experimental and numerical results is presented and discussed. The good agreement was found between the experimental and numerical results.

• Comparison Between Experimental and Numerical Results of Electromagnetic Forming Processes

  José Imbert, Michael Worswick - University of Waterloo, Canada, Pierre L’eplattenie - LSTC, Livermore, USA

  Electromagnetic Forming (EMF) is a high speed metal forming process that is being studied with interest in both academia and industry as a way of improving existing sheet metal forming. The main thrust of the published research has been increasing the formability of aluminum alloys. Observing and measuring EMF process is made very difficult by the high speeds involved and the tooling used to obtain the final shapes. As with many other processes, numerical simulations can potentially be used to study the details of EMF; however, one limiting factor is the difficulty in modeling the process, since accurate models of both the structural and electromagnetic phenomena must be solved. Researchers have relied on simplifications that use analytical magnetic force distributions, on separate electromagnetic (EM) and structural codes or on in-house codes that can solve both problems simultaneously. In this paper, the predictive ability of the EM module of LS-DYNA® is assessed through a comparison between experimental and numerical results for samples formed by EMF. V-Channel and conical shaped samples were formed using two different EMF apparatuses. For the V-Channel samples a double rectangular coil was used and for the conical samples a spiral coil was used. Both processes were modeled using LS-DYNA®’s EM module. A comparison of the final experimental and numerical final shape and current profiles is presented. It was found that the models provide good qualitative results and are able to predict the major features of the samples studied. Good quantitative agreement between the predicted and measured current profiles was found. The discrepancies observed are the result of numerical issues and the simplifications used in the creation of the specific models. It was found that the software can accurately predict the trends of the forming processes studied.

• Comparison of ALE and SPH Simulations of Vertical Drop Tests of a Composite Fuselage Section into Water

  Karen E. Jackson, Yvonne T. Fuchs - NASA Langley Research Center Hampton

  Simulation of multi-terrain impact has been identified as an important research area for improved prediction of rotorcraft crashworthiness within the NASA Subsonic Rotary Wing Aeronautics Program on Rotorcraft Crashworthiness. As part of this effort, two vertical drop tests were conducted of a 5-ft-diameter composite fuselage section into water. For the first test, the fuselage section was impacted in a baseline configuration without energy absorbers. For the second test, the fuselage section was retrofitted with a composite honeycomb energy absorber. Both tests were conducted at a nominal velocity of 25-ft/s. A detailed finite element model was developed to represent each test article and water impact was simulated using both Arbitrary Lagrangian Eulerian (ALE) and Smooth Particle Hydrodynamics (SPH) approaches in LS-DYNA®, a nonlinear, explicit transient dynamic finite element code. Analytical predictions were correlated with experimental data for both test configurations. In addition, studies were performed to evaluate the influence of mesh density on test-analysis correlation.

• Comparison of Analytical and Numerical Results in Modal Analysis of Multispan Continuous Beams with LS-DYNA

  Abhijit Mahapatra, Avik Chatterjee - Central Mechanical Engineering Research Institute, India

  This paper deals with the study of natural frequencies of vibration of continuous beams supported on hinged end supports with and without overhang. The paper illustrates the analytical formulation of the natural frequencies and corresponding modes of a n-span continuous beam by using a general solution for the Euler-Bernoulli differential equation. Using two different approaches, namely the analytical method and the numerical method some typical continuous beams are analyzed and the conformance of the FEM solver LS-DYNA is tested. The objective is to test the correlation between approximated analytical and numerical methods adopted for this particular study. The computed results are given in tabular form.

• Comparison of Crash Models for Ductile Plastics

  B. Croop, M. Lobdell, H. Lobo (DatapointLabs)

  There is interest in quantifying the value of different material models being used in LS-DYNA today for the modeling of plastics. In our study, we characterize two ductile, yet different materials, ABS and polypropylene, for rate-dependent tensile properties, and we use the data to develop material parameters for the material models commonly used for plastics: MAT_024 and its variants, MAT_089 and MAT_181. We then perform a falling dart impact test, which produces a complex multi-axial stress state, and we simulate this experiment using LS-DYNA. For each material model, we are able to compare simulation to actual experiment, thereby obtaining a measure of fidelity of the simulation to reality. In this way, we can assess the benefits of using a particular material model for plastics simulation.

• Comparison of crash tests and simulations for various vehicle restraint systems

  M. Massenzio, S. Ronel - Université de Lyon, C. Goubel - Université de Lyon / Laboratoire INRETS Equipements de la Route (LIER SA), Lyon Saint Exupéry Aéroport, E. Di Pasquale - SIMTECH

  The use of computational mechanics methods is now largely adopted in the field of Road Side Safety. They are certainly interesting in the context a product development. However, the application of these methods in the certification process raises number of issues, addressed, among others, within the EU CEN TC226/WG1/TG1/CM-E, where some of the authors participate. This paper presents some crash test results and their related simulations, and aims to cover a wide panel of devices, different both in the architecture of the devices and in the outcome of the crash test carried out for certification. After a brief presentation of the failure modes observed, we discuss different validation criteria.

• Comparison of crash tests and simulations for various vehicle restraint systems

  M. Massenzio, S. Ronel - Université de Lyon, C. Goubel - Université de Lyon / Laboratoire INRETS Equipements de la Route (LIER SA), Lyon Saint Exupéry Aéroport, E. Di Pasquale - SIMTECH

  The use of computational mechanics methods is now largely adopted in the field of Road Side Safety. They are certainly interesting in the context a product development. However, the application of these methods in the certification process raises number of issues, addressed, among others, within the EU CEN TC226/WG1/TG1/CM-E, where some of the authors participate. This paper presents some crash test results and their related simulations, and aims to cover a wide panel of devices, different both in the architecture of the devices and in the outcome of the crash test carried out for certification. After a brief presentation of the failure modes observed, we discuss different validation criteria.

• Comparison of Different Material Models in LS-DYNA (58, 143) for Modelling Solid Birch Wood

  G. Baumann, Graz, F. Feist (University of Technology), S. Hartmann (DYNAmore), U. Müller (University of Natural Resources and Applied Life Sciences), C. Kurzböck (Virtual Vehicle Research Center)

  Sustainability plays an increasingly important role in the automotive industry. In order to reduce the ecological footprint, the suitability of alternative bio-based materials like wood is investigated within the project WoodC.A.R. In order for wood to be used as an engineering material for structural components or even crash relevant structures, it has to fulfill high mechanical demands. The material behavior has to be predictable and describable in a numerical simulation. Therefore, two material models *Mat_58 (*Mat_Laminated_Composite_Fabric) and *Mat_143 (*Mat_Wood) were compared and validated against quasi-static tension and compression tests in all its six anatomical directions but also against three-point bending tests with the wood fibers oriented parallel to the beam’s axis. So called “clear wood” samples, i.e. specimens without any growing features, were tested covering the different load levels: linear elasticity, strain-hardening, strain-softening and rupture. While *Mat_58 is an orthotropic material model, *Mat_143 is transversally isotropic which means there is no possibility to distinguish between the radial and the tangential direction of the material. Therefore, a trade-off for both directions has to be found. On the other hand, the material law *Mat_143 is able to consider influences like temperature, moisture content or even the quality respectively sorting degree of the wood. Both material models show that some simplifications considering the hardening and softening behavior, especially in compression have to be taken into account in multi-element specimens. While wood shows softening at longitudinal compression, there is a pronounced hardening in perpendicular direction. The strengths and weaknesses of both material models are discussed.

• Comparison of Faceted Vs Ellipsoid Dummies In Frontal Crash Simulations

  Hovenga P.E., Spit H.H., Kant A.R., Happee R. - TNO Automotive Safety Solutions

  An improved Hybrid-III 50th %ile crash test dummy model has been developed in MADYMO. Advanced multibody techniques have been used to obtain fast computation times with the geometry and potential accuracy of CPU intensive finite element models. So-called facet surfaces have been used in combination with flexible bodies and rigid bodies. The MADYMO contact algorithm has been enhanced with options to separately describe the non-linear compliance of two contacting objects such as a dummy and a seat and orthotropic, penetration- dependent friction has been implemented to capture of ‘belt pocketing’ in the dummy flesh. The available set of component and full dummy validations has been extended with load cases representing the latest restraint system designs and test procedures. A systematic validation has been performed using objective rating techniques to compare the enhanced facet model to the standard ellipsoid model. Objective rating showed that the enhanced facet model provides significant benefits in particular for chest deflections.

• Comparison of FEM and SPH for Modeling a Crushable Foam Aircraft Arrestor Bed

  Matthew Barsotti - Protection Engineering Consultants, LLC

  Passenger aircraft can overrun the available runway area during takeoff and landing, creating accidents involving aircraft damage and loss of life. Crushable foam arrestor bed systems are often placed at runway ends to mitigate such overruns. As the aircraft tires roll through the bed, the material compaction dissipates energy, bringing the aircraft to a controlled stop. A detailed two-year analysis was conducted for the TRB Airport Cooperative Research Program to develop improved arresting systems (Barsotti, et al., 2009). A major thrust of the effort was the development of validated numerical models for crushable arrestor bed materials and deformable aircraft tires. Finite element models for the crushable material manifested several problems due to the unusual mode of deformation experienced, which included significant element skewing, heavy compaction (~90%), and high hourglass energies (~19%). Many meshing and hourglass mitigation strategies were attempted, but they produced only marginal improvement. The Smoothed Particle Hydrodynamics (SPH) method was adopted as a replacement, and detailed performance comparisons of the FEM and SPH versions were made. Error convergence studies using mesh refinement were performed for 1-D, 2-D, and 3-D cases, culminating in the comparison of full tire & arrestor models for each formulation.

• Comparison of Hybrid III Rigid Body Dummy Models

  Stephen Kang, Paul Xiao - Ford Motor Company

  Hybrid III Dummy Computer Aided Engineering (CAE) models have long been used for aspects of vehicle design, including vehicle structure and restraint systems to meet regulatory safety rating targets and internal company requirements. The quality and run time of these CAE models in simulating physical dummies directly affects the usefulness of CAE tools in vehicle development. The objective of this study is to compare the responses of the Madymo Rigid Body dummy and the LSTC Rigid-FE dummy in four crash test modes of one vehicle. During the study, in order to have a fair and sound comparison, the authors have requested each of the companies (TASS and LSTC) to examine the performance of their respective dummy models in essentially the same vehicle environment model. The authors would like to acknowledge their efforts and comments. In particular, frontal crash test modes using the passenger belted and unbelted 50th percentile male Hybrid III dummy and the passenger belted and unbelted 5th percentile female Hybrid III dummy were studied. In each test mode, the Madymo Rigid Body dummies and the LSTC Rigid- FE dummies (beta release) were used. The CAE model results were compared with test results in both time history measurements (acceleration, velocity, displacement, forces, moments) and occupant kinematics (using high speed video). This is the result of one case study and the authors do not intend to draw any general conclusions as to which dummy model is better in relation to the other.

• Comparison of Lagrangian, SPH and MM-ALE Approaches for Modeling Large Deformations in Soil

  Cezary Bojanowski - Argonne National Laboratory, Ronald F. Kulak - RFK Engineering Mechanics Consultants

  Ongoing research at the USDOT funded Transportation Research and Analysis Computing Center (TRACC) at Argonne National Laboratory on bridge stability for bridges with piers in scour holes relies greatly on LS- DYNA® capabilities for modeling large deformations in soil and fluid structure interaction. When it comes to soil modeling, material model MAT_005 Soil and Crushable Foam is often used as a first approximation. It is especially useful when little material characterization is performed--which is usually the case for riverbed soil. Although an abundance of reports can be found where MAT_005 was used with the Lagrangian approach, its use in Smoothed Particle Hydrodynamic (SPH) and Multi Material Arbitrary Lagrangian - Eulerian (MM-ALE) approaches is considerably less documented. This paper presents a comparative study of the performance of MAT_005 with Lagrangian, SPH and MM-ALE approaches for predicting large deformation soil response. For the purpose of validation, simulations were performed for the in-situ experiment of a steel loading pad penetrating into silty clay sand. Using LS-OPT® metamodel based sensitivity analysis was conducted to identify the most relevant material and loading parameters. The results show that the three formulations can produce reasonable predictions at large penetrations. Although very suitable for soil penetration problems, MM-ALE requires iterative adjustments of contact parameters to eliminate spurious leakage. The LS-OPT sensitivity analysis on material parameters indicates the yield function parameters have the greatest influence on the results. Further important parameters are the soil density and appropriate modeling of the soil island boundaries. It was also noted that the choice of the type of domain decomposition greatly affects the compute time.

• Comparison of Laser-Scanned Test Results and Stochastic Simulation Results in Scatter Mode Space

  M. Okamura, H. Oda (JSOL), D. Borsotto (Sidact)

  Recent years, CAE plays more important roles in product development than ever. Good CAE models require validation works with various test data. However, the way of comparison needs to be improved in order to meet the market expectations. Usually a set of test data is given to CAE engineers after all specimen are tested, and test machines are cleaned up. In case CAE engineers find out remarkable differences between simulation results and test results are too great due to mistakes in test laboratories, validation process becomes quite difficult in many cases. In this study, quasi static compression of a crash box is used as an example in order to illustrate the proposed process. A preliminary stochastic simulation and a set of tests is conducted, and the deformation of the crash boxes are transformed into the common modal space. This process makes it possible to assess similarity of deformation modes from multiple simulation results and test results at a glance. This analysis can be conducted at test lab, and fundamental difference between test and simulation can be detected every time specimen are tested. In case an issue is detected, CAE engineers and test engineers can start discussion how to improve the test set up and simulation model in the laboratory.

• Comparison of LS-DYNA and NISA in Solving Dynamic Pulse Buckling Problems in Laminated Composite Beams

  Haipeng Han, Farid Taheri - Dalhousie University, Canada

  In this paper the dynamic pulse buckling of laminated composite beams was analyzed using LS-DYNA and another widely used commercial FE code, namely NISA (Ver.12), developed by EMRC (Engineering Mechanics Research Corp). Two types of impact loadings that could induce dynamic pulse buckling of composite beams were analyzed. The first one was a force applied to the structure in a very short duration (i.e., an impulse load). The other one was the impact of a moving mass having a certain initial velocity. This problem brings considerable challenges if one is to simulate the phenomenon accurately. The main objective of this technical exercise was to investigate the influence of certain numerical parameters on the integrity of the out coming results. The objective was also to assess the performance of a “conventional, general purpose” type FEM program versus LS-DYNA, which is considered as a leading FEM code for the analysis of highly nonlinear phenomena. This was an interesting exercise in demonstrating why one should use codes like LS-DYNA, as oppose the general purpose FEA codes when considering such highly non-linear phenomena. Both abovementioned loading types were considered in this study. In the analysis using LS-DYNA, the force function was introduced by applying an impulse force at one end of the FRP beam. The moving object was also modeled in LS-DYNA by means of a rigid wall having a mass and an initial velocity. The impact by moving object could not be accommodated by NISA, so only the pseudo-impulse type loading could be considered in NISA. Parametric studies were also conducted to investigate the effect of the slenderness ratio, the curvature and the stacking sequences of the FRP beams, as well as the examination of the influence of the initial imperfection used to promote structural instability.

• Comparison of LS-DYNA Version 7, 9 and 11 – A View of an Airbag Supplier

  A. Seeger (iSi Automotive Berlin), S. Stahlschmidt (DYNAmore)

  Several LS-DYNA versions are currently available – R7 is still in use in several projects, the currently mostly used version is R9, future projects will be run in R11. This paper will compare these three versions with focus on some airbag issues.

• Comparison of material models for crash simulation - experimental and simulation work

  S. Mönnich, F. Becker - German Institute for Polymers (DKI), B. Fellner - MAGNA STEYR Fahrzeugtechnik

• Comparison of MM-ALE and SPH methods for modelling blast wave reflections of flat and shaped surfaces

  Jovan Trajkovski (University of Ljubljana)

  The Multi-Material Arbitrary-Language-Euler (MM-ALE) and Smooth-Particle-Hydrodynamics (SPH) are widely used methods for numerical examination of structural response under blast loading. On the other hand, the methods are quite demanding for use. They have their own advantages and disadvantages depending on the structural geometry and its relative position with regard to the blast wave source location. This paper presents comparison results of detailed numerical examination using both the MM-ALE and SPH method. A series of simulation tests were performed using flat and shaped armor steel plates in LS-DYNA. The comparison results showed that the SPH method offers better results and efficiency compared to the MM-ALE method. This is especially evident in cases involving curved structural geometry. The results of this paper will be of great value in the decision making process when choosing an appropriate method for blast response analyses of structures.

• Comparison of Particle Methods : SPH and MPS

  Sunao Tokura (Tokura Simulation Research Corporation)

  SPH (Smoothed Particle Hydrodynamics) implemented in LS-DYNA® has been used widely in various industrial fields as a reliable and robust particle method. At present SPH is considered as one of major numerical simulation method for compressible fluid and solid materials. Recently a unique particle method called MPS (Moving Particle Simulation) has been developed and started to use for some industrial application as a CFD (Computational Fluid Dynamics) solver for incompressible flow. As most application for fluid flow in industry are incompressible, MPS may have a potential ability to treat such problems efficiently than SPH. Both methods have common characteristics that particles are used to discretize continuum domain to be solved. However, as the numerical procedures to solve the governing equation are very different, each numerical simulation method has both inherent advantages and disadvantages. This paper demonstrates the comparison of SPH and MPS for some engineering problems and intends to reveal the difference of these two methods. Comparison of numerical simulation techniques should be very useful for further understanding about multiphysics capability of LS-DYNA even for expert LS-DYNA users. Surface tension model, turbulence model, treatment of Newtonian and Non-Newtonian fluid, coupling with structures and other several topics are discussed. In addition an FSI (Fluid Structure Interaction) problem using MPS software and LS-DYNA is demonstrated in the presentation. In this FSI problem a vehicle is washed away by a tsunami and crashes against a rigid wall. Pressure of tsunami on the surface of the vehicle is computed by MPS software and the deformation of the auto body is calculated by LS-DYNA.

• Comparison of Polyurethane and Epoxy Adhesive High Strain Rate Performance Using Cohesive Zone Model

  Devon Downes, Manouchehr Nejad Ensan, Chun Li

  It is known that the ballistic performance of ceramic composite personnel armour is highly dependent on the thickness of ceramic and backing material. Recent studies have begun focusing on the effect of adhesive bonding between the ceramic and the backing plate, because failure of the adhesive layer can cause separation between the ceramic and backing. This debonding between substrates causes the ceramic to underperform by shattering early due to an imperfect transmission of the stress wave to the backing material. Given that the adhesive plays such an important role in armour, it is important to better understand the underlying physics.

• Comparison of Single Point Incremental Forming and Conventional Stamping Simulation

  A. Belmont, R. Cruz, S. Fernandez, E. Quiroz and R. Perez-Santiago, Universidad de las Américas Puebla, Puebla, Mexico

  This paper resumes simulation related aspects of one project aimed to compare two different sheet metal manufacturing technologies: Incremental Sheet Forming (ISF) and Conventional Stamping. Simulation of stamping in different stages of product development is an established practice in the industry, and the obtained results utilized to validate the process engineering before engaging in tooling fabrication. On the other hand, ISF simulations are difficult to implement, mainly due to its long computational time stemming from the incremental and localized deformation strategy, which for a simple part demands a tool path length in the order of hundreds or thousands of meters.

• Comparison of Strategies for Landmine Modeling in LS- DYNA with Sandy Soil Material Model Development

  Matt Barsotti; Eric Sammarco, Ph.D., P.E.; David Stevens, Ph.D., P.E. (Protection Engineering Consultants)

  As part of the United States Marine Corps (USMC) Mitigation of Blast Injuries through Modeling and Simulation project, Protection Engineering Consultants investigated and compared a range of landmine modeling strategies in LS-DYNA. Dividing the constituent materials into solids (soil) and fluids (air and explosive burn products), various numerical formulations were applied to the two groups in different combinations. Single-formulation strategies included a traditional all-ALE approach and a less conventional all-SPH approach. Hybrid formulation strategies included combinations of ALE fluid and explosive materials with FEM, DEM, or SPH soil. The various single- formulation and hybrid-formulation are compared in terms of implementation, required coupling definitions, stability issues, calculation demands, and overall feasibility. The quantitative performance of three front-runner strategies were compared against benchmark test data. Evaluation cases included initial soil bubble formation, scaled-test impulses against flat plates, scaled-test impulses against angled plates, and full-scale impulses against flat plates. The benchmark tests used sandy soils at varying levels of saturation. A generalized sandy soil modeling approach was used to generate parameters for the Pseudo Tensor material model and the Tabulated Compaction equation of state. The average error for predicted impulse was less than 2.5%, which was obtained from the generalized soil model using a priori material parameter settings and without post hoc tuning.

• Comparison of the Brain Response to Blast Exposure Between a Human Head Model and a Blast Headform Model Using Finite Element Methods

  Rahul Makwana (DEP-Autoline Inc), Sumit Sharma (Eicher Trucks and Buses VE Commercial Vehicles Ltd.), Liying Zhang (Wayne State University)

  Impact induced traumatic brain injury (TBI) has been studied by physical testing using various surrogates, including cadavers, animals, and crash test dummies and by computer modeling including Finite Element (FE) models of human, animal and crash test dummy head. The blast induced TBI research and evaluation of a protective device call for a head model which can mimic wave propagation phenomena through different parts of the head. For proper investigation of head responses and resulting brain injuries due to primary blast exposure, the characteristics of a physical test headform including details of brain/skull anatomy and material properties of the head tissues must be critically designed. The current study was undertaken to numerically evaluate the blast performance of an anatomically realistic headform constructed with existing skull/brain simulant materials in comparison with human head model responses in order to propose a future headform which could be used for testing equipment in blast loading conditions. Quantitative biomechanical response parameters such as pressure, strain and strain rates within the brain were systematically monitored and compared between the blast anatomical headform and the FE human head model. The results revealed that the blast anatomical headform resulted in an average of about 20% over prediction of the biomechanical response parameters in the brain. The results imply that the plyometric based thermoplastic, polycarbonate, polymethylmethacrylate, and polyoxymethylene can be the suitable surrogate skull materials for simulating head responses under blast exposure.

• Comparison of the RHT Concrete Material Model in LS-DYNA and ANSYS AUTODYN

  C. Heckötter, J. Sievers (GRS)

  The goal of this paper is to compare the implementations of the RHT concrete model developed by Riedel, Hiermaier and Thoma in the commercial hydrocodes ANSYS AUTODYN and LS-DYNA for different stress conditions. The considered stress conditions include hydrostatic compaction related to the Mie-Grüneisen equation of state in conjunction with a p-α model, uniaxial tension, uniaxial compression and tri-axial compression. Parameters of the failure surface and residual strength surface were fitted to data of several tri-axial compression tests. Major differences are observed regarding the behaviour under uniaxial tension. It is pointed out that the current model implementations do not consider fracture energy. Hence, the simulation results depend inherently on mesh size in cases where tensile properties are relevant. Furthermore, comparative validation studies based on impact tests dealing with punching failure of reinforced concrete slabs subjected to hard missile impact have been performed. The sensitivity of the ballistic limit velocity as well as residual missile velocities on model parameters is discussed. The work of GRS was carried out in the framework of the German reactor safety research program sponsored by the German Federal Ministry of Economic Affairs and Energy (BMWi).

• Comparison of Two Modeling Approaches for Thin-Plate Penetration Simulation

  Norman F. Knight - Veridian-MRJ, USA, Navin Jaunky - Eagle Aeronautics, USA, Robin E. Lawson - FDC/NYMA, USA, Damodar R. Ambur - NASA Langley Research Center, USA

  Modeling and simulation requirements for uncontained engine debris impact on fuselage skins are described and assessed using the tied-nodes-with-failure (TNWF) approach and the element-erosion (EE) approach for penetration simulation. The TNWF approach is based on coincident nodes generated in selected regions of the target plate that are tied together using a constraint relation and the target plate is modeled with shell elements. The EE approach is based on eliminating or removing of an element once some criterion is reached.

• Complexity based design robustness analysis

  Damien BORDET, Kambiz KAYVANTASH - CADLM

  Application to mechatronic component (vehicle hatchback )

• Composite Forming Simulation with Introduction to J-Composites/Form Modeler Version 2.0

  M. Nishi, S. Wang, S. Dougherty (JSOL), X. Zhu (LSTC)

  JSOL Corporation has developed J-Composites®, a set of tools, which works in cooperation with LS-DYNA®, to facilitate the complex manufacturing process and process-chain simulation of fiber reinforced composite materials. The J-Composites series consists of “Form Modeler”, a tool to set up a press forming analysis model, and “Fiber Mapper”, a tool to map a resin flow simulation result on to a structural mesh. Additionally, “Compression Molding”, a tool for compression molding simulation is in development. This paper introduces some new capabilities of J-Composites/Form Modeler version 2.0 and demonstrates composite forming simulations.

• Composites in High Voltage Applications

  C. Weinberger, M. Rollant (4a engineering)

  In the last years the demands of the automotive industry have led to a strong interest in a more detailed virtual description of the material behavior of thermoplastics. More and more complex material models, including damage and failure, have to be characterized, while keeping the importance of gaining material data quickly in mind. Currently material and failure modeling in crash simulations typically deal with simple von Mises visco-plasticity (*MAT_024) and equivalent strain failure criteria, which cannot describe the complex material behavior of plastics. Past developments have focused on the yield behavior under different load situations (tension, shear, compression), which are implemented in more complex material models like *MAT_SAMP-1 for thermoplastics as well as *MAT_215 for fiber reinforced thermoplastics.

• Comprehensive Correlation of Seat Track Assembly – From Forming to Assembly Test

  S. Sinne, H. Klose, V. J. Dura Brisa, P. Partheymüller (Brose Fahrzeugteile)

  The dimensioning of seat structure including its adjusting components is always a challenge between comfort, lightweight and strength. The main interface between seat structure and vehicle is the s eat track assembly . It enables the length adjustment and transfers a significant amount of the crash load. The increased demands to lightweight , reduction of development time and cost efficiency require a continuous improvement of simulation models regarding accuracy in p redictability.

• Comprehensive Digital Twin of a Beverage Can Body Forming Process and Performance Evaluation

  Sebastijan Jurendic, Maximilian Weiser

  Novelis is a world leader in aluminium flat rolled products and a major supplier to the beverage can-making industry. As such, Novelis is deeply involved in supporting the can-making industry to help shaping a more sustainable future together. Reducing the amount of metal used for each beverage can is a major driver for improving sustainability of the beverage can packaging, thus Novelis is actively investigating and developing state of the art modelling tools and approaches to support further optimization of the beverage can.

• Compression Molding Analysis of Long Fiber Reinforced Plastics using Coupled Method of Beam and 3D Adaptive EFG in LS-DYNA

  S. Hayashi (JSOL); H. Chen, W. Hu (LSTC)

  Composite materials like fiber reinforced plastics (FRP) are becoming more widely used in the automotive industry and have been found very effective in reducing vehicle weight. Recently, long carbon fiber reinforced thermoplastics are increasingly being used for lightweight structural parts with high stiffness, strength and energy absorption performance. Compression molding is considered one of the most efficient manufacturing processes to mass produce FRP parts for automotive applications. Compression molding can form long fiber reinforced thermoplastics into complex shapes with relatively low manufacturing cost and short process time. However, currently there are a very limited number of high-accuracy simulation technologies available that can predict long fiber orientation, filling timing and other behavior required for compression molding. In the first part of this paper, a new simulation technology for compression molding of long fiber reinforced plastics implemented in LS-DYNA is introduced. The main features of this new technology are fibers modelled by beam elements and matrix modelled by tetrahedron solid elements with r-adaptive remeshing function based on an Element-Free-Galerkin (EFG) formulation. In the second part of this paper, an investigation of how to define macroscopic viscosity during compression molding of long fiber reinforced thermoplastics is presented. In the final part of this paper, compression molding simulation for stampable sheet made of long fiber reinforced thermoplastics is presented using a complex shaped punch with one cross-rib geometry. The simulation results show good agreement to experiment. In conclusion, this new simulation technology has great potential to simulate compression molding of long fiber reinforced plastics with high accuracy.

• Compression of LS-DYNATM1 Simulation Results using FEMZIP©

  Clemens-August Thole - Fraunhofer Institute for Algorithms and Scientific Computing

  The standard usage of simulation as part of the automotive design process has increased the demand for archiving simulation results. Intensive collaboration during the development process requires the exchange of simulation results. Compression of simulation results reduces the size of archives and the time for data transfers. Like compression of video streams and pictures, the effective compression of simulation results requires specific tools which exploit the specific data structures of LS-DYNA3D simulation results and allow for a reduced precision of the results. FEMZIP is especially designed for the compression of crash simulation results and achieves a reduction by factor of 7 for reasonable precision requirements.

• Computational Approach to Detect Instability and Incipient Motion of Large Riprap Rocks

  Cezary Bojanowski, Steven Lottes, Transportation Research and Analysis Computing Center Nuclear Engineering Division, Argonne National Laboratory

  Bridge scour is the process of removal of sediment from around bridge abutments or piers. In the most severe cases, scour leads to failure of bridges. One of the ways to stop or prevent the scour is to reinforce the riverbed by placing large rocks on the portion of the riverbed vulnerable to scour at bridge foundation structures (method called riprap installation). The sizing of riprap in scour countermeasure design is based mostly on limited field observations and scaled laboratory tests under ideal controlled conditions. The actual size of riprap required for many field applications is too large for testing in the laboratory. As a consequence, there is significant uncertainty in the formulas for sizing riprap.

• Computational Biomechanics: a challenge at the engineering /life sciences interface5th

  John Middleton, Georges Limbert - Cardiff Medicentre

• Computational Fluid Dynamic of NACA0012 with LS-DYNA ® (ALE & ICFD) and Wind Tunnel Tests

  B. Perin, O. Verdrel, P. Bordenave (DGA Aeronautical Systems), E. Grippon, V. Lapoujade (DynaS+), H. Belloc (Université de Toulouse), I. Caldichoury (LSTC)

  DGA Aeronautical Systems, the technical centre of the French ministry of Defense dedicated to aircraft performance testing and evaluation, combines tests and simulations to validate, among others, parachute systems for the Airdrop Department. The latter also developed modeling and simulation capabilities as a support for evaluation. In parallel, under the authority of the French Ministry of Defense, the Department of Aerodynamics, Energetics and Propulsion (DAEP) of Institut Supérieur de l’Aéronautique et de l’Espace (ISAE), a public institution of higher education and research, conducts research and training support for the Institute. As such, it has developed over the last years the research topic "Aerodynamics of Free Flight Devices" focused particularly on paragliding. The DAEP has expertise and resources in the field of wind tunnel tests and flight aerodynamics of paragliders. DynaS+, a LS-DYNA French distributor and associated services, got a research and innovative subvention from French Government, RAPID financing, to improve the parachute simulation with LS-DYNA. All these entities have shared their skills to better understand and to enhance the knowledge of the fluid representation in the Fluid-Structure Interaction (FSI) simulation of parachute models. They have worked to compare different fluid representations from experimental wind tunnel testing to numerical simulations (ALE and ICFD solvers) around a rigid rectangular wing with NACA0012 airfoil. This study is a complementary work from the publication perspective and concerning the simulation of a flexible ram-air. This paper shows the limitations of the ALE solver to get the aerodynamic coefficients for a wing and the hopes raised by the ICFD solver.

• Computational Material Models for TSCP Plastics Comparison of the Deformation Behavior with MAT 24 and MAT SAMP-1 with DIEM

  M. Dobes, J. Navratil (Robert Bosch)

  The subject of this article is comparison of the deformation and stress response for two computational material models suitable for POM material. Both material models use erosion of finite elements, but in the first case *MAT_24 is used together with MAT_ADD_EROSION and with parameters combination and in the second case *MAT_SAMP-1 is used together with DIEM (Damage Initiation and Evolution Model). The new computation material model SAMP-1 was built based on the original experimental data used for *MAT_24 and additional tests (3-point bending test, puncture test, etc.). The strain rate effect is considered based on the experiments in defined range and other strain rate values were calculated based on the analogue with Johnson-Cook constitutive material model. The attention is focused on tensile/pressure definition of computational material model in plasticity. This is very important effect for good prediction of the cracks with using damage material model DIEM. The next characteristic is an accumulation of the damage which leads to rupture and finite elements deletion. This property is depending on the stress triaxiality. The results of deformation and stress response are very different for both approaches and SAMP-1 gives closer results to the experimental reality. The two types of the practical tasks are used for comparison of the stress and deformation behavior of these two computational material models. The first comparison checks deformation and stress response and second case tests difference between damage models. This work directly connects to previous articles for FSM (Fuel Supply Modules) introduced in preceding LS-DYNA conferences. We find some non-physical behavior of the *MAT_SAMP-1 for specific configuration. So, this article is appeal for LS-DYNA users and developers to propose of solving of this non-physical behavior *MAT_SAMP-1 in specific situation, like as contact, compression loading area.

• Computational Micro-Mechanical Model of Composite & Flexible Woven Fabric with Fiber Reorientation

  Ala Tabiei, Ivelin Ivanov - University of Cincinnat

• COMPUTATIONAL MICRO-MECHANICAL MODEL OF FLEXIBLE WOVEN FABRIC FOR FINITE ELEMENT IMPACT SIMULATION

  Ala Tabiei, Ivelin Ivanov - University of Cincinnati

  This work presents a computational material model of flexible woven fabric for finite element impact analysis and simulation. The model is implemented in the nonlinear dynamic explicit finite element code LSDYNA. The material model derivation utilizes the micro-mechanical approach and the homogenization technique usually used in composite material models. The model accounts for reorientation of the yarns and the fabric architecture. The behavior of the flexible fabric material is achieved by discounting the shear moduli of the material in free state, which allows the simulation of the trellis mechanism before packing the yarns. The material model is implemented into the LSDYNA code as a user defined material subroutine. The developed model and its implementation is validated using an experimental ballistic test on Kevlar woven fabric. The presented validation shows good agreement between the simulation utilizing the present material model and the experiment.

• Computational Modeling of Adiabatic Heating in Triaxially Braided Polymer Matrix Composites Subjected to Impact Loading via a Subcell Based Approach

  Christopher Sorini, Aditi Chattopadhyay, Arizona State University, Tempe, AZ, USA;, Robert K. Goldberg, NASA Glenn Research Center, Cleveland, OH, USA

  The high rate deformation of polymer matrix composites is often accompanied by significant local adiabatic heating; in the case of ballistic impact loading, heat is generated locally within the polymer matrix due to the conversion of plastic work to heat, but the rapid nature of the event does not allow sufficient time for heat transfer to occur. In this work, a user-defined material subroutine implemented into LS-DYNA® to facilitate the analysis of triaxially braided polymer matrix composites subjected to impact loading, including the effects of heat generation due to high rate inelastic deformation of the polymer matrix, is discussed. To approximate the triaxially braided architecture in finite element models in a computationally efficient manner, a subcell-based modeling approach is utilized whereby the mesoscale repeating unit cell of the triaxial braid is discretized in-plane into an assemblage of subcells. Each mesoscale subcell is approximated as a unique composite laminate with stacking sequence determined from the braid architecture and unidirectional layer thicknesses and fiber volume fractions determined from optical micrographs. Each laminate is modeled in LS-DYNA as a layered thick shell element, where integration point strain increments are taken as volume averaged strain increments applied to a doubly-periodic repeating unit cell with one fiber and three matrix microscale subcells. The generalized method of cells micromechanics theory is utilized to localize the globally applied strains to the constituent level to determine the local strains and stresses as well as the global response of the doubly-periodic repeating unit cell via homogenization. An existing unified pressure dependent viscoplastic constitutive model that was previously extended by the authors to nonisothermal conditions is utilized to model the rate, temperature, and pressure dependent polymer matrix. In the polymer constitutive model, the inelastic strain rate tensor components have been modified to explicitly depend on temperature; strain rate and temperature dependent shifts in matrix elastic properties are determined by shifting dynamic mechanical analysis data with the integration point effective strain rate. Since the subroutine is micromechanical in nature, constitutive models are only applied at the lowest (micro) length scale. Local temperature rises in the polymer matrix due to inelastic deformation are computed at the microscale via the heat energy equation, assuming adiabatic conditions. Simulations of quasi-static straight-sided coupon tests and flat panel impact tests on a representative [0°/60°/–60°] triaxially braided composite material system are conducted to validate the subcell methodology and study the effects of adiabatic heating on the simulated impact response. Time histories of simulated and experimentally measured out-of-plane displacement profiles during the impact event are compared; good agreement is found between experiments and simulations. Simulation results indicate significant internal temperature rises due to the conversion of plastic work to heat in an impact event.

• Computational Modeling of Geosynthetic Reinforced Soil (GRS) Composites Under Axial Loading

  Marta Sitek, Cezary Bojanowski (Argonne National Laboratory)

  Modeling the behavior of a granular medium, such as soil, as a finite element continuum is a challenging task. A significant number of constitutive models for soils are implemented in commercial software, but their application is limited to specific cases. The main goal of the work presented in this paper was to select a soil model implemented in LS-DYNA ® that performs best in simulating a laboratory compression test of geosynthetic reinforced soil (GRS). The full-scale geosynthetic reinforced soil composite tests were performed at FHWA’s Turner-Fairbank Highway Research Center. An example of a free-standing mini-pier test in a three-dimensional stress-strain state is considered. The specimens vary with geosynthetic reinforcement strength and spacing. The models are built in stages, as soil is placed layer by layer, with geotextile inserts, and compacted. The specimens are then axially loaded until collapse. The history of vertical displacements of the top surface, horizontal displacements on the free surfaces and the ultimate load are recorded and compared with the experimental results. A preliminary study was performed to find the most appropriate soil material model available in LS-DYNA, which would represent well the behavior of granular soil in interaction with a geotextile. Computational results closest to experimental ones were obtained with the use of the *MAT_HYSTERETIC_SOIL (079) model in combination with the *MAT_FABRIC (034) material model to represent the behavior of the geotextile. Additionally, the model *MAT_ADD_EROSION was used to simulate the failure of the geosynthetic material under loading. The simulations show a good correspondence with the experiments. Failure modes of the computational models are similar to the ones obtained in the laboratory. Even though local damage of the soil was not captured, the axial strain and the failure load are represented well.

• Computational modeling of tensile split-Hopkinson bar tests on carbon-carbon composites using continuum and mesoscale approaches

  Christopher Sorini, Roberto Enriquez Vargas, Alexander Carpenter, Drew Hackney, Sidney Chocron

  The high strength, toughness, quasi-ductility over monolithic ceramics, and elevated temperature oxidation resistance make carbon-carbon (C/C) ceramic matrix composites (CMCs) excellent candidates for hypersonic vehicle components, which will experience high temperatures and oftentimes high strain rates in service. However, accurate characterization of the material behavior under such extreme/harsh conditions presents significant challenges.

• Computational Modeling of the TPU Shock Absorber using LS-DYNA

  Ahmet Mete SABAH, Buğra BALABAN

  In this study, various analysis and test activities are presented, which were carried out for the development of shock-mitigating floor mats. These impact-absorbing floor mats are produced from hyperelastic materials and are designed to absorb high-amplitude, short-duration shock loads in defense or civil applications. Throughout the study, the *MAT027 model is examined for its suitability in modeling hyperelastic materials in both static and dynamic analyses, conducted using the non-linear finite element code LS-DYNA®. The *MAT027 model accurately describes the behavior of hyperelastic materials and is often preferred for this type of material. To correctly apply this model, specific parameters pertaining to the hyperelastic material must be determined. This study primarily focuses on the determination of these material parameters through tests conducted on samples made of Thermoplastic Polyurethane (TPU) material. In the initial phase of the study, a literature review concerning TPU material was conducted, and material parameters were obtained using the test data presented in this study. The material parameters were then optimized using LS-Opt® to achieve the best material behavior. Following the determination of material parameters, dynamic simulations were performed using LS-DYNA®, and the simulation results were subsequently compared with experimental data. With the material parameters in hand, the second phase of the study involved the design of cellular structures with various geometric shapes. The force-displacement graphs of these newly designed shapes were analyzed through dynamic analyses.

• Computational simulations of aluminum foam projectile behavior

  M. Borovinsek, M. Vesenjak, Z. Ren - University of Maribor, S. Itoh - Kumamoto University

  The results of experimental tests and computer simulations of open-cell aluminum foam behavior under high deformation rates are presented. Experimental Taylor impact tests showed, that the open-cell foam projectile deforms already during its acceleration in the Taylor barrel. This behavior was investigated further by use of computer simulations with the LS-DYNA. The simulations confirmed very high sensitivity of open-cell foam projectile to the acceleration.

• Computer Generation of Sphere Packing for Discrete Element Analysis in LS-DYNA

  Z. Han, H. Teng, J. Wang (LSTC)

  The constructive algorithms for sphere packing are based on the pure geometrical computation. They are very efficient and robust for building very large sphere packings with millions of spheres in a few minutes. A constructive algorithm has been developed in LS-DYNA for arbitrary 3D geometries with the size distribution control. The brief introduction of the algorithm is presented in this paper. The procedures and some generated sphere packings are also presented to demonstrate its application for the discrete element analysis by using LS- DYNA.

• Computer Simulated and Experimental Verification of Tooling for Progressive Deep Drawing.

  Peter Kostka, Peter Cekan - Slovak University of Technology in Bratislava

  The ability to predict different process conditions in deep drawing is essential for die face designers, tooling, stamping and manufacturing engineers. These predictions in turn affect the speed, accuracy and cost of the final produced product. This paper briefly discusses the possibilities of controlling the blankholder pressure distribution and shows some computer simulations done in DYNAFORM, with the results being experimentally verified with tooling designed by the authors.

• Computer Simulation of Sheet Metal Forming and Drawbead Effects Using eta/DYNAFORM

  Yinghong Peng, Zhaoyuan Wang, Xiongfei Yin, Xueyu Ruan - Shanghai Research Institute of Tool & Die

  The kernel technology of a computer simulation system and the general procedure of dynamic simulation in sheet metal forming are presented. As an example, processing parameters of the experimental die of a car inner door panel were optimized with eta/DYNAFORM software. The appropriate round corner of punch, BHF and the correct layout of the drawbead were obtained.

• Computing on GPUs

  Prof. Dr. Uli Göhner - DYNAmore GmbH

  The increasing power of GPUs has led to the intent to transfer computing load from CPUs to GPUs. A first example has been the porting of computing intensive algorithms like e.g. ray-tracing algorithms from CPU to GPU. Through the Compute Unified Device Architecture (CUDA [4]) GPUs can also be used to increase computing speed for High Performance Computing applications. In this paper different parallelization strategies for different processor architectures are presented. They are compared and first experiences using GPUs for a collection of numerical applications are given.

• Computing on GPUs

  Prof. Dr. Uli Göhner - DYNAmore GmbH

  The increasing power of GPUs has led to the intent to transfer computing load from CPUs to GPUs. A first example has been the porting of computing intensive algorithms like e.g. ray-tracing algorithms from CPU to GPU. Through the Compute Unified Device Architecture (CUDA [4]) GPUs can also be used to increase computing speed for High Performance Computing applications. In this paper different parallelization strategies for different processor architectures are presented. They are compared and first experiences using GPUs for a collection of numerical applications are given.

• Concept Design of an A-Pillar Mounted Airbag for Pedestrian Head Protection

  Jianfeng Yao, Jikuang Yang - Chalmers University of Technology

  Accident investigations have shown that in pedestrian-versus-vehicle accidents, windshield edges, A-pillars, cowls are the main sources for severe head injuries due to their high stiffness. To mitigate head injury severities, it is necessary to improve the safety performance of these structures. An A-pillar mounted airbag system (AMAS) was devised with the aim to prevent head from directly impacting against stiff structures such as A-pillars, windshield frames and edges. The airbags of the AMAS are installed inside A-Pillars. When a car strikes with a pedestrian, the airbag will break the A-Pillar cover and deploy along the whole APillar to cover the stiff structures. In this study, the safety performance that can be provided by this system was evaluated by mathematical simulations. A finite element (FE) Ford Taurus car model and an EEVC headform model were used to simulate the pedestrian headform tests as proposed by EEVC. FE airbag models were developed and the influence of airbag parameters, including airbag type, inflow mass rate, vent size and deploy timing, were investigated by mathematical simulations. The safety performance of the AMAS was also evaluated by an FE human head model. The results show that this system can greatly reduce the head injury severity in case a pedestrian head impacts with A-pillar areas.

• Concepts toTake Elastic Tool Deformations in Sheet Metal Forming into Account

  A. Haufe, D. Lorenz - DYNAmore GmbH, Germany, K. Roll, P. Bogon - Daimler AG, Germany

  In recent years the development of more and more niche products, i.e. cars with different external appearance, has become a remarkable trend in the automotive industry. This trend, however, generates higher costs for individual tooling geometries that are traditionally made as stiff as possible. A second trend is the increasing use of high and ultrahigh strength steel grades for bodies in white. Here too the design philosophy for the tools in sheet metal forming is based on a rather rigid and stiff tool approach. It is clear though, that a tremendous amount of money could be saved by designing the tools such, that their elastic deformation during the forming process is taken into account. This would lead to lighter and hence more inexpensive tools. The traditional approach to design the tool geometry by finite element simulations with rigid tools. Clearly, if elastic deformations are to be accounted for in such models, the assumption of a rigid tooling geometry needs to be abandoned. Here the straight forward approach would be to discretize the tool by a sufficiently accurate full 3D finite element model. Additionally the machine stiffness may be added to the model for completeness. Obviously this will lead to prohibitively increased computing time especially for large parts. A simple yet effective way to take the elastic deformations nonetheless into account is to condensate the discretized machine and tool geometry once and reuse it in subsequent simulations runs. The paper will discuss recent features in LS-DYNA® that allow the static condensation of elastic tool and machine geometries. Furthermore the application of the “deformable rigid bodies”- approach is shortly discussed.

• Conjugate Heat Transfer in LS-DYNA®: An Update of the ICFD-Structure Coupling Capabilities for Hot Stamping

  Iñaki Çaldichoury Rodrigo Paz, Facundo Del Pin, Chienjung Huang (Livermore Software Technology, an Ansys company)

  Hot stamping is an essential process in the long and complex assembly chain that will lead to the manufacturing of a complete vehicle. The three main steps consist in a metal sheet being heated, formed and rapidly cooled, yielding parts with high strength and light weight. The main focus of research in that area resides in reducing cycle times, i.e. the time it takes for the tools to cool down, while simultaneously maintaining a high integrity of the formed workpieces. To that effect, the design of cooling systems has drastically increased in complexity and new guiding models are needed for the engineer to be able to identify and then correct potential ‘dead flow zones’, ‘hot spots’ and other problematic areas. Simulation is increasingly viewed as the most general and versatile tool to tackle those challenges. The physics require a coupled thermal, fluid and often mechanical simulation for which a Multiphysics code is needed. Within LS-DYNA, the ICFD solver offers such capabilities and efforts have been continuous over the years to improve existing capabilities and add new ones in conjunction with user feedback [1] [2]. This paper will offer an overview of the existing capabilities, reveal some best practice approaches as well as introduce the latest developments, with a special focus on the fluid-structure interface and how turbulent effects may affect the heat transfer.

• Consideration of Manufacturing Effects to Improve Crash Simulation Accuracy

  Curd-Sigmund Böttcher, Steffen Frik - Adam Opel AG

  The confidence level of crash simulations is mainly determined by a well-defined finite element representation of the vehicle structure, correct modelling of the kinematics, and the material properties being applied. In the past, materials were described by quasistatic – or, if available – dynamic stress-strain characteristics. Besides this, each sheet metal part was assumed to have a uniform gage and material characteristics. However, it is a well-known effect that the physical properties of steel can alter significantly during the manufacturing process. This comprises an increase of material stiffness due to plastic deformation as well as gage changes. The amount of these changes is of very local nature and cannot be covered by simply scaling material properties and gages. In the past, crash software tools didn’t support the introduction of these local effects, so that they couldn’t be taken into account. In the meanwhile LS-DYNA has the capability to import information provided by stamping tools such as PAMSTAMP or AutoForm. Thereby a very important part of the material properties can be introduced into the crash simulation models, leading to a significantly increased correlation to test results. The impact of this effect on crash performance was analysed for a recent vehicle project and will be discussed in detail.

• Consideration of Orientation Properties of Short Fiber Reinforced Polymers within Early Design Steps

  G. Gruber, A. Haimerl, S. Wartzack (Chair of Engineering Design KTmfk. University of Erlangen-Nuremberg FAU)

  Abstract Within the modern automotive industry there is an increasing application of parts made of short fiber reinforced polymers (SFRP). The reasons are their beneficial mechanical properties and their series production capability. However, the prediction of their crash behavior by simulation is very complicated, since a precise simulation requires considering the fiber orientation distribution. That’s why, in early design steps often only imprecise, isotropic simulation approaches are deployed in order to save calculation time and license costs for additional software tools. The aim of the present paper is to introduce a simplified simulation approach allowing an anisotropic simulation taking into account the orientation data obtained by an injection molding simulation. To ena ble its application in ®early design steps only standard functions already implemented in LS-DYNA are deployed. The complex material behavior of short fiber reinforced polymers is represented by overlapping two standard material models of LS-DYNA in one single shell definition. The input parameters of the resulting phenomenological material description are obtained by using optimization methods. The methodology being used to convert the orientation data in order to set up an executable input deck is supported by two self-developed software tools. The first software tool extracts the orientation angles from the process simulation by assigning fiber orientation tensors to corresponding shell elements of the mesh of the crash simulation. For each shell element the orientation data are averaged and projected on the shell. By doing so, the complex orientation state is reduced to just three values per shell element – one fiber orientation angle and two fiber orientation probability values. Based on these data, the second software tool creates the executable input deck. The legitimacy of the presented approach is proved by an experimental validation: SFRP-plates are analyzed within a drop weight test. Despite the mentioned simplification (reduction of the complexity of the orientation state) the numerical results show a strong correlation with the experimental data.

• Considerations for LS-DYNA Efficiency in SGI IRIX and Linux Environments with a NUMA System Architecture

  Stan Posey, Nick Meng - SGI

  Manufacturing industry and research organizations continue to increase their investments in structural analysis and impact simulations such that the growing number of LS-DYNA users continue to demand more from computer system environments. These demands typically include rapid single job turnaround and multi-job throughput capability in a multi-user high-performance computing (HPC) environment. What is more, many LS-DYNA simulation environments coexist with other mechanical computer aided engineering (MCAE) software for structural analysis and computational fluid dynamics that all compete for system resources such as CPU cycles, system bandwidth, memory, disk storage and I/O. This paper examines the computational efficiency of structural analyses and simulations for relevant applications in LS-DYNA. Parameters such as model size, element types, and simulation conditions can produce a wide range of computational behavior such that consideration should be given to how system resources are allocated and configured. The computational characteristics of the SGI® Origin® 3000 servers, based on IRIX® and MIPS®, and the SGI® Altix™ 3000 servers, based on Linux® and Itanium® 2 from Intel®, are examined for both turnaround and throughput requirements that include industrial-size examples. In addition, simple guidelines on proper system configuration and innovative use of available SGI system resource management tools are provided that are designed to maximize LS-DYNA productivity. Introduction Mechanical design and manufacturing organizations increasingly rely on highperformance computing (HPC) technology and mechanical computer-aided engineering (MCAE) applications to drive innovation in product development.

• Considerations for LS-DYNA Workflow Efficiencies in an HPC Linux Environment

  Stanley Posey - HPC Applications Development

  Manufacturing industry and research organizations continue to increase their investments in structural analysis and impact simulations such that the growing number of LS-DYNA users continues to demand more from computer system environments. These LS-DYNA workflow demands typically include rapid single job turnaround and multi- job throughput capability for users with diverse application requirements in a high-performance computing (HPC) environment. Additional complexity arises from the need for many LS-DYNA HPC environments to coexist with other computer aided engineering (CAE) software for a variety of multi-physics and multi-scale structural and computational fluid dynamics analyses that all compete for the same HPC workflow resources. For today’s economics of HPC, these resources such as CPU cycles, memory, system bandwidth and scalability, storage and I/O, and file and data management – must deliver the highest levels of CAE productivity and HPC reliability that is possible from a Linux platform environment. This presentation examines workflow efficiencies of CAE simulations for relevant applications in LS-DYNA for an HPC Linux platform developed by SGI. LS-DYNA modeling parameters such as model size, element types, schemes of implicit and explicit (and coupled), and a variety of simulation conditions can produce a wide range of computational behavior and data management requirements, such that careful consideration should be given to how system resources are configured, deployed, and allocated to meet increasing user demands. The HPC system technology of the SGI® AltixTM clusters and servers, based on Linux® and Itanium® 2 from Intel®, have demonstrated both LS-DYNA turnaround and throughput achievement that includes industrial-sized examples. In addition, SGI simulation data management technology of HPC file systems and data storage tools, are providing the LS-DYNA workflow management necessary to maximize user productivity, and enable a user roadmap of increasing LS-DYNA modeling fidelity.

• Considering damage history in crashworthiness simulations

  Frieder Neukamm, Markus Feucht - Daimler AG, André Haufe - DYNAmore GmbH

  Crashworthiness simulations using explicit Finite Element methods are a central part of the CAE process chain of car body development. Since crash tests of prototype cars at an early development stage are very expensive, a maximum in predictive performance of crash simulations can make a substantial contribution to a cost-efficient car development process. A central issue to ensure this, is an accurate prediction of crack formation in crashworthiness simulations. As the use of advanced high-strength materials in modern car body structures is increasing, crack formation is more likely to occur in such parts of the body-in-white. Typically, structural parts of a car body are manufactured by means of deep-drawing processes. Due to this, the local properties of these parts can be changed remarkably compared to the unprocessed material. In order to be able to accurately predict crack formation, the damage history including local plastic strain and pre-damage has to be considered. Since the use of forming simulations has become usual practice for sheet metal manufacturing, a damage model suitable to be used for both forming and crashworthiness simulations will be presented in the following. Based on the well-known failure criterion of Johnson and Cook, a generalized formulation is proposed that can account for complex failure modes in modern high strength materials. Numerical examples will be presented to demonstrate the practical use of the damage model for the process chain of sheet metal manufacturing.

• Considering damage history in crashworthiness simulations

  Frieder Neukamm, Markus Feucht - Daimler AG, André Haufe - DYNAmore GmbH

  Crashworthiness simulations using explicit Finite Element methods are a central part of the CAE process chain of car body development. Since crash tests of prototype cars at an early development stage are very expensive, a maximum in predictive performance of crash simulations can make a substantial contribution to a cost-efficient car development process. A central issue to ensure this, is an accurate prediction of crack formation in crashworthiness simulations. As the use of advanced high-strength materials in modern car body structures is increasing, crack formation is more likely to occur in such parts of the body-in-white. Typically, structural parts of a car body are manufactured by means of deep-drawing processes. Due to this, the local properties of these parts can be changed remarkably compared to the unprocessed material. In order to be able to accurately predict crack formation, the damage history including local plastic strain and pre-damage has to be considered. Since the use of forming simulations has become usual practice for sheet metal manufacturing, a damage model suitable to be used for both forming and crashworthiness simulations will be presented in the following. Based on the well-known failure criterion of Johnson and Cook, a generalized formulation is proposed that can account for complex failure modes in modern high strength materials. Numerical examples will be presented to demonstrate the practical use of the damage model for the process chain of sheet metal manufacturing.

• Considering Manufacturing Induced Inhomogeneity in Structural Material Models (VMAP)

  B. Jilka, P. Reithofer (4a engineering)

  The ITEA VMAP project aims to gain a common understanding of and interoperable definitions for virtual material modelling in Computer Aided Engineering (CAE). Using industrial use cases from major material domains and representative manufacturing processes, new concepts will be created for a universal material exchange interface for use in virtual engineering workflows. [1] In the VMAP consortium with nearly 30 partners, 4a is focusing on injection molding of plastics. Two sub use cases – namely impact behavior of fiber reinforced thermoplastics and structural behavior of foamed parts - are presented in this contribution.

• Considering the Local Anisotropy of Short Fibre Reinforced Plastics: Validation on Specimen and Component

  Finding the optimal design of plastic components using FEM tools has become an increasingly important topic for companies and research institutions. However, typical simulation models neglect the local anisotropy of injection moulded plastic components and often fail to predict the correct mechanical behaviour and failure mode. Using an integrative simulation approach, the manufacturing process and the resulting local anisotropies can be incorporated in a structural finite-element model which significantly enhances the predictive quality of the model. This is especially the case for glass-fibre reinforced polymers, where the difference between the mechanical behaviour longitudinal and lateral to the fibre is high. This also concerns the strength of weld lines, which are often inevitable in injectionmoulded parts. Fibre orientation needs to be considered because it is indispensable for understanding weaknesses of a polymer part design. Injection-moulding simulation is already a common tool for process simulation and allows calculating the fibre orientation. For structural analyses, various anisotropic material models have been developed or improved in the last years and interfaces to transfer the orientation become more and more available. This now allows making the step to integrative simulation also on an industrial level. The anisotropic material model, used in this study is *MAT_4a_MICROMEC, a micromechanics model based on the Mori-Tanaka Meanfield Homogenization [1]. In this study, the experience of implementing an integrative simulation approach is presented. Furthermore, the fibre orientation determined by mouldflow simulation and the prediction of mechanical behaviour on specimen and component level are validated.

• Constitutive Model of Filled Elastomers Capable of Capturing Mullins Effect, Hysteresis, Induced Anisotropy and Permanent Set – Part I: Model Theory & Implementation

  R. Chandrasekaran, M. Hillgärtner, M. Itskov (RWTH Aachen University), M. Müller, F. Burbulla (Dr. Ing. h.c. F. Porsche)

  In this contribution, a finite element implementation of a micromechanically based constitutive model describing several inelastic effects of filled rubbers in multiaxial deformation states is presented. The model describes the elastic and inelastic effects of filled rubbers and is based on the network decomposition concept. Accordingly, the rubber network is decomposed into an isotropic elastic network E, responsible for the polymer matrix, and two anisotropic permanent damage networks (M and H) which are responsible for the filler-polymer interaction. The anisotropic damage networks M and H are capable of capturing the Mullins effect, hysteresis, permanent set and induced anisotropic stress softening. This model is implemented into LS-DYNA® by means of a subroutine within *MAT_USER_DEFINED _MATERIAL_MODELS (UMAT). The user can easily switch between different combinations of elastic and inelastic models by activating and deactivating each network. The user can also select the number of directions to be considered depending on the complexity of the loading history. The model with appropriate material constants demonstrates good agreement with experimental data.

• Constitutive Model of Filled Elastomers Capable of Capturing Mullins Effect, Hysteresis, Induced Anisotropy and Permanent Set – Part II: Experiments & Validation

  M. Hillgärtner, R. Chandrasekaran, Mikhail Itskov (RWTH Aachen University), M. Müller, F. Burbulla (Dr. Ing. h.c. F. Porsche)

  This contribution discusses experiments necessary to describe the behavior of filled elastomers under large strains. Filled elastomers show a variety of inelastic phenomena such as Mullins effect, hysteresis, induced anisotropy, and permanent set. While uniaxial tension tests to rupture provide virgin loading curves, other tests are necessary to gather information about the inelastic effects mentioned above. In order to capture these phenomena experimentally, cyclic uniaxial tension tests with stepwise increasing load amplitudes are carried out. Since experimental stress-strain curves characterize some restricted set of defined loading conditions (such as uniaxial test, pure shear, or equi-biaxial tension), additional investigations of two-dimensional strain data from arbitrary deformations states are necessary. This strain data can be obtained for example by digital image correlation. In particular, we demonstrate how the previously described constitutive model can be calibrated using a variety of experiments. We verify the calibration comparing the results of our subroutine implemented as UMAT in LS-DYNA with two-dimensional strain data obtained from digital image correlation of a plate with a hole subjected to tension. The described model shows good agreement with the obtained data.

• Constitutive Modeling for Composite Forming Simulation and Development of a Tool for Composite Material Design

  Masato Nishi, Tei Hirashima, Sean Wang (JSOL Corporation)

  Many of the existing FE models in macroscopic forming simulation of fiber fabric have neglected out-of-plane bending stiffness, by using membrane elements, as it is very low compared to in- plane stiffness. To consider this, the shell-membrane hybrid model (S-M model) proposed in the author’s previous study can capture bending stiffness as a function of the rotation of the mid- surface. However, influence of the transverse shear deformation upon the bending behavior is not able to be described in this model. In this study, in order to simulate the transverse shear deformation robustly, the thick-shell model (TS model) based on Reissner-Mindlin plate theory is applied in forming simulation of carbon fiber fabric. To compare the predictive capability of out- of-plane deformation, especially wrinkling, by the TS model to the conventional S-M model, we identify the material parameters of each model through a series of coupon experiments. In the S- M model, the bending property is derived from 3-point bending tests across yarn and in a 45 ̊ direction, regardless of in-plane properties. On the other hand, the transverse shear modulus is derived from 3-point bending tests with the in-plane properties because the bending behavior results from the rotation of the mid-surface and the transverse shear deformation in the TS model. To complete the study, the forming simulations are carried out by these two FE models and verified by means of comparison with the actual experimental deformations. Small wrinkles that are not captured in the S-M model can be captured in the TS model. Furthermore, a software tool for composite forming simulation that JSOL is developing is presented.

• Constitutive Modeling of Biological Soft Tissues

  Attila P. Nagy, David J. Benson, Livermore Software Technology Corporation, Livermore, CA 94551, USA;, Vikas Kaul, Mark Palmer, Medtronic plc, Minneapolis, MN 55432, USA

  In the present communication, we introduce a class of material models primarily aimed at simulating the elastic and viscous behavior of biological soft tissues in LS-DYNA®. The constitutive law is modular and each module may comprise of different models. Consequently, the analyst may easily change models in a module and also include additional modules to account for more complex material behaviors within the same keyword. In its most general form, the material is considered nearly incompressible, anisotropic, and hyperelastic with the passive behavior defined using a decoupled strain energy function. The contractile and viscoelastic behavior of the tissue may be considered by invoking extra modules. The models are verified using a wide range of recently published results and show excellent agreement.

• Constrained Multidisciplinary Topology Optimization

  Willem Roux, Imtiaz Gandikota, Guilian Yi (Livermore Software Technology – an ANSYS Corporation)

  For multidisciplinary topology optimization it can be difficult to select the weights for each load case. This becomes even harder if there are multiple design considerations per case. But if constraint values can be defined, then the problem is solvable, because the problem is transformed into one of satisfying the constraints. The most difficult constraint to control is that of the crash pulse, because the existing linear methodologies cannot be used – solutions such as multipoint strategies and spatial kernels must be introduced instead. The NVH constraints are however linear and solving the NVH constraints in combination with the crash pulse becomes a two-level problem. In this paper we show multidisciplinary design optimization considering constraints from impact, linear statics, and frequency load cases.

• Contact and Sliding Simulation of Rubber Disk on Rigid Surface with Microscopic Roughness

  Sunao Tokura - JRI Solutions, Ltd.

  It is crucial to obtain detailed information about frictional interaction between tire and road surface to estimate performance of vehicle brake system or tire on real road surface. Simulation using Finite Element Method (FEM) in addition to experimental procedure is regarded to be useful to investigate contact behavior between tire and road surface. However, indeed, it is difficult to apply FEM simulation for such a problem since contact and sliding of rubber on rough rigid road surface may cause local large element distortion on rubber material and simulation may fail by negative volume error. In this paper, modeling of a rubber disk and rigid road surface with microscopic roughness, which can be used as a baseline for simulation of contact behavior between tire and road surface, is described. Some investigation for analysis technique to ensure stable computation of rubber disk and road surface model under severe condition has been made. It was shown that proposed modeling technique could avoid extreme mesh distortion during simulation. It is expected that the proposed technique can be used in simulation of rolling/sliding tire on real road surface.

• Continuous Simulations from Resistance Spot Welding Process to Joint Strength

  S. Yagishita, T. Kawashima, N. Ma (JSOL)

• Continuous Surface Cap Model for Geomaterial Modeling: A New LS-DYNA Material Type

  Leonard E Schwer - Schwer Engineering & Consulting Services, Yvonne D Murray - APTEK, Inc.

  The Continuous Surface Cap Model is a new addition to the LS-DYNA geomaterial modeling library of constitutive models (Material Type 145). This new model should replace the use of the Geological Cap Model (Material Type 25) for most applications. The Continuous Surface Cap Model maintains all the functionality of the Geological Cap Model with the addition of the third stress invariant, strain rate effects, and damage modeling. The Continuous Surface Cap Model has also been reported to be about three times faster than the Geological Cap Model in a large scale application. This article briefly describes some of the model features and illustrates its application.

• Continuum-based Particle Gas (CPG): A New Approach for Airbag Deployment Simulations

  Edouard Yreux, Jason Wang, Inaki Caldichoury, Mohammed Mujtaba Atif

  The evolution of automotive safety systems has witnessed a remarkable journey over the past few decades, with airbags emerging as pivotal components in mitigating the severity of injuries during vehicle collisions. Initially conceived as relatively simple passive restraint systems, airbags have undergone a profound complexification in their design and functionality, driven by the relentless pursuit of enhanced occupant protection and regulatory compliance. Today, modern vehicles incorporate a diverse array of airbags strategically positioned throughout the cabin to address various collision scenarios. From front and side airbags to curtain and knee airbags, this proliferation underscores the nuanced approach to occupant protection adopted by automotive manufacturers.

• Control System in LS-DYNA

  C. Keisser (DYNAmore); I. Yeh (LSTC)

  Control System is a very old concept aimed at improving or changing the behavior of any dynamic system. In our daily lives, there are many control applications like in a toaster or in room temperature regulators but also in our cars when using cruise control or ABS. More recently, Control System appears to be also very useful and powerful in pre-crash safety or in modeling Human Body response. The control can be as simple as an On/Off action (open-loop control). Or, for closed-loop control, output measurements provided by sensors feed the controller which then uses actuators to modify the system behavior. Several software like MATLAB/Simulink, Scilab, or Octave have their own control system toolbox. In LS-DYNA, several control features are currently being developed: an interface to connect with MATLAB or Scilab, an internal Control System Toolbox integrating control tools like the popular PID controller, and the piezo-electric material.

• Corpuscular method for airbag deployment simulations

  Lars Olovsson, IMPETUSAfea AB

• CORrelation and Analysis (CORA) in Visual-Environment

  Megha Seshadri (ESI Group), Rohit Ramanna (ESI North America), Shivakumar Shetty (Humanetics)

  CORA (Correlation and Analysis) rating is a curve comparison technique, to evaluate the time-history signals. CORA requires at least two curves for comparison, the reference curve (test result) and the comparison curve (simulation). This method is mainly used in Injury Studies.

• Correlation of the Federal Motor Vehicle Safety Standard 225 (FMVSS225) Requirement of an Automotive Seat System Using LS-DYNA

  Frank Xu, Partha Chowdhury, Babushankar Sambamoorthy, Tuhin Halder - Lear Corporation

  The National Highway Traffic Safety Administration (NHTSA) has issued a final rule for a new safety standard related to child seats and their anchorage systems in vehicles. FMVSS 225 – Child Restraint Anchorage Systems (CRAS) requires that motor vehicle manufacturers provide a new method for installing child restraints that are standardized and independent of the vehicle seat belt. The requirements for CRAS can ensure their proper location and strength for the effective securing of child-occupants in an automotive seat system. There are four pull tests for FMVSS 225 - forward pull with top tether, forward pull without top tether, lateral pull to the right, and lateral pull to the left. The tests are performed by applying a specified load to the child seat anchorage system using Static Force Application Devices (SFAD), mandated by NHTSA. The regulation requires that the displacement of the load application point on the SFAD, along the horizontal plane, should be less than 125 mm and there should not be any structural separation [1][2]. LSDYNA is widely used for the “quasi-static” simulation of the automotive seat systems and plays a key role in improving design and saving cost. Due to the dynamic effects in quasi-static simulations, correlating the displacement for FMVSS 225 using LSDYNA becomes a challenge. At Lear Corporation’s test lab, physical tests were conducted on number of different seats and the results were correlated by simulating the tests in LSDYNA. Based on the knowledge and data collected over a period of 3 years, the authors have established a methodology to simulate FMVSS 225 and correlate accurately with the physical test.

• Correlative Approach to Mine Blast Effects via Conducting Real Test Campaigns and Simulating in LS-DYNA

  İzzet ÖZCAN, Buğra ISIKER

  In this study, pressure data were collected by conducting free field blast tests with explosives placed inside the steel pot to verify the explosive model. Free field blast analysis was performed using the Structured Arbitrarily Lagrangian -Eulerian (SALE) method in the LS-DYNA® software under the same boundary conditions, and the pressure values obtained from the test were compared. Plate tests were performed in consideration of the verified explosive model with explosives placed inside the steel pot. Tests were carried out for 3 different designs, which consist of flat plate, twisted plate, and plate with deflector. Elastic and plastic displacement measurements were taken during the tests. LS-DYNA® software was used to perform analyses using the Johnson-Cook material model obtained from Split Hopkinson bar tests for plate materials and the SALE method. The effect of the distance between the plate and the explosive, the behavior of the source during the explosion, the effect of plate geometry, and the comparison with analysis results were investigated as a result of the plate tests.

• Corrugated Fiber Board as a Packaging Material: Experimental and Numerical Analysis of the Mechanical Behavior

  Chandra Sekhar Kattamuri, Madhukar Chatiri, Affiliations, CADFEM Engineering Services India Pvt.Ltd.

  Corrugated Fiber Board (CFB) is a sandwich structure in which several paperboard materials, linerboard is glued to a sine wave shaped core, flute/corrugated medium. CFB packaging is a versatile, economic, light, robust, recyclable, practical and dynamic form of packaging. Boxes made from CFB are commonly used for the packaging of consumer goods, where better resistances to compressive forces, higher bending stiffness, better printability and greater moisture resistance are the most important requirements. The boxes are routinely custom designed to meet specific customer requirements.

• Cost-Effective Sizing of Your HPC Cluster for CAE Simulations

  N. Henkel, S. Treiber (GNS Systems)

  The use of CAE techniques as an integral part of product development has become indispensable in the automotive industry. The investigation of different problems with the help of virtual simulation is used daily by development teams. They need considerable computing power, which is provided by HPC (High Performance Computing) clusters. Typical cluster installations in the automotive industry can range from local resources with 50 to 200 cores up to centralized cloud computing installations with more than 10,000 cores.

• Coupled Crash Live Deployment Simulation Using LS-DYNA® Functional Mock-up Interface

  Ke Dong (General Motors Company), Xiaomeng Tong, Isheng Yeh (ANSYS)

  Advanced driver-assistance systems (ADAS) consist of multiple advanced sensors. Information from these sensors has great potential to improve the performance of existing crash sensing systems. Integrated simulation of the active and passive sensing system is a key enabler to assess the potential benefit. Since ADAS sensing and crash sensing simulation are usually conducted in different environments, co-simulation capability is necessary to bring multiple different environments together to achieve the same simulation goal. In this paper, new co-simulation features have been developed in LS-DYNA using Functional Mock-up Unit (FMU). LS-DYNA is able to generate FMU and co-simulate with other software though Functional Mock-up Interface (FMI). A plugin package “FMU manager” built upon FMI 2.0 standard is provided to LS-DYNA users to implement the FMU import and export. The newly developed features were applied to a coupled live development crash simulation between Matlab/Simulink and LS-DYNA. The crash sensing algorithm was built in Matlab/Simulink and finite element vehicle and airbag models were built in LS-DYNA. Co-simulation between them demonstrated the capability of live deployment simulation under different crash scenarios without modifying the models. In future, the coupled live deployment model will be further integrated with ADAS sensing simulations to explore the benefits of the integrated sensing system.

• COUPLED FEM CALCULATIONS - A CAE TOOL TO IMPROVE CRASH-RELEVANT AUTOMOTIVE BODY COMPONENTS BY LOCAL HARDENING

  Klaus Wolf - Fraunhofer Institute SCAI, Germany, Dr.-Ing. Robert Schilling - Ford-Werke GmbH, Köln, Dr. Jörn Lütjens, Dr.-Ing. Michael Hunkel - IWT Bremen, Dr.-Ing. Thomas Wallmersperger - ISD Universität Stuttgart, Udo Jankowski - Tecosim GmbH, Dirk Sihling - GNS mbH, Klaus Wiegand, Albrecht Zöller - Daimler AG, Martin Heuse Faurecia Autositze GmbH

  In the automotive industry, there is an increasing demand for weight reduction as well as safety requirements. These demands have motivated the use of locally optimized components. This study shows how local rigidity of crash-relevant side rails made of multi-phase steels can be improved by local hardening and thus avoiding an increase of the cross section. At the same time simulation process chains were completed and results validated by experiments. A dedicated software tool for the coupling of a wide range of commercially available FEM software products was developed. Codes for metal forming, heat treatment and crash simulations can now be used in one serial workflow. One major aspect here was the transfer of tensor-like values such as stress or strain states.

• COUPLED FEM CALCULATIONS - A CAE TOOL TO IMPROVE CRASH-RELEVANT AUTOMOTIVE BODY COMPONENTS BY LOCAL HARDENING

  Klaus Wolf - Fraunhofer Institute SCAI, Germany, Dr.-Ing. Robert Schilling - Ford-Werke GmbH, Köln, Dr. Jörn Lütjens, Dr.-Ing. Michael Hunkel - IWT Bremen, Dr.-Ing. Thomas Wallmersperger - ISD Universität Stuttgart, Udo Jankowski - Tecosim GmbH, Dirk Sihling - GNS mbH, Klaus Wiegand, Albrecht Zöller - Daimler AG, Martin Heuse Faurecia Autositze GmbH

  In the automotive industry, there is an increasing demand for weight reduction as well as safety requirements. These demands have motivated the use of locally optimized components. This study shows how local rigidity of crash-relevant side rails made of multi-phase steels can be improved by local hardening and thus avoiding an increase of the cross section. At the same time simulation process chains were completed and results validated by experiments. A dedicated software tool for the coupling of a wide range of commercially available FEM software products was developed. Codes for metal forming, heat treatment and crash simulations can now be used in one serial workflow. One major aspect here was the transfer of tensor-like values such as stress or strain states.

• Coupled Fluid-Structure Interaction Simulation of Prosthetic Heart Valves

  Facundo Del Pin, Iñaki Çaldichoury, Rodrigo R. Paz, Chien-Jung Huang (Livermore Software Technology LLC)

  Artificial heart valves are medical devices that are implanted in patients to replace a diseased native heart valve. They could be classified according to their shape and materials used to manufacture them into mechanical, biological, tissue-engineered and polymeric valves. Approximately 2% of the US population suffer from valvular heart disease (VHD) with the most common causes being aortic stenosis (AS) mostly due to calcification of the aortic valve and aortic valve insufficiency. This paper deals with the numerical simulation of a biological prosthetic aortic valve (AV). This type of valves is composed of three leaflets configured in a complex hemispherical geometry. The leaflets have a variable thickness distribution being thicker at the attachments and free edges and thinner at the belly of the leaflet. Important design parameters for PHVs include effective orifice area, jet velocity, pressure gradient, regurgitation and thrombogenic potential. The objective is to showcase a framework within LS-DYNA® to perform a coupled Fluid Structure Interaction simulation (FSI) of a prosthetic valve and the possible different procedures used to evaluate the design parameters which can be used for a later optimization procedure.

• Coupled Simulation of the Fluid Flow and Conjugate Heat Transfer in Press Hardening Processes

  Uli Göhner, Bruno Boll (DNYAmore GmbH), Inaki Caldichouri (LSTC), Tim Wicke (Volkswagen AG)

  Due to the increasing demands on lightweight design, stiffness and crash performance of automotive body components, the press hardening method becomes widely-used. The high strength of press hardened parts of up to 1.5 GPa results from the nearly complete conversion of austenite into martensite. This microstructural transformation, also known as 'hardening', happens during or subsequently to the forming process. In order to achieve a cooling rate which is high enough to get a martensitic microstructure in all regions of the blank, it has to be ensured that the heat transfer rate from the blank to the tool and inside the tool is sufficiently high. This is achieved at the press hardening lines of Volkswagen through the cooling of the tools with a fluid.

• Coupling FE Software through Adapter Elements: A Novel Use of User-Defined Elements

  Yuli Huang, Andreas Schellenberg, Stephen A. Mahin, Gregory L. Fenves - University of California at Berkeley

  An adapter element provides a versatile and computationally efficient method for coupling several finite element (FE) analysis programs so that the unique modeling and analysis capabilities of each can be utilized simultaneously in the simulation of a complete system. FE software is coupled by (1) using each software's programming interface to embed an adaptor element, and (2) connecting the adapter elements using OpenFresco (Open-source Framework for Experimental Setup and Control). The theory underlying the adapter element is based on the penalty method and communication of information at the nodes of the adapter element connecting a master with a slave program. The implementation and accuracy are then demonstrated using a dynamic analysis of a structural model from earthquake engineering.

• Coupling feedback control loop-based model in Simulink to finite element model in LS-Dyna: Application to reposition forward leaning occupant to upright posture

  A. Soni, S. Schilling, H.Hinrichs, C. Verheyen, M. Grikschat, B. Eickhoff, A. Lucht, A. Cirstea (Autoliv)

  Forward leaning postures have been observed for current car passengers [1] and are expected to occur even more frequently in future autonomous vehicles [2]. For existing restrain systems a strategy to provide optimized protection is to deploy mechatronic belt pre-pretensioner (MBPPT) before the crash targeting to maintain or better prevent possible forward leaning postures, mostly induced through pre-crash vehicle maneuvers [3 - 5]. Where for future restraint systems in highly automated vehicles [6 - 9] an additional load case for MBPPT might become important. Here the airbag restraint system is mounted into the seat, enclosing the upright occupant during deployment. If the occupant is out-of-position, the enclosure of the restrain system might not function optimally. Hence, a pre-triggered MBPPT can be used to bring the occupant back to the upright position before the crash.

• Coupling of Particle Blast Method (PBM) with Discrete Element Method for buried mine blast simulation

  Hailong Teng (LSTC)

  This paper presents two meshless methods: particles blast method (PBM) and discrete element method (DEM). Particle blast method (PBM) is intend to model the gaseous behavior of high velocity, high temperature detonation products. PBM is developed based on corpuscular method (CPM), which has been successfully applied to airbag deployment simulation where the gas flow is slow. For blast simulation where gas flow is extremely high, the equilibrium assumption in CPM is no long valid. By reformulating the particle interaction algorithm, we proposed the PBM that is capable of modelling thermally non-equilibrium system and applied this method for the simulation of blast loading. DEM focus on the modeling of granular media, which might exhibit complex behavior under different condition. Finally, the paper present the coupling of PBM with DEM for buried mine blast simulation.

• Coupling of the EM Solver with Mechanical and Thermal Shell Elements

  Pierre L’Eplattenier, Julie Anton, Iñaki Çaldichoury (LSTC)

  The Electromagnetics (EM) solver of LS-DYNA® has recently been extended to shell elements, in order to solve coupled EM/mechanical/thermal problems on thin plates, which appear in Magnetic Metal Forming and Welding experiments. Due to the magnetic diffusion of the EM fields through the thickness of the plate, which is a very important phenomenon that needs to be precisely solved, the EM part of the simulation still needs a solid mesh with several through thickness elements. This solid mesh, underlying the shell mesh is thus automatically built during the simulation and is used to solve the EM equations. The EM fields are then averaged or summed through the thickness in order to compute equivalent EM fields on the shells, and in particular an equivalent Lorentz force and Joule Heating which are used by the mechanical and thermal solvers. The model is presented and illustrated on some academic and industrial examples. Comparisons between solid and shells are presented.

• Cowper-Symonds material deformation law application in material cutting process using LS-DYNA FE code: turning and milling

  Virginija Gyliene, Vytautas Ostasevicius - Kaunas University of Technology

  Finite element modeling becomes the huge support in understanding technological process. Besides, there are no so much milling process studies, or these studies are simplified to, as orthogonal cutting process. This paper presents experiences results from orthogonal turning and face milling process. These results were taken for FE model validation and material deformation law constants prediction. In both cases some cutting process simplifications were taken, in order to define contact interaction - to execute meso-scale FE analysis. Concerning FE modeling, calculation scheme is presented in order to evaluate removing material load to cutting tool. Secondly, material behaviour characteristics were evaluated, assuming high speed deformation and material failure. Thirdly, cutting tool path is modeled in order to evaluate his influence on chip formation.

• Crash and Impact Simulation of Composite Structures by Using CAE Process Chain

  Ulrich Stelzmann, Madhukar Chatiri (CADFEM GmbH), Thorsten Schütz (Adam Opel AG), Anton Matzenmiller (Univ. of Kassel)

  The objective of this paper is to present a workflow for numerical modeling and simulation of carbon fiber reinforced plastic (CFRP) composite structures including CAE process integration. A computational constitutive model for anisotropic damage is developed to characterize the elastic-brittle behavior of fiber-reinforced laminated composites. The composite damage model is implemented within LS-DYNA® as user defined material subroutine. A CAE process chain which includes the manufacturing side of composites is also presented.

• Crash and Vibration Analysis of rotors in a Roots Vacuum Booster

  Manuel Roth - Pfeiffer Vacuum GmbH, Stefan Kolling - Giessen University of Applied Sciences

  The dynamic behaviour of a roots vacuum booster with two rotors is presented. The dynamic response of the structure is, thereby, investigated using an explicit analysis for the crash behaviour and an implicit analysis for the vibration behaviour. Typically the rotors run from 3000rpm to 3600rpm, but because of a desired rise in power density it is necessary to design rotors for operation at 6000rpm. With increasing rotational velocity the dynamic loading and the inertial forces increase as well. To face this challenge a rotor with less weight was devel- oped. To come to a conclusion about impact behaviour, dynamic deformation and bearing-reactions a crash between the two rotors has been simulated. These results are compared with another rotor which show the potential of weight reduction. The rotor and shaft are made from cast iron. For the material model in the crash analysis, a comparison between Mat Piecewise Linear Plasticity and Mat Gurson JC has been accomplished. To consider tri- axiality a vonMises yield locus is used together with the Johnson-Cook failure criterion in Mat Gurson JC, i.e. damage and its accumulation has been neglected, see [4] and [7]. In an implicit eigenvalue analysis the eigenfrequencies are determined. Roots pumps are assembled in industrial installations, where it is necessary to know the appearing natural frequencies to avoid reso- nance vibrations.

• Crash and Vibration Analysis of rotors in a Roots Vacuum Booster

  Manuel Roth - Pfeiffer Vacuum GmbH, Stefan Kolling - Giessen University of Applied Sciences

  The dynamic behaviour of a roots vacuum booster with two rotors is presented. The dynamic response of the structure is, thereby, investigated using an explicit analysis for the crash behaviour and an implicit analysis for the vibration behaviour. Typically the rotors run from 3000rpm to 3600rpm, but because of a desired rise in power density it is necessary to design rotors for operation at 6000rpm. With increasing rotational velocity the dynamic loading and the inertial forces increase as well. To face this challenge a rotor with less weight was devel- oped. To come to a conclusion about impact behaviour, dynamic deformation and bearing-reactions a crash between the two rotors has been simulated. These results are compared with another rotor which show the potential of weight reduction. The rotor and shaft are made from cast iron. For the material model in the crash analysis, a comparison between Mat Piecewise Linear Plasticity and Mat Gurson JC has been accomplished. To consider tri- axiality a vonMises yield locus is used together with the Johnson-Cook failure criterion in Mat Gurson JC, i.e. damage and its accumulation has been neglected, see [4] and [7]. In an implicit eigenvalue analysis the eigenfrequencies are determined. Roots pumps are assembled in industrial installations, where it is necessary to know the appearing natural frequencies to avoid reso- nance vibrations.

• Crash Impact Modelling Of Security Bollard

  S. K. Tay, B. Lim, S. H. Ng (Ministry of Home Affairs)

  This paper presents the findings from vehicular crash test of a security bollard system, as well as findings generated from numerical simulations using two different loading approaches in LS-Dyna®. The differences between the results from numerical simulations and test observations are explored by examining the velocity-time history profiles of the vehicle and the rotational response of the bollard. The first approach involved a NCAC Chevrolet C2500 finite element pickup model impacting against the bollard model. Contact algorithm was defined to represent the contact of an impacting pickup with the bollard at the collision. In the second approach, the vehicle impact was instead represented by a force pulse generated from the actual crash testing. This approach greatly reduced the computational time required and the results showed good agreement with the vehicle model simulation applied in the earlier approach. These models can be useful tools for design work and provide alternative means to assess the performance of the security bollard system.

• Crash Simulation in Pedestrian Protection

  Susanne Dörr, Hartmut Chladek, Armin Huß - Ingenieurbüro Huß & Feickert

• Crash Simulation of an F1 Racing Car Front Impact Structure

  S. Heimbs, F. Strobl, P. Middendorf, S. Gardner, B. Eddington, J. Key - EADS Innovation Works, Force India Formula One Limited

  Formula 1 motorsport is a platform for maximum race car driving performance resulting from high-tech developments in the area of lightweight materials and aerodynamic design. In order to ensure the driver’s safety in case of high-speed crashes, special impact structures are designed to absorb the race car’s kinetic energy and limit the decelerations acting on the human body. These energy absorbing structures are made of laminated composite sandwich materials - like the whole monocoque chassis - and have to meet defined crash test requirements specified by the FIA. This study covers the crash behaviour of the nose cone as the F1 racing car front impact structure. Finite element models for dynamic simulations with the explicit solver LS-DYNA are developed with the emphasis on the composite material modelling. Numerical results are compared to crash test data in terms of deceleration levels, absorbed energy and crushing mechanisms. The validation led to satisfying results and the overall conclusion that dynamic simulations with LS-DYNA can be a helpful tool in the design phase of an F1 racing car front impact structure.

• Crash Simulation of an F1 Racing Car Front Impact Structure

  S. Heimbs, F. Strobl, P. Middendorf, S. Gardner, B. Eddington, J. Key - EADS Innovation Works, Force India Formula One Limited

  Formula 1 motorsport is a platform for maximum race car driving performance resulting from high-tech developments in the area of lightweight materials and aerodynamic design. In order to ensure the driver’s safety in case of high-speed crashes, special impact structures are designed to absorb the race car’s kinetic energy and limit the decelerations acting on the human body. These energy absorbing structures are made of laminated composite sandwich materials - like the whole monocoque chassis - and have to meet defined crash test requirements specified by the FIA. This study covers the crash behaviour of the nose cone as the F1 racing car front impact structure. Finite element models for dynamic simulations with the explicit solver LS-DYNA are developed with the emphasis on the composite material modelling. Numerical results are compared to crash test data in terms of deceleration levels, absorbed energy and crushing mechanisms. The validation led to satisfying results and the overall conclusion that dynamic simulations with LS-DYNA can be a helpful tool in the design phase of an F1 racing car front impact structure.

• Crash Simulation of KTM “X-BOW” Car Front Impact Structure

  Katharina Fischer (KTM Technologies GmbH), Phelippe Pereira (ESSS), Madhukar Chatiri, Matthias Hörmann, Andre Stühmeyer (CADFEM GmbH)

  The goal of this presentation is to study the structural behavior of the KTM “X-BOW” crash box front impact structure in a 0° impact test against a rigid wall. The energy absorbing crash box is made of laminated composite sandwich material. A “shell-solid-shell” numerical approach is used to model the sandwich composite structure. Shell elements are used for the face layers whereas solid elements are used for aluminum honeycomb core. Shell elements consider the composite layering using *ELEMENT_SHELL_OFFSET_COMPOSITE within LS-DYNA® and will be bonded to the solid elements without node sharing. The composite structure is modeled using *MAT_054 and honeycomb structure is modeled using *MAT_126 within LS-DYNA. For comparison reasons, numerical and experimental results for intrusion, deceleration, velocity and displacement over time are presented.

• Crash Simulation of Mechanical Joints with Automatically Determined Model Parameters based on Test Results and Prediction Algorithms

  S. Sommer, P. Rochel, Fraunhofer IWM, Germany;, M. Guenther, D. Herfert, Society for the Advancement of Applied Computer Science GFaI, Germany;, G. Meschut, P. Giese, Laboratory for material and joining technology LWF, Germany

  The increasing usage of innovative light weight concepts in automobile production leads to the application of different mechanical joining techniques like self-pierce riveting- semi tubular (SPR-ST) and -solid (SPR-S), flow drilling screwing (FDS) and high speed bolt joining (HSB) for multi-material constructions. These mechanical joints are used at positions of car bodies which show high stresses under impact loading. For the prediction of the load-bearing capacity, the failure behavior and the energy absorption in crash simulations complete and reliable models are needed. Therefore experimental results on single joint specimens and simulation of these specimen tests are necessary to determine the model parameters. If this had to be done for all existing sheet metal combinations of all mechanical joints in a body-in-white it would result in a very time and cost intensive process. The aim of the research project “CraSiFue”[1] was to reduce these efforts by developing a forecast algorithm and implementing it in a software. The developed software JoiningLab predicts the joint properties and model parameters of the *CONSTRAINED_ INTERPOLATION_ SPOTWELD (Model 2, “SPR4”) [2], [3] in LS-DYNA® for untested i.e. unknown mechanical joints. This results in saving real tests and accelerates the crash safety investigations especially in the concept phase of construction, where materials, sheet thicknesses and joints are not definitely specified yet.

• Crash Simulation of Public Transport Vehicle Traction Battery

  J. Dohnal, M. Šebík, M. Popovič

  Nowadays, lithium-ion batteries are considered as most efficient source of power for electric vehicles (EVs). With the increasing utilization of EVs, the requirements for higher performance, lower weight and improved safety also growing. These demands can be fulfilled by an improved traction battery design, which consists of decreased battery frame mass or higher number of battery cells. However, with these improvements come several negative aspects, such as higher risk of battery frame intrusion or reduction of space between the cells. Due to these factors, the risk of battery damage is rising and it is crucial to predict and better understand the behaviour of the battery cells during critical situations, such as vehicle crash.

• Crash Test & Simulation Comparisons of a Pickup Truck & a Small Car Oblique Impacts Into a Concrete Barrier

  D. Marzougui, C.D. Kan, and K.S. Opiela (George Mason University)

  Detailed finite element (FE) models of a 2270 kg Chevrolet Silverado and a 1100 kg Toyota Yaris are used as surrogates for barrier crashworthiness under the new Manual for Assessment of Safety Hardware (MASH). MASH requires assessment of barriers for both large and small vehicles, hence the use of 2270P and 1100P test vehicles. Impacts of these two vehicles into a New Jersey-shaped concrete median barrier were simulated and compared to full-scale crash tests. The objectives of this effort included (1) demonstrating the viability of the FE models for the new MASH crashworthiness evaluation, and (2) describing the application of the newly developed roadside verification and validation (V&V) procedures to compare simulation results and crash test data. Comparisons of the simulation results and data derived from crash tests using “traditional” methods suggested that the models provided viable results. Further comparisons using the new V&V procedures provided (1) a structured assessment across multiple factors reflected in PIRT tables and (2) statistical comparisons of the test and simulation results allowing a more robust validation than previous approaches. These comparisons further confirmed that the new vehicle models were able to effectively replicate impacts for MASH tests and that the V&V procedures provided useful insights and increased confidence in the models.

• Crash Testing and Simulation of a Cessna 172 Aircraft: Pitch Down Impact onto Soft Soil

  Edwin L. Fasanella (National Institute of Aerospace), Karen E. Jackson (NASA Langley Research Center)

  During the summer of 2015, NASA Langley Research Center conducted three full-scale crash tests of Cessna 172 (C-172) aircraft at the NASA Langley Landing and Impact Research (LandIR) Facility. The first test represented a flare-to-stall emergency or hard landing onto a rigid surface. The second test, which is the focus of this paper, represented a controlled-flight-into-terrain (CFIT) with a nose-down pitch attitude of the aircraft, which impacted onto soft soil. The third test, also conducted onto soil, represented a CFIT with a nose-up pitch attitude of the aircraft, which resulted in a tail strike condition. These three crash tests were performed for the purpose of evaluating the performance of Emergency Locator Transmitters (ELTs) and to generate impact test data for model validation. LS-DYNA ® finite element models were generated to simulate the three test conditions. This paper describes the model development and presents test-analysis comparisons of acceleration and velocity time-histories, as well as a comparison of the time sequence of events for Test 2 onto soft soil.

• Crash Testing and Simulation of a Cessna 172 Aircraft: Hard Landing Onto Concrete

  Karen E. Jackson (NASA Langley Research Center), Edwin L. Fasanella (National Institute of Aerospace)

  A full-scale crash test of a Cessna 172 aircraft was conducted at the Landing and Impact Research Facility at NASA Langley Research Center during the summer of 2015. The purpose of the test was to evaluate the performance of Emergency Locator Transmitters (ELTs) that were mounted at various locations in the aircraft and to generate impact test data for model validation. A finite element model of the aircraft was developed for execution in LS-DYNA® to simulate the test. Measured impact conditions were 722.4-in/s forward velocity and 276-in/s vertical velocity with a 1.5° pitch (nose up) attitude. These conditions were intended to represent a survivable hard landing. The impact surface was concrete. During the test, the nose gear tire impacted the concrete, followed closely by impact of the main gear tires. The main landing gear spread outward, as the nose gear stroked vertically. The only fuselage contact with the impact surface was a slight impact of the rearmost portion of the lower tail. Thus, capturing the behavior of the nose and main landing gear was essential to accurately predict the response. This paper describes the model development and presents test-analysis comparisons in three categories: inertial properties, time sequence of events, and acceleration and velocity time-histories.

• CRASH-SIMULATION OF HAT-SECTIONS RELIABILITY OF THE NUMERICAL MODEL

  Paul Du Bois - consulting engineer, Thomas Frank - Daimler-Chrysler

• Crash-tests simulations by LS-DYNA code on the HPC AMD64 Cluster

  Prof. Nikolay Shabrov, Prof. Yuri Mikhailov, Iliya Lopatukhin,- Saint Petersburg State Polytechnical University, Russia, Dr. Evgeniy Shmelev, Dr. Sergey Kurdyuk - AVTOVAZ Company, Russia

  Crash-test simulations of the car models by LS-DYNA code are carried out on the HPC 16 CPU AMD64 Opteron processors Cluster. Simulations are based on the large 3D finite element car models that contain more then one million DOF. Architecture and benchmark of the HPC 16 CPU AMD64 Cluster were tested by engineering applications with commercial engineering codes LS- DYNA instead of synthetic benchmark. For this purposes several tasks were taken from www.topcrunch.org. The tasks named “3 Vehicle Collision” and “Neon”. Benchmark tests have shown pretty good results for such type of industrial problems and confirmed that Opteron processor on AMD platform is preferable to Itanium processor on Intel platform. LS-DYNA code was used for crash analysis of real modern cars produced by AVTOVAZ in Russia. HyperMesh software was used to create finite element mesh and for a pre- processor for LS-DYNA solver. To visualize simulations as 3D virtual reality objects crash analysis results obtained on HPC Cluster were imported on 3D Virtual reality system named WorkBench. WorkBench 3D virtual reality system contains soft screen, two multimedia projectors, computer with dual heads graphics adapter and tracking system Flock of Birds. COVISE software was used for visualization of CAD models of the cars and crash analysis results as 3D virtual reality objects.

• CRASHWORTHINESS ANALYSIS OF A LOCK GATE IMPACTED BY THREE DIFFERENT RIVER SHIPS

  Hervé Le Sourne, Stéphane Paboeuf, Guy Babaud - French Shipbuilding Research Institute, Jean-Claude Rodet - ECMT

  This paper presents a study of the crashworthiness of the Pierre Bénite lock gate using a FEM approach. This gate situated in the Rhône river (south of Lyon) is collided by three different river ships : - a 6000 DWT convoy of barges with an initial velocity of 1m/s, - 3500 DWT carrier Rhône-Liner with an initial velocity of 1m/s, - a 2200 DWT passenger vessel with initial velocities of 1m/s and 2m/s. An analytical elastic analysis of the crashworthiness of a lock gate was carried out by J.C Rodet for the «Compagnie Nationale du Rhône». This analysis showed that : - the kinetic energy of a river ship which impacts a lock gate with a velocity of 1m/s is not entirely dissipated by the elastic energy of the lock gate, - the lock gate elastic response may result in dangerous reaction forces at the supporting chains, - empirical or analytical methods [2] generally used to determine the impact forces and resulting indentations of struck ship hulls may be applied to the lock gate but they have to be validated by a non-linear finite element analysis. An overview of the elastic analysis is presented in section 2 below. As we found that an elastic analysis was insufficient to quantify the damage, we decided to conduct a numerical analysis (section 3).

• Crashworthiness Analysis of Finite Element Truck Chassis Model Using LS-DYNA

  Yucheng Liu - University of Louisiana

  This paper presents a detailed multi-purpose finite element model of a light duty truck chassis and evaluates this model in computational simulations of full frontal, offset frontal, and corner impacts. The simulation results are analyzed which correctly describe the characteristics and performance of a truck chassis during under impact scenarios. Through the validation and computational simulations, the presented model is proved to be computationally stable, reliable, repeatable, and useful for vehicle crashworthiness analysis. LS-DYNA is used for finite element modeling and crashworthiness analysis

• Crashworthiness and Sensitivity Analysis of Structural Composite Inserts in Vehicle Structure

  Chung-Kyu Park, Cing-Dao Kan, Pradeep K. Mohan - The George Washington University, Steven W. Reagan - L & L Products Inc., Balachandra R. Deshpande - SimaFore Inc.

  This study is focused on identifying influential parameters in numerical analysis of structural composite inserts in vehicle structure. A 3-point bending test of a simplified steel-composite beam structure is conducted to evaluate the crashworthiness of composite insert in steel structure. Empty sections of the beam structure are filled with composite insert and foam filler. From physical 3-point bending tests, it is identified that the two critical behaviors of composite insert and foam filler greatly affect the strength level of steel-composite beam structure. Some influential parameters to achieve an accurate simulation model are studied. Finally, future steps of research work are indicated.

• Crashworthiness Design of Vehicle Structures via Equivalent Mechanism Approximations

  Karim Hamza, Kazuhiro Saitou - University of Michigan

  A new method for crashworthiness optimization of vehicle structures is presented. In the new method, early design exploration is done by the optimization of an equivalent mechanism approximating a vehicle structure. An equivalent mechanism (EM) is a network of rigid bodies connected by prismatic and revolute joints with special nonlinear springs. These springs are tuned to mimic the force-displacement characteristics of thin-walled beams often found in the vehicle body structures. The EM models can be regarded as a super-set of lumped models and thus they are capable of providing better insight to the design issues. Proper selection of the nonlinear spring parameters is essential to successful implementation of the EM models. Identification of the spring parameters involves pre-compilation of databases of the crash characteristics of frequently used structures via LS-DYNA simulations. The pre-compiled databases and EM models are then used in the initial design phase in order to explore the crash deformation patterns and identify the good crash mode (CM). Once the good crash mode is identified, it becomes the target for detailed design stage which uses higher accuracy LS-DYNA models of the vehicle structures. A case study involving design optimization of the mid and lower rails of a vehicle subjected to frontal crash test conditions is presented. The case study demonstrates the effectiveness of the proposed method.

• Crashworthiness of Aluminium Structures Modelling and Validation

  M. Langseth - Norwegian University of Science and Technology

  Lightweight materials such as aluminium offer the automotive industry an opportunity to design and manufacture high-performance vehicles that are safe, energy-efficient and environmentally friendly, and much lighter than traditional designs. However, the introduction of these materials will challenge the automotive design engineers to explore and develop new solutions in design and production technology in order to fully realize the potential that can be gained in the interaction between these materials, product/structural design and the manufacturing process. Even though aluminium is an “old” material, it is relatively new as a load-carrying material in the automotive industry. This implies that material producers and parts suppliers have to develop new knowledge about these materials to gain an increased market share. In order to meet the future challenges with respect to the use of aluminium as a structural material in the automotive industry, the product development to day is increasingly carried out in virtual environments by using computational mechanics. Even though great advances have been made in modelling, the designer must still use knowledge about the physical mechanisms controlling the product performance. The designer must also know what simplifications can be made in the modelling and still retain sufficient reliability and accuracy. At all levels of modelling, experimental validation of the numerical models to be used is required before the models are accepted. In the period 2007-2014 the SIMLab research group at NTNU is defined by the Research Council of Norway as a Centre for Research based Innovation (www.ntnu.no/simlab). One of the objectives with the centre is to provide the industrial partners with reliable and robust engineering models of aluminium to be used in crash analyses. Thus the present presentation will focus on some of the modelling activities carried out in the centre as well as the validation of these models and try to highlight some of the needs and challenges mentioned above by using aluminium in the automotive industry. In the introduction an overview of aluminium as a structural material will be given and the strong and weak points about the material will be defined. Examples will here be given on typical mechanical properties that have to be taken into account in the developed models in order to have good and reliable predictions. Then the use of aluminium in the automotive industry will be discussed as an introduction to the models developed by the SIMLab group on thermoplastics, aluminium foams, self-piercing rivets, aluminium extrusions and plates, aluminium castings and magnesium. Finally the developed models for aluminium and self piercing rivets will be validated against component tests in the laboratory. For the self-piercing riveting activity an engineering and research strategy will be shown in order to develop a shell-based model where an interaction between process and component testing and process and component numerical simulations are carried out.

• Crashworthiness of Aluminium Structures Modelling and Validation

  M. Langseth - Norwegian University of Science and Technology

  Lightweight materials such as aluminium offer the automotive industry an opportunity to design and manufacture high-performance vehicles that are safe, energy-efficient and environmentally friendly, and much lighter than traditional designs. However, the introduction of these materials will challenge the automotive design engineers to explore and develop new solutions in design and production technology in order to fully realize the potential that can be gained in the interaction between these materials, product/structural design and the manufacturing process. Even though aluminium is an “old” material, it is relatively new as a load-carrying material in the automotive industry. This implies that material producers and parts suppliers have to develop new knowledge about these materials to gain an increased market share. In order to meet the future challenges with respect to the use of aluminium as a structural material in the automotive industry, the product development to day is increasingly carried out in virtual environments by using computational mechanics. Even though great advances have been made in modelling, the designer must still use knowledge about the physical mechanisms controlling the product performance. The designer must also know what simplifications can be made in the modelling and still retain sufficient reliability and accuracy. At all levels of modelling, experimental validation of the numerical models to be used is required before the models are accepted. In the period 2007-2014 the SIMLab research group at NTNU is defined by the Research Council of Norway as a Centre for Research based Innovation (www.ntnu.no/simlab). One of the objectives with the centre is to provide the industrial partners with reliable and robust engineering models of aluminium to be used in crash analyses. Thus the present presentation will focus on some of the modelling activities carried out in the centre as well as the validation of these models and try to highlight some of the needs and challenges mentioned above by using aluminium in the automotive industry. In the introduction an overview of aluminium as a structural material will be given and the strong and weak points about the material will be defined. Examples will here be given on typical mechanical properties that have to be taken into account in the developed models in order to have good and reliable predictions. Then the use of aluminium in the automotive industry will be discussed as an introduction to the models developed by the SIMLab group on thermoplastics, aluminium foams, self-piercing rivets, aluminium extrusions and plates, aluminium castings and magnesium. Finally the developed models for aluminium and self piercing rivets will be validated against component tests in the laboratory. For the self-piercing riveting activity an engineering and research strategy will be shown in order to develop a shell-based model where an interaction between process and component testing and process and component numerical simulations are carried out.

• Crashworthiness of an Electric Prototype Vehicle Series

  F. Huberth, S. Sinz, S. Herb, J. Lienhard, M. Jung, K. Thoma - Fraunhofer EMI, Freiburg, K. Hochberg, C. J. Fleig - University of Applied Sciences Offenburg

  The Shell Eco-marathon (SEM) is a challenge for student teams to develop energy-efficient vehicles and demonstrate the fuel efficiency of their prototypes. In Europe, this takes place at the Lausitz Ring in Germany. Since 2009, the Schluckspecht team has taken part in the Urban Concept category of the SEM. The specification of the vehicles which start in the Urban Concept Group requires resemblance to roadworthy cars. In the last quarter of 2009, the University of Applied Sciences Offenburg (FHO) where the team is located and the Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI, Freiburg, set up a cooperation to improve safety of the prototype Schluckspecht City. Fraunhofer EMI deals with physical-technical aspects of high-speed, mechanical, and fluid-dynamic processes. This includes experimental and numerical analyses of crash, impact and penetration processes in a broad range of speeds from 10 m/s to 10,000 m/s, the response of structures to shock loads, dynamic material response and vehicle safety.

• Crashworthiness of Composite Structures with Various Fiber Architectures

  Nageswara R. Janapala, Fu-Kuo Chang - Stanford University, Robert K. Goldberg, Gary D. Roberts, Karen E. Jackson - NASA Glenn Research Center

  Advanced textile composite structures, such as braids and fabrics, are showing promising characteristics for energy absorption. However, modeling of these composite structures is quite challenging because of their complicated architecture, varied fiber/matrix combinations, and the failure mechanisms associated with them. Unfortunately, none of the existing material models is capable of simulating diverse failure behaviors observed during crushing of these composite structures. This paper will present a material model that can simulate the crushing response of composite structures with different fiber architectures. The material model identifies a smallest repeatable unit (i.e. unit-cell) within the textile composite and considers fiber modeling, strain rate effect, tow rotation and progressive failure criteria at tow level. The composite tow is assumed to be transverly isotropic, and modeled using an elastic- viscoplastic constitutive law. A DyCrash (Dynamic Crash) module is developed and implemented in LS-DYNA® as a user routine. The module is currently being validated for Kevlar fabrics. Results are presented for 00/900 and ± 450 Kevlar fabric coupons. A methodology is developed to back calculate the yarn properties from available Kevlar fabric test data using DyCrash.

• Crashworthiness of Conventionally Designed Railway Coaching Stock and Structural Modifications for Enhanced Performance

  X. Xue - AEA Technology Rail, F. Schmid - University of Sheffield

  In this paper, the authors present a crashworthiness assessment of a conventionally designed railway passenger vehicle and suggest modifications for its improvement. The analytical approach consisted of two stages. Firstly, the crashworthiness of the coach was assessed by simulating a collision between the coach and a rigid wall. Then, after analysing the structural weaknesses, the design of the coach was modified and simulated again in the same scenario. It was found that bending or jack-knifing is a main form of failure in conventionally designed rail vehicle structures and components. The coach design, as modified by the authors, overcomes the original weaknesses and shows the desired progressive collapse behaviour in simulation. The conclusions have general relevance and suggest the need for a rethink of some aspects of rail vehicle design.

• Crashworthiness Optimization in LS-OPT: Case Studies in Metamodeling and Random Search Techniques

  Nielen Stander, Willem Roux - Livermore Software Technology Corporation, Mathias Giger, Marcus Redhe - University of Linköping, Sweden, Nely Fedorova - Snezhinsk Institute of Physics and Technology, Russia, Johan Haarhoff - University of Pretoria, South Africa

  This crashworthiness optimization study compares the use of three metamodeling techniques while using a sequential random search method as a control procedure. The three methods applied are (i) the original Successive Linear Response Surface Method, (ii) the Neural Network method and (iii) the Kriging method. It is shown that, although NN and Kriging seem to require a larger number of initial points, the three metamodeling methods have comparable efficiency. The random search method is surprisingly efficient in some instances, but by nature much less predictable.

• Crashworthiness Simulation Using Coupled Meshfree/Finite Element Formulations in LS-DYNA

  Hui-Ping Wang, Ye-Chen Pan, Yi-Pen Cheng - General Motors Corporation

  This paper demonstrates applications of a coupled meshfree/finite element solver of LS-DYNA in the analysis of crashworthiness components. Two examples are employed in the study. The first one is a European side impact dummy component test problem. It is used to show the robustness of the coupled meshfree/finite element solver in handling large deformation since the finite element analysis of this problem fails due to numerical instability caused by negative element volume. By applying the meshfree formulation to the large distortion area, we successfully complete the simulation and obtain very reasonable solutions. The second problem is an engine cradle drop tower test. Various background meshes are created for this problem to study the effect of different element connectivity on accuracy of the meshfree solutions. The study shows that, with the same particle distributions the meshfree analysis yields more consistent solutions than the finite element analysis when the background connectivity varies.

• CRASHWORTHINESS: NUMERICAL SIMULATION OF VEHILCE-STEEL POLE CRASH

  Magdy Samaan - University of Windsor, Ahmed Elmarakbi - University of Toronto, Khaled Sennah - Ryerson University

  The objective of this paper is to generate research information to enhance energy absorption characteristics in transportation infrastructures involved in vehicle crash accidents. A finite-element computer model, using the available LS-DYNA software, was developed to simulate crashes of a vehicle and a traffic light steel pole in frontal impact. The finite-element vehicle model was based on a 1991, 4-door, Ford Taurus. The steel pole was modeled using shell elements to capture the three-dimensional effect of the structure. Four configurations of steel pole supports were examined. The first support type was the typical steel base currently used over concrete foundation, with anchor bolts as specified by the Canadian Highway Bridge Design Code of 2000. The second support type was similar to the first one but with stressed springs between the nuts, over and under the steel base plate. In the third case, rubber-bearing pads were utilized between the base plate and the concrete foundation. In the fourth case, the steel pole was embedded into the soil with a certain embedding length (no concrete foundation is used). The structural response focused on energy absorption as well as the deformation of the steel pole. The fourth system of steel pole supports was proved to be strong enough to offer protection during minor impacts and under service loading, and to remain flexible enough to avoid influencing vehicle occupants, thus reducing fatalities and injuries resulting from the crash.

• Crashworthy Design of Composite Structures Using CAE Process Chain

  M. Chatiri (Cadfem), T. Schütz (Adam Opel), Prof. A. Matzenmiller (University of Kassel)

  The materials used in automotive industry should play key role in overcoming the current challenging demands such as increased global competition, need for vehicles with highest efficiency, reduction in costs, stringent environmental and safety requirements. This eventual usage of lighter materials mean lighter vehicles and low greenhouse gas emissions. Composites are getting more recognition and hence being used increasingly in the automotive industry due to their excellent weight specific characteristics such as strength and stiffness.

• Creating a complete crash model with GNS. High accurate Barriers, handy preprocessing with dummy positioning and fast tailored result analysis

  C. Kaulich, L. Benito Cia (GNS)

  The current transformations in the automotive industry are forcing all car manufacturers to check their processes constantly and repeatedly for economic efficiency. Regarding the areas of body development, vehicle safety and occupant as well as pedestrian protection, economic efficiency can only be achieved through a high degree of automation in virtual product development. Such a degree of automation is only feasible, if the software used and the integrated models are well coordinated. In this presentation it will be shown how a high precision barrier model and several dummy models can be combined and positioned for any vehicle model within the pre-processor Generator4 with ease. Both direct positioning tools and simulation driven ones can be fully automated in a simple way. Information on positioning and kinematic relationships can be taken directly from the input files. This simplifies the following processes and reduces the error rate due to less manual data input. Generator4 is then able to directly start the simulation with LS-Dyna or other solvers.

• Creating Machine-Learning-Friendly Training Data from Crash Simulation Data

  Sarah Zenne, Joachim Sprave, Markus Stoll

  A method is presented for generating training data from FEM meshes based on element prop-erties. Learning at the element level is often indicated when larger structures, especially parts, are too inhomogeneous in size or geometry. At the element level, quality metrics and other infor-mation are gathered from the neighborhoods of elements, just as convolutional neural networks for image processing gather information from the neighborhoods of pixels. But in general, neigh-borhoods of elements are not as well structured as pixels in images. Instead, they form irregular graphs which cannot be processed by standard Neural Network (NN) architectures directly.

• Creation and Validation of Material Cards for Aluminium Sheet Metal Materials

  R. Hennig (Aleris Rolled Products Germany)

  While many simulation programs contain sufficient material cards for most of the steel materials, the aluminum cards often aren’t available yet. Therefore many of the aluminum processing suppliers have to create their own cards but aren’t willing to change them with other suppliers or customers because of the necessary high effort to get them. This leads to a higher uncertainty of the ability to process aluminum sheet metal materials in the automotive industry especially for small and medium-sized enterprises which aren’t able to create their own cards and simulate their forming processes with sufficient reliability and prevents a higher distribution of aluminum sheets in the market in general. Therefore Aleris - one of the leading Aluminum Suppliers in the world - has decided to create their own material cards for all of their sheet materials to help their customers to simulate their forming processes with the Aleris aluminum sheets with ease and reliability.

• Creation of 3D geometry from topology optimization results, for thin-walled and casted parts

  A. Kaloudis, A. Poulias (BETA CAE Systems)

  The use of topology optimization gives us the capability to create an optimal design for a product, taking into consideration a set of predefined constraints, under certain load cases to which it is subjected. However, its results exhibiting jagged and/or no well-defined boundaries, lead into difficulties, regarding the interpretation of these results into proper CAD geometry, which subsequently could be used downstream in the CAD based product development process or could be parametrized and further optimized. Moreover, the manufacturing process, that will be followed to build the parts or the structure, adds an extra variable and increases the degree of difficulty to the task of creating adequate CAD geometry.

• Creep Modeling Of Plastic Components in Sealed Connectors

  H. E. Miled (Delphi Connecting Systems)

  This work address the sealed connectors for engine compartment in particular high pin count housings and pin header. Silicon components, such as grommets and interfacial seals, are used and designed to ensure good contact pressure on plastic components and thus good sealing performance. On several products, we noticed a deformation of plastic housings, in contact with seals, that leaded to a loss of sealing performance. This deformation is the sum of an instantaneous deformation, and a creep deformation. The instantaneous deformation results from elasto-plastic behavior during assembly and thermal change (e.g at 125°C) that leads to seals expansion and weaker plastic mechanical properties. Whereas the creep deformation results from the visco-plastic behavior and evolves with time under a constant loading and a constant temperature. This paper describes and illustrates the numerical approach, used to identify the ratio of instantaneous and creep deformations on a given connectors. Simulation results on lsdyna, with sweetable models, are compared to experimental testing

• Creep study of expanded polystyrene used in Refrigerator packaging

  S. Jagtap, D. Thorat, D. Chhetri, S. Vishwakarma (Whirlpool of India), M. Fiori (Whirlpool Technical Center)

  The efficient staging and storing of home appliances in warehouses are critical to avoid human injuries and huge losses to the company. After manufacturing the packaged product needs to be stored for a particular duration in the warehouse before it’s shipped out to suppliers. For optimum space management, those products are stacked one over the other. So it is important to have a robust packaging design to ensure even distribution of stacked product loads maintains their stability. Considering the constant loading over a longer period there is a high possibility of creep effects in packaging material, and it becomes even more crucial when packaging material is Expanded Polystyrene (EPS). So it's imperative to study material creep behavior in designing product packaging. In this study creep behavior of EPS material is evaluated with standard test setup, where precise measurement is done to get creep curves. The results were obtained for long-term constant compressive loading at different stress levels for multiple material densities, at ambient temperature 23°C.

• Cross-Platform Co-Simulation for Vehicle Safety Analysis

  Xiaomeng Tong, Isheng Yeh (Livermore Software Technology, an ANSYS Company)

  Cross-platform co-simulation is gaining more popularity nowadays for vehicle safety analysis. Essential elements, such as ADAS (advanced driver-assistance system) sensors, vehicle dynamics, occupant posture, and controller, can be individually solved in each software and effectively connected to the toolchain. The concept of co-simulation well suits the vehicle integrated safety analysis, which consists of both (1) the active safety features, such as autonomous emergency braking, lane keeping, etc., and (2) the passive safety features, such as the airbag, seatbelt pretensioner, etc. The co-simulation also extends the vehicle safety analysis from the traditional in-crash to a more comprehensive inclusion of pre-crash so as to evaluate the dummy posture and injury more precisely. To achieve this purpose, LS-DYNA® develops a co-simulation feature based on the Functional-Mockup-Interface (FMI), which allows LS-DYNA to remotely exchange data with any 3rd party software supporting this standard. Two cases are demonstrated hereby: the first is a passive safety co-simulation between LS-DYNA and MATLAB, where MATLAB controls the seatbelt pretension force, timing and the airbag deployment in LS-DYNA; the second case is the integrated safety case focusing on the active seatbelt control, where ANSYS VRX Driving Simulator solves the vehicle dynamics, and MATLAB provides the controller of braking/acceleration in VRX as well as the seatbelt/airbag in LS-DYNA. Both cases reveal that a more accurate occupant posture and significant improvement of occupant injury can be achieved by optimizing the active/passive safety features through the co-simulation.

• Cross-Sectional Warping in Sheet Metal Forming Simulations

  T. Willmann (University of Stuttgart), A. Wessel (Fraunhofer IWM), T. Beier (thyssenkrupp), A. Butz (Fraunhofer IWM), M. Bischoff (University of Stuttgart)

  For most sheet metal forming simulations, shell elements that consider a reduced stress state, in particular, assuming a zero transverse normal stress 𝜎33 and neglecting the shear stress components 𝜎13 and 𝜎23 in the yield function, are used. Moreover, certain kinematic assumptions, like cross-sectional material fibers being assumed to remain straight during deformation, are typically applied. However, for some applications, like bending with small radii and thick sheets, this approach is not a workable solution to obtain accurate and reliable results, since the prerequisites that justify the aforementioned kinematic assumptions are not met anymore.

• Cure History Dependent Viscoelastic Modeling of Adhesively Bonded Joints using MAT_277 in LS-DYNA®

  Akshat Agha, Fadi Abu-Farha, Rakan Alturk, Clemson University - International Center for Automotive Research, Greenville, SC, USA;, Tim Welters, Georges Romanos, Henkel Corporation, Düsseldorf, Germany

  The effects of Coefficient of Thermal Expansion (CTE) mismatch in multi-material adhesive joints, induced during the manufacturing process, are expected to hinder the peak performance of the adhesive in the service life of the vehicle. With a goal to estimate these effects, this paper attempts to model the curing phenomenon of an adhesive and predict its mechanical properties using MAT_277 material model available in LS-DYNA, which serves as a good starting point towards modeling the cure history dependent viscoelastic behavior of adhesives. The adhesive is used to join two substrates of dissimilar metals and tested to capture the relative displacement of substrates. The experiments are performed on a specialized setup, which is built to perform experiments on lap shear joints.

• Current and future developments of LS-DYNA I

  Dr. Hallquist J. O. - Livermore Software Technology Corp.

  LSTC’s Perspective on the future Version 970 status Recent developments for crash Arbitrary Lagrangian-Eulerian Developments Implicit Developments EFG (Mesh-free) Developments MPP Outlook

• Current and future developments of LS-DYNA II

  Dr. Hallquist J. O. - Livermore Software Technology Corp.

• Current and Future Developments of LS-DYNA

  Dr. J. O. Hallquist - Livermore Software Technology Corporation

• Current features and developments of LS-PREPOST

  P. Ho - Livermore Software Technology Group

• Current Features of LS-PREPOST

  LSTC

• Current Status of LS-DYNA ® Iso-geometric Analysis in Crash Simulation

  Yijung Chen, Shih-Po Lin, Omar Faruque, Jim Alanoly, Mohammed El-Essawi, Ragu Baskaran (Ford Motor Company)

  This paper reports a current implementation of Iso-geometric Analysis (IGA) in crash simulation. Several crash critical enhancements of IGA had been proposed by Ford and implemented by LSTC. Such examples include the fix of shear-locking of Mindlin-Reissner shell and the implementation of attached node to NURBS patch. The benchmark of IGA Mindlin-Reissner shell reveals the existence of mild shear-locking in the default full integration scheme. This problem had been fixed in the new option of selected reduced integration. The non-interpolatory nature of NURBS control points makes them not suitable for CAE nodal operations. The attached-node feature to NURBS patch was then created to output nodal time history and to apply nodal force or nodal constraint for IGA model. To exhibit the superiority of IGA performance, an example of curved component was developed to demonstrate the benefit of exact geometry in computational analysis. A crash-can sled model with fixed rigid wall was built to test IGA features which used in frontal crash. This sled model contains all required ingredients – IGA contacts rigid wall, IGA self-contact, meshless spot-welds connecting to NURBS patch, rigid body-IGA connection, gravity loading, nodal acceleration and the compatibility of *MAT_024 plasticity model with IGA model – to evaluate the performance of IGA in crash safety analysis. The implementation of Bezier extraction to interface with other advanced spline functions and the development of IGA-FE hybrid model for future crash safety development are also addressed.

• Current Status of LS-PrePost and the New Features in Version 4.2

  P. Ho (LSTC)

  LS-PrePost is an advance pre and post-processor that is delivered free of charge with LS-DYNA. It is designed and developed specially to support LS-DYNA in pre-processing and post-processing all in one single code. The main features in the pre-processing include CAD geometry creation and manipulation. A wide range of meshing capabilities including automatic mesh generation for surfaces, hexahedron and tetrahedron elements generation for solid

• Current Status of Subcycling and Multiscale Simulations in LS-DYNA®

  Thomas Borrvall (DYNAmore Nordic AB), Dilip Bhalsod, John O. Hallquist, Brian Wainscott (LSTC)

  Subcycling in explicit finite element simulations refers to the technique where a model is partitioned in levels of the characteristic time step of its constituting finite elements. Each sub model is then integrated independently of the others using a time step that pertains to that specific sub model, with the exception of special treatment at the interface between sub models. With the subcycling option in LS-DYNA, up to seven sub models are automatically generated, each integrated in steps of 1, 2, 4, 8, 16, 32 and 64 times the smallest characteristic time step of the entire model. To allow more control of the partition, the user may manually designate parts to be integrated at specific time steps. This is sometimes referred to as multiscale since it is mainly intended for detailed modeling of critical components in a large simulation model, i.e., different time scales are used in order to save CPU time. This paper presents the current status of this feature in LS-DYNA, including a detailed description of the involved algorithms and presentation of small to large scale numerical examples.

• Curve Comparison using esiCORA

  M. Sommer, M. Seshadri (ESI)

• Curved Barrier Impact of a NASCAR Series Stock Car

  Eric A. Nelson, Li Hong - Altair Engineering

  A detailed finite element model of a NASCAR Series stock car has been developed by Altair Engineering and used to study a curved barrier impact. This paper will review some of NASCAR’s capabilities in the area of motor sports safety research and provide an overview of a study that has been performed by Altair Engineering. Specifically, the author will compare and contrast results from a curved barrier impact in 3 different scenarios: • Controlled full vehicle crash test • On-track incident with very similar impact conditions • Detailed finite element analysis using LS-DYNA

• Damage and Failure Model Characterization for High Strength AA6000 Automotive Aluminium Alloys

  Sebastijan Jurendic, Novelis Deutschland GmbH, R&D Centre Göttingen, Germany;, Richard Burrows, David Anderson, Novelis inc., Novelis Global Research and Technology Center, Kennesaw, USA

  In this work we compare two different approaches for characterizing the GISSMO damage and failure model for high strength AA6000 series aluminium alloys using LS-DYNA®. The aim is to determine a consistent and reliable procedure for determining failure related mechanical properties of the material for use in automotive crash applications. The two approaches considered here are: a) an inverse numerical technique using LS-OPT® to solve an optimization problem and b) direct measurement of material data using specific mechanical tests and digital image correlation. The material data determined by both approaches is compared and evaluated for accuracy using the GISSMO test geometries and a comparison between shell elements and solid elements is given.

• Damage Evolution and Energy Absorption of FRP Plates Subjected to Ballistic Impact Using a Numerical Model

  L.J. Deka, S.D. Bartus, U.K. Vaidya - University of Alabama at Birmingham

  High velocity transverse impact to laminated fiber reinforced composites is of interest in military and structural applications. Damage evaluation of the targets during impact based upon experimental work can be prohibitively expensive. However recent advances in the field of numerical simulation provide a means of predicting the performance characteristics of layered materials for ballistic protection. There is however, limited information about the ballistic response of reinforced thermoplastic composite materials. The overall objective of this work is to investigate the behavior of a plain weave laminated composites of varying thicknesses under high velocity impact both from an experimental and modeling view point. To analyze this problem, a series of ballistic impact tests have been performed on plain weave E-glass/polypropylene laminated composites of different thicknesses with a 0.50 caliber cylindrical shaped flat nose projectiles. A gas gun with a sabot stripper mechanism is employed to impact the panels. To analyze the perforation mechanism, ballistic limit and damage evaluation, an explicit three- dimensional finite element code LS-DYNA is being used. Selecting proper material models and contact definition is one of the major criteria for accuracy of the numerical simulation. During high velocity impact, composite laminates undergo progressive damage failure and hence, Material Model 161, a progressive failure model based on Hashin’s criteria, has been assigned to predict failure of the laminates. The projectile is modeled using a Material Model 3 (MAT_PLASTIC_KINEMATIC). The laminates and the projectile are meshed using brick elements with single integration points. The impact velocity ranged from 187 to 332 m s-1. A good correlation between the numerical and experimental results has been drawn in terms of predicting ballistic limit, delamination and energy absorption during impact.

• Damage in Rubber-Toughened Polymers – Modeling and Experiments

  M. Helbig DYNAmore), T. Seelig (Karlsruhe Institute of Technology)

  The superior ductility and toughness of rubber-toughened polymers relies on microscale deformation and damage mechanisms such as void growth, shear yielding and crazing. In the present work, a micromechanical model for the inelastic deformation behavior of rubber toughened polymers is developed which focuses on the effect of crazing, i.e. the formation of localized cohesive zones of fibrillated material.

• Damage modeling of aluminum casting components considering defect distribution for crashworthiness prediction

  F. Andrieux, C. Frie , D. Sun (Fraunhofer IWM)

  Aluminum die casting components are widely used in vehicle constructions because of their good compromise between weight reduction and improvement of mechanical properties. The complex geometries of these components with inhomogeneous defect distribution are a relevant issue, as material with higher defect content shows lower fracture strain. It makes the analysis of the damage behavior for crash simulation more challenging. An extensive experimental investigation is required to quantify the scatter as well as the development of a suitable material model to describe it.

• Damage modelling of a TRIP steel for integrated simulation from deep drawing to crash

  Dr. Dong-Zhi Sun, Dr. Florence Andrieux - Fraunhofer Institute for Mechanics of Materials, Dr. Markus Feucht - HPC X271

  The local mechanical properties e.g. flow stress and fracture strain in an automotive component manufactured by deep drawing are inhomogeneous due to different local deformation degrees which affect the component behaviour under crash loading. A reasonable approach for modelling the damage behaviour of a component produced by deep drawing is a coupling between forming simulation and crash simulation. The open questions are which material model (kinematic or isotropic hardening) and which damage model should be used for an integrated simulation. Since the loading type is mainly biaxial at deep drawing and uniaxial under crash, it should be investigated how the damage development is influenced by deformation history including change of stress state. In this work the influence of triaxiality and pre-deformation on damage behaviour of a TRIP steel was characterized with different specimen tests e.g. under shear, uniaxial and biaxial tension and a damage model taking into account shear fracture and dimple rupture was developed. This damage model can also describe the influence of pre-deformation. Validation tests on an automobile component under a loading close to reality were performed and simulated with pre-strains and pre- damage mapped from a forming model to the crash model.

• Damage modelling of a TRIP steel for integrated simulation from deep drawing to crash

  Dr. Dong-Zhi Sun, Dr. Florence Andrieux - Fraunhofer Institute for Mechanics of Materials, Dr. Markus Feucht - HPC X271

  The local mechanical properties e.g. flow stress and fracture strain in an automotive component manufactured by deep drawing are inhomogeneous due to different local deformation degrees which affect the component behaviour under crash loading. A reasonable approach for modelling the damage behaviour of a component produced by deep drawing is a coupling between forming simulation and crash simulation. The open questions are which material model (kinematic or isotropic hardening) and which damage model should be used for an integrated simulation. Since the loading type is mainly biaxial at deep drawing and uniaxial under crash, it should be investigated how the damage development is influenced by deformation history including change of stress state. In this work the influence of triaxiality and pre-deformation on damage behaviour of a TRIP steel was characterized with different specimen tests e.g. under shear, uniaxial and biaxial tension and a damage model taking into account shear fracture and dimple rupture was developed. This damage model can also describe the influence of pre-deformation. Validation tests on an automobile component under a loading close to reality were performed and simulated with pre-strains and pre- damage mapped from a forming model to the crash model.

• Damping Modeling in Woven Lattice Materials

  S. Szyniszewski (University of Surrey), S. Ryan, S. Ha, Y. Zhang, T. Weihs, K. Hemker, J.K. Guest (The Johns Hopkins University Baltimore)

  Woven lattice materials were modelled to develop thin sheet dampers for attenuation of vibrations in high temperature environments. 3-D weaving has enabled manufacturing of woven lattice materials from metallic fibers that are suitable for high temperature applications. Such materials offer promising dynamic characteristic such as high vibration damping that can be combined with cooling and adequate stiffness. Dynamic tests of NiCr woven samples were simulated using LS-DYNA software in order to examine the energy dissipation mechanisms.

• Data Management and Loadcase Composition in ANSA

  T. Fokilidis, L. Rorris, T. Loiras (BETA CAE)

  It is common knowledge that simulations of virtual models hold a key role during the design process of a vehicle. Considering the continuously growing number of regulations, but also the different variants that a vehicle can have, one concludes to a plethora of similar or completely different simulations. As far as a simulation process is concerned one of the most demanding issues is its build up. The tools that a CAE analyst should have at ones disposal must be characterized by robustness and automation to deal with the numerous and really complex numerical simulations. The most important case during the model build up is a comprehensive model organization. BETA CAE Systems has come up with new data types that facilitate the set-up for the LS-DYNA simulation run. These new data types come to fully support data management in both, ANSA and LS-DYNA Include, files but furthermore in SPDRM implementations. Moreover, advanced capabilities of version control and the storage of all attributes that a file needs to be followed during a simulation build up, ensure a productive process starting from file input, moving to the assembly, passing to the load-case set up and finalizing with a bulk LS-DYNA file output. The current paper introduces the new ANSA techniques for a successful LS-DYNA simulation run set up that decreases the production time to its minimum and avoids errors that human interaction produces inevitably.

• Data preparation for the Euro NCAP far-side ISO/TS 18571 rating calculation with tools from the DYNAmore Eco System

  Alexander Schif, Venkata Krishna, Yupeng Huang, Sebastian Stahlschmidt

  In 2024 the Euro NCAP Virtual Testing far-side protocol was introduced with a monitoring phase. The protocol defines all the requirements in precise detail. To obtain an assessment for the virtual testing, the OEM needs to pass two validation load cases. The assessment is conducted using ISO/TS 18571 ratings. Euro NCAP is responsible for the ISO/TS 18571 rating calculations. The OEM must provide the simulation and test data in a predefined ISO MME data format. If the ratings meet the defined criterion, the virtual testing assessment is deemed successful. This paper presents a straightforward workflow for preparing ISO MME data, illustrated by a case study of a far-side test involving the open-source Toyota Yaris car and the DYNAmore WorldSID 50th dummy model in LS-DYNA. The DYNAmore Eco System tool DM.binout2isomme is used to create the required ISO MME files for sharing with Euro NCAP. Furthermore, the ISO/TS 18571 scores are calculated with a Python script with the same procedure as defined by Euro NCAP.

• DDAM Analysis with LS-DYNA

  Y. Huang, Z. Cui (LSTC)

  DDAM (Dynamic Design Analysis Method) is a U.S. Navy-developed analytical procedure for shock design. It helps validate the design of onboard equipment and structures subject to dynamic loading caused by underwater explosions (UNDEX). It is a widely accepted procedure for safety evaluation for civil and military ship building. The keyword for response spectrum analysis (*FREQUENCY_DOMAIN_RESPONSE_SPECTRUM) in LS-DYNA has been extended to run DDAM analysis for shipboard components, with the option _DDAM. This paper first gives a brief review of the theory for DDAM analysis. Then, with several examples, this paper shows how to run DDAM analysis with LS-DYNA and how to perform post-processing of the results. For purpose of cross-validation, the results of DDAM analysis with LS-DYNA in the first example are compared with that given by other commercial code.

• Deep drawing simulation of α-titanium alloys using LS-Dyna

  Sebastijan Jurendić - University of Ljubljana, Silvia Gaiani - University of Modena and Reggio Emilia

  Titanium alloys have excellent properties for their target applications; however their use is still limited by high price and formability issues. To avoid extensive on-site trials and to cut development costs, a numerical simulation method is developed for the deep drawing process of α-titanium (hexagonal close packed) alloy sheet using LS-Dyna. The Barlat 1989 material model is adopted for modelling the plastic response of the material and the necessary input data is examined. It is found that in order to adequately capture the plastic properties of HCP titanium, load curves are needed both for strain hardening and to capture the strain dependency of the plastic strain ratio. A procedure for determining the material input data from the tensile test results is developed and an exemplary data set is given. To identify a suitable value of the Barlat flow potential exponent m a parametric analysis is carried out using a simulation of the Erichsen cupping test. Forming limit diagrams are adopted for failure prediction, the forming limit curves are determined using the Nakajima method and a simplified procedure for obtaining limiting shear strains on a tensile testing machine is presented. To confirm the method an example of a deep drawn end-cap for a motorcycle exhaust muffler is presented and the simulation compared to the physical forming process with good results.

• Define_Pressure_Tube: Simulating Pressure Tube Sensors in Pedestrian Crash

  J. Karlsson (DYNAmore Nordic)

  This paper presents the new keyword *DEFINE_PRESSURE_TUBE, designed to efficiently simulate pressure waves in a thin air-filled tube. The main application in mind is a crash detection system for pedestrian safety, where an air-filled tube is embedded in the front bumper and fitted with pressure sensors at the ends. In the case of an impact, the tube is compressed and a pressure wave travels to the sensors, enabling localization and extent of the impact. In recent years, such systems have gained popularity in the automotive industry, posing a challenging task in efficient and accurate simulations. The keyword defines a closed gas filled tube using (hollow) beam elements and the pressure is calculated from area changes, given by contact penetration from surrounding elements. Pressure propagation is governed by a 1D model based on the compressible Euler equations, resulting in a very efficient method compared to 3D CFD or particle methods. Pressure, density, velocity and tube area are output through the keyword *DATABASE_PRTUBE, and can be visualized in LS-PREPOST. The aim of this paper is to give an overview of the theory and usage of the keyword, as well as show comparisons with experiments and existing methods in LS-DYNA.

• Definition of Peak Virtual Power Brain Trauma Variables for the use in the JSOL THUMS injury post-processor web-based estimator

  C. Bastien (Coventry University), C. Neal-Sturgess (University of Birmingham), H. Davies, X. Cheng (Coventry University)

  Road traffic accidents and falls are catastrophic events leading to serious injury and in some cases fatality. The dichotomy is that traumatic injuries are assessed using the Abbreviated Injury Scale (AIS), which is a measurement of the probability of death, whilst the engineering tools available to support the understanding of injury causation rely on engineering measurements of stress and strain. Further to this, the problem of ageing is not adequately dealt with using existing engineering tools. The research proposes the development of a generic mathematical injury severity model, based on Peak Virtual Power (PVP) [1], to establish relationships between AIS, ageing and collision speed. This method, newly implemented JSOL THUMS injury post-processor web-based estimator, has the ability to calculate all AIS levels from the white and grey matter and is defined as a polynomial function. This paper explains the underpinning of the Peak Virtual Power theory, as well as provide the coefficients to calculate brain injury severity under blunt trauma impact.

• Deformable Rigid Bodies in LS-DYNA with Applications – Merits and Limits

  Karl Schweizerhof, Johann Bitzenbauer - University Karlsruhe, Germany, Ulrich Franz - DYNAmore GmbH, Germany

  Modal methods are long known in linear dynamic analysis for efficient computations of the response of structures. The mechanical idea behind is to find a particularly useful problem dependent basis (so called eigenfunctions or eigenmodes) which can be separated into some of major importance for the behavior of the structure and others of minor interest (which can be subsequently disregarded). Unfortunately this concept is basically a completely linear one. However, more recent versions of LS-DYNA offer the possibility to superimpose shape functions from a previously computed eigenmode basis with a nonlinear rigid body motion for parts of the structure. This allows to consider at least some of the elastic behavior of a body which would be otherwise considered completely rigid. The resulting displacements are then computed with standard explicit methods, allowing on one side a substantial reduction of the number of degrees of freedom and on the other side parts of the system can be still computed in a fully nonlinear manner. The method has been presented in [1]. In the current contribution, two different practical applications, a head impact problem and a deep drawing simulation are presented and compared to a fully nonlinear solution.

• Deformation Behaviour of Filled and Capped PET Bottles in the High-Speed Labeling Machine

  Bharat Chittepu, Matthias Hörmann, Ulrich Stelzmann - CADFEM GmbH, Harald Wels, Thomas Albrecht - KRONES AG

  The increasing use of PET bottles has been and continues to be a dramatic growth story in the packaging industry. The adaption of PET bottles for soft drinks, juice drinks, water, food and other products continues to provide exciting packaging opportunities. Increasing use meant increase in demand and the need for saving time in the process chain of the packaging industry. One area where a high speed process is possible is labeling. In higher output ranges in the labeling technology, PET bottles are subjected to undesirable deformations which in turn might result in bottle losses in the machine carrousel or to a bad placement of the label. Information on this deformation should be available in the earliest possible stage of machine planning, such that the desire to simulate comes into play. Before simulating such a high speed labeling process, it is necessary to have a reliable filled PET bottle model which is justified to be used in the simulation of the real process. The first step in this approach is to simulate the top load performance of an empty PET bottle and validate the simulation results with experimental results by comparing load and buckling deformation. Sensitivity studies are carried out with respect to material, geometry and Finite Element parameters to obtain an optimized parameter set which ensures a reliable model of the empty PET bottle. This model is then the basis to simulate the top load performance of liquid filled PET bottle. For the filled PET bottle the right modeling approach to account for the presence of liquid, i.e. water and its associated physics (inertia, compressibility and hydrostatic pressure), must be determined. Control Volume, Smoothed Particle Hydrodynamics and Arbitrary Lagrangian Eulerian approaches are discussed to highlight the benefits and drawbacks of each approach for accurately simulating the top load performance of filled PET bottle. Load-deformation curves and bucking shapes of the top load test are compared with simulation results to justify the usage of a reliable filled PET bottle. The third and final step is to simulate the high speed labeling process by identifying the right approach to account for the machine kinematics and the inertia effects of the liquid. Added element mass or SPH approach for accounting inertia of the liquid in combination with machine kinematics is investigated in order to identify the most accurate combination for bottle deformation in the labeling process.

• Deformation Behaviour of Filled and Capped PET Bottles in the High-Speed Labeling Machine

  Bharat Chittepu, Matthias Hörmann, Ulrich Stelzmann - CADFEM GmbH, Harald Wels, Thomas Albrecht - KRONES AG

  The increasing use of PET bottles has been and continues to be a dramatic growth story in the packaging industry. The adaption of PET bottles for soft drinks, juice drinks, water, food and other products continues to provide exciting packaging opportunities. Increasing use meant increase in demand and the need for saving time in the process chain of the packaging industry. One area where a high speed process is possible is labeling. In higher output ranges in the labeling technology, PET bottles are subjected to undesirable deformations which in turn might result in bottle losses in the machine carrousel or to a bad placement of the label. Information on this deformation should be available in the earliest possible stage of machine planning, such that the desire to simulate comes into play. Before simulating such a high speed labeling process, it is necessary to have a reliable filled PET bottle model which is justified to be used in the simulation of the real process. The first step in this approach is to simulate the top load performance of an empty PET bottle and validate the simulation results with experimental results by comparing load and buckling deformation. Sensitivity studies are carried out with respect to material, geometry and Finite Element parameters to obtain an optimized parameter set which ensures a reliable model of the empty PET bottle. This model is then the basis to simulate the top load performance of liquid filled PET bottle. For the filled PET bottle the right modeling approach to account for the presence of liquid, i.e. water and its associated physics (inertia, compressibility and hydrostatic pressure), must be determined. Control Volume, Smoothed Particle Hydrodynamics and Arbitrary Lagrangian Eulerian approaches are discussed to highlight the benefits and drawbacks of each approach for accurately simulating the top load performance of filled PET bottle. Load-deformation curves and bucking shapes of the top load test are compared with simulation results to justify the usage of a reliable filled PET bottle. The third and final step is to simulate the high speed labeling process by identifying the right approach to account for the machine kinematics and the inertia effects of the liquid. Added element mass or SPH approach for accounting inertia of the liquid in combination with machine kinematics is investigated in order to identify the most accurate combination for bottle deformation in the labeling process.

• Delamination and Fracture Modeling Techniques for Shell Composite Structures in LS-DYNA®

  A. Polla, E. Cestino, G. Frulla, P. Piana (Politecnico di Torino)

  Define numerical analysis capable of predicting the behaviors of laminates composites is a research challenge for engineers and scientists from the first implementation of laminated model for shell elements in 1984 [1]. In these last 35 years all aspects of composite materials behavior have been evaluated such as for example, the impact response, crack propagation, crushing resistance. All contributions, for example from Abrate [2], Farley et al. [3], Botkin et al. [4] to actuals individuated a lot of ways to study numerically all aspects associated to related topic, as descripted and clearly resumed in the following picture.

• Delamination Prediction and Non-local Averaging using a Composite Micro-Mechanical Model

  Ala Tabiei, Sandeep Medikonda, Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA

  Inter-laminar delamination in laminated composites has been studied with the help of thickness-stretch shell elements using a 3-D material model and compared against the traditional plane-stress shell elements. A strain-rate and pressure dependent micro-mechanical material model using ply-level progressive failure criteria has been used to simulate the initiation and propagation of delamination. The material parameters of the non-linear resin have been determined using LS-OPT®. The numerical delamination growth has been qualitatively analyzed against the experimental C-scan images for multiple impact events on different composite plates. In addition, a non-local model with an isotropic weight function has been implemented to work in conjunction with the composite micro-mechanical material model to alleviate strain softening typically seen in composite materials.

• Delamination Prediction of Uni-Directional Composite Laminates using Shell Elements and a Strain Rate Dependent Micro-mechanical Material Model

  Sandeep Medikonda, Ala Tabiei (University of Cincinnati, Cincinnati)

  The effectiveness of studying inter-laminar delamination in composites with the help of newly formulated thickness-stretch shell elements (ELFORM=25) as compared to the traditional plane-stress shell elements (ELFORM=2) has been investigated using LS-DYNA ® . A strain-rate dependent micro-mechanical material model using ply-level progressive failure criteria has been used to simulate the initiation and propagation of delamination. The numerical delamination growth has been qualitatively analyzed against the experimental C-scan images for multiple impact events on a T800H/3900-2 CFRP plate. As an addition to the capability of the micro-mechanical material model, a methodology of assigning physical significance to the choice of damage parameters has been presented.

• Demand Driven Side Impact Restraint System Development Method

  Gary Owen - Autoliv

  This paper describes a demand driven product development method that applies a synergetic combination of numerical simulation and physical test techniques to guide the development of side impact restraint systems and associated simulation procedures and physical test devices.

• Demonstrating LS-DYNA®’s Capabilities in Welding Simulations by Experiments

  Maarten Rikken, Gianmarco Montalbini, Bruna Frydman, David Gration (ARUP)

  This study examines the welding residual stress formation in a bead-on-plate welded specimen using LS-DYNA and a series of physical experiments to validate the simulation approach. Calculating residual stresses numerically could be used to improve welding procedures or to assess the structural integrity of welded joints in service conditions. Dilatometer and tensile tests at elevated temperature were conducted to obtain thermal expansion behavior and stress-strain curves of the S355G10+M base material. The software package JMatPro provided the other material properties required for the welding simulations in LS-DYNA. A thermal analysis was set up in LS DYNA to simulate a bead-on-plate welded specimen for which the weld heat input was modelled with the Goldak heat flux distribution. Welding experiments were carried out and the transient temperature distribution during welding was measured with thermocouples. This was used to calibrate the thermal analysis in LS-DYNA. Macrographs of the welded specimen helped to validate the fusion zone shape and cooling rate in the heat affected zone. The thermal analysis results were subsequently coupled with a mechanical analysis to calculate the thermal strains and residual stress formation. *MAT_270/CWM was used for this analysis as it is able to reproduce the transient weld material deposition. The residual stress over the full depth of the specimen was compared to the experimentally obtained residual stress state. The crack compliance method was used to experimentally measure the residual stress over the full depth of the specimen. The numerically and experimentally determined residual stress distributions are in good agreement. This study demonstrates the capabilities of LS-DYNA to simulate welding procedures and validates the corresponding results using physical experiments.

• Deployment Simulations of Space Webs

  M. Gärdsback, G. Tibert - Royal Institute of Technology

• Desicion Making in Multi-Objective Optimization for Industrial Applications - Data Mining and Visualization of Pareto Data

  Katharina Witowski, Martin Liebscher - DYNAmore GmbH, Tushar Goel - Livermore Software Technology Coorporation

  Optimization of engineering structures where multiple (more or less conflicting) objectives are simulta- neously considered, is getting more and more attractive in automotive industries. They usually involve a large number of design variables and the objectives are subject to certain constraints. Unlike single- objective problems, there are many trade-off solutions. The most common approach of using a single aggregate objective function (AOF), though simple, is not appropriate in most cases because a) it requires a priori information e.g., weights associated with each objective for weighted linear sum of the objectives method, that might not be available; and b) this approach yields a single trade-off solution instead of all possible trade-off solutions. Multi-objective evolutionary algorithms (MOEA) seem to be the best choice at the moment to overcome these issues. A set of solutions (Pareto data) is obtained as result, which reflect distinct trade-off so- lutions. A (optimal) decision needs to be taken to choose the most suitable trade-off among multiple conflicting objectives. Data mining and visualization techniques for high dimensional data provide helpful information to sub- stantially augment the decision making (alternative design selection) in multi-objective optimization en- vironment. A graphical approach to visualize the Pareto frontier is an intuitive and suitable approach to investigate the trade-off for three or fewer dimensions (objectives). However, it is not trivial to study relations in higher dimensions hence many visualization methods are proposed. The basic idea of these techniques is to reduce the dimensionality without loosing the relevant information required to recognize and understand relations and characteristics of the high dimensional Pareto data. Among the several developments in these fields, the Parallel Coordinates Plot (PCP), the Hyper-Radial Visualization (HRV), and the Self Organizing Maps (SOM) have been found the most promising. The parallel coordinates plot assigns one axis to each dimension and many dimensions are aligned in parallel. A data point is represented as a line connecting different axes. The HRV is based on a ra- dial calculation and transfers the multi-dimensional data to a two-dimensional data set by grouping the weighted objectives, that leads to a final solution with respect to the selected weights and the grouping. The designer incorporates his preferences by modifying the selection. The SOM algorithm projects the multi-dimensional Pareto data onto a two-dimensional map, whereby similar data is mapped to neigh- boring locations on the map. The lattices are color-coded to show the variation of the data on the map. The concepts of PCP, HRV and SOM are explained along with the various forms of visualization of Pareto data. All three approaches are investigated and respective pros and cons are identified using a shape optimization case crash application executed with LS-OPT. An implementation in the data mining and visualization framework D-SPEX is also provided.

• Desicion Making in Multi-Objective Optimization for Industrial Applications - Data Mining and Visualization of Pareto Data

  Katharina Witowski, Martin Liebscher - DYNAmore GmbH, Tushar Goel - Livermore Software Technology Coorporation

  Optimization of engineering structures where multiple (more or less conflicting) objectives are simulta- neously considered, is getting more and more attractive in automotive industries. They usually involve a large number of design variables and the objectives are subject to certain constraints. Unlike single- objective problems, there are many trade-off solutions. The most common approach of using a single aggregate objective function (AOF), though simple, is not appropriate in most cases because a) it requires a priori information e.g., weights associated with each objective for weighted linear sum of the objectives method, that might not be available; and b) this approach yields a single trade-off solution instead of all possible trade-off solutions. Multi-objective evolutionary algorithms (MOEA) seem to be the best choice at the moment to overcome these issues. A set of solutions (Pareto data) is obtained as result, which reflect distinct trade-off so- lutions. A (optimal) decision needs to be taken to choose the most suitable trade-off among multiple conflicting objectives. Data mining and visualization techniques for high dimensional data provide helpful information to sub- stantially augment the decision making (alternative design selection) in multi-objective optimization en- vironment. A graphical approach to visualize the Pareto frontier is an intuitive and suitable approach to investigate the trade-off for three or fewer dimensions (objectives). However, it is not trivial to study relations in higher dimensions hence many visualization methods are proposed. The basic idea of these techniques is to reduce the dimensionality without loosing the relevant information required to recognize and understand relations and characteristics of the high dimensional Pareto data. Among the several developments in these fields, the Parallel Coordinates Plot (PCP), the Hyper-Radial Visualization (HRV), and the Self Organizing Maps (SOM) have been found the most promising. The parallel coordinates plot assigns one axis to each dimension and many dimensions are aligned in parallel. A data point is represented as a line connecting different axes. The HRV is based on a ra- dial calculation and transfers the multi-dimensional data to a two-dimensional data set by grouping the weighted objectives, that leads to a final solution with respect to the selected weights and the grouping. The designer incorporates his preferences by modifying the selection. The SOM algorithm projects the multi-dimensional Pareto data onto a two-dimensional map, whereby similar data is mapped to neigh- boring locations on the map. The lattices are color-coded to show the variation of the data on the map. The concepts of PCP, HRV and SOM are explained along with the various forms of visualization of Pareto data. All three approaches are investigated and respective pros and cons are identified using a shape optimization case crash application executed with LS-OPT. An implementation in the data mining and visualization framework D-SPEX is also provided.

• Design and Implementation of a Multi-Fabric Message Passing Interface (MPI): Intel® MPI Library

  Dr. Michael D'Mello - Intel Americas Inc., USA

  Environment & Situation Analysis Program direction Intel® MPI Design Considerations – High Level Design – Stability – Functionality – Performance – Portability – Environment & Tools support – Extensibility Highlights of Intel® MPI Program

• Design and Material Characterization of Reinforced Plastics for Secondary Structural Load Paths in an Early Development Phase

  D. Moncayo (Daimler), M. Cyperling (Mercedes-Benz Werk), G. Dumitru, T. Graf (DYNAmore), D. Coutellier, H. Naceur (Université Polytechnique Hauts-de-France)

  This paper presents different modeling approaches and technical challenges for the discretization of anisotropic elastic-viscoplastic materials in secondary structural parts for the automotive sector. In terms of accuracy, complex geometries based on reinforced plastics in secondary load paths need to factor in the manufacturing process and the resultant local anisotropies within correspondent CAE models. However, during the early phase of product development, integrating reinforced plastics, a robust numerical basis throughout the concept evaluation is required. The basic idea is to maintain the correspondent level of complexity through the subcomponent design within certain limits, in order to improve, speed up and adequately handle complexity in CAE concepts for the automotive sector. Finally, a benchmark analysis of possible options and modeling techniques is introduced, as a contribution to evaluate the balance between the dimensioning of structural load paths and the required material characterization within an acceptable effort.

• Design and Testing of an Easy to Use Pinned-down Temporary Concrete Barrier with Limited Deflections

  N. M. Sheikh, R. P. Bligh (Texas Transportation Institute)

  In work zones where the space available for placing a temporary concrete barrier is very limited, for example bridge replacement projects, the barrier must be strictly restrained to prevent lateral deflection due to vehicular impact. Among the few restraining or anchoring mechanisms currently available, most designs require through the deck bolting, anchor bolts, or other constraining straps. Such mechanisms are difficult to install, inspect, and remove and can result in damage to thin bridge decks. In this research, a new restrained F-shaped temporary concrete barrier was developed that is easy to install, inspect, and remove, and minimizes damage to the bridge deck or concrete pavements. The mechanism uses a pinned-down approach to restrain the barrier. Steel pins are simply dropped into inclined holes that start from the toe of the barrier and continue short distance into the bridge deck or concrete pavement. The pinned down anchorage design was developed through extensive use finite element analysis. The performance of the final design was evaluated by conducting a full-scale vehicle impact crash test. The pinned down barrier successfully passed the National Cooperative Research Program Report 350 Test Level 3 requirements. The maximum permanent and dynamic barrier deflections were 5.76 inches (146.3 mm) and 11.52 inches (292.6 mm), respectively.

• Design and Validation of a Crash Rated Bollard as per SD-STD-02.01 Rev. A (2003) Standard using LS-DYNA ®

  Saurabh R. Deshpande, Santosh E. Chopade, N. V. Karanth (Automotive Research Association of India), Maj. Amitava Mittra (Swaraj Secutech Pvt. Ltd.)

  Use of vehicle barriers for traffic regulation is of utmost importance in a densely populated country like India. These barriers can be used effectively to divert vehicles during public events and emergency situations. Due to their periodic requirement at different locations, it is essential that the barriers provide visibility and security while remaining comparatively cheaper at the same time. Out of the different types of available barriers like solid walls, pillars, beams, gates, etc., a bollard (vertical pole protruding from the ground to a very less but visible height) is the most effective in terms of space occupied and absorption of impact energy. Multiple bollards used in series are effective towards withstanding large vehicle impacts, while allowing passage to pedestrians and bicycle riders with ease. The prevalent methodology of evaluating energy absorption capacity of bollard as per SD-STD-02.01 Rev. A (2003) standard includes physical impact of the designed bollard by designated vehicle type (M type of vehicles) for K-4, K-8 and K-12 types of crash ratings. A finite element (FE) model of the designed bollard was analyzed under similar impact conditions using crash analysis software (LS-DYNA v. 971). The FE results were validated with the results of the physical test conducted subsequently. Parametric optimization of the K-12 rated FE bollard was conducted and a new bollard design for K-8 rating was thus prepared and analyzed for vehicular impact. The use of Computer Aided Engineering (CAE) tools and FE analysis during design stage itself aimed at reducing the cost and time required to build and successfully test the bollard for crash rating.

• Design Domain Dependent Preferences for Multi-disciplinary Body-in-White Concept Optimization

  Nikola Aulig,Honda Research Institute Europe GmbH, Offenbach/Main, Germany;, Satchit Ramnath, Emily Nutwell, The Ohio State University SIMCenter, Columbus, OH, USA;, Kurtis Horner, Honda R&D Americas, Inc., Raymond, OH, USA

  Recently methods for topology optimization are increasingly established in the virtual vehicle design process in the automobile industry. In particular a heuristic topology optimization process based on the assumption of uniform energy distribution throughout the structure combined with a scaled energy weighting approach was demonstrated to successfully to provide concepts for vehicle structures subject to static and crash loads concurrently. However, topology optimization for problems with multiple load cases is conventionally based on the assumption of all loads requirements being relevant throughout the complete design domain. This neglects potential design targets such as the restriction of certain load paths to specialized subdomains. For instance, typically, the energy absorption of a front crash of a vehicle is expected to be limited to components in the front of the vehicle. In this work we propose to address this issue for topology optimization of LS-DYNA® models subject to multiple load cases by subdomains with design domain dependent preferences. This enables a specialization of subdomains to the designer’s requirements. We show systematic evaluation results on a cantilever optimization problem and a possible application to the vehicle concept design.

• Design optimisation of a side impact beam made out of high strength aluminium alloys using Barlat YLD2000 and GISSMO failure model for the “Extended Hotforming Process”

  J. M. Schlosser, S. Mouchtar, W. Rimkus, R. Schneider (Hochschule Aalen)

  The automotive industry is facing new challenges due to stricter CO2 emission laws. Thus, to design more environmentally-friendly cars, various lightweight construction strategies need to be considered to meet the growing demand for resource efficiency [1]. In order to minimise weight, the lightweight design strategy "design for lightweight construction" is increasingly becoming important for industry. Especially the “structural optimisation” with its sub-areas: topology-, fibre-, thickness- and parameter-optimisation is designated as a very powerful tool for lightweight applications. In addition, damage and failure modelling is getting more and more important in order to predict the behaviour of any component by FEM-simulations as accurate as possible. For this purpose, the entire material history (from production right through to the crash of the component) must be taken into account. Whereas for forming processes forming limit curves (FLC`s) are sufficient to predict the material behaviour failure models, which describe failure as a function of stress states, need to be applied for detailed crash calculations [2]. In this paper the design process of an AA7075 side impact beam will be presented; starting from structural optimisation through to the calibration of a material and a damage model. The geometry of the side impact beam is determined by topology optimisation. Special attention is given towards the temperature control of the forming process since a “Thermal Direct Joining” procedure (e.g. for CFRP-patches) is aimed to be implemented. The high-strength anisotropic aluminium alloy (AA7075) is characterised after applying the Hotforming process (Hotforming condition). Both, the Barlat YLD2000 material model and the GISSMO failure model are calibrated using the graphical optimisation tool LS-OPT.

• Design Optimization of the Beagle II Mars Lander Airbags Through Explicit Finite Element Analysis – An Update

  Anthony P. Taylor - Irvin Aerospace Inc

  The Beagle II Mars Lander is a portion of the European Space Agency (ESA) Mars Express program. Irvin Aerospace Limited, on contract to Martin Baker Aerospace Ltd., will provide the parachutes and airbags for the probe’s landing system. The purpose of the Beagle II Lander is to deliver scientific equipment, which will perform atmospheric and soil experiments focused on identifying signs of life on the Red Planet. To reduce development costs, the parachute system will be identical to the Huygens probe parachute, which is currently enroute to the Saturn moon Titan. This parachute has been the subject of previous papers. The parachute system, lander mass, and landing atmospheric conditions therefore define the conditions for the airbag first impact. This paper presents the results of concept development analysis for the Beagle II mission. Airbag design requirements, including the somewhat challenging impact velocity of 30.0 m/sec are presented. Several design iterations explored using the Explicit Finite Element Analysis (FEA) code LS-DYNA are presented.

• Design optimization with Modal Assurance Criteria (MAC)

  Sumie Kinouchi, Ryo Ishii, Masahiro Okamura (JSOL Corporation)

  Simulation-based optimization is one of the efficient tools for product design optimization. This paper introduces the application example of modal analysis with LS-DYNA® and mode tracking of LS-OPT ®, to improve the body stiffness. The mode tracking is a powerful tool to track a specific mode by evaluating the scalar MAC value even if the sequence of modes is changed due to the modification of the design variables by the optimizer. For the connection in the car body model, adhesive bonding is included as well as spot welding.

• Design Qualification of the Jupiter Icy Moons Explorer JENI Instrument using the LS-DYNA Frequency Domain Suite

  M. Shanaman, S. Cooper, S. Jaskulek, C. Schlemm, P. Brandt, D. Mitchell, E. Rollend (Johns Hopkins University)

  In 2022 the European Space Agency (ESA) will launch the JUpiter ICy moons Explorer (JUICE) for an 11-year mission to the Jovian system. The Particle Environment Package (PEP) suite of sensors includes the Jovian Energetic Neutrals and Ions sensor (JENI), designed, built, and qualified by The Johns Hopkins University Applied Physics Laboratory. The requirements established to ensure JENI withstands the launch environment include a first instrument mode above 140 Hz and positive structural margin when subjected to 39g per axis quasi-static analyses and random vibration analyses totaling up to 9.12 grms.

• Designing a Radioactive Material Storage Cask Against Airplane Crashes With LS-DYNA®

  Gilles Marchaud, Louis Vilela, Stéphane Nallet (AREVA TN)

  For 50 years, AREVA TN has been supplying customer-focused, innovative transportation and storage solutions for radioactive material with the highest levels of safety and security. Transportation and storage casks are designed to comply with stringent regulations. For instance, the TN NOVA™ system, designed to store used fuel assemblies, is required to withstand the impact of a 20-ton aircraft at a velocity of 215m/s, despite the extremely small probability of such an event actually occurring. The TN NOVA™ system is composed of a sealed NUHOMS®-69BTH Dry Shielded Canister and a TN NOVA™ Overpack. The overpack has been designed to house the canister during the storage period and provide it with an efficient protection against airplane crash events. To achieve this, LS-DYNA® was invaluable in helping us to improve the preliminary design and to select the most damaging airplane impact configuration. LS-DYNA® analyses also made it possible to design an equivalent missile that causes deformations at least equal to those caused by an airplane crash. The equivalent missile model was updated thanks to a real test onto a concrete wall. Finally, the overpack design was successfully validated by a real test. The equivalent missile impacted a 1/3 scale mock-up of the canister-loaded overpack, fitted with strain gages and accelerometers. Leak tightness was preserved. The present paper will focus on the crashworthiness LS-DYNA® calculations and benchmarks that made this success possible.

• Designing Shock Absorbers for Nuclear Transport Packages

  A Sean Duvall

  Across the world, radioactive sources are used for a variety of applications. From X-rays and radiotherapy in hospitals, to generation of heat in a nuclear power station. All these sources, however small or large, need to be transported to the point of use and away from there for eventual disposal or recycling. It is more often the case that when the sources are transported to the site, before use, they are not particularly radioactive, but after use they can pose a serious health hazard if not handled correctly. Special, specifically designed transport packages are manufactured and tested to ensure they meet the regulatory requirements for the transport of radioactive materials [1]. Part of the regulatory requirements is that the package withstands a 9m drop on to an unyielding target without loss of containment. The external shock absorbers of a transport package are designed to absorb the energy from this impact, as well as provide other functions not covered in this paper. This paper looks at methods to assist in the designing of these shock absorbers and how LSDYNA can be instrumental in the design and testing phase.

• Detail Design Evaluation of Extruded Sections on a Body-in-White Concept Model

  Satchit Ramnath, Emily Nutwell, SIMCenter, The Ohio State University, Columbus, OH, USA;, Nikola Aulig, Honda Research Institute Europe GmbH, Offenbach/Main, Germany;, Kurtis Horner, Honda R&D Americas Inc., Raymond, OH, USA

  Topology optimization allows for the design of structures with an optimum distribution of material for a given set of load cases. In the past, it has been shown that topology optimization can be implemented for a design space representing a body-in-white vehicle structure undergoing multiple load requirements. Using a Hybrid Cellular Automata algorithm along with a scaled energy weighting approach, both the objective of maximizing stiffness as well as maximizing compliance can be considered concurrently for multiple load cases. This methodology using LS-TaSC™ generates the optimum load paths for the design space subjected to the defined load cases. However, designers are often interested in applying local manufacturing constraints, such as extrusion constraints, on specific portions of the larger design space.

• Determination of Flow Curves by Stack Compression Tests and Inverse Analysis for the Simulation of Hot Forming

  B. Hochholdinger, P. Hora - ETH Zurich, H. Grass, A. Lipp - BMW AG

  Due to the increasing number of body-in-white parts that are manufactured by hot forming of boron alloyed sheet metal (22MnB5), the demand for a virtual representation of this specific manufac- turing process is evident. For a realistic simulation of hot stamping processes, the accurate modeling of the flow stress as function of strain, strain rate and temperature is essential. In the last years a large varity of empirical-analytical as well as physically based models for the yield stress has been proposed. Three existing models that have shown a good capability to represent the flow behavior of 22MnB5 in recent publications are presented and fitted to the experimental data. The underlying experimental data for the determination of the flow stress is obtained by stack compression tests, which were conducted in a high-speed deformation dilatometer. In a first step the model parameters are fitted to the experimental flow curves without considering the friction, which inherently is present in a compression test. Since the friction between die and specimen has significant influence on the state of stress within the specimen, an inverse, simulation-based ap- proach for the determination of the model parameters is employed. For this purpose a simple 2D FE model for each test configuration is set up. The resulting “friction-free” yield stress is up to 15% lower than the one without considering friction. Regarding the models considered, the approach developed by TONG and WAHLEN, which is based on the Z ENER -H OLLOMON parameter and a H OCKETT-S HERBY type formulation, provides the best fit of the experimental data.

• Determination of Flow Curves by Stack Compression Tests and Inverse Analysis for the Simulation of Hot Forming

  B. Hochholdinger, P. Hora - ETH Zurich, H. Grass, A. Lipp - BMW AG

  Due to the increasing number of body-in-white parts that are manufactured by hot forming of boron alloyed sheet metal (22MnB5), the demand for a virtual representation of this specific manufac- turing process is evident. For a realistic simulation of hot stamping processes, the accurate modeling of the flow stress as function of strain, strain rate and temperature is essential. In the last years a large varity of empirical-analytical as well as physically based models for the yield stress has been proposed. Three existing models that have shown a good capability to represent the flow behavior of 22MnB5 in recent publications are presented and fitted to the experimental data. The underlying experimental data for the determination of the flow stress is obtained by stack compression tests, which were conducted in a high-speed deformation dilatometer. In a first step the model parameters are fitted to the experimental flow curves without considering the friction, which inherently is present in a compression test. Since the friction between die and specimen has significant influence on the state of stress within the specimen, an inverse, simulation-based ap- proach for the determination of the model parameters is employed. For this purpose a simple 2D FE model for each test configuration is set up. The resulting “friction-free” yield stress is up to 15% lower than the one without considering friction. Regarding the models considered, the approach developed by TONG and WAHLEN, which is based on the Z ENER -H OLLOMON parameter and a H OCKETT-S HERBY type formulation, provides the best fit of the experimental data.

• Determination of Impact Loads for a Tracked Military Vehicle during a Crash Scenario

  B. Balaban (FNSS Savunma Sistemleri)

  In this study, crash simulation for a tracked military vehicle is performed and equivalent static and dynamic design loads are determined for a subsystem using LS-DYNA® and LS-OPT®. Detailed finite element model of the track geometry, suspension system and the hull is created. In order to have an accurate vehicle suspension behavior; some verification simulations are conducted with another commercial multibody software and the suspension kinematic is optimized. Full vehicle crash simulations are performed firstly and stress results are obtained from the sub-system mounts of the vehicle. Afterwards, small scale simulation model of the sub-system is created and LS-OPT® is used to get equivalent static and dynamic acceleration loads using the stress results which are obtained from crash simulation.

• Determination of Material Modeling Parameters using LS-OPT Based Optimization Technique

  Amritha U, Kottresh Kurudimath, Subhransu Mohapatra SABIC Research & Technology Center, Bangalore, India.

  Material models for high-performance thermoplastic polymers need to capture highly complex material characteristics accurately to enable lightweight and sustainable designs. ULTEMTM 1000 Polyetherimide Resin from SABIC’s Specialties business display different behavior under impact loading under multi-axial loading compared to uniaxial tensile testing.

• Determination of Optimal Cutting Conditions in Orthogonal Metal Cutting Using LS-DYNA with Design of Experiments Approach.

  David P. Masillamani, Jack Chessa - University of Texas at El Paso

  Optimal selections of cutting conditions contribute significantly to the increase in productivity and reduction in costs of machining processes. The main objective of the present paper is to explore the resultant temperature formed due to complicated interactions and between rake angle, depth of cut and cutting speed. Finite element simulations using LS-DYNA is used as a numerical experiment in the construction of a Design of Experiment (DOE) empirical model of orthogonal machining process. This DOE model is then used to study the temperature formation in the work piece with respect to parameters such as speed, depth of cut and rake angle. The results are also compared with experimental results which have been done already.

• Determining the Material Constants for Mullins Effect in Rubber Part One: Uniaxial

  William W. Feng, John O. Hallquist (LSTC)

  In this paper, the strain-energy density with Mullins damage function on unloading and subsequent reloading is considered. We introduce a damage function that has four material constants: two for unloading and two for subsequent reloading. The effect of these constants on unloading and subsequent reloading is studied for uniaxial extension. We determine these four material constants from a set of numerically generated uniaxial extension test data. The mathematical formulation has been implemented in LS-DYNA® for user application and evaluation. This paper will be extended to two-dimensional problems and a set of biaxial test data will be obtained and analyzed. The second part of this paper will be presented in another LS-DYNA conference.

• Determining the MPP LS-DYNA Communication and Computation Costs with the 3-Vehicle Collision Model and the Infiniband Interconnect

  Yih-Yih Lin - Hewlett-Packard Company

  The least square error approach applied to LS-DYNA communication and computation costs for the Neon model was shown previously by this author to be useful in predicting performance on a given interconnect of known ping- pong latency and bandwidth, and both Gigabit Ethernet and HyperFabric 2 results were presented. In this paper, this prediction method is applied to a much larger public-domain crash model, the 3-vehicle collision model, to determine communication and computation costs for models representative of the most demanding requirements. Furthermore, the result is verified against the new, high-speed low- latency Infiniband interconnect. Users of this method may perform trade-off analysis for optimum hardware configuration decisions without the need for extensive benchmark testing.

• Developing a Numerical Model for Human Brain under Blast Loading

  Atacan Yucesoy, Thomas J. Pence, Ricardo M. Alvarez, Michigan State University, East Lansing, MI 48824;, Adam M. Willis, Michigan State University, East Lansing, MI 48824, San Antonio Military Medical Center, Fort Sam Houston, TX 78234

  Blast-induced traumatic brain injury (bTBI) is one of the widespread causes of mortality and morbidity for military personnel. Exploring the mechanics of brain tissue is critical to predicting intracranial brain deformation and injury resulting from severe blast loading. This capability would help in obtaining a prognosis and choosing adequate neurosurgical procedures before a physical intervention takes place. In this conference paper, the aim is to build a numerical model using LS-DYNA® with the ability to capture the complex deformations induced by blast loading of the human brain. A coupling method of Load Blast Enhanced and Multi-Material Arbitrary Lagrange Eulerian are employed to generate the intracranial shock wave and to evaluate the interactions of brain layers, respectively. Relatively large displacement and velocity differences are observed between the skull and the gray matter. Complex interactions ensue when front-to-back moving coup waves meet back-to-front moving contrecoup waves. Shear stresses are highly localized at the interface of the gyri and cerebrospinal fluid and around the ventricles.

• Developing Failure Criteria for Application to Ship Structures Subjected To Explosive Blast Loadings

  Mark Tyler-Street, Joke Luyten - TNO Defence

  A research programme is being undertaken at TNO to investigate vulnerability reduction on warships. In this framework, studies have been performed regarding the structural damage due to both an internal missile explosion and close in explosions. Due to the severity of the explosive loadings the structural deformation is considerable and an accurate method to predict both the initiation and progression of material damage would be of significant value to assist in the design of more blast resistant structures. The ability to model material failure is available with many of the material models in the explicit finite element code LS-DYNA although further development is required in order to correlate to observed experimental results. In the material models, the initiation of failure is typically defined by the uni-axial failure strain ef. This parameter is not an independent material constant and the failure characteristics will vary depending upon the applied stress state (for example sensitivity to tri-axiality), the temperature and rate of loading. For ship plate steel the manufacturing process of rolling may introduce anisotropic failure characteristics which differ in the rolling and transverse directions. The failure strain needs to be adjusted for coarser meshes which are unable to represent local strain gradients. This paper describes some of the work that has been done to describe the failure properties of typical ship plate steel with the development of a user defined material model to predict and further understand the failure characteristics.

• Developing Failure Criteria for Application to Ship Structures Subjected To Explosive Blast Loadings

  Mark Tyler-Street, Joke Luyten - TNO Defence

  A research programme is being undertaken at TNO to investigate vulnerability reduction on warships. In this framework, studies have been performed regarding the structural damage due to both an internal missile explosion and close in explosions. Due to the severity of the explosive loadings the structural deformation is considerable and an accurate method to predict both the initiation and progression of material damage would be of significant value to assist in the design of more blast resistant structures. The ability to model material failure is available with many of the material models in the explicit finite element code LS-DYNA although further development is required in order to correlate to observed experimental results. In the material models, the initiation of failure is typically defined by the uni-axial failure strain ef. This parameter is not an independent material constant and the failure characteristics will vary depending upon the applied stress state (for example sensitivity to tri-axiality), the temperature and rate of loading. For ship plate steel the manufacturing process of rolling may introduce anisotropic failure characteristics which differ in the rolling and transverse directions. The failure strain needs to be adjusted for coarser meshes which are unable to represent local strain gradients. This paper describes some of the work that has been done to describe the failure properties of typical ship plate steel with the development of a user defined material model to predict and further understand the failure characteristics.

• Developing FE-TIRE Model for Road Noise Simulation

  Masaki SHIRAISHI - SRI R&D Ltd., Kimihiro HAYASHI - The Japan Research Institute,Limited

• Developing FE-Tire Model Library for Durability and Crash Simulations

  Masaki Shiraishi, Naoaki Iwasaki - Sumitomo Rubber Industries, LTD, Tomoharu Saruwatari, Kimihiro Hayashi - The Japan Research Institute,Ltd.

• Development & Validation of a Finite Element Model for a Mid-Sized Passenger Sedan

  D. Marzougui, D. Brown, H.K. Park, C.D. Kan, and K.S. Opiela (George Mason University)

  A Finite Element (FE) model of a mid-size passenger sedan was created by reverse engineering to represent that aspect of the fleet in crash simulation analyses. A detailed FE model of this vehicle was created to allow application for different types of crash scenarios. The initial version of the model includes detailed and functional representation of suspension and steering components. Material characteristics and thicknesses of the different components were determined from manufacturer’s information and coupon tests so that the simulated crash behavior would reflect actual impact test results. The model mass and inertial properties were compared to measurements made on the actual vehicle. Initially, the model was subjected to a series of debugging and verification simulations to insure that all components of the vehicle are included and appropriately connected. A series of validation tests followed to compare simulated and actual crash tests. Comparisons to full-scale crash tests indicated that acceleration pulses at different locations of the vehicle, deformations in the occupant compartment, and overall vehicle kinematics are similar. Detailed representation of the vehicle interior components and restraint systems is currently being incorporated in the model to provide opportunities to use FE occupant models in the vehicle and assess injury risks.

• DEVELOPMENT AND EVALUATION OF A CONTINUUM NECK MUSCLE MODEL

  S. Hedenstierna, P. Halldin, K. Brolin - Royal Institute of Technology, Stockholm, Sweden

  The Finite Element method is a powerful tool for analyzing the biomechanics of the human body. One area that has attracted increasing attention is the cervical musculature and its influence in neck injury mechanisms. Most cervical FE models of today use spring-elements as muscles and are limited to discrete geometries and nodal output results. A solid-element muscle model however, will improve the geometry and add properties such as tissue inertia and compressive stiffness. It also enables analysis of element stresses and strains within the muscular tissue. The aim of this study was to determine how a continuum muscle model influences the impact behavior of a human neck FE model compared to a discrete muscle model. The 3D geometries of the neck muscles were digitized from MR images of 50th percentile males and positioned relative to the KTH FE neck model in line with anatomical data from the literature. The muscles were modeled using solid finite elements and a non-linear, viscoelastic continuum material model. The behavior of the new muscle model during impact was compared to an existing discrete muscle model for frontal, rear-end, lateral and oblique impacts. The continuum muscle model stiffened the response of the KTH neck model and improved the boundary conditions for the vertebral column compared to a discrete model.

• Development and Implementation of an Advanced User Material Model for UHMWPE

  J.S. Bergström, A.E. Bowden - Exponent, Inc, C.M. Rimnac - Case Western Reserve University, USA, S.M. Kurtz - Drexel University, USA

  Ultra-high molecular weight polyethylene (UHMWPE) is a semi-crystalline polymer with excellent strength, impact resistance, and abrasion resistance. These mechanical properties have led to extensive use of UHMWPE as a bearing material in total joint replacements. In order to accurately capture the experimentally observed response of this important polymer we have developed a new advanced material model—the Hybrid Model (HM). This constitutive model is physically motivated and based on a decomposition of the deformation gradient into elastic and viscoplastic components. The elastic response of the underlying molecular network is captured using the eight- chain hyperelastic model, and the viscoplastic response is represented using energy activated flow driven by the molecular reorganization that occurs during large deformations. The constitutive theory for the HM has been implemented as a user-material model (UMAT) for ls971 and is available for both explicit and implicit simulations. For optimal accuracy and numerical efficiency the UMAT uses a forward Euler integration scheme for explicit simulations, and a higher order backward differentiation formula (BDF) method for implicit simulations. The HM was calibrated to data from uniaxial tension experiments performed at different strain rates and with different loading-unloading segments. For validation, the calibrated HM was then used to simulate a small punch test. A direct comparison between the experimental data and model predictions of the calibration and validation data demonstrate that the HM accurately captures the non-linear response of UHMWPE. The ability to simulate large-scale contact problems was examined by simulating the deformation behavior of a total knee replacement component and the CharitéTM artificial discs.

• Development and Implementation of a Composite Material Shell-Element Model

  Tobias Achstetter, Paul Du Bois, Kelly Carney, Cing-Dao Kan (George Mason University), Allen Sheldon (Honda R&D Americas), Sheng Dong (The Ohio State University), Gunther Blankenhorn (Livermore Software Technology Corporation)

  While the response to loading of traditional engineering materials, such as plastics and steel, is well understood and can be simulated accurately, designers of composite structures still rely heavily on physical testing of components to ensure the requirements of load bearing capabilities are met. The majority of composite material models that have been developed rely on non-physical material parameters that have to be calibrated in extensive simulations. A predictive model, based on physically meaningful input, is currently not available. The developed orthotropic material model includes the ability to define tabulated hardening curves for different loading directions with strain-rate and temperature dependency. Strain-rate dependency was achieved by coupling the theories of viscoelasticity and viscoplasticity to allow for rate dependency in both the elastic and plastic regions of the material deformation. A damage model was implemented, where a reduction of stiffness and stress degradation in the individual material directions can be tracked precisely. Modeling of failure and Finite Element erosion was achieved by implementing a new strain-based generalized tabulated failure criterion, where failure strains can be precisely defined for specific states of stresses. Composite materials are generally used in a layup of plies with different fiber directions. These individual plies are very thin, which leads to impractically small mesh sizes when modeled with three dimensional solid elements. The developed material model is, therefore, made available for shell elements. The presented material model is a step towards the goal of a truly predictive material model for composite materials.

• Development and Validation of Bolted Connection Modeling in LS-DYNA ® for Large Vehicle Models

  Michalis Hadjioannou, David Stevens, Matt Barsotti (Protection Engineering Consultants LLC)

  As part of the United States Marine Corps (USMC) Mitigation of Blast Injuries through Modeling and Simulation project, Protection Engineering Consultants performed numerical and experimental investigations to develop modeling approaches for bolted connections. Vehicle models require efficient yet accurate methods to represent bolted connections, especially under extreme loading situations where connection behavior may have crucial impact on the accurate prediction of the response. Efficient connection models require relatively coarse mesh sizes and computationally cheap element types that allow modeling large numbers of connections in vehicle models. This paper describes the development and validation of reduced bolted connection models that utilize a combination of beam and shell elements. The models were developed and validated with data from bolted connections that were tested under static and dynamic loading conditions. The tests provided valuable data for the refinement of the models, which are shown capable of simulating connection behavior up to and including rupture. Important aspects of the modeling procedure are highlighted including contact definitions and bolt preloading, as well as inherent limitations that exist in such models. The study also demonstrates the importance of material failure parameters such as triaxiality-dependent and strain-rate-dependent fracture. These parameters influence not only the connection capacity but also the absorbed energy before the connection fails. Considerations of the absorbed energy are crucial when assessing the safety of occupants in vehicles under extreme loading conditions.

• Development and Validation of a Finite Element Model of an Energy-absorbing Guardrail End Terminal

  Yunzhu Meng, Costin Untaroiu, Department of Biomedical Engineering and Virginia Tech, Blacksburg, VA, USA

  Guardrail end terminals are installed along roads to minimize the severity of vehicle crashes by avoiding their contact with fixed objects along the road. Energy-absorbing guardrail end terminals are designed to help preventing the rail from spearing through the car in an end-on collision as well as to dissipate significant amounts of the striking vehicle energy after the collision while keeping the rate of deceleration tolerable for the occupants. The main objective of this study was to develop and validate a Finite Element (FE) model for a common guardrail end terminal (ET-Plus). Although several standard impact tests have been performed on ET-Plus, few efforts were dedicated to develop a high-fidelity FE model that can facilitate investigation of its performance under various conditions. In this study, a computational efficient FE model of ET-Plus end terminal was developed in LS-DYNA®. The dimensions were collected from published design drawings and the dimensions of a mounted end terminal were recorded and used as supplementary in this model. Material types were identified based on a previously published patent and material parameters were estimated from literature. FE simulations of Car-to-ET-Plus collisions were performed in LS-DYNA based on the NCHRP-350 test conditions to validate the end-terminal model. The end terminal model developed in this study predicted the full energy absorbing mechanism during the collision using simple impactor. In addition, the ET-Plus model showed numerical stability during small car impact simulations. Compared with a car impact test data (1/4 offset, 27 in guardrail height, test 27-30), the simulated yaw angles showed a good agreement with the average error less than 3°. In a second offset test (1/4 offset, 31 in guardrail height, test 31-30), the car model showed higher values of yawn angle than the tested car. Overall, a computationally efficient FE model of ET-Plus end-terminal was developed in this research. This model can be used by safety researchers to improve the design of new vehicles front ends and new guardrail end terminals for better protection of vehicle occupants.

• Development and Validation of a 95 th Percentile Male Pedestrian Finite Element Model

  Wansoo Pak, Costin D. Untaroiu (Virginia Tech)

  The pedestrian is one of the most vulnerable road users. Given an impact event, the probability of a pedestrian fatality in a traffic crash is almost two times higher than that for a vehicle occupant. Therefore, pedestrian protection regulations which involve subsystem tests in car-to-pedestrian collisions (CPC) have been proposed in Europe and Asia. In addition, human finite element (FE) models have been developed to better understand the whole vehicle- pedestrian interaction, and assess the pedestrian injuries. However, the majority of these human th models represent a 50 percentile human, so their responses cannot be extrapolated to understand the responses of pedestrian with other anthropometries during a CPC. The main goal of this study was to develop and validate a FE model corresponding to a 95 th percentile male (M95) pedestrian. The model mesh was developed by morphing the Global Human Body Models Consortium (GHBMC) 50 th percentile male (M50) pedestrian model to the reconstructed geometry of a human subject having 194 cm height and 103 kg weight. The material properties of the M95 pedestrian model were assigned based on GHBMC M50 occupant model. The knee joint and upper torso of the FE model were preliminarily validated against Post Mortem Human Surrogate (PMHS) test data recorded in four-point knee bending tests and upper body blunt lateral impact tests. Then, pedestrian-to-vehicle impact simulations were performed using the whole pedestrian model and the results were compared to corresponding pedestrian PMHS tests. Overall, the results generated by the FE model showed to be well correlated to test data. Therefore, the model could be used to investigate various pedestrian accidents or to improve vehicle front end design for pedestrian protection.

• Development and Validation of a Headform Impactor Finite Element Model with Application to Vehicle Hood Design for Pedestrian Protection

  Costin Untaroiu, Jaeho Shin, Jeff Crandall, Scott Crino - University of Virginia

  Head injuries are the most common cause of pedestrian deaths in car-to-pedestrian collisions. To reduce the severity of such injuries, international safety committees have proposed subsystem tests in which headform impactors are impacted upon the car hood. In the first part of the paper, the development and validation of an adult headform impactor finite element (FE) model is presented. The skin material model was assumed as viscoelastic and its parameters were identified by FE optimization to match the quasi-static and dynamic test data reported in literature. Overall, it was shown that the geometrical and inertial characteristics of the headfom FE model developed in this study satisfy the regulations of international safety agencies. The second part of the paper presents results of a hood optimization using simulations of the headform-hood impact test. A generic hood design was assumed consisting of two plates connected by buckling structures. The reductions of head injury risk under impact and the under-hood clearance space were included in an optimization problem which considered the geometry of connecting spools and the panel thicknesses as design variables. The automatic design process was shown to converge to an optimum design after several iterations. The methodology and recommendations for future work presented in this paper may assist in the hood design of new car models to reduce pedestrian head injuries and meet new safety requirements.

• DEVELOPMENT AND VALIDATION OF A US SIDE IMPACT MOVEABLE DEFORMABLE BARRIER FE MODEL

  Abdullatif K. Zaouk, Dhafer Marzougui - The George Washington University

  Automotive safety regulations vary in different parts of the world. Dynamic side impact regulations, for example, are different than the ones in Europe. United States National Highway Traffic Safety Administration (NHTSA) and the European Union (EU) have each produced their own distinct testing procedures such as different deformable barriers, impact configurations and anthropomorphic test devices (dummies). Although both test procedures have the same final objective, estimate occupant responses in side impact, they differ greatly in execution. One of the main differences in testing is the Moving Deformable Barrier (MDB) used. The US MDB is designed to represent an average midsize vehicle in the US market, while the European MDB represents a mid size vehicle in Europe. The objective of this paper is to develop a finite element model representing the US deformable barrier for use in side impact simulations. Special emphasis is made on using the various available material models in LS-DYNA and the correct adhesive properties to predict the correct behavior of the honeycomb material. These models are validated to available full-scale tests. As known by many researchers, the main difficulty of MDB modeling is the prediction of the barrier complex failure modes. In side impact tests, the severe shear deformation of the honeycomb material, full densification of barrier edge, rupture of aluminum cover sheets, and tearing of honeycomb blocks are often observed. This complex pattern of honeycomb material failure mode makes it difficult to predict. Numerical instabilities, such as negative volume, sever hourglassing, and inaccurate predictions are often experienced.

• Development and Validation of Numerical Pedestrian Impactor Models

  Thomas Frank - Daimler Chrysler AG, Artur Kurz - LASSO Ingenieurgesellschaft mbH, Martin Pitzer - PENG GmbH, Michael Söllner - Porsche AG

• Development and verification of a material model for prediction of containment safety of exhaust turbochargers

  Dieter Memhard , Florence Andrieux , Dong-Zhi Sun - Fraunhofer Institute for Mechanics of Materials IWM, R. Häcker - Bundesanstalt für Materialforschung und –prüfung BAM

  For predicting the containment safety of turbochargers against failure of rotors at elevated temperatures and dynamic loading the complex deformation and damage behaviour of the respective materials has to be determined by appropriate experiments and on the other hand the temperature and strain rate dependency has to be described by a material model to simulate the component behaviour under these complex loading conditions. The investigations focus on the cast iron alloy EN-GJS-400 with nodular graphite. Its mechanical behaviour under uniaxial and multiaxial tension as well as under compression and shear loading has been investigated for a variety of loading rates and temperatures. For the numerical modelling of the containment safety of turbochargers a material model has been developed with the capability to describe the specific deformation behaviour of casting materials, e.g. different properties under tension and compression, temperature and strain rate dependence. The deformation behaviour was described with a model for thermally activated flow and the damage behaviour with a Johnson-Cook type model and an extended failure model (bi-failure model) respectively. The material model has been verified by numerical simulations of penetration tests under highly dynamic impact loading conditions. Also a containment test on a turbocharger was simulated.

• Development and Verification of an Orthotropic Elasto-Plastic Three-Dimensional Model with Tabulated Input Suitable for Use in Composite Impact Problems

  Robert K. Goldberg, NASA Glenn Research Center, Cleveland OH;, Kelly S. Carney and Paul DuBois, George Mason University, Fairfax VA;, Bilal Khaled, Loukham Shymasunder, Canio Hoffarth and Subramaniam Rajan, Arizona State University, Tempe AZ;, Gunther Blankenhorn, Livermore Software Technology Corporation, Livermore CA

  A material model which incorporates several key capabilities which have been identified by the aerospace community as lacking in the composite impact models currently available in LS-DYNA® is under development. In particular, the material model, which is being implemented as MAT 213 into a tailored version of LS-DYNA being jointly developed by the FAA and NASA, incorporates both plasticity and damage within the material model and utilizes experimentally based tabulated input to define the evolution of plasticity and damage as opposed to specifying discrete input parameters (such as modulus and strength. The plasticity portion of the orthotropic, three-dimensional, macroscopic composite constitutive model is based on an extension of the Tsai-Wu composite failure model into a generalized yield function with a non-associative flow rule. The capability to account for the rate and temperature dependent deformation response of composites has also been incorporated into the material model. For the damage model, a strain equivalent formulation is utilized to allow for the uncoupling of the deformation and damage analyses. In the damage model, a diagonal damage tensor is defined to account for the directionally dependent variation of damage. However, the terms in the damage matrix are semi-coupled such that the damage in a particular coordinate direction is a function of the stresses and plastic strains in all of the coordinate directions. For the failure model, a tabulated approach is utilized in which a stress or strain based invariant is defined as a function of the location of the current stress state in stress space to define the initiation of failure, which allows an arbitrarily shaped failure surface to be defined. A wide ranging series of verification studies on a variety of composite systems has been carried out.

• Development New MAT Applied Yoshida 6th Order Yield Function and its Verification

  H. Fukiharu, T. Amaishi (JSOL)

  Sheet metal forming simulation has become an indispensable tool for design of automobile parts and process design of its die. As for automobile parts, high strength steel and aluminum alloy are applied for them in progress. On the other hand, these lightweight materials are well known as difficult formability, and many problems have occurred in stamping process. In elasto-plastic FEA, there are many factors that determine the analysis accuracy, the material model is especially important. In case of applying associated flow rule, the yield function is key, and the reproductive capability of the material properties are very significant and influential. In LS-DYNA, there are many material models, and various yield function can be applied. MAT36(Barlet’89), MAT37(Hill’48), MAT242(Ylld2000-2D) [1] are commonly used in sheet metal forming. And this time, the MAT model that uses Yoshida 6th order yield function [2] are developed by using USER MATERIAL function in order to improve the accuracy. This MAT model take Yoshida-Uemori kinematic hardening model which is well known to be able to properly reproduce Bauschinger effect into account. And it can also strain dependency of Young’s modulus into account. This yield function is applicable with 16 parameters both to shell elements as well as solid elements, therefore this model is user-friendly for users from this point of view. In addition, it is easy to consider anisotropic hardening which is important factor for accuracy. This model was implemented as MAT_289. In order to verify the analysis accuracy of this material model, the benchmarks of NUMISHEET 2018 [3] are calculated and the calculation results are compared with experimental data. Good results are also obtaine when shell elements are used and another case where application of solid elements are necessary. In this paper, the analysis results of MAT289 or the other MAT models are compared with experimental results.

• Development of a 50th Percentile Hybrid III Dummy Model

  Cing-Dao (Steve) Kan, Dhafer Marzougui, Nabih E. Bedewi - The George Washington University

  Due to significant improvements in computer technology and finite element (FE) code capabilities, it has become more feasible and effective to incorporate occupant models in the analysis and evaluation of vehicle crashworthiness and safety. Using Detailed FE models that incorporate the vehicle, restrains systems, and occupants, in automotive safety analyses have shown advantages over the traditional methods where the vehicle and occupants are uncoupled. This paper describes a finite element model of a 50 percentile Hybrid III dummy. The model was developed with several fundamentals in mind. First the resulting FE model must accurately represent the actual dummy. This is accomplished by incorporating correct geometry, material properties, and connectivity for all components. Second, the dummy model should be easily positioned and incorporated in vehicle and vehicle compartment models. This is achieved by using a systematic scheme for numbering and organizing the parts and joints in the model. The model should also be efficient, robust, and reliable. For this, special modeling techniques, such as using a uniform mesh for all important components and using one “automatic single surface interface” to treat the contact between all dummy components are incorporated in the model.

• Development of a 2015 Mid-Size Sedan Vehicle Model

  R. Reichert, S. Kan (George Mason University)

  A detailed finite element model of a 2015 mid-size sedan vehicle was developed using a reverse engineering process. The model consists of about 1000 parts and 2.25 million elements representing geometry, connections, and material characteristics of relevant structural and interior components. This paper describes the level of detail of the simulation model, the validation process, and how it performs in various impact configurations when compared to full-scale crash test data. Members of the Center for Collision Safety and Analysis (CCSA) at George Mason University, formerly known as the National Crash Analysis Center (NCAC), have been developing a fleet of finite element vehicle models over the last 20 years. The updated mid-size sedan presented in this paper is the latest model with a high level of detail using state-of-the-art modeling techniques. A thorough validation process, using test results from frontal, side, and roof crush impact configurations, ensures a high level of correlation for a variety of load cases. Special focus has been placed on occupant compartment intrusion and vehicle pulse evaluation for frontal impact scenarios. Realistic wheel kinematics in the Insurance Institute for Highway Safety (IIHS) small overlap load case was achieved through adequate failure modeling. An objective correlation analysis tool was used to evaluate how well simulation results match respective test results. The model is currently being used for several research studies, including the development of structural countermeasures to significantly reduce occupant compartment intrusion for the National Highway Traffic Safety Administration’s (NHTSA) left and right frontal oblique offset configurations.

• Development of a 2020 SUV vehicle FE model

  Rudolf Reichert, Umashankar Mahadevaiah, Cing-Dao (Steve) Kan, Lukas Fuchs

  Finite element (FE) vehicle models allow researchers to conduct diverse simulation studies. Members of the Center for Collision Safety and Analysis (CCSA) at the George Mason University (GMU), that also built the core team of the formerly known National Crash Analysis Center (NCAC), have been developing a fleet of publicly available FE vehicle models [1] over the past 25 years. This paper describes the latest model, representing a 2020 Nissan Rogue SUV vehicle, shown in Figure 1. Note that the vehicle has been named as the Nissan X-Trail in all countries it is sold, except for the United States and Canada, where it called Nissan Rogue.

• Development of a coupled electro-mechanical model of cylindrical cell LR61 batteries with LS-DYNA ®

  Abigail Schauer, Megan Gober, William O’Donoghue, Nathan Spulak, George Nelson

  In-depth characterization of the mechanical and electrical response of an LR61 alkaline battery is performed, for incorporation into a coupled electro-mechanical battery model using LS-DYNA. Tension tests are performed on the outer metal casing to develop a plasticity model, and a Bayesian Model Calibration analysis is performed to determine crushable foam model parameters for the interior anode, cathode, and separator battery components. Electrochemical impedance spectroscopy, distribution of relaxation times, and Kramers-Kronig analysis are used to determine the electrical response of the battery during incremental crush tests. X-ray imaging is also utilized to determine the dimensions of the inner battery components, and to gain insight into the geometric changes to these individual components that occurs during crushing and the corresponding changes to the electrical behavior. This data is used to determine the required order of a Randles circuit necessary to accurately model the electrical behavior. This experimental data is then incorporated into a solid element LS-DYNA model of the battery utilizing the MAT_24 and MAT_63 material models and the EM_RANDLES_SOLID electrical circuit model.

• DEVELOPMENT OF A COUPLED FINITE ELEMENT AND MESH-FREE METHOD IN LS-DYNA

  Cheng-Tang Wu - Livermore Software Technology Corporation, Mark E. Botkin, Hui-Ping Wang - GM R & D Center

• Development of a Customized Beam-to-Shell Element Model Mapping Tool

  M. Duhovic, P. Patil, D. Scheliga, D. Schommer, L. Münch, J. Hausmann (Institut für Verbundwerkstoffe)

  A customized solution enabling the mapping of fiber orientations represented by beam elements in organic sheet materials from one simulation phase to another of the product development cycle has been developed using python scripting language. The strategy implemented for the mapping of the fiber orientations is based on the modeling approaches used for the input models in both types of simulation. The thermoforming simulation model consists of beam and shell elements representing the fiber and polymer layers in an organic sheet respectively while in the structural simulation, the component is usually modeled using only shell elements. The thermoforming simulation results (a .d3plot mesh) and structural simulation model input mesh are provided as inputs to the so called “BETA Mapper script”. The script segregates elements from each model into discrete volumes enabling parallel processing of the mapping procedure. The centroid coordinates of the elements from each matching cuboid are used to identify element pairs by finding the shortest distance between two element centroids. During the thermoforming process, the fibers, in the warp and weft directions of an organic sheet undergo a relative scissoring motion. In order to take this effect into consideration and to capture non-orthogonal fiber directions, the script is developed to produce three solutions and provides the possibility for mapping various types of part geometries. Developable geometries, which can be unfolded as a flat surface and do not exhibit any relative fiber scissoring, are mapped according to “Solution 1” and the part can then be simulated using assigned orthotropic material properties. “Solutions 2” and “3” implemented in the script, provide a methodology to enable the mapping of fiber orientations in two non-orthotropic directions in a single mesh model, which is not feasible with the generic approach using only one definition of the keyword (*PART_COMPOSITE). Additionally, “Solution 2” implemented in the script provides the user with the flexibility to choose the number of individual parts to be generated during the mapping. The method facilitates the realization of correctly mapped fiber orientations of the warp and weft yarns of an organic sheet in a single mesh model. With its three solutions, the “BETA Mapper script” provides the required data integrity between the different phases of organic sheet virtual product development and enables overall improvement in product design.

• Development of a Data-driven Surrogate Model for Scale-bridging in Battery Modelling Application

  Harshwardhan Dhumal, Tobias Aubel, David Koch, Nils Karajan, Karsten Keller, Andre Mielke

  In numerous mechanical engineering applications, the use of multiscale computational modeling and simulations is imperative. Nevertheless, the computational challenge persists in addressing complex multiscale systems due to the vast dimensionality of the solution space. The field of machine learning (ML) has experienced ongoing development as a feasible option that might potentially expedite, substitute, or complement traditional numerical techniques.

• DEVELOPMENT OF A FINITE ELEMENT MODEL OF THE HUMAN BODY

  Fuminori Oshita - The Japan Research Institute Ltd., Kiyoshi Omori, Yuko Nakahira, Kazuo Miki - Toyota Central R&D Labs, Inc.

  A finite element human model, THUMS (Total HUman Model for Safety), was developed in order to study human body responses to impact loads. This paper briefly describes the structure of the human model, as well as some of the results of the simulations conducted to validate the model.

• Development of a Finite Element Model of the WIAMan Lower Extremity to Investigate Under-body Blast Loads

  Wade Baker, Costin Untaroiu (Virginia Tech), Mostafiz Chowdhury (US Army Research Laboratory)

  Occupants of military vehicles are likely to be subjected to an under-body blast (UBB) resulting from anti – vehicular land mines and improvised explosive devices (IEDs). For years the automotive industry has successfully used human anthropomorphic test devices (ATDs) to help quantify the occupant injury risk over a wide range of impact scenarios. However, it has been proven that these ATDs are inadequate when it comes to accurately measuring the response of the human to under-body blast loading. Therefore, a new dummy concept, called WIAMan (Warrior Injury Assessment Manikin) is being developed together by various research institutions and industry leaders. A numerical model of the lower leg was developed in LS- DYNA ® based on CAD geometry of the dummy. Material models in LS-DYNA were assigned based on high and low strain-rate tests to model the viscoelastic behavior of the soft tissue used to represent the flesh, heel pad, foot plate, and tibia compliant element of the dummy leg. The WIAMan FE model was simulated under identical conditions as the experiments done on the physical dummy. A comparison between the outputs from the simulation and the test data was used to validate the unbooted WIAMan lower extremity (WIAMan-LX) model. The proposed numerical models of materials exhibiting viscoelastic responses show good correlation to the test data at both high and low strain rates. Simulations of the entire WIAMan-LX correlate well to the WIAMan physical dummy tests. Additionally, a comparison of the WIAMan to Hybrid-III and post-mortem human surrogate (PMHS) tests is presented. Future work includes further validation of the model and correlating the responses of the dummy to risk of human injury.

• Development of a Finite Element Model of a Motorcycle

  N. Schulz, C. Silvestri Dobrovolny and S. Hurlebaus (Texas A&M Transportation Institute)

  Over the past years, extensive research efforts have been made to improve roadside safety hardware to reduce injury to occupants of four wheel vehicles and heavy trucks. In comparison, limited research has been conducted to address the safety of motorcycle riders when impacting roadside safety hardware. The vulnerability of motorcycle riders can lead to a high risk of injury for the rider, especially when impacting roadside barriers. In real-world motorcycle crashes there is a wide range of impacts against other vehicles and barriers. Reproducing these different motorcycle crash scenarios through physical crash testing can be considerably costly and time consuming. Computer simulations are a great tool to address the wide range of impacts in real world motorcycle crashes because they are significantly cheaper and quicker than performing full scale crash tests. Motorcycle simulation models have been developed since the 1970’s and have improved in detail and complexity over the years. However, there is still a need to develop detailed motorcycle models that are geometrically accurate and can accurately predict motorcycle response behavior. The researchers have developed a Finite Element (FE) computer model of a motorcycle through reverse engineering. This model can be used to investigate impact scenarios involving motorcycles. To validate the accuracy of the model, measurements of the motorcycle computer model such as mass, geometry, etc, were compared to measurements of the physical motorcycle.

• Development of a finite element model of high energy laser-material interaction

  M. Ross, D. Pope (Dstl)

  A thermomechanical modelling technique was developed using LS-DYNA for simulating the heating and subsequent erosion of metallic elements by a continuous wave laser beam. Accurate representation of the laser-material interaction requires inclusion of several physical phenomena.

• Development of a Flex-PLI LS-DYNA Model

  Shinya Hayashi - JSOL Corporation, Masahiro Awano, Isamu Nishimura - Mitsubishi Motors Corporation

  A biofidelic flexible pedestrian legform impactor (Flex-PLI) has been developed by Japan Automobile Manufacturers Association, Inc. (JAMA) and Japan Automobile Research Institute (JARI). The Flex-PLI has good biofidelity as well as several knee ligament elongation measurement capabilities, three femur and four tibia bending moment measurement capabilities. For these reasons Flex-PLI is likely to be used for future pedestrian Global Technical Regulation. This paper introduces a finite element model of the Flex-PLI type GT for LS-DYNA and compares a full vehicle Flex-GT impact simulation with test. A very accurate vehicle model is needed to predict Flex- PLI injuries. In this paper, a detailed and correlated vehicle model was used. The Type GT is the 5th version of Flex-PLI and has almost the same structure and performance as final design type GTR. The Flex-PLI type GT LS-DYNA model was carefully created to ensure every important detail was included. Geometries, masses and material properties of all parts were reproduced from drawings and inspection of the real components. Connectivity and component interaction within the model was determined by thorough experiments. Accurate prediction of injury indices and kinematic behaviour was achieved by correlation to static and dynamic calibration tests. A fine mesh was used but reasonable calculation cost assured by imposing an analysis time step of 0.9 micro seconds.

• Development of a Flex-PLI LS-DYNA Model

  Shinya Hayashi - JSOL Corporation, Masahiro Awano, Isamu Nishimura - Mitsubishi Motors Corporation

  A biofidelic flexible pedestrian legform impactor (Flex-PLI) has been developed by Japan Automobile Manufacturers Association, Inc. (JAMA) and Japan Automobile Research Institute (JARI). The Flex-PLI has good biofidelity as well as several knee ligament elongation measurement capabilities, three femur and four tibia bending moment measurement capabilities. For these reasons Flex-PLI is likely to be used for future pedestrian Global Technical Regulation. This paper introduces a finite element model of the Flex-PLI type GT for LS-DYNA and compares a full vehicle Flex-GT impact simulation with test. A very accurate vehicle model is needed to predict Flex- PLI injuries. In this paper, a detailed and correlated vehicle model was used. The Type GT is the 5th version of Flex-PLI and has almost the same structure and performance as final design type GTR. The Flex-PLI type GT LS-DYNA model was carefully created to ensure every important detail was included. Geometries, masses and material properties of all parts were reproduced from drawings and inspection of the real components. Connectivity and component interaction within the model was determined by thorough experiments. Accurate prediction of injury indices and kinematic behaviour was achieved by correlation to static and dynamic calibration tests. A fine mesh was used but reasonable calculation cost assured by imposing an analysis time step of 0.9 micro seconds.

• Development of a Full Human Body Finite Element Model for Blunt Injury Prediction Utilizing a Multi-Modality Medical Imaging Protocol

  F. S. Gayzik, D. P. Moreno, N. A. Vavalle, A. C. Rhyne, J. D. Stitzel (Wake Forest University School of Medicine, Virginia Tech)

  Computational modeling is an increasingly important tool in the study of injury biomechanics. This paper describes the development and validation of a seated human body finite element model as part of the Global Human Body ®Models Consortium (GHBMC) project. The model was developed using LS-DYNA (LSTC, Livermore, CA) and is intended for blunt injury prediction. The geometry of the model is ba sed on a protocol that leverages the strengths of three clinical scanning methods; computed tomography (CT), magnetic resonance imaging (MRI), and upright MRI (i.e. subject in seated position). The protocol was applied to a living male volunteer (26 years, height, 174.9 cm, and weight, 78.6 kg) who met extensive anthropometric and health criteria. Computer Aided Design (CAD)) data were developed from the images, containing significant anatomical detail. Seventeen sub-substructures of the brain, 52 muscles of the neck, and all major organs of the thorax and abdomen, with associated vasculature, are represented in finite element model. The positioning of the axial skeleton and the location of organs were determined using upright MRI scans to represent the seated posture. A region-specific development approach was used, with five Body Region Centers of Expertise (COEs) focused on meshing and regional validation of the head, neck, thorax, abdomen, pelvis and lower extremity. The regional models were then integrated into a full body model. Mesh connections between neighboring body regions were assembled using techniques based on the geometry, element type, and anatomic purpose. This consisted of nodal connections for all 1-D beam and discrete element connections (e.g. ligamentous structures), 2D shells (e.g. the inferior vena cava to right atrium), and many 3D tetrahedral and hexahedral structures (e.g. soft tissue envelope connections between body regions). In cases where node-to-node connections were not made, (e.g. 3D muscle to bone insertions), contact definitions were implemented. The integrated full body model consists of 1.3 million nodes, and 1.9 million elements. Element types in the model are 41.0 % hexahedral, 33.8 % tetrahedral, 19.5 % quad shell, 5.1% tri shell, and 0.6 % others including beam and discrete elements. Non-linear and/or viscoelastic material models were used where appropriate. Simulations were conducted using MPP LS-DYNA R.4.2.1. The model has been validated against a number of frontal and lateral rigid impactor and sled tests. Two of these (a chest impact per Kroell and an abdominal impact per Hardy) are highlighted via computational benchmarking on a computational cluster running Red Hat Enterprise Linux 4.0. Benchmarking tests ranged from 8 to 88 nodes. Reductions in compute times are seen up to 80 CPUs. Using 64 CPUs, solution times for the 60 ms chest impact and 100 ms abdominal impact were 10 hours, 45 minutes and 12 hours, 10 minutes respectively. Through the use of a living subject, comprehensive image data, and extensive geometric validation, this model has the potential to provide a greater degree of accuracy in blunt trauma simulations than existing human body models. It will serve as the foundation of a global effort to develop a family of next-generation computational human body models for injury prediction and prevention.

• Development of a Fully-Tabulated, Anisotropic and Asymmetric Material Model for LS-DYNA (*MAT_264)

  S. Haight, C.-D. Kan (George Mason University), P. Du Bois (Consultant)

  The purpose of this research is to develop a fully-tabulated, anisotropic, asymmetric and rate dependent material model for solid elements. Physical tests of several metallic materials have shown to have anisotropic (or orthotropic) characteristics. While many material models in LS-DYNA currently have anisotropic modeling options, they are typically focused on the material forming applications – not crash and impact analysis. Unlike most anisotropic forming material models, this model will have: rate dependency, temperature dependency, tabulated hardening (as opposed to parameterized inputs), associated flow, directional tensile compressive asymmetry and the ability to maintain stability for large deformations.

• Development of a Hybrid Energy Absorbing Reusable Terminal (HEART) Using Finite Element Modeling in LS-DYNA for Roadside Safety Applications

  Nauman M. Sheikh, Dean C. Alberson, D. Lance Bullard - Texas Transportation Institute

  The Hybrid Energy Absorbing Reusable Terminal (HEART) is a newly developed crash cushion or an end terminal to be used in highway safety applications that will mitigate injuries to occupants of errant vehicles. The HEART is composed of corrugated plates of High Molecular Weight/High-Density Polyethylene (HMW/HDPE), supported on steel diaphragms, which slide on a fixed rail. Kinetic energy from errant vehicles is converted to other energy forms through the folding and deformation of HDPE material. Many previous designs utilize the plastic or permanent deformation of plastics or steels to accomplish this goal. However, HEART is a reusable and self- restoring crash cushion, and therefore has a major cost advantage over the conventional crash cushion designs. HEART has been designed and optimized through an extensive use of finite element modeling. The objective of this paper is to present the finite element modeling and simulation approach adopted to arrive at the final design of the HEART cushion. In order to meet the National Cooperative Highway Research Program (NCHRP) Report 350 guidelines, all roadside safety devices need to pass the report’s requirements from an 820 Kg and a 2000 Kg vehicle impacting at 100 Km/h. For HEART to meet the NCHRP Report 350 evaluation criteria, a large number of design parameters were investigated. Among these were the thickness of the HDPE plates, the height of the plates, the length of the plates between two consecutive steel diaphragms, etc. Initially, simple finite element models were developed using beam elements as HDPE plates in LS-DYNA. A large number of configurations were tested with these simple models to gain an insight to the problem and to narrow down the number of parameters. Later on, detailed finite element models with shell elements as HDPE plates were developed to come up with the final configuration of the device. HEART crash cushion has passed the full-scale test requirements in accordance with guidelines presented in NCHRP Report 350. Development of the HEART cushion is a good example of the use of finite element analysis as a tool for analysis, design and optimization of roadside safety devices.

• Development of a New Method for Strain Field Optimized Material Characterization

  M. Benz, J. Irslinger, M. Feucht (Daimler), P. Du Bois (Consultant), M. Bischoff (University of Stuttgart)

  Due to technical progress, cars of the future will consist of even more different materials than they already do today. Especially plastic materials will experience a further increase of importance, as they provide advantages such as a low density and the freedom to shape them unconventionally. In view of this trend, it is essential to improve the quality of predictions derived from corresponding simulations. Modelling the material in an appropriate way is crucial when simulating a component. While in case of metals plastic deformation happens at a constant volume and therefore is easy to describe, this kind of incompressibility does not apply to plastics. Furthermore, the hardening behavior of these materials is usually significantly more complicated. Therefore, complex mechanical descriptions have to be used for the simulation of plastics, which describe hardening and failure in a multiaxial state of stress. Although those models have been available for some time, it is still cumbersome to calibrate their parameters. In particular, the correct prediction of the strain field, which is the key to characterize material failure e.g. with GISSMO [5], is challenging, as a large number of degrees of freedom have to be adjusted simultaneously.

• Development of a New Software Architecture for LS-DYNA Applications

  Tim Palmer (Engineering Technology Associates, Inc.)

  Engineers and researchers are able to carry out complex, multi-physics simulations using LS- DYNA®. The scope of these simulations may include multiple solvers and multiple steps. The variety of simulations available in LS-DYNA® require a complete FE modeling software that allows for creation of all types of elements, materials, contacts and properties. While this complete coverage of all entities is critical, the ability to provide users a unique subset of the complete toolset, to address a specific simulation area, such as fluid-structure interaction or vehicle crash simulations. Inventium is a software architecture that provides both a complete coverage of all LS-DYNA® entities, but is configurable both by software architects and the user, to provide a set of streamlined tools to carry out a specific simulation task. Examples of customized menu systems and application tools will be presented for drop test, fluid structure interaction and vehicle crashworthiness simulations will be presented.

• Development of a Numerical Model of an Anthropomorphic Test Device for the Study of Human Related Impact Events

  Elisa OLDANI, Emanuele FRACASSO, Luigi-M. L. CASTELLETTI, Marco ANGHILERI - Politecnico di Milano, Italia

  The aim of this work is the development and validation of a numerical model of an Anthropomorphic Test Device for the simulation of impact events involving humans and consequently the study and development of crashworthy structures and restraint systems. The research approach consisted in a first validation by subcomponents of the numerical model, comparing the response of the model to the results of experimental tests specifically designed for this purpose. Then, the whole model response was observed and compared to experimental tests reproducing standard tests for the homologation of helicopter seats, in order to validate the model for use in a specific category of impact events. The simulation results showed very good agreement with the experimental tests, proving the Anthropomorphic Test Device numerical model a reliable tool for the analysis of analogous impact events. The model looks also promising for future developments, in particular it is suitable to be further improved in order to be able to reproduce a faithful response in different impact scenarios.

• Development of a One-Step Analysis for Preforming of Woven Carbon Fiber Composites

  aDanielle Zeng, Jeff Dahl, Ford Motor Company, Dearborn, MI, USA;, Xinhai Zhu, Li Zhang, Houfu Fan, Livermore Software Technology Corporation, Livermore, CA, USA

  Carbon fiber reinforced composites are drawing great attention in automotive industry due to their lightweight, high stiffness and strength properties. Carbon fiber prepregs with resin material pre-impregnated in various architectures of fiber fabrics are preformed to a designed part shape before final compression molding of the parts to reduce production cycle time and achieve high product quality. The current numerical simulation techniques are based on the phenomenological models which have difficulty to capture the large shear deformation during the preforming process, and based on the models for incremental simulation which requires long computation time and tooling design information.

• Development of a Process Simulation Model of a Pultrusion Line

  M. Duhovic, P. Aswale, D. Schommer, J. Hausmann (Institut für Verbundwerkstoffe)

  The applications for fiber reinforced plastic (FRP) composite structures have increased tremendously in the automotive and aerospace industries due to their lightweight nature. However, because of their high manufacturing cost, composite structures are typically only used for high-end parts. The reason behind this is the relatively low mass production rate of composite structures. Among the various composite manufacturing methods available, pultrusion is a continuous production process, meaning that the potential for mass production is there, if the process can be made fast enough. The process of pultrusion is defined as extrusion with pulling, in contrast with the conventional ‘extrusion process’, which is used for manufacturing uniform cross section structures such as circular bars, hollow tubes, I section beams etc. [1] [2]. Currently, pultrusion has a wide range of applications in the “architecture, transportation, construction, agriculture, chemical engineering, aircraft, and aerospace industry” [2]. On the basis of the polymer used in the manufacturing process, pultrusion can be divided into two types namely: thermoset and thermoplastic pultrusion. Many studies in the past have been conducted on thermoset pultrusion whose main advantage over thermoplastic pultrusion is the fiber impregnation, or ‘wetting out of the fiber reinforcement’ due to the resin’s low viscosity [3]. On the other hand, thermoplastic pultrusion can create parts which are recyclable, post formable, weldable, have excellent environmental stability and good mechanical properties such as high “fracture toughness, higher damage resistance” [1]. Due to such economic, environmental and mechanical advantages, many researchers have contributed to the development of thermoplastic pultrusion mainly in the field of fiber impregnation with thermoplastic resins [1] [4] [5]. With the advancement in thermoplastic prepreg technologies, pultrusion experiments with pre-consolidated tapes (PCT), powder coated tow-pregs and commingled yarns were performed and studied [1]. Moreover, in the early 1990s, thermoplastic pultrusion models were developed by researchers in order to understand the workings of the process [3] [6]. Most of the current research is focused mainly on investigating the effects of process and material parameters on the mechanical performance of the pultruded part. However, the interrelationship between the materials, process, and product is still not fully understood or has been incorporated into a complete CAE processing chain. The development of analytic, computational, and experimental approaches continues and the need of a fully developed simulation model, which can be used to optimize process parameters, avoid a trial and error approach and to improve productivity still exists.

• Development of a Regression Model for Blast Pressure Prediction in Urban Street Configurations

  Sungmin Lee (Michigan Engineering Services, LLC), Nickolas Vlahopoulos (University of Michigan), Syed Mohammad (Department of Homeland Security)

  Structural damage assessment due to explosive detonations in an urban setting requires a prediction tool for air-blast loads on buildings within the region. In this study, dead-end and cross-roads configurations are considered for blast wave simulations using Multi-Material Arbitrary Lagrange-Eulerian (MM-ALE) with mapping, with aim at developing a prediction model using regression analysis. Variations in street width and charge size and location are considered in constructing these street configurations. For all simulation models we use the uniform building height of 50 m and the identical street length of 50 m, and assume a vehicle bomb, meaning that a charge is carried by a vehicle such as pickup truck and detonates 1.25 m above ground. MM-ALE simulations with mapping, which is available in LS-DYNA®, will be used to achieve accuracy with reasonable amount of computational efforts. Mapping of solutions from 1D to 2D and then from 2D to 3D constitutes our three-step multi-material ALE simulation approach. 1D ALE analysis is performed for the spherically symmetric region between the explosive charge and the ground; 2D ALE analysis for the axi-symmetrical region from explosive location to closest wall; and 3D ALE analysis for the rest of the analysis domain. The ALE mapping approach is validated by comparing its simulation results to experimental data from literature. For the development of a fast running blast model we use regression analysis to estimate the relationship between an important blast simulation output variable (peak pressure) and input variables including street width, explosive size, explosive location, and type of street configuration. Regression analysis results are compared with actual simulation results.

• Development of a Simplified Finite Element Approach for Investigation of Heavy Truck Occupant Protection in Frontal Impacts and Rollover Scenarios

  C. Silvestri Dobrovolny, N. Schulz (Texas A&M University System)

  A finite element model combining a heavy truck conventional-type cabin structure, its interior components, ATD, and passive restraint systems was developed to simulate real-world typical crash scenarios, such as frontal impacts and rollover crashes. These crash scenarios are considered conditions for which there is need and still room for improvement in terms of occupant safety. This paper describes the modeling effort to develop a cabin structure with its interior components through reverse engineering and the development of simplified approaches to replicate finite element computer simulations of frontal impact and rollover scenarios. The model was used to replicate head-on crashes into a rigid barrier at 35 mph which are representative of impact conditions typical of NHTSA NCAP tests. For this crash scenario, an existing FE full tractor-semitrailer model was employed to collect the typical crash pulse resulting from a head-on impact crash. The crash pulse was subsequently applied to defined locations of the new FE cabin model with inclusion of interior components, ATD, and restraint systems. Parametric simulations were then performed by varying characteristics of passive restraint systems and acceleration data from ATD body regions was collected to assist with the calculation of body injury levels for each simulated case. The developed model was also employed to replicate a critical rollover event, determined to be the result of an evasive maneuver followed by an overcorrecting maneuver, with an initial truck speed of 60 mph. To replicate this sequence of maneuvers, a simplified approach was proposed by analyzing truck kinematics through the TruckSim software program. Subsequently, kinematics outputs were applied to the center of the floor of the LS-DYNA® finite element cabin model. The researchers suggest future work to be conducted to address approach limitations, such as validating cabin interiors material models and including cabin deformation, which is not currently incorporated in the simplified proposed approach.

• Development of a Software for the Comparison of Curves During the Verification and Validation of Numerical Models

  Mario Mongiardini, Malcolm H. Ray - Worcester Polytechnic Institute,, Marco Anghileri - Politecnico di Milano

  This paper describes the development of the Roadside Safety Verification and Validation Program (RSVVP), a software that automatically assesses the similarities and differences between two curves. This program was developed to assist engineers and analysts in performing curve comparison during the verification and validation process of a numerical model. RSVVP was designed to automatically preprocess the two input curves to make them comparable. Also, in order to ensure the most accurate comparison as possible, several options are available for the pre-processing of the input curves before the comparison metrics are computed. Data can be filtered and synchronized or any shift/drift effect can be removed. Once the signals have been pre-processed, the user can select to compute the values of one or more of the available sixteen different shape-comparison metrics. Any operation, from the input of the curves and selection of the pre-processing options till the final visualization of the results is accessible through an easy and intuitive graphical user interface. The numerical results are automatically saved by the program into a convenient spreadsheet format and the graphs are saved as bitmap images for any further investigation. Simple examples using an analytical shape are presented to illustrate the characteristics of the metrics. Also, the comparison of the acceleration time histories of a full-scale test involving a small car and the corresponding Ls-Dyna simulation is presented as an example of application of the metrics in the validation process of a numerical model.

• Development of a Software for the Comparison of Curves During the Verification and Validation of Numerical Models

  Mario Mongiardini, Malcolm H. Ray - Worcester Polytechnic Institute,, Marco Anghileri - Politecnico di Milano

  This paper describes the development of the Roadside Safety Verification and Validation Program (RSVVP), a software that automatically assesses the similarities and differences between two curves. This program was developed to assist engineers and analysts in performing curve comparison during the verification and validation process of a numerical model. RSVVP was designed to automatically preprocess the two input curves to make them comparable. Also, in order to ensure the most accurate comparison as possible, several options are available for the pre-processing of the input curves before the comparison metrics are computed. Data can be filtered and synchronized or any shift/drift effect can be removed. Once the signals have been pre-processed, the user can select to compute the values of one or more of the available sixteen different shape-comparison metrics. Any operation, from the input of the curves and selection of the pre-processing options till the final visualization of the results is accessible through an easy and intuitive graphical user interface. The numerical results are automatically saved by the program into a convenient spreadsheet format and the graphs are saved as bitmap images for any further investigation. Simple examples using an analytical shape are presented to illustrate the characteristics of the metrics. Also, the comparison of the acceleration time histories of a full-scale test involving a small car and the corresponding Ls-Dyna simulation is presented as an example of application of the metrics in the validation process of a numerical model.

• Development of a Subcell Based Modeling Approach for Modeling the Architecturally Dependent Impact Response of Triaxially Braided Polymer Matrix Composites

  Christopher Sorini, Aditi Chattopadhyay (Arizona State University), Robert K. Goldberg, and Lee Kohlman (NASA Glenn Research Center)

  Understanding the high velocity impact response of polymer matrix composites with complex architectures is critical to many aerospace applications, including engine fan blade containment systems where the structure must be able to completely contain fan blades in the event of a blade-out. Despite the benefits offered by these materials, the complex nature of textile composites presents a significant challenge for the prediction of deformation and damage under both quasi-static and impact loading conditions. The relatively large mesoscale repeating unit cell (in comparison to the size of structural components) causes the material to behave like a structure rather than a homogeneous material. Impact experiments conducted at NASA Glenn Research Center have shown the damage patterns to be a function of the underlying material architecture. Traditional computational techniques that involve modeling these materials using smeared, homogeneous, orthotropic material properties at the macroscale result in simulated damage patterns that are a function of the structural geometry, but not the material architecture. In order to preserve heterogeneity at the highest length scale in a robust yet computationally efficient manner and capture the architecturally dependent damage patterns, a previously-developed subcell modeling approach is utilized. This work discusses the implementation of the subcell methodology into the commercial transient dynamic finite element code LS-DYNA ® . Verification and validation studies are also presented, including simulating the tensile response of straight sided and notched quasi-static coupons composed of a T700/PR520 triaxially braided (0°/60°/–60°) composite. Based on the results of the verification and validation studies, advantages and limitations of the methodology and plans for future work are discussed.

• Development of a thorax finite element model for thoracic injury assessment

  Nestor N. Nsiampa, C. Robbe, A. Papy - Royal Military Academy, Belgium

  Kinetic energy non-lethal weapons (KE-NLW) are now widely used by law enforcement, by military forces, by the police in situations where the use of lethal arms is not required or suitable. Unfortunately, their effects are still not well known. Therefore, there is a need to better understand the injury mechanism induced by such projectiles for a better prediction of the risk of injury. This may be beneficial for the manufacturer, the deciders or the end-users. Numerical simulations are being increasingly used for that purpose. This paper describes first steps in the development of finite element model for thoracic impacts. All the simulations were performed with Ls-Dyna code. For validation purpose, the results were compared to the results of tests made on Post-Mortem Human Subjects (PMHS) published in literature. The sensitivity of contact option and the use of two sets of parameters for the lung material model were examined.

• Development of a Tool for Automatic Calibration of Material Models in LS-DYNA

  A. Mardalizad ( Polytechnic University of Turin), E. Sadeghipour, M. Lienkamp (Technical University Munich)

  LS-DYNA offers a wide variation of material cards to cover different needs in diverse applications. However, choosing the most proper material model among 250 keywords can be quite deceptive. Therefore, an algorithm has been developed to suggest proper material keywords depending on users’ applications. The algorithm is also coupled with a database of material models to look for proper material cards among the existing ones

• Development of a User-Defined Material Model for Sheet Molding Compounds

  D. Schommer, M. Duhovic, J. Hausmann (Institut für Verbundwerkstoffe), H. Andrae, K. Steiner (Fraunhofer ITWM), M. Schneider (KIT)

  The compression molding of Sheet Molding Compounds (SMCs) is typically thought of as a fluid mechanics problem. The simulation of such materials is at present based on the background of compression or injection molded short fiber reinforced materials. The usage of CF-SMC consisting of high fiber volume content (over 50%) and long fiber reinforcement structures (up to 50 mm) challenges the feasibility of this point of view. The goal of this work is the development of a user-defined material model based on a solid mechanics formulation for SMC materials in LS-DYNA®. To allow for large deformations in the simulation an Arbitrary Lagrangian-Eulerian (ALE) approach is used. As a first step, a material characterization is carried out in a so-called press rheometer test where the mechanical behavior of the SMC material is analyzed during the compression molding process. The resulting stress response of the material then serves as input information for the material model. The material model itself is based on a modular building-block approach. The individual modules describe certain aspects of the material behavior (e.g. compaction, plastic flow behavior or fiber orientation) and interact with one another through the passing of parameters between the respective modules. This procedure allows for the flexible development of the mathematical description for each part of the material behavior. Initially, a simple mathematical model describes every module. In the further development of the model, each module is expanded by more complex mathematical descriptions. As the overall goal is a work in progress, this paper shows the current implementation of several of these modules including the characterized compression and flow behavior as well as a description for the fiber orientation based on the Folgar-Tucker equation. By simulating the press rheometer test itself using the developed user defined material model, a comparison between simulation and experiments is performed to check the accuracy of the various mathematical models used. The stress response and the flow front development provide the basis for the comparison and provide clues on how to proceed with the further development.

• Development of a water filled fender system for off-shore installations

  Sean Duvall - AMEC

  In order to extend the life and productivity of an off-shore oil and gas platform an new installation has been proposed to provide a compression unit. The existing platform is already extensively occupied, having been in existence for over 25 years, and a new approach was required to facilitate the compression unit. This additional facility is an addition outside the existing envelope of the platform and in line with requirements it must withstand a direct ship impact of given mass and velocity. It has been proposed that a fender system be designed that will absorb the energy from the ship impact allowing time to facilitate repair of the platform extension without the need to stop production from the platform. LS-DYNA has been used to model the platform, the proposed extension and the fender system to determine the effects of the ship impact. As with all projects the requirements have changed during the investigation and this paper only represents some of the investigation in to suitability and design of a proposed fender system

• Development of a Wood Material Model For Roadside Safety Applications

  Yvonne D. Murray - Aptek Inc

  A computationally efficient wood material model is being developed and validated for performing LS-DYNA simulations of vehicle collisions into wooden guardrail posts. Typically, the failure modes and stress-strain relationships of wood depend on the direction of the load relative to the grain and the type of load (tension, compression, or shear). The model includes transversely isotropic constitutive equations and yield surfaces to simulate different stiffnesses and strengths parallel and perpendicular to the grain. Hardening and softening formulations simulate stress-strain relationships that are linear to brittle failure in tension and shear, and nonlinear and ductile in compression. A rate effects formulation increases strength with strain rate. For easy use, default material properties for Southern yellow pine and Douglas fir are provided as a function of moisture content, temperature, and grade. Correlations with static bending and bogie impact tests are being used to validate the model.

• Development of Accurate Finite Element Models and Testing Procedures for Bolted Joints in Large Caliber Gun Weapon Systems

  M. Koehler; G. Fish (US Navy)

  Large caliber weapon systems, such as those mounted on tracked vehicles or in turrets on ships, typically develop large forces when fired, which are transmitted to the structure that houses them. In the case of modular weapon systems, often the platform for the weapon system is already developed and the weapon system is integrated at a later stage. In this scenario, it becomes imperative to fully quantify the loads experienced in the bolted connection between the weapon system and the platform in order to ensure a satisfactory fatigue life of the platform. Typically, this is accomplished through the use of finite element analysis in the early stages of development and verified through testing during later stages of development. This work investigates the development of finite element models in LS-DYNA that accurately model bolted joints and compares the tradeoff between efficient models with a coarse mesh and more accurate models with an expensive, fine mesh. Furthermore, these models are validated against an instrumented test specimen in order to determine the accuracy of the finite element models. Throughout this comparison, various sensors are used in multiple locations in order to demonstrate that various conflicting results may be obtained from the same load applied on the joint depending on the type of sensor used and the sensor’s location in the joint.

• Development of Advanced Finite Element Models of Q Child Crash Test Dummies

  Stephen Fu, Christian Kleessen, Zaifei Zhou, Karl Koschdon, Robert Kant - Humanetics

• DEVELOPMENT OF ADVANCED HUMAN MODELS IN THUMS

  Masami Iwamoto, Yuko Nakahira, Atsutaka Tamura, Hideyuki Kimpara, Isao Watanabe, Kazuo Miki - Toyota Central R&D Labs., Inc.

  A finite element model of human body called THUMS has been developed to predict gross motions and multiple skeletal injuries of a whole human body during impacts. Recently, we have developed a head/brain model and thoracic/abdominal internal organ models to evaluate more severe injury risks for occupants and pedestrians in automotive accidents. The head/brain model was validated against some test data on translations and rotations of the head obtained from the literature. The internal organ models were validated against hub impacts for the thorax or abdomen. These models are currently attempted to predict severe injuries in the brain and liver, etc. Finally, we will show THUMS family including a small female, a large male, and a child, etc, which have been developed to investigate the effects of body size on impact responses and injuries.

• Development of Aluminum Honeycomb Model Using Shell Elements

  Shigeki Kojima - Toyota Technical Development Corporation, Japan, Tsuyoshi Yasuki - Toyota Motor Corporation, Japan

  This paper describes a new finite element modeling method of aluminum honeycomb using shell elements. It is our new modeling method that cell size of honeycomb structure is enlarged to keep minimum mesh size, and compressive strength is controlled by thickness of shell elements. New modeling was applied to an offset deformable barrier model, and full vehicle crash analysis was performed. The result of offset frontal collision analysis with a new honeycomb model showed much better correlation with test results than with modified material type-126 solid elements.

• Development of an Airbag Landing System for the Orion Crew Module

  Benjamin Tutt - Airborne Systems, R. Keith Johnson, Karen Lyle - NASA Langley Research Center

  Airborne Systems (formally Irvin Aerospace Inc) has developed an Airbag Landing System design for the Orion Crew Module of the Crew Exploration Vehicle. This work is in support of the NASA Langley Research Center Landing System Advanced Development Project. Orion is part of the Constellation Program to send human explorers back to the moon, and then onwards to Mars and other destinations in the Solar System. A component of the Vision for Space Exploration, Orion is being developed to also enable access to space following the retirement of the Space Shuttle in the next decade. This paper documents the development of a conceptual design, fabrication of prototype assemblies, component level testing and two generations of airbag landing system testing. The airbag system has been designed and analyzed using the transient dynamic finite element code LS-DYNA®. The landing system consists of six airbag assemblies; each assembly contains a primary impact venting airbag and a non-venting anti-bottoming airbag. The anti- bottoming airbag provides ground clearance following the initial impact attenuation sequence. Incorporated into each primary impact airbag is an active vent that allows the entrapped gas to exit the control volume. The size of the vent is tailored to control the flow-rate of the exiting gas. An internal shaping structure is utilized to control the shape of the primary or main airbags prior to ground impact; this significantly improves stroke efficiency and performance.

• Development of an Anisotropic Material Model for the Simulation of Extruded Aluminum under Transient Dynamic Loads

  A. Smith (Honda R&D Americas), P. Du Bois (Consultant), T. Borrvall (DYNAmore Nordic)

  The movement towards lightweight mate rials in the construction of automotive bodies is leading to an increase in parts made from extruded aluminum and other materials with a large degree of anisotropic behavior. The need to model these anisotropic properties and predict the behavior of these materials is increasing rapidly. A review of the anisotropic material models available in LS - Dyna including Material types 36, 133, 135, and 243 led to the decision that Material type 36 with option “Hardening Rule 7“ (HR7) was the most appropriate choice for application towards analysis of extruded aluminum parts under both static and dynamic loads. Material type 36 ( *MAT_3 - Parameter_Barlat ) has a history of use in forming applications and shows promise as a valuable tool for modeling anisotropic behavior in high strain, high velocity simulation applications as well.

• Development of an Energy Absorbing End Terminal for Open Box Beam Guardrail

  Nauman M. Sheikh, Roger P. Bligh, D. Lance Bullard, C. Eugene Buth, Dean C. Alberson, Akram Y. Abu-Odeh, Hayes E. Ross Jr. - Texas Transportation Institute

  An energy absorbing end terminal was developed for use with the European box beam guardrail system. The European box beam rail sections have an open architecture that is different from what is used in North America. The overall design effort utilized finite element simulation, individual component testing using the bogie and pendulum, and performance validation by full scale vehicle crash testing. The design process involved addressing several individual component performance issues. Of these were the design of an extruder head, splice connections for attaching adjacent rail segments, the post to rail attachment connection and anchorage of the rail. The research approach and results are presented in this paper.

• Development of an improved screw model at faurecia

  M. Meyer - Faurecia Autositze

  Some years ago Faurecia used a very simple screw model. In this model the screw holes are filled by a rigid body and the screw shaft is modeld by a simple spring beam with an unrealistic stiffness. But this model doesn’t represent the behavior of screws in real test. With this simple model it was not possible to get the peeling effect of the holes. And the deformation of the part and the screw was unrealistic. Also the forces inside the screw were too high. Due to the goal to reduce the time to market and the number of prototypes to develop a new product it was necessary to develop a better screw model. At the end of 2008 a new keyword was available in LS-Dyna with which it was easy to implement a defined preforce on a beam element. This was the point to start with an improved screw model.

• Development of an LS-DYNA Model of an ATR42-300 Aircraft for Crash Simulation

  Karen E. Jackson, Edwin L. Fasanella - U.S. Army Research Laboratory

  This paper describes the development of an LS-DYNA simulation of a vertical drop test of an ATR42-300 twin- turboprop high-wing commuter-class airplane. A 30-ft/s drop test of this aircraft was performed onto a concrete impact surface at the FAA Technical Center on July 30, 2003. The purpose of the test was to evaluate the structural response of a commuter category aircraft when subjected to a severe, but survivable, impact. The aircraft was configured with crew and passenger seats, anthropomorphic test dummies, forward and aft luggage, instrumentation, and other ballast. The wings were filled with approximately 8,700 lb. of water to represent the fuel and the aircraft weighed a total of 33,200 lb. The model, which consisted of 57,643 nodes and 62,979 elements, was developed from direct measurements of the airframe geometry. The seats, dummies, luggage, fuel, and other ballast were represented using concentrated masses. Comparisons were made of the structural deformation and failure behavior of the airframe, as well as selected acceleration time history responses.

• Development of BioRID II Dummy Model using Stochastic Methods

  Sebastian Stahlschmidt, Bastian Keding, Katharina Witowski, Heiner Müllerschön, Uli Franz - DYNAmore GmbH, Stuttgart, Germany

  Consumer and insurance organizations use the BioRID II dummy as test device to assess the risk of whiplash injuries in rear crash scenarios. DYNAmore GmbH developed a finite element model for LS-DYNA of the BioRID II dummy in cooperation with the German Automotive Industry (FAT). The project follows the updated development guidelines of successfully developed models for the FAT in previous projects. This paper describes the applied development methodology, modeling techniques and the current model. Due to significant pre-stress in the dummy and other new features the modeling requires LS-DYNA 971. An outline of the good performance of the model release 2.0 in various validation tests is presented. The paper concludes with results from robustness investigations performed with LS-OPT.

• Development of BioRID-II Dummy Model in Cooperation with the German Automotive Industry

  Peter Schuster, Sebastian Stahlschmidt, Uli Franz - DYNAmore GmbH

• Development of Carbon Fibre Floor Structure for Premium Electric SUV

  P. Bristo (NIO)

  NIO are a global automotive startup producing electric vehicles for the China market. Our second vehicle, the ES6, was unveiled in December 2018 in Shanghai. It features a lightweight carbon fibre floor body structure, which will become the first high volume CFRP production part in ASIA. This presentation describes the CAE activities undertaken to develop the composite body structure. It explains the approach that was taken to construct the DYNA material cards and the various material tests used to validate them. It explores the various CAE activities used to develop and optimise the design of the parts and the layups of composite layers, and then the successful validation of the parts.

• Development of Detailed AF05%ile Hybrid III Dummy FE Model

  Yoichiro Ohnishi, Mariko Mohri, Hayato Kaneko, Tatsuya Komamura, Tsuyoshi Yasuki

  This paper describes a development of the Hybrid III AF05%ile dummy FE model to be used for frontal crash simulations. The precise geometries of the dummy were measured at a pitch of 1.0 mm using X-ray CT scans. The material properties and the mechanical responses of the components were measured in static and dynamic tests and were used for the model validation. The FE model results showed a good correlation with the kinematics and injury index values to those in the sled impact test.

• Development of Dynamic Punch test with DIC for Verification of Simulations with MAT224

  Amos Gilat, Jeremy D. Seidt, Jeremiah T. Hammer, and Timothy J. Liutkus (Ohio State University, USA)

  Calibration and verification of simulations with LS-DYNA® in which plasticity and failure models, like MAT224, are used require data from well controlled experiments. One example is the simulation of containment during blade-off and disk failure in jet engines. This application requires accurate simulation of the penetration of a projectile at many combinations of impact speeds, projectile-target geometries, and temperatures. To validate the simulations of this application, a new dynamic punch test has been developed. In this test, shown schematically in the figure below, a round disk specimen is attached to the transmitter bar of a compression Split Hopkinson Bar (SHB) apparatus, and a punch is attached to the incident bar of the SHB apparatus. During a test, a compression wave is introduced into the incident bar which causes the punch to penetrate into the specimen. The full-field deformation of the back surface of the specimen is measured during the test by using the Digital Image Correlation (DIC) technique. This is possible because the specimen is supported by a slotted tubular adaptor that provides a stereographic view of the deforming back surface. The force measured in the transmitter bar of the SHB apparatus corresponds to the contact force between the punch and the specimen. Various states of stresses and different penetration modes (petaling, bending, plugging) can be obtained by changing the specimen thickness and punch geometry. Results from tests with specimens made of Ti-6Al-4V with punches of various geometries show that the punch geometry greatly influences the punching force and the failure mode. The 3D DIC and the force measurements provide data that can be used to construct and validate deformation failure models.

• Development of Effective Taylor-Quinney Coefficient Table of *MAT_224 for Aluminum 2024-T351

  Chung-Kyu Park, Kelly Carney, Paul Du Bois, Cing-Dao Kan

  In this research work, the effective Taylor-Quinney Coefficient (TQC) table of *MAT_224 for Aluminum 2024-T351 alloy was developed to replace the current constant TQC. The methodology to create the effective TQC table was developed by using a two-step approach. In Step 1, the thermal-structural analyses of tensile tests were conducted to verify the referenced TQC values and generate the additional temperature-strain curves at additional rates which were not covered by the physical tensile tests. In Step 2, the structural-only analyses of tensile tests were conducted to calibrate the effective TQC values at all the rates for the effective TQC table and validate the calibrated effective TQC table.

• Development of Far-Side Sled Simulation Model with Airbag for Virtual Testing

  Hisaki Sugaya, Yu Kanayama, Kanae Matama, Nanami Kobayashi, Takashi Kikuchi

  Currently, Euro NCAP announced a virtual test to improve safety performance robustness. Starting with the Far-side sled test, robustness will be evaluated at different angles and seat positions. Since robustness is evaluated only by simulation, it is crucial to improve the accuracy of the model. Therefore, the objective of this study is to verify the model accuracy level by comparing the simulation with the far-side SLED test with airbag as a benchmark for the virtual test.

• Development of Finite Element Models of Restraint System for Injury Analysis in Side Impact

  Satoshi Fukushima, Koushi Kumagai, Tsuyoshi Yasuki - Toyota Motor Corporation, Yoshiharu Sonoda, Yu Setoyama - Toyota Technical Development Corporation

  The use of occupant protection simulation by finite element model is increasing for vehicle development. Finite element models of moving deformable barrier honeycomb, vehicle body, dummy, and restraint system have been developed to predict the dummy injury values. To more accurately predict the dummy injury indices in side impact analysis, this paper describes the improvement of finite element models of restraint system such as torso airbag and polyurethane pad. The improved model of polyurethane pad was able to simulate both of anisotropy and breaking. The improved model of torso airbag was able to simulate the deployment behavior from inside of seat back foam. Finally, full vehicle level FE analysis was conducted to confirm the prediction accuracy of the dummy injury indices using the improved finite element models. The results show that the dummy injury indices correlate well with actual crash testing.

• Development of Frequency Domain Dynamic and Acoustic Capabilities in LS-DYNA

  Yun Huang, Mhamed Souli, Cleve Ashcraft, Roger Grimes, Jason Wang - Livermore Software Technology Corporation, Mostafa Rassaian, Jung-Chuan Lee - The Boeing Company

  A set of new features for frequency domain dynamic and acoustic computation have been implemented in LS- ® DYNA . They include random vibration and high-cycle fatigue analysis, frequency response functions, steady state dynamics, response spectrum analysis, and acoustic analysis based on boundary element methods or finite element ® methods. The objective of introducing these new features is to add capabilities to LS-DYNA to solve frequency domain vibration and noise radiation problems. This class of problems is very common in auto and aerospace industries and many other industries. The paper provides a brief introduction of the new features. Keywords for the features are introduced. Areas of applications are discussed. Some examples are given to illustrate how to use these features.

• Development of Hail Material Model for High Speed Impacts on Aircraft Engine

  Yann CHUZEL,Alain COMBESCURE - LaMCoS INSA Lyon, Marco NUCCI, Yann PERRIN - Snecma Villaroche, Roland ORTIZ - Onera Lille

  Hail impacts represent a threat for aircrafts and their engines. As experimental tests on aircraft engines are expensive and they can not be done in early stages of the development, numerical simulations to predict hailstone impacts on engine blades have to be developed. The purpose of this work is to present a new material model for simulating hailstone impacts on engine blades. Aeronautical industry has already developed numerical models for similar problems of bird impacts using LS- DYNA®. They simulate the bird using SPH particles to predict projectile failure and Lagrangian solid elements for the blade.. In order to simulate hail impact, numerical model for bird strike is used and projectile material is replaced by a new material model. Experimental results show hail has a brittle behavior which is similar to concrete’s, so mechanical behavior may be simulated by an elastic damage model based on Mazars’ law used for concrete. Damage Mazars’ model is improved by adding traction and compression damage and a delay effect is added in order to reduce mesh dependence. This hail law is developed in LS-DYNA code through a user defined material (UMAT), tested on simple cases of plate impact and used for impacts on the aircraft engine blade. This paper presents the existing LS-DYNA models simulating hail impact and their limits and describes hail tests used to study the material law and to develop the numerical model. Validation tests are presented to show out the behavior of hail, effects of model parameters, and the role of delay effect. Hailstone impact tests on an aluminum plate carried out by British Royal Aircraft Establishment (RAE) and Office national d'études et de recherches aérospatiales (ONERA) are used in order to identify the model. An impact on a blade is then simulated with the identified model and is compared with Snecma’s test.

• Development of LSTC WorldSID Dummy Finite Element Model (50th Percentile Male)

  Fadi Tahan, Dhafer Marzougui, Cing-Dao Kan, Center for Collision Safety and Analysis, George Mason University;, Umashankar Mahadevaiah, Consultant;, Christoph Maurath, Livermore Software Technology Corporation

  A finite element model in LS-DYNA® of the WorldSID 50th Percentile Male Dummy has been developed by the Center for Collision Safety and Analysis at George Mason University (CCSA – GMU) in collaboration with Livermore Software Technology Corporation (LSTC). The dummy parts have been meshed and were assembled based on the dummy 2-D and 3-D drawings that the World Side Impact Dummy (WorldSID) Task Group designed and approved under the direction of the International Organization for Standardization (ISO), Road Vehicles technical committee (ISO/TC22/SC12/WG5).

• Development of Material Input Data for Solid Elements under Crash Loads

  Dr. Ing. Harald Mandel - BA-Stuttgart, Paul Du Bois -, Tim Rzesnitzek - Daimler AG, Stuttgart Germany

  Heavy trucks have large masses and only small deformation zones. Because of this, they are loaded relatively severe in case of a crash. Under those conditions structural response is characterised not only by plastic deformation but also by failure in terms of cracks or fracture. Hence, failure prediction is essential for designing such parts. The following article describes the procedure of generating material models for failure prognosis of solid parts in the Commercial Vehicles Division at Daimler. Sheet metal parts are mostly discretised by shell elements. In this case the state of stress is characterized by hydrostatic pressure over von-Mises effective stress, the so-called triaxiality. For many real-life load cases which can be modeled by thin shells this ratio is between –2/3 and –2/3. Within this range the Gurson material model with the Tvergaard Needlemann addition leads to sufficiently accurate results. Furthermore, the Gurson material model allows considering the effect of element size, which amongst others is important for ductile materials. Most often however, in the case of solid parts the state of stress is more complex, which results in a triaxiality smaller than –1 or larger than 2/3. Gurson material models are usually validated based on shell meshes and tensile tests with flat bar specimen. If applied to solid parts, these models tend to underpredict failure . Thus, for solid parts the GURSON_JC material model is used. The Johnson Cook parameters are derived from an existing Gurson material model. Afterwards the material model is adapted to test results by modifying the load curve giving failure strain against triaxiality. This requires tensile tests with grooved and non-grooved round bars, shear tests and validation tests on actual parts.

• Development of Material Input Data for Solid Elements under Crash Loads

  Dr. Ing. Harald Mandel - BA-Stuttgart, Paul Du Bois -, Tim Rzesnitzek - Daimler AG, Stuttgart Germany

  Heavy trucks have large masses and only small deformation zones. Because of this, they are loaded relatively severe in case of a crash. Under those conditions structural response is characterised not only by plastic deformation but also by failure in terms of cracks or fracture. Hence, failure prediction is essential for designing such parts. The following article describes the procedure of generating material models for failure prognosis of solid parts in the Commercial Vehicles Division at Daimler. Sheet metal parts are mostly discretised by shell elements. In this case the state of stress is characterized by hydrostatic pressure over von-Mises effective stress, the so-called triaxiality. For many real-life load cases which can be modeled by thin shells this ratio is between –2/3 and –2/3. Within this range the Gurson material model with the Tvergaard Needlemann addition leads to sufficiently accurate results. Furthermore, the Gurson material model allows considering the effect of element size, which amongst others is important for ductile materials. Most often however, in the case of solid parts the state of stress is more complex, which results in a triaxiality smaller than –1 or larger than 2/3. Gurson material models are usually validated based on shell meshes and tensile tests with flat bar specimen. If applied to solid parts, these models tend to underpredict failure . Thus, for solid parts the GURSON_JC material model is used. The Johnson Cook parameters are derived from an existing Gurson material model. Afterwards the material model is adapted to test results by modifying the load curve giving failure strain against triaxiality. This requires tensile tests with grooved and non-grooved round bars, shear tests and validation tests on actual parts.

• Development of New Simulation Technology for Compression Molding of Long Fiber Reinforced Plastics using LS-DYNA®

  Shinya Hayashi1, JSOL Corporation, 2-18-25 Marunouchi, Naka-ku, Nagoya, Aichi, 460-0002, Japan;, Hao Chen, Wei Hu, Livermore Software Technology Corporation, 7374 Las Positas Road, Livermore, Ca 94551, USA

  Composite materials like fiber reinforced plastics (FRP) are becoming more widely used in the automotive industry and have been found very effective in reducing vehicle weight. Recently, long carbon fiber reinforced thermoplastics are increasingly being used for lightweight structural parts with high stiffness, strength and energy absorption performance. Compression molding is considered one of the most efficient manufacturing processes to mass produce FRP parts for automotive applications. Compression molding can form long fiber reinforced thermoplastics into complex shapes with relatively low manufacturing cost and short process time. In this paper, a new simulation technology for compression molding of long fiber reinforced plastics implemented in LS-DYNA is presented.

• Development of numerical models for the investigation of motorcyclists accidents

  Mazdak Ghajari, Lorenzo Iannucci - Imperial College London, Caroline Deck, Remy Willinger - Strasbourg University, Ugo Galvanetto - Padova University

  The Finite Element (FE) method was employed to develop and enhance numerical models that can be used for simulating accidents involving motorcyclists. They are the FE models of a commercial helmet, the human head and the Hybrid III dummy. The composite shell and foam liner of the helmet, which are the most important components in terms of energy absorption, were generated using the Ls-Dyna preprocessing software. The FE model of the human head, which was developed in the Radioss environment, was converted to the Ls-Dyna format. In order to validate the head model with respect to the skull force-deflection response and intracranial pressures, two cadaveric tests reported in literature were simulated. The model of the head was coupled, through the neck, with the body of the Hybrid III dummy. This new dummy was capable of predicting the skull fracture as well as intracranial injuries such as the diffuse axonal injury. As an application of the models, the Hybrid III dummy and the new dummy were equipped with the helmet and dropped onto a flat anvil at the 7.5 m/s impact speed. The protective capability of the helmet was assessed with respect to kinematic injury predictors, such as the maximum linear acceleration of the head, and tissue level injury predictors, such as Von Mises stress in the brain.

• Development of numerical models for the investigation of motorcyclists accidents

  Mazdak Ghajari, Lorenzo Iannucci - Imperial College London, Caroline Deck, Remy Willinger - Strasbourg University, Ugo Galvanetto - Padova University

  The Finite Element (FE) method was employed to develop and enhance numerical models that can be used for simulating accidents involving motorcyclists. They are the FE models of a commercial helmet, the human head and the Hybrid III dummy. The composite shell and foam liner of the helmet, which are the most important components in terms of energy absorption, were generated using the Ls-Dyna preprocessing software. The FE model of the human head, which was developed in the Radioss environment, was converted to the Ls-Dyna format. In order to validate the head model with respect to the skull force-deflection response and intracranial pressures, two cadaveric tests reported in literature were simulated. The model of the head was coupled, through the neck, with the body of the Hybrid III dummy. This new dummy was capable of predicting the skull fracture as well as intracranial injuries such as the diffuse axonal injury. As an application of the models, the Hybrid III dummy and the new dummy were equipped with the helmet and dropped onto a flat anvil at the 7.5 m/s impact speed. The protective capability of the helmet was assessed with respect to kinematic injury predictors, such as the maximum linear acceleration of the head, and tissue level injury predictors, such as Von Mises stress in the brain.

• Development of Orbital Debris Impact Protection Panels

  M. ANGHILERI, L. CASTELLETTI, F. INVERNIZZI, M. MASCHERONI, F. PIGOLI - Politecnico di Milano, Italia

  The presence of debris in the orbits used by artificial satellites represents an actual threat for space operations – as such an event is likely to cause the failure of the satellite. Spacecraft hulls are in general built with honeycomb-cored sandwich panels made of Aluminium alloys - which are not effective as a protection in case of medium size debris impact. Using LS-Dyna 970, the benefits (from a mechanical standpoint) coming from the use of materials such as polymeric foams or aramidic fibres in manufacturing hull panels were investigated. Indeed, these materials are frequently used in common applications for their excellent ballistic characteristics and low weight. Initially, a reliable numerical model was developed referring to experimental tests consisting of the impact of medium size debris against sandwich panels with honeycomb core. Hence, using the same impact scenario of the tests, the impact behaviour of different panel typologies obtained using a polymeric foam core or using aramidic fibres as reinforcement was evaluated. As a result, it was possible to highlight the advantages coming from the use of these materials in order to have lightweight and debris-proof structures.

• Development of Parachute Simulation Techniques in LS-DYNA

  Benjamin Tutt, Scott Roland - Airborne Systems, Richard Charles, Greg Noetscher - Natick Soldier Center

  Parachute design often relies heavily on historical experimental data, and parachute development frequently requires numerous test campaigns. Although both of these techniques eventually result in successful parachute systems, such an approach will rarely result in any true advance to parachute engineering knowledge. Consequently, an unusually high emphasis is placed on experienced parachute design personnel, and often similar lessons have to be re-learnt over and again. Airborne Systems has been at the forefront of parachute modeling using Fluid Structure Interaction (FSI) techniques for the past 7 years. Significant advances have been made in parachute modeling using this powerful technology, many of which have been a direct result of US Army Natick Soldier Research, Development and Engineering Center funding and support. This paper presents the current "state of the art" parachute modeling at Airborne Systems using LS-DYNA. It discusses recent advances in simulating parachute performance and areas of future study. It documents fabric material modeling, wind tunnel class parachute analysis, parachute inflation studies, and comparisons with drop test data. A description of the modeling methodology is included as well as the application of the technology in a number of real world parachute applications including the old T-10 and the new T-11 US Army mass tactical assault parachutes.

• Development of Pedestrian Headform Finite Element (FE)Model using LS-DYNA® and its validation as per AIS 100/GTR 9

  N. A. Kulkarni, S. R. Deshpande, R. S. Mahajan (The Automotive Research Association of India)

  Thousands of pedestrians die due to road accidents in the world every year. Head injury is more life threatening and most common cause of pedestrian deaths in pedestrian to vehicle collision. To reduce rate of pedestrian death, international safety committees have developed test in which headform impactors are impacted upon car vehicle front structure (bonnet) and approval is given based on headform acceleration within specified range.

• Development of Pedestrian Protection for the Qoros 3 Sedan

  Niclas Brannberg, Pere Fonts, Chenhui Huang, Andy Piper, Roger Malkusson (Qoros Automotive Co., Ltd)

  Pedestrian protection has become an important part of the Euro NCAP consumer test and to achieve a 5-star rating for crash safety, a good rating for the different pedestrian load cases is imperative. It was decided at the very start of the Qoros 3 Sedan’s development program that this should be made a priority. A skilled team of safety engineers defined the layout of the vehicle to support this target, and an extensive simulation program using LS-DYNA was planned to define and validate the design intent without compromising the design of the vehicle as well as maintaining all other important vehicle functions. This paper will provide an insight into part of the journey taken to establish a new vehicle brand in China, fulfilling high European safety standards at an affordable cost, and how Qoros succeeded in this mission with a combination of skills, extensive CAE analysis and finally the validation of the recipe during physical testing. The paper will highlight how the high rating for pedestrian protection was obtained and give a short overview of the complete safety development of the Qoros 3 Sedan.

• Development of Researched Moving Deformable Barrier (RMDB) FE model for Oblique Crash Test

  Nobuhisa Ishiyama, Shinobu Tanaka, Satoshi Fukushima, Tsuyoshi Yasuki (Toyota Motor Corporation), Masahiro Saito (Toyota Technical Development Corporation), Jesse Buehler, Brian Tew (Toyota Motor Engineering & Manufacturing North America)

  This paper describes a finite element model for a Researched Moving Deformable Barrier (RMDB) that simulates an oblique crash test. National Highway Traffic Safety (NHTSA) is currently conducting research on oblique RMDB-to-Vehicle (Oblique) testing. The RMDB, which consists of an aluminum honeycomb and an outer cladding sheet, exhibited two deformation features after the oblique crash test. The first was cracks observed on the outer cladding sheet. The second was compressive deformation, mainly observed on the 0.724MPa aluminum honeycomb. The RMDB FE model was developed based on the SAE paper. The aluminum honeycomb had two layers with different stiffness and was modeled by shell element to capture compressive deformation. The outer cladding sheet was modeled by tied overlapping shell elements, in order to simulate crack propagation. The RMDB FE model was validated through the impactor test and the full car test. The results of the analyses using the model closely matched to the test results. The impactor model was developed to conduct impactor component testing. The aluminum honeycomb was glued to the jig and the impactor crashed into the aluminum honeycomb. The resulting fracture line on the outer cladding sheet and impactor acceleration data was correlated to test. Next, full car testing was performed refer to the SAE paper. The RMDB and car kinematics, velocity, structure deformation, and body intrusions largely matched to those from test. Cracks, generally corresponding to those in the test, were observed from analysis result in the outer cladding sheet. The aluminum honeycomb compressive deformation was also close to the test deformation result. Investigation of the effects of crack propagation in the outer cladding sheet revealed that deformation in the upper aluminum honeycomb showed difference depending on whether the outer cladding sheet had cracks ore not. Thus, reproducing the outer cladding sheet cracks is effective in simulating RMDB deformation.

• Development of Shipping Package Drop Analysis Capability at Westinghouse

  J. F. Staples - Westinghouse Electric Company LLC1, M. Pitzer, P. A. DuBois - Hermes Engineering

  Westinghouse Electric Company LLC1 is currently developing a new shipping package for transporting nuclear fuel to customer sites. This new design is designated as the TravellerTM shipping package.2 One of the many licensing requirements for the Traveller package is to demonstrate it will always maintain the fuel assembly in a (nuclear) non-critical configuration after being dropped from 9 meters onto an unyielding surface and from 1 meter onto a 15 mm diameter pin. In meeting these regulations, package orientation(s) which will most damage: 1. the fuel assembly; and, 2. the shipping package must be considered. Westinghouse began the Traveller design effort with a need to supplement in-house analytical capability with experienced LS-DYNA consultants. However, the Traveller analysis was not simply “handed off.” Rather, a Westinghouse analyst worked closely with these consultants. This close interaction resulted in a shipping package model which included all features relevant to crashworthiness and correctly represented the final design. The resulting model was instrumental in the success of the drop tests and licensing efforts.

• Development of Simple Connection Model for Plastic Parts in Low-Speed Crash Simulation

  N. Matsuura, Y. Nakagawa, O. Ito, K. Kaneda, Y. Ueda (Honda R&D)

  Collision performance is evaluated by CAE not only for metal parts such as steel and aluminum but also for plastic parts. As it takes time to create molds for a large part such as the bumper face, ensuring the performance by pre-calculation is important to shorten the development period. When mold production is started prior to the test to reduce the development time and if failures occur in the test, it will take time and cost to modify the mold. Therefore, high calculation accuracy is desired, but the test reproducibility is not satisfactory in some areas. Out of those areas undergoing enhancement efforts, this document introduces our efforts for plastic parts connection coming-off.

• Development of Simplified Truck Chassis Model for Crashworthiness Analysis

  Yucheng Liu, M. L. Day - University of Louisville, USA

  In this paper bending resistance of thin-walled channel beam is applied to create simplified model for truck chassis. In the simplified model, beam and nonlinear spring elements are used to model the side-rails, and equivalent beams are applied to represent the cross members. Both detailed and simplified models are used for crashworthiness analyses, and the results are recorded and compared. Relatively good agreement is achieved between these analyses, while the computing time is significantly reduced for the presented modeling method.

• Development of special new versions of the FAT/PDB Dummy models for quick analysis response. The Rapid Analysis Models (R.A.M.)

  Reuben D’Souza, Yupeng Huang, Sebastian Stahlschmidt (DYNAmore GmbH, Germany)

  The finite element model of the FAT and PDB Dummy models have been developed in co-operation with the German Automotive lndustry for the last few years, One of the major goals during the development of the models was to achieve a high degree of accuracy of the model as well as to have a robust model without numerical instabilities. During the course of the model development, the geometry of various components has evolved considerably and finite element meshes for the various components have gotten finer. New material tests were also carried out for many components resulting in the use of advanced material models. This has naturally resulted in an increase in the computation times for the model. Increased computation times are definitely a hindrance when it comes to carrying out a studywith a large sample set for example. Keeping this in mind, we at DYNAmore have developed a simplified version of the ES-2IES-2re model meant for rapid prototming. This simplified model requires considerably lesser computation time and delivers extremely good results in the component and barrier tests, considering the degree of simplicity of the model. The geometry of the model has remained unchanged. Simplified and "quicker" materid models have been used wherever possible and all the certification and component tests were carried out for the model. Development of a R.A.M. model of the WorldSID 500b has also been started. As a final step, the soffware CORA [1J (CORrelation and Analysis) waas used to obtain an objective comparison of the simplified model to the original model.

• DEVELOPMENT OF THE DYNA3D SIMULATION CODE WITH AUTOMATED FRACTURE PROCEDURE FOR BRICK ELEMENTS

  Ala Tabiei, Jin Wu - University of Cincinnati

  Numerical simulation of cracked structures is an important aspect in structural safety assessment. In recent years, there has been an increasing rate of development of numerical codes for modeling fracture procedure. The subject of this investigation is implementing automated fracture models in the DYNA3D nonlinear explicit finite element code to simulate pseudo 3-D crack growth procedure. The implemented models have the capabilities of simulating automatic crack propagation without user intervention. The implementation is carried on solid elements. The methodology of implementing fracture models is described. An element deletion-and- replacement remeshing procedure is proposed for updating the explicit geometric description of evolving cracks. Fracture parameters such as stress intensity factors, energy release rates and crack tip opening angle are evaluated. The maximum circumferential stress criterion is utilized to predict the direction of crack advancement. Seven crack problems are presented to verify the effectiveness of the methodology. Mesh sensitivity and loading rate effects are studied in the validation of the presented procedure.

• Development of the PDB WorldSID 50th Model with the German Automotive Industry

  A. Gromer, S. Stahlschmidt, R. D'Souza - DYNAmore

  In times where simulation methods are well-established in Vehicle Passive Safety Development, it is indispensable to provide a virtual equivalent of current hardware dummies. Thus, German car manufacturers decided to build up a WSID50th finite element model. Due to the experience of former FAT dummy development projects, the processing of the WSID50th model achieves a high efficiency level. The project started with building up a model using the material data of other dummy projects - release version 0. After an immense number of material and component tests the WSID50th model validation level is increased and qualifies the model for production - release version 1. This paper describes the evolution and features of version 1 in detail. There is a detailed description of the individual component test validation and its results.

• Development of the PDB WorldSID 50th Model with the German Automotive Industry

  A. Gromer, S. Stahlschmidt, R. D'Souza - DYNAmore

  In times where simulation methods are well-established in Vehicle Passive Safety Development, it is indispensable to provide a virtual equivalent of current hardware dummies. Thus, German car manufacturers decided to build up a WSID50th finite element model. Due to the experience of former FAT dummy development projects, the processing of the WSID50th model achieves a high efficiency level. The project started with building up a model using the material data of other dummy projects - release version 0. After an immense number of material and component tests the WSID50th model validation level is increased and qualifies the model for production - release version 1. This paper describes the evolution and features of version 1 in detail. There is a detailed description of the individual component test validation and its results.

• Development of Tied Overlapping Shell Technique to Simulate the Path of Crack Propagation in Polymer Parts

  S. Kojima, K. Ishibashi (Toyota Tech. Dev. Corp.), T. Yasuki, H. Arimoto (Toyota Motor Corp.)

  This paper describes a new finite element modeling technique to simulate the path of crack propagation in polymer parts. In this new technique "tied overlapping shell technique", base and overlapping elements make up the finite element model surface. The overlapping elements are rotated 45 degrees with respect to the base elements and are connected by tied contact. Tied overlapping shell technique decreased mesh pattern dependency of FE crack propagation. Tied overlapping shell technique was applied to a polymer door trim model, and impactor crash FE analysis was performed. The result of the FE crack propagation path with the new technique correlated with the experimental result.

• Development of validated Finite element model of an articulated truck suitable to simulate collisions against road safety barriers

  M. Pernetti - Second University of Naples, S. Scalera, G. Cibllis - University of Naples "Federico II"

  Crashworthiness is one of the most important aspect which is taken into account in road design. The effectiveness of Finite Element Method (FEM) to solve major design problems and as a tool to perform parametric studies, has been plainly demonstrated in literature. Of course this is possible only when available models of vehicles and devices are calibrated in a wide range of impact conditions. This research, was intended to develop a well defined multipurpose finite element model of an articulated truck. The model has been set up taking into account two real test impacts, the first against a concrete wall and the second against a steel bridge safety barrier. The fundamental steps of the modelling process will be described along with any requirements needed to reproduce the two full scale tests. The results obtained demonstrate that the modelling processes of vehicle and safety devices were accurate and that, in particular, the articulated truck FE model is suitable for a wide range of impact conditions. As a conclusion, the validated model is reliable to foresee the impact behaviour without needing expensive crash tests.

• Development of validated Finite element model of a rigid truck suitable to simulate collisions against road safety barriers

  M. Pernetti - Second University of Naples, S. Scalera - University of Naples "Federico II"

  The effectiveness of FEM (Finite Element Method) to improve the crashworthiness, both of the vehicle and of the road safety hardware, has been plainly demonstrated in literature. As well known, such a methodology can be successfully employed (i) as a support to design novel devices and (ii) as a tool to perform parametric studies to assess the influence of different factors. Of course this is possible only when available models are calibrated in a wide range of impact conditions. In this work, a well detailed finite element model of a rigid truck is presented. The model has been validated through an extensive comparison with two full scale impact tests, the first against a concrete wall and the second against a road safety steel barrier. The excellent agreement attained when simulating the abovementioned impacts, characterized by noticeably different nature, demonstrates that the modelling processes of the vehicle and devices were accurate and that, in particular, the FE model of the Heavy Good Vehicle is suitable for a wide range of impact conditions. As a conclusion, the validated model is reliable to predict the impact behaviour without needing expensive crash tests.

• Development, implementation and Validation of 3-D Failure Model for Aluminium 2024 for High Speed Impact Applications

  Paul Du Bois, Murat Buyuk, Jeanne He, Steve Kan - NCAC-GWU

  FAA William J Hughes Technical Center (NJ) conducts a research project to simulate failure in aeroengines and fuselages, main purpose is blade-out containment studies material testing performed by OSU ballistic testing performed by NASA/GRC numerical simulations performed by GWU-NCAC involved the implementation in LS-DYNA of a tabulated generalisation of the Johnson-Cook material law with regularisation to accommodate simulation of ductile materials previously published results in : A Generalized, Three Dimensional Definition, Description and Derived Limits of the Triaxial Failure of Metals, Carney, DuBois, Buyuk, Kan, Earth&Sky, march 2008

• Development, Optimization, and Design for Robustness of a Novel FMVSS 201U Energy Absorber

  David M. Fox - US Army Tank Automotive Research, Warren, MI

  In order to streamline the product development process, the design space for FMVSS 201U impact performance of a steel mechanical energy absorber assembly was investigated by means of LS-DYNA 970 explicit finite element simulation methods in conjunction with statistical analytical procedures. A sequence of response surfaces, based on various levels of design parameters, was developed and used to determine minimal stopping distance for which it would be possible to achieve acceptable impact attenuation performance under various impact loading conditions given a worst case assumption of rigid vehicle interior body panels. A model was also developed, based on the variation of deterministic variables, in order to estimate and minimize, by means of a robustness analysis, the range of deviation of product response that would be expected as a result of variability in manufacturing and installation processes.

• Developments in *MAT_WINFRITH_CONCRETE and Application to Modelling of Segmented Concrete Tunnel Linings

  Richard Sturt, Gianmarco Montalbini, Hyuk-Il Jung, Marc Tatarsky

  Tunnels constructed by Tunnel Boring Machines are lined with precast reinforced concrete segments. The joints between the segments must resist a combination of compressive load and bending moments induced by non-uniform pressure from the soil. Failure modes to be considered during design include splitting of the joint face under concentrated compressive load, spalling of the exterior or interior faces of the segments under bending actions, and impacts of bolt connection details on the stability of the joints. The capacity of the segments to resist such failures may be explored in detail using LS-DYNA’s nonlinear concrete models. The paper includes examples from an investigation into a tunnel that partially collapsed shortly after construction. The failure modes revealed by the site investigation of the collapsed tunnel matched well with those shown by the model.

• Developments in Finite Element Safety Models

  J. Rasico - FTSS

  FTSS has been providing Finite Element models to the safety community for over a decade. This has resulted in an expansive family of; commonly used Anthropomorphic Test Devices (ATDs), dummies primed for future regulation, and complimentary safety tools for the examination of unique protection systems, such as ejection mitigation. In conjunction, the last 10 years have seen a continuous demand for increased quality and functionality of existing dummy model products, and new tools to help safety engineers address the evolving requirements of regulatory bodies and consumer agencies. While an expanding database for development and validation has helped dummy models reach further levels of maturity and accuracy, close involvement with physical product design and development has allowed for early adaptation of hardware updates. Furthermore, collaborative efforts within the automotive community have become a key component of new model development. With this approach, these new models target the upfront requirements of OEMs and their suppliers. Further improvement of existing models and end-user participation for the development of new models is leading to more powerful ready-to-use models for safety engineers in the Finite Element community.

• Developments in Finite Element Safety Models

  J. Rasico - FTSS

  FTSS has been providing Finite Element models to the safety community for over a decade. This has resulted in an expansive family of; commonly used Anthropomorphic Test Devices (ATDs), dummies primed for future regulation, and complimentary safety tools for the examination of unique protection systems, such as ejection mitigation. In conjunction, the last 10 years have seen a continuous demand for increased quality and functionality of existing dummy model products, and new tools to help safety engineers address the evolving requirements of regulatory bodies and consumer agencies. While an expanding database for development and validation has helped dummy models reach further levels of maturity and accuracy, close involvement with physical product design and development has allowed for early adaptation of hardware updates. Furthermore, collaborative efforts within the automotive community have become a key component of new model development. With this approach, these new models target the upfront requirements of OEMs and their suppliers. Further improvement of existing models and end-user participation for the development of new models is leading to more powerful ready-to-use models for safety engineers in the Finite Element community.

• Developments in Line-Die Simulation and Exterior Surface Quality Check

  Klaus Wiegand - Daimler AG, Li Zhang, Xinhai Zhu - Livermore Software Technology Corporation

  A review of recent developments in stamping manufacturing will be conducted. The review will be focused in area surrounding the new line die simulation capabilities and in exterior surface panel quality check.

• Developments in LS-DYNA for Metal Forming Simulations

  X. Zhu, L. Zhang (LSTC)

  One - step simulation with keyword *CONTROL_FORMING_ONESTEP has been widely in use in crash and safety for forming stress and strain initialization. It has also being used for initial estimating of blank size in stamping application. One problem stamping users face is the position of the blank after unfolding can be undesirable. Also, the shifted unfolded blank is not easy to align relative to the tooling position.

• Developments in Occupant and Seat Modelling with Primer 9.3

  Miles Thornton, Richard Sturt, Chris Bell - Arup

  There is constant pressure to reduce the time needed to process design data into crash results (mesh, assemble, create different crash cases, check, run, post-process). The meshing step has been reduced by batch meshing technology, and progress has been made in several other areas such as automatic post-processing. Attention is now turning to the remaining bottlenecks, which include occupant and seat positioning. These steps require careful manual work and cannot currently be automated. The problem is magnified by the large number of seat position/dummy combinations. • It is intended that Primer Version 9.3 will solve these problems, by providing fast methods of dummy positioning, seat positioning, seat foam compression, and belt fitting.

• DEVELOPMENTS IN THE APPLICATION OF LS-DYNA TO FLUID STRUCTURE INTERACTION (FSI) PROBLEMS IN RECOVERY SYSTEM DESIGN AND ANALYSIS

  Anthony P. Taylor - Irvin Aerospace Inc.

  Irvin Aerospace Inc. has used the LS-DYNA Explicit Finite Element Analysis (FEA) tool for over five years for that analysis of static and dynamic fabric problems. The references provide many examples of this previous work. Our first application was the analysis of airbag landings for several spacecraft programs, including Reusable Launch Vehicles (RLV’s), various Unmanned Air Vehicles (UAV’s), Military Airdrop Systems, and planetary exploration systems. These programs are thoroughly covered in the references, including comparisons between simulation and test. Our database of test to simulation comparisons and understanding model details where simulation does or does not apply continues to grow. Additional static and dynamic simulations include various pressurized fabric beams and fabric impact analysis; these are also covered in the references, including another paper presented at this conference. In the past year, Irvin has begun to explore the FSI capability within LS-DYNA through the explicit Navier-Stokes solver, the ALE solutions technique, and the various coupling options. This capability begins to provide Irvin with a capability, which in our industry is currently only available in Government Labs. The interaction of fluid systems and fabric is both the most basic of recovery system (parachute) problems, and perhaps the most difficult fluid structure interaction problem to solve. By beginning with simple problems, and continuously increasing the complexity, we have created early examples of where this simulation technology may lead. Along the way, we will include model size, solution time, and project to problems that will be solvable in the next two years. Additionally, we will report on required algorithmic enhancements and our suggestions on how to approach these. We will also present examples where we begin to apply the recently added Incompressible Navier-Stokes solver in LS-DYNA 960. Unfortunately, we will not report on comparisons to test data as, at the time of this writing, these are not available.

• DIC-based Full-Field Calibration using LS-OPT®: An Update

  Stander,N, Basudhar,A, Gandikota,I, Du Bois,S, Kirpicev,D, Livermore Software Technology Corporation, Livermore, CA;, Witowski,K, Ilg,C, Haufe,A, DYNAmore GmbH, Stuttgart, Germany;, Svedin,Å, DYNAmore Nordic, Linköping, Sweden

  This paper extends a 2017 study on full-field calibration using Digital Image Correlation (DIC) and the Finite Element Method to identify parameters of a material model developed for elastoplasticity. DIC is an optical method which provides full-field displacement or strain measurements for mechanical tests of materials and structures. It can be combined with the corresponding fields obtained from a Finite Element Analysis to identify constitutive properties. The methodology, which involves the solution of an inverse problem, consists mainly of two new core features namely (i) multi-point histories and (ii) suitable curve similarity measures. Multi-point histories are response curves which are evaluated at multiple spatial locations and extracted from simulations and experimental data. To improve on the previously used Euclidean curve distance measure, the Discrete Fréchet (DF), Dynamic Time Warping (DTW) and Partial Curve Mapping (PCM) measures were developed and validated for multi-point histories. An interface to a commercial DIC package, as well as two text-based generic interfaces, was also developed. A tensile test example was used to validate and demonstrate the methodology based on the DIC measurement of spatial point-wise strains. The example validated the code but revealed potential problem areas, such as solution stability, requiring further investigation.

• Die Attach Process using Adaptive ISPG in LS-DYNA

  Ayush Kumar, Vivek Pawar

  The die-attach process is a crucial step in electronic packaging, where semiconductor chips (dies) are securely bonded onto substrates (e.g., lead frames or printed circuit boards). The process typically in-volves applying an adhesive or solder material to join the die and substrate. It ensures electrical con-nectivity, dissipates heat, and protects the delicate semiconductor components. Precise die-attach (DA) techniques are vital to guaranteeing the reliability and performance of electronic devices, as improper bonding can lead to connection failures and reduced overall functionality of the packaged components.

• Digimat Material Model for Short Fiber Reinforced Plastics at Volvo Car Corporation

  M. Landervik (DYNAmore Nordic), J. Jergeus (Volvo Car)

  A pilot study has been done at Volvo Cars Corporation (VCC) to explore the potential of Digimat as material model for car components made of short fiber reinforced thermoplastics. It has been a joint project between Safety and Durability departments. It thus spans several types of analyses using both LS-DYNA, Abaqus and Nastran as finite element solvers. Additionaly, nCode DesignLife is used for evaluation of fatigue.

• Dimensionality Reduction of Crash and Impact Simulations using LS-DYNA

  C. Bach (BMW/Technical University of Munich), L. Song (BMW), T. Erhart (DYNAmore), Prof. F. Duddeck (Technical University of Munich/ Queen Mary University of London)

  Automotive crash simulations of full vehicle models still constitute a large computational effort which can be a major problem for applications requiring a large number of evaluations with varying parameter configurations. In some applications, highly similar simulations frequently need to be carried out multiple times with only minor local parameter modifications. At the same time, large amounts of numerical simulation data increasingly become available in industrial simulation databases as part of the progressive level of digitalization of automotive development processes. Data-driven modeling methods are an area of active research, aiming to exploit this new “treasure” in order to find interesting patterns and accelerate predictions.

• Direct Multi-objective Optimization through LS-OPT® using Small Number of Crashworthiness Simulations

  Tushar Goel, Nielen Stander - Livermore Software Technology Corporation, Yih-Yih Lin - HP

  Genetic algorithms typically require a large number of simulations, which would be economically prohibitive for crash simulations without the advent of today’s cost-effective multi-core computers. A study is conducted to seek improvements while restricting the number of simulations and exploiting the ability to use parallelization. The parallelization, achieved by simultaneously running multiple simulations for each GA generation on a HP quad- core cluster, resulted in a significant time savings. Furthermore, the optimal distribution of computational effort to achieve the greatest improvement in performance was explored. A crashworthiness simulation of a vehicle with 58,000 element finite element model was used as a test example. Various population sizes and numbers of generations were tried while keeping the total number of simulations constant. The optimization performance is also compared with Monte-Carlo and space filling sampling methods. It is observed that using GA, one can find many feasible and trade-off solutions. It is beneficial to allow a greater number of generations to get good trade-off solutions. Significant improvements in the performance were observed.

• Discrete Element Analysis of Idealized Granular Geometric Packing Subjected to Gravity

  M. Faraone, J. Chung, M. Davidson (University of Florida, Bridge Software Institute)

  This paper presents discrete element analysis models for studying quasi-static stress states in idealized granular materials subjected to gravity, and utilizes geometric packings and contact mechanics. The theoretical description of granular materials in assemblies of microscopic particles is a challenging task. The particle assemblies characterize in-situ initial and boundary conditions. In turn, the conditions are used in solving the equations of motion of the particulate system under stress equilibrium states (via a network of particle contact forces and various degrees of dissipative interparticle friction).

• Discrete Element Modelling of a Metamaterial for Launcher Tanks Dynamic Experiments

  T. Legaud, E. Grippon, V. Lapoujade, P. Chiambaretto (DynaS+); S. Nguyen, Y. Gourinat (Isae-Supaero); V. Fascio (Ateca)

• Discussion on NVH Analysis with Various Eigensolvers in LS-DYNA

  Zhe Cui, Yun Huang, Roger Grimes, Livermore Software Technology Corporation

  NVH (Noise, Vibration and Harshness) analysis is a new area of application of LS-DYNA in automotive industry, in addition to the existing applications of crashworthiness and occupant safety analysis. NVH analysis heavily relies on the eigenmode solutions of the structures. Due to the increasing size of the finite element models of automotives and parts, a fast and efficient eigensolver is strongly preferred. During the past two years, a new eigensolver technology, MCMS (Multi-level Component Mode Synthesis), was implemented to LS-DYNA. This method reduces the large scale finite element model to a smaller model, using a recursive application of the Craig-Bampton substructuring approach. Thus less computational resources are required in MCMS.

• DM.inspect: customizable quality control of LS-DYNA input files

  S. Mattern (DYNAmore), M. Koch (Porsche), R. Bitsche (SCALE)

  LS-DYNA models for industrial applications are often composed from several smaller sub-models. For example, in the automotive industry the different components of a car are usually modelled separately. These “include files” may be built-up in different departments of the same company or even developed by external suppliers. Due to the huge variety of features and functionalities in LS-DYNA, it is a good idea to set up general rules for the sub-models to achieve robust and efficient simulation models for production. Also, the successful assembly of models can be assured by defining generalized modeling guidelines, especially for the interaction of the different include files.

• DOE SENSITIVITY ANALYSIS WITH LS-OPT AND VISUAL EXPLORATION OF DESIGN SPACE USING D-SPEX

  Katharina Witowski, Heiner Muellerschoen, Marko Thiele - DYNAmore GmbH, Uwe Gerlinger - AUDI AG

  This paper describes the approach of a DOE (Design of Experiments) sensitivity analysis using LS-OPT in conjunction with AURA for simulating the radiation of a diesel particle filter. The process flow from preprocessing to the visual evaluation of the results using the D-SPEX (Design SPace EXplorer) software is presented. For the purpose of this sensitivity analysis the geometrical arrangement as well as polynomial curves from the AURA input had to be parameterized. Further more various discrete and coupled scalar parameters where used in this investigation.

• Drag Coefficient Optimization for a Sports Car Using the Coupling Between LS-DYNA® ICFD Solver, LS-OPT® and DEP MeshWorks Software

  M. Seulin, M. Le Garrec, A. Poncet (DynaS+), I. Çaldichoury (ANSYS LST), K. Gudlanarva (Detroit Engineered Product)

  Vehicle aerodynamics are one of the key points allowing to improve the vehicle dynamic behavior, to improve performance and to reduce fuel consumption. The vehicle aerodynamics have been studied in wind tunnels for several decades. Numerical simulations are increasingly used in addition of physical testing and permit to increase the number of design experimentations with cost and time savings. When CFD engineers are looking into optimizing the global aerodynamics of a car, numerous factors are taking into considerations. A car is a very complex assembly that must fit with multi-physical requirements updated along the vehicle project (design aesthetic, crash safety, weight, vibrations, noise, performances, design manufacturing, etc.) to find the best compromise according to initial specifications. DynaS+, ANSYS-LST and DEP are working closely with automakers across the world on various applications. Often, the automakers are sharing their work in conferences only several years after for obvious innovative competitive reasons. The aim of this work is to demonstrate what the current innovative technologies are, and methodologies used on aerodynamic applications using open source sports car data. Like in the majority of aerodynamic studies, in the present work, the objective was to reduce the aerodynamic drag coefficient of our model. A design optimization was performed on the initial design with the help of the advanced morphing capabilities of the DEP MeshWorks© solution coupled with the optimization software LS-OPT and the Incompressible Computational Fluid Dynamics (ICFD) solver LS-DYNA.

• Drag Force Simulation on Blast Loaded Fabric Roof

  M. Hadjioannou, E. Sammarco, M. Barsotti (Protection Engineering Consultants)

  An important consideration in predicting the dynamic motion of highly deformable structures subject to blast loads is the effect of drag force. A representative example of this condition is a blast-loaded non-breathable fabric roof, typically used for tents or other aesthetic fabric structures. A fully coupled fluid-structure interaction (FSI) analysis to simulate the interaction of the fabric roof with the air domain is theoretically possible, but is complex and requires significant computational effort. This study presents an alternative approach of including drag force in LS-DYNA® without the need to employ any form of computational fluid dynamics (CFD). Using the keyword *LOAD_MOTION_NODE, the velocity component of each node of the roof fabric elements is used as a variable to calculate the nodal drag force using the dynamic pressure equation. The calculated drag force is then applied at each time step as a nodal force that is opposite to the direction of motion and parallel to the element normals that represent the roof fabric. Results from a validation study using this approach are presented, and a case study involving the response of an arched roof fabric canopy subjected to blast loads is also discussed.

• Drape Simulation: Textile Material Model for Correct Property Reproduction to Improve the Preform Development Process of Fiber-Reinforced Structures.

  O. Döbrich, T. Gereke, Ch. Cherif (Institute of Textile Machinery and High Performance Material Technology, Technische Universität Dresden)

  The deformation behavior of textiles requires unconventional assumptions for successful drape simulation. The ®special performances in shearing, stretching and bending were implemented in LS-DYNA with user friendly subroutines. The general deformation behavior was considered by particular strain rates. A fully nonlinear and orthotropic material model was implemented to reproduce the character of the deformation mechanisms, shearing and stretching. The nearly negligible bending resistance was realized within a laminate formulation, which allows to set up an independent bending performance. Additional features such as pseudo-plastic shearing deformation or bending rigidity controlled by the bending side and direction was included. The simulation model was used to carry out complex drape simulations. A special afford was made in dealing with textile pre-treatments, which have local effects on the deformation behavior. Fixations affect the drapability and improve the handling of textile preforms. The material model and consequently the drape simulation are tools for a complex development process for textile preforms. The complete virtual development chain can lead from the textile good, with its special mechanical behavior, over the caused localization for special pre-treatment zones to a fully shaped and self-stable preform for complex shaped fiber-reinforced structures. An approach for composing this development chain will be introduced and presented.

• Drilling process modelling using SPH

  Virginija Gyliene, Vytautas Ostasevicius, Martynas Ubartas (Kaunas University of Technology, Lithuania)

  Numerical methods became a powerful tool to understand such complicated process as cutting processes. Based on finite element techniques, firstly a big challenge – geometric modeling of bodies coming in contact interaction and mesh size/zone choice and creation. Secondly, today’s we now that finite element modeling is sure tool in the research of cutting processes after many series of experiments. So, here is the purpose to get reliable solution more quickly. ® The latest versions of LS-DYNA present the possibilities of Smooth Particle Hydrodynamics (SPH) method. This method was used in 3D drilling process modeling. Solution was done assuming high impact contact interaction, when cutting tool was assumed as non-deformable rigid tool, made of solid elements and work-piece consisted of particles instead of elements. SPH model was created by SPH generation interface from solid nodes. The papers will presents some aspects of multi edge cutting process modeling (drilling) using SPH method, as contact definition and SPH control. Either work-piece failure by tool motion (feed and rotation) was generated. So, two movement laws were defined. Firstly, the understanding of SPH method also is desirable for its appreciation that this method is “natural” considering the chip separation process. Secondly, this method is so-called as “fast” method as concerns Kernel function. These mentioned aspects were reason for the choice of SPH method for drilling process modelling with the purpose in further analysis to apply ultrasonic excitation. Firstly, the paper presents drilling experimental setup. Also the paper describes the techniques of geometrical model generation using SPH particles. The techniques of modelling of high impact contact interaction are presented.

• Drilling rotation constraint for shell elements in implicit and explicit analyses

  Tobias Erhart (DYNAmore GmbH, Germany), Thomas Borrvall (DYNAmore Nordic AB, Sweden)

  A subordinate but interesting detail in theory and application of shell elements is investigated in this study, namely the drilling rotation constraint approach. Standard shell elements exhibit 3 translational and 3 rotational degrees-of-freedom at each node. While two nodal rotations are directly associated with bending and twisting modes, the third rotation about the shell normal (also known as the drilling rotation) does not provide any resisting force or stiffness by itself. This fact leads to zero valued components in the stiffness matrix for implicit analyses, which in turn results in a system of equations that cannot be solved. Therefore a small amount of stiffness in form of a torsional spring is artificially added just to remedy the singularity but not to affect the solution too much. This is absolutely necessary to deal with implicit analysis, otherwise no results could be obtained. On the other hand, it might be helpful to have this option also available in explicit analyses to improve results in special situations. It is the intention of this paper to present the theoretical background of this phenomenon and to illustrate the influence of the constraint method in several numerical examples.

• Driving Through Flooded Road

  Bijoy Paul, Rachel Hysong, Babak Tehrani, Elizabeth Welch, John Davis, Amit Wavde (General Motors)

  Driving through flooded roads is always a challenge. Hydrostatic as well as hydrodynamic pressure can cause serious damage to the vehicle. Damage can adversely affect the performance of the vehicle in many ways. For example, high stress and strain can cause part failure, water ingestion into electrical components can lead to instant shutdown of the electrical system, corrosion, due to interaction with water can affect the performance and cosmetics of the vehicle. All of these can be costly fixes that are extremely dissatisfactory to our customers. General Motors has been designing and building state-of-the-art vehicles for more than a century. Safety, structural durability, part integrity, and performance are key features of every vehicle that General Motors produces. General Motors constantly invests in new technology and methods to improve quality, performance, and customer satisfaction. Smooth Particle Hydrodynamics (SPH) was developed in the late 70s. This mathematical advancement was transformed in the form of application in the recent past. The application has now been widely accepted by the CAE analysis community to study Fluid-structure-interface, water path analysis, and other hydrodynamic behavior, related to water and oil. General Motors has worked with LS DYNA® to improve performance issues of its vehicles in many areas of interests such as occupant safety, crash worthiness, structural durability and most recently, on water intrusion issues using SPH. This study involved structural durability analysis of a vehicle when driven on a flooded road. SPH particles were created to mimic the flooded road. A non-linear transient (crash) model was selected for the analysis. A node-to-surface contact was established between the SPH particles and vehicle. The vehicle was given an initial velocity of 30 km/hour, and the wheels were let to spin with the calculated rotational velocity. The LS-DYNA simulation was run for 400 milliseconds and plastic strain outputs were measured. A physical test was scheduled. Strain gauges and strain rosettes were affixed at the areas where computer simulation results were measured and recorded. The physical test was then performed at the General Motors Milford Proving grounds. Analysis results were then compared with the physical test results. In conclusion, a good correlation was observed between CAE (SPH analysis) and test results. SPH analysis is computationally very intense. Therefore, steps are being discussed to shorten the total computational time.

• DROP ANALYSIS OF THE SKID LANDING GEAR OF THE LIGHT HELICOPTER

  Alexander V. Konyukhov, Sergey A. Mikhaylov - Kazan State University, Russia

  The analysis of helicopter during landing includes both complicated experimental tests and numerical calculation. Up to now very simple models in helicopter engineering have been used in Russia. Contemporary investigation of these problems involves using modern engineering software. The mechanical models included in these software allow to describe highly nonlinear dynamic behavior of engineering structure. This article contains rudimentary step-by-step development of numerical model to analyze behavior of skid landing gear in order to obtain optimal numerical model. Main points of the optimal numerical model are related to reducing cost of the verification experiment as well as hardware requirements. The base software for numerical activities is LS-DYNA with pre- and post- processors in ANSYS.

• Drop Analysis of Waste Transfer Flask

  Suresh Babu, Jayanta Biswas - Atomic Energy of Canada Limited

  The present paper describes the drop analyses performed on a waste transfer flask using LS-DYNA® finite element software. Radioactive waste generated during retubing of CANDU®6 reactors are placed in waste containers. Waste transfer flasks are used to transfer waste containers from the reactor building to storage structures. The waste transfer flask is a complex mechanical assembly made of double wall steel shells filled with lead. At the storage area, the waste transfer flask is lifted by a crane to transfer the waste container to the storage structure. During lifting of the waste transfer flask, it is necessary to know the consequence of an unlikely drop event. Analyses have been performed to assess the structural response of the waste transfer flask subjected to impact loads due to various drop events resulting from lifting of the waste transfer flask at the storage area. The waste transfer flask is dropped by considering various orientations viz., dropping on edges, corners and base. Based on the drop analysis the mode of failure and plastic deformation of various components of the waste transfer flask and the waste container is predicted. Also, an assessment is made regarding the structural integrity of the waste container and its retrievability after various drop events.

• Drop Simulation for Portable Electronic Products

  Raymon Ju, Brian Hsiao - Flotrend Co., Taiwan

  The portable electronic devices are becoming smaller and lighter in recent years, and hence these products are easily damaged under the drop and impact conditions. Traditionally, manufacturers must have lots of mockups and samples to simulate the impact behavior through experiment. To minimize the development period and the try-and- error costs, ODMs in Taiwan begin to predict the impact behavior by LS-DYNA. For ODMs who want to establish CAE capability, there are two main challenges: (1) First challenge is to determine the opportune moment to introduce the CAE tools, which also implies the traditional design flow should be rearranged. (2) The maximum dimension of portable electronic devices is usually less than 30 cm, so mechanism features are relative small and difficult to build up a complete FEM model. The main theme of this present is to provide a prediction about drop behavior of the portable electronic products in the early design stage and verified with the experiment.

• Drop Test Analysis of a Lamy Pencil

  Dr.-Ing Matthias Hörmann, Steffen Schiele - CADFEM GmbH, Reinhard Probol - LAMY GmbH

  Consumer products like cell phones, personal digital assistants, dish washers or cookers, to name just a view of them, are often exposed to drop during transportation to the customer and during usage in life time. Pre-damage, failure or malfunction due to drop is typically not acceptable and will lead to refusal through the costumer in addition with a correspondingly amount of financial and prestige loss. The present work deals with the numerical simulation of a drop test of a LAMY pencil. Special emphasis is put on the drop onto the apex of the pencil, which is most harmful to the lead mechanics. In experiments, failure of the lead mechanics was observed for this drop position, which was a result of localized high stresses in combination with plastification in those regions. It was the goal of the simulations to investigate whether an exchange of the used material for the lead mechanics would meet the requirements. Special emphasis was hereby placed on the reproduction of the overall lead kinematics translational and rotational wise as well as to account for the behavior of the floor material.

• Drop Test Analysis of a Lamy Pencil

  Dr.-Ing Matthias Hörmann, Steffen Schiele - CADFEM GmbH, Reinhard Probol - LAMY GmbH

  Consumer products like cell phones, personal digital assistants, dish washers or cookers, to name just a view of them, are often exposed to drop during transportation to the customer and during usage in life time. Pre-damage, failure or malfunction due to drop is typically not acceptable and will lead to refusal through the costumer in addition with a correspondingly amount of financial and prestige loss. The present work deals with the numerical simulation of a drop test of a LAMY pencil. Special emphasis is put on the drop onto the apex of the pencil, which is most harmful to the lead mechanics. In experiments, failure of the lead mechanics was observed for this drop position, which was a result of localized high stresses in combination with plastification in those regions. It was the goal of the simulations to investigate whether an exchange of the used material for the lead mechanics would meet the requirements. Special emphasis was hereby placed on the reproduction of the overall lead kinematics translational and rotational wise as well as to account for the behavior of the floor material.

• Drop Test into Water and Wave Impact Simulations of a Novel 7-Meter Plastic Boat with LS-DYNA

  Martin Vézina, Arash Firoozrai - SimuTech Group Inc.

  The US Congress, in its desire for a safer boat for the US Navy, contracted Stanley Widmer Associates Inc. to design and build a novel rotationally molded 7-meter boat using a patented "kiss-off" design. A first ever made prototype will be ready for trial in 2010. The material used for most of the boat, high density cross linked polyethylene, and the double hull with “kiss-off” design should, among other advantages, increase the boat's impact resistance compared to fiberglass and aluminum boats. This paper presents numerical fluid structure interaction simulations done on the 7-meter boat, utilizing LS-DYNA, in order to investigate its structural integrity under water impact. Drop test into water simulations were done in the first phase of this numerical investigation. The boat was dropped at different heights and angles. A modal analysis was also done in Phase 1. A procedure to generate realistic waves was developed in the second phase. Explicit simulations with the boat going through waves at different velocities were done. A similar fiberglass boat was finally compared to the plastic design. Results from the drop test simulations and the modal analysis in Phase 1 clearly showed a critical flexural area. A modified design was run in Phase 2. LS-DYNA analysis results from Phase 2 predict that the plastic boat can go through 3-foot waves at 40 knots without damage while the fiberglass one has predicted damage at 30 knots. Overall, the numerical simulations show that high density cross linked polyethylene could be the new age of boating material.

• Drop Test Simulation and Verification of a Dishwasher Mechanical Structure

  O. Mulkoglu, M. A. Guler (TOBB University of Economics and Technology), H. Demirbag (Arcelik)

  It is critical for dishwasher manufacturers to design the front door hinge system and the structural components of a dishwasher assembly in terms of appearance and satisfying functional requirements. Since dishwasher users and customers request receptive quality elements from front door, it is necessary for example to know how many kilograms of decorative wooden door can be assembled to the built-in front door without endangering the durability on every single opening state.

• Drop Test Simulation of a Cooker Including Foam Packaging and Pre-stressed Plastic Foil Wrapping

  Dan Neumayer - Bosch-Siemens-Hausgeräte, Madhukar Chatiri, Matthias Höermann - CADFEM GmbH

  The present work deals with the numerical simulation of a drop test of a cooker including packaging foam and plastic foil wrapping. Additionally the pre-stressing of cooker and packaging due to thermal shrinkage of the plastic foil has been taken into account in the numerical investigation. For this, a thermal pre-stressing simulation of the plastic wrapping has been included before the actual drop test of the whole assembly has been conducted. The permanent deformations of the cooker nearby the impacted edge as well as the deformation of package foam in the vicinity of the impacted edge were the primary areas of interest and compared with experimental data. LS-DYNA [1] was used to perform the drop test simulation of the cooker as well as the thermal pre-stress simulation of the plastic wrapping.

• Droptower Impact Testing & Modeling of 3D-Printed Biomimetic Hierarchical Composites

  Grace Xiang Gu, Steven Kooi, Markus J. Buehler (Massachusetts Institute of Technology), Alex J. Hsieh (Massachusetts Institute of Technology,US Army Research Laboratory), Chian-Feng Yen (US Army Research Laboratory)

  Inspired by the hierarchical designs of natural materials, this paper highlights the use of 3D-printing as a plausible pathway to discern and differentiate material attributes critical to desirable impact properties. A comprehensive study was focused on the influence of three different hierarchical designs derived from a nacre-like architecture, where two base materials varying vastly in properties were used to evaluate the low-velocity impact on 3D-printed hierarchical materials. The work presented here develops a numerical model to characterize the failure modes and damage behavior of various hierarchical materials organized in different configurations. The finite element software LS-DYNA ® is used where force-displacement responses and damage patterns obtained from simulation are compared with experimental results obtained from drop tower impact tests. This study clearly demonstrates that the emerging 3D-printing technology can enable rapid prototype towards hierarchical ductile/brittle hybrid designs for future impact resistant materials.

• Ductile Failure in Large-Scale Analyses of Aluminium Structures

  D. Morin, T. Berstad, O.S. Hopperstad, M. Langseth (NNTU)

  Modelling of ductile failure in aluminium alloys is of high importance during the design of lightweight structures subjected to impact loading. Such designs are today based on numerical analyses and their credibility is crucial to reduce the development time and costs of such products. Under impact conditions, lightweight structures are most likely exposed to severe loadings and failure is a phenomenon which cannot be ignored. To accurately capture ductile failure, an analyst should employ advanced constitutive models to describe properly the local behaviour of the materials as well as proper discretization to predict the correct deformation mode of the structure. This approach would lead to the use of advanced anisotropic yield surfaces to capture accurately the anisotropic yielding and plastic flow of aluminium alloys as well as fine solid element meshes to predict correctly the strain localization process [1]. Unfortunately, these approaches require large investments from the user both in terms of calibration of the constitutive models and CPU time when running the numerical analyses. These large costs prevent the use of these techniques into large-scale analyses and simplified approaches are still required within an engineering environment. The aim of this work is then to propose a constitutive and failure criterion suitable within an engineering context both in terms of calibration cost and applicability for shell element analyses. The yielding and plastic flow of the investigated aluminium alloy is then reduced to an isotropic non-quadratic model using *MAT_36 and ductile failure is predicted using the Cockcroft-Latham failure criterion added to the model through the *MAT_ADD_EROSION keyword. A simple calibration procedure based on a single tension test is applied to calibrate the constitutive model and the failure criterion. Based on the tensile test results, a simple but cost-effective regularization scheme is proposed to handle the mesh sensitivity of the failure model for shell elements of various sizes. The calibration and validation of the proposed approach is presented based on quasi-static and low-speed impact tests carried out on large aluminium stiffened panels recently published by Morin et al. [2]. A satisfactory agreement is found between the proposed modelling approach and the experiments.

• Ductile Fracture Prediction with Forming Effects Mapping of Press Hardened Steels

  L. Knoerr, T. Faath, S. Sikora (ThyssenKrupp Steel NA), P. Woelke, B. Benowitz, B. Hiriyur (Weidlinger Associates)

  The escalating usage of Advanced High Strength and Press Hardened Steels to enhance crashworthiness while improving fuel efficiency through light-weighting of vehicles, has become a surmountable challenge to the auto industry. Furthermore, the expanded safety assessment like the IIHS-Small Overlap crash test greatly intensify the need for an accurate and reliable fracture prediction model, that will take into account the forming effects of the structural components critical to the inherent load cases. In this study, a press hardened steel component with ultimate tensile strength of 1500 MPa with initial 1.5mm gage thickness, is investigated under experimental and virtual three point bending load conditions.

• Dummy Model Validation and its Assessment

  S. Stahlschmidt, A. Gromer, Y. Huang, U. Franz (DYNAmore GmbH)

  This paper describes the dummy model validation process applied in several FAT and PDB pro- jects. The modeling activities started 19 years ago and the validation process was enhanced continuously during this period.

• Dummy-Positioning for a Whiplash Load Case using LS-DYNA Implicit

  A. Hirth (Daimler), A. Gromer (DYNAmore), T. Borrvall (DYNAmore Nordic)

• Durability assessment of welded structures based on welding simulation with LS-DYNA ®

  Andriy Krasovskyy (DYNAmore Swiss GmbH), Antti Virta (Winterthur Gas & Diesel Ltd), Thomas Klöppel (DYNAmore GmbH)

  The importance of welding for modern structural engineering cannot be emphasized enough. Different techniques are currently applied in the industrial environment offering almost unlimited possibilities regarding manufacturability with high cost effectiveness. At the same time the requirements on welded structures are increasing and so the requirements on the design methods. This paper presents an advanced calculation method for fatigue assessment of welds based on the simulation of a welding process in LS-DYNA ® , thermophysical material modeling and fracture mechanics. The proposed method considers the most important aspects for durability prediction of welds. Applying worst-case assumptions, fatigue limits derived by the weight function method can be used in the lifetime assessment of complex welded structures together with the critical plane approach in order to consider a multiaxial nonproportional loading.

• Durability Study for Tractor Seat Using LS-DYNA ®

  Jithesh Erancheri, Ramesh Venkatesan (Kaizenat Technologies Pvt Ltd)

  Today in many tractors with enclosed cabs, an extra seat named as 'instructor seat' are available. As a regular driver seat, this seat should also undergo the same testing and product validation process. This seat is incorporated to serve various purposes like enhances the training of tractor operators, facilitates communications between workers, improves the demonstration of for-sale tractors, transports workers to worksites, assists operations requiring extra help etc. LSTC's LSDYNA introduced a powerful vibro-acoustic solver which can address almost all major problems in the frequency domain. In this paper, we used the explicit capability of LS-DYNA to model the drop of tractor Instructor seat (henceforth called a I -Seat) and then the frequency domain capability to estimate the damage of parts that undergoing steady state loading . We have used LS-DYNA's new fatigue solver capability for SSD loading to predict the damage.

• DYNAFORM 5.8.1 – New Features and Future Development

  J. He (DYNAFORM Product Manager, Engineering Technology Associates Inc.)

  This presentation will provide details regarding the recent release of DYNAFORM Version 5.8.1. DYNAFORM is an FEA software solution which guides the engineer through a wide range of stages in the manufacturing, from cost estimation and die face design to formability analysis, springback prediction and springback compensation. This version promises to deliver a robust environment for engineers to simulate and analyze the entire die system. Significant enhancements were included in this version, many of which are delivered through the Die Face Engineering (DFE) module. DFE now offers the capacity to parametrically build die faces for a symmetrical part. A new ‘product change replacement’ feature allows the user to retain the current die face design and simply drop in new product design surfaces, saving the user a great deal of time while providing greater flexibility. DYNAFORM 5.8.1 allows the user to set up a personalized ‘drawbead library’ which links the line bead force and the drawbead geometry shape. As a result, the user can elect to run the simulation with either the line beads or geometry beads. DYNAFORM future development will be focused on optimization which will significantly reduce the manual adjusting work for simulation engineers. This will ultimately make simulation analysis more automated.

• Dynamic behaviour study of a satellite propellant tank using numerical and experimental vibratory tests

  T. Pierrot, A. Guilpin, T. Legaud, V. Lapoujade (DynaS+), J.-E. Chambe, M. Charlotte, Y. Gourinat (Université de Toulouse), M. Delorme (ATECA)

  The ecological transition necessity makes the use of cryogenic fluids more and more relevant. However, experimental tests and associated modelling of those liquids dynamic vibratory behaviour remain extremely challenging. Indeed, security, control and conditioning are critical issues due to the intrinsic fluid instabilities. Among those critical fluids, liquid hydrogen and supercritical xenon are both highly used in the spatial propulsion domain. Because of their hazardous behaviour, only few experimental dynamic tests have been performed to improve the knowledge of their behaviour inside a vibrating tank.

• Dynamic Constitutive Model for Polymers with Considering Strength-Differential Effect and Strain Rate Dependency

  T. Tsuda, ITOCHU Techno-Solutions Corporation, Umeda, Kita-ku, Osaka, Japan;, A. Abe, R. Akita, ITOCHU Techno-Solutions Corporation, Kasumigaseki, Chiyoda-ku, Tokyo, Japan;, T. Numata, Sumitomo Bakelite Co., Ltd., Murotani, Nishi-ku, Kobe, Japan;, K. Mimura, Osaka Prefecture University, Gakuen-cho, Naka-ku, Sakai, Japan;, S. Tanimura, Emeritus Professor of Osaka Prefecture University and of Aichi University of Technology

  It is known that the dynamic behavior of polymers depends greatly on not only the strain rate but also the hydrostatic pressure, and furthermore, the volumetric change after plastic deformation is larger than that of the metal material. Therefore, it is necessary to clarify these material properties for high precision simulation of polymers. In this study, we newly extended the Tanimura-Mimura 2009 model to simulate the dynamic behavior of polymers which depends not only on the strain rates but also on the hydrostatic pressure, and implemented using the user subroutine function of the impact analysis code LS-DYNA®. Then, dynamic tension and compression tests were performed on polycarbonate specimens using the Sensing Block Type High Speed Material Testing System, and material parameters of the extended constitutive equation were determined. Furthermore, verification simulation by LS-DYNA using these constituent equation and material parameters was carried out. As a result, the simulation of the dynamic behavior of tension and compression agreed well with the dynamic test results, and the validity of the constitutive equation and its material parameters were confirmed.

• Dynamic Design Analysis Method to Evaluate Shipboard Shock in LS-DYNA®

  Michael Koehler, William McCoy, Milan Patel, U.S. Navy – Naval Surface Warfare Center, Dahlgren Division

  The Dynamic Design Analysis Method (DDAM) provides a method for analyzing shipboard components that are subjected to a shock event due to an underwater explosion. Typically, these events are caused by a near miss explosion that results in a severe shock event due to the transient motion of the ship or submarine from the forces imparted on the hull of the vessel.

• Dynamic Explicit SPH Simulation and Material Characterization of Road Tankers using LS-DYNA

  C. Robb, G. Abdelal, P. Mckeefry, C. Quinn

  Crossland Tankers is a significant manufacturer of bulk-load road tankers from Northern Ireland. Thirty thousand litres of liquid are carried over long distances and varying road conditions. The effect of sloshing within the tank can significantly impact the driveability and lifespan of the tanker. As part of this project with Crossland Tankers, we will develop a model using LS-DYNA to investigate the applications as part of the design process.

• Dynamic FE Analysis of the High-Speed Planetary-Motion Mixer UM-500

  Alexey I. Borovkov, Vladimir A. Palmov, Dmitriy S. Mikhaluk, Denis V. Shevchenko - St.Petersburg State Polytechnical University,

  In the current paper the results of finite element non-linear mechanical analysis of the energy-saving high-speed planetary-motion mixer UM-500 are presented. The mixer is a system consisting of two milling chambers partly filled with substance to be milled. Milling chambers are in compound motion: rotation about vertical central axis and self-rotation about moving sloping axes. To perform dynamic analysis detailed finite element model is created based on CAD model. Finite element model considers nearly all features of the real construction. By means of LS- DYNA the detailed finite element analysis of dynamic non-linear process of mixer takeoff out of the casing in the result of emergency situation is performed with use of elasto-plastic material model with strain-based failure crite- rion. Dynamic analysis of the rigid-body motion stability of the mixer at speed-up regime is carried out for simpli- fied mathematical models

• Dynamic Load Balancing

  B. Wainscott (LSTC)

  MPPDYNA begins each simulation by splitting the model into multiple pieces (domains), and assigning each domain to a CPU core. This is referred to as “domain decomposition.” Efficient MPP processing requires that, as much as possible, every CPU core is kept busy doing useful work. That is to say, each domain should represent the same amount of work to be done. If one core is assigned a domain that is too large, then at certain points in each timestep cycle the other cores will be idle, waiting for this core to finish its calculations. The initial decomposition is based primarily on measured execution times for the different types of elements and the different material models. And it has been the case that once the domains are determined, they persist through the duration of the calculation. This approach has two significant problems. First, the element costs used during decomposition are not perfectly accurate. As material types are added, routines are modified, compiler options changed, and new CPUs are available, keeping this decomposition timing information up to date is simply infeasible. But even if that could be done, the second issue is that for most materials the computational cost of the material changes during the calculation. As elements distort, or exceed their elastic limit and begin to experience plastic deformation, the element evaluations can become more time consuming. This leads to the inevitable conclusion that any static decomposition will result in at least some computational imbalance. As core counts increase, the need for dynamically adjusting the decomposition will also increase.

• Dynamic Pulsebuckling Analysis of FRP Composite Laminated Beams Using LS-DYNA

  Zheng Zhang, Farid Taheri - Dalhousie University

  Buckling and post-buckling of composite structures have been important research topics since composite materials became widely used in engineering. As a result, significant volume of research has been done on their static stability, while relatively less has been devoted on characterizing their dynamic buckling and post-buckling response. The literature became particularly scares when considering the dynamic pulsebuckling and post buckling of axial components subjected to axial impact. This paper, therefore, presents the findings of our finite element analysis of dynamic pulsebuckling response of slender laminated fiber reinforced plastic (FRP) composite beams, with initial geometric imperfection, subject to axial impulse using LS-DYNA. Dynamic pulsebuckling, as an instability form, or in the form of excessive growth of lateral or out of plane displacements, is resulted from a transient loading function of a single pulse with a magnitude greater than the static Euler buckling load. The FRP laminated composite beam with initial geometric imperfection, subject to axial impact of a moving object, is modeled by the Belytschko-Tsay shell element. The moving object is defined as a rigid wall with a mass and initial velocity. Dynamic pulsebuckling of an imperfect beam is characterized by the sudden and drastic increase in the lateral deflection while the axial load bearing capacity remains unchanged relatively when the impact momentum reaches a critical value. Numerical results show that momentum of the moving object may be considered as a viable parameter for predicting the dynamic pulsebuckling limit of the beam. In this investigation, the effect of initial geometric imperfection used to promote instability was investigated and was shown to be a significant factor in promoting pulsebuckling. The effect of boundary conditions was also investigated and the significances of the axial and rotational restraints were demonstrated with numerical examples. A predictive criterion for the onset of pulse buckling was also presented.

• Dynamic Simulation of Mechatronic Systems

  R.Cresnik, A.Rieser, H. Schluder - Virtual Vehicle

  A growing number of safety systems are implemented in modern vehicles. Thereby vehicles become more complex and in succession the quantity of potential error causes is increasing. Numerical simulation and prototype tests are used to investigate vehicle behaviour and prevent aberrations at an early stage. However, prototype tests on full vehicle level are not feasible in early development stages. Numerical simulation is an effective tool reducing development time and costs, but hardware tests are still necessary to verify the simulation results. To handle these challenges in the development process new developing methods are necessary. In this paper an interface, which provides the implementation of control systems into finite element solvers is presented. This interface allows a more realistic behavior of these systems in numerical simulation. Thereby it is a useful tool, to design and adjust mechatronic systems, like integrated safety systems, at an early stage of the development process. This coupling method can also be used to check actuator configurations in substituted mechanical systems. Needed forces and accelerations are known before experimental testing, but disturbance variables cannot be pre-calculated. Therefore this method offers a possibility to verify, if the range of capacity of the actuator, the frequency and efficiency of the control algorithm are able to handle the prescribed behaviour. In order to consider the behavior of all systems in a close to realistic manner, associated control units must be built into the finite element model. This will be a prerequisite for the realization of an optimized mechatronic system configuration in future vehicles.

• Dynamic Simulation of Mechatronic Systems

  R.Cresnik, A.Rieser, H. Schluder - Virtual Vehicle

  A growing number of safety systems are implemented in modern vehicles. Thereby vehicles become more complex and in succession the quantity of potential error causes is increasing. Numerical simulation and prototype tests are used to investigate vehicle behaviour and prevent aberrations at an early stage. However, prototype tests on full vehicle level are not feasible in early development stages. Numerical simulation is an effective tool reducing development time and costs, but hardware tests are still necessary to verify the simulation results. To handle these challenges in the development process new developing methods are necessary. In this paper an interface, which provides the implementation of control systems into finite element solvers is presented. This interface allows a more realistic behavior of these systems in numerical simulation. Thereby it is a useful tool, to design and adjust mechatronic systems, like integrated safety systems, at an early stage of the development process. This coupling method can also be used to check actuator configurations in substituted mechanical systems. Needed forces and accelerations are known before experimental testing, but disturbance variables cannot be pre-calculated. Therefore this method offers a possibility to verify, if the range of capacity of the actuator, the frequency and efficiency of the control algorithm are able to handle the prescribed behaviour. In order to consider the behavior of all systems in a close to realistic manner, associated control units must be built into the finite element model. This will be a prerequisite for the realization of an optimized mechatronic system configuration in future vehicles.

• Dynamics in Aerospace

  Dr. Yves GOURINAT - ENSICA Professor Mechanics & Space Techniques

  Airships Aircrafts Spacecrafts

• DynaWeld-Equivalent-Energy-Method

  T. Loose (DynaWeld)

• Early Design Validation of Vehicle Interiors for FMVSS 201 using IHIT and LS-DYNA

  Arun Chickmenahalli - International Automotive Components, Suthy C. Sivalingam - ESI North America, Thomas Weninger - ESI-Group

• Early Design Validation of Vehicle Interiors for FMVSS 201 using IHIT and LS-DYNA

  Arun Chickmenahalli - International Automotive Components, Suthy C. Sivalingam - ESI North America, Thomas Weninger - ESI-Group

• Economically Improving Crash Worthiness of a Large Propane Tanker

  Phillip H. Burnside - PPG Industries, Ed Hampton - Engineering Applied Sciences Inc.

  Approximately every three years a 65,000 lb propane tractor-trailer crashes resulting in explosion that usually kills several people. The study presented in this paper first simulates the effects observed at one of these accident sites. This was simulated in LS-DYNA by building a full length model of the tanker trailer and also including the liquid in the tanker. The presence of the liquid in the model provide the initial effects of liquid on the tanker. The resulting model correlated very closely with the actual observation seen at the crash site. Then a variety of options where explored to determine how to improve the crash worthiness of the tanker for several crash scenario's. The result of this work illustrated that for less than $20,000 the velocity that would cause failure could be raised from 20 mph to over 55 mph through the use of energy absorbing materials.

• Edge-to-Edge Cohesive Shell Elements in LS-DYNA

  J. Karlsson (DYNAmore Nordic), M. Fagerström (Chalmers University)

  This paper presents a new cohesive element in LS-DYNA for edge-to-edge connection of quadrilateral thin shells. Cohesive elements are an important tool for simulating the propagation of cracks in materials.

• Educational and Research Issues Concerning Virtual and Real Forming of Sheet Metal

  Raghu Echempati, Sarang Likhite - Kettering University

  The aim of this paper is to discuss the educational issues concerning real and virtual simulation of sheet metals such as steel, magnesium and aluminum. Although expensive, aluminum and magnesium are being viewed as promising candidates in some of the automotive stamping applications. The philosophy explained in this paper deals with providing concurrent experience of real and virtual forming of sheet metals to engineers. There are several manufacturing processes like Casting, Molding, Metal Removal, Metal Forming, etc. Several different kinds of materials like metals and non-metals like plastics, ceramics and composites are considered to manufacture engineering products. Choice of a particular material depends on the type of application. One of the major challenges and goals in manufacturing is to see how to transfer several different ideas generated out of both experimental and theoretical research in to a state-of-the-art technology that can be applied to manufacture better quality products. Research, both in terms of better modeling of a manufacturing process and experimentation concerns with conducting parametric product and process design studies in order to produce near net shape (final shape) of a product. Computers no doubt are very helpful in advancing this research. Computer simulation of a manufacturing process can help in better visualization and understanding the different stages as a product is being shaped. Computer simulation deals with mimicking on a computer what it takes to do a prototyping of a product in the real world. While we learn to “think with hands” as we make prototypes and products, we learn to “think with the knowledge attained” as you perform simulation studies. It is very important to properly validate the results of a computer simulation with real experiments so that scientific tools can be eventually generated eliminating or reducing the need for making costlier and time consuming prototypes. Metal forming is divided in to bulk forming and sheet metal forming. Processes like rolling, forging, extrusion and drawing fall under bulk deformation, while bending, blanking, drawing, hole-expansion and stretching fall under sheet metal forming area. Kettering University in Flint, MI offers a sheet metal forming class (MfgE-404) based on understanding the principles behind formability of real sheet metals and a new virtual forming class (ME-510) based on simulating the real sheet metal process on a computer. Both classes need a basic understanding of manufacturing process and engineering materials. In addition, a good understanding of virtual forming requires a basic knowledge of solid modeling and finite element techniques. These two courses are unique to Kettering University. Kettering University is also very supportive of promoting undergraduate and graduate education and applied research in the real and virtual metal forming area. Many stamping industries promoted this idea of a combined real and virtual forming experience gained by engineering graduates. The mechanical and the manufacturing engineering departments are working together to achieve these goals. A NSF/CCLI proposal has been submitted last year (not funded). A revised proposal again is being prepared for submission to NSF. Recently, Kettering University funded a research initiation and improvement (RI/I) grant that deals with comparing the formability of sheets made of aluminum and magnesium with steel. Vegter, Pijlman and Huetink [1] in their paper discussed the deviations that occur due to experimental errors. Uniaxial tensile tests (ASTM E 646) were conducted on aluminum samples to predict inconsistencies in the strain state. Kuwabara and Bael [2] presented the experimental and analytical results of biaxial tensile tests to predict the yield locus of aluminum alloy 6XXX-T4. Kim, et al [3] discussed the analysis of wrinkling initiation and growth of aluminum A6114-T4 deep drawing process with controlled blank holding force. Bifurcation algorithm is introduced in the elastic-plastic finite element method. Several benchmark studies have been undertaken to predict punch force, thinning and several other characteristics of a deep drawn aluminum A6016-T4 cup [4]. The results show a lot of inconsistencies between the different studies thus necessitating the proper understanding of the material behavior and the measurement techniques used for such studies.

• Effect of Explosive Charge Geometry on Boundary Surface Peak Pressure with Regard to Standoff Distance

  oseph Hamilton, Daniel Coleman, Karagozian & Case, Inc., 700 N. Brand Blvd., Suite 700, Glendale, CA 91203

  In an effort to better understand the effect of explosive charge geometry on blast effects, in particular with regard to standoff distance, this paper presents a study of three different geometries at varying standoffs. The geometries reviewed in this study were: cylinder, sphere, and rectangular cuboid. The explosive mass was held constant between all geometries, and the system was modeled with the LS-DYNA® structured Arbitrary Lagrangian-Euler (ALE) solver. The peak pressure on a reflective boundary surface was measured and recorded in order to quantitatively categorize the blast effects of each case.

• Effect of Hourglass Control on LS-DYNA® Concrete Constitutive Models in Low Velocity Impact Simulations

  Amirmohammad Samadzad, Matthew Whelan

  The performance of reinforced concrete structural components under impact loading has received significant attention over the past decade, with high fidelity numerical simulations supplementing the available experimental test data. Several studies have evaluated the prediction of impact force and displacement time histories, as well as cracking and spalling, using a number of constitutive models in LS-DYNA. Under-integrated hexahedral elements are typically used in these analyses with hourglass control introduced to suppress hourglass modes. Prior studies have demonstrated that finite element analysis of reinforced concrete beams to impact loading is sensitive to the hourglass coefficient, however several studies have limited their basis of selection of appropriate hourglass coefficients to relative hourglass energy and comparison of model predictions with experimental measurements of displacement and force time histories. Furthermore, studies contrasting the performance of different constitutive models have routinely used a single hourglass coefficient for all models [1, 2]. This may be problematic if individual constitutive models demonstrate unique sensitivity to the hourglass control.

• Effect of Material Characteristics on Wrinkling During Dome Forming of a Beverage Can using LS-DYNA

  R.E. Dick, J.W. Yoon -Alcoa Technical Center, USA

  Wrinkling of thin sheet metal products such as beverage cans continues to be experienced by can manufacturers and is observed with some aluminum material suppliers more than others. These wrinkles are caused by compressive instabilities during forming, and with small base diameter cans and light gauge material, the likelihood of this wrinkle formation increases. Manufacturing experience suggests that dome wrinkling is influenced by many factors such as mechanical properties of the aluminum sheet, tooling geometry, contact conditions including the effects of lubrication, and other process boundary conditions. It is also difficult to conduct an experimental analysis of compressive instabilities of these thin sheet metal products because the effects of all of the factors contributing to the instabilities are complex and small changes in these factors may produce widely varying results. Therefore, a numerical approach is recommended to separate the effect of each variable on wrinkle formation. This paper shows how strain-hardening and r-values influence wrinkle formation in its magnitude and frequency through dome forming of a beverage can based on a recent anisotropic yield function implemented as an LS-DYNA UMAT subroutine.

• Effect of side incubator padding on unrestrained child crash dummy under deceleration force

  Ali Rabiee (Cranfield University)

  Nearly 20 million low birth weight and premature infants are born each year in developing countries, 4 million die within their first month due to unavailability of incubators and neonatal intensive care. Neonates and infants that require an inter-hospital transfer or ambulance/vehicle transfer in an incubator could potentially face fatal and catastrophic events, once subjected to negative acceleration. The main factor affecting the applied force due to the harsh braking or collisional accidents to the neonate/infant is the configuration of the restraining system. By eliminating the restraining system or having low residual strength seat belts the neonate or infant can experience lifelong injuries or even death. The interior of an incubator in case the restraining system fails must be designed to protect the occupant. In this paper, the effect of the paddings on the incubator wall against the unpadded wall is studied on a crash dummy using LS-DYNA software. The deceleration pulse, velocity, and displacement are validated by a sled test at Cranfield Impact Centre (CIC).

• Effect of Soil Material Models on SPH Simulations for Soil-Structure Interaction

  R. F. Kulak (RFK Engineering Mechanics Consultants), L. Schwer (Schwer Engineering & Consulting Services)

  Currently, civil engineering design practice uses liner elastic soil properties for many soil- structure interaction problems. However, this approach falls short for problems in which the structure and soil undergo large deformations. With the availability of the high-performance computing (HPC) cluster at the United States Department of Transportation’s Transportation Research and Analysis Computing Center [1], transportation researchers can investigate complex soil-structure interaction problems. One of these problems is the stability of bridge piers during flash floods [2]. For certain riverbed soils, the high-velocity water washes away the soil covering the bridge piers, and this scour action can eventually expose the bottom of the pier and footing. In order to simulate this complex behavior, it is necessary to model the response of the reinforced concrete column – including concrete material failure – and the nonlinear soil behavior. This paper addresses some of the issues related to soil modeling. The following four material models were studied: (1) MAT005, Soil and Crushable Foam; (2) MAT010, Elastic Plastic Hydro; (3) MAT025, Geological Cap; and (4) MAT079, Hysteretic Soil. The first step in modeling the soil is to choose an appropriate model. The second step is to obtain the material parameters required by the specific model chosen. Some basic models require only a few parameters while the more complex models require many more. For site specific analysis, soil testing is required and then skilled analysts extract the needed parameters. The parameters obtained from soil test are given for the above four soil models. The hydrostatic compression response predicted by each model is compared to experimental data. The MAT005 and MAT025 materials were used in a three-dimensional SPH simulation of a rigid platen being pushed into sand.

• Effect of Thickness Changes and Friction in Thermoforming Process Simulations in LS-DYNA® for UHMWPE Unidirectional Cross-Plies

  Kari D. White, James A. Sherwood (University of Massachusetts Lowell)

  This paper discusses the use of LS-DYNA for the modeling of thickness changes and frictions of DSM Dyneema® HB210, an Ultra-High Molecular Weigh Polyethylene (UHMWPE) unidirectional cross-ply thermoplastic laminate, during a thermoforming process. The thermoforming process being investigated consists of the preform phase that transforms the laminates to near net shape ply stacks and the subsequent consolidation phase that employs pressure and heat to join the preforms into a final part. During the preform phase, interply (ply/ply) and ply/tool frictions induce in-plane tension in the sheet of thermoplastic lamina. Knowing the effective tool/ply and ply/ply frictions such that the binder force can be prescribed is critical to preventing defects such as wrinkling, waviness and tears during the preforming process. The main mode of deformation of the laminate during the preform phase of the manufacturing process is in-plane shearing of the laminate, which can lead to variations in thickness. When multiple preform layers are compressed in the consolidation phase, the compounding of the thickness variations can adversely affect the uniformity of pressure distribution between matched die tooling, resulting in inconsistent consolidation. The modeling of the preform and consolidation steps can guide design changes in the processing conditions and ply blank geometries to achieve a well consolidated part. The temperature-dependent material properties derived from shear, bending, tensile and friction tests are implemented in a LS-DYNA simulation with a discrete-mesoscopic user subroutine for the material behavior of the cross-ply laminates. Beam elements capture the fiber orientations and carry the tensile and bending loads, while shell element exhibit the shear stiffness as a function of shear angle. The effect of thickness change of the laminate is investigated through the comparison of general shell elements without thickness change to thickness stretch shell elements (Elform=25) that change in thickness due to shearing, stretching and compression. The sensitivity to tool/fabric, as well as fabric/fabric, friction is also investigated in combination with thickness changes. Single-layer and triple-layer preforms are simulated and results produced support the need for both accurate friction inputs as well as including changes in thickness in the simulation.

• Effect of Thin-walled Tube Geometry on Its Crashworthiness Performance

  Anton Kuznetcov, Igor Telichev, Christine Q. Wu (University of Manitoba)

  The present paper deals with the numerical analysis supporting the crashworthiness design of a thin-walled tube. The thickness and wall shape were parametrically changed to study their effect on the tube performance under the axial impact. Different tube geometries were evaluated based on the common crashworthiness criteria to identify the effective designs which provide the efficient energy absorption and low peak force. The applicability of selected criteria for crashworthiness design was discussed. The observations obtained in the parametric study can be used to improve the crash behavior of energy-absorbing structures.

• Effect of Triggering Mechanism on the Load-Displacement Response and Folding Pattern of Square Aluminum Tubes

  H. El-Hage, N. Zamani - University of Windsor, Canada, P. K. Mallick - University of Michigan-Dearborn, USA

  A systematic numerical investigation of the effect of triggering mechanism on the load-displacement characteristics and lobe formation of square aluminum tubes subjected to quasi-static axial compressive load is presented. Among the physical triggering mechanisms considered were chamfering, drilled holes, geometric imperfection and combinations thereof. The effect of corner radius was also considered. This study has shown that the triggering mechanism controls the load-displacement response as well as the folding pattern. Even though the folding initiation force varies significantly with triggering mechanism, the mean load does not vary greatly. The load- displacement response does not depend appreciably on the corner radius; however, the folding initiation force is lower when a rounded corner is used instead of sharp corners. The folding pattern is also influenced by the corner radius.

• EFFECTIVENESS OF COUNTERMEASURES IN RESPONSE TO FMVSS 201 UPPER INTERIOR HEAD IMPACT PROTECTION

  Arun Chickmenahalli - Lear Corporation Michigan, USA

  Analysis and development of countermeasures in meeting vehicle upper interior free motion headform (FMH) impact safety requirement (FMVSS 201) has become an important aspect for engineers. FMVSS 201 safety regulation stipulates that the Head Injury Criterion, HIC (d) should be less than 1000 when a FMH is impacted at a speed of 15 mph. The interior components of a vehicle generally do not generate high HIC (d) numbers by themselves but the steel structures behind them to which they are attached do so. The gap between the interior component and the steel structure makes a provision for the introduction of some countermeasures which can absorb the kinetic energy of the FMH in the form of internal energy so that the acceleration response of the FMH does not generate high HIC (d) and Peak G force. This paper discusses a methodology in developing a countermeasure for automotive interior components to comply with FMVSS 201 requirements. The effectiveness of introducing a countermeasure between the headliner and the steel structure or the body in white (BIW) is evaluated through Finite Element Analysis using a dynamic finite element tool, LS-DYNA. Several geometric configurations of the countermeasure have been studied to ascertain its suitability in absorbing the kinetic energy of the FMH. Parametric studies have been carried out by varying the thickness of the countermeasure to see the effect on the injury parameters, HIC (d) and Peak G. Finite element analysis results are compared with the test results as per the FMVSS 201 regulations to deduce concrete conclusions about the effectiveness of the countermeasure.

• Effects of Initial Geometrical Imperfection on Square Tube Collapse

  Liang Xue, Zhongqin Lin, Zhengxu Jiang - Shanghai Jiao Tong University

  Random geometric imperfections are natural in structures. The initial imperfections used to be ignored in structure strength analysis and thus geometric-perfect models were used in most case of numerical simulation. However, collapse of axially compressed square tubes is not such a case. LS-DYNA is used to simulate the effects initial geometrical imperfection has on square tube collapse. This study proves that dynamic progressive buckling of square box columns is sensitive to initial geometrical imperfections. The simulation results show that ideal square tubes tend to buckle in extensional mode, though is not likely to happen in experimental studies. Previous theoretical analysis suggests, that from the view of energy absorption extensional mode is a dynamic procedure of higher energy absorption characteristics than that of each of symmetric and asymmetric mode of square tube in case of high c/h. This phenomenon suggests that extensional mode is an unstable equilibrium that will easily change to another equilibrium – symmetric mode. In a real world, geometrical imperfection renders extensional mode almost unachievable for hollow square tubes. Three kinds of imperfections: deflection of wall, thickness deviation and length of section side unequal were discussed in this paper. The amplitude of imperfection was compared with the geometry tolerance. Numerical simulations are then performed using LS-DYNA. Compared with the experimental datum, deflection of wall is the main reason for the predominance of symmetric mode of axially impacted hollow square tubes. Several characteristic values with regard to the amplitude of wall deflection are discussed in particular. It is found that when the λcr , the initial impact force peak amplitude of deflection is less than a certain critical value value and the critical buckling load are almost the same and unchanged at a determined impact velocity. When deflection exceeds the critical value, buckling take place in elastic area and critical buckling force drops quickly. Energy absorbed before buckling also quickly drops to near zero when deflection is considerably large.

• Effects of Mesh Size and Remapping on the Predicted Crush Response of Hydroformed Tubes

  Guillaume D'Amours, Ahmed Rahem - National Research Council of Canada, Robert Mayer - General Motors Technical Center, Bruce Williams - University of Waterloo, Michael Worswick - University of Waterloo

  Crashworthiness simulations can be useful tools in vehicle design. According to Du Bois [1], there are many factors which affect the reliability of crashworthiness models. Especially, the mesh size and the mapping of forming results into crash models. Few studies have analyzed the mesh size effect with forming results on the crashworthiness of frame components. This paper presents an analysis of crush response of hydroformed aluminium tubes from both experiments and finite element simulations. The predicted crush response for tubes meshed with different mesh sizes for hydroforming with results transferred to the crash simulations will be firstly shown. Predicted mean crush forces will be compared to measured ones. Thereafter, forming results were remapped on a secondary model, having coarser mesh sizes for crush simulations, with the LS-DYNA option called *INCLUDE_STAMPED_PART. Results show that in certain instances, it may be better to use a fine mesh size for the hydroforming models and remap forming results to coarser mesh sizes for crashworthiness models to save computational time.

• Effects of Pre-Pressurization on Plastic Deformation of Blast-Loaded Square Aluminum Plates

  R.L. Veldman, C. Clum, J. Folkert - Hope College, J. Ari-Gur - Western Michigan University

  The effects of static pre-pressurization on the blast-induced deformation of square aluminum plates were studied both experimentally and numerically. In this study, small (0.152 x 0.152 x 0.0016 meter) clamped plates were used as a basic model of the fuselage skin of a commercial aircraft. Both un-pressurized and pre-pressurized plates (static pressure of 62.1 KPa (9.0 psi)) were considered to simulate the minimum and maximum in-flight loads experienced by a commercial aircraft due to cabin pressurization. This work extends previous research on blast loading of plates to incorporate the effects of pre-pressurization. Experimentally, a vacuum vessel system was used to apply a pressure differential to the test plate. Bare spherical explosive charges of C4 were then detonated at fixed distances from the plate. The permanent plate deformations were measured for twenty-four explosive tests that considered four different blast load cases. In addition to the experimental work, numerical predictions of the permanent plate deformations were determined using finite element analysis and the commercial software ANSYS/LS-DYNA. A comparison of plate deformations determined experimentally with those predicted with the finite element method shows good correlation. For the four explosive load cases studied, no significant change in permanent plate deformations was observed as static pre- pressurization increased from 0.0 kPa to 62.1 kPa.

• Efficiency Improvement of Seat Belt Pull CAE Analysis by Technology and Process Changes

  Ligong Pan, Sushanth Ramavath, Seung Hyun Jung, Luis Hernandez, Randall Frank, Core CAE Methods, Digital Innovation, Ford Motor Company;, Hai Truong, Core Seats & Restraints, Ford Motor Company;, Yuzhao Song, Body Exteriors, Ford Motor Company

  This work addresses the capabilities of LS-DYNA® and LS-PrePost® in reducing the run-time for quasi-static and dynamic analysis involving large models using the following commands, *DEFORMABLE_TO_RIGID_AUTOMATIC and *CONTROL_MPP _DECOMPOSITIO_TRANSFORMATION. CAE analysis of seat belt pull assessments for FMVSS regulations is often a time consuming task with each iteration running overnight. This paper describes a new methodology that significantly reduces the model run time to few hours (70-80% reduction). The new methodology allows the users to take advantage of some of the new features and control cards in LS-PrePost and LS-DYNA solver, respectively, with a negligible set-up time. These features are included in the input deck as an add-on, which will allow the user to go back to the “live-buck” (baseline deformable model) without any issues for a final verification.

• Efficient Characteristic Identification of Plastic Materials for Crash Analysis with 3-Point Bending Machine

  O. Ito, Y. Nakagawa, K. Kaneda, N. Matsuura, Y. Ueda (Honda R&D)

  According to WHO’s report, there are over 270,000 people who are involved in traffic fatal accidents [1]. Based on this accident data, the third-party assessment organization performs pedestrian protection test to evaluate a vehicle safety performance [2]. The pedestrian protection tests are evaluated for the protective performance of a head and legs of pedestrian. In particular, plastic parts such as a bumper face, a grille and head lights are evaluated by the leg pedestrian test. On the other hand, low speed crash test regulated by the United Nations evaluates a bumper protection performance (ECE42). In general, the pedestrian and bumper protection performances are in a trade-off relationship. Therefore, it has become important to balance these performances because the country which does the pedestrian protection test is increasing in recent years. In order to design these performances, it is essential to use the plastic CAE model with high accuracy. However, there are many types of characteristics for the plastic parts compared to the steel parts. It is an issue to collect the material properties for the many plastic parts in author’s development environment. Investigating the past literature to solve this issue, we found that Reithofer et al.[3] developed the machine and method to create the material property for CAE in a short time. So this study is to validate that the machine can be used efficiently to identify the material property for the pedestrian protection and low speed crash.

• Efficient Global Optimization Using LS-OPT and its Parallelization

  A. Basudhar, N. Stander, I. Gandikota (LSTC)

  Simulation-based design has evolved significantly in the past few decades. While the computing resources have advanced, model complexity has also increased considerably to capture the physics in greater detail. Therefore, reducing the number of “expensive” samples needed to obtain an optimal design is very important. Also, parallel computing has now become widely available, making the simultaneous selection of multiple samples desirable for any optimization algorithm. Efficient global optimization (EGO) has become a very popular method since the late 1990s. In this work, a constrained EGO implementation in LS-OPT v6.0 will be presented that can be used to select samples either in serial. One of the limitations of EGO, in its original form, is that it selects one sample per iteration and is unsuitable for parallelization. Different approaches to overcome this issue have been proposed, such as the Kriging-Believer, Constant Lier, as well as Pareto-based methods. However, there is scant literature pertaining to parallel sampling for constrained EGO, especially in the context of reliability-based design optimization (RBDO). The current LS-OPT implementation of EGO parallelizes the algorithm by selecting one sample per iteration using expected improvement (EI) maximization (basic idea of EGO), while the rest are selected as space filling samples. Evaluation of additional space filling samples helps in reducing the variance of the Kriging prediction globally, thereby updating the improvement function for the next iteration. In addition to the current LS-OPT v6.0 implementation, this work will also present a new Pareto-based parallel constrained EGO method for deterministic optimization and for RBDO that aims to increase the efficiency of EGO as well as to widen its scope of application, e.g. RBDO. A guidance function based on proximity to the limit state will be used in the case of RBDO. A classification method will provide the total probability of feasibility (Pfeasible) of all constraints. Pfeasible will be used as one additional objective (irrespective of the number of constraints) to define a multi-objective problem for locating the samples. One of the infill criteria in sequential constrained EGO is to maximize the product of EI and Pfeasible. However, either of the two terms may dominate the other. The proposed approach will mitigate this issue by considering the Pareto front with trade-off between the two criteria. Also, instead of treating EI as an objective, it will be decomposed in two functions (prediction mean and variance), as EI may not always balance exploration and exploitation. Examples validating the proposed method will be presented.

• EFFICIENT MODELING OF PANEL-LIKE TARGETS IN PERFORATION SIMULATION

  Guangyu Shi, Junyan Guo and Chun Lu - Institute of High Performance Computing Singapore

  This paper studies the application of thin shell elements and solid shell elements in the structural modeling of panel-like targets in finite element perforation simulations. LS-DYNA is used for the present numerical investigation. By comparing the projectile residual velocities and impact pressures given by the shell element targets to those obtained form the solid element target, this work shows that the solid shell element modeling of panel-like targets can not only save a lot of computational effort, but also be able to give good results if the target panels satisfy certain conditions. Therefore, the shell element modeling of targets is an efficient model in the performance simulation of projectiles penetrating through panel-like targets. A preliminary criterion for the validity of the shell element target model is also proposed in the paper.

• Efficient nonlinear multi-scale modeling of composite structures

  Thibault Villette, Jan Seyfarth, Roger Assaker, Laurent Adam - e-Xstream engineering

• Efficient processing method for material card definition of AHSS and UHSS to predict fracture in crash analysis and its application to vehicle crash model

  Kang Hee Lee, Dae Young Kim, Chul Woong Jun, Kyoung Teak Lee

  Crashworthiness of the vehicle body is getting importance to meet the enhancing vehicle crash safety regulations. To improve the vehicle body crashworthiness, application of Advanced high-strength steels (AHSS) and Ultra high-strength steels (UHSS) are continuously increasing due to their superior strength than conventional high-strength steels (HSS).

• Efficient Processing of Multiple Contacts in MPP-DYNA

  Brian Wainscott - Livermore Software Technology Corporation

  Complex models often contain more than just a few contact interfaces. The decomposition of such a model can result in an uneven distribution of these contacts among the available processors. Some contacts may lie wholly on a single processor, while others will be distributed across many or all of the processors. Some processors may have many contacts to handle, and others may have none. This variability can cause inefficiencies which adversely impact scalability. I will show recent work on contact algorithms in MPP-DYNA which addresses some of these issues.

• Eigensolution Technology in LS-DYNA ®

  Roger Grimes (LSTC)

  LSTC has been adding additional eigensolution technology to LS-DYNA. For several years LS-DYNA has a Block Shift and Invert Lanczos Eigensolver in both SMP and MPP implementations. But this capability did not cover the full spectrum of applications. We have supplemented the Lanczos solver with a Power Method solver for Implicit mechanic problems using the Inertia Relief Feature. As we have been adding unsymmetric modeling features through materials, elements, and contact, we have added an eigensolver based on ARPACK for such problems. Important applications for the unsymmetric eigensolver are rotational dynamics and brake squeal analysis. We are also developing an implementation of AMLS (Automated Multilevel Substructuring Method) for applications such as NVH that want hundred, even thousands, of eigenmodes quickly which are willing to have a less accurate solution compared to the Lanczos eigensolver.

• Eight-Node Solid Element for Thick Shell Simulations

  Yong Guo - Livermore Software Technology Corporation

  An eight-node hexahedral solid element is incorporated into LS-DYNA to simulate thick shell structure. The element formulations are derived in a corotational coordinate system and the strain operator is calculated with a Taylor series expansion about the center of the element. Special treatments are made on the dilatational strain component and shear strain components to eliminate the volumetric and shear locking. The use of consistent tangential stiffness and geometric stiffness greatly improves the convergence rate in implicit analysis.

• Electrochemical-Thermal-Mechanical Coupling of Lithium-Ion Battery Model in LS-DYNA®

  Kyoungsu Im, Z.-C. Zhang, and Grant Cook, Jr. (Livermore Software Technology, an ANSYS Company), Jaeyoung Lim (Hyundai Motor Group R&D Division), Kyu-Jin Lee (Myongji University)

  In this paper, we report a new development of battery-thermal-structure-interaction (BTSI) based on previously developed electrochemical Lithium-Ion models: i) a single insertion lithium metal model, and ii) a dual insertion composite model. In 10 cells of a lithium ion battery stack, each cell consists of Graphite(LiC6) anode/Separator/high performance layered LMO(LiMn2O4) or NCM(LiNi1/3Co1/3Mn1/3O2) cathode, which has been strongly proposed as a candidate for automotive batteries because of its high capacity, thermal stability, and low volume change rate (cycle performance). For the thermal-mechanical analysis, each layer in a cell and outside case are modeled corresponding to their material properties. Then, a rigid ball impacts center top position of the cell stack in order to investigate the thermal and mechanical responses of a lithium ion battery stack. To see the cell responses in different state of charge (SOC), we selected the first 20 second of the discharging processes. The results show that after the ball impact the cell stack, then the mechanical deformation started and 6 seconds after the ball compressed, a strong hot spot developed inside cell stack and the temperature increased exponentially over the melting point of the lithium, 453K. Although we demonstrated a simple impact problem to show how to simulate the electrochemical-thermal-mechanical problem, the current solver can be used to solve more practical problems such as a cellular phone drop test, notebook battery impacting test, and even deformation test of the scaled-up electric vehicle(EV) battery pack.

• Electrostatics and EM-ICFD Coupling in LS-DYNA®, a Glimpse of Things to Come

  Iñaki Çaldichoury Pierre L’Eplattenier (Livermore Software Technology, an Ansys company)

  The EM LS-DYNA solver’s primarily focus is on Electromagnetic metal forming, Inducting heating, Resistive heating. Recently, its capabilities have been extended in the domains of battery charge/discharges, electrophysiology and spot welding. However, there is a domain of applications that gets periodically inquired about and users sometimes wonder whether LS-DYNA possesses any capabilities in that area. This area would be electrostatics. As it happens, the existing resistive heating solver can be used for certain applications by proceeding with an analogy between the Poisson equation for electrostatics and the Poisson equation for resistive heating, itself a derivative of Ohm’s law. Still, electrostatics often involves the calculation of the Coulomb force which is a surface force typically acting on the parts of a capacitor and for which no option was available for the user to do a coupled EM-structure analysis. From this, the idea sprung to solve the EM fields on the same mesh as the one provided by the ICFD solver. Indeed, the ICFD solver specializes in fluid structure interaction problems and has got extensive capabilities in transferring forces from the fluid surface to the solid as well as advanced dynamic mesh movement tracking and adaptive remeshing. In this paper, the current capabilities allowing the merging of the EM and ICFD solvers will therefore be described. Going beyond the domain of electrostatics, further applications which combine the domains of electromagnetic and fluids such as Magnetic Hydrodynamics (MHD) and Magnetorheological fluid (MRF) will be discussed.

• EMAS Core Material Modeling with LS-DYNA

  Yijian (Jack) Shi - Engineered Arresting Systems Corporation

  With Lagrangian meshes and the LS-DYNA FEA explicit solver, Mat #63 – Crushable Foam is used to simulate the Phenolic foam – a candidate material for an EMAS core [7]. The simulated conditions include three scenarios: unconfined uniaxial compression, confined uniaxial compression and plate penetration into a large block. The three scenarios are purposely chosen for utilizing test data and validating simulation results. The simulations reveal that when an hourglass control is needed, the parameters for the control can significantly affect the results. The simulations with element formulations ELFORM=2 and 3 deliver better results than ELFORM=1. However, ELFORM=1 is the least expensive due to savings in computation time. ELFORM=3 is much more expensive than ELFORM=2 even with similar accuracy. When there is a symmetrical modeling condition, a reduced model size not only can save computational cost, but also sometimes can achieve greater accuracy. The simulation results are very sensitive to the value of TSC. For the very weak crushable material, a proper small value of TSC is preferred, instead of absolute zero. At extreme large deformation, the Lagrangian meshes may not work well because of extreme element distortion, which is observed in the scenario of plate penetration into a large block.

• Emphasis on Heat Affected Zone (HAZ) Modeling Around MIG Welded Joints in Crash CAE Virtual Predictive Full Vehicle Models

  S. Pethe (FCA US), M. Channegowda (Altair), S. Patil, A. Sheshadri, K. Jaboo (FCA)

  Current challenges in the auto industry are compelling virtual simulations to predict strength and rupture of MIG welded joints. Rupture prediction of such joints enhances the design and development process. In body-on-frame vehicles most metal parts are joined using MIG welds and strength evaluation of such joints are crucial to vehicle crash and safety performance. Virtual simulation capabilities with these predictions help in enormous ways to reduce cost and time involved in proto-type testing of vehicles in the product development cycles.

• Enabling Effective and Easy to Access Simulation

  E. Schnepf (Fujitsu Technology Solutions), S. Gillich (Intel)

• Enabling Interoperability for LS-DYNA Users with Envyo® using the VMAP Standard

  C. Liebold, T. Usta (DYNAmore)

  From 2017 until mid’ 2020, DYNAmore collaborated with various partners from the manufacturing industry, universities, independent research institutions, and software vendors to develop a software neutral storage format for finite element data. The goal was to define a new standard which allows for the flawless exchange of all the required information, enabling the industrial partners to easily establish closed simulation process chains for production processes, where various software tools with non-consistent data formats have been a barrier in the past. During the project, an interface between the mapping tool Envyo® and the established VMAP standard has been realized and validated with test cases.

• Enabling Productive Use of Isogeometric Shells in LS-DYNA

  Lukas Leidinger, Stefan Hartmann, Frank Bauer, Dave Benson, Attila Nagy, Liping Li, Marco Pigazzini, Lam Nguyen

  Isogeometric Analysis (IGA) [1] is a novel Finite Element Analysis (FEA) technology based on splines known from Computer Aided Design (CAD). In an isoparametric sense, IGA uses the higher-order and higher-continuity spline basis functions, e.g., Non-Uniform Rational B-Splines (NURBS), not only to describe the model geometry, but also the solution field. This may yield a more accurate geometry description, higher solution accuracy and a larger time step in explicit analysis compared to conventional FEA.

• Enabling the *CONSTRAINED_INTERPOLATION_SPOTWELD (in detail SPR3) as a general-purpose fastening element

  M. Styrnik (BMW Group), T. Erhart (DYNAmore)

  It is known that the simulation of fastening elements can be carried out by using different approaches. One common way is the use a force-displacement based approach for single-point-connections. While enabling LS-DYNA to calculate crash simulations in our crash simulation tool chain it was necessary to make several adjustments to the standard *CONSTRAINED_INTERPOLATION_SPOTWELD keyword to ensure that the currently available data can be used almost completely.

• Enabling the Analysis of Topologically Connected Multi-Patch Trimmed NURBS Shells in LS-DYNA

  S. Hartmann (DYNAmore), L. Li , A. Nagy, M. Pigazzini, D. Benson (LSTC), L. Leidinger (BMW)

  In 2005, the term “Isogeometric Analysis” (IGA) was introduced by Hughes et al. [1]. Since then, reams of scientific research work has been devoted to this new finite element technology, whose main idea is to use the same geometrical description during the finite element analysis (FEA) that was previously used during the design process in the computer-aided design (CAD) environment. The most widely used and best understood mathematical description in CAD is based on non-uniform rational B-splines (NURBS). Hence NURBS-based shell and solid finite elements have been developed and implemented into LS-DYNA over the last few years. Although NURBS-based solids are available, the remainder of the paper will exclusively focus on isogeometric shell element formulations in LS-DYNA.

• Energy Absorbing Sandwich Structures Under Blast Loading

  Dong Kwan (David) Lee, Brendan J. O’Toole - University of Nevada, Las Vegas

  A recent experimental study at the Army Research Laboratories shows that flat panels with various foam or honeycomb faceplates transferred more energy to a structure under blast loading relative to a structure without an energy absorbing faceplate. Ideally, the foam or honeycomb material should transfer less energy to the structure since it absorbs energy while it deforms plastically. Non-uniform deformation of the energy absorbing material may lead to increased pressure on the panel, causing kinetic energy transfer to the plate. One objective of this work is to simulate the non-uniform response of the honeycomb panel subject to blast loading. Most of the work involves an investigation into the optimum design of the honeycomb structure for energy absorption during blast loading. In this paper, only a square-celled honeycomb structure is studied. Variables under investigation for this paper are the core and face sheet thicknesses of the honeycomb sandwich structure. Results of a DOE study are attained, which evaluate the relative contribution of panel variables to energy absorption. Also, the results of a preliminary optimization study are discussed along with some of problems faced during this study.

• Energy-Absorbing Wheel Tethers for Racecars

  Brian A. Coon - M.S.C.E., E.I.T., John D. Reid - University of Nebraska-Lincoln

  Wheel tethers are frequently used on racecars to prevent detached wheels from flying freely away from the car and injuring spectators. Extremely stiff tethers may cause the wheel assembly to be either yanked back toward the car, putting the driver in danger or to be snapped free at an uncontrolled trajectory, exposing spectators, other drivers, and workers to danger. Conceptual design of energy absorbing wheel tether systems was performed using the finite element program LS- DYNA. Two major approaches to energy absorption were explored, both of which involved metal bending. For absorbing energy through sheet metal bending, parametric studies showed that a minimum of 4 through-the- thickness integration points were required to capture good elasto-plastic behavior of shell elements. Additionally, for absorbing energy through solid tube bending, it was found that a circular cross-section in elasto-plastic bending must be modeled with a minimum of 12 solid elements in the cross-section. The developed tether design was able to absorb a total of 10 kJ of kinetic energy from the wheel assembly. This amount of energy is equivalent to reducing the trajectory height and distance of a 68-kg w

• Engine Impeller Sub-Fragmentation Simulation Using EFG Method

  Shoufeng Hu - Hamilton Sundstrand, C. T. Wu, Yong Guo - Livermore Software Technology Corporation

  Engine impeller burst containment test may lead to the impeller sub-fragmentation. The containment of the impeller debris from sub-fragmentation presents a new challenge, because of the unpredictable pattern of dynamic fracture. In this study, the capability of EFG failure method in predicting the dynamic fracture of the ductile material, used for the engine impeller under impact loading, is demonstrated. In the EFG method, the combination of fast transformation method and meshfree visibility approach with cohesive fracture is proven to be an efficient way to model the progressive fracture in a general three-dimensional problem. In this study, the Mode-I fracture is adopted and the crack is assumed to propagate cell-by-cell in the direction of maximum principal stress. The meshfree visibility approach is introduced to impose the strong-discontinuity in the meshfree approximation as well as to compute the displacement jump in the initially rigid cohesive model.

• Engineering Analysis with Finite Elements - LS-DYNA for Undergraduate Student

  J. D. Reid (University of Nebraska-Lincoln)

  A typical college course in finite elements consists of learning the method in continuum mechanics (transient heat conduction and elastic stress analysis), from formulation of the governing equations to implementation in some software (such as Fortran or Matlab). This class is not such a course. Instead, this class concentrates on analyzing engineering systems; a challenging task regularly done by design engineers. Finite elements is the tool of choice for performing such analysis for many, many applications and corporations. Structural stress, heat transfer, fluid flow, and modal analysis are quite distinct from each other but can all be treated successfully with finite elements. Of course, some basic principles of the finite element method is required, as well as understanding of behavior, sensitivity and robustness relative to mesh density, boundary conditions, material properties and other influential parameters. But the emphasis is on the engineering analysis itself, not the tool. LS-DYNA is well suited for this endeavor because of its’ multi-physics capabilities.

• EngineeringBrochure.pdf
• ENHANCED FAILURE PREDICTION IN SHEET METAL FORMING SIMULATIONS THROUGH COUPLING OF LS-DYNA AND ALGORITHM CRACH

  Gernot Oberhofer, Harry Dell, Dmitri Dell, Helmut Gese - MATFEM

  In sheet-metal-forming the forming limit curve (FLC) is used for ductile sheets to predict fracture in deep drawing. However the use of the FLC is limited to linear strain paths. The initial FLC cannot be used in a complex nonlinear strain history of a deep drawing process or a successive stamp and crash process including a significant change in strain rate. The CRACH software has been developed to predict the forming limit of sheets for nonlinear strain paths [1]. It has been validated to predict instability for bilinear strain paths with static loading in the first path and dynamic loading in the second path for mild steels [2]. As the postprocessing of strain paths from single finite elements in CRACH is not economic for industrial applications MATFEM initiated a project to couple CRACH directly with FEM-Code LS-DYNA using a user- defined material model. This allows a prediction of possible failure during the simulation for all elements with respect to their complete strain history. A special strategy has been developed to include CRACH without extensive increase in total CPU time. The developed interface to LS-DYNA allows also the implementation of other failure criteria demanding the history of deformation like for example a tensorial fracture criterion. In order to test the reliability of the calculated safety factor experimental tests for bilinear strain paths have been simulated [2]. In this case the experimental and numerical investigations have been made on two-stage forming processes (static in the 1st stage and both static/dynamic in the 2nd stage) . The static-static case should simulate a stamping process with bilinear strain path. The static-dynamic case should simulate a successive stamp and crash process. The simulation of a complex deep drawing problem including areas with significantly nonlinear strain paths has been simulated with LS-DYNA/CRACH-coupling. It can be shown that the prediction of CRACH can differ significantely from a “standard” prediction based on the initial FLC. The coupling of LS-DYNA and CRACH showed the potential to predict possible fracture in deep drawing and crash loading at an early design stage and allowed to optimise geometry and material quality to significantly reduce later problems in real components.

• Enhancement of Deformation Sub-Model in an Orthotropic Material Model

  Loukham Shyamsunder, Bilal Khaled, Subramaniam D. Rajan (Arizona State University), Kelly S. Carney, Paul DuBois (George Mason University), Gunther Blankenhorn (LSTC)

  A generalized tabulated three-dimensional orthotropic material model currently available in the dev version of LS-DYNA® as MAT_213 is enhanced with new features. MAT_213 has a modular constitutive model architecture consisting of deformation, damage and failure sub-models. The deformation sub-model has been enhanced with visco-elastic-plastic formulation with rate and temperature dependencies as well as strain-smoothing techniques to improve the stability of the analysis. Verification tests are carried out with experimentally obtained stress-strain curves at quasi-static and at higher rates of loading for the T800-F3900 unidirectional composite. Validation tests are carried out using data from high-speed projectile impacts on stacked-ply composite panels. Results show that the developed framework provides reasonable predictive capabilities.

• ENHANCEMENTS IN DUMMY MODEL DEVELOPMENT AND OUTLOOK

  Jim Rasico, Fuchun Zhu - First Technology Safety Systems, Inc., USA, Robert Kant, First Technology Safety Systems Europe, The Netherlands

  It has been almost 11 years since FTSS introduced the Hybrid III 50th dummy finite element model in 1996. From their inception, Finite Element dummy models were constrained in size and accuracy by the computational resources and modeling capabilities of the time. In recent years, the numerical simulation and analysis industry has benefited from the advanced computing technology and finite element modeling techniques. Today the latest technologies are being utilized to further improve the dummy model accuracy, and stability. A key requirement for new models is to achieve a level of geometric accuracy unattainable a decade past. The new CAD data source for FE models is derived from 3-D laser and X-ray scanned geometry to ensure the accurate representation of hardware geometry both externally and internally. New material testing is being utilized to compliment existing data sets and allow for the replacement of simple material models with more complex/realistic definitions. Experiments with oblique loading conditions have been designed to further enhance the FE model. This data will allow validation in conditions experienced by many dummy model users. Additional tests will be carried out to examine different impact pulses to attain the highest level of dummy model performance verification. These advanced technologies are being implemented in the dummy models to further improve their quality.

• Enhancements in dummy model development and outlook

  Jim Rasico, Fuchun Zhu, Robert Kant - First Technology Safety Systems, Inc.

  It has been almost 11 years since FTSS introduced the Hybrid III 50th dummy finite element model in 1996. From their inception, Finite Element dummy models were constrained in size and accuracy by the computational resources and modeling capabilities of the time. In recent years, the numerical simulation and analysis industry has benefited from the advanced computing technology and finite element modeling techniques. Today the latest technologies are being utilized to further improve the dummy model accuracy, and stability. A key requirement for new models is to achieve a level of geometric accuracy unattainable a decade past. The new CAD data source for FE models is derived from 3-D laser and X-ray scanned geometry to ensure the accurate representation of hardware geometry both externally and internally. New material testing is being utilized to compliment existing data sets and allow for the replacement of simple material models with more complex/realistic definitions. Experiments with oblique loading conditions have been designed to further enhance the FE model. This data will allow validation in conditions experienced by many dummy model users. Additional tests will be carried out to examine different impact pulses to attain the highest level of dummy model performance verification. These advanced technologies are being implemented in the dummy models to further improve their quality.

• Enhancements to Implicit Mechanics

  R. Grimes, R. Lucas, C. Weisbecker, C. Ashcraft, F. H. Rouet, J. Anton (LSTC)

  Solving large sparse linear systems of equations is often the computational bottleneck for implicit calculations. The team of developers at LSTC is working on many aspects of this linear algebra. This is the first of two talks describing this body of work. While the second talk will focus on the performance of the distributed memory linear equation solver, this talk will focus on other aspects of the overall solution process, often those directed by the user. This includes reordering to reduce the storage and operations required by the default multifrontal linear solver and our progress on a distributed memory parallel ordering package. We also discuss alternative solvers that LSTC is considering such as MUMPS and iterative soltuion. Finally, we will describe enhancements to the user interface making implicit mechanics easier to use. In addition we will give a update on new features for implicit including implicit linear multiple load analysis and other user requested features.

• Enhancing Vehicle Safety Assessments through Advanced Virtual Testing Crashworthiness with the aid of ANSA and META

  Thanassis Lioras, Thanassis Fokylidis, Ioannis Stavrakis, Nikos Tzolas

  The automotive industry is continually evolving to meet stringent safety standards and enhance occupant protection in crash scenarios. With Euro NCAP supplementing far-side impact testing with Virtual Testing Crashworthiness (VTC) starting in 2024, real tests and CAE simulations come closer more than ever. The VTC protocol mandates the use of simulation and physical test data to robustly evaluate far-side impact protection, requiring detailed compliance with validation and quality criteria, as well as specific data formatting for submission. Consequently apart from far-side more protocols will be implemented in the virtual testing raising more challenges to the safety engineers. As a result there is an increasing need for efficient tools that streamline the assessment process offering ‘know how’ of the different protocols and simultaneously minimize the human interaction with the aid of automation.

• Ensuring conformity and high level productivity between ANSA and LS-DYNA during model and load case development

  Andreas Fotiou, Thanassis Fokylidis, Lambros Rorris, Emmanuella Baksiova, Ioannis Fourkiotis

  Simulations have been playing an increasingly significant role in developing Computer-Aided Engineering (CAE) models over the last decades. Virtual testing has become standard practice in the design process, with analysts striving to establish robust procedures to validate the final products. ANSYS LS-DYNA has become a leading solution in CAE simulations, proving indispensable for engineers. Simultaneously, the BETA CAE pre-processor ANSA offers a comprehensive solution for model building, load case definition, and generating the deck file for ANSYS LS-DYNA. This ensures full conformity with ANSYS LS-DYNA standards, facilitating easy setup and high-quality results. This presentation demonstrates ANSA's capability to handle all needs of a CAE engineer in a broad spectrum of use cases ranging from ID handling and solver deck file conformity up to high level inspection and editing of a complex crash model.

• Equivalent Drawbead and its Application in Optimization of Autobody Forming Process

  Xionghui Zhou, Ziqiang Liu, Zijie Zhang, Junyue Zhang - Shanghai Jiao Tong University

  In this paper, the effect of drawbead on autobody panel forming and the theory of equivalent drawbead are discussed. Compared with the effect of real drawbead, the feasibility and essentiality of equivalent drawbead model in process optimization and finite element analysis of sheet forming are pointed out. An example of car inner door panel is presented. By means of eta/DYNAFORM software, a LS-DYNA based sheet metal forming simulation package, defects of the current process are found, and an optimized process is given.

• Equivalent Energy Method for Welding Structure Analysis

  T. Loose; J. Rohbrecht (DynaWeld)

  Simulation means real physical processes are calculated on computers with numerical methods. The real world is substituted by a virtual world. The benefits on welding are: - predict the state before manufacturing - complex high costly physical tests are replaced by low costly virtual tests, - visualization of states of work pieces, which are not or hardly able to be measured, - automation of analysis and evaluation, which cannot be realized by physical tests, - explanation of formation processes as basis for the design of optimization tasks, - training and education. Simulation for welding starts before more than 20 years [1, 2, 3] and is meanwhile in use for all welding processes. Experience has to be elaborated for new materials, new processes or new design. Welding simulation helps to achieve this experience rapidly [4, 5]. Two topics are required for industrial applied welding simulations: - The simulation has to be performed economically. - The setup of the simulation has to be founded on process data. The welding procedure specification (WPS) contains all data relevant for the welding process. This paper explains how to use this information as input for a welding Large simulation models as well as thick parts with multilayered welds leads to a special challenge. Welding simulation for this kind of specimens becomes economic only under use of simplified approaches: the metatransient method for 3D or 2D models. The authors developed the equivalent-energy-method (EEM) which is based on the data from the WPS. This method postulates that the energy input per unit length in the simplified model is the same than in the detailed model. Additionally a temperature field calibration guarantees for the simplified method, that the heating of the area next to the weld, which is mainly driving the distortion, is estimated correctly.

• Ergonomic optimization of rowing seats using personalized Human Body Models

  Manuela Boin

  Seat-related discomfort and health problems, which occur especially during long rowing tours or training sessions, can be reduced by rowing seats with a surface geometry that is ergonomically optimized for the particular rower. This seat optimization can be done by analyzing measured pressure distributions and modifying the standard seat surface geometry for a specific person based on these results using CAD tools. The project presented here focuses on the purely virtual development of the optimal geometry for specific rowers. FE simulations were performed using Human Body Models (HBMs) to define seat geometries for specific individuals.

• ES-2/re Model Validation on FAA Requirements for Aircraft Side Impact with LS-DYNA®

  Alexander Schif, Yupeng Huang, Sebastian Stahlschmidt (DYNAmore GmbH)

  For many years ES-2 and ES-2re dummy models are used in car side crash simulations. The use of the ES-2 and ES-2re dummy models in these simulations is precisely defined. Until recent work in the aerospace industry within Aerospace Recommended Practice (ARP) 5765 Revision B by SAE International (SAE) there were no instructions available for the exact use of the ES-2 and ES-2re dummy. SAE ARP 5765 Revision B aims for an easier seat certification process to fulfill Federal Aviation Administration (FAA) requirements giving best practice advice of how to work with ES-2re in side facing impact aircraft simulations. In connection with SAE ARP 5765 Revision B new side facing sled tests were performed by the FAA with special pulses. Based on these new side facing sled tests the DYNAmore ES-2 and ES-2re model was further validated to meet these new demands. With the end of the validation process the ES-2 and ES-2re V8 model, suited for car and aircraft side crash simulations, was released. Besides much better performance in the ARP side facing sled tests, also the overall performance of the already existing Partnership of Dummy Technology and Biomechanics (PDB) car side facing sled tests was increased. To support the visualization of the increasing performance of the ES-2 and ES-2re dummy CORA ratings were created for the last three release versions of ES-2 and ES-2re. The ratings are available for the new FAA sled tests, the PDB sled tests and all the certification tests of the dummy.

• Estimation of Spot Weld Design Parameters using Deep Learning

  A. Pillai (TU Dresden), M. Thiele (SCALE), Prof. U. Reuter (TU Dresden)

  In automotive production, each automobile has approximately 7,000 to 12,000 spot welds along with other kinds of connections. The position of the spot weld with respect to the flange and the distance between the spot welds as well as various other parameters usually vary for each part combination (spot weld design). If these properties are known, they can be used for automatic generation of spot welds during the design phase of the product development which is otherwise a cumbersome manual process. The spot weld design to be determined by the engineer depends on many factors (input parameters) such as loads and forces that might be applied to the structure, material combination, geometry of the parts, connection technology and its process parameters. Some of these parameters such as material combination and geometry of the parts are predefined by the designer or are results of the circumstances such as loads and forces applied at the connection. The remaining parameters such as connection technology, process parameters, spot weld distances and flange distance have to be chosen by the engineer. On the basis of existing designs and with help of machine learning techniques it may be possible to predict the spot weld design parameters like spot weld distance and flange distance. Within this work existing spot-weld designs are extracted from a vast amount of FEM simulation input data available in the Simulation Data Management (SDM) system LoCo of SCALE GmbH and applied as the basis for training and benchmarking new methods for estimating spot weld parameters.

• Estimation of Stress Triaxiality from optically measured Strain Fields

  S. Conde, F. Andrade, M. Helbig, A. Haufe (DYNAmore), M. Feucht (Daimler)

  Nowadays, strain fields can be experimentally measured with high accuracy through digital image correlation (DIC). This kind of measurement is becoming standard when it comes to physical testing of materials. The information from such measurements is then often used in the calibration and validation of material cards to be later used in LS-DYNA. Especially regarding the prediction of failure, the experimentally measured strain fields can be quite helpful. Among several methods for the calibration of material cards, one method relies on the direct use of such strains in the definition of the failure curve as a function of the stress triaxiality ratio. However, in such method, the triaxiality is usually estimated from the simulation of the specimens adopted in the physical tests or, sometimes, it is estimated from analytical calculations based on the loading type and on the geometry of the specimen. It is however widespread known that the triaxiality typically varies during experiments. Therefore, it would be interesting to observe the evolution of the triaxiality throughout the physical test. As mentioned before, the typical way of doing this is through the use of numerical simulation to perform this task. In this paper, we concentrate efforts in developing a method to estimate the triaxiality distribution and evolution using information directly from the DIC measurement. To that end, a plane stress state is assumed and the strain ratio is calculated from the measured strains. The stress triaxiality ratio is, in turn, a relation between the hydrostatic and the equivalent stress. Therefore, in order to calculate the triaxiality from the strain field, a relationship between the strain ratio and the triaxiality has to be defined. This is only possible through the consideration of a constitutive (i.e., material) model. Typically, the J2-based plasticity model (commonly known as the von Mises model, e.g., *MAT_024 in LS-DYNA [1]) is used for this kind of task. However, our research on the topic has shown that this assumption may lead to wrong triaxialities even in cases when the triaxiality is known beforehand, for instance, in a uniaxial tensile test before necking. This error can be significantly reduced if the anisotropy of the material is also taken into account. To that end, we use a Hill-based transversely anisotropic material law in order to consider the effect of the anisotropy. After some mathematical derivations under the assumption of plane stress, negligible elastic strains and proportional loading, it is possible to find a closed-form relation between the strain ratio and the triaxiality including the effect of the R value. The results for an aluminum sheet show that the triaxiality is much better predicted using the new formula. Using a software dedicated to the evaluation and visualization of optically measured strain fields, it should be possible to plot triaxiality fields from experimental data that can be later used either for the calibration or validation of a material card. Furthermore, this novel technique can also be employed on the development of new specimen geometries in order to better assess the stress triaxiality ratios obtained with the new geometry without having to first calibrate a material card for that.

• ESTIMATION OF THE TRANSVERSE CRUSH RESISTANCE OF A SECTION OF THE T23 FRIGATE

  Dr. G.S. Kalsi - Cranfield University, UK

  Ocean-going vessels are very complex structures, and can have displacements ranging from hundreds to tens of thousands of tons. In the case of bulk carriers and tankers, this can be as much as half-a-million tons. When in motion, they can possess very large amounts of kinetic energy even if their velocities are small. They therefore have the potential to cause serious damage in case they are involved in a collision. Ships moving in ports or harbours often move in limited space and there is always the possibility that an accidental collision may occur, albeit at a low velocity. If either the striking or struck ship carries sensitive or hazardous materials then the consequences of a collision may be far more serious than that consisting simply of structural damage to either ship. One way of reducing potential damage to ships carrying such cargo is to restrict the travel velocities of approaching ships to some limiting values. The reliable estimation of such velocities needs as a minimum a knowledge of the crush characteristics of at least the target vessel, and preferably that of the striking vessel too. The situation addressed in this paper is one where a moored vessel, a T23 frigate, is struck normally by a similar moving vessel. It is required to estimate the crush characteristics of the struck vessel around the chosen impact location. A knowledge of the crush characteristics can then be used to derive limiting approach velocities in order to minimise damage, intrusion, etc. in the struck vessel. A three-dimensional mesh of the struck section of the moored ship has been modelled using finite elements. The implicit algorithms in LS-DYNA3D(1) were used to simulate the crushing of this ship section. The paper presents the method of analysis and the derived crush characteristic, which is then used to estimate limiting velocities for an approaching vessel

• eta/VPG: A Virtual Crash and Safety Environment for FMVSS and ECE Standards

  Akbar Farahani, Arthur Tang, Tim Palmer, Zubair Uddin - Engineering Technology Associates, Inc.

  Vehicle manufacturers, in an effort to reduce costs and meet the demand of customers are constantly reducing product development time. At the same time we see more regulations from governments, primarily aimed at vehicle safety. In additions there are variations in global regulations, such as ECE and FMVSS regulations. In order to meet the objective of reducing time and costs, manufacturers are forced to rely more and more on the virtual prototype to avoid the time and cost of constructing and testing prototypes, and to gain the insight necessary to make the current vehicle design better than past products in the area of performance and efficiency. These, in the minds of the engineering community, may be contradicting objectives. We have less time to perform more analyses, and not only that, but more critical analyses which may have more impact on the success of the vehicle when compared to the commercial impact of the analyses performed 5-10 years ago. The automotive industry is legally required to design vehicles to meet the Federal Motor Vehicle Safety Standards (FMVSS) or ECE/EEC Homologation Regulations as well as Corporate/Industry Standards. These standards are ever-increasing due to consumer awareness and the industry focus on vehicle safety, resulting in a conflict – we are increasing the simulation workload, and shrinking the time available to perform the analysis. Therefore, there exists a need to streamline all routine processes, and gain maximum efficiency from the engineer’s limited time. This paper describes the development of a set of tools which enable engineers to automate many routine crash and safety analysis tasks, gaining efficiency, accuracy and productivity.

• Evaluation of a dummy design by using a human body model

  Christian Gehre, Norbert Praxl (PDB), Sebastian Stahlschmidt, Dirk Freßmann (DYNAmore GmbH)

  Human body models for occupant protection became popular in the last years. They started to turn from high sophisticated research tools to reasonably applicable tools to support some specific areas of occupant safety. This study is focused on the evaluation of the BioRID-II shoulder design by using the THUMS human body model. After the introduction of the BioRID-II into several test protocols to assess whiplash associated disorder, some serious concerns about the dummy’s performance emerged. Various simulations and tests indicated that the dummy’s shoulder design may cause unrealistic loads. Simulation runs with the THUMS in the same test environment were used to verify this assumption. The overall kinematics and therefore the accelerations of human body model and dummy model correlate well. A comparison of forces and moments between both is difficult because of the completely different internal structure of human and dummy. However, in-depth analyses showed that the simple dummy shoulder causes direct neck loads, while a human shoulder distributes the load through clavicles and scapulas to the whole rib cage. The same artefact was observed at the recently developed model of a female rear impact dummy (EvaRID) that is based on the BioRID-II design. The THUMS was scaled down to the size of the EvaRID by keeping almost same relative differences in size as observed between BioRID-II and THUMS. The dummy artefact could be verified with the downscaled THUMS, too. In summary, a human body model is a complex, not easy to handle but helpful tool to evaluate the performance of crash test dummies and to identify dummy related artefacts. While the overall kinematics between dummy and human model are somehow comparable, forces and moments may differ because of the different internal designs of dummy and human body model.

• Evaluation of Advanced Element Formulations for Failure Prediction of Highly Complex 3D-Printed Parts

  S.Mohapatra (Sabic)

  Additive manufacturing has moved beyond rapid prototyping and is now starting to be used for manufacturing of functional parts such as in aircraft engines and medical transplants. This has resulted in a paradigm shift in design requirements for 3D printed parts from simply aiding in rapid physical visualization of designs to sustaining operating loads. Furthermore, along with the functional load bearing requirements, 3D printed designs should demonstrate benefits of lower weight and cost which are possible through innovative shapes often arrived at through detailed topology optimization. However, these innovative shapes often offer significant challenges in predictive performance evaluation due to their geometric complexity. This is amplified for structures where failure prediction under operating environment is a part of the design process such as in automotive applications. Typically, explicit solvers such as LS-DYNA are used to predict highly non-linear events such as component failures. However, the highly complex shapes arrived through topology optimization and manufactured through 3D-printing process are extremely cumbersome to model with traditional elements used in explicit solvers which are hexahedral in shape. On the other hand, tetrahedron elements can model such shapes with considerable ease, but are avoided in classical explicit analysis methodology due to loss of simulation accuracy. LS-DYNA has recently introduced higher-order tetrahedron elements which has the potential to reduce the loss of accuracy while holding onto the ease of modeling. But this benefit comes with a significant increase in simulation time due to the higher order integration approach. This paper deals with evaluation of the suitability of higher order tetrahedron elements to model highly complex shapes typical of additive manufacturing process for failure prediction of a highly complex 3D-printed specimen part representing a commonly used structural element. The predictions are compared with actual physical test results which point to satisfactory performance of the element formulation for such use. Additionally, recommendations are made to improve the material property specifications from 3D-printing material suppliers to further improve the simulation fidelity.

• Evaluation of Aircraft Structures Crashworthiness Behavior using Finite Element Analysis

  C. Zinzuwadia, G. Olivares, L. Gomez, H. Ly, H. Miyaki, Wichita State University, National Institute for Aviation Research, Computational Mechanics Laboratory, Wichita, KS 67260-0093

  Despite ongoing worldwide research and discussion regarding broad aspects of airplane crashworthiness, no specific dynamic regulatory requirement currently exists. However, the Federal Aviation Administration (FAA) requires an assessment of each new aircraft model to ensure that the airplane crash performance will not significantly deviate or otherwise degrade from typical dynamic characteristics found in previous designs [8]. The increased use of composite airframe structural components warrants a new assessment to ascertain whether the crashworthiness of the associated dynamic structural response provides an equivalent or improved level of safety compared to conventional metallic structures. Generally, this assessment includes the evaluation of the survivable volume, the retention of items of significant mass, deceleration loads experienced by the occupants, and occupant emergency egress paths. Keeping these requirements in mind in order to design, evaluate, and optimize the crashworthiness behavior of composite structures necessitates development of analytical methods and predictive computational tools. With that objective, NIAR used LS-DYNA® to develop a numerical model of the Boeing 737 10-ft section, as drop tested by the FAA. The 10-ft fuselage section geometry and material properties were reverse-engineered using repair manuals, design books, and documentation provided by the FAA. The FE model followed NIAR methodologies and mesh quality criteria. The occupants and seats were represented using mass elements. Items of mass such as lifting fixtures, camera mounts, reinforcing beams, and overhead bins were represented using finite elements. Additionally, the luggage was also incorporated into the FE model, and several studies were performed in order to accurately represent its aggregate mechanical properties. During the validation process, it was found that some geometry simplifications did not provide an adequate level of correlation. Thus, the sensitivity of increased accuracy in the geometric representation was also studied in order to provide guidance on the minimum geometric features necessary to capture the event. The final 10-ft fuselage section model was validated by comparing floor accelerations and velocities, as well as fuselage permanent deformations. A good level of correlation was obtained from this analysis, which shows that numerical methods can be used to support the design and certification of future aircraft structures for crashworthiness evaluation.

• Evaluation of ATD Models for Simulating Occupant Responses under Vertical Impact

  Ming Cheng, Doug Bueley, Lock-Sui Chin, Jean-Philippe Dionne, Neil Wright, Aris Makris (Med-Eng Holdings, LLC)

  In addition to traditional threats to vehicle occupants from frontal crash and side impact, passengers of military vehicles can also be subjected to vertical shock loading on their thoraco-lumbar spine and legs arising from the detonation of roadside bombs or landmines. In such explosion events, the vehicle hull is subjected to high level transient momentum loading, resulting in an acceleration impulse that transfers to the occupant through the vehicle floor and the seat. When conducting experimental blast testing, full-scale anthropomorphic test devices (ATD) are used to evaluate the survivability potential of passengers. Equivalent investigations involving ATD models are also conducted numerically. However, existing ATD numerical models have been developed mainly for frontal crash and side impact simulations, and have not been validated against vertical impact loading experienced by military vehicle occupants. The purpose of this paper is thus to compare blast loading results obtained with several ATD numerical models in a representative scenario. As a baseline, a simple drop test was experimentally conducted with a 50th percentile male ATD sitting on a platform, to simulate the vertical impact from a blast. Through the use of this simple structure, uncertainties arising from complicated seat and test fixture structures were avoided. During the test, the assembly consisting of the ATD and platform was placed in a controlled drop tower facility to generate an impact pulse on the ATD. The pelvis acceleration, lower lumbar force, and neck force were recorded. Simulations of this test were then performed with LS-DYNA® using different numerical ATD models. It was found that none of the numerical ATD models investigated could generate accurate enough responses, when compared to the experimental test with the physical ATD model. To extend observations from the above comparisons to more practical loading scenarios, blast off test simulations were also conducted and the results were compared with the signals recorded in an experimental blast off test. It is thus concluded that further enhancements to numerical ATD models are required for simulating occupant responses under vertical loading.

• Evaluation of Blast Mitigation Capability of Advanced Combat Helmet by Finite Element Modeling

  S. Sharma, R. Makwana, L. Zhang (Wayne State University)

  Primary blast wave induced traumatic brain injury and posttraumatic stress disorders have been observed in great number among military personnel in the recent Iraq and Afghanistan wars. Although combat helmets provide good protection against blunt/ballistic type threats, the current issue with military helmets is protection concerning the threats from primary blast wave. This study focused on investigating how combat helmets influence the blast- induced biomechanical loads in the human brain. Multi-Material Arbitrary Lagrangian Eulerian method was applied to simulate the wave propagation in the shock tube, the interaction of the shock wave with the human head, and the subsequent blast overpressure transformation through the head. The finite element model (FE) of Wayne State University shock wave generator (WSUSG) was developed and validated against experimentally measured side-on pressure time histories within the tube. Validated 3-D FE models of the human head and Advanced Combat Helmet (ACH) reported previously were used to predict the internal brain responses and assess the performance of the helmet in mitigating shock wave of various severities generated by WSUSG. Effectiveness of helmet with respect to various head orientations to oncoming shock waves was also evaluated. Biomechanical response parameters including the peak brain pressures and strains at various regions of the brain were calculated and compared between the heads with and without helmet. Wearing ACH was found to mitigate the intracranial pressures up to 33% at given blast loading conditions. The peak brain strain was reduced by 13-40% due to the use of helmet. In generally, ACH exhibited increased protective performance as the shock intensity increased. The current ACH helmet design offered superior protection to the brain in sideways blast than that in forward blast loading condition of same severity.

• Evaluation of Debris Modeling Technique on Failure Simulation of Concrete Structures

  S. Tokura (Tokura Simulation Research); K. Niwa (Terrabyte)

  It is a crucial issue to protect important buildings, especially nuclear power plants against large natural disaster or terrorist attack. Nuclear power plant is a concrete structure and highly accurate prediction of the failure modes, e.g., crack propagation, penetration and spalling is required at the impact of projectile. In reality, when concrete material is failed, the failed material is not deleted and piles up as debris instead. In the case of second impact or subsequent seismic load, existence of debris cannot be ignored since the impact force is loaded on the structure through the debris. Although many sophisticated failure models are implemented in LS-DYNA, the generation of the debris cannot be simulated when the failure models working with erosion capability are used since the failed elements are deleted. In contrast, *DEFINE_ADAPTIVE_SOLID_TO_SPH/DES keyword provides the simulation technique considering the effect of the debris since the failed solid elements are replaced with the particles. In this presentation, more realistic post-failure behavior of the concrete structure using *DEFINE_ADAPTIVE_SOLID_TO_SPH/DES is shown and the application of this capability to the real problem on concrete structure is discussed.

• Evaluation of Different Thermo-Viscoplastic Material Models under Simultaneous Hot/Cold Forging Conditions

  M. Nahrmann, P Kühlmeyer, A. Matzenmiller (Universität Kassel)

  The simultaneous hot/cold forging is an innovative metal forming process, which takes advantage of low forming forces in heated parts of the workpiece respectively high geometric accuracy in cold forged areas. For the finite element analysis of such processes, material models are required that take temperature and rate dependent plasticity into account. The material models *MAT_BAMMAN and *MAT_EMMI are available in the material library of LS-DYNA and represent the thermo-viscoplastic characteristics of metals. Furthermore, a user defined material model is implemented into LS-DYNA using the keyword *MAT_USER_DEFINED_MATERIAL_MODEL. The constitutive equations of the user material model are based on an enhanced concept of rheological models, which allows a straightforward interpretation of material behavior. Each material model describes temperature dependent nonlinear isotropic and kinematic hardening, thermally activated recovery effects as well as strain rate sensitivity. In this contribution, the aforementioned thermo-viscoplastic material models are evaluated under simultaneous hot/cold forging conditions. Therefore, the material parameters are identified with test data of the low alloy steel 51CrV4, the case-hardening steel 16MnCr5, the low carbon steel C15 as well as the aluminum alloy AlMgSi1 by using LS-OPT. The prediction accuracy of each material model is evaluated comparing the simulation and test results on the basis of the mean squared error. Due to the conditions of simultaneous hot/cold forging, the temperature ranges from room temperature up to nearly the melting point. In forging processes, the mutual interaction of the displacement and the temperature field effects a thermo-mechanical coupled problem, which is solved by the staggered solution scheme in LS-DYNA.

• Evaluation of Kinematic Hardening Models for Multiple Stress Reversals under Continuous Cyclic Shearing and Multi-Step Bending

  S. Suttner, M. Rosenschon, Prof. M. Merklein (University of Erlangen-Nürnberg)

  In complex sheet metal forming processes the material undergo es various strain path changes, for instance, during the passing of a drawbead or a radius. Based on the Bauschinger effect that describes the material’s specific decrease of the yield stress after a load reversal, the resultant hardening behavior significantly differs from that o f a monotonic loading condition. For a reliable numerical process design, especia lly in springback analysis, a consideration of this effect is essential. Within this contribution , the evolution of the material behavior under cyclic loading is investigated with consecutive cyclic shearing of DP - K54/78+Z in a modified ASTM shear test. Mo reover , the kinematic hardening models according to Chaboche - Rousselier and Yoshida - Uemori are identified. In this context , the influence of the yield criterion and the capability of the different hardening models are analyzed. The applicability of the ide ntified parameters is finally evaluated in a multi - step bending process.

• Evaluation of LS-DYNA Material Models for the Analysis of Sidewall Curl in Advanced High Strength Steels

  A. Aryanpour, D. E. Green (University of Windsor)

  Accurate modelling of the Bauschinger effect and anisotropic plasticity in advanced high strength steels (AHSS) is essential in order to accurately predict sidewall curl. In this study, the performance of several constitutive models from the LS-DYNA library was evaluated for the prediction of sidewall curl in a plane-strain channel draw process for two grades of AHSS (TRIP780 and DP980). Since the profile of the channel section after springback results from the recovery of elastic strains in a plastically deformed sheet metal, the stress distributions in the channel section after the forming stage were carefully examined. Deformation modes in the sheet metal included sliding under the binder pressure, successive bending-unbending through a drawbead and drawing over the die entry radius. Material types 24, 36, 37 and 125 were used with shell element formulation 16 in order to select the most accurate combination for predicting sidewall curl. An investigation of simulation results showed that MAT125 predicted the sidewall curvature more accurately than the other models.

• Evaluation of LS-DYNA® Corpuscular Particle Method – Passenger Airbag Applications

  Chin-Hsu Lin, Yi-Pen Cheng, General Motors

  A uniform pressure method, i.e. no pressure variation on bag surface and location, in LS-DYNA has been commonly used to simulate airbag deployment and interaction of airbag with the occupants. Another newly developed LS-DYNA CPM (Corpuscular Particle Methodology) has gained recognition and acceptance recently because it considers the effect of transient gas dynamics and thermodynamics by using a particle to represent a set of air or gas molecules and then a set of particles to represent the entire air or gas molecule in the space of interest. This LS-DYNA feature has been studied in side impact airbag applications, and it is being further investigated in passenger side airbag applications to gain confidence in its application.

• Evaluation of LS-DYNA® Corpuscular Particle Method for Side Impact Airbag Deployment Applications

  Chin-Hsu Lin, Yi-Pen Cheng (General Motors), Jason Wang (LSTC)

  A uniform pressure method, i.e. no pressure variation on bag surface and location, in LS-DYNA has been commonly used to simulate airbag deployment and interaction of airbag with the occupants. Another newly developed LS-DYNA CPM (Corpuscular Particle Methodology) has gained recognition and acceptance recently because it considers the effect of transient gas dynamics and thermodynamics by using a particle to represent a set of air or gas molecules and then a set of particles to represent the entire air or gas molecule in the space of interest. This innovative method, however, has yet be fully utilized and applied with confidence in airbag deployments simulation without systematic tests and validations to avoid non-physical tuning factors traditionally being applied to the uniform pressure airbag finite element models. In this paper, inflator closed and vented tank tests, static airbag deployment test, and linear impactor tests with various configurations and impact speeds are systemically conducted and then correlated with a CPM airbag model to determine whether the methodology can be applied for all the tests and whether any tuning factors should be applied in the process. This innovative LS-DYNA particle method has been fully investigated in this systematic study by correlating it with a comprehensive set of inflator tank tests, static airbag deployment, and rigid linear impactor tests. The correlations start from inflator closed and vented tank tests to verify the provided inflator characteristics, mass flow rate and temperature curves. The inflator characteristics will then be employed into static airbag deployment simulation to determine the airbag fabric heat convection coefficient, which is adjusted in this simulation to match the test pressure profile. This is the only parameter tuned to match the test pressure. This airbag model is then used to simulate those linear impact tests. With the systematic validations and correlations to avoid using tuning factors, the airbag model results in a good match of the overall airbag internal pressure and impactor deceleration histories with the tests and the simulations for all the linear impactor tests conducted. Effects of the inflator variations are also studied to illustrate the potential bounds of deceleration and airbag chamber pressure in impacts.

• Evaluation of Performance, Reliability, and Consistency of MPP Version of LS-DYNA

  Cing-Dao Kan - The George Washington University, Yih-Yih Lin - Hewlett-Packard Company

  This paper reports the on-going evaluation of the current distributed memory (MPP) versions of LS-DYNA by using set of large size vehicle finite element models with number of elements ranging from 200,000 to 380,000. The evaluation focuses on the scaling performance, reliability, and consistency of the MPP code.

• Evaluation of rail height effects on the safety performance of W-Beam barriers

  Dhafer Marzougui, Pradeep Mohan, Cing-Dao (Steve) Kan - The George Washington University, USA, Kenneth Opiela - US Department of Transportation, USA

  The objective of this study is to investigate the effect of rail height on the safety performance of G4(1S) w-beam guardrail systems. The study involved three steps. In the first step, a detailed finite element model of the G4(1S) guardrail system was created. The model incorporated the details of the rail, connections, the post, the blockout, and the soil in which the post was embedded. To validate the model of the wbeam guardrail system, a model of the setup of this w-beam system in previous fullscale crash tests was created. Simulations were performed using this model and the results were compared to the full-scale crash test data. The results were similar indicating that the model was an accurate representation of the actual system. In the second step of the study, the validated model served as the basis for four additional models of the G4(1S) guardrail to reflect varying rail heights. In two of the four models, the rails were raised 40 and 75 mm (1.5 and 3 inches). In the other two models, the rails were lowered 40 and 75 mm. Simulations with these four new models were carried out and compared to the first simulation to evaluate the effect of rail height on safety performance. The simulation results indicated that the effectiveness of the barrier to redirect a vehicle is compromised when the rail height is lower than recommended. The third step of the study consisted of performing full-scale crash tests with the guardrail at standard height and 60 mm (2.5 inches) lower. The data from the crash tests validated the simulation results.

• Evaluation of Simulation Results using Augmented Reality

  M. Lechner, R. Schulte, M. Merlein (University of Erlangen-Nürnberg)

  Simulation has become an important tool in order to design forming processes in a time and cost efficient way. However, simulation results are almost exclusively visualized using conventional laptops or personal computers. Especially, in the press shop an analysis directly at real parts is not possible at the moment. At the same time, there has been a very convincing development in the field of Augmented Reality hardware in recent years. In particular, the iPhone and the iPad of the company Apple as well as the HoloLens of the company Microsoft offer interesting solutions for the industry. Thereby, the Augmented Reality applications are until now limited to CAD-data or assembly problems. Therefore, within scientific contribution a method to visualize simulation results from LsDyna in a simple way is presented. It will be explained, how new simulation results can be loaded on runtime and which use cases can be derived with the technology. In the end, Augmented Reality solutions with HoloLens as well as iPhone/iPad will be compared and evaluated.

• Evaluation of the Dropping of a Propeller Shaft During Installation on the USS COLE a DDG 51 Class Destroyer

  Phillip Burnside - United States Naval Reserve

  A terrorist bomb damaged the USS COLE by putting a hole in the side of the ship that was over 30 feet in diameter and flooded the forward engine room. After the ship was stabilized it was placed on the heavy lift ship, the BLUE MARLIN. The BLUE MARLIN brought the USS COLE back to Ingalls shipyard in Pascagoula, Mississippi for repair as seen in figure 1. The Navy wanted to expedite the repairs to the USS COLE and so parts from the battle damage spare inventory were used to obtain components that needed to be replaced to significantly reduce the lead-time needed. During the repair it was determined the shafts needed replacement. To do this each section of the shaft is slowly slid into the hull of the ship using rigging to swing it through the openings in the bulkheads. It was during one of these rigging moves that a section of the shaft was being temporarily suspended by rigging during installation into the ship just short of a bulkhead shaft clearance opening. While in this configuration the rigging at the inboard end of the shaft failed. This dropped the shaft about 12 inches onto a temporary channel that was welded to the bulkhead to support the shaft while it is passed through the bulkhead opening.

• Evaluation of the Impact Condition for a High Capacity Spent Nuclear Fuel System

  Mike Yaksh, S. Alan Lin - NAC International Inc.

  Evaluations are performed for the structural component of a fuel basket in a sealed container which is used for maintaining the configuration of spent nuclear fuel during storage. Spent fuel assemblies are placed into a basket structure which is comprised of separate tubes whose positions are maintained by a series of pins and sockets and an exterior frame work of stiffeners. The canister is placed in a vertical storage cask. The controlling condition is associated with lateral impact of the tip over of the storage cask which results in deceleration being applied normal to the axis of the basket and spent fuel. It is necessary to investigate the potential geometric instability of the array of tubes as well as the potential for a pin-socket component to fail in shear. The angular orientation of the basket affects the development of potential instabilities as well as the level of shear developed in the basket tubes at the pin- socket. In this paper the impact analyses for a system to store 87 BWR fuel assemblies are presented.

• Evaluation of the Injury Risks of Truck Occupants Involved in a Crash as a Result of Errant Truck Platoons

  Hanxiang Jin, Yunzhu Meng, Alexandrina Untaroiu, Costin Untaroiu, Virginia Tech, Blacksburg, VA;, Roshan Sharma, Chiara Silvestri Dobrovolny, Texas A&M Transportation Institute, College Station, TX

  Platooning is an extension of Cooperative Adaptive Cruise Control (CACC) that realizes automated lateral and longitudinal vehicle control while moving in tight formation with short following distances. The truck platoons are expected to include at least five trucks with drivers in the first and the last trucks. This paper discusses the methodology and presents results of a single tractor-van trailer impact into a concrete barrier, which is a dedicated approach for a broader truck platooning implication research funded and supported by Safety through Disruption (Safe-D) University Transportation Center (UTC).

• Evaluation of Various Numerical Methods in LS-DYNA ® for 3D Crack Propagation

  Ala Tabiei, Wenlong Zhang (University of Cincinnati)

  In this paper, four different numerical methods implemented in the large scale simulation code LS-DYNA ® are evaluated to determine their abilities and limitations in fracture problems especially 3-d crack propagation problems. These methods are: Finite Element Method (FEM), Discrete Element Method (DEM), Element Free Galerkin (EFG) method and Extended Finite Element Method (XFEM). Their methodologies are briefly described and several numerical simulations are carried out and compared with experiment results. In some examples, fracture parameters are evaluated and mesh sensitivity is studied. Their potentials and limitations are discussed.

• Evaluation of Viscoelastic Material Models in LS-DYNA based on Stress Relaxation Data

  Gokula Krishnan M, Vesna Savic, Bryan Cordeiro, Surjayan Biswas

  Viscoelastic behaviour of a material is often used as a probe in the field of material science since it is sensitive to the material’s chemistry and microstructure. The behaviour enables understanding of the quantity of energy absorbed by the material’s internal structure and the energy dissipated to the surroundings. The viscoelastic properties can be determined experimentally by tests such as stress relaxation, creep, or Dynamic Mechanical Analysis (DMA).

• Event Detection Methods for Multi-Sensor CAE-Data

  R. Iza-Teran, D. Steffes-lai, Anh-Duy Pham, M. Pathare, J. Garcke

  Virtual product development especially in car development requires the evaluation of multiple sensors signals in the simulations as one of the tasks; the sensor data is also needed for comparison with the real product. Comparing many virtual sensors manually from many simulations turns out to be a time consuming and challenging task. We propose a methodology and workflow setting that address this challenge, allowing a similarity comparison of hundreds of sensors from hundreds of simulations detecting similar events (clusters) or very different behavior as outliers. The approach uses a method of dimensionality reduction combined with different type of clustering methods including hierarchical clustering. The dimensionality reduction reduces the virtual sensor data information such that a visual comparison of thousand sensor signals can easily be performed in 3D, the hierarchical clustering on the other hand allows a localized comparison of sensor signals. The approach is demonstrated using binout Ls-Dyna data from a frontal crash example with many model variants containing many sensor data per simulation as well as for head impact computation.

• EVOLVING TECHNOLOGY: MULTI-PHASE, MULTIMATERIAL, ALE APPROACH AND TOOL DEVELOPMENT FOR BURIED BLAST SIMULATION

  Dr. Rahul Gupta - U.S. Army Research Laboratory Aberdeen Proving Ground

  Modeling the response of structures subjected to blast from shallow buried explosives poses a challenge, primarily due to the inherent coupled interaction. The response of the structure affects the surrounding blast pressure field, which in turn, affects the loading on the structure; therefore the problem is coupled in nature. The problem is complicated due to the difference in time scales associated with the blast loading and structural damage. Damage mechanisms such as structural collapse generally occur later compared to the duration of the blast since the duration of the failure event is much longer. In this presentation, an evolving methodology, combining the effects of early coupled interaction and later structural damage, Fluid-Structure Interaction (FSI) effect using multi-material and multi-phase Arbitrary Lagrangian Eulerian (ALE) formulation is described. The utility of the methodology is demonstrated through a newly developed toolset for LS-DYNA ALE based simulation and an example involving blast loading on a highfidelity plate structure supported through Vertical Impulse Measurement Fixture [VIMF]. Data from the experiment is compared with the LS-DYNA ALE simulation to investigate the efficacy of the methodology. Results reveal that this new analysis tool yields accurate results that will be useful in predicting vehicle response and provide a means of quickly iterating on proposed structural solutions.

• Examples' manual for *USER_LOADING option

  Melissa Adoum, Vincent Lapoujade - CRIL Technology Correspondence

  The aim of this study is to understand how the *USER_LOADING option works and to give some examples of its use. This option uses the subroutine loadud, its usage will be described step by step and it is illustrated with four examples : • Plate loaded with time dependant pressure, • Plate loaded with displacement dependant pressure, • Randers-Pehrson & Bannister Tests, • Plate loaded by an explosion of 5kg of TNT. Some of those examples use loadings that can be also applied through LS-DYNA existing options, thus the results obtained with the user loading option could be compared and validated.

• Experience a complete virtual crash and safety laboratory with the aid of the ANSA pre-processor

  E. Dagdilelis, T. Fokylidis, T. Lioras (BETA CAE Systems)

  With safety protocols and regulations becoming increasingly enhanced, safety analysts try to keep up replicating all possible crash event scenarios in laboratories using specifications that frequently change. In this pursuit, it is crucial for analysts to have at their disposal accurate and robust digital models that enable the tune and study of any real crash event parameter. Through the ANSA pre-processor, BETA CAE Systems offers an extensive crash and safety portfolio of automated tools for simulation modelling, to create a complete “virtual crash and safety laboratory”. Such tools include this of the seat and the dummy guide, from the identification of HPOINT of the seat to the positioning of the coupled restrained seat-dummy system according to a regulation or a test data position, available not only for standard crash dummies but also for human body models. Pedestrian and Interior tools ensure the proper marking of the exterior and interior of the vehicle but also the accurate positioning of the headform to the desired targets. The Impactor tool enables the positioning of barriers/impactors according to all available regulations. Moreover, the Knee Mapping plugin helps the analyst avoid knee modifier, while Airbag stitching and folding tools set up the pre-crash simulations required for the proper treatment of the airbags. The current paper presents all the afore mentioned tools and more handy features that crash and safety analysts need to set up detailed and accurate models for different regulations fast, and with the minimum human interaction.

• Experience from Using a New Material Model for Stainless Steels with TRIP-effect

  Daniel Hilding - Engineering Research Nordic AB, Erik Schedin - Outokumpu Stainless AB, Avesta Research Centre

  This paper presents experience from using a recently developed material model for austenitic stainless steels with TRIP-effect for simulation of sheet metal forming. Results from two different forming operations are presented. In materials with TRIP-effect, a phase transformation from austenite to martensite occurs during forming that significantly affects the hardening behavior. The effect is sensitive to the amount of straining as well as the temperature. For materials that have a strong TRIP-effect new forming techniques are possible that can lead to very light and strong components. The material model for austenitic stainless steel sheet exhibiting the TRIP-effect has been implemented in LS-DYNA.

• Experience from using recently implemented enhancements for Material 36 in LS-DYNA 971 performing a virtual tensile test

  Michael Fleischer - BMW Group, Thomas Borrvall - Engineering Research Nordic AB, Kai-Uwe Bletzinger - Technische Universität München

  In today’s automotive industry the development of car bodies considerably depends on the use of computer-aided tools to meet the challenges of rising product complexity and growing number of variants. Today, enabled by modern simulation software, improved material models and numerical methods, simulation has become essential for the evaluation of sheet-metalstamping processes before press tools are manufactured. Though modern material models are available, some effects are not described correctly, because some parameters are assumed to be constant. In reality, a lot of these “constant” values must be considered variable. To better represent the real material behaviour, some enhancements for the standard material models have to be implemented to get a more realistic simulation. In this paper we present the results of virtual tensile tests, comparing input- and outputparameters, using the first LS-DYNA material model with variable Lankford coefficients / R-values, yield curves, volume and Young’s modulus. All these features are now available in one material model – LS-DYNA 971 Material 36.

• EXPERIENCE WITH CRASH SIMULATIONS USING AN IGA BODY IN WHITE

  Frank Bauer, Tian Yugeng, Lukas Leidinger, Stefan Hartmann

  With the IGA (Isogeometric Analysis) technological approach [1], the transfer processes from CAD to CAE can be simplified in the future and false predictions due to discretization effects can be reduced. In recent years, IGA and the corresponding toolset has increasingly developed into a setup that comes close to industrial use [2]. In order to test the use of IGA in industrial environments, a body in white (BIW) that was previously modelled with a „classic“ FE approach was also modelled with IGA and installed in a so-called hybrid model in a full vehicle crash simulation. For this purpose, the CAD data used as the basis for the FE model creation was used to directly create IGA surfaces. The aim of implementing a body in white using IGA was, on the one hand, to look at the processes in terms of usability, automation capability and implementation quality; and, on the other hand, to understand how hybrid crash simulations behave in terms of computing time and stability. In order to see different design effects in crash simulations, a front crash and a side crash were carried out and compared with existing FE models. The investigations show the entire process, from geometry conversion to full vehicle simulation and explain the findings in comparison with the FE model.

• Experience with Material and Fracture Modeling at FCA US LLC
• Experiences with LS-DYNA Implicit MPP

  Cleve Ashcraft, Roger Grimes, Bradley Maker - Livermore Software Technology Corporation

• Experimental and Numerical Investigation of Fracture in Aluminium

  P. Du Bois - Consultant, Prof. S. Kan, M. Buyuk - George Washington University, J. He - Engineering Technology Associates

  To assess the problem of containment after a blade-off accident in an aero-engine by numerical simulation the FAA has instigated a research effort concerning failure prediction in a number of relevant materials. Aluminium kicked off the program which involved an intensive testing program providing failure data under different states of stress, different strain rates and different temperatures. In particular split Hopkinson bars were used to perform dynamic punch tests on plates of different thicknesses allowing to investigate the transition between different failure modes such as petaling and plugging. Ballistic impact tests were performed at NASA GRC for the purpose of validation. This paper focuses on the numerical simulation effort and a comparison with experimental data is done. The simulations were performed with LS-DYNA and a tabulated version of the Johnson-Cook material law was developed in order to increase the generality, flexibility and user-friendliness of the material model.

• Experimental and Numerical Investigation of Fracture in Aluminium

  P. Du Bois - Consultant, Prof. S. Kan, M. Buyuk - George Washington University, J. He - Engineering Technology Associates

  To assess the problem of containment after a blade-off accident in an aero-engine by numerical simulation the FAA has instigated a research effort concerning failure prediction in a number of relevant materials. Aluminium kicked off the program which involved an intensive testing program providing failure data under different states of stress, different strain rates and different temperatures. In particular split Hopkinson bars were used to perform dynamic punch tests on plates of different thicknesses allowing to investigate the transition between different failure modes such as petaling and plugging. Ballistic impact tests were performed at NASA GRC for the purpose of validation. This paper focuses on the numerical simulation effort and a comparison with experimental data is done. The simulations were performed with LS-DYNA and a tabulated version of the Johnson-Cook material law was developed in order to increase the generality, flexibility and user-friendliness of the material model.

• Experimental and Numerical Investigation of the Tearing Resistance of a Parachute Woven Fabric using LS-Dyna ®

  B.Perin, R.Blois, P.Bordenave (DGA Aeronautical Systems), Ch.Espinosa (Université de Toulouse)

  The performance of a parachute system is conditioned by its ability to sustain the loads applied by its environment during its life. Among others tear resistance is crucial since the unstable propagation of small defects into cracks can lead to the catastrophic loss of load carrying capacity. Defects under consideration are pre-existing notches or cuts. Experimental campaigns of quasi-static tear resistance in the warp and weft directions of parachute woven flexible fabrics have been realized at DGA Aeronautical Systems following the normalized tests defined by NF G07- 145 and NF G 07-149 (‘trousers’ tear or Single Rip Method, and ‘nail’ tear, see Fig. 1). On the contrary to the case of a metallic material, which tear resistance can be related to notch resistance through the yield strength and local plasticity, tear resistance of a tissue involves complex stress and stain distributions in the yarns of the woven fabric. It is shown that sliding of the rip stop yarns are not well handled by the testing standards. A numerical simulation plan has been designed and operated in order to determine the characteristics of a representative numerical model for both the material behavior and the large flexible structure, in the perspective of including it in a full 3D FSI simulation. Results are presented and compared to experimental ones. Using a homogenized anisotropic material, the size of the mesh and the contact algorithm are the critical parameters that handle the crack propagation through the local wrinkles and stresses description. Even though the out of plane deformations are not completely well reproduced for the Single Rip Method, the final numerical model is quite satisfactory regarding the force- displacement curve prediction for both test standards. Perspectives are driven for both enhancing the testing standards and deriving a more representative model for future 3D FSI models.

• Experimental and Numerical Study of Submillimeter-Sized Hypervelocity Impacts on Honeycomb Sandwich Structures

  F. Plassard (Thiot-Ingenierie), H. Abdul-hamid, P Deconinck, P-L Héreil, J. Mes-poulet (Thiot-Ingenierie), C. Puillet (CNES)

  This paper deals with hypervelocity impacts of submillimer-sized debris on honeycomb sandwich panels. These debris, which are mostly present within the low Earth orbit, indeed represent a real threat for spacecrafts and satellites. In fact, for debris large enough to be tracked, pre-determined debris avoidance manoeuvre is usually conducted to prevent any damage. Submillimer-sized debris, however, are too small to be identified and therefore spatial structures must be protected against such threat. Honeycomb structural panels and whipple shields have been used as primary shielding against orbital debris impact. The protection capability is usually estimated using Ballistic Limit Equations (BLE). These data have been built from experimental tests on whipple shield protection and transposed to honeycomb sandwich panels. In the case of Whipple shield, the debris cloud generated at the impact on the bumper sheet expands until reaching the rear wall. BLE for Whipple shields only depends on materials properties, protection geometry, angle of incidence and impact velocity. For honeycomb sandwich panels, the debris cloud is partially channelled within honeycomb cells, thus limiting its radial expansion. The channelling effect is thus a function of the honeycomb cell geometry. The honeycomb BLE presented by the Centre d’Etudes de Gramat (CEG) in 2008 has been introduced in order to take into consideration such effect.

• EXPERIMENTAL AND NUMERICAL COMPRESSIVE TESTING OF ALUMINUM FOAM FILLED MILD STEEL TUBULAR HAT SECTIONS

  William Altenhof, Rita Turchi - University of Windsor, Anne-Marie Harte - Cymat Corp

  This research deals with the experimental and numerical testing of aluminum foam filled mild steel tubular hat sections under axial compression conditions. The presence of aluminum foam within the tubular hat section provides a means of stabilizing the buckling process of the tube under axial compression. This method of applying internal support allows for a greater number of folds to be observed in the axial crushing of the hat sections and hence an increase in the energy absorption of the tube filled with aluminum foam, compared to a regular hat section without the presence of metallic foam. Experimental testing was conducted on mild steel tubular hat sections with and without the presences of aluminum foam within the tube. Load/displacement curves were developed from the experimental tests and integrated to determine the energy absorption capabilities of the tubular hat sections and the influence of the metallic foam. Finite element simulations, using LS-DYNA, were conducted on numerical models of the experimental testing procedure. An acceptable engineering correlation between the experimental and numerical testing methods was observed. This paper will present and compare the experimental and numerical observations from the compressive tests and also provide information on the energy absorption capacity of the tubular hat sections.

• Experimental and Numerical Testing of the V50 Impact Response of Flexible Fabrics: Addressing the Effects of Fabric Boundary Slippage

  Gaurav Nilakantan, Michael Keefe, John W. Gillespie Jr. - University of Delaware, Eric D. Wetzel, Richard Merrill, Travis A. Bogetti, Rob Adkinson - US Army Research Laboratory

  The impact testing of woven fabrics comprised of high strength and high modulus yarns is probabilistic in nature. This paper presents results from the experimental impact testing of 50.8 mm×50.8 mm scoured Kevlar S706 fabric samples held on four sides and impacted at the center by a 0.22 caliber ball bearing projectile. The V50 velocity response is obtained by performing impact experiments over a range of velocities and fitting the data to a normal distribution function. The impacted fabric samples show varying extents of slippage from underneath the fixtures. The effect of clamping pressure on the extent of fabric slippage is studied by varying the torque on the four bolts used to hold the fixtures together. Results from the experimental testing are compared against numerical predictions which did not consider fabric slippage effects. A simple new method to numerically model fabric slippage is developed and implemented into our computational probabilistic framework. Simulations are run using a Langlie method to obtain the new V50 velocity response of a Kevlar S706 fabric with spool based strength mappings and with boundary slippage present. Comparisons are then made between the experimental and numerical results.

• Experimental and Simulation Characterization of the Suspension of a Small Car

  W. Tiu - University Hertfordshire

  This paper will describe the work carried out to compare the experimental response of the car using a four actuator vibration rig and that obtained from an LS-dyna analysis using the same loading spectrum as that used in the physical experiment. The public domain frontal crash FE model was modified to reduce the solution time. Most of the materials used in the panels were changed to rigid as these were not expected to deform during a vibration analysis. The spring and damper rates in the FE model were modified in an iterative process until convergence was achieved. Road load data was then obtained by driving along a prescribed circuit with relevant instrumentation. The terrain of the circuit was then laser scanned to obtain a digital model. The digital terrain was then used in the simulation of the correlated car model going around the same circuit. The experimental/simulation responses were then compared against one another. The availability of the same physical and FE model has enabled our M.Sc. Engineering students to obtain a better understanding of suspension analysis and correlation process. Furthermore the exposure to both testing and simulation techniques will equip them better to face future challenges.

• Experimental and Simulation Characterization of the Suspension of a Small Car

  W. Tiu - University Hertfordshire

  This paper will describe the work carried out to compare the experimental response of the car using a four actuator vibration rig and that obtained from an LS-dyna analysis using the same loading spectrum as that used in the physical experiment. The public domain frontal crash FE model was modified to reduce the solution time. Most of the materials used in the panels were changed to rigid as these were not expected to deform during a vibration analysis. The spring and damper rates in the FE model were modified in an iterative process until convergence was achieved. Road load data was then obtained by driving along a prescribed circuit with relevant instrumentation. The terrain of the circuit was then laser scanned to obtain a digital model. The digital terrain was then used in the simulation of the correlated car model going around the same circuit. The experimental/simulation responses were then compared against one another. The availability of the same physical and FE model has enabled our M.Sc. Engineering students to obtain a better understanding of suspension analysis and correlation process. Furthermore the exposure to both testing and simulation techniques will equip them better to face future challenges.

• Experimental Design for Negative Triaxialities: Ductile Fracture Under Combined Uniaxial Tension and Hydrostatic Pressure

  Robert L. Lowe, Luke D. Hoover, Christopher A. Negri (University of Dayton)

  Many modern continuum-scale approaches for modeling the ductile fracture of metals regard the equivalent plastic strain at fracture as a function of the stress triaxiality and Lode parameter, a pair of invariant-based quantities that together characterize the three-dimensional state of stress at a point. Generally, these ductile fracture models (whether parameterized or tabulated) are calibrated using standard mechanical tests, e.g., notched axisymmetric (round), plane stress (thin), and plane strain (thick) specimens subjected to tensile loading. However, these standard tests are only able to capture a limited window of stress states, leaving potentially important “regions” of the ductile fracture model unpopulated with experimental data. For instance, although previous research has suggested that fracture will not occur below a triaxiality of 0.33 (the “cut-off” value), recent ballistic impact simulations involving 0.5-inch-thick titanium Ti-6Al-4V target plates predicted large negative (compressive) triaxialities in the vicinity of the adiabatic shear band. These results not only suggest the potentially unanticipated importance of the negative triaxiality (compressive) region of Lode-triaxiality stress space, but also the need to experimentally revisit previous interpretations of the “cut-off” value of the triaxiality. As a first step, this paper presents a novel physical interpretation of the Lode parameter = 1 (constant) meridian over a range of triaxialities, spanning positive (tensile) to negative (compressive). Guided by this physical insight, ductile fracture experiments that employ hydrostatic pressure superposed on uniaxial tension are proposed and numerically simulated in LS-DYNA®, with initial efforts focusing on 2024-T351 aluminum. Our numerical simulations provide a promising “virtual” proof-of-concept demonstrating that stress triaxiality can be tuned (at constant Lode parameter) by adjusting the magnitude of the applied pressure, allowing a wide range of stress states to be accessed through a single experimental test setup.

• Experimental Investigation and Numerical Characterization of the Bake-Hardening Effect of a Two-Phase Steel

  D. Koch, A. Haufe (DYNAmore); M. Feucht (Daimler)

  Typically, the material characterization for the simulation is performed based on the virgin material, which is used for the preparation of the corresponding component. However, due to the processing of the material, its properties may vary greatly. Exemplarily, in Fig. 1, experimental results are shown based on the same material. The test specimens belonging to the red curve were pre-stretched and heated prior to the experiment, while the test specimens belonging to the black curve were not treated at all. Obviously, a material card adapted to the untreated material would not provide an acceptable match with the material being treated. Therefore, a closer look at the influence of pretreatment as well as the development of methods to take this influence into consideration is of great interest.

• Experimental Investigation and FE Analysis of Fiber Woven Layered Composites under Dynamic Loading

  P. A. Mossakovsky, F. K. Antonov (Reaserch Institute of Mechanics of Lomonosov Moscow State University), M. E. Kolotnikov, L. A. Kostyreva (FSUE), A. M. Bragov, V. V. Balandin (Reaserch Institute of Mechanics of Lobachevsky State University of Nizhni Novgorod)

  Woven composites are used in a wide range of industrial applications such as development of individual body armor, aviation, astronautics and others . Thus, it is important to learn the mechanical behavior of the composite and to perform it’s adequate modeling under dynamic impact loading. The paper is concerned with modeling of woven fabric composite made of aramid yarns. The experimental investigation including static tests, dynamic tests with the Split Hopkinson Bar and ballistic impact tests was performed. The full-scale model with yarn-level detalization was constructed using obtained experimental data. The method allows getting qualitative results on the small specimens but realistic analysis of real-size models consisted of billion elements requires huge computational resources. So the paper is focused on the development of the alternative homogenized macro-model of the layered composite.

• Experimental Investigation on the Damage Behaviour of a Rubben-Toughend Polymer

  M. Helbig (DYNAmore)

  Rubber-toughened polymers such as ABS are composed of a thermoplastic matrix and small rubber particles e.g. [1]. Macroscopic effects of the rubber particles are a reduced overall stiffness and yield strength and an enhanced ductility and fracture toughness [2,3]. These macroscopic effects are caused by mechanisms on the micro scale such as shear yielding, void growth and crazing [4]. In the present work experimental investigations on an ABS-material are used to characterize the deformation behavior. The damage and fracture behavior is characterized by cyclic tests. An increasing volume strain indicates the crazing mechanism, which goes along with an anisotropic yielding behavior. Tensile tests with an inelastic pre-deformed ABS-material show the evaluation of the anisotropic yielding behavior.

• Experimental Investigation and FE Modeling of the High Temperature Dynamic Properties of Metals in the Kolsky method

  Pavel A. Mossakovsky, Alexander V. Inyuhin, Fedor K. Antonov (Reaserch Institute of Mechanics of Lomonosov Moscow State University, Russia), Liliya A. Kostyreva (FSUE "GTERPC 'Salut", Russia)

  In a wide range of practical problem on the dynamic strength associated with the impact and penetration an adequate definition of the material properties as a strain rate and temperature function has a great importance. One of the most effective and reliable methods for determining materials properties at high strain rates is the Kolsky method using the split Hopkinson bar [1]. This method is based on the one-dimensional theory of elastic wave propagation and the assumption of homogeneity of strain in the sample. It allows to obtain the deformation diagram for the processes of compression and tension in the range of strain rates 200-10000 s-1. Two basic schemes of the initial heating of the sample exist to study the materials properties at elevated temperature. In the one case, the heater is located directly on the axis of the rods (Fig.1) and heat-exposed not only the sample but also the adjacent parts of the rods. In the second scheme, the furnace is at the distance from the rod (Fig. 2), heat is directly exposed to the sample. Thus, researcher should take into account a non-uniform temperature field produced by rapid cooling of the sample while delivering from the oven to the bars. In all cases it is necessary to clarify the standard scheme of the Kolsky method. The paper is concerned with a numerical and experimental investigation of the temperature and the stress-strain state in the specimen in compression tests with split Hopkinson bar with a remote oven. The goal was to determine the degree of heterogeneity of the temperature field in the sample during the test and to discuss the approaches to the refinement of a standard methodology.

• Experimental Procedure and Hardening Model for Simulation Considering Forming and Baking Effects

  JiHo Lim, Haea Lee, Jisik Choi

  The automotive body is manufactured by assembling parts made by forming, and then going through a painting process. Sheet metal parts formed by press have the plastic strain, and bake hardening that material strength increases according to the plastic strain during the baking process of painting, occurs. Therefore, the actual assembled automotive parts are stronger than the original materials due to the combined effects of work hardening and bake hardening. Automobile crash analysis generally applies the properties of the original material, but the change of material properties in real parts acts as a factor of error in crash analysis. Especially, these characteristic is more pronounced in giga-steel. Considering the increasing trend of giga-steel for weight reduction, it is necessary to consider the change of material properties due to work hardening and bake hardening in crash analysis.

• Experimental Validation of Detecting Surface Deflections on Sheet Metal Parts with LS-DYNA

  A. Weinschenk, A. Schrepfer, W. Volk (TU München)

  The appearance of surface deflections on sheet metal parts is undesirable. When surface deflections are detected on a sheet metal part during tryout, the tool geometry has to be modified. This procedure is performed at a later stage of the product development process which leads to high costs and effort. Therefore, it is useful to detect surface deflections before the actual production in the finite element simulation. Then, it is much easier to modify the tool geometry in such a way that surface deflections don’t occur any more. In this paper, the reliability of the stoning method provided by LS-Dyna is investigated in a parameter study. The influence of the moving direction, the step size, the chosen area of the part for the stoning, the stone length, and the stone width on the detected surface deflections are analyzed. The results show that the chosen size of the area for the detection has a huge effect on the detected surface deflection. Similarly, the stone length has an influence but the stone width does not. To validate the finite element simulation, the strain distribution of the numerical part is compared to the physical part. The stoning method is applied to a physical part and the detected surface deflections are compared to those detected in the simulation. The study is conducted on a typically challenging part: a curved sheet metal part with a door handle depression.

• Experimental-numerical determination of the Taylor- Quinney coefficient

  J. Johnsen (Enodo), L. Dæhli, T. Børvik, O. Sture Hopperstad (NTNU)

  During plastic deformation of a metal, a part of the plastic work is stored in the material due to local distortion of the crystal lattice, while the remainder is dissipated as heat. The part of the plastic work dissipated as heat can be observed on a macroscopic scale through thermal measurements in high strain rate experiments. Typically, this fraction of plastic work converted into heat is assumed to be constant and around 90%. In this study, we have performed tension tests at a constant crosshead velocity of 0.6 mm/s on flat notched specimens from a DP600 steel material. Digital image correlation (DIC) was used to apply virtual extensometers spanning the length of the notched area. Furthermore, an infrared camera was used to measure the temperature increase over the same area as monitored by DIC, enabling correlation between temperature and displacement. These temperature-displacement curves were used as the target curves in thermomechanical simulations to obtain the Taylor-Quinney coefficient as a function of the equivalent plastic strain. It was found that the Taylor-Quinney coefficient exhibits quite large variations during the experiment, ranging from a minimum of about 0.5 in the beginning of the test, to about 0.95 at the end of test.

• Experiments and Simulations of Explosives: Shock Wave Propagation around a Convex Structure

  N. Van Dorsselaer, S. Eveillard, S. Trélat, Institut de Radioprotection et de Sûreté Nucléaire (IRSN) 31, Avenue de la Division Leclerc, 92260 Fontenay-aux-Roses, France

  IRSN provides technical support to the relevant French authorities involved in the security of nuclear material, nuclear facilities and in the transportation of nuclear material. In order to improve its knowledge on blast wave propagation, IRSN has set-up a laboratory scale able to perform detonations of solid explosives against rigid structures (no damage or deformation). In July, 2017, the 7th experimental campaign was conducted on this set-up to study the shock wave propagation around a convex structure. Several configurations were tested, involving a charge of 50 g of TNT equivalent and a horizontal half cylinder. The pressure data obtained have been compared with simulations performed using LS-DYNA® and OURANOS (French software developed by CEA). Concerning simulations, a process of validation was conducted on both software programs, in order to test mesh choices (mesh size, structured or unstructured mesh…) and boundary conditions (mesh boundaries, coupling…).

• Expert Rules as a Powerful Support of the Topology Optimization Procedures of Crash Structures

  Prof. A. Schumacher (University of Wuppertal)

  Topology optimization for the layout finding of structures is commonly used for linear static mechanical problems within the industry. The most often used approach is the subdividing of the topology domain in small parts (pixel or voxel) and to distinguish whether there is material or not [1]. E.g. the well-known homogenization method minimizes the mean compliance considering a mass constraint. These methods work very fast, because they use existing analytical sensitivities of the most relevant objectives like mean compliance, stresses or mass.

• Expert Rules as a Powerful Support of the Topology Optimization Procedures of Crash Structures

  Prof. A. Schumacher (University of Wuppertal)

  Topology optimization for the layout finding of structures is commonly used for linear static mechanical problems within the industry. The most often used approach is the subdividing of the topology domain in small parts (pixel or voxel) and to distinguish whether there is material or not [1]. E.g. the well-known homogenization method minimizes the mean compliance considering a mass constraint. These methods work very fast, because they use existing analytical sensitivities of the most relevant objectives like mean compliance, stresses or mass.

• Explicit and Implicit FE Simulations of Material Tests for Subsequent Durability Analyses

  P. Thumann, M. Wagner (OTH Regensburg); B. Suck (BMW); S. Marburg (TU München)

  To improve the efficiency in sheet metal manufacturing, more and more press systems with increased stroke rates are in use. Due to the increased stroke rates, the structural-dynamic loads too increase. Thereby, not only the press systems are highly loaded, but also the tools for manufacturing the blanks. This has to be accounted for in the early design phase of the tools in the virtual process chain. Because of safety requirements, high safety factors are used during the design of the tools, leading to high manufacturing costs. Furthermore, stroke rates are limited due to the movement of high masses of the tools, reducing the productivity of the press system. To reach smaller allowable safety factors, resulting eventually in fewer costs, and to improve the stroke-limitation due to the moved masses, a simulation methodology for the evaluation of the durability of selected tool components is developed. Therefore, special material tests were designed and carried out. The tests have to be investigated with FE simulations for subsequent durability analyses.

• Explicit and Implicit Simulations for Die-Less-Hydroforming- Structures including Welding, Forming and Load Capacity using LS-DYNA® and DynaWeld®

  Andreas Metzger, Thomas Ummenhofer, Karlsruhe Institute of Technology, KIT Steel & Lightweight Structures

  Within the scope of Die-Less-Hydroforming, two or more flat metal blanks that have the same cutting-geometry are stacked congruently one above the other, and are then seal-welded on their common edges. Afterwards, the resulting seal-welded double- or multi-layered blank is inflated by a medium (e.g. water) whereby it transforms to a spatial structure under continuous internal pressure increase. Since no external forming tool is used, and because of the thin blank sheets (ranging from 0.5 up to 4mm), Die-Less-Hydroforming is very sensitive to buckling phenomena. Although this unconventional forming technology (also known under some synonyms, e.g. inflating metals) was first mentioned in the academic discourse in the 1920s [1], it is currently very up-to-date among many users, and versatile applications in different fields are developing.

• Explicit Isogeometric B-Rep Analysis on Trimmed NURBS-Based Multi-Patch CAD Models in LS-DYNA

  L. Leidinger (BMW)

  A volatile and highly competitive market forces automotive Original Equipment Manufacturers (OEMs) to speed up their vehicle development processes. A key component in this process is structural design through Computer Aided Design (CAD) and Finite Element Analysis (FEA). Although the efficiency of this process has been significantly improved over the past years, the necessary conversion of NURBS-based CAD models into (linear) polynomial-based FEA models turned out to be a persistent challenge. Generating FEA models usually involves time- and labor-intensive clean-up, de-featuring and meshing steps leading to vehicle model generation times of several weeks. During the iterative vehicle development process, such model generations are even performed multiple times. It is furthermore current practice to apply design changes motivated by structural analysis results directly on the FEA model, which then diverges more and more from the initial CAD model. Adapting the CAD model to the modified FEA model for the next design cycle again requires a significant amount of manual work.

• Exploring Ansys LS-DYNA's Battery Modeling Capabilities

  Iñaki Çaldichoury, Kevin Kong, Pierre L’Eplattenier, Vidyu Challa

  Over the past decade, considerable advances have been made on battery safety models but achieving predictive accuracy across a wide range of conditions continues to be extremely difficult. From a numerical perspective, the obstacles are numerous. Multiple physics can potentially be involved and interact with one another, electrochemistry, thermal, mechanical, fluid dynamics and so forth. The question of modeling scale also invariably arises. Is it reasonable to imagine a numerical model resolved at the micro scale being later used in a macro model such as car crash simulation?

• Exploring the Potential of ARM Processors: Evaluating LS-DYNA Performance for Cloud-Based High-Performance Computing

  Eric Day

  In the realm of high-performance computing (HPC), x86_64 architecture has traditionally dominated, driven by its robust performance and extensive software support. However, recent benchmarks indicate the emerging viability of ARM processors for compute-intensive workloads, particularly when running LS-DYNA software. This study explores the performance of LS-DYNA on ARM-based chips, specifically evaluating its effectiveness on Amazon Graviton in the HPC cloud environment and Apple M, Cavium ThunderX2, Ampere Altra, Fujitsu A64FX and Amazon Graviton in standalone computing. Power efficiency, high throughput, cost-effectiveness, and scalability position ARM processors as compelling options for cloud-based LS-DYNA computations.

• Explosive Welding of Light Weight Metal Sheets

  Yamato MATSUI , Masahiko OTSUKA, Takeshi HINATA, Shigeru ITOH - Kumamoto University, Erik CARTON - TNO-Prins Maurits Laboratory

  The technique of explosive line welding is one of the processing techniques and it can connect similar and dissimilar metal sheets using large energy of explosive during very short time. In this study we try to weld lightweight metal sheets by experiment and work on the numerical simulation concerning a series of the phenomenon. Materials involved are aluminum alloys Al5052-O, 6061T6 and 6M83, magnesium alloy AZ31B-O and commercially pure titanium TP270C. After welding samples were taken to perform shear strength test and the welding interface was analyzed using optical microscopy. The strength test indicates a remarkable good bonding between similar welded metals. Particularly, the use of line welding shows a high strength to explosive mass ratio, making it a good candidate to be scaled up and used in commercial applications.

• External blast load on structures – Empirical approach

  G. Le Blanc, M. Adoum, V. Lapoujade - CRIL TECHNOLOGY

  Modeling structures response to blast loads interests more and more people concerned about industrial accidents and/or terrorism. Today, two approaches are available: one can either use an ALE model (*ALE) with a lagrangian-eulerian coupling (*CONSTRAINED_LAGRANGE_IN_SOLID) or a pure lagrangian approach where an analytical loading of the structure replaces the computation of the propagation. The lagrangian approach allows the use of a much smaller model since only the structure is modeled. This kind of approach, based on the empirical model described in the TM5-855 US army handbook (CONWEP), is currently available in LS-DYNA (*LOAD_BLAST). However, it is limited to the treatment of the explosions of hemispherical charges on the ground or spherical charges in the air without ground interaction. In many cases, the interaction of the shockwave with the ground induces blast reinforcement. CRIL TECHNOLOGY, in order to get more precise blast load evaluation with a pure lagrangian approach, has developed a new user-loading model (evolution from *LOAD_BLAST) to take into account new abacuses for TNT and for reflecting coefficients, ground effects and Mach stem. Major evolutions are based on empirical models described in the TM5-1300 US army handbook. This new user-loading, in many cases leads to more precise and more conservative load while retaining a reasonable model size as the method is purely lagrangian.

• F - Ma = 0 The unique certitude in Aerospace ?

  Dr. Yves GOURINAT - ENSICA Professor Mechanics & Space Techniques

• Facilitating Virtual Testing at an Industrial Level with Simulation Data Management

  Marko Thiele, Alexandru Saharnean, Ferenc Leichsenring, Masahiro Okamura, Alexander Gromer, Andre Haufe

  From an industrial or productive standpoint, the scale of simulation models, the number of involved simulation model components, and the complexity of the utilized processes with a vast amount of data are at a level that is challenging to manage manually. The introduction of virtual testing adds to the complexity of the development process and the quantity of data to be handled. Consequently, the use of a Simulation Data Management (SDM) system for this purpose can be advantageous or even indispensable. The introduction of virtual testing can be accomplished in several steps. The initial step is the automation of data preparation, encompassing both input data and produced result data for both the OEM and the testing authority. Subsequent steps involve the implementation of individual processes and security mechanisms against data manipulation. This paper primarily addresses the initial step and outlines a methodology for achieving the objective of safeguarding against data manipulation and intellectual property (IP) infringement by OEMs.

• Facing Future Challenges in Crash Simulation Engineering – Model Organization, Quality and Management at Porsche

  Marcel Koch, Dr. Ing. h.c. F. Porsche AG;, Steffen Mattern, DYNAmore GmbH;, Robert D. Bitsche, SCALE GmbH

  Numerical simulation has become an indispensable tool in car crash analysis, reducing the number of physical experiments and driving the engineering process. While the predictive capabilities of the simulation models have greatly increased in recent years, so has the level of detail, the complexity and the number of load cases analyzed. Dealing with these complexities can become a burden distracting engineers from their main task: the vehicle development process. It is therefore essential to provide automated, standardized and robust simulation processes in order to support the engineers throughout all steps of pre-processing, simulation and post-processing.

• Failure model calibration of a DP1000 dual phase steel using solid and shell elements for crash simulation

  Florence Andrieux, Silke Klitschke, Andreas Trondl

  With the trend towards lightweight construction, advanced high-strength steel (AHSS) is increasingly being used in automotive structural components. Since the ductility of high strength steels is relatively low, damage behaviour of these materials must be accurately modelled. In automotive structures AHSS components are usually discretized with shell elements. With the increase of computation capacity attempts with solid elements are made to capture the loading state more accurately, especially after necking. For this reason, it is convenient to develop a method which enables a systematic model calibration from the 3D to the 2D loading situation. The failure strain of metallic materials depends on stress state. In the past years several studies have shown that the stress triaxiality is not sufficient to describe failure and empirical models were extended to consider the effect of Lode parameter. Recently it was also shown that the amount of bending seems to influence failure, namely i.e. the failure strain increases with the amount of bending.

• Failure modeling of a self piercing riveted joint using LS-DYNA

  Silke Sommer - Fraunhofer Institute for Mechanics of Materials IWM, Johannes Maier - LuK GmbH & Co. KG

  Besides the basic product requirements, the aspect of energy efficiency is in the center of automobile engineering. A mixture of different light weight materials like aluminium and higher strength steels, called multi-material mix, is used increasingly to fulfill these requirements and reduce the weight of the vehicles. Hence the challenges for the joining technique are increasing. Mechanical joining techniques like self piercing riveting have great potential to fulfill this challenge. In particular the joints are the highest loaded parts during crash loading and overloading situations and have to be modeled in crash simulations. Joints are modeled with simplified elements in crash simulations due to efficiency. The simplified models should be able to reproduce the deformation and failure behavior as well as the energy absorption of the joints with less computational cost but with adequate accuracy. In this paper the modeling possibilities in LS-Dyna are investigated for a self piercing riveted joint of aluminium sheets. Beams, eight-noded hexahedrons, hexahedron clusters and constrained elements have been used for a simplified modeling of the riveted connection. The material models MAT_SPOTWELD, MAT_SPOTWELD_DAIMLER, MAT_ARUP_ADHESIVE, MAT_COHESIVE_ MIXED_MODE_ELASTOPLASTIC_RATE and the constrained models CONSTRAINED_SPR2 and _SPR3 have been tested with the simplified rivet model. The failure models are based on forces and moments, on normal, shear and bending stresses, on stresses and fracture energies and on forces and displacements for the constrained SPR models. The model parameters were determined by simulation of specimen tests under tension, lap-shear, peel and combined loading and by fitting the measured force vs. displacement curves. The different numerical results are compared concerning the measured load bearing capacities and energy absorption. The comparison showed that the hexahedron element with MAT_COHESIVE_MIXED_MODE_ELASTOPLASTIC is the most promising model for self piercing riveted joints in aluminium sheets because of the good description of the measured force vs. displacement curves and energy absorption under tension and lap-shear loading. The weakness of this model is the insufficient modeling of the peel loading and the lack of a possibility to control mixed mode loading. The paper gives a recommendation for further developments of modeling self piercing riveted joints.

• Failure Modeling of Unreinforced and Fiberreinforced Thermoplastics

  P. Reithofer, B. Hirschmann, T. Schaffranek (4a engineering)

  In the last years the demands of the automotive industry have led to a strong interest in a more detailed virtual description of the material behavior of thermoplastics. More and more complex material models, including damage and failure, have to be characterized, while keeping the importance of gaining material data quickly in mind. Currently material and failure modeling in crash simulations typically deal with simple von Mises visco-plasticity (*MAT_024) and equivalent strain failure criteria, which cannot describe the complex material behavior of plastics. Past developments have focused on the yield behavior under different load situations (tension, shear, compression), which are implemented in more complex material models like *MAT_SAMP-1 for thermoplastics as well as *MAT_215 for fiber reinforced thermoplastics.

• Failure Models of Plastics - Material Characterization for *MAT_ADD_EROSION (DIEM)

  A. Fertschej, B. Hirschmann, M. Rollant, P. Reithofer (4a engineering GmbH)

  The tensile test is a standard testing method for many different materials to determine elasticity, plasticity and failure. Due to DIC (digital image correlation) these tests are time consuming and in the case of dynamic testing also cost intensive. To characterize the dynamic deformation behavior dynamic bending tests on 4a impetus are a cost-efficient alternative.

• Failure Modes Analysis in the Crash Barrier Simulation

  Lei Hou - CELLBOND, UK

  The technology of FEA modelling is expanding rapidly in the field of automotive safety analysis. From the pre/post-processing for the material impact to the mathematical equations in the solver the non-linear analysis becomes a vital part of the simulation. In this paper we trace the development of experimental data validated-analysis method for the Cellbond honeycomb barrier model by using LS-Dyna software. The utilization of the database from IIHS and Advanced-MDB cores in the estimation of solid material parameters enables our simulation well framed into the impact criterion corridors. Over the past 10 years in Cellbond Ltd, at least three general categories of experimental-analysis methods can be identified in the failure modes classification: (1) Forced-Normal Mode Tests, (2) Dynamic Frequency-Response Filtration and (3) Mathematical Estimate against Theory. FEA impact-analysis method for each of these categories can be incorporated as multiple-input concept in one way or another. Historically, the failure modes characteristics of structural mechanical systems have been estimated by techniques that fall into either the first or second category. The forced-normal mode tests method has always been included in the repeated single inputs concept while the Dynamic Frequency-Response Filtration method, until recently, only involved the application of multiple-input. This paper presents a generalised FEA-modes-analysis method with emphasis on the including the refinements of the previous methods. The FEA-modes- analysis method, that fall into the last two categories are composite approaches that utilize the static load-curve estimation algorithms based upon structural models and include multiple-input concepts. The current FEA developments in the areas of dynamic simulation are encouraging.

• Failure of Thermoplastics – Part 1: Characterization and Testing

  A. Fertschej, P. Reithofer, M. Rollant (4a engineering)

  Complex material models are much more used nowadays. The reasons are the increasing usage of plastics in high security relevance automotive and the resulting demand for virtual modeling including damage and failure.

• Failure of Thermoplastics – Part 2 Material Modeling and Simulation

  A. Fertschej, M. Rollant, P. Reithofer (4a engineering)

  Complex material models are much more used nowadays. The reasons are the increasing usage of plastics in high security relevance automotive and the resulting demand for virtual modeling including damage and failure.

• Failure Prediction for Polymer Products with Short Fiber

  J. Takahashi, Y. Fujita (Asahi Kasei)

  Polymers have been often used as structural materials under mechanically severe conditions instead of metals. We usually use FEM simulation when we design polymer products. The failure prediction of impact is especially important because its effect for reduction of development duration and number of trial products cannot be disregarded. The failure prediction has been investigated for a long time [1][2]. We generally start impact simulations using elasto-plastic material such as MAT_024 by giving stress-strain curves with strain rate dependency. We often add our own research achievement about material model by the user defined material models which LS-DYNA offers us to improve prediction accuracy. We developed the isotropic material model based on damage of polymers and introduced it into LS-DYNA by using user subroutine “*MAT_041-050”. We found many good coincidences between experimental impact test and numerical results with our material model. After that, we found the reason why we got good coincidence by simulation with isotropic material model was that glass fibers in the structural specimen of these experimental tests align well at the impact area. Therefore, we decided to start simulations for structural specimens with various fiber distributions. Differences between the isotropic simulation results and anisotropic results are recognized. The importance for taking fiber orientation into account in impact simulations is known [3]. Then, we conducted the experimental impact tests using structural specimen made of Polyamide 66 with 35 weight% short fiber (ASAHI-KASEI LeonaTM 14G35). We set different fiber distribution by giving two gate types in injection molding. In this paper, the effect of introducing fiber distribution is discussed.

• Fan Blade Bird Strike Analysis Using Lagrangian, SPH and ALE Approaches

  Alexander A. Ryabov, Vladimir I. Romanov, Sergey S. Kukanov - Sarov Engineering Center, Yuriy N. Shmotin, Pavel V. Chupin - NPO Saturn

  Fan blade bird resistance is one of the most important certification requirements for modern jet engines. The development test to meet the requirement is difficult and costly experiment. The expenses can be significantly reduced by using the numerical simulation of fan blade bird strike problem in the design of jet engine. The common technique for such simulations is modeling of bird as a solid cylinder or ellipsoid with material properties similar to water. The paper presents some results of fan blade bird strike analysis using LS-DYNA Lagrangian, SPH and ALE approaches to model the bird. The main objectives of the investigations are to compare the results obtained by means of different approaches and to find out the advantages and disadvantages of every approach.

• Fan Blade Bird-Strike Analysis and Design

  Thomas J. Vasko - Pratt & Whitney

  Bird ingestion is a costly and difficult engine test to perform. It is also one of the most challenging and complex analytical investigations in engine design. The capability to model bird ingestion effects is, therefore, critical to the success of any competitive jet engine program. LS-DYNA has been used in the design and analysis of fan blades for bird-strikes. Descriptions of the bird and blade models used in the analyses along with the contact algorithms used to describe their interaction will be presented. In addition, comparisons of analysis and test results from bird-strikes on fan blades will also be presented.

• Far side crash correlation and sensitivity study for virtual testing

  Roland Schirmer, David Ide, Carlos Gonzáles

  In 2024 the monitoring phase of the virtual far side occupant assessment is going to start. The vehicle manufacturer will carry out the physical sleds and virtual tests. Variations of the impact angle and the seat position are going to be assessed with purely virtual tests. The car manufacturer has to show that the correlation level of his simulation model is sufficient. For that the ISO score rating according to ISO/TS18571 and the selected ATD (‘dummy’) injury criteria are used on the two validation tests. To be prepared for this challenge, Stellantis put together a cross functional, international CAE team of methods development and safety department members. The task was to test if the existing model content and the level of detail in the subsystems fulfill all performance requirements and to identify the key enablers to reach the correlation targets.

• Fast New Methodology for Regulatory Test Simulation

  Velayudham Ganesan, David Piesko, Jean-Louis Duval - ESI Group

  Preparing a simulation model for a crashworthiness or occupant safety regulatory test is often a time consuming task. This paper describes a new methodology that significantly reduces this modeling time, down to minutes. Using predefined FMVSS standards, EASi-Process allows users to access ready made test templates for common runs (such as FMVSS 201, 208, 581...). With the integration of EASi-Process, EASi-CRASH DYNA, premier pre and post processor for multi-body and finite element occupant safety simulations using LS-DYNA, allows the user to select the type of test to perform and the structure to perform it on, and the technology takes care of the rest. This technology, combined with EASi-CRASH DYNA, has proven to have dramatic benefits regarding cost and productivity for engineers and the enterprise.

• Fast Road Barrier Car Safety Calculations on a Cray XC

  J. Cholewinski, A. Findling, G. Clifford (Cray), M. Piechnik (Stalprodukt)

  Despite progress achieved in the last decade, 70 people die and more than 650 are seriously injured every day on Europe’s road. As one of the most cost-effective safety infrastructure solutions available to policy makers, vehicle restraint systems can greatly contribute to alleviating the consequences of road accidents and increase levels of safety on European roads.

• Fast Study of Multiple Sizes Helmets and Design Shape Optimization using LS-DYNA, LS-OPT and DEP MeshWorks

  Armand Leglise, Antoine Guilpin, Charlotte Michel, Vincent Lapoujade, Matthieu Seulin

  For obvious security reasons, wearing a helmet is highly recommended when riding a bike or a skateboard. In order for the manufacturers to design safe helmets some regulations have been established and must be respected before any market release. The process enabling to meet the regulation targets can be quite long considering the numerous impact points and test configurations that have to be repeated for each helmet size. The use of simulation and the appropriate tools can be a real asset to save time and reduce experimental tests while increasing security and comfort. Indeed, the numerical simulation offers the opportunity to explore more designs and test almost an infinite number of impact configurations. Especially when the numerical tools are powerful enough to significantly speed up the product development process.

• Faster Metal Forming Solution with Latest Intel Hardware & Software Technology

  N. Meng (Intel Corporation), J. Sun (LSTC), P. J. Besl (Intel Corporation)

  Reducing part development time & cost and increasing quality & productivity have always been important goals in the metal forming industry. Quick response to frequent mould change is challenging metal forming simulation engineers in the modern high efficiency production environment. To achieve these goals, a requirement for nearly instant numerical simulation of metal forming processes is emerging. Unfortunately, poor scalability and slow I/O due to adaptive remeshing as well as long waiting times in corporate HPC job queues are all bottlenecks to instant numerical simulation of metal forming processes. Three optimized ®workstation solutions using new Intel hardware and software technology are proposed. The proposed solution addresses these issues through code optimization using the latest ® ® ® 1Intel compiler technology, Intel Xeon processor E5-2600 product family processor, the 2nd ®generation Intel Solid State Device (SSD) technology, and the new Advanced Vector Extension 3(AVX) instruction set. The proposed solution allows metal forming simulations to be run on a local workstation with promising turnaround times. The performance of optimal configurations is discussed for real customer workloads in this paper.

• FAT SIDE IMPACT DUMMY MODLES REMARKS ON USAGE AND POTENTIAL PITFALLS

  Ulrich Franz, Peter Schuster, Werner Schmid, Oliver Graf - DYNAmore GmbH

  Detailed finite element side impact dummy models of the USSID, EUROSID, and ES-2 have been developed in cooperation with the German Association for Automotive Research (FAT) during the last 5 years. All models are validated using tests at material and component levels as well as fully assembled models. The models are used by nearly all car manufacturers worldwide who use LS-DYNA for occupant safety simulations. The paper describes modeling aspects of the dummies and gives an overview of their performance in sled tests. Furthermore emphasis is put on difficulties and potential pitfalls that might arise during the everyday work with the models in predicting occupant injury risks. In addition to the knowledge gained during the development process, experiences from the support for and the consulting with the FAT dummy models are presented.

• Fatigue assessment of an adhesively bonded EV battery enclosure, using LS-DYNA implicit tools

  David McLennan, Michael Magnier, Simon Hart

  Adhesively bonded aluminium structures are becoming increasingly popular within the automotive industry. Bonded connections are continuous, and therefore can avoid the stress concentrations which arise in discrete connections such as spotwelds, rivets or bolts, and thus have the potential to perform better from a fatigue perspective. However, bonded structures have their own challenges to analyse, particularly for predicting fatigue life, where limited data exists in the public domain.

• Fatigue Life Prediction of Composite Adhesive Joints using LS-DYNA®

  Ala Tabiei and Wenlong Zhang, Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA

  Composite and adhesive joints are used increasingly in the automotive industry and an active research area is the fatigue analysis of adhesive joints. In this paper, a methodology to predict the fatigue life of adhesive joint is proposed and implemented into LS-DYNA with the joint modeled using a user-defined cohesive material. Fatigue crack growth rate is used to obtain the fatigue damage accumulation rate in cohesive zone model. Our method is verified by numerical simulations of two commonly used adhesive joints in the automotive industry: single lap joint and stepped lap joint. The predicted S-N curve fits well with the experimental data.

• FE analysis and parameter optimisations of anisotropic material models for sheet metal materials using Full-Field-Calibration

  J. Jung, W. Rimkus, S. Mouchtar, J. Schlosser, M. Schmiedt (Hochschule Aalen)

  Forming simulation models and the associated material characterisation are important factors when representing the increasingly complex deep drawing operations. Especially in context of automotive components, the finite element analysis ensures producibility prior to pilot series and minimises the risk of wasting resources by predicting the material behaviour as accurately as possible, such as plastic, thermal and anisotropic behaviour. For the representation of the plastic material deformation during forming, material models like Barlat or Hill, representing the real material behaviour as precisely as possible, must be implemented in the simulation. For this purpose, the model needs to describe occurring effects of the material such as anisotropy or further effects.

• FE Analysis of Contact Interaction Between Rigid Ball and Woven Structure in Impact Process

  Alexey I. Borovkov, Igor B. Voinov - St.Petersburg State Polytechnical University

  The current paper presents the results of finite element solution of the problems simulating contact interaction between woven structures and striker in the form of rigid ball. The woven structure is represented by a great number of the fibers braided in such way that each of them can come into contact interaction with others. In this paper the analysis results for ball impact direction effect on the woven structure dumping properties was demonstrated. For simulation of the impact process and subsequent multiple contact interaction between woven structure fibers FE mesh containing about 1 million degrees of freedom was used. The efficiency of contact algorithm realization in finite element software LS-DYNA is visually presented. The zone with largest contact pressure and redistribution of contact interaction zone in impact process was analyzed

• FE approach to evaluate the dynamic friction coefficient for the transient phase of rubber-ice sliding interaction

  R. Leonardi, S. Scalera (DYNAmore Italia), A. Scattina (Politecnico di Torino)

  The improvement of tractive performance on ice is one of the most challenging aspect in the nowadays tire industry. For this reason, a model which can predict the friction coefficient on ice can be useful in the winter-tire design. However, the highly multiphysics nature of the interaction between rubber and ice [1-4], as well as the magnitude of the dimensions involved make the development of a numerical model a quite complex issue. In this work, a first step for the prediction of the friction coefficient on ice is proposed using the finite element method. The subject of this analysis is the transient phase of the sliding interaction between a rubber block and an ice surface. The User Define Friction module of LS-DYNA has allowed to implement the suitable friction law for contacts with ice, widely used in the literature [3, 5], which follows a microscopic approach and it is based on a viscous formulation. Considering again the dimensions involved and the duration of the transient phase, it is impossible to directly validate the model through experimental detection [3]. However, in the subsequent steady-state phase, which involves higher amounts of water and longer time, the experimental measurements are easier. To compare the results, in the literature an indirect procedure was used in order to provide a qualitative validation, using the strict link between the transient phase and the steady-state one. The final comparison between the LS-DYNA results and the literature results has shown a good correlation level.

• FE Fracture Prediction on Edges of Punched Holes

  Dr Janka Cafolla, David P. Norman (Tata Steel UK Limited)

  Many industry sources identified fracture from holes and edges as a key knowledge gap for fracture prediction of AHSS and UHSS grades. Ford Aachen with MATFEM cooperation [1] has shown an importance of including fracture failure models into their finite element (FE) simulations especially when designing with UHSS such as Boron Steel. Hole expansion coefficient (HEC) is one of the ways to characterise the edge cracking of metals. Many studies investigated the best way of predicting the fracture using HEC in their experimental work [2], [3] combined with FE simulation [4]. In the later one a simplification for an FE simulation is done such that only 2D model is utilized. Since the study examines the area around the hole in quite a detail, the mesh density is too high for general use in crash FE model of a full vehicle. In forming simulations HEC and forming limit curve (FLC) are often the criteria for inspecting the possibility of material failure. In crash simulations neither HEC nor FLC are generally used. More suited are the phenomenological fracture models which are more applicable for a wider range of engineering problems. There are now a number of these fracture models available. Examples of some of these fracture models are from Gurson [5] and various extensions to Gurson, Dell and Gese [6], Wierzbicki [7] and Wilkins [8]. Dell and Gese use CrachFEM material model developed by MATFEM [9]. Tata Steel adopted the use of CrachFEM material in past few years. Horn [10] and his colleagues at Tata Steel Research and Development have investigated several methods for measuring and analysing the data needed as input variables in CrachFEM material cards. CrachFEM material data are now available for the customers in AURORA material database. Norman and Buckley [11] have successfully used this data in their automotive virtual development process. Their test-FE correlation gave very promising results. CrachFEM material model has therefore become a winning tool for developing a simple method of fracture prediction in a crash event. A simple rectangular test specimen with a hole in the middle was designed such that it was possible to use the optical strain measurement system - ARAMIS. This gave an opportunity to correlate not only force-displacement curves between the test and FE simulations but also strain development around the hole.

• FE Implementation of AA6xxx Series Aluminium Pre-Strain Dependent Strengthening Response During Paint Bake

  S. Jurendic, Z. Liang, R. Burrows (Novelis); S. Saha (RWTH Aachen)

  As the drive for light-weight materials in the automotive industry increases, so does the use of heat-treatable AA6xxx series aluminium alloys in both body panels and structural components. These alloys have a distinct advantage in that they can be formed in a soft state of temper and later on heat treated in the paint bake process to achieve a higher overall component strength. The material maintains good formability throughout the forming process and achieves high strength in the final heat treated component. With this, a new set of challenges has arisen in finite element modelling of components made from these materials, which now has to account for the material being in different metallurgical states during production versus final application (e.g. crash analysis). To further complicate things, the strengthening response of the material during final heat treatment is highly dependent on the amount of pre-strain that locally arises in the material during forming. In this work, a microstructural model is applied to predict the yield strength of the material in a deformed and paint baked condition. The model considers influences of pre-strain, time and temperature on the microstructural transformations taking place in the material during heat treatment. These results are then implemented in a finite element model of a deformation process. Both the microstructural model as well as the component level finite element model are validated for the case of tensile test measurements at different levels of pre-strain and heat treatment parameters typical of an automotive paint bake process. To consider more complex deformation, a further validation case of a cylindrical deep drawing process is presented. Finally, simulation of a static axial tube crush test is carried out to illustrate the influence that inclusion of the pre-strain dependent paint bake response has on the simulation results.

• FE Modeling of Innovative Helmet Liners

  D. Hailoua Blanco, A. Cernicchi - Dainese S.p.a, U. Galvanetto - University of Padua

  A key component of a safety helmet is the energy absorbing liner, which absorbs the greatest portion of impact energy during an accident. The aim of the present work was to study innovative structures for energy absorption that minimize the likelihood of head injuries for standard impact cases. The innovative helmet liner consists of an ABS plastic lamina with deformable cones on it. Energy is absorbed via a combination of folding and collapsing of the cones. The main advantage that such liner may introduce over common EPS pads is that it allows a better optimization of energy absorption for different impact sites and configurations. Numerical crash simulations of the novel liner employed in a ski helmet were carried out with LS-DYNA®. The model reproduced the testing conditions defined by the standards EN1077. Experimental and numerical results were compared and possible causes of discrepancies were discussed. The finite element model so validated paves the way for a future numerical parametric optimization of the novel structure. Keywords: Helmet, Crashworthiness, Energy Absorbing Structures, Drop testing

• FE-Application in Aircraft Structure Analysis

  Dr.-Ing. Matthias Hörmann - CADFEM GmbH, Germany

• FE-MODELING OF SPOTWELDS AND ADHESIVE JOINING FOR CRASHWORTHINESS ANALYSIS

  A. Haufe , G. Pietsch - Dynamore GmbH, Germany, M. Feucht, S. Kolling - DaimlerChrysler AG, Germany

  The increasing demands with regard to the predictive capabilities and the exactness of crash simulations require more and more investigations into numerical models in order to capture the physical behavior reliably. Steps towards this goal are the usage of finer meshes which allow for a better geometrical representation and more sophisticated material models which allow better prediction of failure scenarios. Another important playground towards improved crash models is the area of connection modeling. Validation in this area is usually closely related to very detailed models which cannot be easily translated into a crash environment due to time step restrictions. Therefore, representative substitute models have to be developed and foremost validated. The aspect that failure of the connections has to be considered as well adds another dimension to the complexity of the task. The present paper highlights the conflict between predictive capability, capture of physical reality and manageable numerical handling. Another aspect of the paper is the attempt to raise the awareness of the topics verification and validation of numerical models in general. This concept is illustrated using latest developments for modeling of spotwelds and adhesive bonding in LS- DYNA.

• FE-MODELLING OF HYDRODYNAMIC HULL-WATER IMPACT LOADS

  Ivan Stenius, Anders Rosén - KTH Centre for Naval Architecture

  This paper considers finite element modelling of the hydrodynamic loads in hull-water impacts. The commercial FE-code LS-DYNA is used with a multi-material arbitrary Lagrangian-Eulerian formulation and a penalty contact algorithm. The great advantage of this modelling technique is that it enables the modelling of the instantaneous fluidstructure interaction. A difficulty is however the selection of appropriate modelling parameters. A method to rationally select appropriate modelling parameters is discussed and briefly described. Convergence of the pressure distribution is presented and discussed. Pressure distributions and loads are favourably compared with other theoretical methods and with experiments.

• FEA - Calculation of the Hydroforming Process with LS-DYNA

  Michael Keigler, Herbert Bauer - Aalen University, Germany, David K. Harrison, Anjali K. M. De Silva - Glasgow Caledonian University, United Kingdom

  The automotive industry is constantly searching for product improvements concerning weight reduction and the need for corrosion resistance. Currently aluminium alloys are of special interest because of their low density of 2.76 g/cm3, and good corrosion resistance. The disadvantage of aluminium alloys is poor formability in comparison to steel. Therefore, new forming methods are demanded such as the “tube hydroforming” process, which has been reasonably successful in creating complex parts in aluminium alloys. This process involves the concurrent pressurization and axial compression of a tube, causing the material of the tube to flow into a die cavity, achieving the form of the final component shape. Lightweight and complex forms of aluminium components have been achieved successfully, when the process parameters are calculated and controlled accurately. Due to its various shaping and design possibilities, the hydroforming process has been used for more than 10 years in the automotive industry for the production of complex carrier structure units. The requirements e.g. the shaping possibilities, respectively, the design space of unit geometry, the expansion relationship, as well as the maximum plastic deformation possibility has risen constantly over that time. This requires ever larger efforts to fulfil these requirements under the compliance of fixed time and cost goals. The contents of this work are the task of the FEA- Simulation of the hydroforming process. It consists in a general feasibility study for the forming behaviour of the semi-finished product and/or the tools. Due to the complex connections of the process influence parameters the non- linear finite elements (LS-DYNA) offers the condition to fulfil these requirements, in particular regarding plausibility check, general feasibility as well as adjusting quality and tolerance field promises (formation of wrinkles, springback, form and position tolerances). A quality increase can additionally be derived accompanying the increase of manufacturing security for series production by the evaluation of the manufacturing simulation.

• FEA - Simulation of Bending Processes with LS-DYNA

  Peter Gantner, Herbert Bauer - Aalen University, Germany, David K. Harrison, Anjali K. M. De Silva - Glasgow Caledonian University, United Kingdom

  Over the past few years new car body concepts have space frame structures. The consequent application of space frames results in a reduction of weight, fuel consumption, and costs of a body while maintaining a high safety standard. These structures consist mainly of closed profiles and hydroformed components. Prior to the hydroforming process, the profiles are usually pre-bent. The bending of tubes is a crucial step in the hydroforming process chain. For a successful hydroforming the bending demands high precision, reproducibility, and process reliability. These bending operations are frequently performed with parameters which are already on their limit. For the design of hydroformed components it is unavoidable to ensure all process steps by means of FEA (Finite Element Analysis) - simulation. Especially for a precise prediction of the feasibility of the bending process and the subsequent process steps it is necessary to consider all parameters and tools (e.g. mandrel) in the simulation. This results in very complex simulation models which make great demands on the simulation programs concerning precision, contact and friction. The contents of this paper deals with the finite element simulation of complex bending processes by using the non- linear simulation program LS-DYNA. In the first part of the paper the simulation of the Rotary Draw Bending with a mandrel is shown by means of a practical component and the results from simulation are compared and validated with experiments. In the second part the new Free-Bending technique is introduced by an example. Both bending techniques offer new possibilities and application ranges in the field of hydroforming.

• FEM for Impact Energy Absorption with Safety Plastic

  Iulian Lupea, Joel Cormier, Sital Shah - The Oakwood Group

  For the engineering design process to benefit from finite element modeling (FEM), it must adequately represent any condition being studied. This paper presents methodologies for using the LS-DYNA non-linear finite element solver to model a patented energy absorbing technology called SafetyPlastic®. SafetyPlastic® offers a performance, cost, and mass competitive energy management solution, and has been embraced by the automotive industry in both head and side impact occupant protection applications. It is characterized by a connected plurality of structural recesses that repeatedly give resistance, and then buckle when impacted. Due to the nature of SafetyPlastic® and its preferred manufacturing method, a somewhat unique FEM challenge presents itself. The paper provides details related to: • Modeling the strain rate dependent polymeric materials used in SafetyPlastic® • Using a proper mesh size; • Specification of the mesh pattern suitable for the assumptions made when manually inputting thickness profile; • Predicting the wall thickness profile for thermoformed designs via FEM with T-SIM® software; • Transferring and mapping data between T-SIM® and LS-DYNA for FEM; • Selecting the proper responses to evaluate the FEM versus experiment results; • Validating the FEM via quasi static and dynamic impacts with a flat plate; • Validating the FEM via dynamic impacts with a free motion headform; • Assessing the correlation of FEM with experimental results; • Optimizing the size and shape of recesses to promote annular buckling. The data presented show that FEM with LS-DYNA can be performed today with a degree of accuracy that will aid upfront SafetyPlastic® design. This leads to the prospect of conducting optimization studies via design of experiments or otherwise without prototype tooling expenses. However, there is room to improve the overall synchronization of a simulated SafetyPlastic® impact response with a real one. Work to refine and better the FEM methodology is an ongoing effort.

• FEM study of metal rolling in grooved rolls

  D.V. Shevchenko, D.Yu. Saraev - Siemens Corporate Technology, A.I. Borovkov, D.L. Nesterenko - St. Petersburg State Polytechnical University

  LS-DYNA was used to model the rolling process in grooved rolls. One-pass and two-pass (with rotation of the metal sheet at 90° a fter first pass) rolling in grooved rolls, as well as four-pass rolling in plain rolls and various combinations of these two types of rolling were simulated. With the help of finite-element analysis we estimated the influence of the areas of deformation hardening on the stress-strain state of metal sheet. The developed finite-element model allows analyzing stress-strain state of the system caused by variation of parameters, such as: geometry (design), rolling speed, physical- mechanical properties of materials, temperature and friction coefficient. Process parameters can be fine-tuned to achive the desired improvement of physical-mechanical properties of the rolled metal .

• FEM-BEM Coupling with Ferromagnetic Materials

  T. Rüberg, L. Kielhorn, J. Zechner (Tailsit)

  Eddy current problems are typically modelled by a combination of Ampère’s law, Ohm’s law, the non-existence of magnetic monopoles and Faraday’s law of induction. Using a magnetic vector potential A, such that the magnetic flux intensity is given by B = curl A, we end up with the equation σ ∂ t A + curl ν(A) curl A = Js [1]. Here, Js are applied source currents, ν(A) the magnetic reluctivity whose dependence on A implies the possible non-linearity of the material behaviour, and σ is the electrical conductivity. In most applications, the domain of interest consists of conducting (e.g. metal parts) and non-conducting regions (e.g. air). In the non-conducting regions, the part σ ∂ tA is dropped from the equation and the model is that of magnetostatics.

• FEM-PROCESS-SIMULATION OF HYDROMECHANICAL DEEP-DRAWING

  Matthias Aust - University of Stuttgart (Germany)

  The FEM-Process-Simulation of metal forming processes has been proven to be useful during the design stage of components and toolings. However, this is not valid for relatively new processes, e. g.. hydromechanical deep-drawing. Hydromechanical deep-drawing is related to conventional deep-drawing, but the process is quite different. When using hydromechanical deep-drawing, instead of a rigid female die a counter pressure pot is used to form the sheet metal against the punch. The process modeling and application of conventional deep-drawing is a well-known process with a great amount of practical and theoretical experience. Therefore a large database of knowledge exists. In contrast to conventional deep- drawing, for hydromechanical deep-drawing the practical and theoretical knowledge is limited. Since the application of hydromechanical deep-drawing is becoming more interesting (e.g. for the production of niche cars), the demand of theoretical and practical knowledge is increasing

• FINITE ELEMENT ANALYSIS OF SLIDING CONTACT BETWEEN A CIRCULAR ASPERITY AND AN ELASTIC URFACE IN PLANE STRAIN CONDITION

  S. Subutay Akarca, Dr. William J. Altenhof, Dr. Ahmet T. Alpas - University of Windsor

  Wear is a critical phenomenon affecting service life of products. Therefore, wear prediction is an important concern of study. In this study, sliding contact was modeled using LS-DYNA. FEMB was used to create the geometry of the model and the input file was manually modified as necessary. Studies were done to test, calibrate, and validate the model in LS-DYNA before simulation of the sliding wear by an asperity sliding over a plastically deforming and work hardening material surface. A flat half-space with dimensions of 30μm depth and 100μm width is subjected to sliding contact by a semicircular asperity of radius 10μm. The third dimension of the model was assumed to be infinite and therefore a plane strain condition was studied. Elastic indentations were performed to validate the finite element model. Elastic indentation results were compared to the predictions of the Hertz theory of elastic contact. With the help of mesh convergence study the best conditions to simulate sliding wear were determined. Mesh dimensions, hourglass control, contact algorithm, application of the normal load, and mass scaling were the main issues of the study. According to the Hertz theory, the maximum contact pressure and the maximum shear stress were calculated as 2684 and 805 MPa for the conditions studied. Numerical models predicted 10-15% higher values higher values for those stresses. However, normalized stress values show a very good agreement with the theoretical predictions.

• Finite element analysis of Polymer reinforced CRC columns under close-in detonation

  Benjamin Riisgaard NIRAS Consulting Engineers, Denmark, Anant Gupta, Priyan Mendis, Tuan Ngo - The University of Melbourne

  Polymer reinforced Compact Reinforced Composite, PCRC, is a Fiber reinforced Densified Small Particle system, FDSP, combined with a high strength longitudinal flexural rebar arrangement laced together with polymer lacing to avoid shock initiated disintegration of the structural element under blast load. Experimental and numerical results of two PCRC columns subjected to close-in detonation are presented in this paper. Additionally, a LS-DYNA material model suitable for predicting the response of Polymer reinforced Compact Reinforced Concrete improved for close-in detonation and a description of the LS-DYNA multi-material Eulerian method for modeling the blast event is also presented in this paper.

• Finite Element Analysis of Unanchored Structures Subjected to Seismic Excitation

  Sreten Mastilovic - Bechtel SAIC Company, LLC

  The objective of this analysis is threefold: (1) to determine the residual stress distribution in two unanchored structures, the waste package and drip shield, subjected to seismic excitation; (2) to estimate the extent and spatial distribution of the area of the two structures for which the residual first principal stress exceeds certain limits; (3) to determine whether or not separation of interlocking drip shield segments occurs during the vibratory ground motion.

• Finite Element Analysis of Stresses Due to Normal and Sliding Contact Conditions on an Elastic Surface

  Anantha Ram B.S., Joachim Danckert, Torben Faurholdt - Aalborg University, Denmark

  Wear prediction necessitates the investigation of elastic stresses developed in the workpiece material due to impact and sliding of abrasive particles in tribological contact situations. LS-Dyna implicit finite element analysis is used to investigate these contact stresses in the workpiece material under imposed Hertzian pressure loading. A line contact condition (cylindrical body on a plane surface) is assumed and the predicted stress field is compared with analytical solutions. The model is parametric, two-dimensional and built in LS-Ingrid in terms of semi contact width ‘ ’. Application of hertz pressure and implicit control cards are some of the issues of this study. The study is a preliminary step in the extension of the model where the workpiece will be modeled with a thin hard layer/coating under the same contact situations. It is found that the finite element model developed, predicts the elastic stresses in close agreement with the theoretical results and the model can be suitably extended for analyzing contact situations of layered systems.

• FINITE ELEMENT ANALYSIS OF SUPERPLASTIC FORMING PROCESS USING LS-DYNA

  Haryanti Samekto - Universitaet Stuttgart, Karl Roll - DaimlerChrysler AG

  Superplastic forming process has been a standard manufacturing process in aircraft industry and its applications in other industries are increasing. Superplasticity is utilised in forming parts which can not be produced technically or economically using materials with ordinary ductility. As superplastic deformation should be carried out under certain strain rate in which m value is maximal, the finite element method is applied to model the forming process in order to optimise the process through generating a pressure-time curve. In this paper, the dynamic explicit solution procedure was taken as an alternative solution due to its efficiency, as most of the current simulations of SPF used static implicit. The material parameters of Aluminium alloy 5083 SPF were first determined and the creep constitutive model was chosen. The finite element analysis results from dynamic explicit were verified with experimental results and then compared with static implicit. The simulation of bulge forming process with the geometry of a cup was conducted. The effects of m value and friction coefficient value were investigated.

• FINITE ELEMENT ANALYSIS OF DUCTILE FAILURE IN STRUCTURAL STEEL SUBJECTED TO MULTIAXIAL STRESS STATES AND HIGH STRAIN RATES

  T. Børvik, O.S. Hopperstad, S. Dey, M. Langseth - Norwegian University of Science and Technology, T. Berstad - LSTC

  Notched specimens of the structural steel Weldox 460 E have been tested at high strain rates in a Split Hopkinson Tension Bar. The aim was to study the combined effects of strain rate and stress triaxiality on the strength and ductility of the material. It is further considered important to obtain experimental data that may be used in validation of constitutive relations and fracture criteria. The force and elongation of the specimens were measured continuously by strain gauges on the half-bars, while the true fracture strain was calculated based on measurements of the fracture area. Optical recordings of the notch deformation were obtained using a digital high-speed camera system. Using image processing of the digital images, it was possible to estimate the true strain versus time at the minimum cross-section in the specimen. The ductility of the material was found to depend considerably on the stress triaxiality. Non-linear finite element analyses of the notched tensile specimens at high strain rates have been carried out using LS-DYNA. A computational material model including viscoplasticity and ductile damage has been implemented in LS-DYNA and determined for Weldox 460 E steel. The aim of the numerical simulations was to assess the validity of the material model by comparison with the available experimental results.

• Finite element analysis of localised impact loading on short glass fibre- reinforced polyamide engine oil pan subjected to low velocity impact from flying projectiles

  Zakaria Mouti, James Njuguna - Cranfield University, Keith Westwood, Darren Long - Eaton, Automotive Group

  This paper investigates low velocity impact involving a glass fibre-reinforced polyamide engine oil pan as part of a complete new development of thermoplastic components. The assessment of the impact resistance has driven the need to employ LS DYNA for finite element modelling in order to virtually benchmark and predict the strength and fracture behaviour of stressed plastic parts. In order to develop a reliable predictive capability and to validate simulations, complete components were manufactured by injection moulding techniques for the experimental samples. Low velocity impact investigations were carried out using a gas gun and a falling weight tester in order to simulate impact events to which the oil pan is subjected whilst in operational service. This was intended to point out damage tolerance and failure mechanisms likely to occur in the structure. The study results show the significant contribution of the design in terms of shock absorption. Specific oil pan design with protective ribbing combined with a superior material considerably improves the impact resistance. The paper provides results and discussions on experimental and finite element analysis investigations before concluding with some remarks.

• Finite element development and early experimental validations for a three dimensional virtual model of a bus

  Prof. Dr. Mariano Pernetti, Dr. Salvatore Scalera - AMET ITALY

  Road safety barriers in Europe have to fulfil the European standard EN 1317, which defines a set of crash tests for each safety barriers containment levels. Full scale tests of vehicle collision against road safety barriers have a huge importance to assess the outcomes of real accidents and, more in general, to identify barriers and vehicles features which influence crashworthiness in a meaningful manner. On the other hand, this kind of tests is really expensive and many parameters are hard to control and measure. Due to the aforementioned reasons, numerical analysis of vehicles collisions against safety barriers has become a convenient methodology that supports and integrates the previous one, especially considering the continuous technological hardware/software progress. The paper presents finite element (FE) development and the early experimental validations for a three dimensional virtual model of a bus. The main objective of this research activity is to create a simplified FE model of this kind of vehicle useful to simulate collisions against road safety barriers in a wide range of impact conditions. Particular attention was paid in modelling features of the bus such as frame, suspensions and tyres, which influence in a meaningful manner the behaviour of the vehicle during a collision. The bus model complies with the requirements for the homologation of H2-type barrier (test TB51), in accordance with European standard EN1317. To evaluate the general behaviour of the finite element model of the bus, two different impacts were simulated, (i) against a concrete wall and (ii) against an H2-type barrier. These collisions represent two situations extremely different considering transformation of vehicle kinetic energy. Indeed, concerning the impact against concrete wall, a large part of kinetic energy changes in vehicle internal energy causing a collapse in a wide portion of the bus. Differently, in the case of impact against a steel barrier, vehicle kinetic energy is transformed in device internal energy, but the impact against posts stresses tires, axles and suspensions in a huge manner. Besides, the roll angle is grater than the one registered during the collision against the wall, because the average high above ground of the global action is less than the previous one, causing a larger upsetting moment and a significant stress on the suspensions. Due to previous reasons, the collisions against a concrete wall and against a steel barrier, represent excellent preliminary tests to verify the numerical robustness of the FE model of the bus and to evaluate the general good behavior of the vehicle during collisions in a wide range of impact conditions.

• Finite element development and early experimental validations for a three dimensional virtual model of a bus

  Prof. Dr. Mariano Pernetti, Dr. Salvatore Scalera - AMET ITALY

  Road safety barriers in Europe have to fulfil the European standard EN 1317, which defines a set of crash tests for each safety barriers containment levels. Full scale tests of vehicle collision against road safety barriers have a huge importance to assess the outcomes of real accidents and, more in general, to identify barriers and vehicles features which influence crashworthiness in a meaningful manner. On the other hand, this kind of tests is really expensive and many parameters are hard to control and measure. Due to the aforementioned reasons, numerical analysis of vehicles collisions against safety barriers has become a convenient methodology that supports and integrates the previous one, especially considering the continuous technological hardware/software progress. The paper presents finite element (FE) development and the early experimental validations for a three dimensional virtual model of a bus. The main objective of this research activity is to create a simplified FE model of this kind of vehicle useful to simulate collisions against road safety barriers in a wide range of impact conditions. Particular attention was paid in modelling features of the bus such as frame, suspensions and tyres, which influence in a meaningful manner the behaviour of the vehicle during a collision. The bus model complies with the requirements for the homologation of H2-type barrier (test TB51), in accordance with European standard EN1317. To evaluate the general behaviour of the finite element model of the bus, two different impacts were simulated, (i) against a concrete wall and (ii) against an H2-type barrier. These collisions represent two situations extremely different considering transformation of vehicle kinetic energy. Indeed, concerning the impact against concrete wall, a large part of kinetic energy changes in vehicle internal energy causing a collapse in a wide portion of the bus. Differently, in the case of impact against a steel barrier, vehicle kinetic energy is transformed in device internal energy, but the impact against posts stresses tires, axles and suspensions in a huge manner. Besides, the roll angle is grater than the one registered during the collision against the wall, because the average high above ground of the global action is less than the previous one, causing a larger upsetting moment and a significant stress on the suspensions. Due to previous reasons, the collisions against a concrete wall and against a steel barrier, represent excellent preliminary tests to verify the numerical robustness of the FE model of the bus and to evaluate the general good behavior of the vehicle during collisions in a wide range of impact conditions.

• Finite element dynamic simulation of whole rallying car structure: Towards better understanding of structural dynamics during side impacts

  E. Nassiopoulos and J. Njuguna - School of Applied Sciences, Cranfield University

  Side impact accidents against a tree or pole remain the most dangerous accident scenarios in rally cars. Statistical data shows that 52% of the fatalities between 2004 and 2009 concern crashes against a rigid pole by the track sides, whilst among those more than 60% were side impacts. Despite the present scientific efforts, rallying cars side impacts are still among the least understood primarily due to limited space between the occupant and door sill, evolving safety regulations and vehicle dynamics. In this study, finite element dynamic characteristics of the whole car were studied. The finite element model consisted of the whole car structure and 241 parts including the engines, tyres and the suspension members with 4 different element types and 7 material models. All structural parts were modelled as low-carbon steel with the piecewise-linear-plasticity material model (mat 24). The tyres were modelled with the Blatz-Ko rubber material (mat 07) whilst also rigid and other materials (mat 020, 01, 09, S01 and S02) were used to represent different parts of the model, as the suspension members, suspension links and the engine. A rollcage and two racing seats were modelled with four-node shell elements and the use of piecewise-linear-plasticity and composite-damage materials respectively. A semi-cylindrical pole of 200mm diameter was also designed and modelled as a rigid body. The model was used to first investigate the dynamics of the crash, and later run a wide range of simulations and parametric studies in the cage, the car’s floor and the seats. The important findings from the study are presented, conclusions drawn and scope for further development outlined.

• Finite Element Investigation of Injury Risks of Immature Pelvis and Femur in Pedestrian Impact

  Ming Shen, Anil Kalra, Runzhou Zhou, Xin Jin, King H. Yang (Wayne State University), Binhui Jiang (Hunan University), Yajing Shu (Chongqing University)

  Car-to-pedestrian collision is a major cause of injury and death for children. Due to the different anthropometric features of a child compared to an adult, children present more injuries in the pelvic region (including the proximal femur) than adults do. It was hypothesized that the epiphyseal growth plates (GPs) in the hip region may affect the stress distribution and further influence the injury pattern seen in children. To quantitatively address this issue, finite element (FE) simulations of an SUV-to-pedestrian impact was conducted. The human model was built based on a 10-year-old whole-body FE model (CHARM-10) embedded with the GPs at the pelvic region (triradiate cartilages at the bottom of acetabulum) and the proximal femur (femoral head GP and greater trochanter GP). The GP geometries were taken from clinical images and medical study reported in the literature. The material properties were derived from a set of optimization procedures using the published experimental results. The results of the parametric studies revealed that the GPs have significant effects on the mechanical responses and injury outcomes. More specifically, the hip joint contact force was reduced, implying a reduced stiffness of the pelvic girdle; the risks of fractures at the femoral shaft and acetabulum are decreased; the risk of pelvic ramus fracture is elevated. Further simulations explained the detailed effect of each of the three GPs at the hip region.

• Finite Element Modeling and Analysis of Crash Safe Composite Lighting Columns, Contact-Impact Problem

  Alexey Borovkov, Oleg Klyavin, Alexander Michailov - St.Petersburg State Polytechnical University,, Martti Kemppinen, Mikko Kajatsalo - Mikkeli Polytechnic Research Centre YTI, Finland

  Three Finnish associates, Tehomet Ltd, Fibrocom Ltd and Mikkeli Polytechnic Research Center YTI developed an internationally awarded energy absorbing lighting column product family in 2005. The design and dimensioning were assisted with static FEM computations, preliminary impact tests and full-scale impact tests made by YTI. The CompMechLab helped these associates in product optimization and further development by developing lighting column FE-models with sufficient energy absorbing properties, by fitting the model to obtain similar deceleration curves with real car crash tests, and to provide recommendations concerning the design of new, higher columns. Developed fully 3-D CAD and FE models of different column types featured the simulation of the following nonlinearities: dynamic impact at different vehicle speeds, plasticity in column and vehicle parts, contact interaction between the simulated objects and progressive damage in column laminates. 3-D FE model of the impact car was based on FHWA/NHTSA National Crash Analysis Center prototype including radiator, engine, front and rear suspensions, brake system and many other parts with ability of contact interaction and nonlinearities in material behavior. Prototype design was modified to get approximate similarity with the Peugeot 205 car used in the experiments. Column 3-D FE model includes column stand, reinforced composite laminates and bracket with lanterns (single or double). Al together 216 different materials were used in the FE- model of the car and the lighting column. The resulting simulated deceleration curves allowed calculating Head Injury Criteria – conforming Federal Motor Vehicle Safety Standard – and estimating safety reliability for all columns crush tests. Computed Head Injury Criteria values combined with maximal deceleration values proposed the constructions to be safe ones.

• Finite Element Modeling and Validation of Guardrail Steel Post Deflecting in Soil at Varying Embedment Depths

  Nauman M. Sheikh, Akram Y. Abu-Odeh, Roger P. Bligh - Texas A&M University System

  This paper presents finite element modeling and validation of roadside guardrail steel posts deflecting in soil. The soil model was validated for posts embedded at various depths. Prior to finite element modeling, several drop- pendulum impact tests were conducted to determine the actual response of the soil-post interaction in dynamic impacts. A decrease in the depth of the post significantly increased the deflection in soil, which complicated the modeling of the soil behavior. Finite element model of the post and soil setup was developed to capture the post-soil behavior observed in the tests. Two material models, Geological Cap and Jointed Rock, were evaluated for use in the finite element model. Additionally, Lagrangian and Smoothed Particle Hydrodynamics (SPH) methods were briefly compared to determine suitability of use. It was determined that the Jointed Rock material model is better capable of capturing the soil-post interaction in cases where the post embedment was reduced and the resulting soil deformation was large.

• Finite Element Modeling of Reconstructed Vehicle Rear Seats with Adult Male ATDs

  Keegan Yates, Costin Untaroiu (Virginia Tech)

  Most car crash fatalities occur in the front seats, so experimentation and regulations involving car crash occupant protection typically focus on the front seats. Because of this, the safety of the front seats has increased greatly over the years, and in some circumstances, the front seats now perform better than rear seats. This represents a problem because the rise of ridesharing transportation and automated driving systems has the potential to increase rear seat occupancy by adults, which could result in an increase in injury and death. To help inform the design of new vehicle rear seat safety systems, it is important to understand the performance of current vehicle rear seats with adult occupants. The rear seats of eight vehicles were reconstructed from scans of the seat surfaces as well as the seat pan and seatbelt components. Seat foam material properties were taken from quasistatic tests of each seat. The THOR and Hybrid III male 50th percentile ATD FE models were positioned and settled in each seat. The vehicles frontal NCAP crash pulse as well as a less severe pulse were applied to each vehicle in LS-DYNA®. Injury likelihood was assessed by a summary of the AIS3+ risk curves for the head, neck, chest, and femurs. Overall, the results with a frontal NCAP pulse ranged from a near certainty of AIS3+ injury to around a 35% chance. Additionally, the best performance was seen with vehicles that contain pretensioners and load limiters in the rear seats. These results indicate that such technologies may be necessary in the rear seat to improve crash performance. Additionally, these results have helped select a range of vehicles for further experimentation and identified variables of interest for further simulation.

• Finite element modeling of the ITER superconducting cables mechanical behaviour using LS-DYNA code

  A.S. Nemov , A.I. Borovkov - St.Petersburg State Polytechnical University, B.A. Schrefler - University of Padua

  Superconducting cables are one of the key technical solutions used for generation of strong magnetic field in modern tokamaks. It is very important for engineers to be able to predict the mechanical deformations of superconducting cables because superconductivity depends on strains, temperature and magnetic field. Superconducting cables for ITER the International Thermonuclear Experimental Reactor [1] currently under construction, have a complex structure that makes any analytical estimations hardly applicable. This paper presents the application of LS-DYNA [2] finite element code to the solution of different mechanical problems for ITER superconducts. Stretching, twisting and transverse compression are considered and results are compared with analytical estimations where possible.

• Finite element modeling of the ITER superconducting cables mechanical behaviour using LS-DYNA code

  A.S. Nemov , A.I. Borovkov - St.Petersburg State Polytechnical University, B.A. Schrefler - University of Padua

  Superconducting cables are one of the key technical solutions used for generation of strong magnetic field in modern tokamaks. It is very important for engineers to be able to predict the mechanical deformations of superconducting cables because superconductivity depends on strains, temperature and magnetic field. Superconducting cables for ITER the International Thermonuclear Experimental Reactor [1] currently under construction, have a complex structure that makes any analytical estimations hardly applicable. This paper presents the application of LS-DYNA [2] finite element code to the solution of different mechanical problems for ITER superconducts. Stretching, twisting and transverse compression are considered and results are compared with analytical estimations where possible.

• Finite Element Modeling of Aluminium Honeycomb with Variable Crush Strength and Its Application in AE-MDB Model

  M. Asadi (Anglia Ruskin University), B. Walker, H. Mebrahtu (ARUP Campus (UK)), M. Ashmead (Cellbond (A Division of Encocam Ltd.))

  Aluminium honeycomb blocks are often to gain differentiated crush strength pattern to represent variable behavior while subjected to static/dynamic deformation. Current article demonstrates the methodology to validate modeling techniques and implementing in a finite element model for the Advanced European Mobile Deformable Barrier (AE-MDB). AE-MDB v3.9 side impact barrier has been investigated in present paper. The FE model is then examined using experimental data from a set of full-scale tests. Component tests have been designed and performed to establish the material characteristics for the FE model to maintain the crush strength pattern within the specified design corridors. The model then has been analysed using LS-DYNA© under certain boundary conditions according to the test specifications and the results have been compared to the physical test data. The barrier has been subjected to the Flat-Wall and Pole tests while the obstacles were blocked against the barrier on a mobile trolley. The methodology is then certified through comparison of the deformation pattern and numerical information with the experiments.

• Finite Element Modeling of the Arresting Gear and Simulation of the Aircraft Deck Landing Dynamics

  Dmitriy Mikhaluk, Igor Voinov, Prof. Alexey Borovkov - CompMechLab of St. Petersburg State Polytechnical University

  Deck arresting gear is a special aero-carrier unit that is destined to provide an efficient arrestment of the deck jet-fighters of masses 10-25 tons with high landing velocities between 180 and 240 km/h. Main elements of the modern arresting gear are a cable and a hydraulic system. During deck landing the jet-fighter grasps the cable with a hook and draws it. The cable is threaded between a system of blocks, that are forming a block-and-tackle mechanism, designated to transfer the jet-fighter pull to the hydraulic braking machine. In the latter the kinetic energy of the fighter is transferred to the heat and then dissipated. In the current work a full-scale LS-DYNA model of the deck arresting gear is created. The model contains all basic elements of the real prototype and is used to analyze the dynamic behavior of the arresting gear with different arrestment conditions. Due to the feedback control system, several characteristics of the arresting gear elements vary with some of run-time changing parameters. Standard capabilities of LS-DYNA do not enable performing simulation of such a complex system and by that reason a Delphi code is developed. The code allows managing of LS-DYNA solution and automatically makes multiple restarts during the simulation to change the definition of stiffness and damping curves, describing the arresting gear parts. The developed model is used to obtain parameters of the arresting process – fighter displacement, velocity, acceleration vs. time, as well as pressure in the hydraulic system and tensile force in the cable.

• Finite Element Modeling of the Arresting Gear and Simulation of the Aircraft Deck Landing Dynamics

  Dmitriy Mikhaluk, Igor Voinov, Prof. Alexey Borovkov - CompMechLab of St. Petersburg State Polytechnical University

  Deck arresting gear is a special aero-carrier unit that is destined to provide an efficient arrestment of the deck jet-fighters of masses 10-25 tons with high landing velocities between 180 and 240 km/h. Main elements of the modern arresting gear are a cable and a hydraulic system. During deck landing the jet-fighter grasps the cable with a hook and draws it. The cable is threaded between a system of blocks, that are forming a block-and-tackle mechanism, designated to transfer the jet-fighter pull to the hydraulic braking machine. In the latter the kinetic energy of the fighter is transferred to the heat and then dissipated. In the current work a full-scale LS-DYNA model of the deck arresting gear is created. The model contains all basic elements of the real prototype and is used to analyze the dynamic behavior of the arresting gear with different arrestment conditions. Due to the feedback control system, several characteristics of the arresting gear elements vary with some of run-time changing parameters. Standard capabilities of LS-DYNA do not enable performing simulation of such a complex system and by that reason a Delphi code is developed. The code allows managing of LS-DYNA solution and automatically makes multiple restarts during the simulation to change the definition of stiffness and damping curves, describing the arresting gear parts. The developed model is used to obtain parameters of the arresting process – fighter displacement, velocity, acceleration vs. time, as well as pressure in the hydraulic system and tensile force in the cable.

• Finite Element Modeling of Cable Hook Bolts

  John D. Reid - Brian A. Coon - University of Nebraska-Lincoln

  Component analysis of any complex system is frequently required to determine the true accuracy of a finite element model. Although a composite system may yield the “correct” final results, the system is not truly accurate unless individual components are performing correctly. The purpose of this paper is to describe the component testing and finite element modeling of a standard 5/16”-18 x 2” galvanized shoulder hook bolt used in cable barrier systems. These bolts hold the cable to the post of a cable barrier system. During a vehicle impact with the system, the cable loads many of the restraining hook bolts in different directions. Several of the hook bolts will reach their bending yield limits and “open up,” allowing the cable to disengage. This is designed behavior which allows the cable to capture the impacting vehicle. Successful modeling of these bolts is essential to have an accurate finite element model of a complete cable barrier system.

• Finite Element Modeling of Preloaded Bolt Under Static Three-Point Bending Load

  Ken-An Lou, William Perciballi - ArmorWorks

  The objective of this project was to develop innovative lightweight mine-protected fasteners for blast protection appliqués. Blast protection appliqués are used on tactical and combat ground vehicles as a method of deflecting or mitigating the effects of anti-vehicular mine blasts or attack by Improvised Explosive Devices (IEDs). A critical and weakest component of these appliqués is the fastener joints. Currently, industrial bolts are commonly used for attaching blast protection appliqués to vehicles due to simplicity. However, under blast conditions, these bolts can often shear off causing secondary fragments and projectiles which may impact the vehicle and crew, causing additional damage and injury to the vehicle personnel. This study focused on conducting three-point bending tests to evaluate different bolt materials. Bolt preload or stress initialization was simulated via LS-DYNA® Implicit with two separate analyses. Also a similar two-step initial strain analysis was performed using NEiNastran. The simulated results will be compared with test data. Future work will include finite element modeling and testing of fasteners under dynamic, ballistic, and blast loads.

• Finite Element Modeling of Material Damage in Axially- Loaded Aluminum Tubes with Circular Hole Discontinuities

  Bryan Arnold, William Altenhof - University of Windsor

  Finite element simulations of the axial crushing of extruded aluminum tube structures were conducted using LS-DYNA in order to investigate their load management and energy absorption characteristics. The structures under consideration were made from aluminum alloy 6063-T5 and contained dual centrally located circular hole discontinuities. The results of the finite element simulations are compared to the results of quasi-static experimental crush tests conducted on structures of similar nominal geometry and material properties. Due to the presence of significant cracking and splitting in the crushing modes observed during the experimental crush testing, a material model employing damage mechanics was assigned to the structure models. This material model was calibrated using the experimental crush testing results as well as tensile tests conducted using specimens extracted from the extrusion stock material. A good correlation was observed between the results of the quasi-static crushing experimental results and the results of the finite element simulations. The experimental peak buckling loads of the structures were predicted to within 10% by the finite element simulations.

• Finite Element Modeling of Strip Curvature During Hot Rolling

  Anup A. Kuldiwar

  Finite element techniques have been used to decouple some of the major causes of strip curvature in the finishing stages of a hot strip mill. A plane strain elastic-plastic finite element model (HYPERMESH5.0) is used to predict the direction and severity of strip curvature caused by asymmetrical factors at each pass of the finishing mill. Predictions have been obtained using the elastic-plastic facilities of LS-DYNA Version 960. A full factorial experiment was then designed and performed, using finite element predictions, to identify which asymmetrical factors are most influential to strip curvature and to determine the interactions, between factors. The result show that some of the asymmetrical factors are significant to strip curvature, but their influence depends on the rolling pass. This study will allow the rolling operator to identify which asymmetrical factor may be causing strip curvature and, thus, provide a suitable course of action.

• Finite Element Modeling of Co-Mingled Glass/Thermoplastic Fabrics for Low-Cost/High-Volume Composites Manufacturing

  Patricia P. Buso, James A. Sherwood, Julie Chen - University of Massachusetts-Lowell

  The stamping of co-mingled glass/thermoplastic textiles for manufacturing relatively low- cost/high-volume structural composite automotive parts, e.g. truck beds and floor pans, is extremely attractive. These textile materials have yarns comprised of polymer fibers interwoven with the structural fibers, e.g. fiberglass. By heating the textiles in an oven, the polymer fibers melt and infuse the yarn, thereby removing the need to apply the resin in a separate step. The heated fabric can subsequently be stamped into a structural shape. The difficulty these fabric materials exhibit is that their deformation response exhibits both geometrical and materially nonlinear behaviors. The candidate material being evaluated in this study has a weave structure. The stamping mold for the current research is a hemispherical shape. Several samples of the candidate material were stamped to a variety of depths and over a range of temperatures to see how the sides of the material draw in as the part is being stamped. Splits on the hemispherical portion and wrinkles on the adjacent flat surface were observed. Several material models inherent to LS-DYNA were evaluated and a user-supplied subroutine was incorporated to consider the weave architecture. The correlation of the experimental and finite element results are presented.

• Finite element modelling and validation of the honeycombs for automobile crash MDB and ODB

  Hui Yang, Qianbo Liu, Liangfu Yu (Shanghai Motor Vehicle Inspection Centre), Lin Li (Automotive College of Tongji University)

  Honeycomb materials are widely used in automotive crash tests. Typically, it is the main components of the ODB (Offset Deformable Barrier) and MDB (Mobile Deformable Barrier) stipulated in ECE Regulation No.94 and No.95 on automotive crash test. These two kinds of honeycombs or barriers are also adopted by Chinese regulations. The accuracy and efficiency are most important for the CAE analysis of automotive crash simulation. In the earlier the solid elements is mainly employed for honeycomb modelling due to the limitation of computer calculation. The challenge of the solid element modelling is to overcome the hourglass energy, computational stability and local deformation simulation, etc. Recently, with the rapid improvement in computer hardwires, the shell elements are [1][2][3] more and more used for modelling the honeycomb . The shell model for honeycomb has some advantages such as high computational stability, lower hourglass energy and good simulation for detailed local deformation. The shell models of honeycomb can be found from the LSTC Inc. and [3] Wang . In China, the majorities of auto manufacturers still use the solid model of honeycomb from overseas commercial models such as ARUP and ESI honeycomb models. The shell model of honeycomb hasn’t yet been widely used because it is in grow-up stage and needs more validations for its accuracy. Meanwhile, some data or parameters in these commercial models is invisible and cannot be handled. Furthermore, some problems were found in the actual CAE applications, such as too strong glue, excessively hard character of the whole honeycomb and abnormal energy, and so on. On the other hand, many auto manufacturers still insist on developing own honeycomb models so that they can grasp the whole analysis simulation. Based on the experimental data and other literatures, this paper presents the FE models of ECE ODB and MDB developed by LS-DYNA®. By means of whole vehicle crash validations, these two models can give a good accuracy and computation stability. All the codes of these models will be opened to the public so that it will be helpful for auto engineers to comprehend the details of the honeycomb model and to improve the models.

• Finite element modelling of textile-soft material interaction using 3D/4D scan data

  Ann-Malin Schmidt, Yordan Kyosev

  The interaction between textile and soft material occurs in different areas. It can be found in the clothing, medicine or automotive sector. In this paper the textile-soft material interaction has been investigated using the example of the breast-bra interaction. 4D scan data of a test person dressed with a bra and unclothed were acquired in two scan poses. The scans were analysed by cross section comparisons. A finite element model was developed from these scans. Three different meshing methods were modelled. A FEM model of a bra compressing the female breast was successfully developed. The breast deformation is modelled the best with a solid body model. In the validation comparison of the modelled breast deformation and the original breast deformation, a very good agreement can be seen.

• Finite element modelling of the static axial compression and impact testing of square CFRP tubes in LS-DYNA3D

  Dimitrios Papapostolou - National Technical University of Athens

  LS-DYNA3D finite element code was used for investigating the compressive properties and crushing response of square FRP (Fibre Reinforced Plastic) tubes subjected to static axial compression and impact testing. Several models were created in order to simulate a series of static and dynamic compressive tests that were performed in the National Technical University of Athens (NTUA) using carbon FRP tubes, that were featured by the same material combination (woven fabric in thermosetting epoxy resin) and external cross-section dimensions but different length, wall thickness, laminate stacking sequence and fibre volume content. Modelling the three modes of collapse observed during the experimental works (i.e. progressive end-crushing with tube wall laminate splaying, local tube wall buckling and mid-length unstable crushing) was the primary goal of the simulation works. The agreement between calculations and test results regarding the main crushing characteristics of the tested CFRP tubes –such as peak compressive load and crash energy absorption– and the overall crushing response of the tubes was quite satisfactory as the finite element models were refined several times in order to achieve optimum results.

• Finite Element Modelling of a NiTi SMA Wire

  W. L. H. Wan A Hamid, L. Iannucci, P. Robinson (Imperial College London)

  The development of a Finite Element Model of a NiTi shape memory alloy (SMA) wire in a commercial explicit finite element software, Ls-Dyna, is presented. A user-defined material (UMAT) model has been developed by implementing one of the earliest one-dimensional SMA constitutive models, the Tanaka model [1], into Ls-Dyna through a FORTRAN code. The aim is to apply this model to develop a SMA-actuated morphing wing. Morphing has attracted considerable attention among researchers for the past few decades because of the potential of providing optimum flight conditions at various flight missions. A combination of the morphing wing with smart materials such as SMAs offers further advantages such as a significant reduction in weight and system complexity, compared to an actuation achieved by mechanical motors or hydraulic systems. The simplest example of an actuated structure is presented, that is a SMA wire connected to a linear spring in series. The SMA wire was modelled as a beam element with one integration point, which is equivalent to a truss element, whereas the linear spring was modelled as a discrete element. One complete heating-cooling cycle was applied on the SMA wire. Upon heating, a reverse transformation (martensite-to-austenite) occurred, caused the wire to shorten and consequently extended the spring. Hence the stress in the wire increased while the SMA strain decreased until the end of the transformation. Upon cooling, a forward martensitic transformation (austenite-to-martensite) took place and reduced the stiffness of the wire. As a result, the spring contracted and the wire extended, and so the stress decreased while the SMA strain increased until the end of the transformation. This finite element prediction of the thermomechanical behaviour was compared to an analytical solution for small displacement, and a close agreement was achieved. A parameter analysis was then carried out to analyse the dependence of the thermomechanical behaviour on several parameters such as the length and cross-sectional area of the SMA wire, as well as the spring stiffness (stiffness of the actuated structure). As expected, the FE model showed that the recovery stress (maximum stress at the end of heating cycle) increased whereas the recovery strain (maximum strain at the end of heating cycle) decreased with increase in the SMA length and spring stiffness, and with decrease in the SMA cross-sectional area. The user-defined SMA model was further tested as a design tool to morph a pre-curved corrugated plate. The results showed that for large diameter SMA wires, increasing the number of SMA wires in each cell resulted in a small increment in the tip deflection. A parallel configuration is preferable than a ‘V’ configuration for cells consisted of two SMA wires, because slightly higher tip deflection can be achieved. This is mainly due to the influence of the SMA length on the thermomechanical behaviour. Finally, the SMA model was applied on a morphing wing consists of six corrugated plates between its leading and trailing edges. The resulted trailing edge vertical deflection is 36.6 mm, about 10% of the chord length. In conclusion, this work provides a foundation for future exploration of SMA-actuated morphing wings using Ls-Dyna, such as an optimization of the internal structure using LS-OPT, and fluid-structure interaction (FSI) simulations to include the effect of incoming air flow on the movement of the wings

• Finite Element Modelling of Biomechanical Dummies- The Ultimate Tool in Anti-Whiplash Safety Design?

  Waldemar Z. Golinski, Richard Gentle - The Nottingham Trent University

  Nowadays, people purchasing a new car are no longer simply looking for attractive styling, good performance and an efficient, reliable engine; one of their main concerns is now also the safety of the car. During the last decade, significant progress in improving car occupant safety has been made through the use of safety devices, such as airbags and advanced seat belts, as well as the construction of the car body itself. However, much still needs to be done to satisfy increasingly stringent legislation and public demand. This work deals with the problem of whiplash injuries that traditionally, due to difficulties in diagnosis, have been very difficult to investigate let alone prevent. Nevertheless, some progress has recently been made in this field. We have previously presented a simplified dynamic FE model of the cervical spine which, using comparisons with the latest experimental work on fresh cadavers, allowed the mechanism of injury to be defined. Subsequently the spine model was used in conjunction with a simple occupant model to investigate the possibility of creating a design tool for anti-whiplash devices. This work, although only preliminary, indicated that the approach of grafting a fully biomechanical FE model of the cervical spine onto a conventional FE model of a crash test dummy could produce an unrivalled analysis of a whiplash injury situation. In the present work a new, more advanced biomechanical FE model of the head–neck complex has been created and combined with the Hybrid III FE dummy model, which is the industry standard tool for occupant safety. The principal modifications are the method of modelling soft tissues and the representation of the inertial properties of the head to achieve a more realistic behaviour of the model.

• Finite Element Models for European Testing: Finite Element Models for European Testing: Side Impact Barrier to WG13 Pedestrian Impactors to WG17

  Trevor Dutton - Arup Solihull, UK

• Finite Element Simulation using SPH Particles as Loading on Typical Light Armoured Vehicles

  Geneviève Toussaint, Robert Durocher - Defence Research and Development Canada – Valcartier

  Light Armoured Vehicles (LAV) are essential to transport troops and equipment in combat and high risk zones. The emergence of non conventional threats such as Improvised Explosive Devices (IED) implies a need to reassess armoured vehicle design to improve crew survivability. To do this DRDC has been developing new experimental facilities and has conducted experimental testing to study armoured vehicle structure subjected to near field blast loadings. Numerical models of the test facility were developed to assist the design of the experimental program and to accelerate the design of improved protection systems. This paper presents results of experimental and numerical analysis, in order to compare the numerical predictions with experimental results. In this study the smoothed particle hydrodynamics (SPH) technique was applied to model the loading on the vehicle structure.

• Finite Element Simulations of Blasting and Fragmentation with Precise Initiation

  M. Schill (DYNAmore Nordic AB), J. Sjöberg (Luleå University of Technology)

  By using blasting caps with electronic delay units, it is possible to control the time of ignition between the boreholes of a mine. This has opened up new possibilities to optimize the blasting in order to achieve a better fragmentation which would significantly reduce the costs for the mining industry. The potential benefits of being able to control the ignition times has been described by Rossmanith [1], where stress wave interaction should according to theory and experience result in higher fragmentation, throw, swelling and digability. This theory has in this work been tested through Finite Element simulations using the LS-DYNA software. The rock material used is Westerly granite, which has been modeled with the RHT material model and it uses damage mechanics to describe the fracture of the rock. Also, a 2D-fragmentation evaluation routine has been proposed that makes it possible to study the level of fragmentation in section cuts of the Finite Element model. A 3D FE-model of two boreholes was used to evaluate the influence from ignition times, borehole distance and the amount of explosives. The results show that there indeed is a stress wave interaction effect and in this region there is an increase in fragmentation. However, the zone with increased fragmentation is considered to be small. The main effect on the fragmentation comes from the distance to the explosive charge and the amount of explosives.

• Finite Element Simulations and Testing of Washington State Precast Concrete Barrier

  Akram Abu-Odeh, D. Lance Bullard - Texas Transportation Institute, Richard B. Albin - Washington State Department of Transportation

  Since the early 1970’s, the Washington State Department of Transportation (WSDOT) has used precast concrete barrier (as shown in Figure 1) for both temporary and permanent installations. The use of this barrier in high impact areas has increased through the years and is one of the primary barriers currently used on Washington State highways due to its inherit ease of installation and repair.

• First Steps Towards Machine-Learning Supported Material Parameter Determination

  D. Koch, A. Haufe (DYNAmore)

  Machine learning is becoming more and more part of our world. Even though most people have so far only passively used the possibilities of this technology, e.g. for search queries or product recommendations, many have surely already thought about how these new possibilities could support their work in the future. In this contribution, it is investigated if machine learning is suitable to support the process of material characterization. Through deep neural networks it is possible to "learn" nonlinear relationships between a set of input values and the corresponding output, also known as labels. As a proof of concept, it is examined whether the shape of the yield curve can be predicted based on force-displacement curves from simulated tensile tests. So, in a first step, a large number of tensile tests are simulated which differ in the shape of the yield curve. Here, for the description of the yield curve an approach according to Hockett-Sherby was used which provides 4 parameters for the definition of the shape. The force-displacement curves of these tests are used as the input and the parameters of the yield curve as labels. By considering the entire realistic range of all four parameters, the trained neural network should be able to provide the best matching set of parameters for a given force-displacement curve. For the prediction, of course, the initial and boundary conditions must be the same when generating the force-displacement curve, whether by simulation or in a real test. Of course, all initial and boundary conditions as well as all other assumptions and simulation settings are also learned from the neural network. Therefore a change of these parameters can for sure worsen the predictions considerably and can make a re-learning process inevitable. The long-term objective of this method and the vision of this work are to learn the possible spectrum of the whole material model in advance in order to be able to finally predict the material properties based on only a few experiments with minimal effort.

• Flexible Body Suspension System Modeling and Simulation Using MD Nastran SOL700 in VPG Environment

  Casey Heydari, Ted Pawela - MSC.Software Corporation, Tim Palmer, Arthur Tang - Engineering Technology Associates, Inc.

  Automobile durability and fatigue life prediction depend on road load generation approaches including proving ground testing, laboratory measurement and CAE simulations. Traditionally, the road load simulations are done with ADAMS using rigid body and modal flexible body approaches. With the newly available MD Nastran SOL700 capability, a new approach of using FEA-based flexible body modeling for suspension systems will be an attractive supplemental solution. MD Nastran SOL700 is an LS-DYNA based explicit solution which is capable to correctly simulate FEA flexible body structure, motions, and kinematics while accurately accounting for the material and geometric non-linearity of a suspension system. This paper will focus on the methodology development to enable efficient conversion from an ADAMS model in XML format into MD Nastran SOL700 or LS-DYNA format in ETA’s VPG environment. In the VPG environment, a rigid body suspension model can be easily changed to FEA based flexible body model for either MD Nastran SOL700 or LS-DYNA solution. A demonstration case will also be provided to illustrate the process and approach.

• Fluid added mass modeling in LS-DYNA and its application in structural vibration

  Yun Huang, Tom Littlewood, Francois-Henry Rouet, Zhe Cui, Ushnish Basu

  Many structures, machines, or devices are operated partially in water, like surface ships, vessels, semi-submersible platforms. Some others may work completely in water, like submarines. For any of them, water has an important influence on their dynamic response. For most cases, a strong coupling between structures and surrounding water is required to get a good simulation of vibration response of structures subjected to shock or wave loadings. Unfortunately, a fully coupled simulation involving both structures and water explicitly can be expensive. Besides, with the traditional finite element method, meshing a large volume water body and defining non-reflection boundary conditions (e.g., Perfectly Matched Layer [1]) on the truncated boundary can be challenging and needs some experience.

• Fluid Flow Modeling with SPH in LS-DYNA®

  Edouard Yreux, Livermore Software Technology Corporation

  A new Smoothed Particle Hydrodynamics formulation for fluid flow modeling has been added in LS-DYNA. A density smoothing algorithm based on kernel density estimation is implemented to correct for the well-known pressure oscillation issue that arises with traditional SPH schemes when modeling fluids. A Weakly-Compressible equation of state is adopted to ensure reasonable timestep restrictions while minimizing the compressibility effects of the fluid. The resulting formulation is particularly suitable for free surface flows and fluid-structure interaction problems. Two and three dimensional validation problems are presented, as well as qualitative comparisons with incompressible CFD results obtained with the ICFD solver of LS-DYNA.

• Fluid Slosh Behavior for Crashworthiness – A Modeling Approach Validated with Experimental Data

  Prabhu Selvaraj, Vikas Sanghavi, Srikanth Adya, Onkar Akolkar, Vedant Joshi, Jeremy Seidt

  FMVSS301 mandates fuel system integrity for vehicles post-crash, so a detailed assessment of the fuel system is needed to validate its integrity. Modeling the fuel tank assembly for vehicle crashworthiness is very challenging due to the fuel slosh phenomenon which occurs in the dynamic crash event. The fuel slosh behavior affects the overall dynamics of the fuel tank and its interaction with surrounding vehicle structures. Extensive studies can be found in the literature to improve fuel tank modeling. However, there is limited information related to modeling fluid’s free surface and the pressure profile imparted by the fluid on the tank during the crash event.

• Fluid Structure Interaction in LS-DYNA Using Lagrangian Interfaces, Automatic Re-meshing and Adaptivity

  Facundo Del Pin, Grant O. Cook, Jr. - Livermore Software Technology Corporation

  The present work discusses a new Fluid Mechanics approach that will be introduced in future versions of LS-DYNA to solve incompressible flows. The objective of this new formulation will be to solve fluid-structure interaction problems using Lagrangian interfaces. In this way large deformations of structures are treated in a more natural fashion making it simpler to define the physical domain. Furthermore the proposed approximation will also deal with free surfaces and breaking waves. In a Lagrangian approach the mesh of the discrete problem moves together with the material particles. Thus for large deformations a very robust and fast re-meshing tool is being created. This tool will be incorporated in the software and all the re-meshing operations will be done automatically. Another key feature of this solver is that given an error estimator the re-meshing steps will also adapt the mesh to provide error control within the fluid solver.

• Fluid Structure Interaction with *MAT_SOFT_TISSUE and EFG Elements

  Rudolf Bötticher - TMB GmbH

  This paper presents LS-DYNA 970.5434a transient simulations for the fluid- structure interaction (FSI) in a prototype biomedical duct. Standard and element free Galerkin (EFG) elements are compared for the nearly incompressible membrane out of *MAT_SOFT_TISSUE, which is a composite reinforced hyperelastic material. The coupling of a multi-fluid arbitrary Lagrangian Eulerian (ALE) solid domain to an EFG solid domain is possible and its LS-DYNA implementation keeps developing. The paper describes particularities of this coupling. The EFG simulation for nearly incompressible materials necessitates a non-default support of 1.4x1.4x1.4 or even higher for accurate results. The EFG simulation demands higher computation times than the standard formulation with reduced integration and type 6 hourglass control. An example is shown, in which the high ratio of the elastic moduli chosen for the fibers and the bulk of the soft tissue material generates a severe hourglass problem that only the EFG method can cope with. The standard formulation, however, is remarkably robust and it proves difficult generating an extreme situation where only EFG works and the solver run would abort otherwise. So the potential of the EFG method lies in the accurate prediction without introducing non-physical energy in the system for hourglass stabilization, in situations, where selective reduced or full integration show a too stiff behavior and reduced integration has a hourglass problem. Although LS-DYNA 5434a is already much faster than 5434, a more computational efficient implementation of EFG for solid elements is required. Therefore, the features of the LS-DYNA 971 beta version, which address this lack of performance, are assessed as well. The paper features an abstracted input deck.

• Fluid Structure Interaction Simulation of Hood Flutter

  James Dilworth, Ben Ashby, Peter Young, Arup

  Fluid structure interaction problems appear in a wide range of industries, including automotive, marine and aerospace. In the automotive industry, the drive to make components lighter can also reduce their stiffness, causing them to deflect significantly under aerodynamic loads. The deflections can affect the aerodynamic properties of the vehicle, cause dynamic fluctuations that are visible to the driver, or even lead to failure. The Incompressible Computational Fluid Dynamics (ICFD) solver in LS-DYNA® is well suited to simulating fluid structure interaction as the code provides a range of robust and easy to use coupling algorithms and both solid and fluid solver can be readily accessed from within the same simulation environment. This paper shows some of the capabilities in LS-DYNA for simulating hood flutter, which is a known fluid-structure interaction problem. Hood flutter is affected by the turbulent wake from preceding vehicles, the hood opening mechanism and the opening up of seals. This paper considers the feasibility of commercially feasible simulation of this complex automotive FSI phenomenon through the creation of a series of models which display how the important physical features of hood flutter could be modelled.

• Fluid Structure Interaction (FSI) Applications to Consumer Products

  Jean V. Seguro - The Procter & Gamble Co.

  Manufacturing consumer products and among them disposable absorbent products is very complex, not only due to the number of components that are assembled together, modified and packed but also because it has to be done at very high speed in order to compete in the ever more competitive disposable absorbent products industry. Creating models to represent such complex processes is very challenging for the above reasons and others like the very small thickness of the materials and their particular properties. Representing these processes using Finite Element Analysis (FEA) has been a growing practice at The Procter & Gamble Co. (P&G) for quite some time and in recent years complexity has been added to the models by including fluid representations, therefore developing Fluid Structure Interaction (FSI) models which in many cases are needed to better represent the processes we want to model. In this paper some basic settings of FSI models are described. By using the *Constrained_Lagrange_In_Solid keyword and other necessary keywords it is possible to simulate the interaction of the flimsy structures representing the disposable absorbent products materials with the air that surrounds them, while traveling at high speed. Then the paper goes on to showcase some of the models that have been successfully developed and validated (trim removal, folding and component ribbon handling), all of these models involve the interaction between flimsy structures and air. Validation of the models has been very important to gain confidence in the capabilities and some of the validation data is shared in this paper which shows great agreement between the models’ predictions and the data collected during the experiments. This paper demonstrates how FSI models developed using LS-DYNA® successfully represented manufacturing processes of disposable absorbent consumer products involving flimsy structures and fluids interacting at high speed.

• Fluid Structure Interaction for Immersed Bodies

  Jason Wang, Hao Chen - Livermore Software Technology Corporation

  A new method for automatically constructing the coupling surface along shell edges is developed. By using this new "edge" option together with "shell thickness" option in the *CONSTRAINED_LAGRANGE_IN_SOLID card, we can accurately model problems involving shell structures with leading edges cutting into ALE materials. Engineering problems include bird striking at propulsion system fan blades; helicopter impacting water. This new feature is implemented in the latest LS-DYNA 971 release 7600 and ready to use with minor input deck modifications. Before, in order to correctly model the FSI, blades had to be meshed by using Lagrange solid elements. This approach can ensure an accurate coupling interface but the time step size is greatly reduced due small element sizes. The lengthy running time for the problem makes this approach impractical. The new "edge" and "thickness" feature will construct a proper coupling surface from shell elements and provide reasonable time step sizes for the simulations.

• Fluid-Composite Structure-Interaction in Underwater Shock Simulations

  B. Özarmut, A. Rühl, B. Hennings, O. Nommensen, A. Paul (thyssenkrupp Marine Systems)

  Fiber reinforced plastics (FRP) and sandwich components are widely made use of in today’s submarines owing to their advantages such as high strength-to-weight ratio and durability in marine environment over conventional submarine building materials. Fig. 1 shows a state-of-the-art conventional submarine with an upper deck consisting of mostly composite components.

• Fluid-Structure Interaction Simulations of Mechanical Heart Valves with LS-DYNA ICFD

  Mariachiara Arminio, Dario Carbonaro, Sara Zambon, Rodrigo Paz, Facundo Del Pin, Umberto Morbiducci, Diego Gallo, Claudio Chiastra

  The aortic valve is responsible for allowing blood flow from the heart left ventricle into the aorta during the systolic phase of the cardiac cycle and for preventing backflow during the diastolic phase. The aortic valve is composed of three leaflets attached to the aortic root in proximity of three aortic dilations named sinuses of Valsalva. Leaflets open and close as a result of transvalvular pressure drop. Specifically, when the ventricular pressure is higher than the aortic pressure the leaflets open, whilst they close the valve orifice when the aortic pressure is higher than the ventricular pressure. Valve functionality may be impaired due to several conditions, such as aortic valve stenosis and aortic valve regurgitation, with a consequent increase in the risk of left ventricle hypertrophy and cardiac failure [1]. Among treatment options for aortic valve disease, a major role is played by the surgical replacement of the native valve with a prosthetic device.

• Fluid-Structure Interaction involving Close-in Detonation Effects on Column using LBE MM-ALE Method

  Swee Hong Tan, Shih Kwang Tay, Jiing Koon Poon, David Chng (ministry Of Home Affairs, Singapore)

  This paper shares the experiences gathered from studies conducted on the use of *Load_Blast_Enhanced (LBE) keyword to couple empirical blast loads to air domain in Multi-Material Arbitrary Lagrangian-Euler (MM-ALE) environment and on Fluid-Structure Interaction (FSI) computations relating to various aspects of coupling technique in LS-DYNA® via *Constrained_Lagrange_in_Solid keyword for structures composing of mainly solid elements. This paper also presents a case-study in which results from the LBE MM-ALE FSI simulation were compared to experimental data from full-scale blast trials, as well as results from associated pre-test simulations. The pre- test simulations were done using a 2-stage numerical approach which involved applying segmental pressure loadings derived from Computational Fluid Dynamics (CFD) calculations on LS-DYNA Lagrangian models to predict structural response.

• Fluid-Structure Interaction in LS-DYNA: Industrial Applications

  M’hamed Souli - Universite des Sciences et Technologie de Lille, Lars Olovson - LSTC

  Numerical problems due to element distortions limit the applicability of a Lagrangian description of motion when modeling large deformation processes. An alternative technique is the multi-material Eulerian formulation. It is a method where the material flows through a mesh that is completely fixed in space and where each element is allowed to contain a mixture of different materials. The method completely avoids element distortions and it can, through a Eulerian-Lagrangian coupling algorithm, be combined with a Lagrangian description of motion for parts of the model, see [3] and [4] The Eulerian formulation is not free from numerical problems. There are dissipation and dispersion problems associated with the flux of mass between elements. In addition, many elements might be needed for the Eulerian mesh to enclose the whole space where the material will be located during the simulated event. This is where the multi-material Arbitrary Lagrangian-Eulerian (ALE) formulation has its advantages. By translating, rotating and deforming the multi-material mesh in a controlled way, the mass flux between elements can be minimized and the mesh size can be kept smaller than in an Eulerian model.

• Fluid-Structure-Interaction Effects in Airbag Out-of- Position Load Cases: An introduction to the ALE- framework in LS-DYNA

  Dr. A. Haufe, Dr. K. Weimar - DYNAmore GmbH

• Following Nature’s Lead for Ultimate Design Efficiency The ACP Process as Applied to FSV

  Akbar Farahani (ETA Inc.), Jody Shaw (U.S. Steel)

  The shapes and configurations of nature are wildly complicated, non-intuitive and completely amazing. The shapes and forms found in nature in the structure of a tree, a human skeleton, insects and animals are truly the most efficient designs imaginable. By mimicking the flawless balance between structure and strength of nature’s most efficient shapes, engineers can learn how to incorporate similar balance to product structural design for automobiles, aircraft and other systems. The Accelerated Concept to Product (ACP) ProcessTM is a methodology which enables the structure of a product, such as the vehicle’s body-in-white, to mimic “Nature’s Way” [13]. Doing so creates the ultimate design efficiency, where structure and strength are perfectly balanced for the intended function. ACP is a proprietary, performance-driven, holistic product design development method based on design optimization and incorporates the use of multiple CAE tools in a systematic process to generate the optimal design solution. This methodology provides solutions, which address the challenges facing the modern product development environment. It achieves this by synchronizing the individual facets of the product development process, resulting in an overall reduction in development costs and time to market.

• Forging and Extrusion Analysis with LS-DYNA® using 3D Adaptive EFG Method

  Hongsheng Lu, C. T. Wu, Jingxiao Xu - Livermore Software Technology Corporation

  With the recent improvements in adaptive procedure, adaptive mesh-free method has become an important tool to solve the 3D forging and extrusion problems that usually involve large topology change with severe local deformation. In this paper, the implicit version of 3D adaptive EFG method with emphases on the state variable transfer between successive discretizations is presented, and several problems are used to illustrate the effectiveness of the proposed approach. A massively parallel processing (MPP) of adaptive EFG is implemented for the 3-D analysis, and the scalability test is conducted on the highly deformable inelastic example problems.

• Formability Modeling with LS-DYNA

  Torodd Berstad, Odd-Geir Lademo, Ketill O. Pedersen - SINTEF Materials and Chemistry, Odd S. Hopperstad - Norwegian University of Science and Technology

  This paper presents how the process of loss of stability, as described by the classical theory of Marciniak and Kuczynski, can be represented in non-linear finite element analyses with LS-DYNA. As will be seen, this is strongly dependent upon proper constitutive equations and parameters for the sheet material at hand. Of this reason two user-defined sub-routines for weakly and strongly textured aluminum alloys, respectively, have been implemented. Further, a non-local instability criterion has been implemented in order to detect incipient plastic instability. Next, some inhomogeneity must be introduced in the finite element model. In further analogy to the work of Marciniak and Kuczynski the inhomogeneity can be introduced either to the material properties or to the thickness. In order to perform the calculations in an efficient way, an automated procedure – called an FLD-calculator – has been created. Finally, the FEM-based calculations are compared with analytical and experimental results.

• Forming and spring-back simulation of CF-PEEK tape preforms

  S. Cassola, M. Duhovic, L. Münch, D. Schommer, J. Weber, J. Schlimbach, J. Hausmann (TU Kaiserslautern)

  The strive for high energy efficiency through lightweight design, especially for medium- and long haul aircrafts, has significantly increased the use of carbon fiber-reinforced plastics (CFRP) in the aviation industry in recent years [1]. High specific strength, corrosion resistance and improved fatigue life are only a few advantages that qualify CFRPs as structural parts in aircrafts. However, high material, manufacturing and assembly costs are still restricting their use [2]. Highly automated manufacturing processes, which provide a high degree of mounting part integration are needed to lower the part and assembly costs. Structural frames in aircraft fuselages currently make use of a differential design and consist either of aluminum, which provides insufficient specific strength or carbon fiber-reinforced thermosets, which involve long processing times. To overcome these drawbacks, a carbon fiber-reinforced, thermoplastic frame with integrated mounting parts has been developed in order to reduce the complexity of the assembly process. The frame is manufactured in an one-shot process involving tape preform production by automated tape laying (ATL) and a subsequent thermoforming step. ATL allows near-net-shape manufacturing of preforms, which reduces scrap rates to a minimum [3]. The subsequent thermoforming step enables the production of complex 3D-parts with low cycle time [4].

• Forming limit diagrams with an FE-based approach for sheets under non-proportional loading

  A. Reyes, O. S. Hopperstad - Norwegian University of Science and Technology, T. Berstad, O.-G. Lademo - Norwegian University of Science and Technology/ SINTEF Materials and Chemistry

  In this study, LS-DYNA was used to predict the experimental forming limit diagrams (FLDs) for pre- strained sheets in aluminum alloy Al2008-T4 found by Graf and Hosford [1]. The original data of Graf and Hosford [1] includes numerous pre-straining situations, but it was here chosen only to investigate pre-straining by biaxial and uniaxial tension. In order to generate the FLDs, several analyses of a square patch were run systematically to construct the different points. Pre-straining was applied by first stretching a somewhat larger patch to a given pre-strain, and then trimming this patch to the standard square patch. The material model used in the analyses includes two instability criteria; a non- local criterion to detect incipient localized necking and a through-thickness shear instability criterion [2-5]. The objective was to study whether the effects of pre-straining on the FLD could be predicted by the chosen modelling approach, and good results were obtained.

• Forming limit diagrams with an FE-based approach for sheets under non-proportional loading

  A. Reyes, O. S. Hopperstad - Norwegian University of Science and Technology, T. Berstad, O.-G. Lademo - Norwegian University of Science and Technology/ SINTEF Materials and Chemistry

  In this study, LS-DYNA was used to predict the experimental forming limit diagrams (FLDs) for pre- strained sheets in aluminum alloy Al2008-T4 found by Graf and Hosford [1]. The original data of Graf and Hosford [1] includes numerous pre-straining situations, but it was here chosen only to investigate pre-straining by biaxial and uniaxial tension. In order to generate the FLDs, several analyses of a square patch were run systematically to construct the different points. Pre-straining was applied by first stretching a somewhat larger patch to a given pre-strain, and then trimming this patch to the standard square patch. The material model used in the analyses includes two instability criteria; a non- local criterion to detect incipient localized necking and a through-thickness shear instability criterion [2-5]. The objective was to study whether the effects of pre-straining on the FLD could be predicted by the chosen modelling approach, and good results were obtained.

• Forming of alloy plate by underwater shock wave of explosive

  K. Kuroda, H. Hamada, H. Hamashima, S. Itoh - Kumamoto University, Japan

  The fuel cost and efficiency of the automobile greatly depend on the weight. Researches for light weight automotive components are actively being performed, and automobiles using Aluminium alloys instead of steel are becoming more common. However, Al alloys have limited formability in comparison with steel and its final shape is more limited. We have attempted to improve this limited formability of Al alloys by explosive forming technique, which is a particular material processing method. In this method, a shock wave is generated by an explosive and propagated through a suitable pressure medium, e.g. water or air, and deforms a metal plate. We performed numerical analysis using LS-DYNA3D, and compared the results to the experimental observations.

• Forming of Ultra-High-Strength Sheet Metals with Alternating Blank Draw-In

  R. Radonjic, M. Liewald (Universität Stuttgart)

  Reduction of the vehicle weight and improvement of the passenger safety are permanently defined requirements for design and manufacturing of the dedicated car body components. One possibility to fulfil before mentioned requirements is use of thin walled ultra-high-strength steel sheets for manufacturing of the car body structural parts. However, when forming such kind of sheet metal materials, severe problems may result from the large amount of springback, which occurs after release of formed part. In order to reduce part shape deviations from nominal, forming of a hat channel shaped part geometry with the alternating blank draw-in was modelled and simulated in this study. In this investigation an ultra-high-strength steel of DP 980 grade was used. Performed simulations were calculated by using the FE-Code LS-Dyna. In order to detect advantages of this kind of forming process, conventional deep drawing of the same part geometry was simulated as well. Simulation results showed that the part shape deviations after forming with the alternating blank draw-in were significantly reduced when comparing to part shape deviations occurring after conventional deep drawing with this symmetrical flange draw-in. Evaluation of simulation results before and after release of the part was carried out along three different cross sections to understand influence of complex stress state on springback occurrence of component. Finally, the successful process management which delivers negligible part shape deviations is presented in this paper.

• Forming Simulation for Fiber Reinforced Thermoplastic with Introduction to J-Composites

  Masato Nishi, Sean Wang, Shaun Dougherty, JSOL Corporation, Harumi Center Bldg. 2-5-24 Harumi, Chuo-ku, Tokyo, 104-0053, Japan

  Fiber reinforced composites are good alternatives for metals used in load transmission structures. The increasing requirement for high performance and weight reduction in industry has gradually expanded the use of composites. Finite element analysis as an alternative approach to experimental study is effective in designing fiber reinforced composite products because there are many design parameters. Process/process-chain simulations are especially important because the performance of the final composite part strongly depends on changes in fiber orientation during the process. In this context, we are developing the J-Composites series. A series of new software tools to help our LS-DYNA® users easily conduct process/process-chain simulations of fiber reinforced composites.

• Forming Simulation of Tailored Press Hardened Parts

  M. Triebus, A. Reitz, O. Grydin (Paderborn University), J. Grenz, A. Schneidt, R. Erhardt (BENTELER), T. Tröster, M. Schaper (Paderborn University)

  Hot forming of metal parts is characterized by forming over recrystallisation temperature [1]. For steel, press hardening is a popular production technology for creating hardened parts under hot forming conditions. In the conventional press hardening process, the blank is heated above austenitizing temperature and then transferred to the forming tool. The tools are water cooled and therefore ensure a martensitic transformation of the steel material. The most popular alloy is the boron steel 22MnB5, where a tensile strength of around 1500 MPa is reached through press hardening processes. The latest body-in-white concepts show a broad range of press hardened parts. The underlying forming methods are aiming to create purpose build components through variations of the press hardening process like tailored property processes, the use of tailor-welded or tailor-rolled blanks [2]. In the tailored property process, tailoring of the material properties is realized through the decrease of the cooling rate in a designated area of the part e.g., with a heated tool region. Due to the lower cooling rate, a softer and more ductile state is created in this area with microstructures of ferrite, pearlite and bainite. As a result, from the multiphase microstructure of tailored property parts, shape distortion is more pronounced then in conventional press hardening parts with a fully martensitic microstructure. Increased shape distortion can lead to additional rework cycles in the tool manufacturing.

• Forming Simulation of Textile Composites Using LS-DYNA

  M. Nishi, T. Hirashima (JSOL)

  The primary focus of this paper is on FE modeling and simulations performed to capture the material behaviors during a textile preform and a thermoplastic pre-preg forming manufacturing using LS-DYNA. Although an out-of-plane bending stiffness of textile reinforcement is often ignored as it is very low compared to in-plane stiffness, more accurate simulation, especially prediction of wrinkles, is achievable by considering out-of-plane bending stiffness in forming simulation. We propose a hybrid model which consists of a membrane and shells that can describe out-of-plane bending stiffness which is independent from in-plane behavior. In order to extend the textile reinforcement model to a thermoplastic pre-preg model for thermoforming simulation, temperature dependent stress contribution of thermoplastic is added to the textile reinforcement by applying Reuss model which can take the volume fraction of fiber into account.

• Forming Simulation, Meta Language and Input Decks

  M. Fleischer, J. Sarvas, H. Grass, J. Meinhardt (BMW Group)

  The use of finite element (FE) simulations for a virtual validation of the forming process for sheet metal parts has been introduced in the mid 1990s and is state of the art in the automotive industry today. Two challenging tasks for determining whether a tool design and its process parameters are feasible are the prediction of the material behavior during the forming process and the springback of the final part. For improving the predictive accuracy of the forming simulation, the level of detail has increased steadily regarding many aspects of the simulation model. For example, the material behavior during drawing is influenced by the preceding trimming operation as the latter causes damage at the trimmed edge. Furthermore, during the drawing the pressure distribution between the blank and the blankholder may vary significantly due to the deflection of the tool and the press. This can result in a disadvantageous restraining behavior. Considering these effects may lead to a further improvement of the simulation’s accuracy. As a result, the increase in size and level of detail of the FE models poses a challenge for the future simulation systems and their application. One way to deal with this complexity is a process orientation in the software workflows. The goal is to use of the best suitable program for each step in the simulation system. Therefore in the first step, pre-processor, solver and post-processor should be independent from each other. Therefore a neutral interface between the pre-processor and solver was generated with the meta language “OFPL”. With this meta language it is possible to describe metal forming processes in a process- and object-oriented way with a minimum of numeric parameters. Now, the next step is to model the solver input decks with object- and process-orientation.

• Forming simulations based on parameters obtained in microstructural cold rolling simulations in comparison to conventional forming simulations

  Sebastian Lossau - Daimler AG, Bob Svendsen - TU-Dortmund

  This work demonstrates a first approach of using virtually obtained material properties as input for forming simulations. The necessary parameters to apply a Barlat-Lian89 yield surface are computed in the so called “Virtual Lab”, which performs FE-simulations on previously cold rolled volume elements to predict the distribution of grains. The resultant stress-strain-curves serve as input parameter for a deep drawing simulation. For reference, an ordinary material data file determined by real uniaxial tension tests is compared to the virtual based material data file. Further, the results of both simulations are exhibited to allow a first evaluation of the deviation from each other. In particular, the Lankford Parameters in 0° and 90° with respect to the rolling direction are predicted by the Virtual Lab quite well. Only the 45° value requires improvement for future analysis of material properties. Likewise, the extrapolation of the hardening curve shows a strong deviation at larger deformation. The equivalent plastic strain as well as the thickness reduction is less affected by this problem. However, the calculation of the equivalent stress is influenced strongly by the deviating hardening curves at larger strains. This expresses itself in an overestimation of the stress in the simulation as based on the virtually obtained properties.

• Forming simulations based on parameters obtained in microstructural cold rolling simulations in comparison to conventional forming simulations

  Sebastian Lossau - Daimler AG, Bob Svendsen - TU-Dortmund

  This work demonstrates a first approach of using virtually obtained material properties as input for forming simulations. The necessary parameters to apply a Barlat-Lian89 yield surface are computed in the so called “Virtual Lab”, which performs FE-simulations on previously cold rolled volume elements to predict the distribution of grains. The resultant stress-strain-curves serve as input parameter for a deep drawing simulation. For reference, an ordinary material data file determined by real uniaxial tension tests is compared to the virtual based material data file. Further, the results of both simulations are exhibited to allow a first evaluation of the deviation from each other. In particular, the Lankford Parameters in 0° and 90° with respect to the rolling direction are predicted by the Virtual Lab quite well. Only the 45° value requires improvement for future analysis of material properties. Likewise, the extrapolation of the hardening curve shows a strong deviation at larger deformation. The equivalent plastic strain as well as the thickness reduction is less affected by this problem. However, the calculation of the equivalent stress is influenced strongly by the deviating hardening curves at larger strains. This expresses itself in an overestimation of the stress in the simulation as based on the virtually obtained properties.

• Forming Simulations of Niobium Sheets - Upgrade of the Numerical Model and Outcome for Novel Productions

  A. Amorim Carvalho, M Garlaschè, A. Dallocchio, O. Capitana, L. Prever-Lori, M. Marduzzi, J. Brachet, B. Bulat (CERN); L. Peroni, M. Scapin (Politecnico di Torino)

  The installation of superconducting Radio Frequency (RF) Crab Cavities is one of the key upgrades in the framework of the High Luminosity Large Hadron Collider (HL-LHC) at CERN. These devices – built out of niobium sheets – are shaped into a complex geometry entailing very tight tolerances, in order to comply with strict RF requirements. Numerical simulations via LS-DYNA proved to be a useful tool to optimize the fabrication process of these RF cavities. Simulations are performed for predicting the capability of different processes and tools to yield shaped parts complying with geometry and surface requirements. Having gained experience from the production of a first crab cavity design, the numerical model was enhanced with implementation of material models stemming from a comprehensive testing campaign of niobium rolled sheets. The frame of upgraded simulations is currently contributing to the production campaign for the second crab cavity design, currently being carried out at CERN. This contribution will present the procedures followed for the upgrade of the numerical model and present the obtained results.

• Fracture Prediction and Correlation of AlSi Hot Stamped Steels with Different Models in LS-DYNA®

  G. Huang, H. Zhu, S. Sriram (ArcelorMittal Global R&D E. Chicago Center), Y. Chen, Z. C. Xia, O. Faruque (Ford Motor Company)

  Reliable predictions of the fracture behavior in a crash event have become ever important in recent years as they will enable the reduction of physical prototype testing and the acceleration of vehicle development time while maintaining high safety standards. The increasing use of even stronger grades of Advanced High-Strength Steels (AHSS) such as hot-stamped boron steels provides particular challenges to fracture modeling due to their microstructures and processing conditions. This paper provides a brief description of the different fracture criteria and their implementation currently available in LS-DYNA to model ductile failure. The focus is the determination of parameters for selected fracture criteria for AlSi coated press -hardenable steels using calibration tests at the coupon level and supported by FEA simulations.

• Fracture Prediction of High Strength Steels with Ductile Fracture Criterion and Strain Dependent Model of Anisotropy

  Kenji Takada (Honda R&D Co.)

  Cockcroft-Latham fracture criterion was applied to predict the fracture of high strength steels. Marciniak-type biaxial stretching tests of the four grades of high strength steels were carried out to measure the material constant of Cockcroft-Latham fracture criterion. Furthermore, in order to improve the simulation accuracy, the local anisotropic parameters depending on the plastic strain (strain dependent model of anisotropy) were measured by Digital Image Reconstruction system and incorporated into Hill's anisotropic yield condition by authors. To confirm the validity of Cockcroft-Latham fracture criterion, the uniaxial tensile tests based on JIS No.5 tensile specimen were performed. The force-displacement history and fracture happening strokes were predicted with high accuracy. Then, Cockcroft- Latham fracture criterion was applied to predict the failure of four types of spot welded joints. To simulate the local bending and warping deformations around the heat-affected zone, the discrete Kirchhoff triangle element was adapted. FEM results for four grades of high strength steels and four types of spot welded joints had good correlation with experimental ones.

• Free Fall Movement Decomposition of a Payload Released by Aircraft: Study of the Aerodynamic Coefficients Using the LS-DYNA ICFD Solver

  E. Grippon, M. Seulin, V. Lapoujade, T. Maillot, C. Michel (DynaS+)

  Through its multiphysics aspect, the airdrop domain is chosen to demonstrate the new FSI capacities recently developed within the LS-DYNA software (more specifically using the ICFD solver). To do this, DynaS+, French, Spanish and Portuguese distributor of LS-DYNA and associated services got a research and innovative subvention from the French Government, RAPID financing. The main goal of this project, PARAFLU, is to succeed in modeling the complete sequence of an airdrop, which includes three main phases: i. the payload freefall, ii. the deployment of the hemispherical parachute, iii. and the gliding phase when the payload is supported by the parachute sail. Each step includes aerodynamic and fluid-structure interactions problems more or less complex. This paper focuses on the payload freefall phase modelling. The falling movement of the payload released by the aircraft has been decomposed into simple motions. The package undergoes translation, rotation and combination of both, for Reynolds number ranging from 104 to 106. Similar cases from the literature have been reproduced in order to validate the ICFD solver capabilities. The aim is to evaluate its accuracy in reproducing aerodynamic phenomena such as the the aeronautical coefficients observed in these configurations. Particular attention has been paid in order to optimize the associated calculation times. Different models of turbulence have been studied.

• Free-Form Shape Optimization on CAD Models

  D.Baumgärtner, M. Breitenberger, K.-U. Bletzinger (TU München)

  A novel approach for the free-form shape optimization on CAD models is presented. The optimization workflow consists of three steps: - Creating a finite element mesh of the CAD model - Vertex-morphing for exploring the best design (Millions of DOFs possible) - Isogeometric B-Rep mapping for updating the CAD model The output of the proposed optimization workflow is a complete high-quality CAD model. The presented techniques allow controlling selectively geometric continuities (up to G²) on the edges of the mechanical optimized CAD model. Various examples from automotive and aircraft industry confirm the quality, flexibility, and robustness of the proposed optimization workflow and thus highlight the advantages of integrating vertex morphing and CAD modeling.

• Frequency Domain Analysis for Isogeometric Element in LS-DYNA ®

  Liping Li, Yun Huang, Zhe Cui (LSTC), Stefan Hartmann (DYNAmore GmbH), David J. Benson (Professor for Structural Engineering)

  In the past few years numerous researches have been done in the area of Isogeometric Analysis (IGA), as the simulation model is exactly the desired geometry in this method. Frequency domain analysis is a cheap and fast alternative for time domain analysis. It is particularly suitable for vibration and acoustic analysis, which are very important topics for the design and research of automotives. This paper gives some frequency domain analysis for isogeometric elements, and the results are compared with the finite element analysis (FEA) results.

• Friction in LS-DYNA®: Experimental Characterization and Modeling Application

  Sheng Dong, Marcelo Dapino (The Ohio State University), Allen Sheldon, Kishore Pydimarry (Honda R&D Americas, Inc.)

  Friction is a widely observed phenomenon in all engineering systems. The importance of friction in computer-aided engineering has long been overlooked and modeling of friction phenomenon has been oversimplified. This paper reports experimental work conducted on a pin-on-disc tribometer to characterize the coefficients of friction between various material combinations, and modeling work of using such measured coefficients in different CAE models. Tested material combinations include coated steel on coated steel and rubber on coated steel. The coefficients were measured under different normal stresses and linear velocities, and employed to a three- point bending model and a pedestrian collision model in CAE tools such as LS-DYNA. It was found that friction plays an important role in deciding the magnitudes and timing of the acceleration or force when initial collision takes place. Higher friction results in higher magnitude of acceleration and force, but shorter sliding distance after the initial collision. Parametric study adopts different values for the coefficient of friction, and the results show that there exist boundaries, within which the role of friction is more evident. Below the lower boundary value, the effect of friction was dwarfed by other factors. Above the upper boundary value, the effect of friction saturates. This methodology of measuring and applying friction coefficients can be applied to various CAE models beyond pedestrian-vehicle collision to assist finding better correlation between simulations and testing data.

• From 6 months to 6 weeks "Multi Disciplinary Optimisation MDO"

  Dr Tayeb Zeguer - Jaguar Landrover

  The traditional new-vehicle design cycle is very time consuming due to the sequential approach used. The need to reduce time to market for new vehicles as well as the increased affordability of high- performance computing, which can process hundreds of simulations concurrently, has led to the increased adoption of MDO processes. The goal of an MDO is to provide a more consistent, formalized process for complex system design than that found in traditional approaches, as well as to impact the design cycle through timely, performance-based direction. In essence, MDO aids in the management of the design process workflow itself. The MDO principle allows engineers and analysts to address multiple vehicle attributes such as safety performance, refinement and failure modes e.g. full frontal, offset, side and rear impacts, occupant restraints and total vehicle level NVH. This paper provides a formal and structured approach in the use of MDO at JaguarLandover to address complex and often conflicting requirements; arriving at better quality designs in a faster and more cost- effective manner. The use of MDO solutions increases the efficiency of the simulation processes by the following: Automation of many manual simulation processes to save time. Linking multiple simulation such as Crash, NVH and restrain to perform trade-off analyses Minimizing vehicle weight and meeting all vehicles attribute requirements. Find optimal designs and develop better products

• From 6 months to 6 weeks "Multi Disciplinary Optimisation MDO"

  Dr Tayeb Zeguer - Jaguar Landrover

  The traditional new-vehicle design cycle is very time consuming due to the sequential approach used. The need to reduce time to market for new vehicles as well as the increased affordability of high- performance computing, which can process hundreds of simulations concurrently, has led to the increased adoption of MDO processes. The goal of an MDO is to provide a more consistent, formalized process for complex system design than that found in traditional approaches, as well as to impact the design cycle through timely, performance-based direction. In essence, MDO aids in the management of the design process workflow itself. The MDO principle allows engineers and analysts to address multiple vehicle attributes such as safety performance, refinement and failure modes e.g. full frontal, offset, side and rear impacts, occupant restraints and total vehicle level NVH. This paper provides a formal and structured approach in the use of MDO at JaguarLandover to address complex and often conflicting requirements; arriving at better quality designs in a faster and more cost- effective manner. The use of MDO solutions increases the efficiency of the simulation processes by the following: Automation of many manual simulation processes to save time. Linking multiple simulation such as Crash, NVH and restrain to perform trade-off analyses Minimizing vehicle weight and meeting all vehicles attribute requirements. Find optimal designs and develop better products

• From automatic event detection to automatic cause correlation

  Nouran Abdelhady, Dominik Borsotto, Vinay Krishnappa, Clemens-August Thole

  Reaching and fulfilling several design and crash criteria during the development process is what makes the engineer adapt and redesign the simulation model over and over again. Ideally resulting in new simulation runs with in best case improved performance, matching the intention of the applied changes. For the more demanding case of unforeseen results which do not necessarily fit to the expectations of the actual changes, methods and a workflow are being introduced here, which allow to identify the root cause of this behavior.

• From automatic event detection to automatic cause correlation

  Nouran Abdelhady, Dominik Borsotto, Vinay Krishnappa

  Reaching and fulfilling several design and crash criteria during the development process is what makes the engineer adapt and redesign the simulation model over and over again. Ideally resulting in new simulation runs with in best case improved performance, matching the intention of the applied changes. For the more demanding case of unforeseen results which do not necessarily fit to the expectations of the actual changes, methods and a workflow are being introduced here, which allow to identify the root cause of this behavior.

• From Time Delayed MRI to Patient-specific computational modeling of scar-related ventricular Tachycardia

  K. El Houari, P. L’Eplattenier, C. Shao, I. Caldichoury, M. Rochette (Ansys/LST)

  Sudden cardiac death commonly occurs due to heart rhythm disorders called arrhythmia. Although recognized as the most efficient treatment options, Cardioverter Defibrillator implantation and tissue ablation are still not used to their full potential. Recently, advances in computational modeling and the increasing use of imaging tools have proven that patients’ digital twins can play a role in addressing these limitations. This paper presents such an approach using the industrial software ADAS-3D and LS-DYNA. The workflow starts from Late Gadolinium Enhanced-Magnetic Resonance Imaging (LGE-MRI) data from a patient with structural heart disease. The left ventricle and fibrotic substrate were analyzed using ADAS-3D software, which enables to distinguish between tissue that is healthy, scarred, and intermediate, and to extract topological information. This segmentation and tissue classification are used to build, using LS-DYNA, a detailed electrophysiology model containing the relevant features for simulating arrythmia. Using LS-DYNA, this model is then used to simulate a normal heartbeat and a clinical pacing protocol for inducing arrhythmia.

• Front Bumper Crashworthiness Optimization

  Shokri El Houssini - Daan Engineering s.n.c

  During a vehicles frontal crash, passengers jeopardize high acceleration and energy opposite to the mass follow direction of their bodies. This fact causes high injury to the passengers’ whole body; head, neck, chest, and legs. We started thinking of reducing this deceleration effect on passengers during the crash. This is because succeeding in reducing mass deceleration effect on the passengers’ bodies will lead to save passengers form serious injuries. Increasing the length of the front bumper crash boxes was a method to improve the impact energy absorption. However, increasing the geometry (the length of the crash box) of the front bumper assembly will lead to an endless chain of structure subassembly changes. Our methodology works on combing different types of materials and design optimization to control the crash deceleration while maintaining the geometry of the front bumper . This methodology works on absorbing or discharging the energy of the impact before the energy being transmitted in full to the passenger. On other word, we protect the passengers from the excessive energy which is generated by the crash before it reaches them. By having the control over these variables, our vehicles become safer to insure the safety for everyone. This methodology has a high potential to be applied to improve the side impact crash worthiness as well.

• FSI Based on CESE Compressible Flow Solver with Detailed Finite Rate Chemistry

  Kyoungsu Im, Grant Cook, Jr., Zeng-Chan Zhang (Livermore Software Technology, an ANSYS Company)

  We have developed a new module of the modeling fluid structure interaction with the finite-rate chemistry in compressible CESE solver, which is based on the immersed boundary FSI method, and fully coupled with the LS-DYNA® structural FEM solver. In the CESE fluid structure interaction solver, we have two principal treatment methods, i.e., the immersed boundary method with a direct-forcing strategy and the moving mesh method. Although the moving mesh method is more accurate than the immersed boundary method, the latter is most efficient and robust when the problem involves large deformation such as a structure demolition by explosion. In the present report, we have demonstrated most practical fluid structure interaction problems by using the immersed boundary method with chemistry: i) shock-induced combustion in front of a spherical projectile moving at supersonic speed, ii) the blast relief wall simulation in methane and air mixture (CH4/Air), and iii) the fracture of the shell and solid structures by high explosive spots in an H2/O2 premixed environment. The results are validated with existing experimental data and descriptions of the keyword setup are provided in detail for users.

• FSI Capabilities for the CESE and Chemistry Solvers in LS-DYNA®

  Kyoung-Su Im, Zen-Chan Zhang, Grant Cook, Jr., Livermore Software Technology Corp.

  Recently, we have developed a new class in the area of compressible flow, gaseous explosion, and FSI for users to assist from the fundamental problems to very complex high level FSI problems by using CESE and Chemistry solvers in LS-DYNA. In this presentation, we will give a step-by-step explanation about the main goal of the class, overviews of the compressible and chemical kinetics theories,the current capabilities of solvers, and the comprehensive 10 exercise problems which consist of two parts: i) the first part covers the compressible flows, cavitation, FSI, and FSI with multi body dynamics problems, and the second part desisgined the basic concepts of chemical kinetics, closed adiabatic spatially homogeneous premixed reactors, the detonating flows, and the deformation and failures of sturctures in the nuclear containment by H2 explosions. Each exercise problem consists of the problem descriptions, modeling methods, illustrative step by step keyword construction through animation movies, program run and the post processing. It is strongly believed that upon completing the course, users can easily not only develop the keyword files of their own models, but also achieve enough knowledge for the compressible flows, gaseous explosion with the realistic chemistry and also fluid structure interaction problems.

• FSI Simulation of a Double-deck Bus Cornering under Crosswind Effects

  Castro, H. G, UTN FRRe, UNNE-IMIT, CONICET, Argentina;, Paz, R. R., Del Pin, F., Caldichoury, I., Huang, Ch-J., LSTC, Livermore, California, USA

  Every road vehicle under motion experiences forces and moments caused by different sources. One of these sources is the wind. Several investigations have dealt with the effects of wind over road vehicles. Nowadays, it’s a common practice to include also the dynamic characteristics of the vehicle. Particularly, high sided road vehicles (e.g., double-deck buses) are highly demanded and have its center of mass in a relatively high location, so in combination with moderate velocities may give rise to rollover instabilities. In this work, an unsteady aerodynamics simulation of a simplified double-deck bus under the influence of crosswinds is performed, including the cornering scenario. The results obtained using ICFD/FSI capabilities in LS-DYNA® solver are compared with a theoretical quasi-steady analysis. The effects of crosswinds on the bus aerodynamics when cornering are evidenced as a key concept in the estimation of its rollover stability.

• FSI simulations to study eye biomechanics during a Non Contact Tonometry

  Elena Redaelli, Begoña Calvo, José Felix Rodríguez Matas, Giulia Luraghi, Jorge Grasa

  Understanding the corneal mechanical properties has great importance in the study of corneal pathologies and the prediction of refractive surgery outcomes. Non-Contact Tonometry (NCT) is a non-invasive diagnostic tool intended to characterize the corneal tissue response in vivo by applying a defined air-pulse. The development of a strong FSI tool amenable to model the NCT, applied to different structural and anatomical configurations, provides the basis to find the biomechanical properties of the corneal tissue in vivo. This paper presents a high-fidelity finite-element model of a patient-specific 3D eye for in-silico NCT. A fluid-structure interaction (FSI) simulation is developed to virtually apply a defined air-pulse to a patient-specific eye model comprising cornea, limbus, sclera, and humors. Three different methodologies are tested to model the humors and the best approach is chosen. Then, a Montecarlo simulation is performed varying both the parameters describing the mechanical behaviour of the corneal tissue and the IOP. The analysis reveals that the mechanical properties of the corneal tissue and the IOP are perfectly coupled. A stiffer material with a low IOP can give the same deformation result on the cornea as a softer material with an higher IOP.

• FSI Simulations with LS-DYNA ICFD Solver: Capabilities, and Best Practices

  Satish Kumar Meenakshisundaram, Facundo Del Pin

  This document presents an overview of the LS-DYNA ICFD (Incompressible Computational Fluid Dynamics) solver and best practices for its efficient use in solving complex Fluid-Structure Interaction (FSI) problems from a user's perspective. LS-DYNA ICFD solver is a powerful tool for simulating the interaction between fluids and solid structures, allowing for accurate predictions of real-world phenomena. This paper will cover the underlying principles of the ICFD solver, its unique features, and practical applications, along with tips for efficient use. The content presented is crafted to ensure that engineers, regardless of their level of experience with FSI simulations, can easily understand and benefit from it. This document aims to provide a clear and concise guide for researchers and engineers who seek to utilize LS-DYNA ICFD solver for their FSI simulations, enabling them to achieve the expected throughput and save time in the process.

• FSI with the Detailed Chemistry and their Applications in LS-DYNA® CESE Compressible Solver

  I. Kyoung-Su, Z. Zhang, G. Cook (LSTC)

  Recently, we have developed a new module of the modeling fluid structure interaction with the finiterate chemistry in compressible CESE solver, which is based on the immersed bounday FSI method, and fully coupled with the LS-DYNA® structual FEM solver. In the CESE fluid structure interaction solver, we have two principal treatment methods, i.e., the immersed boundary method with a directforcing strategy and the moving mesh method. Although the moving mesh method is more accurate than the immersed boundary method, the latter is most efficient and robust when the problem involves large deformation such as a structure demolition by explosion. In the present report, we have demonstrated most practical fluid structure interaction problems by using the immersed boundary method with chemistry: i) shock-induced combustion in front of a spherical projectile moving at supersonic speed, ii) the blast refief wall simulation in methane and air mixture (CH4/Air), and iii) the fracture of the shell and solid structures by high explosive spots in an H2/O2 premixed environment. The results are validated with existing experimental data and descriptions of the keyword setup are provided in details for users.

• FTSS FEA Dummy Models update: SID-IIs Small Side Impact Dummy Model and others

  Fuchun Zhu, York Huang - First Technology Safety Systems, Inc.

  SID-IIs, the small side impact dummy, is the smallest side impact crash test dummy currently available in the market, representing the anthropometry of a small female or a thirteen-year-old child. It is designed specifically to evaluate the performance of advanced occupant protection systems, such as side air bags, in automotive side impact situations. This paper presents the development and validation of new FTSS SID-IIs dummy model for LS-Dyna solver. FTSS started the SID-IIs model development in early 2001, and accelerated the developing process in September due to the increasing demand for this crash test dummy in both physical and FEA versions. Now a fully validated SID-IIs FEA model is available in version 1.0. The SID-IIs model faithfully represents the physical dummy hardware from head to toe. It includes all the hardware components, accelerometers, load cells and linear potentiometers to measure rib deflections. Pro-Engineer CAD model was used in the model geometry creation. Nine common materials were used in the model, and their performance has been proved stable in the other FTSS dummy models. Totally the SID-IIs model consists of about 47,000 nodes and over 65,000 elements. The minimum time step has been controlled as 1.03 µs. Validation of the model has been done on various levels, which includes material and component tests, such as standard SID-IIs head drop test, lateral neck flexion test, Rib drop test, arm drop test, shoulder plug drop test and pelvis plug drop test, and full body calibration tests on different areas, such as shoulder, thorax, abdomen and pelvis. The model was finally validated against sled test data. The criteria for model validation accuracy were controlled at less than 10% off for component level, and 15% for full body dummy level. The model showed stable and robust performance with reasonable accuracy in prediction. Details about model development and validation will be presented in this paper. It is believed that the SID-IIs FEA model can serve as a useful tool in the early stage of vehicle design and safety simulation.

• Fujitsu-HPC-cluster-link-collection.pdf
• Full Cycle Simulation, Virtual Tryout and Reality Check

  Y. Hu, H. Hu, K. Li (Chrysler Group LLC)

  Full Process Simulation is the Simulation on all line dies (all nominal design dies) with formability results and final springback results at the end of the line. Full Cycle Simulation is the Simulation on all line dies (all compensated dies) with formability and springback results on panels from each operation. The final operation panel must meet the GD&T tolerance requirements. The final surface quality must meet the NC programming quality requirements. The operation panels must meet nesting/fitting tolerance requirements. This full process full cycle simulations presented tremendous challenges to Chrysler stamping simulation engineers. In Chrysler, we did full process full cycle simulation on all of our in house stamping line dies, hoping that we will achieve significant improvement in our stamping dimensional quality. The reality is a vailable now to be shared with the stamping simulation community. In this presentation, a typical full cycle simulation flow is included to show how the virtual tryout is iteratively performed to achieve dimensional accuracy. CMM data are collected after real tryout and summary of the CMM data is included to show the reality check. Room for improvement is obvious after reviewing the reality check.

• Full Electric Vehicle Crash Simulation Using Coupled Thermal-Electrical-Mechanical Analysis

  Chenxi Ling, Leyu Wang, Cing-Dao (Steve) Kan, Chi Yang

  The safety of electric vehicles (EVs) has become increasingly important as the number of EVs has grown rapidly in recent years. This work presents a system solution to model the full EV structural crash analysis together with its active battery cells using a thermal-mechanical-electrical coupled analysis. This multi-physics analysis predicts the sequence of events that could lead to thermal runaway and battery fire. In previous work, a representative battery cell model was first developed based on matching the cell dimensions and the total amount of material in a realistic cell. Each battery component was modeled separately with realistic mechanical, electrical, and thermal material models.

• Further Advances in Simulating the Processing of Composite Materials by Electromagnetic Induction

  M. Duhovic, M. Hümbert, P. Mitschang, M. Maier (Institut für Verbundwerkstoffe GmbH), P. L’Eplattenier , I. Çaldichoury (LSTC)

  Continuous induction welding is an advanced material processing method with a very high potential of providing a flexible, fast and energy efficient means of joining together thermoplastic composites to themselves and metal alloys. However, optimization of the process is very difficult as it involves the interaction of up to four different types of physics. In the previous installments of this work, static plate heating and continuous induction welding simulations of carbon fiber reinforce thermoplastic (CFRTP) plates were presented looking in particular at point temperature measurements and 3D surface plots of the in-plane temperature distribution across the entire width of the joint on the top as well as the joining interface of the laminate stack. In this paper, static plate heating tests are once again revisited and the importance of through the thickness temperature behavior is considered. For a single plate, the through thickness temperature profile follows a predictable pattern when using an induction frequency producing a skin depth of the same thickness as the plate. For two stacked but unconnected plates, the temperature profile becomes less obvious, in particular for plate stacks of different thicknesses. By correctly simulating the through thickness temperature profile the heating behavior can be ultimately controlled via top surface air-jet cooling together with other induction equipment parameters giving an optimum heating effect at the joining interface. In addition, further developments in the induction heating electromagnetism module available in LS-DYNA® R7 are examined including the inclusion of an orthotropic electromagnetic material model as well as electrical contact and its resulting contact resistance and effect on the overall heating behavior

• Further Improvements to the Truck Model for Roadside Safety Simulation – Suspension and Steering

  Dustin A. Boesch - Quartus Engineering Inc., John D. Reid - University of Nebraska-Lincoln

  Pickup trucks are commonly used for crash testing of roadside safety hardware, while nonlinear finite element analysis using LS-DYNA is commonly used to simulate that crash testing. To improve the accuracy of simulation a new front suspension and steering system was developed to replace the existing system on a pickup truck model used for roadside safety simulation. All of the critical components, such as mounting points, alignment, track width and mass, were incorporated into the new model, along with the capability to make the most important components deformable by carefully modeling the geometric details. It is believed that these modifications significantly improve the performance of simulating impacts with roadside curbs, rocks, or culvert grates, where dynamic suspension movement is essential, and with guardrail systems when deformation of the lower control arm is important

• Further Validation of the Global Human Body Model Consortium 50th Percentile Male Pelvis Finite Element Model

  Daniel Grindle, Yunzhu Meng, Costin Untaroiu (Virginia Tech)

  Road traffic accidents are the eighth leading cause of death worldwide, killing 1.35 million annually. The Global Human Body Model Consortium (GHBMC) has previously created and validated a finite element model of a 50th percentile male pedestrian in LS-DYNA® to investigate vehicle-pedestrian impacts. To assure and improve the model’s biofidelity, additional model improvements were made to the GHBMC pelvis model. These pelvis developments included the addition of acetabular cartilage and the optimization of material properties. The updated pelvis model was calibrated against Post-Mortem Human Surrogate (PMHS) component tests: dynamic lateral acetabulum loading, dynamic lateral iliac wing loading, and quasi-static sacroiliac joint loading. After new material properties were established for the pelvis model, the updated properties were applied to the whole-body GHBMC model. The updated model pelvis injury response was validated against whole-body PMHS lateral vehicle impact tests. More biofidelic biomechanical responses were observed in the updated pelvis model in the majority of component level validations. In addition, the fracture patterns of the updated pelvis matched the PMHS fracture patterns in whole-body impacts. This updated pelvis model will be incorporated into the next generation of GHBMC models. In future, it can be used to properly investigate pelvis injury mechanisms in impact scenarios to reduce pedestrian injuries in traffic accidents.

• Gas Dynamic Simulation of Curtain Airbag Deployment through Interior Trims

  Bill Feng, David Coleman - Jaguar Cars and Land Rover

  The curtain airbag is usually simulated by a uniform pressure method in which the pressure of the airbag is considered as constant. This is correct when the airbag is fully deployed. However, this assumption is not valid during the curtain airbag deployment phase, where the gas flow passing through each chamber can be clearly seen. Therefore it is impossible to simulate the intermediate sequences of the airbag deployment correctly by using the conventional uniform pressure method. The gas dynamic module has been made available within LS-DYNA®. This module provides the basic toolset to simulate gas flow. This technique enables us to simulate the gas flow and pressure distributions in detail and enables the correct sequences of the curtain airbag deployment. Interactions between the airbag and interior trims can now be simulated and well understood. This gas dynamic simulation method can be implemented to identify the potential failure modes of the curtain airbag during deployment through trims in the design development stage of the programme. Therefore, the confidence level for “right first time” curtain airbag deployment can be greatly increased.

• GasDynamic Simulation Capability for Side Impact Pressure Sensing Calibration

  Bill Feng, Amarjit Grewal (Body CAE, Jaguar Land Rover Ltd), Steve Hickman, Dave Moore, Alexandro Badea-Romero (Vehicle Safety, Jaguar Land Rover Ltd), Christian Dalton (Semcon Engineering)

  A method has been developed that uses crash simulation models to provide side impact door pressure sensor data to the sensor calibration engineers much earlier than was hitherto possible, thereby affording the opportunity to reduce the time period required for physical sensor calibration in the vehicle development programme.

• General Approach for Concrete Modeling: Impact on Reinforced Concrete

  N. Van Dorsselaer, V. Lapoujade (DynAS+), G. Nahas, F. Tarallo, J.-M. Rambach (Institut de Radioprotection et de Sûreté Nucléaire)

  In the world of Numerical Simulation, concrete modeling is one of the most complicated aspect engineers have to carry out. In fact, damage and failure occurring during concrete deformation are very complex processes difficult to reproduce with material models. And to make matters worse, material information available for concrete is often much reduced, leaving engineers profess structure performance without sufficient data. ®LS-DYNA has several material laws to model concrete behavior, and other modeling choices like hourglass treatment and boundary conditions are crucial. All these possibilities lead to a problem of “engineering dependence” for simulation results. This paper offers a general modeling approach for concrete modeling, where the main goal is to try to understand the ins and outs of different modeling to be able to have an overall view of a problem. This general modeling approach will be showed with the example of an impact on a reinforced concrete structure, setting up DoE study investigating material models, Boundary Conditions ®and Hourglass aspects, and using LS-OPT to perform Sensitivity Analysis and Optimizations assessing concrete behavior.

• General considerations for the influence of mesh density in LS Dyna

  Udo Jankowski, Manfed Sans, Michael Fairchild - TECOSIM GmbH

  Accurate and reliable CAE results are essential for the product development process in manufacturing industries. This is particularly so in the automotive industry where virtual simulation predictions are gradually replacing physical testing in the ever greater drive to reduce product development time and costs. CAE is nowadays completely integrated in the development process and critical design decisions are often based on the FEM calculations. The accuracy of predictions is very much dependent on the detail used to model physical structures; larger the models, better the results. However, larger models also demand much greater computing resources, especially for crash simulations. Model sizes are, therefore, dictated by reasonable computing times to solve the equations. At the same time, there is also a tendency to produce larger models not only for better accuracy but also as a result of use of automatic model generation to reduce time and cost for this phase of CAE analysis and to enable effective decision making based on CAE performance predictions. This background will be documented in this paper.

• Generalized Anistropic/Isotropic Porous Media Flows in LS-DYNA

  R. R. Paz, F. Del Pin, I. Caldichoury (LSTC), H. G. Castro (Conicet)

  In recent years industries like aerospace, automotive and those related to oil production have increased their trustfulness on numerical models and codes for the design, research, production and verification of highly critical parts and production processes. Most of these industries have adopted manufacturing procedures involving composites materials in liquid state, like the Liquid Composite Molding (LCM) and the High Pressure Resin Transfer Molding (HPRTM) methods, where a Newtonian (or Non- Newtonian) fluid flows through highly anistropic matrices filling an initially empty container.

• Generalized Porous Media Flow in ICFD-LS-DYNA: FSI, Free-Surface, RTM and Parachute Modeling

  R. Paz, F. Del Pin, I. Caldichoury (LSTC); H. Castro (Conicet)

  In recent years industries like aerospace, automotive and those related to oil production have increased their trustfulness on numerical models and codes for the design, research, production and verification of highly critical parts and production processes. Most of these industries have adopted manufacturing procedures involving composites materials in liquid state, like the Liquid Composite Molding (LCM) and the High Pressure Resin Transfer Molding (HPRTM) methods, where a Newtonian (or Non-Newtonian) fluid flows through highly anistropic matrices filling an initially empty container. Hydraulic fracture (or Fracking), where the rock containing the oil is fractured by a hydraulically pressurized liquid, is another example of problems where a free surface flow develops over a porous material. In this article the numerical modeling of the free-surface fluid flow through general anistropic porous media is introduced. Also, Fluid/Structure Interaction modeling involving the dynamics of a porous fabric (like parachute deployment) is presented. A generalization of the Navier-Stokes equations that will allow the definition of sub-domains with different permeability/porosity was developed. A level-set technique is used to track and correctly represent the moving interfaces in free-surface problems. The SUPG|OSS stabilizing Finite Element Method for the spatial approximation and the second-order Fractional Step Method for the time integration were adopted.

• Generating Experimental Data for a Three-Dimensional Generalized Composite Material Model

  Bilal Khaled, Nathan Holt, Loukham Shyamsunder, Canio Hoffarth and Subramaniam D. Rajan, School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ;, Robert K. Goldberg, NASA-GRC, Cleveland, OH;, Kelly S. Carney and Paul DuBois;, George Mason University, Fairfax, VA;, Gunther Blankenhorn,LSTC, Livermore, CA

  A three-dimensional orthotropic elasto-plastic composite material model is being implemented in a special version of LS-DYNA® as MAT213. The model is driven by experimental data that describe the elasto-plastic deformation behavior, coupled and uncoupled damage, and failure. This paper documents the test procedures to characterize the material behavior via tensile, compressive, shear and off-axis tests of as well as tests to generate validation data via stacked ply coupons. The theory and implementation of the algorithm are discussed in companion papers. A unidirectional composite, T800-F3900 fiber/resin composite material, commonly used in the aerospace industry is used to illustrate experimental procedures followed by the verification and validation processes.

• Geometry-Based Topology Optimization - Improving Head Impact Performance of an Engine Hood

  D. Weiss, B. Sonntag, T. Krumenaker, Dr. D. Nowottny, Dr. J. Sprave, W. Hipp - Daimler AG

  The actual paper introduces the integration of LS-DYNA and CATIA V5 into automatic geometry- based topology optimization of an engine hood regarding pedestrian head impact. In current design processes, such Computer Aided Engineering (CAE) tools, along with structural optimization, have become essential elements to provide efficient and reliable structures. However, the required iterative process of adjusting steps between simulation and design engineers is still a time-consuming task. In recent years therefore, automatic multi-criteria and multi-disciplinary optimization simultaneously considering different simulation disciplines have drawn increasing attention. For structure creation or topology variation, FE-based concepts have been developed working on a discretized design space, whereas geometry-based parameter variation on CAD models has been mainly used for shape and size variation. Although being a first step toward design process automation, both concepts are a trade-off between accuracy and creativity. The final goal would therefore be to combine the topology variation ability of the FE-based method with the ready-to-use solution of the parameter concept. Hence, extending the idea of parameter variation with the addition and removal of entire geometrical features, automatic topology variation on CAD structures is introduced. However, applying such geometry variation implies further considerations regarding a fully automated optimization loop such as accurate CAD build-up, update-stability, high quality batch meshing and a rapidly increasing number of free parameters. The project this work is based on aims at full automation of a geometry-based optimization loop for optimum structure generation using CATIA V5 and LS-DYNA. The concept is applied to pedestrian safety considerations, analyzing different engine hood topologies regarding their head impact performance. In a first step, parameter studies and simplified impactor load cases are run using the automatic CAD- FE loop as a pre-stage to a full multi-criteria optimization. The paper's focus is set on the concept's applicability to industrial processes. Hence, solutions regarding automated CAD-FE transition for evaluation are discussed as well as general limitations of CAD-based topology optimization. In particular the demanding task of batch meshing for varying topologies and sensitivity analyses to reduce the number of free parameters are addressed.

• Geometry-Based Topology Optimization - Improving Head Impact Performance of an Engine Hood

  D. Weiss, B. Sonntag, T. Krumenaker, Dr. D. Nowottny, Dr. J. Sprave, W. Hipp - Daimler AG

  The actual paper introduces the integration of LS-DYNA and CATIA V5 into automatic geometry- based topology optimization of an engine hood regarding pedestrian head impact. In current design processes, such Computer Aided Engineering (CAE) tools, along with structural optimization, have become essential elements to provide efficient and reliable structures. However, the required iterative process of adjusting steps between simulation and design engineers is still a time-consuming task. In recent years therefore, automatic multi-criteria and multi-disciplinary optimization simultaneously considering different simulation disciplines have drawn increasing attention. For structure creation or topology variation, FE-based concepts have been developed working on a discretized design space, whereas geometry-based parameter variation on CAD models has been mainly used for shape and size variation. Although being a first step toward design process automation, both concepts are a trade-off between accuracy and creativity. The final goal would therefore be to combine the topology variation ability of the FE-based method with the ready-to-use solution of the parameter concept. Hence, extending the idea of parameter variation with the addition and removal of entire geometrical features, automatic topology variation on CAD structures is introduced. However, applying such geometry variation implies further considerations regarding a fully automated optimization loop such as accurate CAD build-up, update-stability, high quality batch meshing and a rapidly increasing number of free parameters. The project this work is based on aims at full automation of a geometry-based optimization loop for optimum structure generation using CATIA V5 and LS-DYNA. The concept is applied to pedestrian safety considerations, analyzing different engine hood topologies regarding their head impact performance. In a first step, parameter studies and simplified impactor load cases are run using the automatic CAD- FE loop as a pre-stage to a full multi-criteria optimization. The paper's focus is set on the concept's applicability to industrial processes. Hence, solutions regarding automated CAD-FE transition for evaluation are discussed as well as general limitations of CAD-based topology optimization. In particular the demanding task of batch meshing for varying topologies and sensitivity analyses to reduce the number of free parameters are addressed.

• Getting Your Model ‘Right’ – Checking Before, During and After Your LS-DYNA® Analysis

  Gavin Newlands, Arup

  To be able to capture more and more detail in an analysis, LS-DYNA models continue to increase in size and complexity. A model can now commonly have ten to twenty million elements and it is essential that checking procedures are used to ensure that the model is ‘right’. As element count increases, checking a LS-DYNA model can be a difficult process as many of the checks can be very complex. Having robust methods for checking a keyword deck both interactively and as part of any automatic process is therefore essential for quality models and correct results. Ultimately this will also give significant time savings.

• GISSMO Based Material Characterization Using Workflows in d3VIEW

  Shashank Dhanakshirur, Apurva Walke (d3VIEW), Suri Bala (d3VIEW and Ansys/LST), Paul DuBois (Consultant)

  In times when the automotive industry is trying ways to reduce the R&D time for a new vehicle, material characterization using Workflows provide a structured way to develop a material card quickly and efficiently. GISSMO Material Development workflow greatly reduces the time required to generate and edit LS-DYNA® input files, visualize the results and automate decision-making aimed for optimization. The workflow is divided into sections as hardening curve optimization, Triaxiality curve optimization, mesh regularization, evaluation runs and result generation to make the challenging and complicate process of developing material model seem easy and user-friendly. Advantages of the workflow are timesaving, ease of use, efficient and flexible to adapt to the requirements of different materials.

• Global and Local Coupling Analysis for Small Components in Drop Simulation

  Jason Wu - Motorola

  The failure induced in radio/phone drop often associate with the damage of inside small components or its tiny substructures. The difficulty to detect the failure in drop simulation is: i) the right drop-induced shock at the components must come from the simulation at whole- phone model; ii) the required output at the small components needs very fine local mesh, which causes unbearable CPU cost and make the simulation impossible. Mass-scaling technique is unsuitable for the case. A global-and-local coupling method is presented in this paper to solve the problem. The method is demonstrated by an example of a connector (global model in coarse mesh) to search stresses of its solder joints (local model). The displacement and stresses calculated by the method are correlated to the results from a finely meshed model. The correlation verifies good agreement of calculated displacement in the two models, and small difference of stress prediction. The source of the error and possible improvement are analyzed in the paper.

• Global Sensitivity Analysis in Structural Optimization

  Uwe Reuter - TU Dresden, Martin Liebscher, Heiner Müllerschön - DYNAmore GmbH

  The main purpose of global sensitivity analysis is to identify the most significant model parameters affect- ing a specific model response. This helps engineers to improve the model understanding and provides valueable information to reduce the computational effort in structural optimization. A structural optimiza- tion is characterized by a set of design parameters, constraints and objective functions formulated on basis of model responses. The computational effort of a structural optimization depends besides the complexity of the computational model heavily on the number of design parameters. However in many cases an objective function is dominated only by a few design parameters. Results of global sensitivity analysis may be used to select the most significant design parameters from a number of potential can- didates and thereby reduce the optimization problem by the insignificant ones. In this paper different sensitivity measures and associated algorithms are evaluated with respect to their capabilities and com- putational costs. In particular the variance-based approach after Sobol is compared with the correlation analysis, the linear and quadratic ANOVA approaches, and the FAST approach. This is done using a comprehensible academic example as well as an optimization problem from engineering practice. Keywords:

• Global Sensitivity Analysis in Structural Optimization

  Uwe Reuter - TU Dresden, Martin Liebscher, Heiner Müllerschön - DYNAmore GmbH

  The main purpose of global sensitivity analysis is to identify the most significant model parameters affect- ing a specific model response. This helps engineers to improve the model understanding and provides valueable information to reduce the computational effort in structural optimization. A structural optimiza- tion is characterized by a set of design parameters, constraints and objective functions formulated on basis of model responses. The computational effort of a structural optimization depends besides the complexity of the computational model heavily on the number of design parameters. However in many cases an objective function is dominated only by a few design parameters. Results of global sensitivity analysis may be used to select the most significant design parameters from a number of potential can- didates and thereby reduce the optimization problem by the insignificant ones. In this paper different sensitivity measures and associated algorithms are evaluated with respect to their capabilities and com- putational costs. In particular the variance-based approach after Sobol is compared with the correlation analysis, the linear and quadratic ANOVA approaches, and the FAST approach. This is done using a comprehensible academic example as well as an optimization problem from engineering practice. Keywords:

• Golf Ball Impact: Material Characterization and Transient Simulation

  X. Liu, D. Quinn, J. Bergström (Veryst Engineering)

  ®This paper presents an LS-DYNA simulation of the impact event when a golf club hits a golf ball. This is a challenging subject for finite element simulations because it is characterized by high strain rate behavior: the impact occurs within milliseconds and the golf ball experiences very large deformation during this period because of the ball’s polymeric shell and core. The simulation strategy emphasizes on accurate material characterization and realistic model construction. Specifically, the Parallel Network Model (PNM), an advanced nonlinear viscoelastic and strain rate dependent material model from Veryst Engineering’s PolyUMod TM library is calibrated with high-rate testing data to accurately capture the highly nonlinear behavior of the golf ball core material during impact. At the same time, a detailed finite element model of the golf ball is constructed with multiple layers of structure. The complex dimple pattern on the ball cover as well as the grooves on the golf club are modeled, both potentially important factors in impact response. The simulation is validated by comparing the deformed shape at maximum impact to that in real experiments. The paper then discusses two important issues in material characterization: selection of the right material model and the availability of reliable high-rate testing data. The PNM material model is compared to a linear viscoelastic (LVE) model to demonstrate its superiority.

• GOM Company Overview.pdf
• Gradient enhanced damage: modelling, implementation and applications

  H. Schmidt (Bertrandt), Prof. A. Matzenmiller, M. Nahrmann (University of Kassel)

  Finite element (FE) simulations with constitutive models for softening materials, such as in the case of standard continuum damage mechanics based approaches, suffer from pathological mesh sensitivity as a result of strain localisation into a single element row. To overcome this major drawback, the local damage has to be enhanced towards nonlocal damage evolution. A suitable method for this purpose is the integral nonlocal formulation, available in LS-DYNA® by the keyword *MAT_NONLOCAL. However, its costly underlying search algorithm can result in a strong increase of the simulation time, leading to an impractical application for engineering problems.

• Grid-Based LS-DYNA Solutions

  Henry H. Fong, Jonas Edberg - Sun Microsystems, Inc.

  In addition to offering SPARC/Solaris systems for MCAE users, Sun Microsystems also markets Opteron-based servers and workstations. These Opteron solutions offer excellent price/performance for LS-DYNA simulations, and are particularly suitable for clustering. Users have a choice of three operating systems: Solaris 10 x64; Linux (SuSE or Red Hat); or Microsoft Windows. This paper describes briefly these computing systems, and show some typical LS-DYNA performances on standard benchmarks such the 3-car- crash problem. Also cited is a Mefos cold rolling benchmark, run using both a SPARC/Solaris Sun Fire V480 server as well as a cluster of Sun LX50 Xeon- based processors. Sun's cluster systems typically utilize Sun's N1GE grid engine load management software to schedule, manage, and prioritize compute jobs.

• Ground Vehicle Aerodynamics using LS-DYNA

  F. Del Pin, I. Caldichoury, R. R. Paz (LSTC)

  The use of software for the simulation of airflow around ground vehicles plays an important role in the design of a vehicle. Traditionally companies within the automotive industry sector have a Computational Fluid Dynamics department dedicated to the analysis of drag and lift with the objective of improving fuel efficiency, safety, passenger comfort, cooling systems and heat exchangers and minimizing noise. In recent years the increased pressure from government regulators for dramatic improvements in fuel efficiency has pushed the automotive industry to start innovating in lighter materials and hybrid or full electric cars.

• Grouping detection of uncertain structural process by means of cluster analysis

  Aleksandra Piotrow, Stephan Pannier, Wolfgang Graf - TU Dresden, Martin Liebscher - DYNAmore GmbH

  Structural analysis under consideration of the uncertainty of input parameters, such as loads, material, and geometry leads to uncertain time-dependent results. Such uncertain structural process shows for the uncertain input parameters all possible behaviours of a structure. Modelling of uncertainty in input parameters when only incomplete or expert knowledge based information is available requires the introduction of the uncertainty model fuzziness. A fuzzy process is a fuzzy set of real valued processes, whereas each of them possesses an assigned membership value indicating the degree of possibility. In order to obtain an engineering interpretation of a fuzzy process some representative crisp processes have to be chosen from numerous realisations of this uncertain function. In this paper a cluster analysis based approach for grouping similar and detecting different time-dependent structure behaviours is introduced. The similarity of processes within one cluster is assessed with similarity metrics: neighbouring location, affinity, and correlation. The uncertain assignment of real valued realizations of fuzzy process to clusters is executed with the Fuzzy-c-Means cluster algorithm. The capability of this approach is demonstrated within the controlled collapse simulation of a reinforced concrete framework structure carried out in LS-DYNA. In this example an analysis of a fuzzy process is performed by means of cluster methods and "-level discretization in order to select collapse sequences, significantly differing from each other and having other degrees of possibility.

• Grouping detection of uncertain structural process by means of cluster analysis

  Aleksandra Piotrow, Stephan Pannier, Wolfgang Graf - TU Dresden, Martin Liebscher - DYNAmore GmbH

  Structural analysis under consideration of the uncertainty of input parameters, such as loads, material, and geometry leads to uncertain time-dependent results. Such uncertain structural process shows for the uncertain input parameters all possible behaviours of a structure. Modelling of uncertainty in input parameters when only incomplete or expert knowledge based information is available requires the introduction of the uncertainty model fuzziness. A fuzzy process is a fuzzy set of real valued processes, whereas each of them possesses an assigned membership value indicating the degree of possibility. In order to obtain an engineering interpretation of a fuzzy process some representative crisp processes have to be chosen from numerous realisations of this uncertain function. In this paper a cluster analysis based approach for grouping similar and detecting different time-dependent structure behaviours is introduced. The similarity of processes within one cluster is assessed with similarity metrics: neighbouring location, affinity, and correlation. The uncertain assignment of real valued realizations of fuzzy process to clusters is executed with the Fuzzy-c-Means cluster algorithm. The capability of this approach is demonstrated within the controlled collapse simulation of a reinforced concrete framework structure carried out in LS-DYNA. In this example an analysis of a fuzzy process is performed by means of cluster methods and "-level discretization in order to select collapse sequences, significantly differing from each other and having other degrees of possibility.

• H-Point Machine and Head Restraint Measurement Device Positioning Tools – Extended Capabilities

  B. Walker, L. Cowlam, J. Dennis (Arup), S. Albery, N. Leblanc (Futuris)

  The H-point of a seat is an important parameter for in the design process of a vehicle, and in particular the design of a seat. This can be estimated empirically, but this method is usually not sufficient to accurately determine how the manikin’s position is affected by subtle yet complex interactions within the seat and its trim. To aid this process, Arup have developed a positioning tool kit for use in conjunction with the Oasys PRIMER software [1]. The positioning tool kit calculates the H-Points of the automotive seats, as well as the backset measurement, thus providing the scores of the head restraint.

• H-Point Machine and Head Restraint Measurement Device Positioning Tools and Validation

  Brian Walker, Liliana Cowlam, Jamie Dennis (Arup), Simon Albery, Nicolas Leblanc (Futuris)

  It is essential for seat manufactures to be able to accurately predict the H-Point position of a seat during the design stage, i.e. before the seat is actually built. This can be estimated empirically but this method is usually not sufficient to accurately determine how the manikin’s position is affected by subtle yet complex interactions within the seat and its trim. To aid this process, Arup have developed a positioning tool kit for use in conjunction with the Oasys PRIMER software [1]. The positioning tool kit calculates the H-Points of the automotive seats as well as the backset measurement thus providing the scores of the head restraint. The benefit to the seat engineer of using the Oasys HPM positioning tool is increased confidence in the H-Point of a new seat design, and an opportunity to adjust the design to minimise H-point variation that may be measured in test. This improved understanding of the seat will allow more accurate predictions of whiplash performance and other crash test simulations where dummy positioning is critical.

• Hail Impact Problem in Aeronautical Field

  A. Prato, M. Anghileri, L. Castelletti (Politecnico di Milano)

  Crashworthiness is one of the aspects that must be taken into account till the design phase, especially in aeronautical field. Some bodies, impacting against structures, can be considered as soft body. Soft bodies are highly deformable and flow over the structure spreading the impact load. Among them, hail impact can be considered as one of the most dangerous event during the operative life of aircrafts.

• Hail Impact Simulation on CFC Covers of a Transport Aircraft

  P. Starke, F. Mayer - EADS Deutschland GmbH

  Due to increasing weight saving requirements in new aircraft, structures traditionally built from aluminium alloys are increasingly replaced by carbon fibre reinforced Composites (CFC). For the preliminary flight clearance hail imact si- mulations were perfomed on CFC covers. For the composite material the authors applied a user- defined material. Behaviour of ice / hail stone was modeled through fitting of parameters for the Johnson–Cook material model to appropriate test data. While the precision of simulations was sufficient for a preliminary assessment, further tests will be necessary for permanent approval as well as for refinement of numerical models.

• Handling of large LS-Dyna Full Vehicle Crash Models with TECOSIM-advanced inhouse process Tools

  D. Lopez, U. Jankowski, S. Oldenburg - TECOSIM GmbH

  Based on several years of CAE experience TECOSIM has developed an advanced inhouse CAE process. Each TECOSIM tool was developed on the basis of TECOSIM internal projects as well as several projects carried out successfully at customers’ site. All tools used in this process are able to run as stand-alone solutions, but the combination of them provides a very effective CAE process, thus reducing the entire vehicle development cost. The TECOSIM modular principle makes one of the differences to other compact CAE process tools. TECOSIM ́s process is very flexible because each module can be run separately and it could be also added to almost any existing process.

• Handling of large LS-Dyna Full Vehicle Crash Models with TECOSIM-advanced inhouse process Tools

  D. Lopez, U. Jankowski, S. Oldenburg - TECOSIM GmbH

  Based on several years of CAE experience TECOSIM has developed an advanced inhouse CAE process. Each TECOSIM tool was developed on the basis of TECOSIM internal projects as well as several projects carried out successfully at customers’ site. All tools used in this process are able to run as stand-alone solutions, but the combination of them provides a very effective CAE process, thus reducing the entire vehicle development cost. The TECOSIM modular principle makes one of the differences to other compact CAE process tools. TECOSIM ́s process is very flexible because each module can be run separately and it could be also added to almost any existing process.

• HANS meets the GNS software Working with HBMs in Generator4 and Animator4

  Leyre Benito Cia

  New trends and developments in the automotive market have caused changes in the way we evaluate and analyze our vehicles. For example, the introduction into the market of vehicles with autonomous driving capabilities has led to an explosion in the number and variability of possible passenger positions within the vehicle cabin. Positions for which conventional dummy models have limitations due to the unidirectionality of their components and sensors.

• Head Impact Analysis Validation for Aluminium Bonnet

  O. Çolpan, F. Aras (Tofas)

  In recent years, vehicle manufacturers are making improvements to find more reliable solutions to pedestrian accidents. The manufacturers have to confirm these studies on some tests to carry out the requirements of international regulations. one of important these tests is head impact test. In the head impact test, one of the most important factors that affect the injury or fatality is bonnet. The subject of this article; in recent years, light weight vehicle is more important for fuel consumption and cost of vehicle. One of these studies will be examined by virtually analyzing how the aluminium bonnet impacted the head impact test,al and whether or not the pedestrians are damaged. In addition, the analysis will be correlated with the test to improve accuracy for future studies

• Head injury prediction tool for protective systems optimisation

  Deck Caroline, Willinger Rémy - Strasbourg University

  This paper presents an original numerical human head FE models followed by its modal and temporal validation against human head vibration analysis in vivo and cadaver impact tests from the literature. The human head FE model developed presents two particularities : one at the brain-skull interface level were fluid-structure interaction is taken into account, the other at the skull modelling level by integrating the bone fracture simulation. Validation shows that the model correlated well with a number of experimental cadaver tests including skull deformation and rupture, intra-cranial pressure and brain deformation. This improved numerical human head surrogates has then been used for numerical real world accident simulation. Helmet damage from eleven motorcycle accidents was replicated in drop tests in order to define the head’s loading conditions. A total of twenty well documented American football head trauma have been reconstructed as well as twenty eight pedestrian head impacts. By correlating head injury type and location with intra-cerebral mechanical field parameters, it was possible to derive new injury risk curves for injuries as different as subdural haematoma and neurological injuries. Illustration of how this new head injury prediction tool can participate to the head protection system optimisation is also provided.

• Head injury prediction tool for protective systems optimisation

  Deck Caroline, Willinger Rémy - Strasbourg University

  This paper presents an original numerical human head FE models followed by its modal and temporal validation against human head vibration analysis in vivo and cadaver impact tests from the literature. The human head FE model developed presents two particularities : one at the brain-skull interface level were fluid-structure interaction is taken into account, the other at the skull modelling level by integrating the bone fracture simulation. Validation shows that the model correlated well with a number of experimental cadaver tests including skull deformation and rupture, intra-cranial pressure and brain deformation. This improved numerical human head surrogates has then been used for numerical real world accident simulation. Helmet damage from eleven motorcycle accidents was replicated in drop tests in order to define the head’s loading conditions. A total of twenty well documented American football head trauma have been reconstructed as well as twenty eight pedestrian head impacts. By correlating head injury type and location with intra-cerebral mechanical field parameters, it was possible to derive new injury risk curves for injuries as different as subdural haematoma and neurological injuries. Illustration of how this new head injury prediction tool can participate to the head protection system optimisation is also provided.

• Head of Leveraging LS-DYNA Explicit, Implicit, Hybrid technologies with SGI hardware, Cyclone Cloud Bursting and d3VIEW

  Olivier Schreiber, Tony DeVarco, Scott Shaw (SGI), Suri Bala (LSTC)

  LSTC Explicit, Implicit solver technologies are closely integrated following LSTC's single executable strategy. Seamless switching from large time steps transient dynamics to linear statics and normal modes analysis can thus consistently exploit latest algorithm improvements in Shared Memory Parallelism (SMP), Distributed Memory Parallelism (DMP) and their combination (Hybrid Mode) and leverage SGI computer architectures using SGI's software stack, establishing `topcrunch' world records since 2007. 7KLV SDSHU ZLOO VKRZ KRZ WKLV LV DFFRPSOLVKHG RQ 6*,¶V PXOWi-node Distributed Memory Processor ® ® clusters such as SGI Rackable and SGI ICETM X up to Shared Memory Processor servers such as SGI® UV 2000 all available in SGI® CycloneŒ. Cyclone is a LS-DYNA® cloud computing service provided in partnership with LSTC. This paper will discuss how customers are using SGI's compute and storage infrastructure to run LS-DYNA simulations in a massively scalable environment. SGI's front-end to Cyclone is powered by d3VIEW Œ, a web portal based software used to submit, monitor and view results without the need to download large files. d3VIEW's SimlyzerŒ technology performs post-simulation analysis and visualization that is proven to eliminate over 80% of the LS- DYNA post processing repetitive tasks with no necessary scripting.

• Heat Transfer in LS-DYNA

  Arthur B. Shapiro - Livermore Software Technology Corporation

  LS-Dyna can solve steady state and transient heat transfer problems on 2dimensional parts, cylindrical symmetric parts (axisymmetric), and 3-dimensional parts. Heat transfer can be coupled with other features in LS-DYNA to provide modeling capabilities for thermal-stress and thermal-fluid coupling. This paper presents several examples using LS-DYNA for modeling manufacturing processes (e.g., upseting, extrusion, welding, casting).

• Heat Transfer in LS-DYNA

  Arthur B. Shapiro - Livermore Software Technology Corporation

  LS-Dyna can solve steady state and transient heat transfer problems on 2- dimensional parts, cylindrical symmetric parts (axisymmetric), and 3-dimensional parts. Heat transfer can be coupled with other features in LS-DYNA to provide modeling capabilities for thermal-stress and thermal-fluid coupling. This paper presents several examples using LS-DYNA for modeling manufacturing processes (e.g., metal forming, welding, casting).

• Heat Transfer Simulation to Determine the Impact of Al-5Mg Arc Sprayed Coating onto 7075 T6 Al Alloy Fatigue Performance

  G. D'Amours, B. Arsenault, F. Breton - National Research Council Canad, D. Dubé - Université Laval

  Aluminum-5% magnesium coatings was deposited by arc spraying onto aircraft Al 7075 T651 structural alloy for corrosion protection while required to maintain the substrate material fatigue performance integrity. Fatigue performance of coating system is complex and in order to better understand the variability of the fatigue performance of coatings, heat flow in substrate was studied and simulated to determine the temperature evolution during arc spraying in both substrate and coating for different process parameters. Experimental temperature measurements, theoretical calculations and simulation were carried out to extrapolate the coating temperature with respect to coating process variables and surface preparation. Both flux and conductance were identified by an inverse method to reproduce experimental temperature measurements. The thermal transient solver of LS-DYNA® was used to simulate the time-dependence of heat flux in the coating during successive depositions. The benefit of that model is its capability to predict the temperature distribution and evolution in time in a sample. Samples were made of Al 7075 T651 alloy and were 80 mm in length by 25 mm wide and 7 mm thick. A coating thickness of 250 μm was reached. It was the spray thermal energy that was taken into account in the model as the thermal load. The quality of the thermal contact between the substrate and coating was also included in the model and conductance was defined to control the amount of heat transferred at the interface. Coating performance was evaluated in term of fatigue properties, bond strength, and interface quality of as deposited coatings. The superior fatigue resistance of the coated alloy relies on low heat input process parameters and surface preparation that favor high interface conductance to keep low coating temperature during the coating process. Surface preparation, arc current and atomizing gases play all a key role to provide a fatigue resistant coating.

• Heat Transfer with Explicit SPH Method in LS-DYNA

  J. Xu (LSTC)

  In this paper, we introduce an explicit formalism to model heat conduction with Smoothed Particle Hydrodynamics method. With Taylor series approximation and SPH kernel interpolation, a simpler SPH discretization of the Laplace operator can be obtained for the thermal conduction equation. The formulation manifestly conserves thermal energy and is stable in the presence of small-scale temperature noise. This formalism allows us to evolve the thermal diffusion equation with an explicit time integration scheme along with the ordinary hydrodynamics. A series of simple test problems were used to demonstrate the robustness and accuracy of the method. Heat transfer with explicit SPH method can be coupled with structure for thermal stress and thermal structure coupling analysis.

• Hewlett Packard - Simulation Drives Move to Virtual Prototyping

  Surviving the economic slowdown by increasing cost-saving technology: Don’t spend more; spend more effectively Today’s trends - more complex features, increased global competition, and more government regulations - increase automakers’ reliance on CAE simulations HP and Intel help automakers maneuver through the obstacles by providing innovative technologies that boost computational performance and lower costs

• Hewlett Packard - Simulation Drives Move to Virtual Prototyping

  Surviving the economic slowdown by increasing cost-saving technology: Don’t spend more; spend more effectively Today’s trends - more complex features, increased global competition, and more government regulations - increase automakers’ reliance on CAE simulations HP and Intel help automakers maneuver through the obstacles by providing innovative technologies that boost computational performance and lower costs

• Hierarchical Multi-Level-Optimization of Crashworthy Structures Using Automatic Generated Submodels

  H. Singh, Prof. A. Schumacher (Bergische Universität Wuppertal); C. Falconi, A. Walser (Automotive Simulation Center Stuttgart); S. Trentmann, L. Benito (Iges. Für numerische Simulation); H. Müllerschön (Scale)

  The optimization of large crashworthy systems like a vehicle body in a crash loaded case is a time consuming and costly process. Extensive computer simulations are required to improve the crashworthiness of such large systems using an optimization technique. The simulation time can be reduced by dividing the large system into small subsystems also known as submodels. The submodels are used in the optimization to shorten the response time. But the generation of the submodels by hand is a challenging process and it requires a huge effort to validate them. This paper deals with the structural optimization of large crashworthy systems with a hierarchical Multi-Level-Optimization method using automatically generated and validated submodels. The process of automatic generation of submodels is developed using the so called connecting island algorithm [1]. The algorithm is developed in Tcl language using the software Generator [2] and Animator [3]. The two important parameters in this process are the threshold ratio and the connecting island value. These are based on an evaluation function which is a structural response of the large system with time averaging and space averaging method. The size of the submodel depends on these two parameters. Evolutionary algorithms are applied to optimize the time required to generate an appropriate submodel size with help of ClearVu Analytics [4] software. The process of automatic validation of submodels is based on three methods, so called local, global and response validation method which are discussed in detail. The Multi-Level-Optimization process is carried out in two hierarchical levels. The level 1 is a large system and level 2 is a submodel of the large system. Each level has different design variables, constraints and structural responses. The levels are coupled together using interface boundary conditions in form of nodal displacements. These boundary conditions are extracted from the large system and mapped onto the subsystem in an automatic process. If the boundary conditions are exact, the submodel region will deform identical to the deformation of this region in the large system [5]. The update of these boundary conditions and the correlation between the two levels is studied and discussed in detail. The research is demonstrated on an academic example of a cantilever frame impacted by a rigid sphere and on an industrial application of a Toyota Yaris front crash [6]. The future possibilities of the Multi-Level-Optimization method and the submodeling technique are shown in the paper.

• High Efficient and Powerful Integrated Design Support System "DYNA-Works”

  Fuminori Oshita, Osamu Kunieda - The Japan Research Institute, Ltd. (JRI)

  Nowadays, the CAE models are getting larger and more complicated. On the other hand, the simulation software including FEM codes, PRE-processors and POST-processors, must be quicker, more accurate and also easy to be used by various level customers. The authors introduce the developing high efficient and powerful design supporting system "DYNA-Works, completely specialized to LS-DYNA.” In this system, besides the general pre-post capabilities, the parts can be freely assembled into the simulation model. The response will be very quick even for the huge models. The data between PRE-POST systems and also among multi-stages problems will be connected seamlessly in this system. As a result, the total design cycle will be reduced very much.

• High Fidelity In-Bore Pressure Modeling

  Michael M. Chen - U.S. Army Research Laboratory

  Significant research efforts have been conducted to gain an in-depth understanding of projectile-weapon interactions at the U.S. Army Research Laboratory. The objective of this paper is to increase the fidelity of in-bore modeling and simulations that will facilitate the development of component and system models for U.S. Army weapon systems. Specifically, the in-bore pressure as a projectile travels through a gun tube, which has been known to be spatially and temporally varying distribution, will be programmatically taken into account in finite element analysis of launch dynamics. A computer program that embeds IBHVG2 Interior Ballistics code was implemented to automate the process. This tool can apply a substantial number of pressure curves to the corresponding barrel locations and generate LS- DYNA® compatible keyword files for analysis. The approach yields better accuracy and eliminates tedious manual efforts. In short, the development greatly streamlines the modeling efforts and significantly increases the fidelity of in-bore pressure modeling.

• High Performance Computing with CUDA and Tesla Hardware

  Dr Timothy Lanfear - NVIDIA

  The NVIDIA® TeslaTM C1060 transforms a workstation into a high-performance computing machine that outperforms a small cluster. This gives technical professionals a dedicated computing resource at their desk-side that is much faster and more energy-efficient than a shared cluster in the data centre. The Tesla C1060 is based on the massively parallel, many-core Tesla processor, which is coupled with the standard CUDA C programming environment to simplify many-core programming. Many applications have been ported to the CUDA architecture and show significant increases in performance compared with equivalent implementations on standard microprocessor architectures.

• High Performance Computing with CUDA and Tesla Hardware

  Dr Timothy Lanfear - NVIDIA

  The NVIDIA® TeslaTM C1060 transforms a workstation into a high-performance computing machine that outperforms a small cluster. This gives technical professionals a dedicated computing resource at their desk-side that is much faster and more energy-efficient than a shared cluster in the data centre. The Tesla C1060 is based on the massively parallel, many-core Tesla processor, which is coupled with the standard CUDA C programming environment to simplify many-core programming. Many applications have been ported to the CUDA architecture and show significant increases in performance compared with equivalent implementations on standard microprocessor architectures.

• High Performance Computing with Microsoft Windows: Meeting the Computational Requirements of Engineering Applications

  David A. Lifka - Cornell University

  The Cornell Theory Center (CTC) ran proprietary UNIX-based systems from IBM, SGI and others for over ten years as a national supercomputing center. Today, CTC is operating the world's largest Windows® scale-out systems with improved reliability, manageability, and total cost of ownership. This presentation focuses on the experience, benefits, and issues and key components for success CTC had moving from proprietary big-iron to industry-standard Windows clusters, to serve the midrange to high-end computing needs of their business, government and education clients. Of these clients, engineering applications are often the most computationally intensive and thus serve as good acid tests for the performance, reliability, and usability of HPC systems. The presentation will also include some representative performance results of LS-DYNA and other engineering codes running on Windows based computational clusters.

• High Speed Impact - Test and Simulation

  Prof. Dr.-Ing. habil. Stefan Hiermaier , Matthias Boljen, Dr. Ingmar Rohr - Fraunhofer-Institute for High-Speed-Dynamics

  Deformation processes of structures under dynamic loading have been investigated both experimentally and by simulation for many years now. Various rate dependencies in many materials, wave and shock wave phenomena as well as material tests for their quantitative description have been identified. In parallel, mathematical formulations for the observed material behavior and numerical schemes for time dependent approximations of the governing partial differential equations have been developed. Since both the experimental characterization and the numerical simulation demand for assumptions, e.g. the state and distribution of stress and strain in a specimen or in a discretizing unit, increasing complexity of materials demands for advanced test set-ups and numerical methodologies. In this paper, a brief discrimination between the regimes of quasi-static, low-dynamic and high-dynamic loading conditions is given. Related experimental means for material characterization as well as components in the numerical model needed to represent the relevant physical aspects are given by some example cases. Specific emphasis is placed on the characterization of low-impedance materials and on the implementation of a micro-continuum based fabric model into LS-DYNA. An application of the resulting fabric model to ballistic simulations is shown in the final part.

• High Speed Impact - Test and Simulation

  Prof. Dr.-Ing. habil. Stefan Hiermaier , Matthias Boljen, Dr. Ingmar Rohr - Fraunhofer-Institute for High-Speed-Dynamics

  Deformation processes of structures under dynamic loading have been investigated both experimentally and by simulation for many years now. Various rate dependencies in many materials, wave and shock wave phenomena as well as material tests for their quantitative description have been identified. In parallel, mathematical formulations for the observed material behavior and numerical schemes for time dependent approximations of the governing partial differential equations have been developed. Since both the experimental characterization and the numerical simulation demand for assumptions, e.g. the state and distribution of stress and strain in a specimen or in a discretizing unit, increasing complexity of materials demands for advanced test set-ups and numerical methodologies. In this paper, a brief discrimination between the regimes of quasi-static, low-dynamic and high-dynamic loading conditions is given. Related experimental means for material characterization as well as components in the numerical model needed to represent the relevant physical aspects are given by some example cases. Specific emphasis is placed on the characterization of low-impedance materials and on the implementation of a micro-continuum based fabric model into LS-DYNA. An application of the resulting fabric model to ballistic simulations is shown in the final part.

• High Strain Rate Testing and Material Modeling of an Anisotropic Glass Fiber Filled Polyetherimide

  Sean Teller, Ph.D., Jorgen Bergstrom, Ph.D., Veryst Engineering, Needham, MA

  High strength composite polymers are often used in applications that require high impact strength and durability. Accurately characterizing the mechanical behavior for FE simulation requires testing the materials at high strain rates and may require multiple loading modes. Veryst Engineering has developed high-strain rate experimental facilities for testing all classes of polymers. We tested 30% glass-fiber filled Polyetherimide (PEI) at engineering strain rates from 1 x 10-3 to 1.2 x 10+3 s-1 in uniaxial tension and compression.

• High Strain Rate Testing and Modeling of Polymers for Impact Simulations

  Jorgen Bergstrom, David Anderson, David Quinn, Eric Schmitt, Stuart Brown, Samuel Chow (Veryst Engineering, LLC)

  The increased use of polymeric materials in impact and high strain rate applications is motivating the use of impact simulations during design. However, simulation of polymer impacts requires difficult-to-measure stress-strain behavior at high strain rates. Even when appropriate data is collected, accurate high strain rate constitutive models need to be fit to the data before being incorporated into a simulation code. This article presents a testing and constitutive modeling process using Veryst’s PolyUMod® and MCalibration® to achieve accurate impact simulations using polyether ether ketone (PEEK) as the example material. Low and high strain rate data is presented over a large strain rate range. Validation of the developed material model is performed by simulating a drop test in LS-DYNA® with comparison to measured drop test data.

• High Velocity Impact Response of High Strength Aluminum using LS DYNA

  G. Başaran, E. Özbayramoğlu, O. Bütün, E. Öney (FNSS Savunma Sistemleri), Prof. E. Gürses (Orta Doğu Teknik Üniversitesi)

  Experimental and numerical studies were conducted to determine the impact response for high strength aluminum armor. A series of ballistic impact tests were carried out for the impact of a 20mm Fragment Simulating Projectile (FSP) with 25.4mm high strength aluminum armor plate at 960m/s impact velocity. This study deals with the measurement of ballistic limits of the deformable FSP against high strength aluminum armor material. The numerical models were developed using the explicit finite element code LS-DYNA®. All parts in the model are modeled with Modified Johnson-cook material model calibrated with performed tests in the company. Material properties are not shared due to confidential issues. A high-speed camera was used for calculation of projectile residual velocities and projectile output images. The numerical model was validated with live test results and a good agreement was achieved between experiments and numerical results. Parameter sensitivity analyses were performed to examine the effect of material model‘s parameters on the response.

• HIGH VELOCITY IMPACTS SIMULATIONS WITH SPH METHODS IN LS-DYNA

  Gilles Mazars, Gabriel Desille, Vincent Lapoujade - CRIL Technology - Groupe ALYOTECH, Christian Durin - CNES

  Several high velocity impacts (HVI) can be simulated using the SPH method in LSDYNA. Space debris, whose quantity is on the rise, now pose a major threat to satellites. Effective impact models enable both the development of more efficient protections and the prediction of the damage that an individual HVI will cause to structures. This paper aims to provide advice and words of caution on how to best model such impacts but also presents an example of a user implemented EOS in a SPH model. Usually, in the simulation of an HVI on a plate, both projectile and target are modeled using SPH parts. Commonly, the target model uses a tied transition from the SPH impact zone to the lagrangian parts which represent the undamaged area. This method reduces the number of elements in the model and the calculation time. The advantages and limits of the SPH method are presented first. The influence of the SPH/LAG transition on the quality of results is then discussed. Third, the influence of several SPH parameters on numerical results is mentioned. The number of particles used through the target thickness is of special interest, having a profound effect on the rear face cloud occurring after a perforation. Space debris can collide with satellites structures at velocities exceeding 10 km/s. In these conditions, commonly used EOS, such as the Gruneisen, for example, can not represent the material behavior during the expansion phase. The contribution of a user implemented EOS are presented for a HVI on an aluminium plate. The results are compared with experimental data to define optimized configurations as a function of impact velocity.

• High-Dynamic Drop Test Simulation for Fiber Reinforced Plastics in Automotive Electronic Control Units

  T. Zhao, D. Papathanassiou (Bosch Automotive Products)

  Short fiber reinforced plastics (SFRP) are widely utilized for electronic control units (ECU) in automotive fields. Failures in plastic parts often lead to re-tooling hence unpredicted increase in cost of manpower and time. Simulation indeed can offer the chance to virtual investigation without real samples therefore can deeply contribute in early development phase. As well known anisotropic material behavior induced by non-trivial fiber distribution of SFRP strongly influences local failure prediction. Moreover in high-dynamic drop problems viscoplasticity needs to be accounted to obtain the correct failure location. An oversimplified model or alternative isotropic approach in simulation can easily raise misleading results, while by being comprehensive in material model and tool chain one can respectively describe and include dominant influencing factors. To serve this interest, specimen made of reinforced polybutylene terephthalate with 30 wt% short glass fiber (PBT-GF30) are used for material characterization tests, mainly including 3-point bending and puncture tests by static and dynamic means respectively. By using 4a impetus an anisotropic LS-DYNA material card including the failure (DIEM) was determined reversely to describe the anisotropic viscoplasticity along with failure criteria applied in commercial program LS-DYNA®. Integrative tool chain with considering fiber distribution from process simulation to explicit structural simulation is implemented for an ECU level drop simulation, with which consistent ECU level drop tests are performed. By means of comparing critical drop height acquired from test, the feasibility of this tool chain simulation is shown.

• High-Mass, Low-Velocity Impacts on Reinforced Concrete Slabs

  A. J. Sangi, I. M. May- Heriot-Watt University Edinburgh

  The behaviour of reinforced concrete in quasi static regimes has been investigated extensively but there have been few investigations into its transient behaviour, especially under low velocity regimes. This paper describes the finite element modelling and analysis of reinforced concrete slabs under drop-weight impact loads using LS-DYNA. The results obtained from the numerical simulations have been compared with tests that were carried out at Heriot-Watt University to generate high quality input data to validate numerical modelling. The experiments were conducted on four 0.76 m and two 2.3 m square slabs under drop-weight loads. A drop-weight system was used to drop a mass of up to 380 kg with velocities of up to 8.7 m/s. The output from the tests included time histories of impact force, acceleration, strains and video footage using a high-speed video camera which recorded the images at the rate of up to 4,500 frames per second. The simulation results show reasonable agreement when compared to the tests and for the overall kinematic response of the slabs.

• High-Mass, Low-Velocity Impacts on Reinforced Concrete Slabs

  A. J. Sangi, I. M. May- Heriot-Watt University Edinburgh

  The behaviour of reinforced concrete in quasi static regimes has been investigated extensively but there have been few investigations into its transient behaviour, especially under low velocity regimes. This paper describes the finite element modelling and analysis of reinforced concrete slabs under drop-weight impact loads using LS-DYNA. The results obtained from the numerical simulations have been compared with tests that were carried out at Heriot-Watt University to generate high quality input data to validate numerical modelling. The experiments were conducted on four 0.76 m and two 2.3 m square slabs under drop-weight loads. A drop-weight system was used to drop a mass of up to 380 kg with velocities of up to 8.7 m/s. The output from the tests included time histories of impact force, acceleration, strains and video footage using a high-speed video camera which recorded the images at the rate of up to 4,500 frames per second. The simulation results show reasonable agreement when compared to the tests and for the overall kinematic response of the slabs.

• High-Strength Alloyed Steel: Modelling Dynamic and Multiaxial Loading Conditions

  A. Trippel (Institut für nachhaltige technische Systeme), W. Harwick (Fraunhofer EMI)

  This work reports on the modelling of failure behaviour in case of a high strength alloyed steel, experimentally subjected to a range of strain rates and states of stress triaxiality. This material combines high strength with exceptionally high ductility, which makes it difficult to describe material behaviour based on well-known constitutive models such as Johnson-Cook [1] [2]. To solve this challenge, extensive experimental investigations were performed to record stress-strain relations and, in particular, failure behaviour. Different states of triaxiality were attained based on the specimen geometry. Experiments with flat, unnotched and notched specimens yielded triaxial stress-states under uniaxial loading conditions. Stress-states due to shear stress and combinations of shear and tensile stresses were studied with biaxial tensile specimens. The triaxiality of the uniaxial tensile specimens was calculated based on the approximation suggested by Bridgman [3]. Based on the detected data, the material models suggested by Johnson-Cook [1] [2] was parameterized. Parameterization was carried out with the software LS-OPT [5]. The parameters of the constitutive models were found in an optimization procedure which minimized the difference between simulation prediction and experimental results. The discretization and element size was varied in order to study discretization effects. Smaller element sizes enabled a more constant triaxiality over the duration of the simulation. The parameter space of the Johnson-Cook model allowed for a satisfactory agreement in case of uniaxial experiments with a value of the stress triaxiality ≥ 1/3. However, the more complex problem of accurately modelling failure at other values of stress triaxiality between 0 (pure shear) and 1/3 (uniaxial tension) could not be solved. We discuss possible reasons for the apparent inability of the Johnson-Cook failure model to describe the effects induced by triaxiality at large failure strains and under shear stresses.

• High-throughput Simulation and Machine Learning Approaches for Can Body Design

  Maximilian Weiser, Sebastijan Jurendic

  Novelis is a world leader in aluminium flat rolled products and a major supplier to the beverage can-making industry. As such, Novelis is deeply involved in supporting the can-making industry to help shaping a more sustainable future together. Reducing the amount of metal used for each beverage can is a major driver for improving sustainability of the beverage can packaging, thus Novelis is actively investigating and developing state of the art modelling tools and approaches to support further optimization of the beverage can.

• Higher-Order 3D-Shell Elements and Anisotropic 3D Yield Functions for Improved Sheet Metal Forming Simulations: Part I

  Maximilian Schilling, Tobias Willmann, Alexander Wessel, Alexander Butz, Manfred Bischoff

  Sheet metal forming simulations are crucial in various industries, such as automotive, aerospace, and construction. These simulations are commonly carried out using Reissner-Mindlin shell elements, which involve certain simplifying assumptions about zero normal stress in shell normal direction and cross-sectional fibers remaining straight during deformation [1]. Because of this, the material model needs to be modified and no three-dimensional material model can be used. However, in critical forming situations such as bending with small radii relative to the sheet thickness, these assumptions do not hold, resulting in inaccurate simulation results. To address this issue, a higher-order 3D-shell element that incorporates a full three-dimensional constitutive model and that can account for cross-sectional warping and higher-order strain distributions has been developed [2].

• Higher-Order 3D-Shell Elements and Anisotropic 3D Yield Functions for Improved Sheet Metal Forming Simulations: Part II

  Alexander Wessel, Maximilian Schilling, Tobias Willmann, Alexander Butz, Manfred Bischoff

  This two-part series focuses on the industrial application of higher-order 3D-shell elements and anisotropic 3D yield functions in sheet metal forming simulations. In the second part, the effect of plastic anisotropy with respect to the in-plane and out-of-plane behaviour on sheet metal forming simulations is analysed. To this end, parameters of the anisotropic 3D yield function Yld2004-18p were identified by a crystal plasticity modelling approach for an AA6014-T4 aluminium alloy. Different loading conditions related to the plane and full stress state were carried out to study the plastic anisotropy with respect to the in-plane and out-of-plane behaviour.

• Highly Advanced M&S System for Marine Accident Cause Investigation using FSI Analysis Technique

  S. Lee (Korea Maritime and Ocean University)

  Investigation of marine accident causes usually depends on the judgments of maritime experts, based on the statements of the concerned persons in the case where there is no navigation equipment, such as AIS and VDR. Scientific verification also has a limitation in the case of their conflicting statements. It is necessary to develop a highly advanced Modeling & Simulation (M&S) system for the scientific investigation of marine accident causes and for the systematic reproduction of accident damage procedure. To ensure an accurate and reasonable prediction of marine accident causes, full-scale ship collision, grounding, flooding and sinking simulations would be the best approach using hydrocode, such as LS-DYNA, with its Fluid-Structure Interaction (FSI) analysis technique and propulsion force for ship velocity

• Highly Automated Springback Compensation of the Draw Die©

  Madhu Keshavamurthy, Junyue Zhang, Yiquan Tang, Xinhai Zhu, Volker Steininger, Thomas Schöbach

  Achieving a sheet metal part within dimensional tolerance without the need for tool recutting is the ultimate goal of every forming simulation. Several key factors are essential to reach this goal: an accurate forming simulation with precise material descriptions, correct friction val-ues, and an accurate binder model to determine the correct material flow and stress state of the part after forming. Additionally, an accurate springback calculation is required, considering the part clamped in the measurement device and the effect of gravity. With these results the new tool geometry has to be determined to compensate the springback of the sheet metal part.

• Honeycomb Modeling for Side Impact Moving Deformable Barrier (MDB)

  Moisey B. Shkolnikov

  Usually honeycomb is used as an energy absorber under impact loads. LS-DYNA constitutive model MAT-26 (*MAT_HONEYCOMB) is to mathematically model honeycomb as an energy absorber. The NHTSA MDB is a physical model of a typical impacting vehicle in side impact tests. The frontal part of MDB is made of honeycomb not just as an energy absorber but as a physical model of a typical car front end. Therefore, here the use of MAT-26 has some particularities, which are described in the paper. The MBD LS-DYNA model has been successfully used at GM for the last ten years.

• Honeycomb Sandwich Material Modeling for Dynamic Simulations of Aircraft Interior Components

  S. Heimbs, P. Middendorf - EADS, M. Maier - Institute for Composite Materials (IVW)

  An approach for modeling sandwich structures with a Nomex® honeycomb core and phenolic composite faces in the commercial finite element code LS-DYNA with solid elements for the core and shell elements for the thin faces is presented, which accounts for the major sandwich failure modes. Extensive material testing was conducted to determine the parameters for the composite face material model and for the orthotropic honeycomb material model. Strain rate dependency of the material parameters as well as face-to-core debonding phenomena were also investigated and included in the model. In order to design aircraft interior components for dynamic loads, finite element models of lateral and center bins of a widebody aircraft cabin were created and simulations of different load cases were performed. A good correlation to experimental dynamic test results could be achieved.

• Horizontal Tailplane Subjected to Impact Loading

  M. Hörmann, U. Stelzmann - CAD-FEM GmbH, Germany, M.A. McCarthy - University of Limerick, Ireland, J.R. Xiaoc - University of Delaware, USA

  The European Union Research Programme CRAHVI (CRashworthiness of Aircraft for High Velocity Impact) is concerned with the high velocity impact of aircraft due to flying objects, e.g. bird, hailstone, tyre and engine debris as well as concerned with survivable crash landings on different surfaces, e.g. rigid inclined surfaces (slopes) and water with different sea states. The simulation is naturaly a complex task due to the high number of variables involved. Such variables include material characteristics of the impacted media, impactors and surfaces at high strain rate, and the interaction between the aircraft structure and the impactors or surfaces. But with the increase of software and hardware computing power, it is now becoming more realistic to predict the behaviour of aircraft structures subjected to high velocity impact scenarios. Within the CRAHVI-Programme finite element models of a clamped horizontal tailplane (HTP) in an airliner are developed, which are subjected to impact loading with different impactor models. The HTP model composed of advanced composite material has been delivered by the University of Limerick [2],[3] whereas the HTP model representing metallic material was provided by the University of Patras [4]. Based on these models, the National Aerospace Laboratory NLR delivered an input file for the impact of a Lagrangian bird model on the HTP [8]. All files have been provided in form of PAM-CRASH input. It was the task of CAD-FEM to transfer those models into LS-DYNA input files, whereby special attention must be paid on a proper translation of the corresponding material models and the automatic generation of spotwelds. In case of the used composite bi-phase material the *MAT_LAMINATED_COMPOSITE_FABRIC model of LS-DYNA [11] is used. Based on those translated input files selective simulations for the composite and metallic structure are performed including bird strike on the leading edge (LE) of the HTP. For the bird strike simulation a Lagrangian as well as an ALE formulation is used. Additionally LS-OPT [10] was used in the Lagrangian bird strike simulation performing a thickness optimization of the LE. The optimization goal for bird strike is shortly speaking a non- rupture of the LE. The current contribution presents simulation results of rigid pole impact on composite HTP model, bird strike within Lagrangian formulation on metallic HTP model and bird strike within ALE formulation on metallic HTP model. Moreover the results are compared with other numerical results available within the CRAHVI-Programme. Additionally optimization results of the LE obtained from LS-OPT in combination with LS-DYNA are shown, which fulfill the desired optimization criterion of a non-ruptured leading edge.

• Hot Rolling Simulation of Aluminium Alloys using LS-DYNA

  P. Simon, G. Falkinger (AMAG); S. Scheiblhofer (Leichtmetallkompetenzzentrum Ranshofen )

  Aluminium and its alloys are widely used and applications of aluminium alloys can be found in all kind of industries, from packaging to transportation, from consumer electronics to architecture and lighting. In order to obtain a better understanding of the production process of aluminium alloy plates and sheets AMAG rolling GmbH strengthens the use of coupled thermo-mechanical finite element methods in combination with microstructure based user defined material models. The presented work shows a hot rolling simulation, which is an important step of the process chain. A detailed overview of 2D and 3D models for multi pass simulations is given and a graphical user interface for an automated simulation setup is presented. With the help of a Python based routine the virtual billet is trimmed and remeshed after each rolling pass in order to reduce the computational time. A comparison of the implicit simulation to the explicit simulation regarding the computational time is made and some simulation results are shown. Furthermore a comparison of the obtained rolling forces and temperatures between measurements of the hot rolling mill and simulation is given for an industrial pass plan.

• Hourglass Reduction Measures in Hard Turbine Missile Impact into Concrete Protective Barrier

  A. Iliev, M. Miloshev (Mott Macdonald)

  Failure of rotating machinery in nuclear power stations may result in ejection of fragments with high kinetic energy. Pieces of the disk or blades of a damaged turbine may cause failure of surrounding systems, structures, and components. The current paper presents study of effect of turbine disk fragment ejected as hard missile on the capacity of the protective walls of safety-related nuclear building. The investigation is performed by the missile-target interaction method, i.e. impact simulation of the model of the missile (i.e. the disk fragment) into the model of the protective barrier. Detailed model of the target is generated utilising non-linear material models for rebar steel and concrete. Different scenarios are investigated to define the most unfavourable impact with respect to the protective capacity of the safety barrier. The acceptance criteria are adopted form the relevant international regulatory documents. Special emphasis is given to the hourglass reduction. Various options are studied such as the hourglass control keywords, mesh refinement and different element formulation. The outcome in terms of CPU time and fulfilment of the structural acceptance criteria is compared and conclusions are drawn.

• How to Develop a Five Star Car by using LS-DYNA

  R. Malcusson - Saab Automobile AB

• How to Make LS-DYNA Run Faster

  Guangye Li, Jeff Zais - IBM Deep Computing Team

• How to Use LS-OPT for Parameter Estimation – hot stamping and quenching applications

  Arthur Shapiro - LSTC

  The “direct” heat transfer problem is one in which material properties and boundary conditions are specified, and LS-DYNA [1] is used to calculate the temperature response of the nodes in the mesh. The “inverse” heat transfer problem is one in which the temperature response of a node point in the mesh (e.g., a surface node) is specified from experimental measurements, and the objective is to calculate material properties and boundary conditions that cause this temperature response. This paper describes how to use LS-OPT [2] to solve the “inverse” heat transfer problem. Applications include: - calculating material parameters for austenite-to-martensite phase change kinetics, fitting material properties to experimental data - calculating contact heat transfer coefficients as a function of temperature and pressure during hot stamping, fitting a function to experimental data - calculating boiling heat transfer coefficients for quenching in liquids , fitting a load curve to experimental data

• How to Use the New CESE Compressible Fluid Solver in LS-DYNA

  Zeng-Chan Zhang - Livermore Software Technology Corporation

  This new solver is based on the conservation element and solution element (CESE) method[1, 2]. The CESE method is a novel numerical method for solving conservation laws, and it has many nontraditional features, such as: space- time conservation; high accuracy (2nd order for both flow variables and their spatial derivatives); novel shock- o capturing strategy; both strong shocks and small disturbances can be handled very well simultaneously, etc. o Because of these advantages, this CESE solver is a good choice for high-speed compressible flows with complex shocks and acoustic (noise) problems (near field). The solver has also been used to solve fluid/structure interaction (FSI) problems. For these problems, the fluid solver is based in an Eulerian frame while the structure solver is a Lagrangian frame. Their meshes are independent of each other, and the structural boundaries (fluid-structure interfaces) are tracked by the fluid solver automatically. The fluid solver gets the displacements and velocity of the interfaces from the structural solver and feeds back the fluid pressures (forces).

• HPC Considerations for Scalable Multidiscipline CAE Applications on Conventional Linux Platforms

  Stan Posey - Panasas, Inc.

  This paper examines HPC workload efficiencies for sample multidiscipline LS-DYNA applications on a conventional HPC Linux platform with proper balance for I/O treatment. Model parameters such as size, element types, schemes of implicit and explicit (and coupled), and a variety of simulation conditions can produce a wide range of computational behavior and I/O management requirements. Consideration must be given to how HPC resources are configured and deployed, in order to satisfy growing LS-DYNA user requirements for increased fidelity from multidiscipline CAE.

• HPC in the Cloud: Gompute Support for LS-DYNA® Simulations

  Iago Fernández, Gompute S.L.U.

  During the last decades, companies have been introducing CAE simulations as part of their product development with the main objective of improving reliability and reducing the costs of prototyping. It is nowadays demonstrated that introducing simulations during an early step of the product design process reduces the risk of failure as well as the associated costs, when the prototypes need to be redesigned.

• HPC Manufacturing White Paper.pdf
• HPC on the Cloud: Gompute Support for LS-DYNA Simulations

  I. Fernandez, R. Díaz (Gridcore)

  Gompute delivers comprehensive solutions for High Performance Computing, in-house, in the cloud or both. With over 10 years’ of experience providing solutions and services to the Engineering communities, Gompute delivers a collaborative and productive infrastructure to either manage your HPC environment or burst out into the Gompute data center , ranging from 1 > 1000’s of cores. Keywords: Cloud Computing, LS-Dyna on demand, HPC simulations, flexible capacity.

• Human Body Model Positioning using Oasys PRIMER

  G. Mohamed, G. Newlands (Arup)

  Human body models (HBMs) are detailed bio-fidelic finite element models of the human body and are primarily used to simulate human body kinematics and injury responses and risks in a variety of simulated impact scenarios. The current generation of HBMs, such as the industry leading THUMS and GHBMC family of models, encompass different genders, ages, and physiques, including detailed skeletal structures, internal organs (including the brain) and other soft tissues like skin, flesh and ligaments. Some HBM model variants also include muscle-activation features to simulate changes in occupant posture, taking into account changes in musculature activity, prior to a vehicle collision. Thus, combined emergency manoeuvres and crash events, or other long duration crash events, can be simulated.

• Hybrid IGA/FEA Vehicle Crash Simulations with Trimmed NURBS-based Shells in LS-DYNA

  L. Leidinger, S. Hartmann (DYNAmore), D. Benson, A. Nagy (ANSYS/LST) L. Rorris, I. Chalkidis (BETA CAE Systems), F. Bauer (BMW Group)

  Isogeometric Analysis (IGA) [1] is a rather new approach to Finite Element Analysis (FEA), using spline basis functions known from Computer Aided Design (CAD) for describing both the geometry and the solution field. The main motivation for IGA is the integration of design and analysis. Achieving such a full integration requires a holistic approach with a fundamentally different modeling strategy and development process to exploit the full potential of IGA. Such changes certainly take time and cannot be achieved overnight. Fortunately, IGA with its higher-order and higher-continuity elements also offers several additional advantages such as an accurate geometry description, superior analysis qualities, a larger explicit time step size or smart modeling techniques. Thus, users may benefit from IGA immediately, even without a full paradigm shift.

• Hybrid III 95th Percentile Large Male Finite Element Model Neck Alteration

  Eric Day, Christoph Maurath Sommer (Livermore Software Technology), Jacob Putnam, Chuck Lawrence, Preston Greenhalgh (NASA)

  The motivation behind the project was to update the Livermore Software Technology Corporation Hybrid III 95th percentile finite element model, such that the neck assembly response under varying simulated loading conditions equals that of the federally regulated Hybrid III 95th percentile anthropomorphic testing device (ATD). The former neck model was poorly correlated to that of the physical Hybrid III neck in corresponding tests. Adjustments were made to mass and geometry, element formulation, and element discretization to improve model durability and accuracy. Test data from a physical compression test and NASA-performed Neck Sled Tests were collated with data from simulation to adjust material properties. The neck rubber material was further calibrated according to Code of Federal Regulations (CFR) neck calibration test response requirements. The resulting neck model developed in LS-DYNA® exhibited improved dynamic characteristics and reliability under both low and high severity loading. Computational efficiency was enhanced along with model stability under excessive loading. The revised neck model will be adopted by NASA for use in predicting potential occupant injury during spacecraft landing.

• Hybrid Laminated Glass: Material Characterisation and CAE Modelling

  B. Feng (JaguarLandRover)

  Different from standard laminated glass which is made of from soda-lime glass, hybrid laminated glass comprises layers of standard soda-lime glass, PVB and chemically toughened glass. Hybrid laminated glass has advantage of weight saving, so it has drawn great attentions to the automotive industry recently. However, its application may have impacts not only to the performances of many attributes, safety, NVH, etc., but also to the CAE modelling method which we have adopted for the standard laminated glass. This paper discusses the research activity of understanding potential impact of hybrid laminated glass application, the method of material characterisations, CAE modelling development for different safety attributes.

• Hydrodynamic Drag Force Predictions for Amphibious Military Vehicles

  I. Kurtoglu (FNSS Savunma Sistemleri)

  Amphibious military vehicles are very important in the battle field due to their flexible operating environment. In general, amphibious military vehicles are designed for water operations in still lakes and rivers with low current speed. There are also some examples of amphibious military vehicles operating in open water environment with harsh sea state conditions. Having this operational flexibility makes the amphibious military vehicles strategically important for armies. However, making a military vehicle amphibious brings challenging problems especially in the design stage. Drag force prediction is obligatory for the thrust requirement determination. High drag forces mean high thrust requirements which may also affect the selected thrust system. Due to high thrust demand, the system may be bigger, and hence heavier, and this weight increase may affect the amphibious performance of the vehicle. Therefore, estimating the drag forces for defined amphibious operation conditions is very important. Also, optimizing geometrical form of the vehicle according to the amphibious capability of the vehicle becomes more important. In this study, the drag forces on an amphibious military vehicle at different operation velocities are predicted using Incompressible Computational Fluid Dynamics (ICFD) solver implemented in LS-DYNA®. In the simulations, the vehicle model is scaled according to the Froude number used in the verification tests. The test scale is limited by the pool dimensions. The drag tests are performed in Istanbul Technical University Naval Architecture and Design Faculty laboratories. Drag force predicted from the simulations for a predefined speed is compared with the one obtained from the pool tests. The accuracy of the drag force estimated from simulations is reviewed for different solution parameters of LS-DYNA® ICFD solver.

• HYDROPLANING SIMULATION USING FLUID-STRUCTURE INTERACTION IN LS-DYNA

  Masataka Koishi, Toshihiko Okano - The Yokohama Rubber Co.,Ltd., Lars Olovsson - LSTC, Hideo Saito, Mitsuhiro Makino - Fujitsu Ltd.

  The hydroplaning phenomenon is a key issue for safe driving on a wet road. However, it has been extremely difficult to predict the onset of hydroplaning using numerical simulation. The hydroplaning is a complex multi-physics problem, involving rolling tires with complex groove geometry and surrounding water. Recently the fluid-structure interaction capability has been developed for both Eulerian and ALE formulations in LS-DYNA. Using this capability, transient hydroplaning can be modeled for both the reference frame fixed on a moving car (Eulerian fluid) and the reference frame fixed on the ground (ALE fluid). In the present work, both tire and fluid are modeled with Finite Elements. Numerical examples of the passenger car radial tire sized 195/65R15 with V-shaped grooves are illustrated. In the proposed simulation, we obtain a tire completely lifted by the water layer. In addition, the difference in lifting velocities between normal rotational direction and reverse rotational direction has been evaluated. The numerical results correspond well to the experimental observations at a proving ground.

• Hypervelocity impact of aluminium sphere against aluminium plate : experiment and LS-DYNA correlation

  F. Plassard, J. Mespoulet, P. Hereil - Thiot Ingenierie

  High velocity impact of 3 mm diameter aluminium sphere against thin aluminium target plate has been performed at impact velocity of about 4000 m/s with the two stage light gas gun HERMES at Thiot Ingenierie laboratory. Impacts at normal incidence and with a 32° angle generate debris clouds that were collected by an aluminium witness plate. The visualization of the debris clouds generated after the impact has been realized by using an ultra high speed framing camera. LSDYNA 3D Smooth Particle Hydrodynamics and 2D&3D Multi- Material ALE solvers (MMALE) were used to reproduce debris clouds generation and expansion in the two angle configuration. Agreement between simulations and experimental frames are discussed.

• ICFD: Summary of Recent and Future Developments

  Since its release in R7 the Incompressible CFD solver (ICFD) has been rapidly improving and increasing its functionality. In this paper a summary of the latest and current developments will be presented. The focus will be on four topics. First the steady state solver and its coupling capabilities for fluid-structure interaction (FSI) or conjugate heat transfer (CHT) will be presented. In second place the recent modifications to the boundary layer mesh generation will be introduced where some default parameters have changed. The possible implications of these changes in the solution will be mentioned. Third a short introduction to coupling ICFD with LS-OPT® for shape optimization will be presented. The idea is to use ANSA to morph the surface mesh driven by LS-OPT to provide an optimal solution. Finally some of the current developments will be enumerated like immersed interfaces, periodic boundary conditions, porous media through shell elements for parachute simulation, etc. These developments will be part of future LS-DYNA® releases.

• Ideas on Applying Very Fine Models in Dummy Model Development

  Uli Franz, Alexander Gromer, Jens Zschieschack - DYNAmore GmbH, Matthias Walz - Mercedes Car Group, Daimler AG, Yupeng Huang - Sunrise Auto Safety Technology

  Very fine models allow investigating the behavior of dummies with high accuracy. Even if ele- ment numbers for a dummy model above 3 Million elements are currently not suitable for stan- dard simulation in vehicle development, the usage of such models contribute to the development of coarser dummy models. Due to the detailed representation physical effects occurring can be captured very realistically with the very fine models. The paper present current methodology to develop models within the FAT or PDB frame work and outlines first experiences with very fine models to enhance coarse dummy models.

• Identification of an advanced hardening model for single phase steels

  Muhammad Noman, Bob Svendsen - University of Dortmund

  Sheet metal forming processes cover a wide range of applications in industry. In order to model sheet metal forming processes using numerical simulation an accurate description of the material behavior is required. To this end a material model has been implemented which is capable of capturing the move- ment and proportional expansion of the yield surface along with the change in the shape of the yield surface. The former is described as kinematic and isotropic hardening, respectively, and the latter is termed as distortional (cross) hardening. Once the model is implemented the second step consists in identifying the material parameters. In this contribution, a strategy for the identification of material param- eters is presented. The strategy is based on identifying the isotropic hardening, combined hardening (isotropic-kinematic hardening), and complete hardening model (isotropic-kinematic-cross hardening) sequentially, in such a way that the parameter values identified in the previous step are used as start- ing values for the next step. Hence, the isotropic and kinematic hardening are first identified using the monotonic shear and Bauschinger shear test data, then the distortional (cross) hardening effect is de- termined using orthogonal tension-shear data using the isotropic-kinematic hardening parameter values as starting values. The material model was implemented in LS-DYNA using user defined material and LS-OPT based parameter identification for the steels LH-800 and DC06 is performed. The identified pa- rameters are first validated and then used in F.E. simulations using ABAQUS and LS-DYNA. A complete account on application of identified material model is presented in the talk ”Numerical investigation of draw bending and deep drawing taking into account cross hardening” presented at this meeting.

• Identification of an advanced hardening model for single phase steels

  Muhammad Noman, Bob Svendsen - University of Dortmund

  Sheet metal forming processes cover a wide range of applications in industry. In order to model sheet metal forming processes using numerical simulation an accurate description of the material behavior is required. To this end a material model has been implemented which is capable of capturing the move- ment and proportional expansion of the yield surface along with the change in the shape of the yield surface. The former is described as kinematic and isotropic hardening, respectively, and the latter is termed as distortional (cross) hardening. Once the model is implemented the second step consists in identifying the material parameters. In this contribution, a strategy for the identification of material param- eters is presented. The strategy is based on identifying the isotropic hardening, combined hardening (isotropic-kinematic hardening), and complete hardening model (isotropic-kinematic-cross hardening) sequentially, in such a way that the parameter values identified in the previous step are used as start- ing values for the next step. Hence, the isotropic and kinematic hardening are first identified using the monotonic shear and Bauschinger shear test data, then the distortional (cross) hardening effect is de- termined using orthogonal tension-shear data using the isotropic-kinematic hardening parameter values as starting values. The material model was implemented in LS-DYNA using user defined material and LS-OPT based parameter identification for the steels LH-800 and DC06 is performed. The identified pa- rameters are first validated and then used in F.E. simulations using ABAQUS and LS-DYNA. A complete account on application of identified material model is presented in the talk ”Numerical investigation of draw bending and deep drawing taking into account cross hardening” presented at this meeting.

• Identifying Traumatic Brain Injury (TBI) Thresholds Using Animal and Human Finite Element Models Based on in-vivo Impact Test Data

  Keegan Yates, Costin Untaroiu (Virginia Tech)

  Traumatic brain injuries (TBIs) cause roughly 50,000 deaths per year in America. In order to lessen the severity or prevent TBIs, accurate dummy models, simulations, and injury risk metrics must be used. Human data is ideal to develop models, but injury conditions are often complex, e.g. primary and secondary impacts, and tissue level response can often only be studied via an autopsy, but death usually only occurs as the result of severe TBI. To develop better graded injury risk metrics, animal study data must be applied to the human brain. The ultimate objective of our study was to develop a better method to scale injury data by using finite element analysis (FEA). In this study, a finite element model of a Göttingen miniature pig brain and skull was created from MRI and CT images. These pigs’ brains have several characteristics in common with human brains that that make them suitable for testing such as shape and material properties. The regions of the brain were divided into white matter, gray matter, and the ventricles each with viscoelastic material properties. To validate this model, tests were conducted using Göttingen miniature pigs in a translation/rotation injury device subjecting the pig skull to a linear acceleration from 40-96 g’s and an angular acceleration from 1,000-3,800 rad/s 2 . Four of these pigs’ brains were embedded with neutral density radio-opaque markers to track the motion of the brain with a biplanar X-ray system. Fifteen pigs were also tested without markers to allow for injury data to be taken with MRI scans and immunohistochemistry. The impact was then simulated in LS-DYNA ® , and the motion of nodes closest to the marker locations was recorded and used to optimize material parameters. When used in tandem with a human model this will allow for a more accurate transfer function to scale injury data from a pig study to be relevant to humans. While the loading conditions in this study simulate a small range of possible injuries, the scaling methods involved may be applicable to a wide variety of injuries from sports injuries to blasts.

• IIHS Side Impact Analysis Using LS-DYNA/Madymo Coupling

  Jiri Kral - TNO Madymo North America, Prabhu Setru, Swarna Rajeswaran - General Motors

  The LS-DYNA/Madymo coupling has a growing popularity in the field of vehicle crash analysis as it allows the users to merge an existing occupant simulation subsystem model and a full car structural model into one system. The extended coupling feature introduced in late 2002 has significantly enhanced this model fusion capability. This paper demonstrates the application of such a coupling technique for the simulation of the IIHS (Insurance Institute for Highway Safety) side impact condition on one of General Motor's vehicle development programs. However, when this analytical work was originated, the test configuration was new and still not completely defined. The baseline model consists of the vehicle structure and barrier model in LS-DYNA, and occupant and airbag models in Madymo. The baseline model was modified to demonstrate an enabler that helped improve side impact performance.

• IIHS Side Impact Parametric Study using LS-DYNA®

  Reichert, R., Kan, S., George Mason University, USA;, Arnold-Keifer, S., University of Stuttgart, Germany;, Mueller, B., Insurance Institute for Highway Safety, USA

  Side impact crashes are the second most common reason for vehicle passenger deaths after frontal crashes. In 2003, the Insurance Institute for Highway Safety (IIHS) introduced its side impact crash test using a Moving Deformable Barrier (MDB) to encourage manufacturers to implement safety improvements, including side airbag coverage and stronger side structures, in most vehicle models. While many vehicles were rated poor in the beginning of testing in 2005, most of the vehicles were rated good in 2015. Improved IIHS ratings are associated with a more than 30% reduction in passenger deaths in multiple-vehicle side impact crashes. Of the remaining fatal side impact crashes, the majority are occurring at a more forward impact location and higher severity compared to the IIHS test. For this reason, the IIHS is planning a series of full-scale tests to evaluate the effect of different impacting vehicles and test setups with respect to today’s test protocol. For reducing costly, time-consuming, and complex full-scale testing, finite element (FE) simulations play an important role and are successfully used in vehicle safety research and development.

• Image Based Meshing for LS-DYNA

  Brian Walker - Arup, Philippe Young - Simpleware

  Simpleware provides what is effectively a 3D photocopier: three dimensional replicas can be generated automatically based on scans. In parallel, computer simulations can be used to assess the suitability or performance of objects in operation. Simpleware's technology has opened up FEA and RP manufacturing to a variety of applications and research fields including: • Industrial reverse engineering • Research in materials and composites • Non-destructive evaluation (NDE) • Biomechanical Research • Implant design and manufacturing • Surgery simulation and planning • Forensics • Biomimicry Simpleware software can be used in conjunction with the “Oasys LS-DYNA Environment” to make an efficient toolkit for the creation and running of models in LS-DYNA.

• Immersed Interface Development in Incompressible CFD

  Facundo Del Pin, Iñaki Çaldichoury, Rodrigo R. Paz, Chien-Jung Huang (Livermore Software Technology LLC)

  The pre-processing of complex geometries exported from CAD programs is a big challenge in the Finite Element analysis of fluid problems. There are many situations where a detailed high quality mesh is preferred and possible mandatory. Such is the case for problems where shear stresses are an important component of the total force, i.e. ground vehicle aerodynamics, aircraft drag prediction and some bio-mechanics applications where the stresses in the endothelium are need to predict the development of some diseases. There are many other applications though where pressure forces are enough in terms of accuracy or where rapid prototyping of engineering parts do not need the accuracy required in the final stages of engineering design. In these cases, the geometry could be simplified by approximating the domain walls immersing them inside a much simpler domain. This simplification becomes even more appealing in the presence of an internal structure that interacts with the fluid which in many engineering applications are modeled as thin shell structures. In the current work the sub-element interfaces of the geometry will be approximated by level set distance functions. The walls could be part of a flexible structure or they could be rigid and they may be "wet" on both sides. The pressure discontinuity across the wall (in the case of shell structural elements) will be approximated by discontinuous shape functions as described in [1]. One of the main advantages of this approach is that it is easily adapted to an existing solver since no additional degrees of freedom need to be added. The presentation will include details of the additions that the existing solver needed such as: 1) boundary recognition; 2) level set representation; 3) sub-element splitting; 4) computation of the new interpolation functions and integration; 5) assembly and solution.

• Immersive Visualization and Collaboration with LS-PrePost-VR and LS-PrePost-Remote

  Todd J. Furlong - Inv3rsion, LLC

  This paper describes two new branches of LS-PrePost that are designed to work together to extend LS-PrePost with immersive visualization and collaboration capabilities. LS-PrePost-VR supports immersive visualization on a wide range of immersive displays, including CAVE-like devices, large-screen displays, and head-mounted displays. The software can run on either a single computer, a visualization cluster, or an SMP machine. By itself, LS-PrePost-VR supports command-line reading of supported file types as well as playback of command files generated by desktop versions of LS-PrePost. A VR input device provides an intuitive interface that includes animation control, an interactive clipping plane, and selection capability. LS-PrePost-Remote is a client application that connects to the LS-PrePost-VR application and allows input to the application through the traditional LS-PrePost GUI. Multiple remote clients can connect to and synchronize with a VR session, allowing collaborative analysis on a corporate intranet. The paper discusses software design and implementation, as well as possible future directions for this software. LS- PrePost-VR and LS-PrePost-Remote are developed and supported by Inv3rsion, a software engineering firm located in Goffstown, New Hampshire.

• Impact Analysis of a 16t Truck against different Road Safety Restraint Systems

  Elisa Oldani, Luigi Castelletti, Marco Anghileri, Mario Mongiardini - Politecnico di Milano, Italia

  In this work, the Finite Element model of a 16-ton truck suitable for the numerical analysis of the impact with road safety devices is described. The possibility to correctly reproduce the behaviour of both the vehicle and the barrier before the actual testing is greatly helpful in the design of restraint systems and it can avoid failure of tests. Particular attention was paid in modelling features of the truck such as frame, suspensions and tyres, which play a central role in determining the vehicle behaviour during the impact. The truck model complies with the requirements for the homologation of H3-type barriers, in accordance with the European standard CEN EN 1317. Impacts against two different restraint systems were considered: a concrete New Jersey-type barrier and a H3-type steel deformable barrier. The simulations were carried out using LS-Dyna 970 that has shown to be particularly suitable for this kind of analysis. Eventually, results have showed the reliability of this model for the design and analysis of safety barriers.

• Impact Analysis of an Innovative Shock Energy Absorber and its Applications in Improving Railroad Safety

  X. Xin, B. K. Parida, A. K. Zaouk, N. Dana, S. K. Punwani

  Short Fiber Reinforced Thermoplastics (SFRT) such as glass filled Polyamide 6 and 66 have been widely adopted as a metal replacement in a wide range of industries. The main advantage of using these materials is high strength to weight ratio, light weight, parts consolidation, easy manufacturability etc. Continuous Fiber Reinforced Thermoplastics (CFRT) are also gaining popularity because of its ability to achieve high directional stiffness/strength by tailoring the number of layers and angles. Applications which combine these two by over molding SFRT on CFRT inserts are still in its infancy. One of the hurdles is the lack of good CAE simulation capability for such applications. This paper describes the CAE tools that are developed using LS-DYNA to successfully model static and dynamic behavior of such parts. Material 58 in LS-DYNA is used for modeling the CFRT material while a User Defined Material Law models the SFRT material and they are coupled together through suitable contact definitions. Its applicability is verified through a number of examples varying from very simple to complex configurations

• Impact Analysis of Polymeric Additive Manufactured Lattice Structures

  G. Laird (Predictive Engineering), P. Du Bois (Consultant)

  This work was sponsored by the US Army’s Natick Soldier Systems Center to investigate additively manufactured lattice structures for improved blunt impact protection for helmets. The idea is simple enough, modern helmets are designed to deflect or mitigate the impact forces due to bullets (high velocity) but not so much for blunt force impacts (lower velocity). In military operations, blunt force impacts are common, albeit sometimes accidently, due to falls or in the rush to enter-exit buildings and vehicles. In combat, flying debris also present challenges to helmet designers where the impacts can be both high- and low-velocity. Our work was to set the foundation for the exploration of polymeric 3D lattice structures to create the next generation of energy-absorbing helmet liners for military applications. Current foam liners, whether multi-layer or sculptured, all exhibit more-or-less the same energy-absorbing response which is fine for high-energy impacts but lacks the sensitivity for low-energy impacts. If one can move away from the use of foam and toward that of a 3D polymeric lattice structures, then it should be possible to engineer a helmet liner to have a more variable or tailored energy-absorbing response. To create such structures, the additive manufacturing process was used.

• Impact and Detonation of COMP-B: An Example using the LS-DYNA EOS: Ignition and Growth of Reaction in High Explosives

  L. E. Schwer (Schwer Engineering & Consulting Services)

  The LS-DYNA keyword *EOS_IGNITION_AND_GROWTH_OF_REACTION_IN_HE provides the ability to model the ignition and growth of the reaction in high explosives via shock initiation from an impact or donor explosive. In this preliminary assessment effort, the experimental results for projectile impact on COMP-B of Almond and Murray (2006) are simulated. In addition to reporting their experimental results, the authors also reported numerical simulations results. Further, Urtiew et al. (2006) reported numerical simulation results for this set of experiments, using the same ignition and growth of the reaction in high explosives equation of state, Lee and Traver (1980,) implemented in LS-DYNA, but using a different explicit hydrocode. The experiments reported by Almond & Murray were for a blunt brass projectile impacting COMP-B without and with cover plates made from steel, aluminum and high density polyethylene. The critical impact speeds were in the range 950 to 1350 meters/second (2000 to 3000 miles/hour). Their numerical simulations used AUTODYN with the Lee and Tarver ignition and growth model. Similar experiments are reported by Lawrence et al. (2002 and 2006) which also included impact of COMP-B with steel cover plates by projectiles. This series of experiments considered different cover plate thicknesses, projectile nose shapes, and impact obliquity of the projectile. Critical impact speeds ranged from about 1050 to 1600 meters/second for the normal impact cases. The experimental configurations were simulated using the CTH (Hertel et al., 1993) code with the History Variable Reactive Burn (HVRB) explosive initiation model (Kerley, 1995). These experiments are not simulated in the present manuscript, but recommend to interested readers. In this manuscript the ignition and growth of the reaction in high explosives equation-of-state is introduced along with model parameters for COMP-B. Some comments are included in this section concerning alternative versions of these model parameters that are available in the literature. The manuscript focuses on the experimental data of Almond and Murray, their simulations results, the simulations results of Urtiew et al. and the present results, which make use of the relatively new LS-DYNA axisymmetric Multi-Material Arbitrary Eulerian Lagrange (MM-ALE) capability and thus serve as a post-test form of model validation.

• Impact of Soft Body Materials, an Experimental and Numerical Approach using a Hopkinson Tube: Application to Substitute Bird

  J. Pernas-Sánchez, R. del Caurillo, J.A. Artero-Guerrero (University Carlos III of Madrid)

  Aeronautic and Aerospace industries permanently seek to optimize structural components due to the high safety and reliability requirements. These improvements in the structures should withstand severe case of loads to accomplish the certification processes; traditionally the designers use experimental tests to validate it. The use of virtual testing could reduce the development times and costs but this needs reliable material models to produce accurate results. Load cases for aeronautic structures are extensive, but among others, impact is one of the most concern loads for the structures. Literally from an EASA 2011 report[1] “A critical safety issue for the design of primary aircraft structures is vulnerability and damage tolerance due to foreign object impact from bird strike, hail, tyre rubber …”, highlighting the impact threat as a key factor in structure design. Thus, for reliable damage prediction in virtual testing, it is necessary to obtain appropriate data and develop modeling techniques for this kind of soft impactors. In this work, a combined experimental-numerical methodology is presented to validate material models for deformable impactors under impact; applying it to a real case of study: the bird impact. In the experimental campaign substitute birds (SB), made from gelatin, are launched against a Hopkinson tube to measure the stress pulse generated in the tube [2], capturing the kinematics of the impactor using high speed cameras. The results obtained have been compared with a numerical model to prove the feasibility of the combined experimental-numerical methodology. The numerical model for the Hopkinson tube and the SB was implemented in LS-Dyna. Prior to simulate the impact, the numerical model of the Hopkinson tube was validated by means of comparing the modal frequencies experimentally measured and numerically obtained. For this purpose, the modal package included in the implicit module of LS-Dyna was employed. Once the Hopkinson tube model was validated, the bird impact was simulated using the explicit module. The SB was defined using SPH, this meshfree approximation was selected due to the large deformation suffered by the SB during the impact. The constitutive behaviour of the gelatine was modelled as a fluid like material with a polynomial equation of state, the material properties were obtained from the literature ([4][5]). The results predicted agree with the experimental data (Figure 1), so the combined methodology was proved to be useful for material models calibration under impact conditions. The validated numerical simulations have been used to study the robustness of the experimental technique under impact drifts that can be occurred during the experimental tests (i.e. changes in the impact location or impact angle…).

• Impact Performance of Flexible Guardrail Systems using LS-DYNA

  Khaled Sennah - Ryerson University, Magdy Samaan - University of Windsor, Ahmed Elmarakbi - University of Toronto

• Impact Simulations of Fiber Reinforced Plastics with LS Dyna and Digimat

  M. Palm (Husqvarna Group)

• Impact Simulations on Concrete Slabs : LS-OPT Fitting Approach

  Nicolas VAN DORSSELAER, Vincent LAPOUJADE - Alliance Services Plus, Georges NAHAS, François TARALLO, Jean-Mathieu RAMBACH - Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-roses

  This paper is based on a work realized for an international OECD benchmark initiated by IRSN and CNSC. The main goal of IRIS_2010 Benchmark was to evaluate the ability of simulation to reproduce experimental tests of impacts on concrete slabs for two different deformation modes: bending (flexural) and punching. LS-DYNA® has been chosen by IRSN as their main explicit code for simulating such high speed impacts on concrete. Most LS-DYNA® concrete laws include two sets of physical parameters, a first one related to basic concrete parameters (Compressive strength, Poisson ratio), a second one related to each concrete model (Damage, strain rate effects). LS-DYNA® provides an automatic generation capability for the second set of parameters (based only on the Compressive strength) which leads to an acceptable level of accuracy for the majority of cases. However, this automatic set of parameters can usually be optimized to better fit experimental results. For each benchmark case, we performed an advanced 3 steps fitting approach using LS- OPT®. A Monte Carlo analysis was done first on several model parameters to study sensitivities and correlations and identify which ones can affect the slab damage and may improve the results. Then, an Optimization of identified parameters was realized to fit the experimental results. Finally, a complementary Monte Carlo analysis on physical parameters (Concrete resistances, Poisson’s ratio...) was used to evaluate the robustness of our optimal solution and to integrate in our calculation process uncertainty and variations of material data.

• Impact Simulations on Home Appliances to Optimize Packaging Protection: A Case Study on a Refrigerator

  D. Hailoua Blanco, A. Ortalda (Engin­soft), F. Clementi (Electrolux Italia)

  Numerical simulations were used to investigate the impact behavior of complex products such as home appliances. LS-DYNA® is a powerful tool for performing repeat analysis of large assembled parts of the final product, including the packaging. The main goal of the simulations was to verify the performance and suitability of the packaging and its interaction with the structure in case of damage occurring during transportation or delivery. The studies were carried out to guarantee the integrity of the product from factory to customer and therefore to reduce customers service calls.

• Impact Test Simulation for Nuclear Power Plant Safety under Tornado Disaster

  Sunao Tokura, Tokura Simulation Research

  In recent years, the safety standards of nuclear power plants against natural disasters, e.g., earthquake, tsunami, tornado, have been extremely intensified in Japan. Regarding the influence of tornadoes, the magnitude and the wind velocity of tornado and the geometry, dimensions, mass, impact velocity and other properties of the missiles from tornado are regulated in detail and the safety measures supposing the impact of the missile to certain vulnerable zones in nuclear power plants are required. Concerning the structures composed with steel plates in the buildings of nuclear power plants, the countermeasure to prevent the penetration of the missile to the structures should be considered.

• Impingement jet flows for cooling using LS-DYNA®: an introduction to ISPH and ICFD approaches

  E. Yreux, I. Caldichoury (Ansys/LST)

  Cooling jet flows are commonly encountered in many industrial applications where fast and strong heat dissipation is required such as in pistons, gears, electrical engines and so forth. With the rapid growth and acceptance of simulation as a companion tool intervening directly in the design process, there is a need to provide fast and robust numerical solutions that can provide information on flow patterns and cooling efficiency.

• Implementation and Validation of the Johnson-Holmquist Ceramic Material Model in LS-Dyna

  Cronin D. S., Kaufmann C. - University of Waterloo, McIntosch G., Bui K., Berstad T. - LSTC

  Ceramic materials are commonly used in protective armour applications and may be subject to high-energy ballistic impacts in these situations. Under simple loading conditions, ceramics may be regarded as elastic-brittle materials. However, when considering ballistic impacts, the post-yield response of the ceramic becomes significant. One of the most widely used constitutive models for simulating the postyield response of ceramic materials is the JH-2 ceramic model. This constitutive equation was developed by Johnson and Holmquist and incorporates the effect of damage on residual material strength and the resulting bulking during the compressive failure of a ceramic material. The relevant equations describing the response of the material are described. In particular, the model parameters currently available for common ballistic ceramic materials are presented. The JH-2 constitutive model has been implemented in LS-Dyna as material 110 (*MAT_JOHNSON_HOLMQUIST_CERAMICS). Validation against the available test cases in the literature is discussed, and a sample calculation of a sphere impacting a ceramic material is presented. The JH-2 model in LS-Dyna has also been used by Kaufman et al. to successfully simulate the ballistic impact of 12.7 mm armourpiercing projectiles on supported alumina tiles.

• Implementation and Validation of an Advanced Hypoplastic Model for Granular Material Behavior

  Montaser Bakroon, Reza Daryaei, Daniel Aubram, Frank Rackwitz, Chair of Soil Mechanics and Geotechnical Engineering, Technische Universität Berlin, Berlin, Germany

  Problems in soil mechanics and geotechnical engineering are often characterized by large deformations and complex material behavior. For example, the mechanical behavior of granular materials like sand is highly nonlinear due to the presence of an evolving internal structure formed by the grains. The strength and stiffness is generally a function of the stress and density state and the loading history. While LS-DYNA® has proved to be among the most robust hydrocodes for modelling large deformations and dynamic problems, it currently does not provide material models capturing granular material behavior over a wide range of stress and density states under monotonic and cyclic loads with only one set of parameters for a specific granular material and incorporating state parameters such as void ratio.

• Implementation of a Constitutive Model for Aluminum Foam Including Fracture and Statistical Variation of Density

  A. Reyes, O. S. Hopperstad, T. Berstad, M. Langseth - Norwegian University of Science and Technology

  An existing constitutive model applicable to aluminum foam was implemented in LS-DYNA. One main objective in the present project was to implement a model that could handle fracture in the foam. Therefore, two simple fracture criteria were also implemented in the model. Additionally, the possibility to include initial statistical variation of the foam density was incorporated in the model so that inhomogeneities in the foam properties could be represented. Foam subjected to both simple and more complex loading conditions where fracture was of varying importance have been analyzed, and some representative results and comparisons with experimental data are presented. The implemented model is efficient and robust, and gives good results. The model including one of the fracture criteria and without the possibility of statistical variation of density is at present available in version 970 of LS-DYNA.

• Implementation of a material model with shear rate and temperature dependent viscosity

  Mathias Vingaard, Benny Endelt, Jesper deClaville Christiansen - Aalborg University

  A material model with shear rate and, optionally, temperature dependent viscosity was implemented. Shear rate dependence is expressed with a Yasuda function and temperature dependence with an Arrhenius function. The functions were fitted to viscosity data from oscillatory rheometry of polystyrene. Validation of the viscosity function in the material model was done with a single element with prescribed shear rate and temperature. Steady state results from a Newtonian simulation of plane Poiseuille flow with the implemented user material model were found to be identical to results from a simulation with LS-DYNA's MAT_NULL. Flow through a 4:1 contraction with shear rate dependent viscosity was simulated explicit and compressible as well as implicit and incompressible. Reasonable agreement was found for pressure loss, inlet force and outflow velocity.

• Implementation of a material model for TRIP-steels in LS-DYNA and comparison with test results

  Daniel Hilding - Engineering Research Nordic AB, Erik Schedin - AvestaPolarit AB

  This paper describes the implementation of a new material model into LS-DYNA version 960, LSTC (1-4), a material model capable of predicting the TRIP-effect of HyTensX for different forming operations in different temperature scenarios. The implementation is verified by comparing measurements from three tension tests with simulations of the tension tests. The comparison shows good to excellent agreement, which is a strong indication that the implementation is correct and that the material model can be used to predict the hardening behavior of the material with good accuracy.

• Implementation of a Method for the Generation of Representative Models of Polycrystalline Microstructures in LS-PrePost

  S. Falco (Imperial College London), N. Bombace, N. Petrinic (University of Oxford), P. Brown (DSTL)

  The capability of accurately reproducing the microstructural features of polycrystalline materials is of fundamental importance for the correct simulation of the micromechanical behaviour of materials. This paper describes the development and the implementation of VorTeX algorithm for the generation of numerical models representative of real polycrystalline microstructures, and its integration within LS-PrePost. The method presented offers high control over the grain size distribution of the final structure by adopting the so-called Laguerre-Voronoi tessellation techniques. Additional features implemented allow constraints to be imposed on the structure such as symmetrical boundaries and enables the introduction of interface entities (i.e. contacts and cohesive elements) on the grain boundaries to model inter-granular crack propagation.

• Implementation of a New Continuum Damage Mechanics Model for Composites in LS-DYNA®

  Danghe Shi, Xinran Xiao (Michigan State University)

  A large amount of work has been done to simulate the crashworthiness of composite structures, particularly to evaluate the deformation behavior and to determine the energy absorbing efficiency. However, the existing simulation models generally need to introduce many non-measurable parameters which limited their practical applications. This work focused on the implementation and development of a thermodynamically consistent continuum damage mechanics (CDM) model called Ladevèze model. This model took into account stiffness recovery and inelastic strains, both damage and plastic strains. All the parameters needed in this model can be determined by experiment. Modified Ladevèze models were developed in order to adapt different damage and plasticity evolution laws for different fabric forms of composites. Three different versions of Ladevèze model were implemented in LS-DYNA and their predictive abilities were studied.

• IMPLEMENTATION OF A NOVEL SHIP SIDE STRUCTURE INTO A TANKER AND A ROPAX VESSEL FOR INCREASED CHRASHWORTHINESS

  Sören Ehlers, Kristjan Tabri, Nicole Schillo, Janne Ranta - Helsinki University of Technology

  The energy absorption of a novel ship side structure is numerically analysed. The structure is implemented into an ice going Tanker and a ROPAX vessel. The aim is to evaluate the benefits in crashworthiness of such an application over the existing conventional side structures. The collision simulations are performed with the explicit non-linear solver LS-DYNA up to the point of inner shell breaching. The obtained energy-penetration curves of the novel structure are then compared to energypenetration curves of the conventional structure. The novel sandwich structure results in clear benefits in terms of increased energy absorption during collision; 30 per cent for the Tanker, and about 50 per cent for the ROPAX. The applied failure criterion and mesh size dependency are also discussed.

• Implementation of a Strain Rate Dependent Human Bone Model

  Zahra Asgharpour, Erich Schuller, Steffen Peldschus - Institut für Rechtsmedizin der Universität München, Dirk Fressmann - Dynamore GmbH

  Strain rate dependency of mechanical properties of cortical bone has been well demonstrated in literature studies. Nevertheless, the majority of these studies have been done on nonhuman bone and at lower magnitudes of strain rates. The need for a mathematical model which can describe the mechanical behavior of bone at lower strain rates as well as higher ones is essential. A human finite element model THUMS (Total Human Model for Safety) [1], developed by Toyota R&D Labs and the Wayne State University, USA has been applied for this study. This work proposes an isotropic elastic-plastic material model of cortical bone where rate effects have also been considered.

• Implementation of a User Material Routine in 3D-FE Codes for Viscoelastic Modeling and Simulation of Highway and Airport Pavements

  W. Uddin, L. Ricalde - The University of Mississippi

  Traditional static analysis procedures using linear elastic pavement properties may lead to incorrect structural response analysis of pavements. Many of these procedures do not appropriately consider the effects of dynamic loading and pavement nonlinearities such as joints and cracking. It is imperative to use appropriate and correct material properties for meaningful advanced computer simulations. This paper presents some results of traditional analysis and three dimensional-finite element simulations carried out on selected pavement- subgrade models of highway pavements. Results of static and dynamic analysis are presented using measured falling weight deflectometer (FWD) load pulses and deflections. Effects of viscoelastic material properties on pavement responses to dynamic FWD loading are investigated. A user defined material subroutine UMAT is described. The UMAT material routine incorporates a generalized Maxwell viscoelastic model and microcracking propagation methodology. The UMAT material routine is being implemented in the LS-DYNA code.

• Implementation of Constitutive Model for Thermoplastics with Some Preliminary Results

  Torodd Berstad - SINTEF Materials and Chemistry, Odd Sture Hopperstad, Arild H. Clausen - Norwegian University of Science and Technology, Norway, Håvar Ilstad, Bjørn Melve - Statoil ASA

  This paper presents an implementation of a material model for thermoplastics. Such materials have a quite complex behavior involving large elastic and plastic deformations, strong viscous and temperature effects, possible true stress softening and deformation-induced anisotropy. The demand of reliable constitutive models for thermoplastics is increasing, and a promising approach is due to Haward and Thackray (1968), who separated the response in two processes: one flow process related to motion of polymer chain segments, and one extendable spring based on the conventional theory of elastomers. Several researchers have extended the Haward and Thackray model, and in particular, the group headed by Boyce at MIT has worked with modeling of polymers for years. The implementation in this paper is mainly based on a paper by Boyce et al. (2000). Recognizing the large elastic deformations in polymers, we have used a framework with a Neo-Hookean hyperelastic material description. The semi-implicit stress update algorithm is as proposed by Moran et al. (1990). Predictions using the implemented model is compared with results from uniaxial tension and compression tests on polypropylene. The agreement is satisfactory in both cases of loading, as the main features of the force-deformation curve and yield stress difference in compression and tension are reproduced by the model.

• Implementation of Constitutive Equations for Viscoplasticity with Damage and Thermal Softening into the LS-DYNA Finite Element Code, with Application to Dynamic Fracture of Ring- Stiffened Welded Structures

  Ricardo F. Moraes, David W. Nicholson - University of Central Florida

  Constitutive equations for a viscoplastic model with damage and thermal softening are implemented in the Finite Element (FE) code LS-DYNA using a User Defined Subroutine UMAT. A modified Johnson-Cook constitutive model, UMAT 15, which accounts for strain rate viscoplastic effects, is used. The Continuum Damage Mechanics (CDM) is based on Bonora formulation (Bonora, 1997). The combined material model, named UMAT 41, is added to the program static library using Digital Visual Fortran (FORTRAN 90). A brief procedure on how to implement a UMAT is also briefly discussed in this work. Using the User Defined Material, the solution of an explosive charge applied to a ring-stiffened welded structure is analyzed. This type of structure is widely used in ships and aircraft, which are subject to explosive or projectile attack. Results obtained using models with and without damage softening agree very well with previously published data with respect to crack paths. However, the time histories and thresholds are sensitive to the model used.

• Implementation of MCEER TR 14-0006 Blast Load Curves in LS-DYNA® and Benchmark to Commonly Practiced Blast Loading Application Methods

  Devon Wilson, Deborah Blass, and Sam Noli, Arup

  A tool has been developed to explore implementation of the blast load curves derived by J. Shin, A. Whittaker, A. Aref and D. Cormie in the MCEER Technical Report 14-0006 (2014). The MCEER proposed blast load curves capture the effects of high explosives near the face of the charge, where the traditionally-used Kingery and Bulmash (KB) empirical data is not applicable. Although not a replacement for a proper computational fluid dynamics assessment, designers can use simplified methods such as this tool to provide rough order of magnitude assessments prior to performing more complex and time intensive hydrocode methods.

• Implementation of Modal Representation for Full Vehicle VPG Simulations

  Xianggang Zhang - Engineering Technology Associates, Inc.

  The modal representation method matured in LS-DYNA 970. It is a useful tool for full vehicle, long duration Virtual Proving Ground (VPG) analyses. The CPU time for VPG analysis could be dramatically reduced with such application. Modal representation method uses linear combination of the pre-calculated mode shapes to represent portion of the full vehicle model in transient dynamic analysis. The linear modal response of this portion of vehicle is superimposed to the full vehicle’s nonlinear explicit analysis. The explicit element processing is only applied to the rest of the model and thus reduces the total CPU time. A pickup vehicle was used in this study to demonstrate the application of this method to full vehicle VPG analysis. The mode shapes of the pickup box were calculated and superimposed to full vehicle VPG analysis. While the results were compatible to the results from a traditional explicit analysis, significant CPU time was also reduced by using this method.

• Implementation of Peridynamic Theory to LS-DYNA for Prediction of Crack Propagation in a Composite Lamina

  T. Kahraman (MAN Turkey/ TOBB University of Economics and Technology), U. Yolum, M. A. Guler (TOBB University of Economics and Technology)

  Composite materials are commonly used in aerospace and automotive industry due to their high specific strengths. However, damage tolerance assessment of composite parts is done experimentally since there is no single criterion that is capable of predicting all of the failure modes. Thus numerical estimation of crack propagation in composite structures has been considered as an important research topic in academia and especially in aerospace industry. Composite materials are sensitive to stress raisers such as fastener holes and defects.

• Implementation of the Projected Subgradient Method in LS-TaSC™

  Willem Roux, Imtiaz Gandikota, ivermore Software Technology Corporation;, Guilian Yi, Dalian Fukun Technology Corporation

  The projected subgradient method is major new methodology development for the topology optimization of huge, multi-disciplinary structural problems; for example, the combined impact, statics, and NVH design of a whole body in white. This paper accordingly discusses the projected subgradient method in LS-TaSC, with specific reference to the basic theory, the ability to combined impact and NVH load cases, and the performance for huge models. Also mentioned is how the method has been enhanced to handle generalized constraints using the multi-tensor numerical scheme.

• Implementation of the Tanimura-Mimura's Strain Rate Dependent Constitutive Model in LS-DYNA Using User Defined Material Model

  Dr. T. Tsuda - ITOCHU Techno-Solutions Corporation, Dr. S. Tanimura - Aichi University of Technology, Dr. A. Abe, Dr. M. Katayama, Dr. T. Sakakibara - ITOCHU Techno-Solutions Corporation

  Tanimura-Mimura constitutive model covers a wide range of the strain rates and of a large strain, and enables us to use unified and common material constants to simulate the dynamic behaviors of materials and/or bodies. In this paper, dynamic behaviors of high speed tensile tests, buckling tests and crash test of a full vehicle are simulated by implementing this model in LS-DYNA®. Obtained numerical results are in good agreement with the experimental ones and the validity of the model has been demonstrated.

• Implementations of User Defined Shell Elements and Material Models to LS-DYNA and Their Application

  J.W. Yoon, R.E. Dick - Alcoa Technical Center

  Robustness, accuracy and good computational performance for large scale models are some of the salient requirements for general purpose finite element programs. A new one point quadrature shell element that meets these requirements has been previously developed in the works of Cardoso & Yoon (2005). In the theory, the finite element strain-displacement matrices are described in a convective coordinate system for the efficient implementation of a physical stabilization procedure. In order to increase the computational efficiency of the shell element, in this work the resultant-stress equations are formulated by reducing dimensionality to the shell's mid- surface. In order to improve the simulation accuracy of sheet metal forming simulation utilizing commercial software, the proposed one-point quadrature element and a typical fully integrated element have been implemented to LS-DYNA using the user element interface. In addition, a plane stress yield function (Yld2000-2d, Barlat et al. (2003)) and a new anisotropic model (Yld2004-18p, Barlat et al. (2005)) that accurately describe the anisotropic behavior of aluminum alloy sheets were also implemented to LS-DYNA user material option (UMAT). Several examples including sheet forming are presented to demonstrate the element's robustness and efficiency and to verify the interface.

• Implicit and Explicit Finite Element Simulation of Soft-Pad Grinding of Silicon Wafers

  A.H. Zhao , Z.J. Pei, X.J. Xin - Kansas State University

  Silicon wafers are used to fabricate more than 90% of all integrated circuits. Surface grinding is the preferred technique used to flatten wire-sawn wafers. While conventional grinding is not effective in removing the waviness induced by wire-sawing process, experiments and finite element analysis indicated that soft-pad grinding is a promising method to remove waviness effectively. This paper presents the simulations of the process of the waviness removal of wire-sawn wafers by both implicit and explicit finite element methods using ANSYS and LS-DYNA respectively. Contact algorithms are important in the simulation of wafer grinding. Since the wafer thickness and pad thickness are in the range of millimeters which is thin in comparison with the wafer diameter (in the range of hundreds of millimeters), and the waviness height is usually in the range of tens of micrometers, selecting suitable penetration values in the contact algorithm is challenging. This paper is focused on the selection of contact model, element type, and other solution control parameters in both implicit and explicit methods. The study will be helpful for finding a generalized methodology in similar simulations of contact analysis.

• Implicit Functionality in LS-DYNA v970

  Dr. B. Maker, Dr. R. Grimes, Dr. C. Ashcraft - Livermore Software Technology Corp.

• Implicit SPH in LS-DYNA for Automotive Water Wading Simulations

  E. Yreux (LSTC)

  The explicit SPH solver implemented in LS-DYNA is well fitted for numerical simulations involving hypervelocity impacts, explosions and other transient events, but is unsuitable for slower fluid-flow simulations such as water wading. In this work, we introduce an implicit SPH formulation specifically developed for handling large-scale incompressible fluid simulations. The method is based on a traditional projection scheme: Intermediate velocities are first predicted based on external and viscosity forces contribution, and a Poisson equation is then solved to obtain pressure forces such that incompressibility is maintained up to a given tolerance. All the surfaces composing the structure are automatically sampled with SPH particles by LS-DYNA using a user-supplied maximum interparticle distance, and the fluid-structure interaction is embedded in the SPH solver directly. This aspect of the simulation does not require any contact card to be setup. As the simulation evolves, the initial domain decomposition performed by LS-DYNA can become inefficient, triggering increasing communications across processors and poor load balancing, resulting in an increasing CPU time per simulation cycle as the SPH fluid particles intermix. A new feature has been developed based on the full-deck restart capability of LS-DYNA. The objective is to re-decompose the domain across processors at regular intervals, based on the updated geometry of the problem. This results in a more constant simulation time and overall improved performance.

• Importance of Plasticity for GISSMO Calibration in Automotive Safety Applications

  Richard Burrows

  GISSMO has become an incredibly flexible tool since its inception. An overview is not to be presented here owing to the fact it is coved extensively by other authors. This body of work aims to show that even using simple techniques and features a robust GISSMO card is possible using only *MAT_024 and *MAT_ADD_EROSION, that can be useful in automotive safety, even with larger type 16 shell elements 3-6mm in edge length for gauges approx. 1-2mm. 3-6mm quad elements are a very useful size for automotive structures and allows accurate meshing of holes, flanges and joints for example.

• Improved Infrastructure Accessibility and Control with LSF for LS-DYNA

  Bernhard Schott, Christof Westhues - Platform Computing GmbH

• Improved LS-DYNA Parallel Scaling From Fast Collective Communication Operations on High-Performance Compute Clusters

  Lars Jonsson, Tim Prince - Intel Corporation

  Fast collective communications are a key to maintaining high parallel efficiency as the number of nodes increases on a cluster of high-performance servers. Profiling of LS-DYNA message traffic demonstrates that good parallel scaling requires fast communications of short messages - up to a few kilobytes - and in particular of collective operations involving short messages. Fast collective operations require both an efficient implementation of the message-passing operations in terms of message primitives and a high-bandwidth, low-latency interconnect. This paper demonstrates both these aspects by presenting parallel-scaling measurements on Intel Architecture based compute clusters with MPICH2 implemented over fast interconnects. The analysis evaluates both the benefits, at application level, of the emerging MPICH2 work from Argonne National Laboratories relative to MPICH1, and the benefits from the single-digit microsecond latencies offered by todays fastest interconnects. The paper also outlines how next- generation interconnect technologies and new, efficient, and flexible MPI implementations can even further improve both application performance and adaptability.

• Improved LS-DYNA Performance on Sun Servers

  Youn-Seo Roh, Henry H. Fong - Sun Microsystems, Inc.

  Current Sun platforms which are very competitive in price/performance include Linux servers using either the Intel Xeon or AMD Opteron processors. Benchmark results using the industry-standard Neon model are presented. Performance and scalability up to 32 CPU's are discussed, as well as a comparison of use of gigabit Ethernet (GBE) interconnect versus Myrinet in a Linux Xeon cluster. Current status of Solaris x86 porting of LS- DYNA is also presented.

• Improved Numerical Investigations of a Projectile Impact on a Textile Structure

  Gunther Blankenhorn - Universität Karlsruhe, Karl Schweizerhof - Dynamore GmbH, Hermann Finckh - Institut für Textil- und Verfahrenstechnik Denkendorf

  Past perceptions to the processes of the penetration mechanisms of projectiles acting on textile structures [1] are often based on continuum models [2] or simplified models [3] and admit only limited conclusions concerning the real behavior of protective clothing made from several layers of fabric. Only a few investigations are known up to now with models based on single yarns as a major component for discretization [4]. Thus, for the prediction of the protective effect of several layers of high-strength fibers in a textile, a structural approach is chosen by a separate modelling of each fiber by a shell or continuum based element. The single modelled fibers interact over a contact formulation with the adjacent fibers in the same way the fibers in the different layers do. This allows to model the in-plane motion and deformation of each fiber separately, as well as the failure of fibers thereby avoiding artificial localization effects to a great extent. With the so-called explicit finite element code LS-DYNA [8] different possibilities of the discretization of the fiber bundles are investigated. Also the description of the fiber material by available material models is varied modifying the load deformation relation and the damage evolution. The goals of the current project [10] are first to achieve a geometrically consistent model of the layered structure and second to better understand the phenomenological process of the impact of ballistic projectiles on such textiles. Finally, the particular effect of different layer setups can be studied. INTRODUCTION Up-to-date bullet proof vests are consisting of several layers of fabrics made of high performance fibers like Kevlar® (Du Pont), Twaron® (Tijin) and Zylon® (Toyobo). These vests have a specific weight up to 2000 g/m². Many so called “trial-and-error” tests have to be performed to improve the weight of this vests. So far, only few attempts are known to predict the behavior of new constructions, like new fiber materials or different fiber materials for different layers, by way of exploring the mechanical phenomena. Numerical simulations by a finite element program could be a useful tool to detect this phenomena and they would allow the developers to optimize their products. To perform a numerical simulation, some research into fiber and fabric geometry and their possibilities to approximate them through finite elements is necessary. Also, the material behavior of the fibers exposed by high velocity loading must be measured to choose a suitable material model. The objective of this paper is the description of the fabric geometry, the discretization by shell and solid elements and first investigations of the model behavior in the analysis. Weave geometry and fiber properties Fabric and fiber geometry Following the approach to discretize the weave through a collection of single yarns, the shape of the cross section and the curve through the center of gravity of the cross sections must be acquired. To get this information of an unloaded weave, two specimen of a Kevlar® weave were embedded in epoxy resin. One of them was roG – I - 08

• Improved Plasticity and Failure models for Extruded MgProfiles in Crash Simulations

  Gernot Oberhofer, Harry Dell, Dmitri Dell, Helmut Gese - MATFEM Partnerschaft Dr. Gese & Oberhofer Horst Lanzerath, Jürgen Wesemann - Ford Forschungszentrum, Elke Hombergsmeier - EADS Corporate Research Center

  The Crash Simulation of Magnesium Structures with Finite Element Methods demands the use of suitable material and failure models. An associated plasticity model describing the complex asymmetric yield behaviour in tension and compression of Mg extrusions has been developed during the InMaK-project (Innovative Magnesium Compound Structures for Automobile Frames) supported by the German Federal Ministry for Education and Research (BMBF). Differences to the material model 124 in LS-DYNA are exposed. In order to describe the failure behaviour of Mg extrusions under multiaxial loading in FEM crash simulation this constitutive model has been combined with a fracture model for ductile and shear fracture. The fracture model has been added to the user defined constitutive magnesium model in LS-DYNA. The experimental investigations carried out on model components are compared with numerical derived results. Experimental methods for fracture parameter evaluation are shown and general aspects of metal failure due to fracture as well as different modelling techniques are discussed.

• IMPROVED SPOTWELD SIMULATION WITH LS-DYNA - NUMERICAL SIMULATION AND COMPARISON TO EXPERIMENTS

  Karl Schweizerhof, Werner Schmid - CAD-FEM GmbH, Herbert Klamser - PORSCHE AG

  Functioning of the body of a car structure with respect to stiffness, durability and crashworthiness is mainly dependent on the connection between the manufactured parts, in particular, if mainly shell type structural parts are used. Spot welding is the dominant technique used nowadays to connect shell type parts. Though spot welding is a fully automated process and a well known technique since many years, there is little knowledge about the behavior of the spotweld connections under single strong impulse loading. This knowledge, however, is one major ingredient for a proper repre-sentation in FE crashworthiness models. In order to capture the correct mechanical behavior of a spotweld connection with its complex stress state, in prin-ciple a fully 3D continuum mechanical model is needed, e.g. as the welding process itself has a major influence on the material properties in the vicinity of the spotweld due to the high temperatures involved locally. In addition from experiments it is known that the failure process of a spotweld connection is strongly dependent on the form of the spotweld and local rupture takes place. In FE crashworthiness models, however, such detailed models cannot be incorpora-ted for the many thousands of spotweld connections due to efficiency reasons. Thus alternative models have to be developed to include the major effects of the spotweld behavior within full car crash models with only little influence on the efficiency of the FE analysis. Taking the experiences gained from many years of modeling in the automotive in-dustry a number of different FE spotweld models are discussed and the results of the analyses with LS-DYNA are compared to some experimental results from the investi-gations initiated by the FAT- working group 27 (Forschungsvereinigung Automo-biltechnik e.V. AK 27). Within the analysis particular focus is on the sensitivity of the results concerning the various spotweld models tested on single spotwelds. Finally the influence of the vari-ous models on the results for a realistic part under crashworthiness loading is shown.

• Improved Tool development Process for novel SCS Technology for Aluminium Sheet Metal

  Apostolos Papaioanu, Prof. Dr. Mathias Liewald MBA - Institut für Umformtechnik, Stuttgart, Ralf Schleich - HochschulInstitute Neckarsulm, Neckarsulm

  Today’s stretch forming technologies mainly are used for production of large and flat parts made of sheet metal mainly for the aircraft industry (wing fabrication) and for shipbuilding. Because of the high investment costs and high process time, the use of such conventional stretch forming technologies is not qualified for production of car body panels. However, benefits of present stretch forming methods such as improvement of the mechanical properties of these parts today makes stretch forming technologies attractive for automotive industry. For this very reason a new technology for stretch forming of sheet metals (Short-Cycle-Stretch forming SCS) has been developed at the Institute for Metal Forming Technology (IFU) at Universitaet Stuttgart [1]. The SCS technology combines a plane pre-stretching and subsequent deep drawing operation for production of small car body panels with high demands concerning surface quality. SCS technology is based on a low cost tool which is used in a single action deep drawing press with short process cycles [2]. Former investigations have shown the tremendous potentials of the SCS technology by using typical mild steel alloys for car body panels. Conducted investigations about theoretical achievable effective strain in the stretched region included experimental validation which approved an effective strain value of φ≈0.09 in the stretched region of the specimen [3]. In order to fulfil increasing environmental regulations, the automotive industry focuses on reducing car body’s weight by using lightweight materials such as aluminium or high strength steel. SCS technology offers the possibility of producing car body panels with high surface quality at a minimum of investment costs. Therefore it is necessary to verify SCS technology for new lightweight sheet metal materials as described in [3]. Because of the material properties of high strength steel it does not make sense to investigate such materials for their use with SCS technology regarding the denting resistance and the part stiffness. However, aluminium is due to lower material properties predestinated for a pre-stretching process to increase such properties. The SCS technology offers a huge potential for pre-stretching aluminium blanks and to produce parts with significant better part quality with regard to part stiffness and dent resistance.

• Improved Tool development Process for novel SCS Technology for Aluminium Sheet Metal

  Apostolos Papaioanu, Prof. Dr. Mathias Liewald MBA - Institut für Umformtechnik, Stuttgart, Ralf Schleich - HochschulInstitute Neckarsulm, Neckarsulm

  Today’s stretch forming technologies mainly are used for production of large and flat parts made of sheet metal mainly for the aircraft industry (wing fabrication) and for shipbuilding. Because of the high investment costs and high process time, the use of such conventional stretch forming technologies is not qualified for production of car body panels. However, benefits of present stretch forming methods such as improvement of the mechanical properties of these parts today makes stretch forming technologies attractive for automotive industry. For this very reason a new technology for stretch forming of sheet metals (Short-Cycle-Stretch forming SCS) has been developed at the Institute for Metal Forming Technology (IFU) at Universitaet Stuttgart [1]. The SCS technology combines a plane pre-stretching and subsequent deep drawing operation for production of small car body panels with high demands concerning surface quality. SCS technology is based on a low cost tool which is used in a single action deep drawing press with short process cycles [2]. Former investigations have shown the tremendous potentials of the SCS technology by using typical mild steel alloys for car body panels. Conducted investigations about theoretical achievable effective strain in the stretched region included experimental validation which approved an effective strain value of φ≈0.09 in the stretched region of the specimen [3]. In order to fulfil increasing environmental regulations, the automotive industry focuses on reducing car body’s weight by using lightweight materials such as aluminium or high strength steel. SCS technology offers the possibility of producing car body panels with high surface quality at a minimum of investment costs. Therefore it is necessary to verify SCS technology for new lightweight sheet metal materials as described in [3]. Because of the material properties of high strength steel it does not make sense to investigate such materials for their use with SCS technology regarding the denting resistance and the part stiffness. However, aluminium is due to lower material properties predestinated for a pre-stretching process to increase such properties. The SCS technology offers a huge potential for pre-stretching aluminium blanks and to produce parts with significant better part quality with regard to part stiffness and dent resistance.

• Improvement Design of Vehicle’s Front Rails for Dynamic Impact

  Chien-Hsun Wu, Chung-Yung Tung, Jaw-Haw Lee - Automotive research & testing center, Caleo C. Tsai - China Motor Corporation

  Frontal collision tests indicate that the energy absorbing components playing the main role of providing protection for the occupants during the crashing processing. The frontal rails are the main components to absorb energy during collision. The position of the spot welding, beads, the cross section and thickness of the frontal rails are significantly facts that affect the energy absorption during impact. This paper is concentrated on improving the energy absorbing efficiency of the vehicle’s front rails during impact and giving better existing space of the passenger compartment after collision by using LS-DYNA. Utilize the improved model to enhance the exiting vehicles and compare the results to the frontal impact test.

• Improvement in predictive capability of smalloverlap crash simulation with emphasis on GISSMO material model, weld rupture and detailed modeling

  M. Parab, J. Sholingar, E. Stahmer, A. B. Sheshadri (FCA)

  CAE tools are one of the best techniques in the auto industry to drive design and help product development with minimal physical tests. Physical tests are very time consuming and expensive which is driving the Auto industry towards virtual simulations to replace physical tests. CAE has become an integral part of product development to accurately predict physical testing and drive design direction. For CAE to accurately predict the physical test, it depends on details captured in the full vehicle model. In the small overlap load case it’s necessary to capture as much detail as possible for components engaged during the impact event. However, capturing too much detail leads to prohibitively large models with excessive computational time. So it is important to understand the load path to decide the critical vehicle components which play a vital role in the crash event. This includes the sheet steel/aluminum stamped parts, aluminum extrusion and also the fasteners and welds. In this paper an attempt is made to revisit the modeling of these critical vehicle components and later confirm the performance with respect to the physical test. The sheet steel/aluminum stamped parts and also the aluminum extrusions are finely meshed and GISSMO material models are implemented to define their rupture. The fasteners (bolts) are modeled using solid elements. Spot welds are modeled as solid nuggets with damage material model MAT_SPOTWELD_DIAMLERCHRYSLER and a simple elegant technique is used to define the aluminum MIG welds. The MIG welds are joining thick Aluminum parts in the cradle. MIG welds are represented by discrete beams with MAT119 material model. The stiffness, loads and rupture displacement parameters are adjusted to component tests and an envelope of rupture is created. This is carried on to the full vehicle as a predictive model and the designs are iterated. All of the above modeling methods and techniques helped to accurately predict velocities, intrusion, wheel kinematics and a good correlation to the physical test was achieved.

• Improvement of Domain Decom­position of LS-DYNA R7 and R8

  M. Makino (Dynapower)

  The domain decomposition is important for get the good performance by mpp version. The calculation of ls-dyna is mainly two parts; element calculation and contact calculation. For element calculation, ls-dyna can distribute the elements equally based on the cost evaluation. Until r6, the cost for solid element was not correctly treated, but r7, the cost of element including the solid element are re-evaluated.

• Improvement of Energy Absorption for the Side Member Using Topography Optimization

  Iku Kosaka - Vanderplaats R&D Inc.

  This paper describes a design system to optimize the non-linear responses computed from LS-DYNA® using various optimization techniques, especially with large-scale (large number of design variables) optimization, and demonstrates the system as it improves the energy absorption for the side member of the vehicle. The proposed design system uses the equivalent static load (ESL) method, which requires the iterative process of non-linear structural analysis (LS-DYNA) and linear structural optimization (Genesis®). Unlike general-purpose optimization software packages, it does not require many analysis calls when a large number of design variables are used to design a structure. Therefore, non-parametric techniques, such as Topology, Topometry, and Topography optimizations, which often require thousands of design variables, can be easily employed. To demonstrate, the side member of the Dodge Neon was optimized to improve its energy absorption using Topography optimization.

• Improvement of Mesh Fusion in LS-DYNA®

  Houfu Fan, Xinhai Zhu, Li Zhang, Yuzhong Xiao, Livermore Software and Technology Corporation

  In this work, mesh fusion in MPP is successfully implemented in LS-DYNA. It has been demonstrated through benchmark examples that MPP mesh fusion can reduce the simulation time (25%) and make sure the accuracy (error within 2%) of the forming process. The result for the corresponding springback analysis is slightly large (error within 10%) and can serve as a rough and quick estimation.

• Improvement of Response Surface Quality for Full Car Frontal Crash Simulations by Suppressing Bifurcation using Statistical Approach

  M. Okamura (JSOL)

  In recent years, it has become increasingly important to take into account dispersion of product quality in automotive industry. Liability and performance has been guaranteed by adding safety margin to its target in the past. However, needs in cost reduction and trade-off of conflicting requirements do not allow manufacturers enough amount of safety margin anymore. A common way to assess robustness of the structure in full car crash is to build response surface and study sensitivity of input scatter to output, and there are many papers available on the issues. However, most of these papers handle linear problems or problems where bending modes are dominant such as side crash simulations. When it comes to frontal or rear crash where buckling mode is dominant, quality of response surfaces tend to be poor, since bifurcations in behavior bring high non-linearity to response surfaces. One measure is to increase the number of simulation runs in order to improve the accuracy of response surface, but as the size of full car simulation models becomes bigger, it is not affordable to run over 100 runs most of times. The fundamental problem is that the response surface is with gaps due to bifurcations so that trying to fit highly non-linear response surface by adding points is not the absolute solution, but to reduce non-linearity of the surface in order to make it easy to fit. In this study, scatter propagation mechanism is visualized based on statistical calculations, and structural design of front structure of an automobile is enhanced in order to suppress bifurcations with help from a statistical analysis software DIFFCRASH. Triggers of bifurcation are located and mechanisms of the bifurcations are studied, and design modifications are made to stabilize the deformation modes. As a result, the roughness of response surface has been reduced, and accuracy of the response surface has been improved.

• Improvement of Satellites Shielding under High Velocity Impact using Advanced SPH Method

  T. Legaud, M. Le Garrec, N. Van Dorsselaer, V. Lapoujade (DynaS+)

  A huge number of debris coming from human activities is currently gravitating around Earth. Their size, their nature, their orbit and their velocity can highly vary, but they all represent an increasing risk of collision and a threat for the current and future space activity [1]. The space actors are looking for solutions in order to limit these risks and to protect the structures from impacts and generation of new debris (spacecrafts conception, limitation of the debris multiplication, waste life stage strategies…).

• Improvement of the Energy Absorption Capacity of an Intercity Coach for Frontal Crash Accidents

  Muhammed E. Cerit, Mehmet A. Guler, Uğur Yolum - TOBB University of Economics and Technology Ankara, Bertan Bayram - TEMSA AR-GE VE TEKNOLOJİ A.Ş.

  According to the accident statistics for buses and coaches, accidents involving frontal crash constitute an important percentage among all bus accidents. In this type of accidents, front body of the bus structure gets severely damaged and this puts the driver and crew in great injury risk. And most of the frontal crash accidents result in death of the bus driver. Because of this, the safety of both the bus driver and the crew should be ensured in the case of frontal crash accidents. Providing the driver’s safety is crucial since the driver is the key person for keeping the control of the bus in the event of an accident so that the safety of the passengers will be ensured. Even though the most of the passive safety standards are related to the safety of the passengers, some international regulations exist for the driver’s safety for heavy vehicles. The European regulation ECE-R29 is arranged to provide the safety of the truck cabin and the driver. This regulation involves a frontal crash pendulum test in which a plate with a specified mass strikes the cabin of the vehicle. A regulation specifically arranged for the safety of bus/coach in the case of frontal crashes does not exist, but some proposals similar to ECE-R29 are being discussed in Working Party on Passive Safety (GRSP) in United Nations Economic Commission for Europe (UNECE). Presumably, a similar regulation for buses will be imposed in the near future. In this paper, frontal crash analysis of the structure of a bus front body was performed according to the ECE-R29 European regulation requirements and the strength of the bus structure was checked whether the safety requirements are satisfied. The nonlinear explicit finite element code LS-DYNA® was used for the crash analyses. The first stage of this study involves the frontal crash analyses of the baseline bus structure without any improvements. At this stage the weak parts of the front end structure of the bus body were determined. In the next stage some improvements were made on the bus structure in order to strengthen the front body. These modifications include the rearrangement of the weak profiles forming the bus front structure. Finally the modified bus structure was compared with the baseline model if the requirements for the driver’s survival space were satisfied according to ECE-R29.

• Improvements and Validation of an Existing LS-DYNA Model of the Knee-Thigh-Hip of a 50th Percentile Male Including Muscles and Ligaments

  Dr. Chiara Silvestri, Mario Mongiardini, Prof. Dr. Malcolm H. Ray - Worcester Polytechnic Institute

  A detailed review of an existing LSDYNA finite element (FE) model of the Knee-Thigh-Hip (KTH) of a 50th percentile male was accomplished. The main scope was to refine some aspects of the model for obtaining a more appropriate and biofidelic tool for injury mechanics investigation of the KTH in frontal car crashes. Detailed reviews of this model were performed with regards to material properties of the bone models used for representation of the pelvis, femur and patella. To investigate bone fracture mechanisms due to impact, the erosion material failure method was abandoned in favor of the adoption of a more realistic detection of failure locations using stress contour plots. Qualitative validations of the pelvis and femur bones of the new model were performed against cadaveric specimen tests conducted at University of Michigan Transportation Research Center. In addition, quantitative validations were performed with use of the Roadside Safety Verification and Validation Program (RSVVP), developed to validate numerical models in roadside safety. The approach for these validations was also different. Earlier work had compared the finite element results to the physical test corridors whereas this work used a direct comparison of each finite element validation simulation to a specific corresponding test. Validation of the bone models were based on comparison of the impact forces from contact between the dashboard and knee region of the KTH model. For each case, force simulation results were in good agreement with experiment outcomes, and FE fracture locations matched failure modes from cadaveric tests. Quantitative results indicate that the test and FE time histories can be considered to be the same, and they therefore represent the same impact event. A new validated dynamic representation of ligaments was adopted for prediction of avulsion ligament injuries in high speed frontal automotive collisions when lower extremities are subjected to high strain rates. FE results from ligament avulsion agreed with test data and injury criteria recommended from literature. A different model of the knee patellar tendon was implemented with use of material SEATBELT and the introduction of slip-rings to constrain the patellar tendon to the biomechanically correct line of action. This refined LSDYNA finite element model of the KTH resulted in a more biofidelic representation of the human KTH and represents a suitable and reliable tool for exploration of KTH fracture mechanisms resulting from frontal vehicle crashes.

• Improvements and Validation of an Existing LS-DYNA Model of the Knee-Thigh-Hip of a 50th Percentile Male Including Muscles and Ligaments

  Dr. Chiara Silvestri, Mario Mongiardini, Prof. Dr. Malcolm H. Ray - Worcester Polytechnic Institute

  A detailed review of an existing LSDYNA finite element (FE) model of the Knee-Thigh-Hip (KTH) of a 50th percentile male was accomplished. The main scope was to refine some aspects of the model for obtaining a more appropriate and biofidelic tool for injury mechanics investigation of the KTH in frontal car crashes. Detailed reviews of this model were performed with regards to material properties of the bone models used for representation of the pelvis, femur and patella. To investigate bone fracture mechanisms due to impact, the erosion material failure method was abandoned in favor of the adoption of a more realistic detection of failure locations using stress contour plots. Qualitative validations of the pelvis and femur bones of the new model were performed against cadaveric specimen tests conducted at University of Michigan Transportation Research Center. In addition, quantitative validations were performed with use of the Roadside Safety Verification and Validation Program (RSVVP), developed to validate numerical models in roadside safety. The approach for these validations was also different. Earlier work had compared the finite element results to the physical test corridors whereas this work used a direct comparison of each finite element validation simulation to a specific corresponding test. Validation of the bone models were based on comparison of the impact forces from contact between the dashboard and knee region of the KTH model. For each case, force simulation results were in good agreement with experiment outcomes, and FE fracture locations matched failure modes from cadaveric tests. Quantitative results indicate that the test and FE time histories can be considered to be the same, and they therefore represent the same impact event. A new validated dynamic representation of ligaments was adopted for prediction of avulsion ligament injuries in high speed frontal automotive collisions when lower extremities are subjected to high strain rates. FE results from ligament avulsion agreed with test data and injury criteria recommended from literature. A different model of the knee patellar tendon was implemented with use of material SEATBELT and the introduction of slip-rings to constrain the patellar tendon to the biomechanically correct line of action. This refined LSDYNA finite element model of the KTH resulted in a more biofidelic representation of the human KTH and represents a suitable and reliable tool for exploration of KTH fracture mechanisms resulting from frontal vehicle crashes.

• Improvements for Implicit Linear Equation Solvers

  Roger Grimes, Bob Lucas, Clement Weisbecker (LSTC)

  Solving large sparse linear systems of equations is often the computational bottleneck for implicit calculations. LSTC is both continuously improving its existing solvers, and continuously looking for new technology. This talk addresses both, describing improvements to the default distributed memory linear solver used by LSTC as well as promising new research. We discuss improvements to the symbolic preprocessing that reduce the occurrences of sparse matrix reordering, a sequential bottleneck and significant Amdahl fraction of the wall clock time for executions with large numbers of processors. Our new approach works for large Implicit models with large numbers of processes when the contact surfaces do not change, or only change slightly. We have also improved the performance of numerical factorization, most significantly with the introduction of a tiled, or two-dimensional distribution of frontal matrices to processors. This improves the computational efficiency of the factorization and also reduces the communication overhead. Finally, we present promising early results of research into using low-rank approximations to substantially decrease both the computational burden and the memory footprint required for sparse matrix factorization.

• Improvements of LS-DYNA ICFD’s two-phase level-set solver

  Z. Solomenko, F. Del Pin, I. Caldichoury, R. Paz, P. Huang

  Numerical simulation of two-phase flows with interface capturing consists in solving a single set of Navier-Stokes equations with variable material properties. Here, we use the level set method for interface capturing [1]. That gives a simple representation of the interface – the level-set scalar field is continuous and allows easy access to geometrical properties at interfaces. That function evolves in time as it is transported by the flow velocity. As the velocity is not uniform in general, the level-set function may need be reinitialized while maintaining the position of interfaces. Numerical methods that are deployed to solve those problems must be chosen meticulously. Depending on the type of flow, advanced numerical techniques must be used to avoid unphysical motion of interfaces. Combinations of numerical methods have been tested on several benchmark tests.

• Improvements to LS- DYNA Implicit Mechanics

  R. Grimes (LSTC)

  LSTC is continually improving the capabilities and performance of Implicit especially in the distributed memory computing environment. This talk will review recent improvements such as (a) removing serial memory restrictions with a new matrix ordering algorithm, (b) reusing the matrix ordering when the matrix structure has not changed from the previous factorization (c) general improvements to performance of the numerical factorization. We will demonstrate these improvements with a series of industrial benchmark problems.

• IMPROVEMENTS TO THE BEVERAGE CAN REDRAW PROCESS USING LSDYNA

  Robert E. Dick - Alcoa Technical Center

  In the United States, in the year 2000, over 100 billion aluminum beverage cans were manufactured. Lightweighting of these aluminum D&I beverage cans has been a continuous process for more than 35 years. Aluminum beverage can "ends" have been made progressively smaller over the years in order to reduce costs. Likewise, cost control efforts have resulted in continuous reduction of the net metal requirements for the can body. To reduce the weight and cost of the "bodies", cans with thinner sidewalls, reduced neck diameters and smaller base diameters have been developed. The reduction in cost has been achieved while maintaining functionality, structural performance, and formability of the can. Today, the gauge of can body stock is as low as 0.0098 inches. With small base diameter cans and a sheet thickness that continues to decrease, the likelihood of profile wrinkling during can forming increases, particularly in the redraw process. Redraw wrinkling is influenced by many factors such as mechanical properties of the aluminum sheet, tooling geometry, contact conditions including the effects of lubrication, and process boundary conditions. These factors are readily handled using the finite element method. A numerical technique for calculating the severity of the redraw wrinkling or wrinkle factor from an LSDYNA finite element analysis is employed. Using this wrinkle factor, and a fully parametric input generator, improvements to the beverage can redraw process are developed.

• Improving Analysis Accuracy By Modeling rivets/bolts As Solids In Sheet Metal Structure

  Ashok L. Ramteke,Ph.D, Prasad B. Nadgouda - Hema Engineering Industries Limited,

  In general, main assembly consists of different sub-assemblies. These sub-assemblies are joined together using rivets/bolts, welds etc. Individual subassembly is often verified for performance using commercial CAE software. To save time, rivet/bolt joints are usually modeled with beam-spider arrangement. Spider represents the rivet/bolt head and a beam connecting two spiders at the centre represents the rivet/bolt diameter. Analyst’s always try to perfect the verification close to practical conditions. In this article, the belt anchorage bracket in seat track assembly is considered for simulation. The performance of rivets joining the belt anchorage bracket to the upper rail of the track is studied in detail. In first simulation, these rivets are modeled with solid hexahedral elements. In the second simulation, these rivets are modeled with beam-spider arrangement. Stresses around the holes, in sheet metal belt anchorage bracket, are studied in both simulations. It has been found, that solid rivet proved to be better option over the beam-spider arrangement. The simulation is carried out as quasi static analysis in Ls-Dyna 971.

• Improving Analysis Accuracy By Modeling rivets/bolts As Solids In Sheet Metal Structure

  Ashok L. Ramteke,Ph.D, Prasad B. Nadgouda - Hema Engineering Industries Limited,

  In general, main assembly consists of different sub-assemblies. These sub-assemblies are joined together using rivets/bolts, welds etc. Individual subassembly is often verified for performance using commercial CAE software. To save time, rivet/bolt joints are usually modeled with beam-spider arrangement. Spider represents the rivet/bolt head and a beam connecting two spiders at the centre represents the rivet/bolt diameter. Analyst’s always try to perfect the verification close to practical conditions. In this article, the belt anchorage bracket in seat track assembly is considered for simulation. The performance of rivets joining the belt anchorage bracket to the upper rail of the track is studied in detail. In first simulation, these rivets are modeled with solid hexahedral elements. In the second simulation, these rivets are modeled with beam-spider arrangement. Stresses around the holes, in sheet metal belt anchorage bracket, are studied in both simulations. It has been found, that solid rivet proved to be better option over the beam-spider arrangement. The simulation is carried out as quasi static analysis in Ls-Dyna 971.

• Improving Crash Analysis by Increasing Throughput of Large-Scale Simulations

  Dale I. Dunlap, Shawn Freeman - Platform Computing

  Numerical simulation is an important tool used by engineers to design and develop safe automobiles. As engineers study larger and more complex models, demand for computational throughput increases. Grids allow a company to utilize its existing hardware investment to build a cost-effective platform for simulating automotive crash testing. This paper will discuss how grid technology can substantially increase computational throughput of large-scale parallel simulations without having to upgrade the existing compute infrastructure. This leads to significant payback since customers can complete more work, while also deferring capital and operational costs.

• Improving Crash Analysis Through the Estimation of Residual Strains Brought About by Forming Metal

  William Broene - Brown Corporation of America

  This paper describes a method that can be used to estimate the residual strains from the forming of sheet metal without running forming simulations. For a first-order crash analysis, using estimated residual strains rather than the strains reported from several forming simulations increases the speed of the design process. The method estimates residual forming strains from the part geometry itself and assumes that the part was formed from a planar sheet of metal. The importance of considering the forming history of a part is demonstrated by comparing crash analysis results with and without the consideration of these residual strains. Along with this, physical test results will be compared of a part as formed and an identical part which was heat treated to relieve some of the cold working strains. Once the importance of considering forming history has been established, an alternative method of estimating residual strains will be examined. Crash analysis results using forming simulation residual stresses and strains will be compared to analysis results using estimated strains from the alternative method. Finally the scope of application of this strain estimation method will be discussed.

• Improving LSTC’s Mulitfrontal Linear Equation Solver

  R. Lucas, R. Grimes, F. Rouet, C. Weisbecker (LSTC)

  Solving large sparse linear systems of equations is often the computational bottleneck for implicit calculations. LSTC is continuously improving its existing solvers, as well as looking for new technology. This talk describes improvements to the default multifrontal distributed memory linear solver used by LSTC. Changes in semiconductor technology have transformed microprocessors and their memories. In collaboration with Intel, LSTC has adapted by reducing memory movement and restructuring arithmetic kernels to increase the use of LAPACK kernels. Meanwhile, solid state persistent storage technology dramatically improves the performance of out-of-core computations. To address the ever growing size and complexity of the models being created by LS-DYNA users, LSTC is working with Cray to redesign its sparse matrix factorization kernels to solve hundreds of millions of equations using tens of thousands of cores. Finally, to address the exponential scaling of storage and operations associated with ever larger models, LSTC is once again exploring low-rank approximation technology.

• Improving Performance of LS-DYNA® Crash Simulation with Large Deformation by Modifying Domain Decomposition

  Shota Yamada (Fujitsu Limited)

  In modern high performance computing era, parallel computing has been a trend to improve the speed of computation. In the past we have found that just simply increasing the number of computing parallelism would not guarantee to achieve better performance especially when simulating large deformation using hundreds or more number of parallel processors. Through our past experience, to improve the computational performance, we had found it was necessary to tackle on the issue of load unbalance of calculation cost among processors and to seek for better strategy in domain decomposition. In general, calculation cost increases with respect to the extent of deformation. To reduce the unbalance of calculation cost among processors, ideally we would like to decompose domain to subdomains with same extent of deformation on all processors. Even it is possible, it would be difficult to achieve such ideal decomposition for the cases with only local deformation occurred in crash simulation. Therefore we come up with a new enhanced method to decompose the model by distributing calculation cost more uniformly in crash simulation. In this paper, I will reveal this enhanced method, present the results of improved performance of this method using several models of crash simulation, and discuss the efficiency of this method.

• Improving Productivity by Immersion and Interaction – A New Approach in CAE

  Dr. A. Rößler - ICIDO

• Improving Robustness of Chevrolet Silverado with Exemplary Design Adaptations Based on Identified Scatter Sources

  D. Borsotto (Sidact)

  The investigations described here are related to the unstable behavior of crash-simulations due to minor changes in the model. As a consequence the received simulation results become in some way unpredictable, whereby the causes can be various: e.g. modeling failure, contact issues, numerical instabilities, physical instabilities, etc

• IMPROVING THE IMPACT RESISTANCE OF MASONRY PARAPETS

  G. Beattie, T.C.K. Molyneaux - University of Liverpool, M.Gilbert, B.Hobbs, S.Burnett, P. Newton - University of Sheffield, D.A.Gration - Arup Advanced Technology Group

  There are over 60000 masonry bridge parapets in the UK. Whereas steel and concrete parapets are well covered by design standards masonry parapets are not. Initially LS-DYNA was used to model vehicle impacts on various forms of masonry parapet. The results were encouraging, with good qualitative agreement between tests and analysis. The same finite element modelling strategy was subsequently used to help develop a guide for assessment (County Surveyors’ Society Guidance Note, 1995) and a new British Standard (BS 6779 pt 4, 1999). The findings of the initial study demonstrated that unreinforced masonry could perform reasonably well in preventing vehicle penetration and controlling the rebound of impacting vehicles. However the work highlighted two areas that required additional study: (i) in critical situations requiring improved impact resistance, advice on alternative strengthening methods or new build options was needed; (ii) the discrete analysis approach adopted, using LS-DYNA tied interface type 9, required use of unrealistic failure parameters in order to prevent a premature (brittle) failure. The current project is addressing these two issues by the use of both physical tests and finite element analysis. The test work involves a range of small and medium scale tests that provide data for the numerical work. These tests address the issue of dynamic enhancement of the shear and tensile strength of masonry. In addition, the effects of fracture energy and dilatancy under high strain rates are being considered. Test methods have also been developed to evaluate the interaction between the masonry and reinforcement under varying strain rates. Full-scale tests are also being used to both provide analytical data in the early stages of the project and to validate the use of LS-DYNA as a predictive tool in the latter stages of the project. The fullscale test walls range from approximately 9m to 20m in length. In the numerical models the existing LS-DYNA interfaces are being modified to incorporate the effects of fracture energy and dilatancy. Early results are promising, allowing realistic material properties to be used and seeming to explain the apparent high strain rate sensitivity of the measured data. Strategies for modelling reinforcement in a masonry wall are also being developed. Related work where LS-DYNA is being used to model masonry arch bridges is also summarised within this paper.

• Improving the Precision of Discrete Element Simulations through Calibration Models

  Adrian Jensen, George Laird (Predictive Engineering), Kirk Fraser (Predictive Engineering, University of Quebec at Chicoutimi)

  The Discrete Element Method (DEM) is fast becoming the numerical method of choice for modelling the flow of granular material. Mining, agriculture and food handling industries, among many others, have been turning their attention towards this powerful analysis technique. In this paper, we present three simple calibration modeling tactics that should be the starting point for every DEM simulation of dry and semi-dry granular material. The three tests are designed to be as simple as possible in order to minimize the run time of the test simulations. The tests are developed to be run in a specific order, providing a sequential calibration procedure that does not involve multiple unknown variables in each test. Other standard testing methods are briefly discussed, such as the rotating drum and the shear cell (Jenike) tests. The complexity of these tests does not lend itself well to initial numerical model calibration as each test involves many unknown variables. However, they are mentioned as an extension of the three basic test models. The paper will help analysts to increase the precision and validity of their discrete element modelling work.

• Improving the Prediction of LS-DYNA Calculations with Rhodia Data and Digimat

  Cécile DEMAIN - Lyon Research and Technology Center

• Improving the Roadside Safety with Computational Simulations

  Matej Vesenjak, Zoran Ren - University of Maribor

  The road restraint systems on public streets are used to prevent a vehicle to veer off the road or its breakthrough to the opposite side of the road. The road restraint systems designed according to the EN 1317 standard are intended to provide certifiable levels of vehicle containment, to redirect errant vehicles and to provide guidance for pedestrians and other road users. Its proper design is therefore crucially important for safety of all road users. Practical observations of installed systems indicate that the current design of road restraint system is far too stiff. This results in unacceptable decelerations during the vehicle impact. The global stiffness of the road restraint system is largely attributed to the design of the distance spacer in the initial phase of an impact. The purpose of this research is to evaluate several new designs of a distance spacer with increased strain energy absorption due to controlled deformation during the vehicle impact. The impact severity and stiffness of various designs have been evaluated with dynamic nonlinear elasto-plastic analysis of a three-dimensional road restraint system within the framework of the finite element method with LS-DYNA. The computational analyses prove that the currently used distance spacer is indeed too stiff and that new designs assure controllable elasto-plastic deformation and crash energy absorption which in turn decreases the decelerations of an impact vehicle and consequently increases the safety of vehicle passengers.

• imulation of the flow around a Vertical Axis Wind Turbine : LS-DYNA v980

  Iñaki CALDICHOURY, Vincent LAPOUJADE - Alliance Services Plus, Hervé LE SOURNE, Abdelhaq ABDELQARI - Institut Catholique d’Arts et Métiers, Facundo DEL PIN - LSTC

  The future 980 version of LS-DYNA® will include Computational Fluid Dynamics (CFD) solvers. The main objective of these new solvers will be to perform fluid structure interactions by directly solving the Navier-Stokes equations and by using any LS-DYNA® Lagrangian model for the solid part. In the process of evaluating the new possibilities offered by these new solvers, in particular concerning fluid structure interaction, AS+ has worked in partnership with both industrial and academic clients on the case of a vertical axe wind turbine which was used in the French around the world boat race “Vendée Globe”. The final objective of these simulations is to test various turbine shapes and airfoils in order to determine which one would offer the best aerodynamic behavior without any compromise to its structural behavior. Tests were therefore first conducted on static or oscillating airfoils. Then, 2D simulations of various turbine shapes were performed before aiming for the complete 3D simulation of the problem. This paper aims to highlight the main features of the new incompressible solver by presenting the results obtained on one of the first industrial cases that use the new v980 version.

• IN BORE BEHAVIOUR OF LARGE CALIBRE ARMOUR PIERCING FIN STABILISED DISCARDING SABOT PROJECTILES.

  N.Eches, N.Paugain, C. Doffémont - Giat Industries

  The efficiency of large calibre armour piercing fin stabilised discarding sabot projectiles (APFDS) is primarily linked to their terminal ballistics performances. But other parameters, such as its accuracy and its yaw at the impact have also a large influence on the performance. These two parameters magnitude, as well as the survivability of the projectile during the launch phase are greatly affected by the interaction between the projectile and the gun, also known as the “balloting”. Nowadays, the accurate description of the rod free flight has been made possible thanks to Computational Fluid Dynamics calculations, allowing to predict the flight quality or the retardation, and back calculation of initial disturbances of an unexpectedly odd shot. But this situation is not true for the early moments of the firing sequence, i.e. the projectile inbore travel and the sabot separation. For the latter, a long way to go remains. But, in the field of projectiles in-bore behaviour, a lot of works have been performed, using different numerical methods, which allowed scientists to make significant progress. This paper describes some of the works performed in the Giat Industries Weapon and Ammunition Systems Division (DSAM), whose purpose was to understand how the interactions between the weapon and the projectile could affect its mechanical behaviour and its muzzle exit conditions.

• In Core Adaptivity

  Brian Wainscott, Houfu Fan, LSTC

  Adaptivity is almost universally used in metal forming applications. As useful as it is, there are certain inefficiencies in its execution which are a result of the way in which it was implemented. The current approach requires a significant amount of I/O and code serialization. A new method is being developed in MPPDYNA which not only performs the adaptivity in parallel, but without exiting the solution loop. The current status of this work is presented.

• Incompressible CFD Results Using LS-DYNA. For High Reynolds Number Flow Around Bluff Bodies

  I. CALDICHOURY, F. DEL PIN - LSTC, V. LAPOUJADE - AS+

  This report will provide some insight on the new incompressible CFD solver that will be available in version 980 of LS-DYNA. Several test cases were performed by AS+ in order to evaluate the capabilities of these new solvers. These studies were conducted in cooperation with LSTC’s CFD developers. Among the various test cases, the airflow over the Ahmed body, a simplified car model will be presented. The flow around this body reproduces the basic aerodynamic features of cars on a well defined basic geometry in order to study the complex interactions associated with vortex wakes and boundary layer separation/reattachment zones. Results were compared to experimental data extracted from reference papers. The results shown here are all part of the global validation process of the incompressible CFD solver.

• Incompressible Smoothed Particle Galerkin (ISPG) Method for an Efficient Simulation of Surface Tension and Wall Adhesion Effects in the 3D Reflow Soldering Process

  Xiaofei Pan, C. T. Wu, Wei Hu (Livermore Software Technology (LST), an Ansys Company)

  A new numerical method in LS-DYNA®, the incompressible smoothed particle Galerkin (ISPG) method, is developed for the simulation of shape evaluation of solder joints in electronic equipment during the reflow process. The ISPG method is aiming to suppress key numerical instabilities observed in the simulation of incompressible free surface fluid flow using strong form Lagrangian particle methods such as SPH. In ISPG method, a momentum-consistent smoothing algorithm is utilized to offer the desired numerical stability associated with the velocity field in the fluid particle integration scheme. To stabilize the pressure field in Navier-Stokes equations, a second-order generalized rotational incremental pressure-correction scheme is developed for the incompressible fluid flows. To simulate the shape evolution of solder joints during the reflow process, a numerical procedure considering the surface tension and wall adhesion effects is introduced. Several numerical examples are studied to demonstrate the accuracy and the efficiency of the new method.

• Inconel 713 and TiAl turbine blade impact test validation with LS-Dyna, including Inconel 718 casing and failure models

  I. Catalina, K. Manzanera (ITP Aero)

  Motivated by the necessity of validating new materials for future turbines, a set of Blade Crush Tests have been performed with Inconel 713 blades, TiAl blades, Inconel 718 casing material and steel plates. The objective of these tests is to study separately the deformation of a blade during a containment event (configuration 1 tests), and the damage of the casing caused by the impact of different blades (configuration 2 tests). The results of these tests are validated with LS-Dyna analysis, providing a reliable tool for predicting the containment capability of the casings and the out of balance progression in a blade off event. This will allow to assess the containment capability of future designs without the need of large and very costly test campaigns or service experience.

• Incorporation of Damage and Failure Into an Orthotropic Elasto-Plastic Three-Dimensional Model with Tabulated Input Suitable for Use in Composite Impact Problems

  Robert K. Goldberg and Kelly S. Carney (NASA Glenn Research Center), Paul Du Bois (George Mason University), Canio Hoffarth, Bilal Khaled and Subramaniam Rajan (Arizona State University), Gunther Blankenhorn (LSTC)

  A material model which incorporates several key capabilities which have been identified by the aerospace community as lacking in the composite impact models currently available in LS-DYNA ® is under development. In particular, the material model, which is being implemented as MAT 213 into a tailored version of LS-DYNA being jointly developed by the FAA and NASA, incorporates both plasticity and damage within the material model, utilizes experimentally based tabulated input to define the evolution of plasticity and damage as opposed to specifying discrete input parameters (such as modulus and strength), and is able to analyze the response of composites composed with a variety of fiber architectures. The plasticity portion of the orthotropic, three-dimensional, macroscopic composite constitutive model is based on an extension of the Tsai-Wu composite failure model into a generalized yield function with a non-associative flow rule. The capability to account for the rate and temperature dependent deformation response of composites has also been incorporated into the material model. For the damage model, a strain equivalent formulation is utilized to allow for the uncoupling of the deformation and damage analyses. In the damage model, a diagonal damage tensor is defined to account for the directionally dependent variation of damage. However, in composites it has been found that loading in one direction can lead to damage in multiple coordinate directions. To account for this phenomena, the terms in the damage matrix are semi-coupled such that the damage in a particular coordinate direction is a function of the stresses and plastic strains in all of the coordinate directions. The onset of material failure, and thus element deletion, is being developed to be a function of the stresses and plastic strains in the various coordinate directions. Systematic procedures are being developed to generate the required input parameters based on the results of experimental tests.

• Incorporation of Inconel-718 material test data into material model input parameters for *MAT_224

  Stefano Dolci1, Kelly Carney1, Leyu Wang, Cing-Dao Kan (George Mason University), Paul Du Bois (Consulting Engineer, Northville)

  A research team from George Mason University, Ohio State University, NASA and FAA has developed material data and analytical modeling that allows for precise input of material data into LS-DYNA ® using tabulation and the *MAT_224 material model. The input parameters of this model are based on data from many experimental coupon tests including tension, compression, impact, shear and biaxial stress states. The material model also includes temperature and strain rate effects. This research effort involves the incorporation of the Inconel-718 material test data into the material model. This requires the development and validation of a set of material constants for this particular alloy, utilizing the tabulated input method of material model *MAT_224 in LS-DYNA with consideration given to strain rate and temperature. Alloy Inconel-718 is a precipitation hardenable nickel-based alloy designed to display exceptionally high yield, tensile and creep-rupture properties at temperatures up to 1300°F. The sluggish age-hardening response of alloy 718 permits annealing and welding without spontaneous hardening during heating and cooling. This alloy has been used for jet engine and high-speed airframe parts such as wheels, buckets, spacers, and high temperature bolts and fasteners. *MAT_224 is an elastic-plastic material with arbitrary stress versus strain curve(s) and arbitrary strain rate dependency, all of which can be defined by the user. Thermo-mechanical and comprehensive plastic failure criterion can also be defined for the material. This requires a process of test data reduction, stability checks, and smoothness checks to insure the model input can reliably produce repeatable results. Desired curves are smooth and convex in the plastic region of the stress strain curves.

• Incorporation of Material Model into LS-DYNA Implicit to Model the Shear Behavior of Uncured Woven-Fabric Composite Materials

  Jennifer L. Gorczyca, James A. Sherwood, Darin S. Lussier, Julie Chen - University of Massachusetts Lowell

  A shear-frame FE model for use in the LS-DYNA implicit code was created to predict the forming behavior of an uncured woven-fabric composite material. This FE model contains fully integrated shell elements and beam elements. A material model developed by McBride and Chen for plain-weave woven composite materials and later refined by Bulusu and Chen to account for different fabric weaves was incorporated into LS-DYNA implicit to model the behavior of a 40-60 glass-polypropylene satin-weave fabric as the fabric deformed in a shear-frame experiment. The normalized force-displacement results from the FE model were compared to the experimental results.

• Increasing CAE Productivity – Airbag Model Verification using Visual-Environment

  N. Möwe (iSi Automotive), M. Sommer, A. Gittens (ESI)

  Technological advancement, customer expectations and globalization have increased the need for higher productivity in any industry. In general, productivity is a measure of performance or output. There are various proven methods/techniques to increase and improve productivity. One such proven method is through adoption of Automation, the technology by which a process or procedure is performed with minimum human assistance and interaction.

• Increasing Efficiency of the Design Process with an Isogeometric Analysis Plugin for Siemens NX by Analyzing the CAD Model Directly

  M. Breitenberger, B. Philipp, R. Wüchner, K.-U. Bletzinger (Technical University Munich), S. Hartmann, A. Haufe (DYNAmore)

  The bottleneck for today’s integrated CAD and CAE tools or for the design-through-analysis process in general is the fact that for each product at least two different geometry representations are used. On the one hand side there is the CAD model and on the other hand side there is the finite element mesh, both representing the same object. The conversion between CAD model and FE model are named meshing and CAD reparameterization, respectively. These operations are error prone, time consuming and cannot fully be automatized.

• Increasing Initial Internal Energy of Air Elements near Explosive for Fluid-Structure Models of a Steel Plate Subjected to Non-contact Explosion

  Wen-Chih Li, Wen-Feng Yu, Ding-Shing Cheng - National Defense University

  This study was to simulate a steel plate subjected to non-contact explosion by using Arbitrary Lagrangian-Eulerian (ALE) algorithm of the LS-DYNA software. A 3-D Fluid-Structure interaction model was considered. The numerical result would be compared with S.D. Boyd’s experiment, which 250g Pentolite explosive detonated above a 5 mm thick steel plate. The Eulerian mesh for explosive and air and the Lagrangian mesh for steel plate and its supporting system were coupled together with overlap. The JWL equation of state and the linear polynomial equation of state were used for explosive and air respectively. A bilinear stress-strain relationship was assumed for the steel plate which was modeled with shell elements. By increasing initial internal energy of air elements near explosive with a temperature of 3000K, the maximum displacement of the midpoint of the steel plate from the ALE model for explosive with a standoff distance of 50 cm was improved from an error of -46.7% to 15.3% after compared with S. D. Boyd’s experiment in 2000. Besides, the maximum displacement for the case of explosive with a standoff distance of 25 cm can have an significant improvement with only 0.5% error.

• Increasing LS-DYNA® Productivity on SGI Systems: A Step-by-Step Approach

  Olivier Schreiber, Tony DeVarco, Scott Shaw, Aaron Altman (SGI)

  SGI delivers an unified compute, storage and remote visualization solution to our manufacturing customers that reduces overall system management requirements and costs . LSTC has now integrated Explicit, Implicit solver technologies into a single hybrid code base allowing seamless switching from large time steps transient dynamics to linear statics and normal modes analysis. There are multiple computer architectures available from SGI to run LS-DYNA. They can all run LSTC solvers using Shared Memory Parallelism (SMP), Distributed Memory Parallelism (DMP) and their combination (Hybrid Mode) as supported by LS-DYNA. Because computer resources requirements are different for Explicit and Implicit solvers, this paper will study how advanced SGI computer systems, ranging from multi-node Distributed Memory Processor clusters to Shared Memory Processor servers address the computer resources used and what tradeoffs are involved. This paper will also outline the SGI hardware and software components for running LS-PrePost® via SGI VizServer with NICE Software. CAE engineers, at the departmental level, can now allow multiple remote users create, collaborate, test, optimize, and verify new complex LS-DYNA simulations in a single system and without moving their data.

• Increasing the Scale of LS-DYNA® Implicit Analysis

  Jef Dawson, Ting-Ting Zhu, Cray;, Cleve Ashcraft, Roger Grimes, Robert Lucas, Francois-Henry Rouet, Livermore Software Technology Corporation;, Erman Guleryuz, Seid Koric, National Center for Supercomputing Applications;, James Ong, Rolls-Royce

  Cray, LSTC, NCSA, and Rolls-Royce formed a partnership to explore the future of implicit computations as the scale of both finite element models and the systems they run on increase. Rolls-Royce created a family of dummy engine models, using solid elements, with as many as 200,000,000 degrees of freedom. NCSA ran these with specialized LS-DYNA variants, generated by Cray, on their Blue Waters machine, a hybrid Cray XE/XK system with 360,000 AMD cores. Processing and memory bottlenecks revealed themselves as the number of processors increased by an order-of-magnitude beyond that familiar to today’s developers and users, and LSTC made improvements to LS-DYNA.

• Incremental Damage Model for Fatigue Life Assessment in Complete Machinery Simulation

  Marcus Lilja, Jesper Karlsson, Anders Jonsson, Daniel Hilding (DYNAmore Nordic AB), Stefan B. Lindström, Daniel Leidermark, Peter Schmidt (Linköping University)

  In CAE today a transition towards “complete machinery simulation”, away from the traditional component or sub-assembly simulation, is seen. The complete, assembled and pre-loaded machine is simulated with real loads and boundary conditions which minimizes the risk of errors in the boundary conditions and loading. The longer simulation time is mitigated by the reduction in the number of load cases needed and that a single simulation yields the results for all components. This “complete machinery simulation”-approach is not new, e.g. in the automotive industry LS-DYNA® has been used for realistic simulations for many years and this approach has now reached other industry sectors as well. When developing e.g. heavy industrial equipment, static strength is not a common failure mode, but fatigue is. Fatigue life estimation of a product is crucial and since fatigue tests are both expensive and time-consuming there is a need for accurate fatigue simulation methods. Fatigue analysis within the CAE-process is commonly based on the rainflow count method for cycle counting and the Palmgren-Miner’s linear damage accumulation model. The fatigue life prediction is performed on the result history from a previous analysis and is dependent on the output frequency so that all peaks and valleys of the result variation are identified. This method is widely used and is well-suited for most of the common fatigue scenarios today. However, when using complete machinery simulation, shortcomings in the above method have been identified to be caused by the combination of very large models, high frequency output, and non-proportional loading. This tends to result in a great amount of data for the subsequent fatigue analysis. The amount of data makes post processing and fatigue analysis cumbersome and since development is an iterative process, disk space may become a critical factor. This paper presents an implementation of the incremental fatigue model of Ottosen and co-workers [Int. J. Fatigue, 30:996-1006 (2008)] as a user-material for LS-DYNA. The model offers a uniform framework for multiaxial, non-proportional and non-cyclic loading. With this model, the fatigue assessment is made on the element level during the simulation. The model enhances performance in terms of faster integration, less data storage, and easier usage. A comparison of the fatigue life predicted using the new method to the standard rainflow count method for selected grades of steel and aluminum is presented.

• Incremental Forming Simulation of Dimples for Solar Mirror Supports using Isogeometric Analysis

  Wade Evans, Johannes Pottas, Lukas Leidinger, Amit Nair, Fabian Knieps, Benjamin Liebscher, John Holmes, Joe Coventry

  Heliostats are concentrating mirrors which track the sun to direct light onto a receiver in concentrating solar power (CSP) systems. Heliostat cost and performance are major contributors to the capital cost of CSP systems and their levelised cost of energy. For this reason, several existing heliostat mirror facet designs utilise low-cost stamped supports which are laminated to glass mirrors to impart stiffness and maintain shape accuracy of the optical surface, whether curved or flat.

• Inductive and Radiofrequency (RF) heating in LS-DYNA for medical and other industrial applications

  Iñaki Çaldichoury, Pierre L’Eplattenier

  Inductive and radiofrequency heating both rely on an electromagnetic power source to generate heat. However, they are based on different frequency scales that trigger different electromagnetic behavior and make some terms predominant over others. Inductive heating can be viewed as a “contactless” form of heating where a current source (typically a copper coil) with a frequency in the range of 𝐾𝐾𝐾𝐾𝐾𝐾 or MHz approaches another conductor thus triggering induced currents (Eddy currents) in nearby conductors which can generate heat, depending on the material’s properties (resistivity, permeability). In this paper, radiofrequency heating can be viewed as an extension of traditional Resistive heating where an electrode is plugged between two ends of a specific material. Contrary to resistive heating, the material’s electrical conductivity is usually very low, or the material can be an insulator, but the input source is in a high frequency range (𝐺𝐺𝐾𝐾𝐾𝐾 or higher) which triggers molecular displacements that generate heat via friction. This dielectric heat source term becomes the dominant factor rather than the Ohmic losses term.

• Inelastic Transversely Isotropic Constitutive Model for High Performance Polymer Fibers

  Subramani Sockalingam, Michael Keefe, John W. Gillespie Jr. (University of Delaware)

  High performance polymer fibers such as Kevlar, Spectra and Dyneema are widely used in ballistic impact applications. Under transverse compression at finite strains these fibers exhibit nonlinear inelastic behavior. The role of transverse compression during ballistic impact is not very well understood. In this work we implement a transversely isotropic inelastic constitutive model as a user defined material model (UMAT) in LS-DYNA®. A plasticity approach is used to model the material nonlinearity and a pseudo-elastic approach for the large residual strains in the transverse fiber plane. Based on the experimental results, the material nonlinearity and inelasticity are decoupled from the fiber direction. The UMAT predictions for a single Kevlar KM2 fiber under transverse compression are compared to the experimental load deflection under monotonic and cyclic loading.

• Influence of Contact Parameters on Short-Event Crash Simulation Results

  Nick Kalargeros, Jack Perry, Antonio Peralta, Lee Pearce (Jaguar Land Rover Limited)

  The aim of a vehicle crash simulation is to characterise and quantify the performance of specific regions in terms of energy dissipation, distribution and intensity. Such detailed understanding of the crash event will enable the analysis and prediction of occupant and / or pedestrian injuries. To achieve this, an interacting chain of individual components and systems need to be studied in terms of its energy management and absorption capacity. A study should consider the unique contact interactions between the key components and systems involved. More so, these unique contact interactions have to be numerically captured and formulated in a manner that is faithful to the actual physical event. The premise of this paper is to report initial findings from a study of the sensitivity of short crash events to different contact parameters and conditions. The relevant CAE modelling representations which lead to better agreement between virtual and physical results are explained. The aim is to increase the predictive capability not only of the nominal accuracy of the CAE predictions, but also to fully capture the chronological sequence of events and behaviours during the real short-event crash simulation.

• Influence of Discretisation on Stiffness and Failure Prediction in Crashworthiness Simulation of Automotive High Pressure Die Cast Components

  Felix Brenner, Helmut Gese, Gernot Oberhofer (MATFEM Partnerschaft Dr. Gese & Oberhofer), Michael Buckley (Jaguar Land Rover Limited)

  Castings are widely used as part of the car chassis in automobile manufacture because of their light weight and the flexibility of the design process. Due to the comparable low ductility of castings, it is essential for crash simulations to gain dependable analyses. However, modelling casting parts correctly for finite element analyses is an issue for several reasons. In order to represent the elastoplastic stiffness correctly and thus to obtain reliable failure predictions, an accurate prediction of plastic strains and the corresponding stress states is required. To meet these conditions an adequate material and failure model is needed. Besides the characterisation and modelling of the material, the geometric discretisation is a trade-off between computational costs, meshing effort and the quality of the results that can be achieved in simulations. Typically, no general guidance is provided on the appropriate element formulation or the impact this choice may have on the results. Lastly, in industrial environments economic competition usually does not allow for extensive basic research. Conservative methodologies in development and simulation of castings are the norm since new methods carry the risk of failure. Thus avenues of improving accuracy and reducing costs of simulations remain to be explored.

• Influence of Element Formulation on the Axial Crushing of Thin-walled Dual-phase Steel Square Sections

  Venkatapathi Tarigopula, Magnus Langseth, Odd Sture Hopperstad - Norwegian University of Science and Technology

  This paper presents a systematic numerical investigation of the influence of element formulation on the force- deformation characteristics and crush behaviour of thin-walled dual-phase steel square tubes subjected to axial loading. Influence of shell and volume elements were verified on the crush behaviour. Finite element models square sections were created and analysed using the non-linear explicit finite element code LS-DYNA®. Parameters of interest were the energy absorption, peak crush load capacity, and the crush behaviour. The strain-rate effect has been considered for the dynamic simulations. Even though the initial peak load from numerical analyses differs significantly from the tests, the mean force does not deviate greatly whatever may be the element formulation. Both shell and brick elements predicted the experimental responses reasonably well. However, the element aspect ratio in volume element simulations seems to play a role in accurately capturing the local bending response when subjected to axial compressive load.

• Influence of HE shape on blast profile

  J. Mespoulet, F. Plassard, P. Hereil - Thiot-Ingenierie, A. Lefrançois - CEA

  This paper is concerned by the effect of HE geometry on the shape of the blast wave. The aim of this work is to increase the knowledge on pressure profile generated by blast wave so as to optimize the design of explosion chambers. These facilities are commonly designed for spherical HE but most of the customer charges have other geometry (line, plate, cylinder ...). Numerical simulations performed with Multi Materials Arbitrary Eulerian solver in LSDYNA were used to simulate hemispherical and rectangular shape HE events detonated on the ground. Pressure records in front of the charge (reflected pressure) and on lateral positions at different locations (incident pressure) are compared to experiments performed at CEA / Gramat. High speed video has also been used to visualize the shape of the fireball and the shock wave in air. It is confirmed numerically that the shape of explosive generates different shape of blast wave and so will change the way of designing new chambers.

• INFLUENCE OF MANUFACTURING PROCESSES ON THE PERFORMANCE OF VEHICLES IN FRONTAL CRASH

  Dr.-Ing. Horst Lanzerath, Dr.-Ing. Omar Ghouati, Dr.-Ing. Jürgen Wesemann - Ford Forschungszentrum, Dr.-Ing. Robert Schilling - Ford-Werke AG

  The importance of new material applications for improved passive vehicle safety is increasing. Automotive companies are using CAE methods to predict the crash behaviour of cars and to select materials for body structures, which fulfill the safety targets. The quality of crash simulations heavily depends on the material models used for these investigations. In this paper results of research projects on the application of new high strength steel sheet metal in side rail structures are presented. The simulation models used in these studies are described and their importance for Finite Element applications in passive safety is underlined.

• Influence of Pre-Stressed Parts in Dummy Modeling - Simple Considerations

  Ulrich Franz, Peter Schuster, Sebastian Stahlschmidt - DYNAmore GmbH

  New regulations and consumer tests for passive safety in passenger cars have increased the de- mand on accurate models for occupant analysis. Thus, effects that have been neglected or mod- eled rather coarsely in recent occupant models might necessitate a more detailed modeling in order to capture the dummy behavior sufficiently accurate. This paper contributes to the discussion of the importance and the modeling techniques of pre- stressed parts in dummy models for occupant analysis. The authors present solutions provided by LS-DYNA to handle the pre-stressed parts like mapping, pre-simulation, or implicit time-step- ping for positioning. Finally, the paper discusses sources of pre-stress in different parts of side impact dummies (SID), Hybrid III adult and child dummies. With simple examples the influence of the pre-stress is estimated.

• Influence of Selection Criterion on the RBF Topology Selection for Crashworthiness Optimization

  Tushar Goel, Nielen Stander - Livermore Software Technology Corporation

  Meta-models are frequently used to offset high computational cost of crashworthiness optimization problems. Radial basis function based meta-models are gaining popularity among various meta-modeling techniques due to their ability to approximate non-linear responses with relatively low fitting cost. However, the performance of RBF networks is very sensitive to the choice of topology. In this paper, the influence of three selection criteria namely, PRESS, pointwise PRESS error ratio, and estimated variance of noise, over network topology is studied. The results are demonstrated for a few analytical functions and a crashworthiness simulation of a full NHTSA vehicle problem. The results showed that the PRESS-based method was the most reliable method to select network topology.

• Influence of Side Windows Type on Occupants’ Injury Response in the Cutaway Bus Rollover Analyses

  Grzegorz Dolzyk, MohammadReza Seyedi, Sungmoon Jung, Jerzy Wekezer, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046

  In the rollover crash scenarios, occupants are often subjected to impact with interior parts of the bus, especially side windows which play the main role in ejection protection. In this study, we investigated the influence of the window’s glass type and their modeling techniques into occupants’ response during the rollover experiment. Rollover experiment of the cutaway bus was conducted in compliance with ECE R66, which is also known as a tilt table test. Two-point Hybrid III 50th male Anthropomorphic Test Device (ATD) was seated next to the window, on the impact side. Full scale numerical analyses were conducted with nonlinear explicit code LS-DYNA®. In the cutaway buses, a tempered glass is used commonly for the side windows. The effect of potential replacement with laminated glass was analyzed and its role in the ejection protection. Two common modelling techniques were used to represent a laminated glass, layered single-shell and double-shell model with coincident nodes. Also, the influence of yield stress was investigated, for both, laminated and tempered glass models. Head and chest accelerations and axial neck forces of the two-point belted ATD were presented and relevant injury criteria were compared. Results show the importance of using the laminated glass for the partial and full ejection prevention. Likewise, glass properties and modelling techniques can be meaningful in the validation process.

• Influence of Solidification-Dependent Microstructure on Subsequent Metal Forming Operations

  J. Kronsteiner, S. Hovden, S. Jäger (LKR), E. Kabliman (TUM)

  Conventional metal deformation simulations which include microstructure evolution would not consider any initial spatial variations but assume a uniform microstructure. In metal manufacturing, the liquid phase during casting and its subsequent solidification play major roles in characterizing the material properties (both micro- and macroscopic). Physics-based material models allow to simulate microstructural effects based on measurable microstructural properties. However, some parameters such as the grain size vary considerably within the manufactured part geometry depending on the processing conditions. Since the grain size distribution influences the microstructure evolution during subsequent heat treatment (HT) and metal forming operations, considering a more realistic initial distribution can be beneficial for subsequent simulations.

• Influence of Strain Rate on Deformation and Failure Behavior of Sheet Metals under Shear Loading

  S. Klitschke, A. Trondl, F. Huberth (Fraunhofer IWM)

  In order to improve the reliability of deformation and failure prediction of automotive lightweight con-structions in real crash situations, appropriate input data for crash simulations are necessary which re-present the material behavior under high strain rates and complex multiaxial loading situations. Espe-cially under shear dominated loading failure is difficult to reach and there is still a lack of information concerning the strain rate dependency under these loading conditions. Therefore an experimental pro-cedure for strain rate dependent shear tension tests on sheet metals was developed which bases on asymmetrical notched shear tensile specimen geometries without surface processing. The specimen design of the shear zone was optimized by varying the shear length dependent on the sheet thickness and the notch position dependent on material data of uniaxial tension tests. For different advanced high strength steels (AHSS) numerical and experimental investigations were performed regarding the evolution of load paths in the shear zone and near the notch region as well as the failure location. Based on these experimental results and related numerical simulations recommendations are derived for an optimized design of asymmetrical notched shear tensile specimens. These recommendations are dependent on the sheet thickness and on material properties. The experiments should be carried out comparable to strain rate dependent flat tension tests with an appropriate mounting. The sugges-ted specimen design procedure is validated by experiments on steels in a wide range of strength as well as on exemplary batches of aluminum and copper. The shear characterization for AHSS results in large strain values in the shear zone up to failure under quasi-static loading with a significant negative strain rate effect. These experimental results of improved strain rate dependent shear characterization can be used for enhanced failure prediction in the future.

• Influence of the Coupling Strategy in the Numerical Simulation of Electromagnetic Sheet Metal Forming

  Ibai Ulacia, Iñaki Hurtado - University of Mondragon, José Imbert, Michael J. Worswic - University of Waterloo, Canada, Pierre L’Eplattenier - Livermore Software Technology Corporation, USA

  In this paper the Electromagnetic Forming process is numerically analyzed using a novel method that is being implemented into the commercial LS-DYNA® code. The method consists on a combination of a Boundary Element Method (BEM) and a Finite Element Method (FEM) formulations to compute the electromagnetic analysis. The main advantage of using BEM is that the air is not meshed avoiding the related problems and making it easier to couple the interacting fields involved in the EMF process. Sequential coupling and uncoupled strategies for the simulation of the related fields (i.e. electromagnetic, thermal and mechanical fields) are compared. Sequential coupling takes into account the deformation of the work piece are compared with the uncoupled strategy dismisses the deformation of the sample. The importance of the simulation method used is evaluated and compared with experimental results.

• Influence of the Effect of Strain Rates on Springback in Aluminum 2024 (ISO AlCu4Mg1)

  Pravin Kulkarni, Shashikiran Prabhakar - Cessna Aircraft Company

  Forming of aluminum sheets in T-temper is a much sought after industrial process, especially in the aircraft industry. However, the success of this process largely hinges on the ability to predict springback accurately. Aluminum sheets in T-temper exhibit approximately twenty percent variability in material properties and also the amount of springback is very large. This makes tool design for aluminum in T-temper an iterative and difficult to control process. Traditionally aluminum has been formed in the O-temper and then heat-treated to T–temper, as recourse to reduce springback. This research is aimed at developing a predictive finite element technique for springback, using experimental validation. A parametric study was conducted to determine the influence of geometric parameters and tempers on springback. The study characterizes springback of aluminum in different tempers and investigates the effect of forming strain-rates on springback. The study focuses on springback in Aluminum 2024 using hydroforming process.

• Influence of the Residual Welding Phenomena on the Dynamic Properties of a Two-Meter Long Tube with 64 Non-Symmetrical Brackets Welded on a Helical Path

  S.V. Medvedev, M.V. Petrushina, O.P. Tchij - United Institute of Informatics Problems NAS of Belarus

  Welded elements of a two meter long tube is considered. The welded structure rotates with 100rad/sec. The non- symmetrical brackets are connected to the tube through by the welds of a curved trajectory that consists of circumferential parts and arbitrary curved part on a shaft surface and disposed on the tube in a helical sequence. The objective of the study was to explore the axis and hoop stress distribution on the shaft tube and its influence on the dynamic properties of a welded structure. Sample with one element welded to the shaft tube first was studied. Three approaches were used. Temporal and residual stresses and strains were first obtained by means of moving heat source and by means of solving simplified thermomechanical problem assuming weld laying on being simultaneous along the weld path. Cooling process was important in both methods. Third approach is an own method based on shrinkage forces notion which implementation needs only strength analysis formulation. Its correctness and applicability to the case of weld paths under study was checked. The residual welding deformations obtained by all methods were then compared with the deformations of samples welded in manufacturing conditions.

• Influence of Variations in a Mechanical Framing Station on the Shape Accuracy of S-Rail Assemblies

  K. Wiegand, T. Konrad, (Daimler), M. Merklein (University of Erlangen-Nürnberg)

  In virtual production planning, recent publications showed the possibility of creating a digital process chain of body parts including the process steps in the press shop and body-in-white shop. The digital process chain is used to get an early impression of the shape accuracy of assemblies regarding the used single parts. Within the entire process chain a huge variety of factors influence the shape accuracy of (sub)assemblies. However, not every parameter of the deep drawing and assembly process exerts significant influence on the assembly quality and on process stability.

• Injection Molded Energy Absorber (Ultramid® PA-GF30) in the Front End of Mercedes-Benz S-Class MY2020

  L. Juhasz, A. Wüst, S. Glaser, S. Ebli, T. Hensel, (BASF), G. Summ, M. Herok, G. Jäger (Daimler)

  Energy management in passenger cars has traditionally been dominated by metal structures due to high energy demand and structural integrity. Due to changing legislation and increasing requirements, the trend in vehicle development is towards spatially distributed energy management concepts, leading to more and new load paths. Euro NCAP to frontal MPDB test is to be mentioned here. To serve these new load paths, new absorbers would actually be needed.

• Innovative modeling capabilities in virtual.lab in view of cross attribute simulation

  Tom Van Langenhove, Cedric Canadas, Nick Tzannetakis, Christophe Liefooghe - LMS International

  To meet the challenge to support the development of an ever increasing number of vehicle models and variants with an optimal quality in the constantly decreasing resource and time requirements, companies are forced to increase the integration amongst and impact of the different simulation disciplines in the core vehicle design and engineering process. A proposed methodology is offered by LMS through the LMS Virtual.Lab Software suite proposing an integrated platform for body, chassis, engine and full vehicle engineering. Through its integration in Dassault Systemes PLM and Simulia solutions it tightly links multi-attribute simulation with vehicle design. Innovative assembly and modelling capabilities enable a unique bridge between the different vehicle attribute domains, being noise & vibration, durability, strength and crash/impact. The definition of a generic assembly, which can be even defined directly on the design model represented by CAD together with multi-solver modelling information, and a multi-solver pre/post environment seamlessly integrating leading crash, linear, and non-linear solvers (LS-DYNA, Nastran, Abaqus) allows an easy and thorough information and data sharing between the different disciplines, strongly increases the efficiency in creating subsystem and vehicle models and delivers optimal collaboration between design and engineering teams. This paper focuses on a comprehensive presentation of the methodologies employed, clearly demonstrates the aims and value that a multi-attribute PLM integrated solution brings, documented by real industrial examples and metrics.

• Input Parameters for Metal Forming Simulation Using LS-DYNA

  Bradley N. Maker, Xinhai Zhu - Livermore Software Technology Corporation

  LS-DYNA has been widely used to study automotive crash. Default input parameters are generally chosen to give efficient, accurate crash simulation results. These defaults are not necessarily optimal for metal forming simulations. The following presents a standard procedure for conducting metal forming simulations with LS-DYNA. Recommended input parameters are identified in boldface type and included in boxed keyword input syntax for quick reference. A boldface zero value is entered for required input data which is model specific, such as the termination time term.

• INPUT PARAMETERS FOR SPRINGBACK SIMULATION USING LS-DYNA

  Bradley N. Maker, Xinhai Zhu - Livermore Software Technology Corporation

  LS-DYNA has been applied to springback simulation by a large number of users, with generally mixed results. Some results have demonstrated 70% accuracy or better, while others have been entirely misleading. In order to eliminate inconsistent results, this report presents a standard procedure for conducting springback simulations with LS-DYNA. The “seamless” and “dynain” methods for springback are described, followed by a description of general implicit springback problem set-up. Recommendations are given for anticipating and improving springback prediction accuracy. Wherever possible, LS-DYNA keyword input data is shown to clarify the presentation. Recommended input parameters are identified in boldface type and included in boxed keyword input syntax for quick reference. A boldface zero value is entered for required input data which is model specific, such as the termination time term.

• INTEGRATED ANALYSIS OF FORMING AND CRASHWORTHINESS OF HIGH STRENGTH ALUMINIUM BUMPERS USING LS-DYNA

  O.P. SØVIK, A. ARTELIUS, T.J. BROBAK - Hydro Automotive Structures

  The front and rear bumper beams are important parts of the overall safety system of modern cars. Due to aluminium's high strength to weight ratio, bumper beams made of extruded aluminium profiles have become an attractive contribution to the car manufacturers’ constant strive for reducing the weight of their cars. In order to meet the various demands with respect to weight, strength, functionality, packaging , etc., a significant degree of complex forming after extrusion is normally required. As a leading supplier of high strength aluminium bumpers, Hydro Automotive Structures have for several year been using advanced FE tools in their product and process development. However, due to the close link between crash performance and geometrical shape of the bumper, the need for a tighter integration between process and product simulations has been realised. The present paper shows examples of how such integrated analyses are carried out in an industrial context as well as some results indicating the clear benefits of such an approach.

• Integrating LSTC and MSC.Software Technology for Explicit Dynamics and Fluid-Structure Interaction

  Erik Plugge - MSC.Software Benelux B.V.

  LSTC and MSC.Software have entered a long-term strategic partnership, with the objective of integrating complementary technology to the benefit of the structural and fluid dynamics community. This paper presents some of the technical aspects of this integration, highlights the technologies being used, and demonstrates the new application capabilities being enabled by this partnership. The presentation will focus on two aspects of code coupling. Firstly, between MSC.Software’s MSC.Dytran Eulerian solver and LSTC's LS-DYNA explicit solver, and secondly the integration of LS-DYNA explicit solutions via the SOL700 sequence in MSC.Nastran. Both the Eulerian solver in MSC.Dytran and the structural explicit solver in LS- DYNA are unique in their class. Coupling the two codes together allows FSI (Fluid-Structure Interaction) simulations to be run efficiently and on a high level of accuracy and speed. Similarly, coupling of the LS-DYNA explicit solver with MSC.Nastran via SOL700 enables a new range of applications in crash and impact from within a general-purpose structural environment. This paper describes technical aspects of how these code integrations have been developed, and presents a range of application areas and examples of the new dynamics and fluid-structure interaction capabilities achieved.

• Integrating plastics molding and structure dynamics analysis by leveraging LS-DYNA, MOLDEX3D and PRESYS

  Allen Y. Peng, Emily Wu, C.T. Huang - CoreTech System (Moldex3D) Co.

  An increasing number of automotive or consumer electronics parts are made of engineering plastic for its low cost and superior material properties. The traditional structure analysis for injection-molded plastics part is to perform CAE analysis based on the assumption of one or several isotropic materials. However, the material characteristic of plastic part is extremely dependent on molding process. The process-induced properties, such as fiber-induced anisotropic mechanical properties or weld-line defects, might not be favorable to the structural requirement of final products. Besides, the mesh requirement for different analysis purposes might not be the same, either. In this topic, we integrate the CAE analysis of structure and plastics molding through the integration of LS-DYNA, Moldex3D, and PreSys. This approach shows the effects of mutually dependent analyses have been successfully examined in some injection-molded parts.

• Integration of Finite Element Analysis (LS-DYNA) with Rigid Body Dynamics (ATB) for Crash Simulation

  Bhavin Mehta, Shr-Hung Chen, Srikanth Patlu, Prasad N. Petkar, Robert L. Williams - Ohio University, Lee P. Bindeman - LSTC, James M. Kennedy - KBS2 Inc., Joseph Pellettiere - Wright-Patterson Air Force Base

  This paper describes the Integration of ATB (Articulated Total Body), a rigid body dynamics program and LS-DYNA, a finite element analysis program for PC-based occupant/seat restraint modeling. The integration of ATB and LS-DYNA provides a single simulation tool with the advantages of each individual code. The results of several cases and validation are also described in detail. The output of the coupled software is found to be consistent with the output from the already validated ATB program.

• Integration of Morphing and Optimization with the CAx-Load Case Composer at AUDI

  Dr. Holger Meissner - AUDI AG, Marko Thiele - DYNAmore GmbH

  The increasing demand to evaluate vast amounts of different load cases has led to a highly standardized and automated way of model assembling at AUDI. This model assembling is greatly assisted by the software “CAx Load Case Composer” which has been developed by DYNAmore in cooperation with AUDI. The Loadcase Composer (LoCo) provides the user with convenient ways to manage FE-model include files and allows to automatically select appropriate include files for each load case. Thus the use of redundant includes can be avoided or at least reduced by significant amounts. One mayor concept of LoCo is the capability of integrating parameters in the FE input files. Parameters for design changes, such as for example airbag settings or seat/dummy transformations can be specified and administrated within the software. This allows the user to apply parameter studies, optimization and stochastic analysis very fast and easily. Through the integration of LS-OPT in LoCo, powerful optimization algorithms can be employed. In this paper it is shown how morphing parameters for geometrically shape changes have been integrated in LoCo. This will be demonstrated with an example. The close integration into the standardized simulation workflow allows performing parameter studies of shape design changes with a minimum effort. In addition, it can be used in conjunction with the LS-OPT integration in LoCo. Together with LS-OPT and LoCo an engineer at AUDI has the ability to set up an optimization with very little effort. Thus it allows that optimization, parameter studies and stochastic analysis become operations of daily use.

• Integration of Morphing and Optimization with the CAx-Load Case Composer at AUDI

  Dr. Holger Meissner - AUDI AG, Marko Thiele - DYNAmore GmbH

  The increasing demand to evaluate vast amounts of different load cases has led to a highly standardized and automated way of model assembling at AUDI. This model assembling is greatly assisted by the software “CAx Load Case Composer” which has been developed by DYNAmore in cooperation with AUDI. The Loadcase Composer (LoCo) provides the user with convenient ways to manage FE-model include files and allows to automatically select appropriate include files for each load case. Thus the use of redundant includes can be avoided or at least reduced by significant amounts. One mayor concept of LoCo is the capability of integrating parameters in the FE input files. Parameters for design changes, such as for example airbag settings or seat/dummy transformations can be specified and administrated within the software. This allows the user to apply parameter studies, optimization and stochastic analysis very fast and easily. Through the integration of LS-OPT in LoCo, powerful optimization algorithms can be employed. In this paper it is shown how morphing parameters for geometrically shape changes have been integrated in LoCo. This will be demonstrated with an example. The close integration into the standardized simulation workflow allows performing parameter studies of shape design changes with a minimum effort. In addition, it can be used in conjunction with the LS-OPT integration in LoCo. Together with LS-OPT and LoCo an engineer at AUDI has the ability to set up an optimization with very little effort. Thus it allows that optimization, parameter studies and stochastic analysis become operations of daily use.

• Integration of Simulation in the Development Process

  J. Brockmann - Faurecia Autositze GmbH & Co. KG

• Integrative crash simulation of composite structures

  Stefan Glaser- Andreas Wüst - Engineering Plastics Europe - KTE

  -- Integrative Simulation? - Motivation - Fiber orientation in filling process - Material modelling - Influence of fiber orientation tensor -- Simulation applications - Simulation of material tests - Static loading - Crash loading

• Integrative Optimization of injection-molded plastic parts - Multidisciplinary Shape Optimization including process induced properties

  Andreas Wüst, Torsten Hensel, Dirk Jansen - BASF SE

  The Integrative Approach described in this paper incorporates effects of the part’s manufacturing process (here: injection molding) into a new workflow for optimization of the part performance. The new approach is able to close the gap between process simulation/optimization and mechanical simulation/optimization. New classes of design variables linked to the manufacturing process complicate the workflow of the optimization. The newly introduced optimization discipline “manufacturing simulation” acts as a preprocessing step for all other disciplines while it can simultaneously be seen as a full optimization discipline as well. Shape optimization by morphing is included as well and further complicates the workflow. The paper outlines the necessary changes in the workflow and discusses the influence in different optimization scenarios. In a first example the prototype workflow based on state-of-the-art software packages and newly developed script and interface tools was designed, defined and proved to work. A screening phase as well as an optimization had been done with reasonable results. The part considered in this study is a thermoplastic structure, manufactured by injection molding. The most important process induced changes are based on the anisotropic orientation of short glass fibers in the material during filling. These effects had been taken into account using BASF’s ULTRASIMTM software. Filling simulation as well as warpage simulation and a mechanical impact simulation were used as single optimization disciplines.

• Integrative Optimization of injection-molded plastic parts - Multidisciplinary Shape Optimization including process induced properties

  Andreas Wüst, Torsten Hensel, Dirk Jansen - BASF SE

  The Integrative Approach described in this paper incorporates effects of the part’s manufacturing process (here: injection molding) into a new workflow for optimization of the part performance. The new approach is able to close the gap between process simulation/optimization and mechanical simulation/optimization. New classes of design variables linked to the manufacturing process complicate the workflow of the optimization. The newly introduced optimization discipline “manufacturing simulation” acts as a preprocessing step for all other disciplines while it can simultaneously be seen as a full optimization discipline as well. Shape optimization by morphing is included as well and further complicates the workflow. The paper outlines the necessary changes in the workflow and discusses the influence in different optimization scenarios. In a first example the prototype workflow based on state-of-the-art software packages and newly developed script and interface tools was designed, defined and proved to work. A screening phase as well as an optimization had been done with reasonable results. The part considered in this study is a thermoplastic structure, manufactured by injection molding. The most important process induced changes are based on the anisotropic orientation of short glass fibers in the material during filling. These effects had been taken into account using BASF’s ULTRASIMTM software. Filling simulation as well as warpage simulation and a mechanical impact simulation were used as single optimization disciplines.

• Intel Cluster Ready Support for LS-DYNA®/MPP

  Tim Prince - Intel Corporation

  The Intel Cluster Ready program enables LS DYNA/MPP users to buy, install, and use clusters more effectively. It includes a joint Intel and cluster supplier certification process to ensure the cluster the LS-DYNA user purchases is designed and built to specification. Intel supplied software tools support verification of initial and ongoing operation and performance of the cluster.

• Intelligent Multiscale Simulation Based on Process-Guided Composite Database

  Zeliang Liu, Haoyan Wei, C.T. Wu (Livermore Software Technology LLC), Tianyu Huang (Livermore Software Technology LLC / Northwestern University)

  In the paper, we present an integrated data-driven modeling framework based on process modeling, material homogenization, mechanistic machine learning, and concurrent multiscale simulation. We are interested in the injection-molded short fiber reinforced composites, which have been identified as key material systems in automotive, aerospace, and electronics industries. The molding process induces spatially varying microstructures across various length scales, while the resulting strongly anisotropic and nonlinear material properties are still challenging to be captured by conventional modeling approaches. To prepare the linear elastic training data for our machine learning tasks, Representative Volume Elements (RVE) with different fiber orientations and volume fractions are generated through stochastic reconstruction and analyzed using the LS-DYNA® RVE package. More importantly, we utilize the recently proposed Deep Material Network (DMN) to learn the hidden microscale morphologies from data. With essential physics embedded in its building blocks, this data-driven material model can be extrapolated to predict nonlinear material behaviors efficiently and accurately. Through the transfer learning of DMN, we create a unified process-guided material database that covers a full range of geometric descriptors for short fiber reinforced composites. Finally, this unified DMN database is implemented and coupled with macroscale finite element model in LS-DYNA to enable concurrent multiscale simulations. From our perspective, the proposed framework is also promising in many other emergent multiscale engineering systems, such as additive manufacturing and compressive molding.

• Interaction Methods for the SPH Parts (Multiphase Flows, Solid Bodies) in LS-DYNA®

  Jingxiao Xu, Jason Wang (LSTC)

  Smooth particles hydrodynamics is a meshfree, Lagrangian particle method for modeling fluid flows and solid bodies. It has been applied extensively to the multiphase flows, heat conduction, high explosive problems and so on. In this paper, different interaction methods available in the LS-DYNA for SPH parts which have wide range of density and material properties are studied and compared. Node to node contacts fit well for the interaction between two SPH parts with high density ratio, the standard SPH interpolation method has better accuracy around the interfaces when two SPH parts have similar density and material properties. Different interaction approaches can be combined together in one model to reach the best results. Also the interactions between Lagrangian elements with SPH particles are discussed. Some examples are presented to show how to use different approaches with different combination of LS-DYNA keywords.

• InteractionPossibilities of Bonded and Loose Particles in LS-DYNA®

  Nils Karajan (DYNAmore GmbH, Germany), Zhidong Han, Hailong Ten, Jason Wang (LSTC)

  The goal of this presentation is to outline the current development status of LS-DYNA® with respect to simulations using the discrete-element method (DEM), which is based on Cundall & Strack [1]. Starting with assemblies of loose discrete spherical particles, different types of granular media can be discretized to predict their behavior, for instance, during mixing processes, storage and discharge in silos or transportation on belts. Following this, the interaction of the discrete particles with themselves as well as their surrounding deformable or rigid structures can be taken into account. Herein, friction coefficients as well as spring and damping constants can be defined in normal and tangential direction. Wet particles can be estimated with the aid of a capillary force model. Even though the geometric shape of the particles is always spherical, a certain roughness of the grains can be achieved by introducing a rolling friction or by defining clustered particles using bonds. Moreover, with the introduction of bonded particles, linear-elastic solid material behavior can be modeled. Herein, the mechanical behavior of the bonds may either be prescribed manually or computed internally by LS-DYNA in an automated fashion using the elastic constants given in a material card. With the definition of a fracture energy release rate of the bonds, fracture mechanics of brittle materials can be studied. Herein, the number of bonds of a particle to the neighboring particles can be defined with a bond radius. Note that the breakage of single bonds can be interpreted as micro cracks that eventually evolve to macro cracks. This presentation will give an overview of the involved material cards and provides information on how the cards are used. For a better understanding of the involved parameters, simple examples will be presented addressing particle-particle as well as particle-structure interaction.

• Interactive Dynamic Analysis of Subsea Lifting Ropes

  George Laird, Kirk Fraser (Predictive Engineering, Inc.), Ryan Marsh (Sound Ocean Systems, Inc.)

  The dynamic movement of subsea ropes presents an interesting numerical challenge due to the coupling of drag forces with the dynamic response of the rope. Although a FSI approach of fully coupling the surrounding seawater to the rope is theoretically possible it lies beyond the reach of practical engineering when discussing rope lengths in kilometers and possible rope movements in hundreds of meters. A new analysis technique is presented where the drag forces associated with subsea dynamic rope movement are directly integrated into the solution using the LS-DYNA® user subroutine, LOADUD. Drag forces are calculated from analytical solutions to provide discrete drag forces as a function of rope position and velocity. This technique avoids the complexity of a fully-coupled FSI solution while providing the major benefits capturing how the rope will dynamically move while lifting heavy loads while being subjected to strong sea currents. Results are presenting showing how a two kilometer rope would dynamically behave while lifting a heavy load from sea bottom to surface under stratified sea currents.

• Interface ANSYS Workbench for LS-DYNA

  M. Hörmann - CADFEM GmbH

• Interpretation of Deformation Pattern in Automotive Rails in Frontal Impact

  Joseph Hassan, K. Ding, G. Nusholtz - DaimlerChrysler Corp. USA

  Two barriers are commonly used to evaluate the response of a vehicle in a frontal impact: the rigid barrier and the offset deformable barrier. They produce different deformation patterns, which opens up the possibility that at least one of them does not represent real world crashes. One possible cause of the difference is that an impact into a rigid barrier generates significantly greater stress waves than impacts in the real world resulting in final deformation patterns that are different from those seen in the field. To evaluate this conjecture models of two types of rails each undergoing two different types of impacts, are analyzed using an explicit dynamic finite element code. Results show that the energy perturbation along the rail depends on the barrier type and that the early phase of wave propagation has very little effect on the final deformation pattern. This implies that in the real world conditions, the stress wave propagation along the rail has very little effect on the final deformed shape of the rail.

• Introducing Arup-Cellbond MDPB Shell Model

  Laura Rovira Crespo, Mattia Bernardi, Dong-Ling Li, Zhao Bao, Zhi Zou, Yi-Ning Ding, Maya Shinozaki, Francois Lancelot (ARUP)

  This Mobile Offset Progressive Deformable Barrier (MPDB) for frontal impact model has been developed to take advantage of the latest developments in the LS-DYNA® code and is designed to provide robust and efficient analysis. In this paper, some details of the calibration and validation process will firstly be presented, which not only satisfies performance requirements set by regulations (Euro NCAP 2020 Dynamic Tubular Impactor test) but also goes beyond through rigorous calibration against other physical tests (Vertical/Rounded Impactor Test, Quarter Wall test etc). Arup and Cellbond worked closely with Jaguar Land Rover in the UK for the development of this barrier model through ensuring correlation to full speed, real vehicle tests. Finally, methods of how to automate post-processing of results (including the calculation of Euro NCAP compatibility modifier) using the Oasys Software will be demonstrated.

• Introducing J-SimRapid, A New Reduction Modelling Tool for Vehicle Crash Simulation

  Shinya Hayashi, Shinya Hiroi, Norio Shimizu

  Demands for ever increasing efficiency of automotive crash analysis have continued to rise in the drive to reduce automotive development costs. When major design changes are required to satisfy product performance late in the development process, significant cost and time are required to implement them. To alleviate this, automotive manufacturers have adopted the concept of "front-loading" to identify problems early-on in the development process.

• Introducing New Capabilities of JFOLD Version 3 and Airbag Folding Examples

  Richard Taylor (Ove Arup & Partners International Limited), Shingo Yagishita, Shinya Hayashi (JSOL Corporation)

  A software tool called JFOLD has been developed by JSOL Corporation to enable successful airbag folding using LS-DYNA ® . This paper introduces some new capabilities of JFOLD Version 3 and demonstrates folding examples. JFOLD runs inside the powerful and popular pre-processor Primer. JFOLD Version 1 was released in July 2013 and has been continuously developed to make folding airbags quicker and easier.

• Introduction of a New Function, (CONTROL_FORMING_SCRAP_FALL),in LS-DYNA & Its Applications in Scrap Fall Simulation

  J. Gu, Y. Hu, X. Lu (Ford Motor Co.), X. Zhu, L. Zhang (LSTC)

  In stamping plants, one of the most common defects is scrap fall failure, in which some of the trimmed scraps do not fall according to the designed chutes or intended path. The scrap fall failure can damage dies or/and panels and cause stamping production line shutdown, which could easily result in millions of dollars lost. This paper is focused on developing effective analytical tools to detect potential scrap fall failures in tool/die design stages. Scrap cutting/separation from its parent sheet metal is an important step in properly simulating the scrap falling sequence. There are several critical characteristics which need to be properly captured by an analytical method in order to "detect" scrap fall errors. First, many broken-off scraps carry the initial kinematics and dynamics from the upper moving trim steel through contact during the trim process. Second, the trimming action is not simultaneous along the trim curve even in most simple direct trims. In complex cases such as multiple direct trim processes or mixture of direct trim and cam trim, the sequence of the scrap separation is very different from one design to another. In addition to the scrap separation sequence and the initial kinematics and dynamics of the scrap, contact between scrap and low trim steel and post is another very critical factor to the trajectory of the scrap fall. Some efforts ([1], [2], and [3]) have been made to understand and detect the root causes of scrap fall issues. To our best knowledge, there are no methods available today which could consider all three above factors accurately. Therefore, simulation results from those methods might not yield the results observed in the stamping plants (refering to some cases presented in the paper). To capture above mentioned three characteristics in simulation of scrap fall, a new function, called CONTROL_FORMING_SCRAP_FALL in LS-DYNA, has been jointly developed by Ford and LSTC. In this paper, we will first reveal the basic parameters employed in the new function, and illustrate how they are used to simulate the scrap separation & falling with a few simple cases. Then, several complex examples will be shown to illustrate how the new function along w/ LS-DYNA existing capabilities to be able to simulate real trimming processes accurately (to capture above mentioned three key characteristics) and detect scrap fall failures.

• Introduction of an Electromagnetism Module in LS-DYNA for Coupled Mechanical-Thermal-Electromagnetic Simulations

  Pierre L’Eplattenier, Grant Cook, Cleve Ashcraft, Mike Burger, Art Shapiro - Livermore Software Technology Corporation, Glenn Daehn, Mala Seth - The Ohio State University

  A new electromagnetism module is being developed in LD-DYNA for coupled mechanical/thermal/electromagnetic simulations. One of the main applications of this module is Electromagnetic Metal Forming. The physics, numerical methods and capabilities of this new module are briefly presented. This module is then illustrated on different simulations. A first set of simulations corresponds to a ring expansion experiment, which was performed at The Ohio State University, for which the code is compared with experimental results. A second example corresponds to a typical Electromagnetic Metal Forming of a thin metallic sheet.

• Introduction of Die System Module in LS-PrePost®

  Chunjie Zhang, Philip Ho, Xinhai Zhu (LSTC)

  Die system module (DSM) is developed to generate tool geometry in an early stage and to evaluate these result by forming simulation. DSM Graphics User Interface is designed to provide metal forming users a tool to generate die face more effectively. The main focus of module is placed on easy modification and reuse of existing design. This paper illustrates the algorithm and some special feature of DSM

• Introduction of ISPG Method and Geometric Multiscale Modeling for Electronics Solder Reflow and Shock Wave Analysis

  D. Lyu, W.Hu, X. Pan, C. T. Wu (Ansys/LST)

  Solder joints have become the main mechanical and electrical connections in modern microelectronics packaging for most consumer electronics products and they are typically observed to be the weakest links in terms for structural strength in the drop shock event. A drop shock simulation involves modeling the shock wave effect on mesoscale solder joints and macroscale chip packages concurrently, which is a typical multi-scale problem. Conventional finite element approaches using beam elements for the representation of the solders and the one-way sub-modeling technique cannot offer a high-fidelity solution. In addition, the shape of the solder ball is a very important contributory factor in determining the local stress levels and it is impractical to obtain all solder ball geometries by experimental measurement. Therefore, an effective simulation tool for the prediction of solder ball shape in the solder joint design as well as for the drop shock analysis is required in electronics industry.

• Introduction of LS-DYNA® MCOL solver coupling with Ansys Aqwa for the application in shipbuilding analysis

  Zhe Cui, Yu Bi, Arwel Davies, Shuangxing Du, Yun Huang

  For the ship building industry, ship accidents continue to occur regardless of efforts to prevent them. Some extreme or accidental situations such as collision and grounding need to be considered at the design stage. The rigid body dynamic program MCOL was developed in LS-DYNA and used in simulation of ship collisions analysis. The MCOL solver requires an input file as .mco file containing the hydrodynamic parameters such as the rigid body added mass matrix, hydrostatic restoring matrix, buoyancy parameters, and wave damping matrices for the body, etc. These parameters were provided by third-party software previously. In this paper, the new development on LS-DYNA/MCOL-Aqwa coupling analysis has been implemented in which the Aqwa solver can automatically create the MCOL required hydrodynamic database, .mco file.

• Introduction of Rotor Dynamics Using Implicit Method in LS-DYNA®

  Liping Li, Roger Grimes (LSTC)

  Rotor dynamics is commonly used to analyze the behavior of structures ranging from jet engines and steam turbines to auto engines and computer disk drives. In such applications, the amplitude of structural vibration can become excessive when the speed of rotation approaches the system’s critical speed. This paper introduces a primary implementation of rotor dynamics in LS-DYNA and presents a validation study of this new implemented feature with exiting theoretical studies, as well as another finite element method software ANSYS. The structural vibration responses of four different models with beam, shell and solid elements, the shaft whirling orbit and Campbell diagrams are compared. It shows that the results from LS-DYNA have very good agreements with theoretical results and ANSYS simulation results. So it suggests that the LS-DYNA simulation is accurate for the cases investigated in this paper.

• Introduction of Rotor Dynamics using Implicit Method in LS-DYNA ®

  Liping Li, Roger Grimes (LSTC), Thomas Borrvall (DYNAmore Nordic AB)

  Rotor dynamics is commonly used to analyze the behavior of structures ranging from jet engines and steam turbines to auto engines and computer disk drives. This paper introduces the implementation of rotor dynamics in LS-DYNA. The structural transient analysis and mode analysis and other applications, like brake squeal analysis, are presented and validated with other finite element software.

• Introduction of Sliding Capabilities in the ICFD LS-DYNA® Solver

  Iñaki Çaldichoury, Chienjung Huang, Facundo Del Pin, Rodrigo Paz (Livermore Software Technology, an Ansys company)

  Sliding mesh is a technique that prevents excessive re-meshing in problems that involve rotating parts. It is ideal for solving transient problems in turbo-machinery. Overset mesh techniques on the other hand typically contain the body of interest for the study around which a fine fluid mesh in constructed. That initial domain is then superimposed on a background mesh containing the surrounding geometry with data being interpolated between the two. Other techniques include using a non-inertial rotating frame or using immersed FSI techniques. Within LS-DYNA, the ICFD solver has seen a continuous growth of users that wish to simulate increasingly complex multiphysics problems involving moving structures, thermal heating, particle displacement and sometimes magnetic fields. As such, it is imperative to offer as many advanced CFD capabilities and solving tools to the users as possible. Among those, sliding mesh has been amongst the most prominent requests. In this paper, the current state of development will be presented, along with a description of the algorithm used as well as some examples and some benchmarking results.

• Inverse Engineering and Preliminary Simulation of a Closed Profile Roll-forming Line

  R. Perez-Santiago, A. Garcia, C. Sarmiento, R. Berlanga, M. Castellanos (Metalsa S.A. de C.V., ), M. Hernandez, P. Zambrano, O. Lopez (Universidad Autónoma de Nuevo León)

  Roll-forming is a key technology among Metalsa ́s manufacturing capabilities. The Company’s technology group is conducting research oriented to support future engineering changes and the development of new technology variants. The initial objective of the project is the development of a reliable simulation of one complete roll-forming line using LS-DYNA®. The roll-forming tools were digitized using an optical scanner, converted to 3D parts and finally assembled into the complete forming line. This geometry served as base to generate a finite element model, which was entirely set-up using LS-PrePost®. As a first trial, the elasto-plastic behavior of the sheet strip was modeled utilizing generic material properties. In order to validate the analysis procedure, the production line was halted to allow geometry measurement of cross sections at different forming stations. This article describes the whole procedure utilized along with the comparison of the numeric and physical profiles obtained from the forming process. The numerical model yielded an accurate prediction of the deformed profile. This methodology is used on all virtual validation of new designs before commissioning equipment modification or purchasing.

• Investigating the Influence of Local Fibre Architecture in Textile Composites by the Help of a Mapping Tool

  M. Vinot, M. Holzapfel (DLR); C. Liebold (DYNAmore)

  Standard approaches for the modelling and simulation of composite structures rely on the homogenisation of material properties on unidirectional plies. Doing so, simulations lose the ability to precisely describe local phenomena and complex failure mechanisms. In the research campus ARENA2036, the project DigitPro (Digital Prototype) develops a method based on a closed simulation process chain to take into account potential production effects by braided or woven composite structures. Starting from the process simulation, crucial information like fibre orientation and waviness is mapped on a target mesh for structural analysis. The resulting model is then investigated and potential needs to change the component’s geometry or the manufacturing process are detected. The mapping tool Envyo®, developed at DYNAmore, offers various possibilities for the transfer of information generated from process simulation. Thus, it is necessary to investigate the impact of mapping algorithms and respective parameters on the structure simulation. The present paper details the mapping procedure for textile composites. The influence of local fibre architecture is finally investigated on a generic structure and compared to a standard approach.

• Investigating the Post Processing of LS-DYNA® in a Fully Immersive Workflow Environment

  Ed Helwig, Facundo Del Pin, Livermore Software Technology Corporation, Livermore CA

  The use of virtual reality (VR) in engineering applications has been expanding for the last decade. Immersive technology is quickly becoming a tool for pre and postproduction decision-making and analysis. Virtual reality can assist in reducing the number of physical prototypes, build collaboration between various engineering disciplines, speed up time to manufacturing, and reduce the number of design cycles. We examined the integration of LS-DYNA into a workflow using results from a fluid-structure interaction problem. The expected outcome was to generate life like 2D and 3D simulation models, while maintaining a high degree of engineering data in the analysis output. Additionally, simulation data was placed in a computer aided virtual environment (CAVE) using a passive visualization solution, and eliminating the requirement for an active VR headset. The investigation identified key hardware and software considerations while optimizing the workflow process. Scalability, computation time, component costs and functionality were variables considered during development. It is our firm belief that seamlessly integrated visualization tools and state of the art physics solvers are in the core of future design and manufacturing pipelines.

• Investigating the Vibration Behavior and Sound of Church Bells Considering Ornaments and Reliefs Using LS-DYNA

  Alexander Siebert, Gunther Blankenhorn, Karl Schweizerhof - University Karlsruhe, Germany

  A numerical investigation of the vibration behavior and the sound of a specific bell is performed and validated by experimental modal analysis. In the numerical simulations a number of modifications of the geometry mimicking or- naments and reliefs is investigated as such ornaments have lead to mistunes in a very popular case in Germany. It is also shown, how the influence of ornaments on the modification of eigenfrequencies can be reduced. The numerical results obtained by eigenvalue analyses as well as transient analyses with LS-DYNA compare very well with the experimental results. It is shown that LS-DYNA- Finite Element analysis can be well used for bell de- sign [14].

• Investigation and Application of Multi-Disciplinary Optimization for Automotive Body-in-White Development

  Allen Sheldon, Edward Helwig - Honda R&D Americas, Yong-Bae Cho - CSM Software

  A process has been created for applying multi-disciplinary optimization (MDO) during the development of an automotive body-in-white (BIW) structure. The initial phase evaluated the performance of several different optimization algorithms when applied to structural MDO problems. From this testing, two algorithms were chosen for further study, one of these being sequential metamodeling with domain reduction (SRSM) found within LS-OPT. To use the LS-OPT optimization software effectively within a production environment, adaptations were made to integrate it into an established CAE infrastructure. This involved developing a LS-OPT server and architecture for the parallel job submission and queuing required in the MDO process. This enabled LS- OPT to act as an integral part of the enterprise CAE architecture as opposed to a standalone tool. Within this integrated environment, the SRSM method has been applied to an MDO process that combines 7 load cases and takes into account crash and NVH requirements. The objective of the MDO was to minimize mass while constraints enforced the performance requirements of each load case. The thicknesses of 35 parts were considered in this MDO. The application of the SRSM MDO strategy resulted in an optimized design with a 6% weight reduction for the portion of the BIW considered. The optimized design was determined with reasonable computational resources and time considering the computational intensity of the analysis.

• Investigation into the rising air pressure inside the door during side impacts

  Michael Machens - Wilhelm Karmann GmbH, Thomas Wessels - FH Osnabrück

  A crucial point in side impacts is the rapid intrusion of the side structure of the door into the passenger compartment. In the initial stage of the crash it is essential to provide sufficient space between occupant and door trim to enable a proper unfolding of the side airbag. This problem can be alleviated by using the rising air pressure inside the door as an additional input for crash sensing. When combined with the common acceleration sensing on the centre tunnel or B-Pillar it is feasible to increase the sensitivity of the impact detection so that an earlier airbag triggering in side impacts can be achieved. However, because of the introduction of more demanding side impact test configurations this phenomenon still needs to be investigated. In the early development process side impact simulations are usually employed to estimate the available space for airbag unfolding. But these simulations have shown some discrepancies if kinematics of the door trim intrusion during the airbag unfolding phase is compared to the experiments. This can be attributed to a lack of consideration of the air inside the door. A method to simulate this phenomenon which incorporates fluid-structure interaction is given in LS-DYNA. Recent developments in this software allow the use of an Arbitrary Lagrangian-Eulerian (ALE) solver and therefore make it possible to simulate the airflow inside and out of the door during a side impact. Using this approach, the dynamic pressure distribution inside the door and the loss of pressure due to outflowing air was simulated. Within the scope of this study the predictability of the pressure signal recorded for crash sensing and the additional air-induced intrusion of the door trim which reduces space for airbag unfolding is investigated in comparison to the different side and pole impact experiments.

• Investigation of *MAT_58 for Modeling Braided Composites

  Brina J. Blinzler, Wieslaw K. Binienda - University of Akron, Akron Ohio, Robert K. Goldberg - NASA Glenn Research Center, Cleveland Ohio

  An in-depth analysis is needed to simulate the impact behavior of triaxially braided composite materials. Before an impact simulation can be generated, all material input parameters must be found. The objective of this work is to use static tests conducted on axial and transverse coupons to determine these input parameters. In particular, analysis methods that capture the architecturally dependent damage observed in these tests in a computationally efficient manner are required. A macromechanical shell element based model for braided composites has been developed, in which the braid architecture is approximated as a series of four parallel laminated composites with varying fiber orientations. The composite damage model *MAT_58, available within LS- DYNA®, is used in this investigation. Careful investigation of the model’s global response, and local stress and strain distribution within each element of the composite unit cell are examined parametrically using various input strength parameters. From these studies, relatively small changes in the input parameters have been found to have a significant effect on the overall response, sometimes in non-intuitive ways. Thru this investigation the predictive capability of the developed braid model will be improved and a greater understanding of the functionality of the MAT_58 material model will be obtained.

• Investigation of Accuracy Improvement on Crashworthiness Simulation with Pre-Simulation of Metal Forming.

  Katsuhiko TAKASHINA, Kazuhiro UEDA, Takeo OHTSUKA - MITSUBISHI MOTORS CORPORATION

  To improve the accuracy of crashworthiness simulation, it is preferable to consider the effects of metal forming. However, this approach was difficult in practice since analyzing the stamping simulation in detail requires much work. This paper describes the influence of residual strain, work hardening and material thickness changes resulting from the stamping process on the crashworthiness simulation. In almost all impact load cases, the results show that deformation is reduced by the work hardening effects. These results are verified by actual experimental data.

• Investigation of Accuracy Improvement on Crashworthiness Simulation with Pre-Simulation of Metal Forming.

  Katsuhiko TAKASHINA, Kazuhiro UEDA, Takeo OHTSUKA - MITSUBISHI MOTORS CORPORATION

  To improve the accuracy of crashworthiness simulation, it is preferable to consider the effects of metal forming. However, this approach was difficult in practice since analyzing the stamping simulation in detail requires much work. This paper describes the influence of residual strain, work hardening and material thickness changes resulting from the stamping process on the crashworthiness simulation. In almost all impact load cases, the results show that deformation is reduced by the work hardening effects. These results are verified by actual experimental data.

• Investigation of Delamination Modeling Capabilities for Thin Composite Structures in LS-DYNA®

  S.A. Muflahi, G. Mohamed, S.R. Hallett (University of Bristol)

  Predictive capabilities to simulate the initiation and propagation of delamination in thin composite laminates have been investigated. Different element formulations (3D solids, 2D shells, and 3D thick shells), cohesive fracture models (commercially available in LS-DYNA 971 v6.1 and *USER_DEFINED constitutive behavior) and stacking procedures have been applied to representative composite models of increasing complexity to demonstrate their response, delamination failure modes and computational efficiency. It has been shown that stacks of 2D shell elements with nodal offsets with a user-defined constitutive model for cohesive elements can retain many of the necessary predictive attributes of delamination dominated failure while providing superior computational efficiency and flexibility required for industrial component scale design.

• Investigation of dsDNA Stretching Meso-Mechanics Using LS-DYNA

  C. A. Yuan, K. N. Chiang - National Tsing Hua University,

  This paper proposes a novel mathematical model for studying the entropic elasticity and cooperative extensibility of double strand DNA (dsDNA) using LS-DYNA and equivalent theory. Through the proposed model, the dynamic structural transitions of the dsDNA under external force/torque can be accurately simulated within an affordable CPU time. Moreover, the proposed dsDNA model comprises the meso-mechanics equivalent theory of single molecule dsDNA, including the base-stacking interaction between DNA adjacent base pairs, the Hydrogen bond of complementary base-pairs and electrostatic interactions along double-helix sugar-phosphate backbones. Good agreement is achieved between the numerical simulation and the single molecular manipulation experimental result, and the mechanical behavior of stretching nicked dsDNA could be revealed.

• Investigation of Failure Criterion in Dynamic Torsion Tests with Solid Cylindrical Specimens

  Pavel A. Mossakovsky, Fedor K. Antonov, Lilia A. Kostyreva - Moscow State University

  When investigating the limiting states of materials under dynamic loading conditions, it’s important to specify the dependency of plastic failure strain on the stress state. Usually, such dependence is build upon the experimental data obtained from dynamic tests in tension and compression of solid cylindrical specimens with different working part geometry, followed by a monotonic extrapolation. In the recent studies [1] the existence of complex, non-monotonic dependence of failure strain on the stress state parameters is shown for a number of materials. In these cases, a mentioned set of tests is not enough to construct a reliable criterion relations. In statics, one of the most informative experiments for the failure criterion construction is a torsion test on solid or thick-walled cylindrical specimens. Although a nonuniform stress state arises in the sample in this case, effective methods of its interpretation are developed [2,3]. The theory of this experiment conformably to the dynamic processes at large plastic strains has not yet been developed. Using the LS-DYNA implemented virtual test bench, the experimental setup for the solid cylinder torsion test with high strain rates and methods of its stress state identification are discussed. It is shown that for the strain rate range of 102-104 1/s the kinematic hypotheses that are taken in the quasi-static torsion are valid, that allows the effective use of known methods of the sample’s stress state decoding.

• Investigation of Improvised Explosive Device Effects on a Section Hull of Armored Military Vehicle

  İsmet Kutlay ODACI, Samet Emre YILMAZ, İlker KURTOĞLU

  Military vehicles and their occupants in conflict zones face a significant risk from improvised explosive devices (IEDs). Simulating IED risks on armored military vehicles requires employing various modeling approaches. However, to ensure the accuracy and effectiveness of these approaches, it is crucial to accurately transfer the explosive load onto the vehicle structures. This study aims to address this critical point by developing a methodology for selecting the appropriate vehicle components for load transfer and evaluating the proximity of the analysis model to live fire test results.

• Investigation of LS-DYNA Modeling for Active Muscle Tissue

  Sebastian Mendes, Dr. Chiara Silvestri, Prof. Dr. Malcolm H. Ray - Worcester Polytechnic Institute

  This study is aimed at investigating and comparing one-dimensional and three-dimensional finite element models of active muscle tissue. Skeletal muscle is a very complicated biological structure to model due to its non- homogeneous and non-linear material properties as well as its complex geometry. Additionally, forces generated from muscle activation are directly related to the muscle length and contraction velocity. Finite element discrete Hill-based elements are largely used to simulate muscles in both passive and active states. There are, however, several shortfalls to utilizing one- dimensional elements, such as the impossibility to represent muscle physical mass and complex lines of action. Additionally, the use of one-dimensional elements restricts muscle insertion sites to a limited number of nodes causing unrealistic loading distributions. These limitations are partially solved with a three-dimensional solid muscle model, where discrete Hill-based elements are combined in series and parallel to solid elements possessing hypo-elastic material properties. Despite some instability, the model was concluded to be an improvement over purely one-dimensional muscle models

• Investigation of Mechanical Behavior of Lithium-ion Battery under Loading and Suggestion of Simplified Modelling Approach

  Atsushi Takahashi, Shinichi Amano, Kei Saito, Yasuhito Aoki

  Ensuring battery safety is one of the key issues in the design of electric vehicles. In many cases, batteries are designed to be placed in strong cases or with sufficient clearance to prevent serious damage. On the other hand, to develop a vehicle which is lighter and can run longer, it is necessary to reduce the weight of battery cases and the clearance between cells. To meet the above requirements, it is important to fully understand the mechanisms leading up to the occurrence of short circuits that cause thermal runaway, and to feed such information back into the design.

• Investigation of Mesh Regularization in MAT_224 for Subsequent Use in Impact Simulations

  Troy Lyons, Kiran D’Souza (The Ohio State University)

  This work is focused on the use of mesh regularization, which is an attempt to remove the mesh dependence from finite element simulations. Mesh regularization techniques are often used to help match experimental data and allow for reduced computational cost. The MAT_224 material model within LS-DYNA® allows users to define a failure criterion that is dependent on temperature, strain rate, stress state, and element size. The element size dependence in the failure criterion can help reduce the influence of mesh size on simulated results under certain circumstances. However, some issues may arise when the MAT_224 material model is applied to different geometries, stress states, and element sizes than the regularization curve was originally created from. In this work, the conditions to best use mesh regularization are investigated, which is done with various comparisons using experimental and simulated data, both with and without mesh regularization.

• Investigation of Seat Modeling for Sled Analysis and Seat Comfort Analysis with J-SEATdesigner

  N. Ichinose, H. Yagi (JSOL)

  Recently vehicle model is becoming more detailed and complex. Due to refinement of vehicle model, automotive companies are demanding to directly evaluate dummy injury criteria in crush analysis. To evaluate injury criteria, more detailed seat model is needed, because injury criteria are highly depending on seat structure and restraint system. Seat structure consists from metal frame, foam pad, covering fabric and complex mechanism.

• Investigation of the Arbitrary Lagrangian Eulerian Formulation to Simulate Shock Tube Problems

  C.P. Salisbury, D.S. Cronin, F.S. Lien - University of Waterloo

  A critical step in modeling complex problems using numerical simulations is validating the numerical approach using simplified problems. The current study investigates application of the Arbitrary Lagrangian Eulerian (ALE) formulation, as implemented in LS-DYNA, to simulate a pseudo 1-D shock tube problem. The shock tube problem was selected since analytical results can be directly determined from the initial conditions. A shock tube is modeled as two regions of fluid at two different pressures separated by a thin membrane. The two regions are usually, but not necessarily, comprised of the same fluid. One region, know as the driver, is at a higher pressure than the other. Ideally, the thin membrane is completely destroyed to initiate flow, allowing the high pressure region to interact with the low pressure region. If the difference in pressures between the two regions is sufficient, a shock wave will propagate into the low pressure region and an expansion wave will propagate into the high pressure region. The current study is conducted to test the ability of the ALE formulation in LS-DYNA to correctly predict the shock and expansion wave propagation seen in a shock tube test. The results of this study are dependent on a number of factors such as the size and orientation of the mesh. A convergence study to determine the minimum mesh density to correctly simulate the shock phenomena was also conducted. This is of special importance when the ALE formulation is used in real world problems where the required mesh size can become quite large, and therefore computationally prohibitive.

• Investigation of the Effects of the Coil Design on Electro-Magnetic Forming of a Thin-Walled Aluminum Tubular Material

  H. Kim, P. L'Eplattenier (Edison Welding Institute), I. Caldichoury (Livermore Software Technology Corp.), J. Shang (American Trim)

  In this study, a thin-walled aluminum tube was expanded using the electro-magnetic forming (EMF) process. Two different designs of coil were developed using EMF simulations with LS-DYNA's electromagnetic module in version 980. The initial thickness of the aluminum tube was 0.254 mm (0.01 in.) and the material of the tube was Aluminum 3000 (Al-3000). This aluminum material is known to be difficult to expand more than a 9% expansion ratio at a given thickness. To evaluate the performance of the coil to expand the tube without failures, two different coils were designed and manufactured to have two different gaps between the coil and the workpiece. Preliminary simulations were conducted to determine the baseline design of the coil and after some preliminary EMF tests, the coil design was changed. Tubular samples were tested with two different coils and two different die sets (e.g., 10 and 12% expansion ratios). The EMF process was numerically modeled with LS-DYNA and the simulation results were compared with experiments.

• Investigation of the Failure Behavior of Bolted Connections under Crash Loads and a Novel Adaption to an Enhanced Abstracted Bolt Model

  Florian Schauwecker, Daimler AG, Research and Development, Sindelfingen, Germany, IFB Institute of Aircraft Design, University of Stuttgart, Germany, , David Moncayo, Dr.-Ing. Markus Beck, Daimler AG, Research and Development, Sindelfingen, Germany, Prof. Dr.-Ing. Peter Middendorf, IFB Institute of Aircraft Design, University of Stuttgart, Germany

  This study presents a new approach for the modelling of bolted joints in vehicle crash simulations with LS-DYNA®. In order to evaluate energy absorption concepts, it is essential to transfer loads between joining parts and to predict the failure behavior of threaded fasteners. For conventional models, the maximum tensile strength or the maximum elongation is considered as a failure criteria. Enhanced bolt models require the comprehension of the physics, the failure behavior as well as the corresponding numerical limitations. Experiments were conducted under three different load types, while the thread-shaft ratio, the clamping length and the bolt diameter were varied. The experimental results are utilized on one hand as a reference to validate conventional models and on the other hand as basis for more detailed models.

• Investigation of the Shear Thickening Fluid Dynamic Properties and its Influence on the Impact Resistance of Multilayered Fabric Composite Barrier

  P.A. Mossakovsky - Moscow State University, A.M. Bragov - University of Nizhniy Novgorod, M.E. Kolotnikov, F.K. Antonov - FSUE "MMPP "Salut"

  The results of experimental and computational study of properties of shear thickening fluid (STF) are observed. Two series of dynamic tests by the Split Hopkinson Pressure Bar method in rigid and soft casings are carried out to determine the dynamic bulk and shear properties of STF. A simplified mathematical model of the STF is formulated for the use in computer simulation of ballistic impact tests of multilayered fabric composite protective shells (Kevlar + STF). Numerical simulation is conducted with nonlinear LS-DYNA® code using ALE approach. The study confirmed the hypothesis about the possibility to describe STF behavior by a Newtonian fluid model in the characteristic range of strain rates. The parameters of shear viscosity and bulk compressibility of the model are defined. It is concluded that the contact interaction between STF and Kevlar basis is described by Coulomb friction law which is unnatural for fluid interactions. It is shown that the effectiveness of the STF impregnation is due to the facts of composite layers collapsing prevention and presence of internal friction.

• Investigation of the Thermal Effects of Magnetic Pulse Forming using LS-DYNA

  D. Chernikov, V. Gluschenkov (Samara State Aerospace University), P. L’Eplattenier (Livermore Software Technology Corp.)

  This paper shows the results o f LS-DYNA simulations and experimental studies of various sources of thermal effects occurring during magnetic pulse forming: theJoule heating of the eddy currents, the work of plastic deformation and the collision with the die. The obtained results allow quantifying the thermal effects and their influence on the mechanism of high-speed deformation: the technological plasticity of the forming process, the level of residual stresses during assembly operations, the mechanism of formation of welded joints, and so forth.

• Investigation on Parameter Identification and Coarse Graining Models using Discrete Element Capability in LS-DYNA

  S. Tokura (Tokura Simulation Research)

  Processes such as transportation, flowing and processing of powder materials can be seen in the manufacturing process of various industrial products and are important processes for manufacturing high quality products. Discrete Element Method (DEM)[1] is widely used as a simulation method to handle powder materials, and excellent DEM function is also implemented in LS-DYNA. The DEM model can be used intuitively, and there is an advantage that stable computation can be performed. On the other hand, the DEM model is a hypothetical model based on the spring-mass model, and in order to reproduce the real phenomenon with high accuracy, it includes many numerical parameters that the user must decide beforehand. In this paper, the simulation of a compression experiment of polymer pellets were performed and the result of the parameter identification using optimization software LS-OPT is reported. In addition, when DEM is applied to fine powder material, the number of particles becomes enormous, and in many cases it cannot be processed in a common computational environment. In such a case, a coarse graining model is used to reduce the number of particles and computational load. Various ideas have been proposed for the method of coarse graining so far, and in this paper several coarse graining models were tested to compare powder behavior in drum mixing problem.

• Investigation on Simulation of Buckling of Aluminium Sheet Alloys

  Ralf Schleich - HochschulInstitute Neckarsulm, Christoph Albiez - AUDI AG, Apostolos Papaioanu, Prof. Dr. M. Liewald MBA - Universität Stuttgart

  The lack of accuracy of buckling prediction in forming simulation is widely known. This is mainly caused by insufficient element stiffness as well as a very simplified strain path but not sheet thickness dependent buckling criterion. Within this contribution a methodology for investigating such issue is developed. This paper also reveals possibilities concerning an experimental analysis of buckling sensitivity of AA6016 aluminium sheet metal alloys. For this purpose, specimen shape referring to Yoshida which cannot be used for aluminium alloys have been enhanced simulatively. Thus, nine geometries ensuring different strain paths have been developed and validated experimentally. Based on this simulative and experimental test set up a buckling criterion for plane aluminium sheets under uniaxial tension is given here.

• Investigation on Simulation of Buckling of Aluminium Sheet Alloys

  Ralf Schleich - HochschulInstitute Neckarsulm, Christoph Albiez - AUDI AG, Apostolos Papaioanu, Prof. Dr. M. Liewald MBA - Universität Stuttgart

  The lack of accuracy of buckling prediction in forming simulation is widely known. This is mainly caused by insufficient element stiffness as well as a very simplified strain path but not sheet thickness dependent buckling criterion. Within this contribution a methodology for investigating such issue is developed. This paper also reveals possibilities concerning an experimental analysis of buckling sensitivity of AA6016 aluminium sheet metal alloys. For this purpose, specimen shape referring to Yoshida which cannot be used for aluminium alloys have been enhanced simulatively. Thus, nine geometries ensuring different strain paths have been developed and validated experimentally. Based on this simulative and experimental test set up a buckling criterion for plane aluminium sheets under uniaxial tension is given here.

• Investigation on the Dynamic Behavior of AlgoTuf 400F Steel

  G. Toussaint (Defence Research and Development Canada)

  In order to improve finite element simulation predictions of a dynamic event such as a blast or a ballistic impact on a structure, the dynamic behavior of the materials involved has to be investigated. The information gathered from this investigation can then be further used to choose the constitutive material model as well as identified its parameters. In this paper, the main objective is to share the findings from this investigation for the AlgoTuf 400F steel. The first section of the paper presents the quasi-static test that were performed by Defence Research and Development Canada (DRDC) as well as the split Hopkinson pressure bar (SHPB) tests that were performed at a strain rate between 103 and 104 s-1. These experimental data showed that at low strain rates, the material did not exhibit exactly the same behavior in the rolling direction (longitudinal direction) compared to the transverse one. It was also found that at higher strain rates, the effect of the manufacturing method on the properties through a 25.4 mm (one inch) thick plate could be neglected. Nevertheless, the material has showed sensitiveness to the strain rate and this was taken into consideration in the constitutive material model. In the second section, the plasticity parameters identified for the simplified Johnson- Cook constitutive strength model obtained using these experimental data are presented. The third section describes the 2D axisymmetric finite element (FE) model of the SHPB test and shows good agreement between numerical and experimental results. It is therefore possible in the last section to perform a parametric analysis to study the deformation response of an AlgoTuf 400F plate loaded by a spherical air blast, using the particle blast method. The next step of this investigation will be to identify a constitutive damage/failure model and get its parameters to be able to predict accurately the deformation and damage/failure response of an AlgoTuf 400F steel plate subjected to a blast event.

• Investigation on Transversal Anisotropy of an Aluminum Sheet for Crash Applications

  F. Andrade, C. Wilking, D. Koch (DYNAmore GmbH), M. Feucht (Mercedes-Benz AG)

  In this paper, we concentrate our efforts on the simulation of an aluminum sheet material used in the automotive industry. A series of experiments using samples with different geometries is performed in order to characterize the material under different stress states. Plasticity is considered using a von Mises based and a Barlat based material model (respectively, *MAT_024 and *MAT_036 in LS DYNA®). For the Barlat-based model, it is assumed that the R-values are the same for all material directions, a suitable assumption for 6000 aluminum sheets. This means that anisotropy is only present through the thickness and not in the plane of the material. In turn, this allows a more straightforward usage of *MAT_036 in complex parts for which no mapping of material directions have to be undertaken because the thickness direction for shell elements is known a priori. Comparison with experimental data (including strain fields measured with DIC) shows that this strategy leads to a somewhat better description of the material deformation observed in physical tests when compared to the predictions of the isotropic model *MAT_024. Finally, the GISSMO failure/damage model is adopted for the failure description in LS-DYNA. It is shown that the numerical results agree very well with the experiments and not only the global force-displacement curve but also the local strain fields.

• Investigations of Generalized Joint Stiffness Model in LSTC Hybrid III Rigid-FE Dummies

  Shu Yang, Xuefeng Wang - IMMI

  The joint restraint model *CONSTRAINED_JOINT_STIFFNESS_GENERALIZED in LS-DYNA® provides users a way to define stiffness characteristics for joints defined by *CONSTRAINED_JOINT_OPTION. Based on the relative angles between two coordinate systems, moments are generated according to user-defined curves. It has been defined in LSTC Rigid-FE dummy models to describe the joint behaviors at limb joints such as hip, elbow and knee joints. There are two approaches in LS-DYNA® to calculate the relative angles, incremental update (default) and total formulation (option defined in *CONTROL_RIGID). In this paper, differences of the angular calculation of the two methods were investigated. In LSTC Rigid-FE dummy models, the default (incremental update) is used for the joint stiffness model. It demonstrates the shortcoming of the incremental update method for the joint that rotates about more than one axis. Consequently, joints at elbows and wrists in the Rigid-FE dummy models are limited to a single axis rotation, which are capable to rotate along two axes in a physical hybrid III dummy. Alternatively, a modified Rigid-FE dummy model with the total formulation method defined for the joint stiffness was then suggested.

• IRIS 3 Program: Study of the Vibrations Induced by a Missile Impact on a Reinforced Concrete Structure

  N. Van Dorsselaer, T. Legaud, V. Lapoujade (DynaS+), B. Richard (Institut de Radioprotection et de Sûreté Nucléaire)

  The IRIS program (Improving Robustness assessment of structures Impacted by a large miSsile at medium velocity) consists in an international benchmark under the hospice of OECD/NEA. After two first phases of this benchmark realized in 2010 and 2012 which aimed at assessing the ability of numerical simulations to describe the experimental structural response of the mock-up when subjected to impacts, the IRIS Program is now in its third phase. The main objectives of this phase are to assess the effect of a local damage caused by a missile impact on the induced vibrations and to assess the propagation of these vibrations to other parts of the structure, especially to pseudo-equipments which are anchored on it.

• Isogeometric Analysis in LS-DYNA

  David J. Benson - UCSD

  Isogeometric analysis: finite element analysis performed using the same basis functions as in computer aided design (CAD). CAD basis functions Implementing elements for specific basis functions Desire an ability to rapidly prototype new elements

• Isogeometric Analysis in LS-DYNA®

  Attila P. Nagy, David J. Benson (Dept. of Structural Engineering, UCSD), Stefan Hartmann (DYNAmore GmbH)

  Two new areas of development of isogeometric analysis in LS-DYNA are presented. The first, which is currently available, is mass scaling. The second, which will be available sometime during the next year, is the development of efficient integration methods for trimmed NURBS, which will allow a much more direct connection between CAD and analysis in LS-DYNA. Industrial applications of both are presented. Metal stamping is one of the most cost effective manufacturing methods for producing precision parts. Isogeometric analysis, which uses the same basis functions as the CAD programs used to design the shape of the part, is an attractive alternative to traditional finite element analysis for metal stamping. Mass scaling, and the underlying stable time step estimates, that are commonly used in metal stamping simulations are presented for isogeometric analysis. Additionally, a numerical algorithm is proposed to construct efficient quadrature rules for trimmed isogeometric elements as part of the standard pre-processing step. The motivation is to overcome the proliferation of quadrature points observed in competing adaptive and tessellation-based integration approaches. The constructed integration rule is considered to be optimal in the sense that the final quadrature points and weights satisfy the moment fitting equations with the trimmed domain up to a predefined tolerance. The resulting quadrature points are in the interior of the trimmed domain and positivity of the weights is preserved. The efficiency and accuracy of the scheme is assessed and compared to competing integration techniques. Selected problems of elastostatics and elasto-plastic dynamics are used to further demonstrate he validity of the approach.

• Isogeometric Analysis in LS-DYNA R13 - key steps towards industrial applications

  S. Hartmann, L. Leidinger (DYNAmore), D. Benson, A. Nagy, M. Pigazzini, L. Li, L. Nguyen (Ansys/LST)

  Hughes et al. [1] introduced the term isogeometric analysis (IGA) in the framework of finite element analysis (FEA). Its main idea is to use the same mathematical description for the geometry as well during the design process in a computer aided design (CAD) environment as in the later analysis phase using FEA. Numerous research papers devoted to IGA have demonstrated beneficial and superior analysis properties, using higher order and higher continuity basis functions compared to standard, low order finite elements. As B-splines and non-uniform rational B-splines (NURBS) are the most widely used geometry descriptions in CAD, NURBS-based finite elements have been developed and implemented into LS-DYNA over the last few years.

• Isogeometric Analysis in LS-DYNA: Using CAD-Geometry for Numerical Simulation

  Prof. D. Benson (University of California), D. Bhalsod, P. Ho, L. Li, W. Li, A. Nagy, I. Yeh (LSTC), S. Hartmann (DYNAmore)

  In the last decade numerous research has been done in the area of Isogeometric Analysis (IGA). The intention of this rather new technology is the wish to have a stronger integration of Computer Aided Design (CAD) and Finite Element Analysis (FEA). Its basic idea is to use the same mathematical description for the geometry as well in the design process (CAD) as in the later analysis (FEA). One of the wide spread geometry description methodology in CAD-systems is the usage of Non-Uniform Rational B-Splines (NURBS) as basis functions.

• Isogeometric Analysis on Trimmed Solids: A B-Spline-Based Approach Focusing on Explicit Dynamics

  M. Messmer (TUM), L. Leidinger, S. Hartmann (DYNAmore), R. Wüchner, Prof. F. Duddeck, K.-U. Bletzinger (TUM), F. Bauer (BMW Group)

  Engineering workflows are habitually split into a modelling phase and a consecutive analysis phase, which is primarily driven by the finite element method (FEM). However, bridging the gap between design and analysis remains a sophisticated problem and may consume a vast amount of computational as well as manual operations, especially in highly iterative development processes. To avoid this major bottleneck, Isogeometric Analysis (IGA) [1] and later Isogeometric B-Rep Analysis [2] were developed. They rely on the mathematical descriptions of Computer Aided Design (CAD), such as NURBS- and B-Spline-based boundary representation (B-Rep) models. However, classical B-Rep formulations describe a solid only by its boundary faces and do neither provide any physical nor geometrical description of the interior. Therefore, the IGA concept cannot be applied to three-dimensional structures in a straightforward manner.

• Isogeometric Analysis using the *IGA_INCLUDE_BEZIER Keyword in LS-DYNA

  M. Sederberg (Coreform), M. Scott (Brigham Young University/Coreform)

  In contrast to the laborious and error-prone process of translating computer-aided design (CAD) into computer-aided engineering (CAE) models, isogeometric analysis (IGA) performs the finite element analysis (FEA) simulation directly on CAD geometry, using smooth spline basis functions. LS-DYNA is a leader in the industrial adoption of IGA, and has recently made a significant enhancement to broaden the possible use of IGA within LS-DYNA.

• Isogeometric Analysis: Introduction and Overview

  T.J.R. Hughes - The University of Texas at Austin

  Outline: Isogeometric analysis B-splines, NURBS T-splines Bezier extraction Research progress

• Isogeometric Models for Impact Analysis with LS-DYNA

  M. Montanari, N. Petrinic (University of Oxford); L. Li (LSTC)

  The advent of isogeometric analysis (IGA) opened new horizons for reducing design and optimisation costs. By employing the same mathematical formulation to describe CAD and simulation models, IGA integrates design and analysis into a new paradigm. Our work is part of a technology validation effort that aims to assess IGA for the analysis of impacts. Case studies of (i) wave propagation, (ii) model calibration and (iii) ballistic impact are presented to compare the finite element analysis (FEA) against IGA. The IGA element formulation results more expensive than traditional FEA; however, it captures travelling stress waves more accurately. This improves significantly our ability to predict the dynamic response of systems, for example, undergoing high strain-rate loadings. Unfortunately, the mathematical formulation which makes IGA more accurate does not allow discontinuities in the displacement field. This prevents, for example, a projectile to penetrate a target plate. It is argued that the physical failure can be predicted by using material models combining strain-rate-sensitive failure criteria. From an impact engineering perspective, these case studies underpin the analysis of turbine fan blades and their containment casing (Figure 1). In order to reduce the costs of analysis, this work exploits IGA analysis-ready models, that cut down the meshing costs, and LS-DYNA parallel computing capabilities.

• Issues on Gas-Fabric Interaction in Airbag Simulation Using LS-DYNA ALE

  Ning Zhang, Linhuo Shi - Toyoda Gosei North Amercia, Bruce Tzeng - Dynamax, Inc.

  Computer Aided Engineering (CAE) has been deployed to help developing effective occupant restraint systems, such as airbags, in automotive industries for decades. Until recently, control volume method, which assumes a uniform pressure and density inside airbag, is still widely adapted in most airbag applications. Control volume method allows use of simple thermodynamic equations to efficiently model airbag. Using control volume method to simulate fully deployed airbags interacting with crash dummies, such as In-Position (IP) simulation, is appropriate. However, with the stringent safety regulations for protecting occupants with widely distributed sizes and sitting positions, as well as the implementation of side and knee airbags, Out-Of-Position (OOP) simulation becomes more and more important for airbag suppliers and OEMs. In OOP simulation, airbag starts to interact with occupants long before it is fully deployed. The non-uniform distribution of gas pressure inside airbag and the highly dynamic characteristics of airbag cushion invalidate the control volume method. To address this issue, fluid-solid interaction (FSI) is implemented in various codes in different forms. The very high speed gas interacts with soft fabric in airbag simulation is quite a challenge for conventional Computational Fluid Dynamic (CFD) codes, and special treatment to deal with this FSI problem should be carefully planned and developed. Arbitrary Lagrangian Eulerian (ALE) approach from LS-DYNA provides a possibility to model this multi-phrase highly dynamic problem. For OOP simulation, the ALE should be computationally efficient with acceptable accuracy. Normally, gap between layers of airbag is about the same order of magnitude of fabric thickness for flat or folded airbag model. To be computationally efficient, the size of Eulerian elements should be much larger than the fabric gap. This introduces the difficulty for code to handle gas-fabric interaction properly. Larger Eulerian element size slows down the gas propagating speed and causes discrepancy between simulations and testing for airbag deployment. Properly use of initial volume fraction definition from LS-DYNA to introduce gas into cushion fabric gap at time zero, can improve the results without using ultra small Eulerian elements for flat airbag model. However, for folded airbag, the application of initial volume fraction is not so successful. In present study, issues using ALE for airbag simulation will be investigated using several simple test cases. Recommendations for further improving the ALE code for airbag OOP simulation are presented.

• Itanium®– a viable next-generation technology for crash simulation?

  Adrian Hillcoat - Hewlett-Packard Ltd Bracknell, UK

  In the area of crash simulation, LS-DYNA has traditionally been a good application for measuring performance of leading computer architectures. This paper considers the architectural design of the Intel Itanium® processor, as well as the system architectures into which Itanium fits, with the purpose of understanding the benefits of the novel 64-bit EPIC architecture over and above conventional 64-bit RISC architectures as well as 32-bit Intel XEON processor architectures. The paper will provide details of LS-DYNA performance results achieved using distributed memory parallel execution. It will conclude with a look into the future to predict what might be achievable with further generations of this processor architecture for crash codes.

• J-Composites/Compression Molding - Introducing New Simulation System for FRP Composites

  Shinya Hayashi, Shaun Dougherty, Shinya Hiroi, Yoshida Atsushi (JSOL Corporation)

  Composite materials like fiber reinforced plastics (FRP) are becoming more widely used in the automotive industry and have been found very effective in reducing vehicle weight. Recently, discontinuous long carbon fiber reinforced plastics are increasingly used for lightweight structural parts with high stiffness, strength and energy absorption performance. Compression molding is considered one of the most efficient manufacturing processes to mass produce FRP parts for automotive applications. Compression molding can form discontinuous long fiber reinforced plastics into complex shapes with relatively low manufacturing cost and short process time. LST and JSOL developed new compression molding simulation techniques for discontinuous long fiber reinforced plastics using a beam-in-solid coupling function in LS-DYNA®. Then JSOL developed a modelling tool called J-CompositesⓇ/Compression Molding to generate an input deck for this new compression molding simulation. In this paper, main features of J-Composites/Compression Molding are introduced and the latest compression molding simulation result of a large scale component model created by J-Composites/Compression Molding is presented.

• J-Composites/Compression Molding Version 2.0: New Simulation Tool for CFRP Composites

  S. Hayashi, S. Dougherty, S. Hiroi, S. Wang, Y. Atsushi (JSOL)

  Composite materials like fiber reinforced plastics (FRP) are becoming more widely used in the automotive industry and have been found very effective in reducing vehicle weight. Recently, discontinuous long carbon fiber reinforced plastics are increasingly used for lightweight structural parts with high stiffness, strength and energy absorption performance. Compression molding is considered one of the most efficient manufacturing processes to mass produce FRP parts for automotive applications. Compression molding can form discontinuous long fiber reinforced plastics into complex shapes with relatively low manufacturing cost and short process time. LST and JSOL developed new compression molding simulation techniques for discontinuous long fiber reinforced plastics using a beam-in-adaptive EFG coupling function in LS-DYNAⓇ. Then JSOL developed a modelling tool called J-CompositesⓇ/Compression Molding to generate an input deck for this new compression molding simulation. In this paper, new functions of J-Composites/Compression Molding Version 2.0 are introduced and two compression molding simulations using hybrid lay-up composites are presented.

• Jet Engine Fan Blade Containment using Two Alternate Geometries

  Kelly Carney, Mike Pereira, Duane Revilock - NASA Glenn Research Center, Paul Matheny - Florida Turbine Technology

  In the rare event of a fan blade separation, the fan blade must not penetrate the case of a commercial jet engine. Due to this requirement the fan case is the heaviest single component of a jet engine. With a goal of reducing that weight, a simulation of a fan blade containment system was tested at the NASA GRC Ballistic Impact Lab and analyzed using LS-DYNA. A fan blade simulating projectile was shot at two alternate geometric containment case configurations. The first configuration was a flat plate which represents a standard case configuration. The second configuration had a surface curved outward from the projectile. The curved surfaced forces the blade to deform plastically, dissipating energy before the full impact of the blade is received by the plate. The curved case was thus able to tolerate a higher velocity of impact before failure. The LS-DYNA analytical model was correlated to the tests and a weight savings assessment was performed.

• JFOLD - Introducing A New Simulation-Based Airbag Folding System for LS-DYNA®

  Shinya Hayashi (JSOL Corporation)

  Computer simulation is playing an increasingly important role in the design, development and application of airbag safety systems. As folding patterns and airbag structures become more and more complex, users are turning to simulation based folding solutions to generate accurately folded models in a short space of time. To meet this demand, a new software tool called JFOLD has been developed by JSOL Corporation to enable successful airbag folding using LS-DYNA. JFOLD’s intuitive and interactive system guides the user through the folding steps using flow-chart graphics, interactive tool positioning/resizing, tool motion control, animation preview and so on. JFOLD runs inside the powerful and popular pre-processor Primer.

• Joint Analytical/Experimental Constitutive and Failure Model Development

  P. Du Bois (Consultant); J. Seidt (Ohio State University)

• Jones-Wilkens-Lee (JWL) Equation of State with Afterburning

  Leonard E Schwer (Schwer Engineering & Consulting Services)

  The standard Jones-Wilkens-Lee equation-of-state for modeling detonation of high explosives was modified to allow inclusion of the additional energy associated with afterburning of fuel rich (oxygen poor) high explosives. Three options are available for including the additional afterburning energy: 1. Constant energy rate addition 2. Linear energy rate addition 3. Miller Extension The performance of the afterburning equation of state is demonstrated via comparison with three experimental and numerical examples: 1. LLNL HEAF Tests, Kuhl et al. (1998): 2. NCEL Tests, Keenan and Wager (1992): 3. Moby Dick Test, Miller & Guirguis (1993)

• JSD - Introduction of Integrated Seat Design System for LS-DYNA®

  Noriyo Ichinose (JSOL Corporation)

  Recently vehicle modelling is becoming more detailed and complex. Automotive companies are more and more directly evaluating dummy injury criteria in crash analysis. To evaluate injury criteria, a more detailed seat model is needed, because injury criteria are highly depending on seat structure and restraint system. In addition to the above, many types of LS-DYNA analysis are carried out during one seat design process (e.g. frontal impact, side impact, whiplash, and so on). Because these analyses use different dummy models, different loading conditions and sometimes different dummy/seat positions, the engineer needs to understand all regulations and make a big effort to prepare the input data. To reduce this effort in the demand for more detailed seat models, an integrated seat design system named JSD has been developed.

• Keep the Material Model Simple with Input from Elements that Predict the Correct Deformation Mode

  Prof. T. Tryland (Sintef Raufoss Manufactu­­ring), T. Berstad (Norwegian University of Science and Technology)

  The 64 km/h frontal offset test is run with a deformable barrier, and the first numerical model of this barrier was made with solid elements to represent the honeycomb blocks. However this required development of a special element formulation to handle the severe deformation of the solid elements together with a special material model that could be calibrated to handle the extreme anisotropy. It is herein important to notice the amount of work, the uncertainties with the test specimens and the test procedure to get a proper representation of the honeycomb material.

• Key Parameters in Blast Modeling Using 2D to 3D ALE Mapping Technique

  Anil Kalra, Feng Zhu, King H Yang, Albert I King (Wayne State University)

  A numerical simulation is conducted to model the explosive detonation and blast wave propagation in the open air field. The mesh size and boundary conditions as well as size of air domain are the sensitive variables which may significantly affect the predicted pressure wave magnitude and rising time in blast simulations. The current approach focuses on determining the optimal key parameters to predict the blast wave accurately. A 2D to 3D mapping is performed to save the computational time. The blast induced high pressure waves are generated using the Arbitrary Lagrangian-Eulerian (ALE) formulation in the 2D domain and then mapped into a 3D space. The simulation results show that the aforementioned parameters govern pressure wave form in both 2D and 3D cases. A two-step mesh sensitivity study is performed: A parametric study is first conducted in the 2D air domain and then followed by a second one in the 3D domain while using 2D to 3D mapping. After that, as a case study in the biomedical applications, an anatomically detailed pig head finite element model is integrated with the 3D air domain to calculate the pressure gradient change inside the brain due to blast wave. The model predictions are compared with the experimental data and it has shown that the modeling strategy used can capture the biomechanical response of the surrogate with reasonable accuracy and reduced computational cost.

• Laminated Amorphous Polymers Subjected to Low-Velocity Impact

  A. Rühl, S. Kolling (TH Mittelhessen); J. Schneider (TU Darmstadt); B. Kiesewetter (Evonik Industries)

  The substitution of conventional glass products by polymeric structures bears a huge weight reduction potential for the automotive and aviation industry. Against this background, a polymeric laminate consisting of poly(methyl methacrylate) (PMMA) and thermoplastic polyurethane (TPU) was investigated experimentally and numerically with regard to its impact behavior and applicability. Basic experiments with PMMA and TPU were used to identify the thermomechanical characteristics of the monolithic materials. Furthermore, PMMA-TPU-PMMA laminates were subjected to impact loadings at velocities up to 5m/s using three-point bending and dart impact tests. The principle behavior, characterized by a distinct post-breakage capacity, was examined. A significant heating of the highly strained interlayer was measured in the post-breakage phase. Based on the experimental basis, different material models for the Finite Element simulation are presented. These material models are able to capture the temperature and time dependent behavior of the laminate. Further studies regarding modeling techniques for characteristics of laminated structures were conducted. A final validation experiment, consisting of head-dummy impacts at 10m/s on automotive side windows, was conducted for PMMA and the laminate to investigate their applicability as glass substitution products. The corresponding simulations showed very high agreement to experimental results and exhibited as reliable prediction tools for future developments.

• LANDMINE PROTECTION OF ARMOURED PERSONNEL CARRIER M113

  Mads Berg Larsen, Niras Demex, Kasper Cramon Jorgensen

  This paper presents numerical analysis and full-scale test of a mine protected armoured personnel carrier M113 subjected to a detonation of a buried 5.56 kg C4 surrogate mine placed under the belly of the vehicle. The protection consists of granulated ceramics (CRUSHMAT) filled within the space between the bottom plate and a reinforced floor. The vehicle structure and mine protection are modelled with Lagrange elements and the mine and surrounding air with ALE elements. CRUSHMAT is modelled using material model 63 Crushable foam, where stress-strain behaviour is obtained with laboratory tests.

• Large Scale Normal Modes and PSD Analysis with Nastran and LS-DYNA

  George Laird (Predictive Engineering)

  From its conception in 1976, LS-DYNA has become a world-renowned analysis code used for the simulation of complex, real-world problems. Its power stems from the simple fact that it was written early on with an eye toward harnessing the resources of a variety of computational platforms. This strategy has allowed LS-DYNA to solve large scale, multi-physics problems that were impossible just a few years ago. LS-DYNA developers have also been extending its classically nonlinear, scalable solution sequences to that of large scale, linear dynamics problems using an MMP (Massive Parallel Processing) approach. Benchmark solutions are provided showing how LS-DYNA handles the basic linear normal modes analyses using standard finite elements (beams, plates, solids and rigid links) with a comparison to an industry standard Nastran solver. Results are then presented showing how LS-DYNA multi-CPU scaling decreases solution times for the power spectral density (PSD) analysis of large scale FEA models having millions of DOFs.

• Laser impact modelling in order to assess composites bonding on aeronautical structures

  C. Michel, V. Lapoujade, T. Maillot, J. Grassy (DynaS+)

  Massively used in aeronautical structures, composites are nowadays essential in the search for a more ecological and successful industry. Their low density enables weight reduction and then decreases airplanes consumption. However, the current composites assembly process represents a limitation in their use. In fact, we do not have any reliable, industrialized and non-destructive technology to control the adhesive quality. Then composites are also riveted which adds weight and drilling process during which fibres can be locally damaged. For about 10 years, the LASAT (Laser adhesion test) technology appears to be a promising alternative. The laser impact creates a plasma that induces shock waves propagation in the structure. The LASAT technology can also be used to generate damage anywhere in the assembly thickness. The experimental technology is mature but is lacking a numerical tool so to calibrate the input laser parameters depending on the targeted results.

• Latest advancements for IGA model creation with ANSA

  L. Rorris, I. Chalkidis (BETA CAE Systems)

  During the last two years, ANSA, the leading preprocessor for crash analysis, has been heavily involved supporting the IGA community, helping create IGA models and Hybrid FE-IGA full vehicle crash models. In doing so we a set a dual target. First, advance and explore all needed technologies which are mainly new and mostly in academic research phase. Second, bring in, industry expertise in making these technologies robust and well suited for production, both in terms of stability and performance, but also in terms of data interoperability and adaptation to the highly automated process flows that characterize current automotive crash procedures. The cooperation with the ANSYS LST team has been very fruitful and rewarding. These latest developments in the pre-processor side are presented in this presentation.

• Latest ANSA developments for IGA modeling

  Lambros Rorris, Ioannis Chalkidis

  During the last years the capabilities of both LS-DYNA and ANSA are in continuous progress in terms of creating and analyzing IGA models, especially in crash and safety discipline. Automotive industry studies the behavior of ever more complex mechanical parts by running simulations using both FEA and IGA within a context where robustness and automation are probably the most important keywords. Pre – processing such parts with Isogeometric Analysis gives more accurate results in terms of displacements but robustness is yet to come. Describing and analyzing the parameters of an IGA simulation singularities, plays an important key role in the latest developments of the ANSA pre – processor, opening the way to study new models of high complexity and build hybrid models.

• Latest Development in Oasys PRIMER
• Latest Development in Oasys PRIMER
• Latest Development of the advanced Pedestrian Legform Impactor CAE Model

  C. Kleessen, C. Shah (Humanetics)

• Latest developments in Automotive Aerodynamics Using LS-DYNA ®

  Iñaki Çaldichoury, Facundo Del Pin, Rodrigo Paz (LSTC)

  LS-DYNA® is a general purpose explicit and implicit finite element program used to analyse the non-linear dynamic response of three-dimensional solids and fluids. It is developed by Livermore Software Technology Corporation (LSTC). A module to simulate incompressible flows has been added to LS-DYNA® for coupled fluid/mechanical/thermal simulations (ICFD solver). It offers a response to the ever increasing need of engineers in the automotive industry sector and elsewhere to comprehend and solve complex highly nonlinear problems involving multiple domains of physics. However, if the ICFD solver is to become a viable proposition in automotive aerodynamics, it must demonstrate its ability to accurately reproduce the elementary phenomena observed on simple geometric forms in the wind tunnel. With this objective in mind, the present paper will show for different wind speeds what results can be obtained on widely studied simplified car geometry, the Ahmed body, focusing on the complex 25 ° slant degree case.

• Latest developments in Crash Pre Processing and Post Processing. Innovative Ideas brought to the Industry with ANSA and μETA.

  L. Rorris, D. Siskos, Y. Kolokythas - BETA CAE Systems SA

  The increasingly demanding and complex requirements in Crash Analysis, require continues and innovative software development. BETA CAE Systems in an effort to meet, and exceed, the demands of the industry is introducing new cutting edge technologies. Both in the pre processing area with ANSA, and in post processing with μETA. This paper presents these new technologies. With the introduction of a new version of ANSA in 2009 a new user interface was presented. The new interface is a long term effort to give the CAE engineer the capacity to work in a modern software interface environment leading in increased productivity and “ease of use”. On the same time the development of highly specialized tools can greatly reduce the time of pre processing by automating various difficult operations. Some of these are a kinematic solver that allows the manipulation of complex kinematic mechanisms of crash models and tools that automate the procedures for occupant and pedestrian testing. In the area of post processing the advances are equally impressive in the latest μΕΤΑ versions. Better system resources utilization such as smaller memory footprint and a huge speedup in graphics performance, guarantee that the responsiveness and feel of the software environment won’t be compromised even by the biggest models. Additionally advanced functionality, like the direct calculation of section forces, provides the tools that are needed for the evaluation of the results. Recently process automation tools are introduced which together with advanced report generation functionalities make the automation of post processes easy.

• Latest developments in Crash Pre Processing and Post Processing. Innovative Ideas brought to the Industry with ANSA and μETA.

  L. Rorris, D. Siskos, Y. Kolokythas - BETA CAE Systems SA

  The increasingly demanding and complex requirements in Crash Analysis, require continues and innovative software development. BETA CAE Systems in an effort to meet, and exceed, the demands of the industry is introducing new cutting edge technologies. Both in the pre processing area with ANSA, and in post processing with μETA. This paper presents these new technologies. With the introduction of a new version of ANSA in 2009 a new user interface was presented. The new interface is a long term effort to give the CAE engineer the capacity to work in a modern software interface environment leading in increased productivity and “ease of use”. On the same time the development of highly specialized tools can greatly reduce the time of pre processing by automating various difficult operations. Some of these are a kinematic solver that allows the manipulation of complex kinematic mechanisms of crash models and tools that automate the procedures for occupant and pedestrian testing. In the area of post processing the advances are equally impressive in the latest μΕΤΑ versions. Better system resources utilization such as smaller memory footprint and a huge speedup in graphics performance, guarantee that the responsiveness and feel of the software environment won’t be compromised even by the biggest models. Additionally advanced functionality, like the direct calculation of section forces, provides the tools that are needed for the evaluation of the results. Recently process automation tools are introduced which together with advanced report generation functionalities make the automation of post processes easy.

• Latest Developments in Crash Pre Processing and Post Processing - Innovative Ideas Brought to the Industry

  L. Rorris - BETA CAE Systems SA

  The increasingly demanding and complex requirements in Crash Analysis, call for continuous and innovative software development. BETA CAE Systems in an effort to meet and exceed the requirements of the industry is introducing new cutting edge technologies, both in the pre-processing area with ANSA, and in post-processing with μETA. This paper presents these new technologies. With the introduction of a new version of ANSA in 2009 a new user interface was presented. The new interface is a long-term effort to give the CAE engineer the capacity to work in a modern software interface environment leading in increased productivity and “ease-of-use”. Taking the burden of the hard pre-processing tasks away, it allows the user to take full advantage of the solvers capabilities. The effort is ongoing and further enhancements and developments throughout 2010 and the 13.x versions will lead to a totally new user workflow. At the same time, the development of highly specialized tools can greatly reduce the re- processing time by automating various difficult operations. A characteristic example is the introduction of an integrated multi-body solver that allows the manipulation of complex kinematic mechanisms of crash models (i.e. suspensions, seats, dummies, roof tops etc.). In the field of occupant and pedestrian safety, advanced tools that automate the procedures of target identification and impactor positioning allow the easy creation of corresponding load cases. Additionally, these tools give the possibility of further analysis types such as Robustness Analysis. In the area of post-processing, the advances are equally impressive in the latest μΕΤΑ versions. Better utilization of system resources, such as smaller memory footprint and a huge speedup in graphics performance, guarantee that the responsiveness and feel of the software environment won’t be compromised even by the largest models. Additionally, advanced functionality, like the direct calculation of section forces, provides the tools that are needed for the evaluation of the results. Recently, process automation tools are introduced, which together with advanced report generation features make the automation of post-processing much easier.

• Latest FE Model Development of THOR-50M Crash Test Dummy

  Ismail Maatouki, Humanetics Europe GmbH, Heidelberg, Germany;, Stephen Fu, Zaifei Zhou, Humanetics Innovative Solutions, Inc. Farmington Hills, MI (USA)

  THOR-50M LS-DYNA® Finite Element (FE) dummy model, developed by Humanetics (Humanetics Innovative Solutions, Inc.), has been widely used in occupant safety by OEMs and suppliers and has proved to be a mature model since its first release in early 2014. In the next two years, major development work had been completed, including material characterization, component validations, sled test validations and robustness verifications.

• Latest in AI/ML application to modeling complex geometry

  P. Krishnaswamy, U. Mallikarjunaiah (Xitadel), Y. Nakagawa (Honda)

  There is rapid convergence of multiple technologies that are creating unprecedented capabilities in every field of technology. The incorporation of new technologies like Artificial Intelligence/Machine Learning (AI/ML) in the CAE process has been quite gradual. Xitadel’s XIPA technology is a pioneering effort to leverage the power of ML to transform the CAE model build process and bring this to production level. CAE modeling is a critical path in the overall CAE process. CAE modeling however is very time consuming, particularly because plastic subsystems typically contain multiple complex features and variable thicknesses.

• Layout, Validation and Benchmark of an all new Frontal Offset Barrier FEM Model

  Bernhard Fellner - Magna Steyr Fahrzeugtechnik AG & CoKG, Thomas Jost - Das Virtuelle Fahrzeug Forschungsgesellschaft mbH

  For the customer, passive safety is one of the driving reasons for the decision when buying a new car. To ensure high safety standards, passive safety is demonstrated in vehicle crash tests. Instead of vehicle to vehicle crash tests, one vehicle is replaced by an aluminium honeycomb based crash barrier. This barrier represents the front of a vehicle by the shape, the deformation behaviour and the energy absorption. Using Finite Element Method (FEM) it is possible to show and predict the behaviour of the vehicle’s structure during a previous mentioned crash test. To ensure good simulation results compared to reality it is not only necessary to correctly build up the FE model of the vehicle, but to simulate the real behaviour of the crash barrier too. Experience shows that the deformation behaviour of the FEM crash barrier seriously influences the quality of the full vehicle simulation. The barrier models that are currently in use, show insufficient reliable results. The modelling techniques are not able to show the principle deformation and failure behaviour of aluminium honeycomb. Moreover huge barrier deformation is able to cause serious instability problems of the models. That leads to an inaccuracy in predicting the vehicle safety during a virtually based development process. It has to be considered that CAE driven design processes are only feasible when the simulation delivers results with reliable prognosis quality. During the last years a new modelling method for aluminium honeycomb structures especially based on the IIHS side impact barrier was developed. In the meanwhile the method proved to work also with the high relative deformations that have to be faced in a frontal offset crash test. A very specific sequence of tests was carried out to determine the structural properties of the aluminium honeycomb, the cladding and the whole barrier itself as well. The tests were planned to show the reproducibility of the results but also for example the dependence on the test velocity at the same energy levels. The output of this process is a stable barrier model capable to show localized deformations. This prevents overestimation of energy absorption by distributing the deformation on the whole barrier. The developed method to simulate crash barriers contributes to the improvement of full vehicle crash simulations. Reliable calculation results based on more accurate barrier models will help to reduce the risk of changes in already released toolings after analysing first real crash results.

• Layout, Validation and Benchmark of an all new Frontal Offset Barrier FEM Model

  Bernhard Fellner - Magna Steyr Fahrzeugtechnik AG & CoKG, Thomas Jost - Das Virtuelle Fahrzeug Forschungsgesellschaft mbH

  For the customer, passive safety is one of the driving reasons for the decision when buying a new car. To ensure high safety standards, passive safety is demonstrated in vehicle crash tests. Instead of vehicle to vehicle crash tests, one vehicle is replaced by an aluminium honeycomb based crash barrier. This barrier represents the front of a vehicle by the shape, the deformation behaviour and the energy absorption. Using Finite Element Method (FEM) it is possible to show and predict the behaviour of the vehicle’s structure during a previous mentioned crash test. To ensure good simulation results compared to reality it is not only necessary to correctly build up the FE model of the vehicle, but to simulate the real behaviour of the crash barrier too. Experience shows that the deformation behaviour of the FEM crash barrier seriously influences the quality of the full vehicle simulation. The barrier models that are currently in use, show insufficient reliable results. The modelling techniques are not able to show the principle deformation and failure behaviour of aluminium honeycomb. Moreover huge barrier deformation is able to cause serious instability problems of the models. That leads to an inaccuracy in predicting the vehicle safety during a virtually based development process. It has to be considered that CAE driven design processes are only feasible when the simulation delivers results with reliable prognosis quality. During the last years a new modelling method for aluminium honeycomb structures especially based on the IIHS side impact barrier was developed. In the meanwhile the method proved to work also with the high relative deformations that have to be faced in a frontal offset crash test. A very specific sequence of tests was carried out to determine the structural properties of the aluminium honeycomb, the cladding and the whole barrier itself as well. The tests were planned to show the reproducibility of the results but also for example the dependence on the test velocity at the same energy levels. The output of this process is a stable barrier model capable to show localized deformations. This prevents overestimation of energy absorption by distributing the deformation on the whole barrier. The developed method to simulate crash barriers contributes to the improvement of full vehicle crash simulations. Reliable calculation results based on more accurate barrier models will help to reduce the risk of changes in already released toolings after analysing first real crash results.

• Learning Module for using Dynaform® to Study the Effects of Die-Entry and Punch-Nose Radii on Drawing Cups

  W.K. Waldron, R. Echempati, C.J. Hoff, P. Zang - Kettering University

  The new model for an entry-level engineer in the United States automotive industry is that of a design engineer, one who is capable of part design and analysis using advanced CAE tools such as solid-modeling, mechanical systems dynamics (MSD), finite element analysis (FEA), and computational fluid dynamics (CFD). Since this will require a major change and enhancement of the current undergraduate engineering curriculum, the Mechanical Engineering Department at Kettering University (formerly GMI) is developing a comprehensive set of Learning Modules that can be woven into all Mechanical Engineering courses so that students use the tools often and in various contexts to solidify their knowledge of the computational tools and meet the learning objectives of the courses. The modules will be self-paced and self-explanatory, can be used by students and faculty outside of the classroom, and include meaningful examples that use CAE and existing laboratories to study real-life problems. This paper describes one of the first prototype modules for Manufacturing and Mechanical Engineering students in a senior-level course in sheet metal forming. The students investigated the effects of changes in the die-entry radius and punch-nose radius versus depth of draw for cylindrical cups using various ring dies and flat bottom punches. The experimental data consistently showed that the die-entry radius has a very marked effect on depth while the punch-nose radius has very little effect. For a change in die-entry radius, once a minimum value has been exceeded, the material flows smoothly over the radius to generate a full depth cup. Simulation results using Dynaform® are presented that show that the experimental observations can be modeled by assigning appropriate values for the process parameters (die entry radius, clearance, friction, and binder). The Design of Experiments (DOE) method is used to develop guidelines for the selection of the process parameters for drawing cylindrical cups based on Forming Limit Diagrams from the simulations data.

• Lenovo Solution for Engineering Analysis.pdf
• Leveraging LS-DYNA Explicit and Implicit on Latest Intel Technologies

  N. Meng (Intel), J. Wang, R. Lucas (LSTC)

  In this paper we discuss Intel’s continued optimization efforts with LS-DYNA® and demonstrate the impact of new Intel technologies. Two different approaches to exploit Intel® Advanced Vector Extensions 512 (AVX-512) are shown: LS-DYNA® Explicit using Intel compiler vectorization techniques and LS-DYNA® Implicit using Intel® Math Kernel Library (MKL) for accelerating dense matrix computational kernels. Numerical accuracy of simulation results for LS-DYNA® Explicit comparing Intel® SSE2 and Intel® AVX-512 is also explored. Finally, we reveal the benefits of Intel® Optane™ DC Persistent Memory technology for LS-DYNA® Implicit simulations. For our studies we used the Topcrunch benchmarks, ODB-10M & car2car models, for LS-DYNA® Explicit and AWE benchmarks, CYL1E6 & CL2E6 models, for LS-DYNA® Implicit

• Li-Ion Battery Modeling Strategies for Electric Vehicle Crash Applications

  Matthieu Seulin, Charlotte Michel, Vincent Lapoujade, DynaS+, Toulouse, France;, Pierre L’Eplattenier, LSTC, Livermore, CA, USA

  In the automotive field, car manufacturers currently face a revolution in terms of energy sources to power vehicles. The combination of electric engines and Li-Ion batteries is an efficient solution to solve environmental issues, and its usage is expected to grow in the future. Nevertheless, this technology may present some serious hazards which origins are different than the thermal engines ones. The Li-Ion batteries are generally located all along the floor chassis and the car center of gravity is then lowered compared to other vehicles. Consequently, the safety concerns to investigate are different than usual. The short-circuit represents the greatest risk among the potential dangers observed when crushing the battery. Several physical domains (mechanics, electromagnetics and thermal) are involved, resulting in a thermal runaway that might lead to an explosion

• Limitations of Smeared Crack Models for Dynamic Analysis of Concrete

  Y. S. Khoe, J. Weerheijm (TNO)

  Performance prediction of concrete structures under explosive loadings or impact is an essential part of the research that is being performed within TNO. One of the current research topics is the explosive safety of tunnel structures. In the context of this research we evaluate the capabilities and limitations of concrete material models in LS-DYNA. The evaluation focuses on the CSCM concrete model and in particular the damage and failure characteristics of the model under single and sequential compression and tensile loading. Like many existing concrete models, the CSCM uses a smeared crack approach to model the reduction in strength of damaged concrete. It will be shown that the smeared crack approach has an intrinsic limit that places a restriction on the minimum size of an element. Furthermore, it is predicted that the built-in fracture energy regularization further aggravates the situation. The regularization algorithm tries to maintain a constant fracture energy. When elements have a size that is smaller than the limit size, the fracture energy of the total structure is increased which causes non-physical behavior. The predictions are confirmed by analyses on a tunnel structure as well as analyses on concrete cylinders under tension and compression. In contrast to the established minimum width, high dynamic loads or very local loads such as explosions or impact require a very fine mesh that can accurately describe the stress state and the shockwaves that are induced during these events. Using a reference load of a BLEVE explosion, the desired element size is derived and it will be shown that the desired element size is far smaller than the lower limit of element size. The consequences of the conflicting restrictions on the element size by the material model and the dynamic loading are illustrated by the tunnel structure analysis.

• Linux Cluster Compute Power Out of the Box

  Harry Schlagenhauf - science+computing

• Lithium-Ion Battery Models and Thermal Management in LS-DYNA

  K.-S. Im, Z.-C. Zhang, G. Cook Jr. (LSTC)

  We have developed two Lithium-ion battery models in LS-DYNA®: i) a single insertion lithium metal model, and ii) a dual insertion composite model. Our models are intended to assist users in tackling problems ranging from the fundamental battery cell physics to very complex situations such as thermal management (TM) of electric vehicle (EV), and eventually, battery-structure-interaction (BSI) problems. The battery models in LS-DYNA® are based on the following multiphysics aspects: 1) thermodynamics, 2) kinetics, and 3) transport. In thermodynamics, the role of electrochemical potential, which is the driving force in the concentrated solution will be discussed, and an example will be provided as to how to set up the open-circuit potential card in the keyword input. Detailed presentation of Bulter-Volmer kinetics illustrates how to correctly evaluate the surface overpotential at the interface between electrode and electrolyte, and also the pore-wall flux from the insertion materials in compsite electrodes. In addition, comprehensive keyword set up for the transport properties in both aqueous and polymer electrolyte will be provided, including the concentrated material transport theory. For the thermal treatment of the battery model, we have coupled with existing thermal solver and structure solver and thus, we will present a keyword example showing how to simulate a thermal problem in a battery cell stack, module and pack in the practical scaled-up EV application. Finally, we will provide the future development plan to handle more complex problems confronting the battery related industries by using BSI solver in LS-DYNA®.

• Lithium-Ion Battery Multi-Physics Simulations Using LS-DYNA®

  Jie Deng, Chulheung Bae, Theodore Miller, Min Zhu (Ford Motor Company), Pierre L’Eplattenier, Inaki Caldichoury (Livermore Software Technology LLC)

  The market share of electrified vehicles grows rapidly in recent years. One of the top priorities in the electrified vehicle design is to improve the robustness of lithium-ion battery system during a crash. Various abuse tolerance tests have been developed to evaluate the performance and robustness of lithium-ion batteries. These tests can be resources intensive, and in some cases, provide limited information on the failure mechanisms of batteries. As such, computational modeling becomes an important tool to evaluate the battery under different abuse scenarios. Here we present a multi-physics battery model that can predict coupled mechanical, thermal, electrical and electrochemical responses of automobile lithium-ion batteries under abusive conditions. In this model, the electrochemical behavior of batteries is described by a spatially distributed equivalent circuit model, where polarization and damping effects are captured by a resistance-capacitance network. During simulations, the mechanical solver predicts the onset of short circuit, and then the coupled thermal, electrical and electrochemical solver captures the evolution of temperature, voltage and current distribution after short circuit initiation. In order to make the proposed model applicable to module or pack level simulations, various element formulations and strategies have been developed to improve computational efficiency without scarifying much accuracy. Details of model set up, parameters evaluation, and case studies that demonstrate the model capabilities will be presented. Experimental validation of model prediction and the future development of this framework will also be discussed.

• Load Balancing Update

  Brian Wainscott (LSTC)

  One of the keys to efficient parallel processing is having an evenly distributed workload so that every processor has the same amount of work to do. Because there are unavoidable synchronization points in the simulation process, when one processor has more work then the other processors will have to wait, which wastes CPU time. LS-DYNA® has many options available for controlling the initial distribution of elements to processors to help achieve a good load balance. Unfortunately, for many simulations the distribution of work changes during the run. This can make it nearly impossible to have a good load balance over the whole simulation with a static decomposition. The capability to move nodes and elements between processors during the simulation to maintain good load balance has been under development for some time. The current state of this ongoing work is presented.

• Load Case Preference Patterns based on Parameterized Pareto-Optimal Vehicle Design Concept Optimization

  S. Ramnath (Ohio State University), N. Aulig, M. Bujny, S. Menzel (Honda Research Institute Europe), I. Gandikota (LSTC), K. Horner (Honda R&D Americas)

  Classical Topology Optimization (TO) methods aim to optimize the distribution of material within a design space for one given objective function and constraints. However, in the vehicle design process, there are many different load cases and several different objectives. Among them maximizing stiffness of components for regular working conditions, and maximizing energy absorption in exceptional loading conditions, for instance in crash events, are important. Recently, the Scaled Energy Weighting Hybrid Cellular Automata (SEW-HCA) [1], [2] method was adopted in LS-TaSC™. The SEW-HCA is a practical multidisciplinary TO approach for devising concept structures based on the intuitive choice of preferences leading to the desired trade-off between crash performance and stiffness. In this paper, we propose an integration of the SEW-LS-TaSC method into LS-OPT® to perform a design of experiments (DOE) on the load case preference parameters. The integration into LS-OPT® results in a convenient user interface that facilitates application in an industrial development process with non-expert users. This integration enables quick studies on many different concept designs based on preference samples generated by the DOE. The results from the sensitivity analysis provide data for a better understanding of the influence of load case preferences on the design space. By comparing the performance of structures obtained for different load case preferences, the user will be able to find a desired trade-off solution within the concurrent optimization runs. For further development, the proposed LS-OPT® workflow can potentially include 1) NVH load cases as additional discipline and 2) optimizations of other topology optimization hyperparameters for further concept exploration.

• Looping Formation During Colonoscopy A Simulation

  Charles R. Welch, John D. Reid (University of Nebraska-Lincoln)

  A simulation of a loop formation during colonoscopy is attempted using LS-DYNA . The tissue is comprised of a Mooney-Rivlin rubber model adjusted iteratively to somewhat match raw force-displacement data of small intestine tissue. After finding adequate parameters for friction and damping coefficients, the scope is advanced into a colon model in the simulation and loop formation appears. Whether the loop formation obtained through simulation is realistic remains to be determined due to lack of good test data.

• Low Risk Deployment Passenger Airbag – CAE Applications & Strategy

  Bill Feng (Jaguar Land Rover)

  Occupants who were out-of-position (OOP) in the vehicles would increase the risk of airbag induced injuries in the crash event. The punch out forces resulting from the airbag deployment act on the occupant and would cause potential injuries. To evaluate the OOP performance of the airbag system, FMVSS208 requests a series of test loadcases. In passenger side OOP, it includes test loadcases with rear-facing child seats, 3yld and 6yld in two different occupant positions. Design of low risk deployment passenger airbag system requires balanced considerations of in-position occupant protection performance and out-of-position performance. A research project has been conducted to investigate those relationships in great details. In this paper, the development of CAE capability to predict low risk deployment passenger airbag behaviors is presented. Using validated CAE mode a series of studies have been conducted to define depowered inflator which can meet the needs of both in-position and out-of-position performances. This forms the key strategy for low risk deployment passenger airbag in design applications.

• Low-Velocity Impact Behaviour of Plain Concrete Beam

  D. Memon (Ghent University), D. Lecompte (Royal Military Academy of Brussels)

  Concrete structures are designed and constructed to serve their anticipated service life, generally with minimal consideration of accidental loads such as impact or explosion. The behaviour of reinforced concrete structures under impact loads has been widely discussed in the last decades, however, there are few studies on the behaviour of plain concrete under impact loading. This paper presents a finite element model of plain concrete beams using nonlinear finite element analysis. The numerical results are compared to experimental data taken from an existing study. The experiments consist of drop-weight tests with varying drop-heights. A parametric study is conducted with respect to the concrete material model and mesh size of elements in order to fine-tune the model and to understand the dynamic response of the beam under low-velocity impact load.

• LS- Dyna on MPP Platforms, Experiences and Practical Recommendations

  Rainer Emrich, Udo Jankowski - Tecosim GmbH

• LS-DYNA "Model Compare" in Visual-Environment

  Shivakumara H. Shetty, Velayudham Ganesa - ESI Group, Milind Parab - Mindware, Sreedhar Kandagatla - ESI Software (India) Pvt Ltd

  A downturn in the industry drives companies to execute projects with fewer resources. The demand for product innovation and productivity improvements has increased exponentially. In order to meet the customers’ demand, ESI’s Visual-Environment provides new features and improvements to achieve productivity, better usability and workflow. One such new feature is “Model Compare”. Using “Model Compare”, a user can compare models to identify the changes in geometry and LS-DYNA entities such as material, section, contact and, constraints. These differences can be copied from one model to another. This feature improves productivity by eliminating manual bookkeeping. In this paper, the key features of Visual-Environment for LS-DYNA and usefulness of these features in FEA simulation are discussed with examples of productivity improvements and process automation.

• LS-DYNA ® Model Development of the Harmonized Hybrid III 05F Crash Test Dummy

  Chirag S. Shah, George Hu, Jianying Li (Humanetics Innovative Solutions, Inc.), Richard Barnes (Ford Motor Company)

  Finite Element (FE) models of Anthropomorphic Test Device (ATD) commonly known as crash test dummies have become increasingly employed in automotive safety with the underlying benefits of cost and product development cycle. The current paper highlights the development of the harmonized Hybrid III 5th percentile (small female) dummy model referred hereafter as the “HH305 V1.0” LS-DYNA FE model. To be compliant with Euro NCAP test requirements, the model has been incorporated with the SAE harmonized jacket and meets both the lower and higher velocity thorax pendulum impact certifications. The development of HH305 V1.0 FE model particularly focused on accuracy of the thorax performance. The thorax performance of the model was evaluated for a variety of loading conditions such as single rib drop tests, thorax pendulum impact tests and the new aggressive seatbelt pretension tests on the thorax assembly. The seatbelt pretension tests were conducted in collaboration with Ford Motor Company and aimed to improve the thorax correlation for relatively smaller chest deflection at faster rate. The HH305 V1.0 model performance is significantly better compared to its predecessor in all the simulated thorax load-cases. The HH305 V1.0 release for the LS-DYNA FE model is commercially available to customers.

• LS-DYNA ® Peridynamics for Brittle Fracture Analysis

  Bo Ren and C. T Wu (Livermore Software Technology Corporation), E. Askari (Boeing Commercial Airplane)

  Peridynamics is a new nonlocal theory that provides the ability to include displacement discontinuities in a continuum body without explicitly modelling the crack surface. In comparison to the classical weakly nonlocal or strictly nonlocal models, the peridynamics equation of motion is free of spatial derivative of displacement. The peridynamics also does not require sophisticated book keeping of degrees of freedom or jump conditions in tracking the moving discontinuities. Those features of peridynamics offer significant advantages over other advanced numerical methods for the brittle fracture analysis particularly in three-dimensional problems. The explicit dynamics version of bond-based peridynamics model has been implemented in LS-DYNA ® using the Discontinuous Galerkin (DG) finite element approach to enforce the boundary conditions, constraints, contacts as well as to handle the non-uniform mesh in the engineering practice. The classic material parameters, such as elastic modulus and fracture energy release rate are employed for the determination of material response and failure in brittle material. The LS-DYNA ® Peridynamics supports 8, 6 and 4-noded solid elements with the ability to handle multiple and branching cracks. Several numerical benchmarks are utilized to demonstrate the effectiveness and accuracy of the LS-DYNA ® peridynamics in brittle fracture analysis.

• LS-DYNA ® Smoothed Particle Galerkin (SPG) Method with Strain Gradient Stabilization and Thermal Effects

  Yong Guo, C.T. Wu, Wei Hu (LSTC)

  The Smoothed Particle Galerkin (SPG) method in gradient form is presented and implemented in LS-DYNA for large inelastic deformation and material failure analyses from low to moderated high speed applications. The new formulation is established following a meshfree Galerkin approach for a solving of partial differential equation in solid mechanics problem and a Strain Gradient Stabilization (SGS) scheme is adopted in linear and nonlinear applications [2-4] for the elimination of zero-energy modes and the enhancement of coercivity. The SPG method in the gradient form recovers the locality of the solution that lacks in the integral form [1]. The discretized system of equation is consistently derived within the penalized meshfree Galerkin variational framework [2] and integrated using a direct nodal integration scheme. The SPG method is also applied to thermal analysis. Several numerical benchmarks and industrial applications are provided in this presentation to demonstrate the effectiveness and accuracy of the new method.

• LS-DYNA ® Structured ALE (S-ALE) Solver

  Hao Chen (LSTC)

  A new Structured ALE solver is recently added into LS-DYNA. It targets to solve ALE problems with structured mesh. It supports all parallel versions of LS-DYNA, i.e., SMP, MPP and MPP Hybrid. The new solver generates structured ALE mesh automatically. The elements do not have to be of equal size. Instead, a user can define element spacing according to needs of the specific engineering problems. Listing all the elements and nodes used for ALE mesh in the input deck becomes unnecessary. Rather, we can simply define the mesh geometry by a number of control point pairs and let the automated mesh generator do the work. For larger ALE problems, the input deck size will be greatly reduced. The execution time on reading in keyword and writing out structured input decks are minimized. Also, changing mesh geometry becomes much simpler. The new S-ALE solver is easy to use, especially for users acquainted to the old generic ALE solver. The solver is automatically invoked with the generated structured mesh. This process is transparent to users. Most ALE keywords remain the same with exception of three new keywords. They are *ALE_STRUCTURED_MESH, *ALE_STRUCUTURED_MESH_CONTROL_POINTS and *ALE_STRUCTURED_MESH_REFINE.

• LS-DYNA 980: Recent Developments, Application Areas and Validation Process of the Incompressible Fluid Solver (ICFD) in LS-DYNA - Part 1

  F. Del Pin, I. Caldichoury (LSTC)

  LS-DYNA version 980 will include CFD solvers for both compressible and incompressible flows. The solvers may run as standalone CFD solvers where only fluid dynamics effects are studied or they could be coupled to the solid mechanics and thermal solvers of LS-DYNA to take full advantage of their capabilities in order to solve fluid-structure interaction (FSI) problems. This paper will focus on the Incompressible CFD solver in LS-DYNA (ICFD) and will be divided in two parts. Part one will present some advanced features of the solver as well some recent developments or improvements. Part two will provide some insight on the validation process that is currently under way in order to better understand the present capabilities and state of advancement of the solvers. Several test cases and results will be presented that will highlight several main features and potential industrial application domains of the solvers. The future steps and the challenges that remain will also be discussed.

• LS-DYNA 980: Recent Developments, Application Areas and Validation Process of the Incompressible Fluid Solver (ICFD) in LS-DYNA - Part 2

  I. Caldichoury, F. Del Pin (LSTC)

  LS-DYNA version 980 will include CFD solvers for both compressible and incompressible flows. The solvers may run as standalone CFD solvers where only fluid dynamics effects are studied or they could be coupled to the solid mechanics and thermal solvers of LS-DYNA to take full advantage of their capabilities in order to solve fluid-structure interaction (FSI) problems. This paper will focus on the Incompressible CFD solver in LS-DYNA (ICFD) and will be divided in two parts. Part one will present some advanced features of the solver as well some recent developments or improvements. Part two will provide some insight on the validation process that is currently under way in order to better understand the present capabilities and state of advancement of the solvers. Several test cases and results will be presented that will highlight several main features and potential industrial application domains of the solvers. The future steps and the challenges that remain will also be discussed.

• LS-DYNA Air Blast Techniques: Comparisons with Experiments for Close-in Charges

  L. Schwer (Schwer Engineering), H. Teng (LSTC), M. Souli (University of Lille)

  Numerical simulations used to predict events are always challenging. Among the challenges is establishing some basis for confidence in the results when no experimental results exist, i.e. a prediction.

• LS-DYNA ALE Nodal Coupling

  H. Chen, J. Wang (LSTC)

  LS-DYNA ALE solver has been used extensively on modeling fluid and gas behaviors. The accompanying FSI solver has been successfully applied on series of engineering problems such as tank sloshing, tire hydroplaning, bottle dropping, HE blasting, etc. The FSI solver, invoked by the *CONSTRAINED_LAGRANGE_IN_SOLID card, is intended to couple between ALE fluid elements and Lagrange structure segments. The LS-DYNA Discrete Elements recently developed has been successfully simulating sand undertaking explosion shockwaves from land mine detonations. In such models, sand is modeled as a group of discrete rigid particles. The pressure wave propagates in the sand through the penalty springs between discrete sand particles. The land mine is modeled by *MAT_HE using ALE multi-material element formulation. However, the existing FSI package can not handle the coupling between the ALE high explosives and sand particles as the FSI algorithm is segment based. This means that the Lagrange structure has to be a set of segments. The new nodal based coupling was developed so that the interaction between ALE fluids and node-based discrete elements could be resolved. The constraint-based coupling algorithm was implemented as the first phase of the development. The keyword is named *ALE_COUPLING_NODAL_CONSTRAINT. It has a similar input format and parameter list as the *CONSTRAINED_LAGRANGE_IN_SOLID card. Preliminary studies of method effectiveness have been done through an in-house land mine blast problem. The results agreed well with empirical data obtained through *LOAD_BLAST_ENHANCED.

• LS-DYNA Analysis of a Full-Scale Helicopter Crash Test

  Martin S. Annett - NASA Langley Research Center

  A full-scale crash test of an MD-500 helicopter was conducted in December 2009 at NASA Langley's Landing and Impact Research facility (LandIR). The MD-500 helicopter was fitted with a composite honeycomb Deployable Energy Absorber (DEA) and tested under vertical and horizontal impact velocities of 26 ft/sec and 40 ft/sec, respectively. The objectives of the test were to evaluate the performance of the DEA concept under realistic crash conditions and to generate test data for validation of a system integrated LS-DYNA® finite element model. In preparation for the full-scale crash test, a series of sub-scale and MD-500 mass simulator tests was conducted to evaluate the impact performances of various components, including a new crush tube and the DEA blocks. Parameters defined within the system integrated finite element model were determined from these tests. The objective of this paper is to summarize the finite element models developed and analyses performed, beginning with pre-test and continuing through post test validation.

• LS-DYNA Analysis of a Sacrificial Wall Designed to Protect Mechanically Stabilized Earth Retaining Walls

  A. Abu-Odeh (Texas Transportation Institute), K.-M. Kim (Samsung C&T Corp.)

  Mechanically Stabilized Earth (MSE) retaining walls are used to provide roadway elevation for bridge approaches, underpass frontage roads and other roadway elevation applications. Vehicular traffic may exist on the high (fill) side of the MSE retaining wall, on the low side, or both sides. For traffic on the high side, a conventional traffic barrier might be placed on or near the top of the wall and mounted on a moment slab or a bridge deck. For traffic on the low side, a conventional traffic barrier might be installed adjacent to the wall or the wall itself may serve as the traffic barrier. Typical MSE wall panels are not designed to resist vehicle impacts. Therefore, structural damage to the wall panels and the earth fill would require complicated and expensive repairs. A simple reinforced concrete crash wall constructed in front of the MSE wall panels can significantly reduce damage to them. It may prove practical to implement such a design in order to reduce costly repair to the MSE wall structure. In this paper, LS-DYNA was used to model and analyze a sacrificial crash wall design to determine its effectiveness of protecting the MSE retaining wall. Based on the LS-DYNA simulations, a 0.2 m. thick crash wall is considered adequately designed to reduce damage to the MSE wall.

• LS-DYNA and JMAG Coupling Simulation for Change of SPM Motor Magnetic Properties Due to Press-Fitting

  Kazuya Sato, Kazuyuki Narita, Hiroyuki Sano - JSOL Corporation

  Press-fitting is one of the methods to keep the laminated structure of the motor core. It is known that the compressive stress due to press-fitting causes an increase of the core-losses. In this paper, the influence of the press- fitting stress on the motor magnetic properties was investigated using LS-DYNA and JMAG coupling simulation. JMAG is a comprehensive software suite for electromechanical equipment design and development. In this investigation, using LS-DYNA for press-fitting analysis, passing the results of the element data to JMAG, finally core-losses analysis was carried out by JMAG. From the results, the change of the magnetic properties due to press- fitting was clearly obtained.

• LS-DYNA application to develop a package for air transportation of fissile materials

  A.V. Abramov, O.V. Voykina, E. Yu. Emelyanova, D. Yu. Karpov, I. A. Kochura, I.V. Minaev - Zababakhin FSUE RFNC-VNIITF

  Object of computer study is a package for FM storage and transportation based on a container AT-400R [1]. Shock and fire resistant container AT-400R was designed at Sandia National Laboratories (USA) and was tested by US and Russian specialists in compliance with the IAEA regulations [2], including cases of flooding, falling of a slab with mass 500 kg from the height of 9 m, container dropping from the height of 1 m onto the pin 150 mm in diameter. In the frames of the ISTC projects # 1216 and 1449, performed computation proved that the IAEA regulations to safe transportation of FM are met. Besides, computation determined limited loading, when 500 kg slab falls from the height of 50 m and freefall of the container from the height of 50 m. When this limited value of loading is outranged, inner containment vessel looses tightness. The objective of this work is to develop a package, based on this container, for FM air transportation, which will provide FM pressure-sealing in conditions that are regulated by up- to-date IAEA requirements – package collision with a target at a velocity 90 m/s.

• LS-DYNA Applications in Shipbuilding

  Hervé Le Sourne, Nicolas Couty, François Besnier - Principa Marine, France, Cyrille Kammerer, Hervé Legavre - DCN Ingénierie, France

  Ship and submarine structures have long been studied thanks to finite element methods. Their large dimension and complexity, the coupling with heavy fluid and the presence of a free surface raise numerical problems on the field of dynamic analysis. This is particularly true for extreme or accidental situations such as collision and grounding, underwater explosion and severe fluid impact. This paper describes first numerical methods and tools developed in LS-DYNA and used in the simulation of ship-submarine collisions, with a focus on the outer collision dynamics, i.e. global motion of the impacted structure. Using a new version of the rigid body dynamic program MCOL included in LS-DYNA, the influence of hydrodynamic effects is highlighted in ship-submarine collisions and in military surface ship collisions. The second part of this paper is dedicated to dynamic response analysis of surface ship or submarines submitted to underwater explosions (UNDEX). Coupled with the Underwater Shock Analysis (USA) code, LS-DYNA is a powerful tool used to simulate the response of ships or submarines to both the shock wave induced by the detonation and the bubble gas effects. Through some examples of 3D numerical models of military vessels, the paper presents the capabilities of the LS-DYNA/USA tool and some difficulties encountered in such an analysis. Impulse loads with high pressure peaks may occur when a ship bottom hits the water with a high velocity. This is often called "slamming”. Sometimes ships suffer from local damage from the impact load or large buckling on the deck. In the last part of this paper, LS-DYNA is used to simulate such water-entries. Interaction between lagrangian bodies and multi-materials eulerian fluids (air and water) is taken into account thanks to a penalty coupling method.

• LS-DYNA Applications in Simulating Impact Tests of Nuclear Fuel Spacer Grids and Drop Tests of Fuel Shipping Packages

  W. Zhao, Z. Karoutas, P. Evans, O. McRae (Westinghouse Electric Company, LLC)

  Presented in the paper are two of our recent LS-DYNA applications in developing simulation models for: (1) impact tests of spacer grid – a key structural component of nuclear fuel, and (2) drop tests of shipping packages for fresh nuclear fuel, as described in the following, in that order. Resistance of nuclear fuel structure to impact loads during postulated seismic and/or loss-of-coolant accident (LOCA) events needs to be demonstrated to show that no excessive fuel structural deformation would occur so that the three criteria are met: (i) fuel rod fragmentation does not occur, (ii) control rod insertion is ensured, and (iii) the core coolable geometry is maintained. The demonstration is accomplished through comparison of prediction through full core simulation with the strengths of the various structural components of the fuel. The impact tests of the spacer grids provide one such strength. As the impact test of the spacer grids requires significant lead time and effort, capability to simulate the spacer grid behavior under testing conditions is of great interest. More importantly, it provides a powerful tool for design. To meet shipping package safety requirements for transporting fresh nuclear fuel assemblies, structural performance of the shipping package under hypothetical accident conditions must be evaluated and demonstrated to have adequate protection to the fuel assembly it transports. To efficiently evaluate design changes in the shipping package, a simplified finite element model for the shipping package and fuel assembly has been developed using LS- DYNA. The development and validation of the finite element model, along with a few design analysis examples to illustrate its usefulness are described.

• LS-DYNA Automatic Re-Decomposition

  E. Yreux, C. Tsay, J. Wang (LSTC)

  The default decomposition method for LS-DYNA/MPP is RCB which dividing the model based on the initial geometry. If the geometry does not severely distorted during the simulation, this decomposition gives reasonable scaling upto few hundreds cores. LS-DYNA also provides additional “pfile” options which relies on user’s knowledge of deformation to achieve better MPP efficiency. Unfortunately, there are many problems cannot be easily treated by those options, i.e. bird strike, water wading, FBO, etc. The simulations involve parts with relative motion which are difficult to decompose only once and those jobs are usually suffer from the scaling. Furthermore more cores are used in the simulation, a load unbalancing effects will be amplified and results in poor scalability. To Achieve better computational load balancing, a new automatic re-decomposition algorithm has been implemented recently. The new method can readjust the load balancing during simulation based on the current geometry. In this study, we will give some typical examples to show how to regain the load balancing and improve the parallel efficiency.

• LS-DYNA Beam Elements: Default and User Defined Cross Section Integration

  Len Schwer - Schwer Engineering and Consulting Services, USA

  LS-DYNA provides several beam element formulations, see the keyword description for *Section_Beam in the User’s Manual. Several of these beam element formulations support user supplied integration of the cross section, via the *Integration_Beam keyword. While most LS-DYNA users are familiar with the similar through-the-thickness integration algorithm for shell elements, which is made trivial by the rectangular cross section geometry assumed for shell elements, the numerical integration of even simple beam element cross sections requires more effort, and as will be demonstrated, more planning. In this article, a detailed explanation of the beam element cross section integration algorithm is presented. Simple suggestions for calculating, and checking, user provided integration rules are illustrated through several examples. The examples also provide suggestions for improving the LS-DYNA Standard Cross Section Types, available via the ICST parameter of the *Integration_Beam keyword.

• LS-DYNA Best-Practices: Networking, MPI and Parallel File System Effect on LS-DYNA Performance

  Gilad Shainer - HPC Advisory Council, Tong Liu - Mellanox Technologies, Jeff Layton, Onur Celebioglu - Dell

  From concept to engineering, and from design to test and manufacturing, the automotive industry relies on powerful virtual development solutions. CFD and crash simulations are performed in an effort to secure quality and accelerate the development process. The recent trends in cluster environments, such as multi-core CPUs, GPUs, cluster file systems and new interconnect speeds and offloading capabilities are changing the dynamics of clustered- based simulations. Software applications are being reshaped for higher parallelism and multi-threads, and hardware configuration for solving the new emerging bottlenecks, in order to maintain high scalability and efficiency. In this paper we cover best practices for achieving maximum productivity through MPI optimizations, efficient networking utilization and usage of parallel file systems.

• LS-DYNA Communication Performance Studies

  Ananthanarayanan Sugavanam, Guangye Li - IBM

  In recent years, MPP-DYNA, the message passing parallel version of LS-DYNA, has become more and more popular in car crash and metal stamping simulations due to its good scalability which may reduce the turn-around time significantly when more processors are used. However, so far, most users only use 16 or less processors for LS-DYNA simulation because of the limitation of the scalability on a larger number of processors. This paper analyzes the communication patterns, message sizes and costs of simulation of two models. It is concluded that the unbalanced work load among processes is the bottleneck for scalability. Our study shows that some special decomposition techniques including sliding interface decomposition and scaling on certain directions may produce more balanced work load and, therefore, improve scalability. It is our hope that this study provides some insight for the algorithm improvement which may lead to better MPP-DYNA scalability on a larger number of processors.

• LS-DYNA Data Management using Visual-Environment

  S.H. Shetty, V. Ganesan, S.C. Sivalingam, E. De Pommery, J.L. Duval - ESI Group

  Realistic Simulation is considered to be the most important part of Simulation Based Design (SBD) in the product development cycle. Realistic simulations can not be achieved just by using currently available CAE pre and post processing functionalities alone. Many of the complex requirements of CAE modeling need to be addressed by having a synchronized CAD and CAE environment. CAE analysts need a tool, which will allow them to control variables, manage data, adapt the changes, and transport across different disciplines of analysis such as Crash, Safety, NVH and Durability. ESI’s Open VTOS™ application called “Visual-Environment (VE)” provides such capabilities as a complete solution to SBD. VE is an integrated suite of pre-post, CAE data management tools synchronizing CAD and CAE. It also provides several contexts based on individual FE solvers. Visual-Crash DYNA (VCD) is for LS-DYNA model setup, Visual-Composer (VCO) is for model assembling and data management by linking CAD (Geometry) and FE (Physics). VCO and VCD allow managing LS-DYNA model data linking to corresponding CAD assemblies. It helps to adapt fast design changes, communicate the engineering changes back to design, and to track the models and solutions of multiple iterations. Visual-Safe is an advanced pre-processor for safety features, Visual-Mesh a general purpose meshing tool, Visual-Viewer (VVI)-a general purpose plotting and simulation application, Visual-Life Nastran (VLN) a general purpose pre processor for NASTRAN, Visual-Process Executive-an application for process customization and automation are the other contexts to name a few.

• LS-DYNA Durability Load Cases: An Automated Template Driven Process Using the ANSA Task Manager

  Yianni Kolokythas - BETA CAE Systems SA, Dietmar Fels, Matthias Weinert - Ford-Werke GmbH

  Process organization and standardization are essential in a CAE turnaround cycle. In an era, where the vehicle development time is getting reduced and the number of load case analysis is getting increased, the need for automatic standard processes is increasing. Ford-Werke GmbH and BETA CAE Systems SA are cooperating to develop streamlined, automatic processes, using the ANSA Task Manager. The goal, of these template driven processes, are to create realistic, repeatable and robust durability simulation models. The ANSA Task Manager supervises the generation of the simulation models, while ANSA Data Management, in the background, facilitates the components management, ensuring that the engineering teams will always work with the most up-to-date data. The simulation model set-up becomes a repeatable and user-independent procedure, safeguarding the model quality and fidelity.

• LS-DYNA Features for Hot Forming

  Arthur Shapiro - LSTC

  LS-971 has several features to model the hot forming process. A thick thermal shell formulation for the blank allows modeling a temperature gradient through the thickness. The keyword, *MAT_ADD_THERMAL_EXPANSION, allows calculating thermal strains for all the mechanical material models. A user-defined flag is available to turn off thermal boundary conditions when part surfaces come in contact. A thermal oneway contact algorithm is available to more accurately calculate contact between a die zoned with a CAD type surface mesh when in contact with a uniform meshed blank. Thermal-mechanical contact user defined parameters allow modeling the coefficients of friction as a function of temperature and thermal contact resistance as a function of interface pressure. A new feature models bulk fluid flow through the die cooling passages.

• LS-DYNA Features for Hot Stamping

  Arthur B. Shapiro - LSTC

  LS-971 has several new features to model the hot stamping process. A thick thermal shell formulation allows modeling a temperature gradient through the thickness of the shell. The new keyword, *MAT_ADD_THERMAL_EXPANSION, allows calculating thermal strains for all the mechanical material models. A new feature has been added to thermal contact which turns off thermal boundary conditions when surfaces come in contact. A new thermal one-way contact algorithm has been added which more accurately models heat transfer between a blank and die. New features have been added to thermal-mechanical contact which allows modeling the coefficients of friction as a function of temperature and thermal contact resistance as a function of interface pressure.

• LS-DYNA Implemented Multi-Layer Fabric Material Model Development for Engine Fragment Mitigation

  S. D. Rajan, B. Mobasher, A. Vaidya - Arizona State University

  The development of a robust and reliable material model for dry fabrics is the main subject of this paper. Dry fabrics are used in a number of applications such as propulsion engines fan-containment systems, and soft body armor. A mechanistic-based material behavior model capturing the behavior of fabrics when subjected to impacts from high-velocity projectiles would make a powerful predictive tool. In this paper, the constitutive model for Kevlar® 49 is developed. Experimental static and high strain rate tensile tests have been conducted at Arizona State University (ASU) to obtain the material properties of Kevlar fabric. Results from laboratory tests such as Tension Tests including high-strain rate tests, Picture Frame Shear Tests, and Friction Tests yield most of the material properties needed to define a constitutive model. The material model is incorporated in the LS-DYNA commercial program as a user-defined subroutine. The validation of the model is carried out by numerically simulating actual ballistic tests conducted at NASA-GRC.

• LS-DYNA Implicit for Dent Performance Evaluation

  Gagan Tandon, Venugopal Bachu - Altair Engineering Inc.

  Present day engineering design involves complex CAE analyses using both linear and non-linear methods. Mos companies use multiple software tools for different types of analyses. Several reasons, including cost are driving companies to investigate lesser number of FEA tools so that they can use a single solver for most of their structural analyses. LS-DYNA has been traditionally used for explicit analysis like crash and metal forming. Recent enhancements in the versions of LS-DYNA enable us to evaluate it for implicit analysis. The success of an automotive design is determined by its ability to meet the expectations of the customer with respect to cost, performance and styling. Dent performance is an important factor in designing automotive outer panels due to increased customer sensitivity to surface finish and durability. Dent performance is defined as the deflection under certain external loads at the panel outer surface. The external loads can be from many sources like shopping carts or from an adjacent vehicle door in a parking lot. Dent performance prediction assumes a quasi-static equilibrium solution eliminating the effects of inertia, thereby making it an implicit analysis. Dent prediction analyses are traditionally performed using specialized implicit solvers. In this study, LS-DYNA implicit was used to predict dent performance on several outer panels (doors & hoods). The results were then compared to the corresponding experimental results and to the results from a competing solver. This paper also describes the setup using Altair HyperMesh, various analysis parameters and element formulations used for dent analysis.

• LS-DYNA Meshfree Interactive Adaptivity and Its Application

  Wei Hu, C. T. Wu - Livermore Software Technology Corporation, Kei Saito - Engineering Technology Division, JSOL Corporation

  The meshfree adaptive method has been developed and widely used as an important tool to deal with large topology change with severe local deformation in the application of 3D metal forming analysis. However, due to the complexity of material deformation, it is impractical to predefine the adaptivity before the actual analysis is performed. The interactive adaptivity will be an alternative to dynamically detect distortion and maintain the quality of meshfree discretization. In this work, we are going to present a new development on meshfree interactive adaptivity. Several control indicators are introduced to measure the local distortion in discretization as material deforms. When one or more indicators are beyond certain tolerance, which indicates the occurrence of severe shear deformation, large volumetric change, or unbalanced nodal distribution, meshfree interactive adaptivity is triggered. The user defined tolerance is carefully adjusted according to the history of material deformation to avoid the over-activation of interactive adaptivity. Several numerical examples will be presented to demonstrate the advantages of interactive adaptivity and compared to the traditional approach.

• LS-DYNA Model Development of the Harmonized Hybrid III 05F Crash Test Dummy

  C. Shah (Humanetics Innovative Solutions), C. Kleeßen, R. Kant, P. Lemmen (Humanetics Europe)

  Starting per January 2015 Euro NCAP requires use of the HIII-5th percentile small female for its full width frontal barrier test procedures. The dummy should be according to the latest agreed FTSS / Denton brand harmonization and thereby eliminates brand variability effects. The dummy configuration includes a neoprene neck shield, the SAE harmonized jacket (SAE J2921) and the Denton lower leg cavities. In addition, the thorax pendulum certification should be done for both 3.

• LS-DYNA Model Development of the THOR-M

  I. Maatouki, P. Lemmen (Humanetics Europe), Z. Zhou (Humanetics Innovative Solutions)

  Developments on the THOR dummy over the past years resulted in the THOR-M version which is foreseen for introduction into regulatory and Consumer tests in the 2020 timeframe. NHTSA considers to use the THOR-M dummy in an angled impact test while Euro NCAP includes plans for the development of a frontal barrier test with THOR-M in their roadmap for 2020. To support the development of restraint systems for both test configurations Humanetics is developing a Finite Element model of the THOR-M dummy.

• LS-DYNA on Advanced SGI Architectures

  Olivier Schreiber, Scott Shaw, Brian Thatch - SGI Applications Engineering, Bill Tang - SGI Systems Engineering

  LS-DYNA’s implicit solver integration with explicit software allows large time steps transient dynamics as well as linear statics and normal modes analysis. Until recently,this capability could only be run on large Shared Memory Parallel (SMP) systems,where the application had access to large memory address space of the model. Distributed Memory Parallel (DMP) implementation of LS-DYNA’s implicit solver now allows the factorization of smaller mass and stiffness matrices of the decomposed problem domain by corresponding tasks in less memory. Performance enhancement through SMP processing is moreover also available in the recently introduced ‘hybrid’ mode. This paper demonstrates how advanced SGI computer systems, ranging from SMP servers addressing large memory space through multi-node clusters can be used to architect and accelerate solutions to meet complex analysis requirements.

• LS-DYNA on Linux-Clusters at EDAG Use Case

  John U.S. Hanlon - EDAG Engineering & Design AG, Bernward Platz - Teraport GmbH

  At EDAG, the increasing demand for crash simulations with LS-DYNA required the expansion of the existing compute resources in the beginning of 2002. As at this point there was a stable and performant MPP-version of LS-DYNA available, EDAG decided - despite of the new technology - to purchase a Linux-cluster consisting of 8 nodes and 16 processors. Meanwhile EDAG has deployed over 14 clusters at three different locations. Whereas at the beginning, purchase costs and performance played a major role, due to the increasing complexity further demands became important which were realised by the EDAG partner, Teraport: fast, convenient and reproducible installation and administration of the cluster systems parallel usage of several DYNA versions with various MPI-libraries easy extensibility convenient usage of cluster resources via web technologies high-available access to the cluster resources handling of high data transfer integration of further FEM-applications The paper describes a use case which reports the concepts of the realisation of these requirements as well as the problems such as hardware quality during the installation and setup of the cluster environment. At the end, a perspective concerning further possibilities of development such as web-based workflow optimization and result management will be shown.

• LS-DYNA Performance and Scalability in the Multi-Core Environment

  Gilad Shainer - Mellanox Technologies

  Efficient data transfer between clustered compute nodes is critical for balanced system performance. In a balanced system, the overall performance is equal to or greater than the sum of its components, while in a non-balanced system, the performance is less than the sum. The challenge of achieving balanced performance becomes more evident in multi-core environments. A multi-core environment introduces high demands on the cluster interconnect and the interconnect must handle multiple I/O streams simultaneously. In this paper we explore the benefits of InfiniBand high-speed connectivity solution for multi-core clusters, and show the scalability and efficiency of LS-DYNA on InfiniBand connected multi-core cluster platforms.

• LS-DYNA Performance Enhancement of Fan Blade Off Simulation on Cray XC40

  Ting-Ting Zhu (Cray Inc.), Jason Wang, Brian Wainscott (LSTC)

  This work uses LS-DYNA to enhance the performance of engine FEA simulation of fan blade off containment test on Cray XC40 supercomputers. Blade off containment test is a specific form of air safety test required by the Federal Aviation Administration and other safety agencies, which involves the intentional release of a fan blade when engine is running at full power. The released blade must be contained within the fan cases during the impact and imbalanced rotation. The simulation of fan blade off containment test is technically challenging and computationally intensive. To enhance the performance of fan blade off containment simulation, some improvements are made in surface to surface erosion contact in LS-DYNA version R8.0.0. In this study, the performance of fan blade off simulation using LS-DYNA version R8.0.0 is compared with that using LS-DYNA version R7.1.2 on a Cray XC40 supercomputer. In addition, the MPI communication patterns and load balance among the MPI processes in the fan blade off containment simulation is also analyzed. Finally, a very large model of fan blade off simulation with more than 80 million elements, which used to be a daunting task that took a modern MPP computer more than a month to complete, is carried out using LS-DYNA version R8.0.0 on the Cray XC40 computer.

• LS-DYNA Performance Improvements with Multi-Rail MPI on SGI Altix ICE Clusters

  Olivier Schreiber, Michael Raymond, Srinivas Kodiyalam - SGI

  Multi-Rail networks can improve MPI communication performance by distributing the communication traffic to multiple independent networks (rails). Messages are divided into several chunks and sent out simultaneously using multiple rails. With the dual plane network topology of SGI Altix ICE clusters, MPI communication can hence utilize both the InfiniBand rails, including, ib0 and ib1 fabrics. The performance gains achievable with LS-DYNA for complex crashworthiness simulations through the use of MPT dual-rail over MPT singe-rail on an Altix ICE system are indeed significant.

• LS-DYNA performance on new computing choices from IBM

  Guangye Li, Jeff Zais, Greg Clifford - IBM

• LS-DYNA PERFORMANCE ON ULTRASPARCTM -III SERVERS AND WORKSTATIONS

  Youn-Seo Roh, Henry H. Fong - Sun Microsystems

  Sun Microsystems recently announced a new line of high-performance Sun FireTM Midframe servers and Sun BladeTM 1000 workstations based on 750-MHz UltraSPARC-III microprocessors. These new computers offer exceptional performance for numerically intensive MCAE applications at reasonable prices. This paper presents single- and multi-processor performance and scalability results of LS-DYNA running on these systems. Results of both OpenMP and MPI binaries are compared to those of existing server platforms. Scalability and performance results are presented for the OpenMP binary that has been built with Sun's native OpenMP compiler extension. Comparisons with a previous version using libraries from KAI show significant improvements both in the absolute execution time and the scalability. The MPI executable tuned for the new Sun Fire server resulted in a 40-60% improvement in execution time over the entire range of processor counts.

• LS-DYNA Productivity and Power-aware Simulations in Cluster Environments

  Gilad Shainer, Tong Liu - Mellanox Technologies, Jacob Liberman, Jeff Layton, Onur Celebioglu - Dell, Inc., Scot A. Schultz, Joshua Mora, David Cownie - Advanced Micro Devices (AMD), Ron Van Holst - Platform Computing

  From concept to engineering and from design to test and manufacturing; engineering relies on powerful virtual development solutions. Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) are used in an effort to secure quality and speed up the development process. Cluster solutions maximize the total value of ownership for FEA and CFD environments and extend innovation in virtual product development. Multi-core cluster environments impose high demands for cluster connectivity throughput, low-latency, low CPU overhead, network flexibility and high-efficiency in order to maintain a balanced system and to achieve high application performance and scaling. Low-performance interconnect solutions, or lack of interconnect hardware capabilities will result in degraded system and application performance. Livermore Software Technology Corporation (LSTC) LS-DYNA software was investigated. In all InfiniBand-based cases, LS-DYNA demonstrated high parallelism and scalability, which enabled it to take full advantage of multi-core HPC clusters. Moreover, according to the results, a lower-speed interconnect, such as GigE or 10 Gigabit Ethernet are ineffective on mid to large cluster size, and can cause a reduction in performance beyond 16 or 20 server nodes (i.e. the application run time actually gets slower) We have profiled the communications over the network of LS-DYNA software to determine LS-DYNA sensitivity points, which is essential in order to estimate the influence of the various cluster components, both hardware and software. We evidenced the large number of network latency sensitive small messages through MPI_AllReduce and MPI_Bcast operations that dominate the performance of the application on mid to large cluster size. The results indicated also that large data messages are used and the amount of the data sent via the large message sizes increased with cluster size. From those results we have concluded that the combination of a very high-bandwidth and extremely low-latency interconnect, with low CPU overhead, is required to increase the productivity at mid to large node count. We have also investigated the increase of productivity from single job to multiple jobs in parallel across the cluster. The increase of productivity is based on two facts. First, good scalability of AMD architecture that allows to run multiple jobs on a given compute node without saturating the memory controller. Second, the low latency and high bandwidth available on the InfiniBand interconnect that allowed us to offload the CPU to CPU data traffic from MPI communications via the interconnect instead of in compute node. The net result of that practice is an increase of the productivity by a factor of 200% with respect to the single job run. Finally, the increase of productivity on single job runs with high speed interconnects has been analyzed from the point of view of power consumption leading to a 60% reduction or energy savings when using InfiniBand with respect to Ethernet.

• LS-DYNA Productivity and Power-aware Simulations in Cluster Environments

  Gilad Shainer, Tong Liu - Mellanox Technologies, Jacob Liberman, Jeff Layton, Onur Celebioglu - Dell, Inc., Scot A. Schultz, Joshua Mora, David Cownie - Advanced Micro Devices (AMD), Ron Van Holst - Platform Computing

  From concept to engineering and from design to test and manufacturing; engineering relies on powerful virtual development solutions. Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) are used in an effort to secure quality and speed up the development process. Cluster solutions maximize the total value of ownership for FEA and CFD environments and extend innovation in virtual product development. Multi-core cluster environments impose high demands for cluster connectivity throughput, low-latency, low CPU overhead, network flexibility and high-efficiency in order to maintain a balanced system and to achieve high application performance and scaling. Low-performance interconnect solutions, or lack of interconnect hardware capabilities will result in degraded system and application performance. Livermore Software Technology Corporation (LSTC) LS-DYNA software was investigated. In all InfiniBand-based cases, LS-DYNA demonstrated high parallelism and scalability, which enabled it to take full advantage of multi-core HPC clusters. Moreover, according to the results, a lower-speed interconnect, such as GigE or 10 Gigabit Ethernet are ineffective on mid to large cluster size, and can cause a reduction in performance beyond 16 or 20 server nodes (i.e. the application run time actually gets slower) We have profiled the communications over the network of LS-DYNA software to determine LS-DYNA sensitivity points, which is essential in order to estimate the influence of the various cluster components, both hardware and software. We evidenced the large number of network latency sensitive small messages through MPI_AllReduce and MPI_Bcast operations that dominate the performance of the application on mid to large cluster size. The results indicated also that large data messages are used and the amount of the data sent via the large message sizes increased with cluster size. From those results we have concluded that the combination of a very high-bandwidth and extremely low-latency interconnect, with low CPU overhead, is required to increase the productivity at mid to large node count. We have also investigated the increase of productivity from single job to multiple jobs in parallel across the cluster. The increase of productivity is based on two facts. First, good scalability of AMD architecture that allows to run multiple jobs on a given compute node without saturating the memory controller. Second, the low latency and high bandwidth available on the InfiniBand interconnect that allowed us to offload the CPU to CPU data traffic from MPI communications via the interconnect instead of in compute node. The net result of that practice is an increase of the productivity by a factor of 200% with respect to the single job run. Finally, the increase of productivity on single job runs with high speed interconnects has been analyzed from the point of view of power consumption leading to a 60% reduction or energy savings when using InfiniBand with respect to Ethernet.

• LS-DYNA Simulation of in vivo Surgical Robot Mobility

  Mark Rentschler, John D. Reid - University of Nebraska

  In vivo surgical robot wheels were studied to develop a better wheel design using finite element analysis. A liver material model, derived from component testing, was implemented as a viscoelastic material. LS-DYNA simulation of this testing confirmed the accuracy of the liver material model. This material model was then used as the tissue model to study wheel performance. A helical wheel moving on the liver model was used to replicate laboratory experiments. Drawbar forces required to move the wheel across the liver for various slip ratios produced in simulation showed good agreement with the physical tests. The wheel design was then adjusted in the simulation to study how changes in the wheel diameter and the pitch of the helical tread affected the drawbar force. Results showed that an increased diameter and decreased pitch angle increased drawbar force. These results will be used in future surgical robot wheel designs.

• LS-DYNA Simulations of the Impacts of a 38-Ton Heavy Goods Vehicle into a Road Cable Barrier

  K. Wilde, D. Bruski, S. Burzyński, J. Chróścielewski, Ł. Pachocki, W. Witkowski (Gdańsk University of Technology)

  Nowadays, more and more attention is being paid to safety on roads and motorways. It is due to the continuous development of road and motorway network and a significant increase of the number of vehicles on roads. To meet the expectations of improving road safety in Poland, the Road Innovations Development (RID) research programme was implemented in 2016. The aim of the RID 3A - Road Safety Equipment (RoSE) project is a comprehensive analysis of various road restraint systems and various types of road safety equipment installed on roads and bridges. The RID 3B - Effect of time and operating conditions of the durability and functionality of the elements of road safety (LifeRoSE) complementary project is aimed at developing innovative and comprehensive road management methodology for road safety equipment and traffic management measures. Part of the aforementioned projects is a thorough study of safety barriers based, among others, on full-scale crash tests and a number of numerical simulations using LS-DYNA. The aim of the paper is to assess the crashworthiness of a road cable barrier during an impact of a Heavy Goods Vehicle (HGV) weighing 38 tons. A numerical model of the safety device was developed and validated with a full-scale crash test. Based on this computational model, a series of virtual crash tests were carried out in which the HGV collides with the barrier under various impact conditions. Some of the cases will be compared with real accident outcome that took place on highway in Poland.

• LS-DYNA USED TO ANALYZE THE MANUFACTURING OF THIN WALLED CANS

  Joachim Danckert - Aalborg University

  The ironing process and the backward can extrusion process are widely used for the manufacturing of thin walled cans. In the ironing process the die is commonly made with a cylindrical die land and in backward can extrusion the punch is commonly made with a cylindrical punch land. LS-Dyna has been used in the analysis of the influence, which the die land and the punch land have. The results suggest that a small misalignment of the die land, respectively the punch land may cause the process to become unstable resulting in uneven can height and uneven can wall thickness. Simulations also suggest that it is possible, by making minor changes to the geometry of the die land respectively the punch land, to make the process significantly more robust with regard to the influence from a small misalignment of the land. The results obtained from the LS-Dyna simulations are in good agreement with experimentally obtained results.

• LS-DYNA used to analyze the drawing of precision tubes

  Prof. Dr.techn. Joachim Danckert, Dr. Benny Endelt - Aalborg University, Denmark

  Long precision tubes are commonly made using the floating plug tube drawing process. The process has been analyzed using various methods e.g. upper bound method and FEM [1-10]. The die land and the plug land are usually cylindrical and form a cylindrical bearing channel between the die land and the plug land. The influence from the length of the bearing channel on the drawing force has only been dealt with in very few papers. In [2] it is recommended to use the shortest possible bearing channel in order to reduce the drawing force. A short bearing channel is also recommended in [6] both in order to reduce the drawing force, but also in order to increase the stability of the drawing process. The authors have not found any papers dealing with which influence the shape of the bearing channel has. The paper describes an analysis of tube drawing with a floating plug carried out using LS-DYNA®. The analysis shows that the drawing force, with conventional tooling, is heavily influenced both by the length and the shape of the bearing channel. The analysis has given inspiration to a new plug design, where the cylindrical plug land is replaced with a circular profiled plug land. Simulations of tube drawing with the new plug design show that the drawing force can be decreased and that the drawing force is nearly independent of the length of the die land and of small variations in the die land angle. With a conventional plug it is necessary at start up to make a dent in the tube behind the plug in order to force the plug into the right position in relation to the die. Without a dent the plug will be pushed ahead of the die and no reduction of the tube wall thickness will take place between the plug land and the die land. The dent is commonly made manually with a hammer and making the dent is difficult. If the dent is not made big enough the plug may pass the dent without being brought in the right position in relation to the die and if the dent is made too large this may lead to tube fracture. To ease the threading process at start up it is suggested to make the plug with a conical front end. By doing so the plug becomes self-catching; that is the frictional forces between the conical front end and the inside tube wall will set the plug in the right position in relation to the die during start up. Simulations show that the “self-catching plug” principle works.

• LS-DYNA used to analyze the drawing of precision tubes

  Prof. Dr.techn. Joachim Danckert, Dr. Benny Endelt - Aalborg University, Denmark

  Long precision tubes are commonly made using the floating plug tube drawing process. The process has been analyzed using various methods e.g. upper bound method and FEM [1-10]. The die land and the plug land are usually cylindrical and form a cylindrical bearing channel between the die land and the plug land. The influence from the length of the bearing channel on the drawing force has only been dealt with in very few papers. In [2] it is recommended to use the shortest possible bearing channel in order to reduce the drawing force. A short bearing channel is also recommended in [6] both in order to reduce the drawing force, but also in order to increase the stability of the drawing process. The authors have not found any papers dealing with which influence the shape of the bearing channel has. The paper describes an analysis of tube drawing with a floating plug carried out using LS-DYNA®. The analysis shows that the drawing force, with conventional tooling, is heavily influenced both by the length and the shape of the bearing channel. The analysis has given inspiration to a new plug design, where the cylindrical plug land is replaced with a circular profiled plug land. Simulations of tube drawing with the new plug design show that the drawing force can be decreased and that the drawing force is nearly independent of the length of the die land and of small variations in the die land angle. With a conventional plug it is necessary at start up to make a dent in the tube behind the plug in order to force the plug into the right position in relation to the die. Without a dent the plug will be pushed ahead of the die and no reduction of the tube wall thickness will take place between the plug land and the die land. The dent is commonly made manually with a hammer and making the dent is difficult. If the dent is not made big enough the plug may pass the dent without being brought in the right position in relation to the die and if the dent is made too large this may lead to tube fracture. To ease the threading process at start up it is suggested to make the plug with a conical front end. By doing so the plug becomes self-catching; that is the frictional forces between the conical front end and the inside tube wall will set the plug in the right position in relation to the die during start up. Simulations show that the “self-catching plug” principle works.

• LS-DYNA User-Defined Internal Ballistic Modeling

  Sirri Oğuz

  One of the challenges in modeling deflagration of solid propellants with LS-DYNA is its limited capability, which is mostly applicable to airbag systems that use gaseous nitrogen generated by burning sodium azide. To overcome this limitation and enable the modeling of custom propellant grains with specific geometries, perforations, surface inhibitors, impetus, burn rates, and co-volumes, a user-defined burn model must be defined. In this study, a custom internal ballistic analysis code is integrated into LS-DYNA to simulate kinematic systems driven by pyro-mechanical devices such as pyro pushers, cutters, thrusters, separations bolts, ejection seat catapults, etc. Step-by-step guidance is provided on implementing a user-defined loading subroutine and the requirements for compiling a custom LS-DYNA executable along with a simple pyro thruster example.

• LS-DYNA® ALE Modeling of Blast in an Urban Environment

  Sergey Medyanik, Michigan Engineering Services, LLC;, Syed Mohammad, Department of Homeland Security;, Nickolas Vlahopoulos, University of Michigan

  In LS-DYNA finite element analysis software, Arbitrary Lagrangian Eulerian (ALE) approach can be applied to modeling dynamic loading due to explosives. The main advantage of this method is its good accuracy as it explicitly models the explosive and the pressure wave propagation through the media. However, this approach typically requires using very fine meshes in order to accurately model problems characterized by high peak pressures as mesh refinement in the close vicinity of the explosive can be crucial for obtaining accurate results. In this work, the effects of an air blast in an urban environment are examined using a simple geometric model of a street intersection configuration typical of a city business district. Accuracy and mesh sensitivity of the results in terms of the peak pressures at certain gauge points are investigated. The modeling approach is verified by comparing the numerical results from the finite element models to experimental data found in the literature.

• LS-DYNA® ALE/FSI Recent Developments

  Hao Chen, Jason Wang, Ian Do (LSTC)

  LS-DYNA ALE(Arbitrary Lagrange-Eulerian Method), equipped with its own fluid-structure interaction, aims to solve a series of transient engineering problems characterized by large momentum and energy transfer between Lagrange structures and ALE fluids. LS-DYNA ALE multi-material formulation solves multiple species of fluids in one ALE mesh. The fluid interfaces are tracked internally by our interface reconstruction algorithms at each of the advection cycle. Then our fluid-structure interaction algorithm is used to study the interactions between structures and those individual fluids. The FSI solver, invoked by the *CONSTRAINED_LAGRANGE_IN_SOLID card, is to couple between ALE fluid elements and Lagrange structure segments. The multi-material capability, together with its embedded coupling to structures, have been utilized by users from various engineering application areas such as tank sloshing, tire hydroplaning, bottle dropping, high explosive blasting, etc. Several recent developments and their engineering applications in LS-DYNA ALE/FSI package are presented here.

• LS-DYNA® Belted Occupant Model

  Stephen Kang, Cong Chen, Manjeera Paladugu, Murugan Sundaram Ramasamy, Lalitha Gade, Ford Motor Company;, Sarba Guha, Livermore Software Technology Corporation;, Fuchun Zhu, Humanetics Innovative Solutions

  The seat belt is one of the most critical components in automotive crash safety. The three-point belt system has been around for fifty-eight years, belt pretensioners for thirty years and retractor torsion bar load limiters for eighteen years. Though the belt system has been around for so long, CAE correlation to physical test is still limited and far from having high confidence predictive capability. There are numerous CAE parameters and all their values have to be carefully determined, to represent the physics of crash testing and for the CAE models to have good predictive value. How well the belt system is modeled in CAE can directly affect occupant correlation and our predictions.

• LS-DYNA® Big Data Processing, Mining and Visualization using d3VIEW

  Suri Bala (LSTC)

  LS-DYNA Data Processing, Storage and Visualization consume a lot of time and effort for every Engineer and Scientist who uses simulations to aid product development. This paper reviews commonly used workflows in simulation based product design to identify areas where d3VIEW can significantly reduce time and effort in data intensive tasks. In conclusion, this paper will demonstrate by example how d3VIEW provides advanced capabilities in data extraction, organization and visualization of LS-DYNA simulations to expedite the process of going from Data to Decision while providing extensive capabilities in mining historical LS-DYNA simulations.

• LS-DYNA® HYBRID Studies using the LS-DYNA® Aerospace Working Group Generic Fan Rig Model

  Gilbert Queitzsch (Federal Aviation Administration), Cing-Dao Kan, Kivanc Sengoz (George Mason University), Thomas J. Vasko (Central Connecticut State University)

  In addition to the well-known parallel versions of LS-DYNA, the symmetric multiprocessing (SMP) version and massively parallel processor (MPP) version, LSTC offers an LS-DYNA HYBRID version that combines these two parallel programming models into a single code. The development of LS-DYNA HYBRID, which started in 2011, is focused on obtaining high code performance on large cluster environments. The intent of the current study is to investigate the LS-DYNA HYBRID performance, scalability, and output consistency using a modified LS-DYNA Aerospace Working Group Generic Fan Rig Model. The original model is an outcome of a Federal Aviation Administration (FAA) funded university project and it is used as a test case for the LS-DYNA Aerospace Working Group Test Case Suite.

• LS-DYNA® Impact Model Build-up: Process Automation With ANSA Data Management and Task Manager

  I. Makropoulou, Y. Kolokythas, L. Rorris - BETA CAE Systems S.A., Greece

  In the presently CAE-driven vehicle design process a great number of discipline models must be built and analyzed for the validation of a new vehicle model design. The increasing number of vehicle model variants further increases the number of the load-cases that must be studied. This process introduces a great amount of disparate data that need to be handled by the CAE teams. However, due to the multiple sources and the diversity of the CAE data, the current level of organization and data management deployed does not account for them. Setting as a target the reduction of the CAE turnaround cycle and cost, the pre-processing tools are required to streamline all “input” data and at the same time the simulation model build-up process itself, .this paper will present the means provided by BETA CAE Systems S.A. towards the development of realistic, repeatable and robust crash simulation models for LS-DYNA. ANSA Task Manager, using template processes, supervises the generation of the simulation models, while ANSA Data Management, in the background, facilitates the components management, ensuring that the engineering teams will always work with the most up-to-date data. The simulation model set-up becomes a repeatable and user-independent procedure, safeguarding the model quality and fidelity

• LS-DYNA® Impact Simulation of Composite Sandwich Structures with Balsa Wood Core

  L. J. Deka, U. K. Vaidya - The University of Alabama at Birmingham

  The impact damage response of balsa core sandwich composite plates with S2-glass/ epoxy reinforced facesheets is evaluated by impacting them with a spherical steel projectile at single impact locations. The impact damage can significantly reduce the structural integrity and load bearing capacity of a composite structure. Under high velocity impact loading, laminated composites experience significant damage causing fiber breakage, matrix cracking and delamination. Energy absorption and delaminations from high velocity impacts with spherical projectile of .30 caliber is discussed. Finite element modeling was used to gain insight into failure modes, energy absorption, and damage prediction. During high velocity impact, composite laminates undergo progressive damage and hence, Material Model 162, a progressive failure model based on Hashin’s criteria, has been assigned to predict failure of the laminates. The laminates, the projectiles and the balsa wood core are meshed using brick elements with single integration points. These results were then compared with experimental data obtained from three layer S-2 glass/epoxy facesheets balsa core sandwich structures. An excellent correlation between experimental and numerical results had been established.

• LS-DYNA® Material Model 263 and Its Application to Earing Predictions in Cup-Drawing

  Jinglin Zheng, Xinhai Zhu (Livermore Software Technology, an ANSYS company), Yanshan Lou (Xi’an Jiao Tong University), Saijun Zhang (South China University of Technology), Jeong Whan Yoon (Korea Advanced Institute of Science and Technology (KAIST)

  This paper introduces a newly implemented metal forming material model, material type 263, in LS-DYNA material library. The yield function of this model is based on a recent theoretical development of extending the original Drucker function into an anisotropic form. The flexibility of the yield function is further improved by adopting the non-associated flow rule. The paper also outlines how to use LS OPT® to calibrate the material parameters used in the model, followed by a cup-drawing analysis which demonstrates the model’s capability of capturing the cup earing profile, especially when paired with LS-OPT for material parameter identification.

• LS-DYNA® Performance and Scalability On Sun(TM) x64 Systems

  Michael A. Burke, Youn-Seo Roh, Henry H. Fong - Sun Microsystems, Inc.

  This paper describes AMD Opteron -based x64 systems of Sun Microsystems(TM), primarily the server (TM) family. Performance and scalability are shown for the refined Neon standard LS-DYNA benchmark problem – for both gigabit Ethernet and Cisco/Topspin(TM) InfiniBand(TM/SM) interconnects. The Sun Fire(TM) X2100 server, which can be easily installed in a Sun Grid Rack System, is seen to be a very attractive solution based on price- performance considerations. A continued effort on improving LS-DYNA performance on Solaris x64 platform is described. A brief mention is made of future benchmark work planned.

• LS-DYNA® Performance in Side Impact Simulations with 100M Element Models

  Alexander Akkerman, Yijung Chen, Bahij El-Fadl, Omar Faruque, Dennis Lam (Ford Motor Company)

  LS-DYNA has been used for vehicle crash simulations for many years. The models have increased in size over the years but in most cases do not exceed more than a few million elements. However, recently developed material models require much greater levels of refinement resulting in much larger models, perhaps as high as 100M elements. Simulating models of the order of 100M elements in turn requires much higher levels of scalability in order to be feasible in the vehicle development process. This paper will analyze LS-DYNA performance with a 100M-element sled side impact model running on up to 1,000 and more CPUs with various Intel processors and Infiniband interconnect technologies.

• LS-DYNA® Performance on 64-Bit Intel® Xeon® Processor-Based Clusters

  Tim Prince, Hisaki Ohara, Nick Meng - Intel Software and Solutions Group

  Benchmark performance of a cluster based on the newly introduced 64-Bit Intel® Xeon® Procesessor-based clusters is presented. Car2car and 3cars benchmarks from topcrunch.org are evaluated, using OpenIB based interconnects. Effect of shared memory options under Intel® MPI is evaluated. Improvement from optimizing 3cars P-file decomposition is demonstrated. Intel® Cluster Tools profiler is discussed.

• LS-DYNA® Performance on Intel® Scalable Solutions

  Nick Meng, Michael Strassmaier, James Erwin, Intel;, Jason Wang, LSTC

  Along with the Intel® Purley platform launch, a series of cost-effective products such as the Intel® Xeon® processor Scalable Family (formerly code-named Skylake-SP), Intel® Omni-Path Architecture fabric, Intel® SSDs, Intel® MPI 2018 library, and Intel® Math Kernel Libraries (MKL) have been released in 2017. In this paper we study and evaluate the impact of these Intel products on LS-DYNA application. Numerous factors affect application performance and must be investigated and understood to ensure top performance and value to our customers. Intel has characterized LS-DYNA Explicit and Implicit scalability performance through extensive benchmarking and has determined the optimal factors to be considered for the Intel® Omni-Path Architecture fabric, Intel® MPI, Intel MKL and the Skylake-SP processor.

• LS-DYNA® R7 : Free Surface and Multi-phase Analysis for Incompressible Flows

  Facundo Del Pin, Iñaki Çaldichoury, Rodrigo R. Paz (LSTC)

  LS-DYNA R7 introduced an incompressible flow solver which can track flow interfaces such as free surfaces or the interface between two fluids. Several industrial applications may be simulated with these features. In the area of free surface flows the effects of the lighter phase are neglected, i.e. in the case of water-air interfaces the air could be ignored if its effect does not change significantly the dynamics of the water phase. Some typical problems are wave propagation, dam break, sloshing problems and green water on decks. On the other hand problems where both phases should be taken into account are mixing problems, bubble dynamics and lubrication problems among others. In this work examples of both problems will be presented and explained. The set up process as well as the post processing will be detailed. Validation examples will be shown and compared to analytical or experimental solutions. Finally the current development status for some of the multiphase features will be discussed.

• LS-DYNA® R7: Conjugate heat transfer problems and coupling between the Incompressible CFD (ICFD) solver and the thermal solver, applications, results and examples.

  Iñaki Çaldichoury, Facundo Del Pin (LSTC)

  LS-DYNA version R7 includes CFD solvers for both compressible and incompressible flows. The incompressible CFD solver (ICFD) may run as a stand alone CFD solver for pure thermal fluid problems or it can be strongly coupled using a monolithical approach with the LS-DYNA solid thermal solver in order to solve the complete conjugate heat transfer problem. This paper will focus on the thermal part of the ICFDthermal and conjugate heat transfer problems will beillustration and discussion purposes. solver and its associated features. Several results of presented as well as some industrial applications for

• LS-DYNA® R7: Coupled Multiphysics analysis involving Electromagnetism (EM), Incompressible CFD (ICFD) and solid mechanics thermal solver for conjugate heat transfer problem solving

  Iñaki Çaldichoury, Pierre L'Eplattenier, Facundo del Pin (LSTC), Miro Duhovic (Institut für Verbundwerkstoffe GmbH)

  LS DYNA R7’s new modules and capabilities include: two fluid mechanics (CFD) solvers for incompressible (ICFD) and compressible flows (CESE) and an Electromagnetism solver (EM). The objective of these solvers is not only to solve for their particular domain of physics but to make full use of LS-DYNA capabilities and material library in order to solve coupled multiphysics. This paper will present how the EM solver can solve inductive heating problems, the problematic that arises when cooling the heated materials and/or coils is needed and how the ICFD solver can be used in conjunction in order to solve the complete EM-conjugate heat transfer problem. For illustration purposes, an industrial application studied at the Institut für Verbundwerkstoffe (See “Advances in simulating the processing of materials by electromagnetism induction” paper) will be introduced and discussed.

• LS-DYNA® R7: Recent developments, application areas and validation results of the compressible fluid solver (CESE) specialized in high speed flows.

  Zeng-Chan Zhang, Iñaki Çaldichoury (LSTC)

  LS-DYNA version R7 includes CFD solvers for both compressible and incompressible flows. The compressible flow solver is based on the CESE method, a novel numerical method for solving conservation laws. It has many nontraditional features such as space-time conservation, second order accuracy for flow variables and a powerful shock wave capturing strategy. This paper will focus on some advanced features of the solver namely its FSI capabilities. Several potential industrial applications will be presented such as airbag openings, piston type applications and turbomachines. Some results on high speed supersonic flows will also be presented for illustration and discussion purposes.

• LS-DYNA® R7: Strong Fluid Structure Interaction (FSI) capabilities and associated meshing tools for the incompressible CFD solver (ICFD), applications and examples.

  Facundo Del Pin, Iñaki Çaldichoury (LSTC)

  LS-DYNA version R7 includes CFD solvers for both compressible and incompressible flows. The solvers may run as standalone CFD solvers or they could be coupled to the LS-DYNA solid mechanics and thermal solvers for fluid structure interaction (FSI) and conjugate heat transfer problems. This paper will focus on the Incompressible CFD solver in LS-DYNA (ICFD) and its Fluid-solid interaction capabilities (FSI). Fluid structure interaction problems occur in physics whenever the flow over a structure causes deformation or displacement which in turn may influence the way how the fluid behaves. One of WKH VROYHU¶V PDLQ IHDWXUHV LV WKH LPSOHPHQWDWLRQ RI D UREXVW VWURQJ )6, FRXSOLQJ ZKLFK RSHQV D ZLGH QHZ range of applications in the range of aerodynamics, hydrodynamics, hemodynamics and so forth. Several examples will be provided for illustration and discussion. The ICFD solver is the first in LS-DYNA to make use of a new volume mesher that takes surface meshes bounding the fluid domain as input. For FSI problems that involve big displacements, the volume mesher algorithms need to be robust and flexible. Some of the latest developments and mesh control tools that are made available for the user will therefore also be introduced.

• LS-DYNA® R7: The ICFD Solver for Conjugate Heating Applications

  Iñaki Çaldichoury, Facundo Del Pin, Rodrigo R. Paz (LSTC)

  LS-DYNA version R7 introduced an incompressible flow solver (ICFD solver) which may run as a standalone CFD solver for pure thermal fluid problems or it can be strongly coupled using a monolithically approach with the LS-DYNA solid thermal solver in order to solve complex conjugate heat transfer problems. Some validation results for conjugate heat transfer analyses have been presented at the 9th European LS-DYNA Conference (2013) [1]. This paper will focus on a new output quantity, the heat transfer coefficient or ‘h’ which has recently been implemented in the ICFD solver. Its description, calculation and uses will be presented as well as some validation results.

• LS-DYNA® Scalability Analysis on Cray Supercomputers

  Ting-Ting Zhu (Cray Inc.), Jason Wang (LSTC)

  For the automotive industry, car crash analysis by finite elements is crucial to shortening the design cycle and reducing costs. To increase the accuracy of analysis, in additional to the improvement in finite element technique, smaller cells of finite element meshes are used to better represent the car geometry. The use of finer mesh coupled with the need for fast turnaround has put increased demand on scalability of the finite element analysis. In this paper, we will use the car2car model to measure LS-DYNA scalability on Cray® XC30™ supercomputers, an Intel ® Xeon® processor-based system using the Cray Aries network. The scalability of different functions in LS-DYNA at high core counts will be analyzed. The MPI communication pattern of LS-DYNA will also be studied. In addition to that, we will also explore the performance difference between using one thread per core and two threads per core. Finally, we will explore the performance impact of using large Linux Huge Pages.

• LS-DYNA®R7:Update On The Electromagnetism Module (EM)

  Pierre L'Eplattenier, Iñaki Çaldichoury, Julie Anton (LSTC)

  An electromagnetism module is being developed in LS-DYNA version R7 double precision for coupled mechanical/thermal/electromagnetic simulations. The physics, numerical methods and capabilities of this module will be introduced. Some examples of industrial applications will be presented. These include magnetic metal forming, bending and welding in different configurations, high pressure generation for equation of state studies and material characterization, induction heating, resistive heating, short circuits due to crashes, electromagnetic launchers, ring expansions, magnetic levitation and so forth. Additionally, magnetic material capabilities are currently available for beta testing and will also be discussed in this paper.

• LS-DYNA-Brochure.pdf
• LS-DYNA’s Linear Solver Development — Phase 2: Linear Solution Sequence

  Allen T. Li, Ford Motor Company;, Zhe Cui, Yun Huang, Livermore Software Technology Corporation

  This paper continues with the last one from the same authors on validating LS-DYNA’s linear solver development on elements (Phase1: Element Validation). In this paper, a simple plate model is used as the benchmark example for validation on linear solution sequence. The linear solutions from NASTRAN: SOL101 (static analysis), SOL103 (normal mode analysis), SOL108 (direct frequency response), SOL109 (direct transient response), SOL111 (modal frequency response) and SOL112 (modal transient response) are performed on this model. Equivalent linear analysis functions from LS-DYNA (static analysis, normal mode analysis, SSD, modal transient dynamics, etc.) are also performed. The results such as displacements, natural frequencies and stresses from NASTRAN and LS-DYNA are compared.

• LS-DYNA’s Linear Solver Development — Phase1: Element Validation Part II

  Allen T. Li, Ford Motor Company;, Zhe Cui, Yun Huang, Livermore Software Technology Corporation

  This paper continues with the last one from the same authors on validating LS-DYNA’s linear solver development on elements (Phase1: Element Validation Part I). In this paper, the R-type elements and bushing elements are investigated. The R-type elements include both rigid (RBE2, etc.) and interpolation elements (RBE3, etc.), which are very popularly used elements. The bushing (generalized spring and damper) elements consist of the CBUSH and CBUSH1D. Several benchmark examples are studied to perform cross-validation of the R-type and bushing elements in LS-DYNA and NASTRAN, in different types of analysis such as static, normal mode and SSD analysis.

• LS-DYNA’s Linear Solver Development — Phase 1: Element Validation

  Allen T. Li, Ford Motor Company;, Zhe Cui, Yun Huang, Livermore Software Technology Corporation

  LS-DYNA is a well-known multi-purpose explicit and implicit finite element code. It is mainly used to analyze the nonlinear response of structures. To answer increasing requests from users, LSTC is taking a big effort to develop and improve the linear solution capabilities in LS-DYNA. As part of this endeavor, a joint project was launched between Ford and LSTC to validate the linear solvers in LS-DYNA. In this project, a bunch of benchmark examples are tested using LS-DYNA and commercial code NASTRAN and the results are compared. The NASTRAN results are provided by Ford Motor Company. The purpose of this study is to: 1) validate the linear solution provided by LS-DYNA; and 2) identify the corresponding elements, material models, boundary conditions, loading types, and solution types in LS-DYNA which have the best match with the counterparts in NASTRAN. This provides us also a great opportunity to check which solvers of linear analysis are available in LS-DYNA and are ready for the users, and which are still missing and need further development.

• LS-DYNA: Status and Development Plan

  John Hallquist, Yun Huang, Iñaki Çaldichoury, Jason Wang (LSTC)

  Recent enhancements – John Hallquist Linear solver – Yun Huang LS-PrePost: ICFD & EM – Iñaki Çaldichoury Particle methods – Jason Wang

• LS-OPT ® Status and Outlook

  Nielen Stander and Anirban Basudhar (LSTC)

  Features added to the recently released LS-OPT Version 5.2 are discussed. An outlook of the next version, which includes Statistical Classification and Digital Image Correlation, is given.

• LS-OPT based identification of a user defined material model for distortional hardening with application to sheet forming processes with complex strain path changes

  Vladislav Levkovitch, Bob Svendsen - University of Dortmund

  Sheet metal forming involves large strains and severe strain path changes. Large plastic strains lead in many metals to the development of persistent dislocation structures resulting in strong flow anisotropy. This induced anisotropic behavior manifests itself in the case of a strain path change by very different stress-strain responses depending on the type of the strain path change. While many metals exhibit a drop of the yield stress (Bauschinger effect) after a load reversal, some metals show an increase of the yield stress after an orthogonal strain path change (so-called cross hardening). To model the Bauschinger effect, kinematic hardening has been successfully used for years. However, the usage of the kinematic hardening leads automatically to a drop of the yield stress after an orthogonal strain path change contradicting experimental results for materials exhibiting the cross hardening effect. Another effect, not accounted for in the classical elasto-plasticity, is the difference between the tensile and compressive strength, exhibited e.g. by some steel materials. In this work we present a phenomenological material model whose structure is motivated by polycrystalline modeling that takes into account the evolution of polarized dislocation structures on the grain level – the main cause of the induced flow anisotropy on the macroscopic level. The model considers besides the movement of the yield surface and its proportional expansion, as it is the case in conventional plasticity, also the changes of the yield surface shape (distortional hardening) and accounts for the pressure dependence of the flow stress. All these additional attributes turn out to be essential to model the stress-strain response of high strength steels subjected to non-proportional loading. The model is implemented into LS-DYNA via the user material interface. After an LS-OPT based parameter identification for a dual phase high strength steel with the help of one- and two-stage loading tests, we demonstrate the capability of the model to predict the spring-back in processes with complex strain path changes.

• LS-OPT Capabilities for Robust Design

  Nielen Stander, Willem Roux - Livermore Software Technology Corporation

  This paper presents a number of new features available in LS-OPT Version 2.2. As a step toward robust design, the code has been extended to enable reliability assessment and the identification of sources of unpredictability in the FE model. In the latter feature, deterministic and stochastic effects can be separated.

• LS-OPT Parameters Identification on Concrete Sample Tests for an Impact Simulation on Concrete Slab

  Nicolas Van Dorsselaer, Vincent Lapoujade (DynaS+), Georges Nahas, Bertrand Ciree, François Tarallo, Jean-Mathieu Rambach (Institut de Radioprotection et de Sûreté Nucléaire)

  The dynamic behavior of Concrete is one of the most common and difficult problem of simulation in Nuclear, Defense and Civil fields. In most cases, the data available for modeling problems is much reduced; engineers are obliged to predict the behavior with non sufficient information. Due to this lack of experimental sample based input parameters, the result of simulation becomes “engineer dependent”, leading to much different results than people doing the same modeling problem. In previous paper ([5], [6]) presented during last LS-DYNA Conferences, we showed that a probabilistic approach for concrete modeling can be used to reduce these differences due to the modeling choices. But one of the main conclusions of these papers was that all these modeling techniques never replace experimental concrete sample tests to obtain the right material behavior before simulation. This paper is based on a work realized for an international OECD benchmark initiated by IRSN and CNSC. The main goal of IRIS_2012 Benchmark was to evaluate the ability of simulation to reproduce experimental tests of impacts on concrete slabs. Contrary to the earlier benchmark (IRIS_2010), experimental results of concrete sample tests was this time available in order to calibrate numerical constitutive laws before simulations on real tests. This paper, as the rest of our previous papers about IRIS_2010, will present the use of LSTC products capabilities in this kind of approach. In a first time, a complete LS-DYNA concrete model based on compressive strength will be created using automatic parameters generation capabilities of LS-DYNA. Then this model will be compared to experimental sample results of several cylindrical sample tests (simple compression and confined compressions at several confinement pressures). After sensitivity analysis to identify which parameters of the concrete model can be used to fit experimental results, LS-OPT parameters identification will be performed simultaneously on all cases. Based on the VTT Punching test simulation of IRIS_2012, we will compare the results between simulation with parameters automatically generated, simulation with fitted parameters and experiment. This comparison will be focused on missile velocity after impact and slab concrete damage. We precise that all the calculations presented here are performed with LS-DYNA solver, coupled with LS-OPT software for the probabilistic part of the studies (DoE studies, Monte Carlo Analysis, Robustness and Optimizations).

• LS-OPT Version 5: A New Flowchart-Based Interface for Process Simulation and Optimization

  D. Björkevik, C. Belestam (DYNAmore Nordic), K. Witowski(DYNAmore GmbH), N. Stander (LSTC), T. Eggleston (Leawood)

  ®This paper provides an overview of the new flowchart-based interface for LS-OPT . The primary purpose of this development was to provide an interface for process simulation and optimization. An example of a manufacturing process is used to demonstrate problem setup and GUI functionality.

• LS-OPT® Status Update

  N. Stander, A. Basudhar (Ansys/LST)

  LS-OPT Version 7.0 was released in November 2020 with several new features which are briefly summarized here:

• LS-OPT®: New Developments and Outlook

  Nielen Stander and Anirban Basudhar (LSTC)

  New features available in LS-OPT® 5.1 are discussed and illustrated. The main features include three new solver types, Parallel Feedforward Neural Networks, seamless variable de-activation for iterative methods, exporting of selected metamodel formulae, subregion-based Global Sensitivity Analysis, enhanced histogram visualization features and Viewer-based categorization of simulation results.

• LS-OPT/Topology Version 1

  Willem Roux, Tushar Goel - Livermore Software Technology Corporation, David Björkevik - Engineering Research AB

  This paper presents LS-OPT/Topology, a new topology optimization tool. Topics such as its capabilities, current development directions, and integration into an industrial design environment are discussed.

• LS-TaSC 4: Designing for the Combination of Impact, Statics and NVH

  K. Witowski (DYNAmore)

  The projected subgradient method is major new methodology development for the topology optimization of huge, multi-disciplinary structural problems; for example, the combined impact, statics, and NVH design of a whole body in white. This paper accordingly discusses the projected subgradient method in LS-TaSC 4, with specific reference to the basic theory, the ability to combined impact and NVH load cases, and the performance for huge models. Also mentioned is how the method has been enhanced to handle generalized constraints using the multi-tensor numerical scheme.

• LS-TaSC Product Status

  K. Witowski, P. Schumacher (Dynamore), W. Roux (LSTC)

  The LS-TaSC Version 3.1 topology and shape design tool is presented. The presentation introduces the multi-point numerical derivatives scheme that allows constrained optimization using the mass fractions and load case weights as variables. This allows constrained optimization using any response or mathematical expressions as constraints or objectives.

• LS-TaSC Product Status

  K. Witowski (DYNAmore); W. Roux (LSTC)

  The LS-TaSC Version 3.2 topology and shape design tool is presented. The presentation introduces the multi-point numerical derivatives scheme that allows constrained optimization using the mass fractions and load case weights as variables. This allows constrained optimization using any response or mathematical expressions as constraints or objectives. In addition, the capabilities currently under development such as designing to maximize the fundamental frequency and new geometry definitions will also be presented. All these capabilities will be illustrated using examples.

• LS-TaSCTM Version 2

  W. Roux (LSTC)

  This paper gives an overview of LS-TaSC version 2.1, a topology optimization tool using LS-DYNA® for the analysis of nonlinear structural behavior. The focus is on its capabilities, current development directions, and integration into an industrial design environment. Examples of using the new developments such as dynamic load scaling are given.

• LSTC / NCAC Dummy Model Development

  Pradeep Mohan, Chung-Kyu Park, Dhafer Marzougui, Cing-Dao Kan - The George Washington University, Sarba Guha, Christoph Maurath, Dilip Bhalsod - Livermore Software Technology Corporation

  This paper presents the modeling and validation status of the most commonly used crash test dummies in the regulatory and consumer crash test programs, the Hybrid III family of crash test dummies. Systematic modeling and validation procedures are established and adopted to ensure the accuracy, efficiency, robustness, and ease of use of the models. The procedures are based on the premise that the model must be based on the fundamentals of mechanics, focusing directly on component geometry and material mechanical properties. The dummy models are created and validated at the component level. The models are then integrated and re-evaluated at the system level. The paper presents the component and system level validation results of the HIII 50th and 5th percentile dummy models.

• Machine Learning Approaches for Repositories of Numerical Simulation Results

  Prof. J. Garcke, R. Iza Teran (Fraunhofer SCAI)

  Simulations are used intensively in the developing process of new industrial products and have achieved a high degree of detail. In that workflow often up to thousand finite element model variants, representing different product configurations, are simulated within a few days. Currently the decision process for finding the optimal product parameters involves the comparative evaluation of large finite element simulation bundles by post-processing each one of those results using 3D visualization software. This time consuming process creates a severe bottleneck in the product design and evaluation workflow.

• Machine learning using a hybrid quantum-classical algorithm

  Maximilian Spiegel, Sebnem Gül-Ficici, Ulrich Göhner

  The industrial sector uses artificial intelligence (AI) in many ways. E.g. anomaly detection to identify and examine abnormal behavior of machines, such as voltage and current fluctuation. To develop self driving cars AI is used to perform segmentation of the environment to navigate the vehicle and make decisions, preferably in real-time. Quantum computers are already being used for special machine learning processes, achieving, in some instances, better results than a regular machine learning algorithm. This paper will elaborate on the upsides of a machine learning model consisting of a hybrid between a quantum machine learning (QML) algorithm and a classical machine learning algorithm.

• Macroscopic Modeling of Flow-Drill Screw Connections

  J. K. Sønstabø, D. Morin, M. Langseth (Norwegian University of Science and Technology)

  In the last decades, the use of polymeric materials in the automotive industry has increased dramatically. This demand is linked to the good ratio between cost, density and mechanical properties for this class of materials . Moreover, injection modelling allows a very large range of shapes for the polymeric parts used in a car body. This combination of advantages makes polymers an ideal choice for automotive applications such as interior body parts as well as exterior bumpers.

• Macroscopic Modeling of Flow Drill Screw Connections

  J. K. Sønstabø, D. Morin, M. Langseth (Norwegian University of Science and Technology)

  Flow-drill screws (FDS) are used in the automotive industry to join parts in the load-bearing structure of cars. The process is a simple one-step procedure, which requires access only from one side of the assembly, and a variety of dissimilar materials may be joined. As it is easy to automate, the FDS technology is well suited for the production lines in the automotive industry.

• MADYMO and LS-DYNA; the Strength of a Combined Approach

  F. Schoenmakers - TASS

  While safety legislation becomes more stringent and vehicles intended for global markets must conform to the requirements of a wider range of regulatory bodies, the cost of physically testing crash safety performance continues to rise and the vehicle safety system design is under high pressure to adopt virtual development techniques. Structural analysis and safety system optimization have traditionally been undertaken in two totally different computational environments. MADYMO is the worldwide standard occupant safety simulation software. It is renowned for its fast simulations, high-quality dummy models, and accurate restraint system modelling techniques. LS- DYNA is known for its accurate and robust structural FE calculations, optimizing the vehicle structure for crash integrity and deceleration levels. This presentation describes the mechanism to couple MADYMO and LS-DYNA to take full benefit of the best of these two worlds to further enhance the performance of vehicle safety performance designs. Due to the large number of simulations required, restraint system design and optimization can be done in MADYMO, using input from FE analyses and/or tests. The MADYMO dummy + optimized restraint design can then be implemented in the LS-DYNA vehicle model to verify and fine- tune the restraint performance in the full vehicle crashworthiness analyses. The use of the same MADYMO dummy model in the total design process ensures a transparent and controlled manner of judging the restraint performance. Typical use case examples will be presented to show the benefit of the combination of MADYMO and LS-DYNA.

• MADYMO and LS-DYNA; the Strength of a Combined Approach

  F. Schoenmakers - TASS

  While safety legislation becomes more stringent and vehicles intended for global markets must conform to the requirements of a wider range of regulatory bodies, the cost of physically testing crash safety performance continues to rise and the vehicle safety system design is under high pressure to adopt virtual development techniques. Structural analysis and safety system optimization have traditionally been undertaken in two totally different computational environments. MADYMO is the worldwide standard occupant safety simulation software. It is renowned for its fast simulations, high-quality dummy models, and accurate restraint system modelling techniques. LS- DYNA is known for its accurate and robust structural FE calculations, optimizing the vehicle structure for crash integrity and deceleration levels. This presentation describes the mechanism to couple MADYMO and LS-DYNA to take full benefit of the best of these two worlds to further enhance the performance of vehicle safety performance designs. Due to the large number of simulations required, restraint system design and optimization can be done in MADYMO, using input from FE analyses and/or tests. The MADYMO dummy + optimized restraint design can then be implemented in the LS-DYNA vehicle model to verify and fine- tune the restraint performance in the full vehicle crashworthiness analyses. The use of the same MADYMO dummy model in the total design process ensures a transparent and controlled manner of judging the restraint performance. Typical use case examples will be presented to show the benefit of the combination of MADYMO and LS-DYNA.

• Magnet dynamics using LS-DYNA®

  T. Nguyen, I. Caldichoury, P. L'Eplattenier (Ansys/LST), L. Kielhorn, T. Rüberg, J. Zechner (Tailsit)

  The LS-DYNA® Electromagnetic solver (EM) has recently integrated a new monolithic FEM (Finite Element Method) – BEM (Boundary Element Method) solver along with an AMS (Auxiliary Maxwell Space) preconditioner. Eddy-Current and Magnetostatic - including linear or non-linear magnetic materials - analysis can be done thanks to these new implementations [1]. On top of this, the capability to have permanent magnets has been introduced. We will start by showing a benchmark between LS-DYNA® and ANSYS Maxwell on the force calculation between two magnets in different conditions. The first model consists of two-cylinder magnets at a distance d. The magnet is a Neodymium Iron Boron magnet with a magnetic coercivity of -900 kA/m. In the first comparison, a linear magnetic characteristic of the magnet is considered. Then a non-linear BH curve is introduced in the next comparison. The insulator is a linear material with no conductivity. In the second model, we added a steel plate with high permeability between the 2 magnets to see its influence on the force on each magnet. The benchmark gives a good agreement between Ansys-Maxwell and LS-DYNA® in terms of results and computational cost in both linear and nonlinear case.

• Mainframe Computer Connector Wear Correlation and Prediction Analysis

  I. Karpov, I. Demiyanushko, B. Tavshavadze (Moscow Automobile and Road Construction State Technical University (MADI)

  Mainframe computers are expected to be highly reliable and available. To achieve this high level of reliability and availability, care must be taken from the initial development cycles to insure robust software and hardware. Here, the discussion will be focused on the structural aspect, namely the hardware assembly. A mainframe computer’s hardware structure consists of the rack, processor drawer, cooling assembly, input and output (I/O) assembly, power supply assembly, memory assembly and storage drawers. A typical mainframe computer with a single drawer installed is shown in Figure 1. The total height is 2.0 m where a total of 42 units (U) of many different types of mountable assemblies or drawers can be installed in the rack; 1U is 44.45 mm in vertical height. The height of the assemblies varies from 88 mm to 440 mm. The rack is an EIA (Electronic Industries Alliance) standard 19-inch-wide rack (482.6 mm), where the actual width of the mounting rails where the assemblies or server drawer is installed is 17 ¾” (450.85 mm). The total width of the rack is equal to 600 mm, which provides space to accommodate the cabling and vertical structure outside the width of the server drawer. The rack depth is 1070 mm. The drawer shown in Figure 1 is a 4U server drawer installed in the bottom of the rack, with a total drawer mass of 73 kg.

• Making FEM Tire Model And Applying It For Durability Simulation

  Masaki Shiraishi, Hiroshi Yoshinaga, Naoaki Iwasaki, Sumitomo Rubber Industries - LTD, Kimihiro Hayashi - The Japan Research Institute,Ltd

  In recent years, CAE (Computer Aided Engineering) has become very popular for effective development of many industrial products. In the development of automobile, CAE has been applied in many fields. About endurance and fatigue analyses of automobile, it is necessary to simulate the force by road input, and accurate tire model is necessary for this. But the construction of tire is very complicated and its model is so complicated that large calculation resource is necessary. Such a simulation is not useful for actual automobile development. Then we tried making simplified tire simulation model that express the tire properties of minimum requirement. After developing tire model, we applied the model to curb striking simulation to confirm the availability of the model.

• Making HPC Accessible for SMEs

  A. Wierse (Sicos BW)

  Numerical computation, often also named simulation, plays nowadays in many enterprises an important role in the development process. Especially in large companies in the automotive or aerospace industry it is actually impossible to develop a new product without simulation technology. In recent decades the necessary know-how and personnel has been built up, but there have also been and will be significant investments into the infra structure. Investments of a size, that can easily be handled by large companies, can be a real challenge for an SME.

• Manage multi-disciplinary load cases in SDM: Model setup and evaluation of results

  Andreas Lohbrunner, Marko Thiele

  Due to the continuously increasing demand in Computer Aided Engineering (CAE), it is essential for high efficiency and transparency to automate and standardize processes. In many cases, Simulation Data Management (SDM) software is used for this purpose. To achieve all mechanical target values of a product, there are several standard disciplines in the field of CAE, such as Crash, Noise Vibration Harshness (NVH) or Fatigue. Assembly, solving and postprocessing for these disciplines can differ greatly from one another. For this reason, it is best practice in many companies to carry out the optimization of a model in each discipline separately and to compare the results and structural adjustments with other disciplines at regular intervals.

• Manufacturing Simulation as Part of the Digital Prototype

  P. Böhler, J. Dittmann, D. Michaelis, P. Middendorf (Universität Stuttgart); C. Liebold (DYNAmore)

  The research project Active Research Environment for the Next generation of Automobile (ARENA2036) is a long term project funded by the Federal Ministry of Education and Research Germany. Within this project four sub-projects are located. DigitPro, one of those sub-projects, deals with the development of a Digital Protoype. A closed simulation process chain is built which not only covers different simulation disciplines such as crushing or process analysis, but also various software solutions and material models. The main goal is to use the digital prototype to decrease the weight if an automotive structure by 10% and the development time by 50%. In this project one of the focused manufacturing processes for composite structures is the braiding technology followed by an infusion process. A complete numerical prediction is necessary for the braiding as well as for the infiltration process to decrease the development time and to increase the mechanical performance of braided structures. Within this work an overview of the newest developments in braiding and infiltration simulation and especially in the transfer of the necessary data from one process to the next is given. An overview on the succeeding project “Digital Fingerprint” will be given as the results of the project DigitPro will be used there.

• Manufacturing Simulation of an Automotive Hood Assembly

  Chris Galbraith, Dylan Thomas - Centre for Automotive Materials and Manufacturing currently with Honda R&D Americas, Inc., Mark Finn - Alcan International Ltd.

  This paper presents the results of applying the finite element method to calculating the spring back of an automotive hood assembly, and its application to the functional build method. The assembly was comprised of six individual panels: an inner panel, an outer panel, a major reinforcement, a latch reinforcement, and two hinge reinforcements. Finite element simulations were conducted for forming each of the six components. Each component was formed, trimmed, and positioned in car position. The outer panel required several secondary forming operations including a re-meshing, remapping, trim, and flanging operation. Once in car position, the components were moved so that they just contacted each other, and were “spot welded” together through the application of nodal constraints. Mastic between components was simulated with tied contact. Contact between components was simulated with contact interfaces. Finally, a spring back analysis was conducted. The models clearly illustrate that it is possible to predict spring back of large automotive assemblies, and that the assembly process yields different final shapes than those obtained from spring back of individual components. With this newly developed tool it is possible to predict whether or not the assembly process can correct out-of-spec components, a key factor in utilizing the functional build method.

• Manufacturing the London 2012 Olympic Torch

  Trevor Dutton, Paul Richardson (Dutton Simulation Ltd)

  A key part of the build-up to the London 2012 Olympic Games was the Torch relay for which each one of the 8,000 runners required a Torch. The design of the Torch comprised inner and outer skins of perforated aluminium formed into a triangular cross-section, which flared out towards the top to house the gas burner. Dutton Simulation was asked to assist with development of a process to manufacture the skins to the required accuracy and quality of finish; some of the key technical challenges are described in the paper. The first task was to develop a blank shape for the two forms and then confirm these with incremental forming simulation (using eta/DYNAFORM with the LS-DYNA® solver). The validated shapes – both the profile and the thousands of holes – were then cut by laser. In conjunction with developing the blank, the optimum forming process also had to be determined, to form the perforated sheet to the accuracy required for laser welding the joining seam. Several process concepts were explored before arriving at a four stage method. With aluminium as the raw material springback was already expected to be a factor; this was compounded by the holes further reducing the material stiffness and the relatively low strain in the form due to the large radii. Nonetheless, the geometry had to be formed to a very tight tolerance, both for the weld process and also to create a result free of cosmetic defects. LS-DYNA was used to determine the springback at each step of the forming process (Figure 1) and the springback compensation solution was used to provide the correction. DYNAFORM’s tools for cosmetic defect detection (stoning, reflect lines) were employed to check the result to the highest level of detail.

• Marine Accident Integrated Analysis System using Highly Advanced M&S System of FSI Analysis Technique

  S. Lee, J. Lee, J. Park, T. Jung (Korea Maritime & Ocean University)

  Investigation of marine accident causes usually depends on the judgments of maritime experts, based on the statements of the concerned persons in the case where there is no navigation equipment, such as AIS and VDR. Scientific verification also has a limitation in the case of their conflicting statements. It is necessary to develop Marine Accident Integrated Analysis System (MAIAS) using highly advanced Modeling & Simulation (M&S) system of Fluid-Structure Interaction (FSI) analysis technique for the scientific investigation of marine accident causes and for the systematic reproduction of accident damage procedure. To ensure an accurate and reasonable prediction of marine accident causes, full-scale ship collision, contact, grounding, flooding, capsize, sinking and turning simulations would be the best approach using hydrocode, such as LS-DYNA, with its FSI analysis technique, propulsion force for ship velocity, and rough sea weather such as current, strong wind and wave with irregular spectrums. The objective of this paper is to present the findings from full-scale ship collision, grounding, flooding, capsize, sinking and rapid turning simulations of marine accidents, and to demonstrate the feasibility of the scientific investigation of marine accident causes using MAIAS.

• MAT_291: A New Micromechanics-Inspired Model for Shape Memory Alloys

  J. Karlsson (DYNAmore Nordic) S. Kari, R. Dhume, S. Kashyap (Medtronic)

  This paper presents a new micromechanics-inspired constitutive model for shape memory alloys (SMAs) based on [1]. Shape memory alloys, e.g. Nitinol (Nickel-Titanium alloy), are widely utilized in the medical device industry because of their superelasticity. Superelastic properties of Nitinol enable its use in self-expanding stents and heart valve frames that can be inserted through a vein or artery using a thin delivery device and expanded at the target location. Motivated by the increased use of SMAs in the medical device industry, *MAT_291 (*MAT_SHAPE_MEMORY_ALLOY) is a first step towards more accurate and reliable material modeling. This material is currently available for solid elements and for explicit and implicit analysis. SMAs consist of two solid crystallographic phases, austenite (a high symmetry crystal structure, stable at high temperatures) and martensite (a low symmetry crystal structure that can be twinned or de-twinned, stable at low temperatures). Reversible transformation between the different phases gives rise to the shape-memory effect and superelasticity. The former implies that seemingly permanent deformation in the martensite phase can be recovered upon transformation to austenite by heating. The latter implies the material can undergo large strains in tension which can be recovered upon unloading. However, the superelastic stress-strain cycle will show elastic hysteresis similar to rubber-like materials, resulting from the transformation between twinned martensite, detwinned martensite, and austenite, see Figure 1.

• Matching LS-DYNA Explicit, Implicit, Hybrid Technologies with SGI Architectures

  O. Schreiber, T. DeVarco, S. Shaw (SGI), S. Bala (LSTC)

  LSTC has now integrated Explicit, Implicit solver technologies into a single hybrid code base allowing seamless switching from large time steps transient dynamics to linear statics and normal modes analysis. There are multiple computer architectures available from SGI to run LS- DYNA. They can all run LSTC solvers using Shared Memory Parallelism (SMP), Distributed Memory Parallelism (DMP) and their combination (Hybrid Mode) as supported by LS-DYNA. Because computer resources requirements are different for Explicit and Implicit solvers, this paper will study how advanced SGI computer systems, ranging from multi-node Distributed Memory Processor clusters to Shared Memory Processor servers address the computer resources required and what tradeoffs are involved. The paper will also outline the specifications of running LS-DYNA jobs on Cyclone, SGI’s HPC cloud computing infrastructure using d3View. d3View is a simulation data management and visualization software that extends the use of HPC by performing simulation data extraction and analysis on the compute nodes.

• Material Characterization of a 3D-Woven Carbon Fiber Preform at Macro-Scale Level for Manufacturing Process Modelling

  G. Scarlat, R.Ramgulam, P. Martinsson, H. Bayraktar (Albany Engineered Composites)

  The latest generation of CFM LEAP aero engines that power the Boeing 737-MAX and Airbus A320neo have their fan blades and fan-cases made out of 3D woven carbon fiber and epoxy composites. These composites are manufactured using preforms that are 3D woven and undergo a complex forming process during manufacturing prior to being injected with resin during the RTM process. The present paper showcases the work done at Albany Engineered Composites (AEC) to characterize and model the mechanical behavior of the 3D woven carbon-fiber preform at the macroscopic level with the purpose of simulating manufacturing processes. A variety of factors during such forming process can have a significant effect on the quality of the preform as it arrives at the RTM injection stage. A “good” preform quality usually means the absence of any wrinkles, high-shear areas and other similar local flaws at the end of the forming process, which in turn will have an effect on the performance of the molded part. The use of FE simulation tools can help predict such local defects, and allow (relatively cheap, in the virtual world realm) the exploration of some different combination of system and process parameters which will avoid such issues. The first task was to select the most appropriate material model that can adequately represent the 3D woven carbon fiber preform at the macro-scale level, in an FE model using shell elements. This approach was decided due to the fact that it is computationally impractical to model each tow at the meso-scale level due to the overall dimensions of the parts that are typically manufactured. Since there is no “universal” material model developed for 3D woven textiles, several built-in dry-fabric material models available in LS-DYNA were tested. The calibration of the material model parameters was done based on the fidelity of the model in matching the experimentally measured response of 3D woven preform coupons. For this purpose, an extensive set of coupon tests were conducted for in-plane behavior characterization. The main types of loading that the preform is subjected to during the forming operations are uni-directional tensile and shear. The draping behavior of material models considered is another important criteria and was evaluated as well. The current paper will detail all the above steps undertaken within the material characterization workflow and will present comparisons of LS-DYNA simulation against experimental results for representative tests of the 3D woven preform coupons.

• Material Constitutive Parameter Identification using an Electromagnetic Ring Expansion Experiment Coupled with LS-DYNA® and LS-OPT®

  Ismael Henchi, Pierre L’eplattenier, Nielen Stander - LSTC, Glenn Daehn, Yuan Zhang, Anupam Vivek - The Ohio State University

  In this paper, a parameter identification procedure to obtain the constitutive properties of metals at high strain rate and high temperature is presented. This procedure uses experimental results from electromagnetic ring expansions, coupled with LS-DYNA® simulations using the newly developed electromagnetism module, driven by LS-OPT®. The experiments were performed at The Ohio State University and the expansion velocities of the ring were measured. These are used as the target data for the optimization process where the constitutive properties are varied. The procedure is presented in details. It is then tested on a numerical case where the target velocity was generated by a simulation with given constitutive properties. Finally, it is used to find the constitutive properties of a copper alloy.

• Material Data Determination and Crash Simulation of Fiber Reinforced Plastic Components

  Florian Becker - German Institute for Polymers (DKI, Stefan Kolling - Institute of Materials and Applied Mechanics, THM, Julian Schöpfer - Daimler AG

  The quality of the mechanical simulation of reinforced thermoplastics depends on very com­ plex input parameters regarding the complex material behaviour. At the beginning of the sim­ ulation chain the material data has to be determined in different mechanical tests (tension, compression and shear, different fibre orientation to load direction, etc.). After the injection moulding simulation the calculated fibre orientation has to be mapped to the structural FE mesh. For the structural simulation a combination of the material model MAT108 and MAT54 was used to simulate the orthotropic, load case sensitive material behaviour.

• Material Model Development for Impact Strength Validation of a Composite Truck Bed Design

  Emily Nutwell, Dylan Thomas - Honda R&D Americas

  A recently developed pick-up truck has a unique bed structure which includes an under bed storage system. This truck bed and storage system design is made of sheet molded composite (SMC) material. SMC is a composite material where chopped glass fiber is laid on a poly(vinyl)ester sheet and run through a compaction process. SMC sheets are then loaded into a press to mold the desired part. During the molding process, certain design features such as molded-in ribs can cause the random orientation of the glass fibers to become directional, causing non- homogeneous material properties in the final product. A finite element material model of the SMC material was developed using material tests performed on flat SMC specimens and SMC specimens with molded-in ribs. This paper presents the details of the SMC material model development and application of the model to static and impact strength simulations on the truck bed design. The truck bed design did not include molded-in ribs, as simulations showed these ribs would crack during impact requirement tests. Furthermore, simulation was able to validate the final design prior to test without having to re- work the tooling.

• Material Model Evaluation of a Composite Honeycomb Energy Absorber

  K. E. Jackson (NASA Langley Research Center), E. L. Fasanella (National Institute of Aerospace), M. S. Annett (NASA Langley Research Center), M. A. Polanco (ATK Space Systems)

  Abstract A study was conducted to evaluate four different material models in predicting the dynamic crushing response of solid-element-based models of a composite honeycomb energy absorber, designated the Deployable Energy Absorber (DEA). Dynamic crush tests of three DEA components were simulated using the nonlinear, explicit ®transient dynamic code, LS-DYNA . In addition, a full-scale crash test of an MD-500 helicopter, retrofitted with DEA blocks, was simulated. The four material models used to represent the DEA included: *MAT_CRUSHABLE_FOAM (Mat 63), *MAT_HONEYCOMB (Mat 26), *MAT_SIMPLIFIED_RUBBER/FOAM (Mat 181), and *MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM (Mat 142). Test-analysis calibration metrics included simple percentage error comparisons of initial peak acceleration, sustained crush stress, and peak compaction acceleration of the DEA components. In addition, the Roadside Safety Verification and Validation Program (RSVVP) was used to assess similarities and differences between the experimental and analytical curves for the full-scale crash test.

• MATERIAL MODELING OF ORTHOPEDIC INSOLES

  S. Kolling, M. Neubert - Giessen University of Applied Sciences, J. Subke, J. Griesemann - Biomechanics Lab

  An experimental setup is presented for the material characterization of rubber-like sensomotoric insoles. This setup consists of local hardness measurements, quasi-static compression tests and dynamic testing using the 4a Impetus II pendulum test system [1]. A correlation between the measure of shore hardness and the stress strain relation of rubber-like materials is presented and verified in order to consider the inhomogeneous properties of insoles due to milling work of the manufacturing process. The dynamic response of the material is modeled by MAT_SIMPLIFIED_RUBBER/FOAM (material no. 181) in LS-DYNA [2] and MAT_SIMPLIFIED_RUBBER_WITH_DAMAGE respectively. The presented modeling technique is capable to describe the entire process chain from milling of the insole up to its usage. A further experimental setup is presented for converting the inlay and the human foot to a finite element model. By means of the Streifenlichttopometrie (SLT) [3] it is possible to record the complete surface of the object in a practically photorealistic fashion, i.e. three-dimensionally. In comparison with the classic method of photogrammetry, Streifenlichttopometrie is remarkably faster (10,000 points/s instead of 1 point/s). In this paper we present a modification of this method towards the measurement of dynamic processes.

• MATERIAL MODELING OF ORTHOPEDIC INSOLES

  S. Kolling, M. Neubert - Giessen University of Applied Sciences, J. Subke, J. Griesemann - Biomechanics Lab

  An experimental setup is presented for the material characterization of rubber-like sensomotoric insoles. This setup consists of local hardness measurements, quasi-static compression tests and dynamic testing using the 4a Impetus II pendulum test system [1]. A correlation between the measure of shore hardness and the stress strain relation of rubber-like materials is presented and verified in order to consider the inhomogeneous properties of insoles due to milling work of the manufacturing process. The dynamic response of the material is modeled by MAT_SIMPLIFIED_RUBBER/FOAM (material no. 181) in LS-DYNA [2] and MAT_SIMPLIFIED_RUBBER_WITH_DAMAGE respectively. The presented modeling technique is capable to describe the entire process chain from milling of the insole up to its usage. A further experimental setup is presented for converting the inlay and the human foot to a finite element model. By means of the Streifenlichttopometrie (SLT) [3] it is possible to record the complete surface of the object in a practically photorealistic fashion, i.e. three-dimensionally. In comparison with the classic method of photogrammetry, Streifenlichttopometrie is remarkably faster (10,000 points/s instead of 1 point/s). In this paper we present a modification of this method towards the measurement of dynamic processes.

• Material Modeling of Space Shuttle Leading Edge and External Tank Materials For Use in the Columbia Accident Investigation

  Kelly Carney, Matthew Melis - NASA Glenn Research Center, Edwin L. Fasanella - US Army Research Laboratory/VTD, Karen H. Lyle - NASA Langley Research Center, Jonathan Gabrys - Boeing

  Upon the commencement of the analytical effort to characterize the impact dynamics and damage of the Space Shuttle Columbia leading edge due to External Tank insulating foam, the necessity of creating analytical descriptions of these materials became evident. To that end, material models were developed of the leading edge thermal protection system, Reinforced Carbon Carbon (RCC), and a low density polyurethane foam, BX-250. Challenges in modeling the RCC include its extreme brittleness, the differing behavior in compression and tension, and the anisotropic fabric layup. These effects were successfully included in LS-DYNA Material Model 58, *MAT_LAMINATED_ COMPOSITE_ FABRIC. The differing compression and tension behavior was modeled using the available damage parameters. Each fabric layer was given an integration point in the shell element, and was allowed to fail independently. Comparisons were made to static test data and coupon ballistic impact tests before being utilized in the full scale analysis. The foam's properties were typical of elastic automotive foams; and LS-DYNA Material Model 83, *MAT_FU_CHANG_FOAM, was successfully used to model its behavior. Material parameters defined included strain rate dependent stress-strain curves for both loading and un-loading, and for both compression and tension. This model was formulated with static test data and strain rate dependent test data, and was compared to ballistic impact tests on load-cell instrumented aluminum plates. These models were subsequently utilized in analysis of the Shuttle leading edge full scale ballistic impact tests, and are currently being used in the Return to Flight Space Shuttle re-certification effort.

• Material Models for Thermoplastics in LS-DYNA® from Deformation to Failure

  P. Reithofer, A. Fertschej, B. Hirschmann, B. Jilka, M. Rollant, 4a engineering GmbH

  In the last years the demands of the automotive industry have led to a strong interest for a more detailed description of the behavior of thermoplastic materials and thus for more complex material cards including damage and failure. Also, the importance of gaining material data quickly has risen. Currently material and failure modeling in crash simulations typically deal with simple von Mises visco-plasticity (*MAT_024) and equivalent strain failure criteria, which cannot describe the complex material behavior of plastics. Past developments have focused on the yield behavior under different load situations (tension, shear, compression), which are implemented in more complex material models like *MAT_SAMP-1.

• Material Parameter Identification with LS-OPT

  K. Witwowski (DYNAmore)

  In this workshop a short introduction to LS-OPT will be given, and the application of LS-OPT for calibration of material parameters will be presented. The new LS-OPT version 6.0 features for the usage of digital image correlation data for calibration of material parameters will be discussed by means of an application example.

• Material Testing for Development and Calibration of Material models for Plastic Deformation and Failure

  Amos Gilat, Jeremy Seidt (The Ohio State University Department of Mechanical and Aerospace Engineering)

  Material testing at various, loading conditions, temperatures, and strain rates is used forstudying plastic deformation and failure of materials. The data from such tests is used for developing and calibrating material model that are utilized in numerical codes that are used for simulations of practical applications. The presentation will review experimental techniques used in such testing with emphasis on the integration of Digital Image Correlation (DIC) for measuring full-field deformations and the development of new tests. Of special interest is the testing needed for supporting the new deformation and failure model MAT224 in LS-DYNA ® . This material model is based on experimental determination of a failure surface that gives the equivalent plastic strain to failure as a function of stress triaxiality and the Lode parameter. It is done by testing specimens that are subjected to uniform and nonuniform states of stress and deformation and determining the failure state (deformation and stress) from matching the simulation of the test with the DIC and load measurements. Testing can be done at room temperature or, by using a special furnace, at elevated temperatures (up to 850C°). In addition, a new experimental setup in which full-field deformation and full-field temperature are measured simultaneously on the surface of a specimen during a tensile test is introduced. Results from testing specimens made of stainless steel show a significant temperature increase in the neck area in a quasi-static tension test. In most material models (e.g. Johnson Cook) the effect of strain hardening and temperature softening are uncoupled. The data that is typically used for determining the parameters in the models is obtained from experiments where strain hardening and temperature are coupled. The results from the new experimental setup can be used for uncoupling the effect of strain hardening and thermal softening during plastic deformation.

• Materially & Geometrically Nonlinear Woven Composite Micro-mechanical Model with Failure for Finite Element Simulations

  Ala Tabiei, Ivelin Ivanov - University of Cincinnati

  A computational micro-mechanical material model of woven fabric composite material is developed to simulate failure. The material model is based on repeated unit cell approach. The fiber reorientation is accounted for in the effective stiffness calculation. Material non-linearity due to the shear stresses in the impregnated yarns and the matrix material is included in the model. Micro- mechanical failure criteria determine the stiffness degradation for the constituent materials. The developed material model with failure is programmed as user defined subroutine in the LS-DYNA finite element code with explicit time integration. The code is used to simulate the failure behavior of woven composite structures. The results of finite element simulations are compared with available test results. The model shows good agreement with the experimental results and good computational efficiency required for finite element simulations of woven composite structures.

• Mathematical Modeling of Asteroid Falling into the Ocean

  A.V. Abramov, O.V. Voikina, I.V. Minaev -LLC "STRELA" Open Computer Center, V.A. Simonenko - RFNC Zababakhin Research Institute of Technical Physics, E.A. Abramov - South-Ural State University, N.A. Skorkin National Research Nuclear University "MIFI"

  Today, experimental information about large-scale collision tsunami is not available. That is why one of the main tools of studies is mathematical modeling. This paper considers falling of stone asteroid with diameter 1 km into the ocean 4 km deep. This asteroid collides with the Earth at a speed of 22 km/s at angles 30, 60 and 90 degrees. Calculation of space body collision with a barrier is split into two stages. At the first stage, using finite-element code LS- DYNA® [1] and super computer SKIF-URAL of South-Ural State University under the support of OCC “STRELA”, the process of interaction of body with the barrier was calculated. Analysis of calculation data shows that for the angle of incidence 60 and 90 degrees, the results differ slightly. Even for the angle of incidence 30 degrees, we do not have big difference. That is why, one is to expect that the impact of tsunami on the sea shore for these angles of collision will be practically the same. Due to this reason, at the second stage of calculations, we considered the case of axisymmetric penetration of asteroid into the ocean. For describing cylindrically diverging surface wave and its impact on the shore with regard for the shelf profile, a special code was developed, in which approximation of shallow water was realized [3, 4]. It was given empirical formulae for calculation of the height of remote wave that is formed with underwater nuclear explosions [5]. Compared values are in good agreement. This means that using the approach to assessing the parameters of tsunami, which is proposed in this paper, is acceptable both for qualitative and quantitative description of this physical phenomenon. As tentative assessments showed, the aftereffects of the falling of a stone asteroid with diameter ~1 km may be destructive for the ocean shore. Calculations showed that the wave height on the shelf increases from 60 to 100 m. Then the wave height on the shallow water decreases.

• MATHEMATICAL MODELLING OF THE EARLY PHASE DEPLOYMENT OF A PASSENGER AIRBAG – FOLDING USING ORIGAMI THEORY AND INFLATION USING LS-DYNA PARTICLE METHOD

  Krystoffer Mroz, Bengt Pipkorn - Autoliv Development AB, Sweden

  Initial evaluation of the particle method for mathematical out-of-position simulations was performed. The evaluation was carried out by means of static inflation and impactor tests. In the out-of-position load case, the occupant is initially positioned very close to airbag module and the interaction airbag-occupant occurs during the early deployment phase of the airbag. Thus a realistic representation of the folding pattern together with an explicit modelling of the gas flow and the non-uniform pressure distribution play an important role. The first folding step of a 3D passenger airbag concerns the flattening to a 2D shape. The method used in this study was based on mathematical origami theory. The method consists of an initial user specification of one or a few main constraint folds. The remaining creases, which are needed to flatten the 3D airbag to a 2D state with a minimum area loss, were generated using the origami theory. The actual flattening was performed by solving a nonlinear optimization problem. The subsequent folding of the flat 2D airbag into a housing module was carried out by commercially available software. In the mechanical impactor tests, the airbag was inflated with chest and head shaped impactors resting on top of the airbag. The tests were modelled using the particle method for the gas flow and the predictions from the models were compared to the results from the mechanical tests. Good agreement between predictions and test results were obtained. Next step will be to evaluate the method by means of airbag inflation with an occupant positioned close to the airbag.

• Maximizing Cluster Scalability for LS-DYNA

  P. Lui, D. Cho, G. Lotto, G. Shainer (Mellanox Technologies)

  High performance network interconnect is an integral component that enables all compute resources to work together. It is the key to scaling the LS-DYNA simulation in a cluster environment for both network compute and network storage to accelerate CAE simulations. The latest Mellanox InfiniBand adapters have introduced a novel high-performance and scalable architecture for high-performance clusters. This architecture was enhanced to provide higher performance and scalability for the largest supercomputers in the world, today and in the future. In this paper, we demonstrate the new features and technologies that are driven by the latest InfiniBand adapter. Hardware capabilities featuring CPU offloads, MPI tag matching, MPI collective operations acceleration and message transport services make LS-DYNA perform at scale. In this study, we will review the novel architecture used in the HPCX ™ MPI library and explore some of the features in HPC-X that can maximize LS-DYNA performance by exploiting the underlying InfiniBand hardware architecture. The newly debuted Mellanox ConnectX®-5 HCA, which supports up to 100Gb/s EDR InfiniBand will be analyzed as well. For comparison purposes, we will also contrast the performance and scalability advantages of EDR InfiniBand, which is based on an CPU offload architecture, over Intel Omni-Path interconnect, which is based on an onload architecture, on the LS-DYNA simulations.

• Maximizing Cluster Utilization for LS-DYNA® Using 100Gb/s InfiniBand

  Pak Lui, Gilad Shainer, Scot Schultz (Mellanox Technologies, Inc.)

  From concept to engineering and from design to test and manufacturing, the automotive industry relies on powerful virtual development solutions. Crash simulations are performed in an effort to secure quality, safety and accelerate the development process. As the models become more complex to better simulate the physical behavior in crash simulations, the computers that run as a cluster also need to be higher to meet the needs of the higher standards for simulating these more elaborate models. Among the various components in a compute cluster, the high performance network interconnect is an integral factor which is key in making the simulation run efficiently. The Mellanox Connect-IB™ InfiniBand adapter has introduced a novel high-performance and scalable architecture for high-performance clusters. The architecture was designed from the ground up to provide high performance and maximize scalability for the largest supercomputers in the world today and in the future. This paper demonstrates the new features and technologies driven by the Connect-IB InfiniBand adapters. Besides its raw abilities of delivering sub-microsecond latency and a full bandwidth of over 100Gbps using two of the FDR links, its hardware capabilities also includes CPU offloads, MPI collective operations acceleration and message transport services that make LS-DYNA to perform at scale. This paper also demonstrates running multiple parallel simulations to achieve higher cluster productivity, in an effort to exploit with this new level of performance available from the network.

• Maximizing LS-DYNA® Performance and Scalability with In-Network Computing Acceleration Engines

  Ophir Maor, Gerardo Cisneros, David Cho, Yong Qin, Gilad Shainer, HPC Advisory Council

  The Co-Design Collaboration is a collaborative effort among industry leaders, academia and manufacturers, whose mission is to reach the next level of application performance by exploiting system efficiency and optimizing performance. The above is achieved through creating a synergy between the hardware and the software. One of the major outcomes of this collaboration is In-Network Computing technology. This technology enables data algorithms, traditionally managed by the software on general processors, to be managed and executed by the data center interconnect, utilizing dedicated hardware components. This new approach dramatically improves application performance and overall data center return on investment (ROI). In this paper we describe and test the performance of LS-DYNA, benchmarked over the new architecture, and demonstrate its scaling and efficiency capabilities.

• MDO Collision/NV/Stiffness Optimization with LS-OPT

  R. Ishii (JSOL); Y. Tanaka (Toyota Auto Body); M. Nishi (Nihon Emsco); M. Takeda, (JSOL)

  LS-DYNA is heavily used to analysis transient phenomenon like car crash and makes a huge achievement about physical simulation in a wide variety of industry. For the goal of LS-DYNA, gone-model , one-codeh as solution it give you, a wide variety of function has been developed at each section. Nowadays, LS-DYNA has been developed further and become possible to evaluate Frequency domain analysis and Acoustic analysis as FRF/SSD/AcousticBEM/FEM etc. This paper is intended for MDO(Multidisciplinary Design Optimization) with LS-DYNA and LS-OPT. The object is automotive which has many complicated parts. It is so hard to meet the demand for couple of standard for the safety/NV/strength. LS-DYNA can calculate for not only the crash but strength and NV(noise,Vibration) evaluation. The MDO evaluating some linear analyses simultaneously is the common case , but optimization with combination of both linear and non-linear analysis like car crash would be not so common case. It would be possible for LS-DYNA and LS-OPT to consider this case. So, the purpose of this paper is challenge to this case, which mean the confirmation to benefit and effect to car design process. When MDO with collision consideration is regarded useful when car design and estimation of performance , the usage of this type MDO will become widely used.

• Measurement of Electromagnetic Launcher Muzzle Velocity with Induced Voltage of B-Dot Probe

  H.-K. Kim, M.-A. Woo, J. Kim (Pusan National University)

  Recently (early 2013), LS-DYNA has released EM module to solve transient electromagnetic-structural coupled problem. The ‘transient’ means that this software is able to consider shape, deformation and movement of objective model. Until now, there is few commercial software what supports electromagnetic-structural coupled transient problem despite of much necessity. Especially, to facilitate the coupled transient problem, LS-DYNA adopts boundary element method (BEM) what does not need air field mesh manually. By supporting this ability, eddy current, induced heating and resistive heating problems in transient can be successfully and easily solved. In this paper, by using LS-DYNA EM, conduct B-dot probe performance prediction as install positions and directions. Also, measrue muzzle velocity of an electromangetic laucher by the probe.

• Mechanical Characterization of Talc Particle Filled Thermoplastics

  Frank Kunkel, Florian Becker - German Institute for Polymers (DKI), Stefan Kolling - THM

  In this paper, we present the experimental part of the development for an integrative simulation with Moldex3D and LS-DYNA for talc particle lled polypropylene. The properties of thermoplastic polymers considerably depend on the process of moulding irre- spective of the geometry of the part and the raw polymer used. Both, the polymer structure resulting from moulding and formation of weld lines may show a large inuence on mechanical properties. For analysing the inuence of injection moulding on the resulting structural part properties, plates with dierent processing conditions were fabricated with Hostacom XBR169G, a polypropy- lene (PP) lled with rubber and talc. Afterwards, dierent test samples, longitudinal and lateral to ow direction, were milled out from the fabricated plates. Using this extracted test samples, the true deformation and failure behaviour were measured by uniaxial tensile tests and shear tests at small and high strain rates. The complex deformation behaviour was determined by grey-scale correlation strain measurement. The analysis of quasistatic uniaxial tensile tests shows anisotropic eects depending on the prepa- ration direction of the specimen in stress behaviour as well as in Poisson's ratio. This also can be seen at dierent testing temperatures and at high strain rates. The reason of the anisotropic eects might be an orientation of the talc particles. In all experiments, the strain at failure is not inuenced by testing direction. The measured data provide the basis for a material model, which is implemented in LS-DYNA. The model is validated by a three-point bending test.

• Mechanical Modeling of Li-Ion Cell Crush Experiments using LS-DYNA

  M. Seulin, C. Michel, V. Lapoujade (DynaS+);

  Electric vehicles (EVs) and hybrid vehicles (HEVs) sales have grown spectacularly in the last few years. Safety has become an increasingly pressing issue in large-format, energy dense Li-Ion batteries used in electric and hybrid cars. The anticipation of the response to abuse conditions becomes a critical factor in designing optimized systems. Internal short circuit is one of the most dangerous scenario and has been the root cause of several catastrophic accidents in recent years. A 3D electromagnetic (EM) model has been developed in LS-DYNA which, coupled with the mechanical and thermal solvers, allows to simulate battery cells in normal use as well as during abusive scenarios when the structure of the battery is damaged (as a result of a car crash for example). The calibration of the electromagnetic model and the multi-physics coupling first assume the mechanical part of the battery crash to be properly represented. As a consequence, the first step of the corresponding on-going project, presented in this paper, only focus on the mechanical part. Taking into account the very low thicknesses of the different layers, the challenging part and modeling difficulty mainly comes from the computing resources necessary to run the calculation. Thereby it is fundamental to make appropriate and smart modeling choices and use available options in LS-DYNA enabling to reduce the total computational time while ensuring a correct cell behavior. A typical cell unit has been studied both in bending and indentation behaviors so to make appropriate modeling choice (element formulation, aspect ratio…) and then minimize the computation time.

• Mechanical Response Modeling of Different Porous Metal Materials

  Prof. M. Vesenjak, M. Borovinšek, A. Kovačič, M. Ulbin, Z. Ren (University of Maribor)

  Porous metals have been increasingly used in modern engineering applications over the past decades due to their multi-functionality and attractive combination of mechanical and thermal properties [1]. The understanding of their mechanical behaviour is of crucial importance for their use in engineering applications.

• Mesh Sensitivity of Blast Wave Propagation

  David A. Powell, David Bogosian, Baker Engineering and Risk Consultants;, Len Schwer, Schwer Engineering & Consulting Services

  Calculation of blast propagation in air from a high explosive detonation is an often-used feature of LS-DYNA®’s Eulerian capabilities. To obtain credible results, a suitably fine mesh is needed, particularly in the vicinity of the explosive, to represent the nearly instantaneous rise of shock pressure and its gradual decay. In this paper, we aim to present a set of generally applicable guidelines for mesh refinement, using both 2-D axisymmetric and fully 3-D meshes. Models of a Composition B spherical detonation were exercised using various mesh sizes and for charges of varying mass. Simulations made use of the high explosive burn material model and initial detonation card within LS-DYNA. The results were evaluated based on the total impulse at various scaled standoff distances, and then characterized in terms of a scaled mesh dimension (scaled by the cube root of the charge mass). This relationship can be used in future studies to evaluate the trade-off between computational intensity and accuracy of results.

• Meshfree Analysis Using the Generalized Meshfree (GMF) Approximation

  Chung-Kyu Park, Cing-Dao (Steve) Kan - The George Washington University, Cheng-Tang Wu - Livermore Software Technology Corporation

  Meshfree methods are becoming widely used in many industrial fields since the finite element method (FEM) has inherent limitations, such as mesh quality and related distortion problems, to analyze sophisticated problems under large deformation. However, the meshfree methods also have their own deficiencies, mainly the high CPU cost. Recently, the generalized mesh-free (GMF) approximation is developed to improve the efficiency and accuracy in the conventional meshfree methods for solid analysis. The GMF approximation is the integrated formulation to generate existing approximations, such as moving least square (MLS), reproducing kernel (RK), and maximum entropy (ME) approximation, as well as new approximations based on the selection of a basis function. The GMF approximation has two excellent features. The one is that the GMF approximation naturally bears the weak Kronecker-delta property at boundaries, which makes the imposition of essential boundary conditions in meshfree methods easier. The other is that the GMF approximation can be extended to higher-order approximations, which can improve the accuracy of meshfree methods. In this study, some meshfree analyses are performed by LS-DYNA® to demonstrate the performance and accuracy of the GMF approximation. The results show that the convex approximation gives better performance and accuracy than the non-convex approximation in meshfree analysis.

• Meshless Methods in Workbench LS-DYNA

  Ulrich Stelzmann, Yury Novozhilov, Alexander Pett, Erik Plugge

  CADFEM Germany GmbH is working to create an open library of Ansys LS-DYNA [1] industrial use cases. Two new Industrial Use Cases for Ansys LS-DYNA have been developed by CADFEM in 2023. They focus on using meshless methods and the Eulerian approach for real-world applications: SPG usage with GISSMO damage model to simulate material separation and SPH/S-ALE solver usage for inertia-dominated fluid-structure interaction (FSI).

• Meso-Scale FEA modeling to Simulate Crack Initiation and Propagation in Boron Steel

  Yijung Chen, Omar Faruque, Cedric Xia, Alex Akkerman, Dennis Lam (Ford Motor Company)

  The scope of this paper focuses on the characterization and prediction of potential crack initiation and propagation in a boron-steel component under extreme impact load, utilizing a meso-scale FE (0.2 mm solid element) modeling with the MIT MMC (modified Mohr-Coulomb) fracture criterion. The MMC fracture criterion is implemented through LS-DYNA® *MAT224 and *MAT_ADD_EROSION with GISSMO option. A finite element mesh with total number of elements close to 100 million is created to investigate the accuracy of MMC criterion in predicting fracture of a boron component in a dynamic impact test. The CAE results are compared to sled test results for system force-deflection, part deformation mode and crack initiation and propagation.

• Meso-scale Modeling of Carbon Fiber Composites for Crash Simulation

  Dennis Lam, Omar Faruque, James Cheng, Saeed Barbat, Guowei Zhou, Xuming Su, Alex Akkerman, Steve Schaller,, Ford Motor Company, Research and Innovation Center, Dearborn, Michigan

  Typical compression molded laminated carbon fiber composites are made of stacked UD, woven and/or braided carbon fiber pre-pregs oriented differently through the thickness. Resulting micro-structure (layering, anisotropy, inhomogeneity, etc.) is quite complex and greatly affects their mechanical responses. In particular, crash characteristics of CF composites are quite complex and are dominated by both intra-laminar and inter-laminar failure modes such as matrix failure, fiber breakage, fiber buckling, delamination, etc. Despite a large number of constitutive models available in commercial codes, crash simulation of composites is still extremely challenging. This is primarily due to the inadequacy of current macro-scale modeling in characterizing complex micro-structural failure modes during crash.

• Meso-scale modeling of hypervelocity impact on spacecraft foam-core sandwich panels

  A. Cherniaev (University of Windsor)

  In a typical satellite bus, most impact-sensitive equipment is situated in the enclosure of the structural sandwich panels. Being the most commonly used elements of satellite structures, these panels form the satellite’s shape and are primarily designed to resist launching loads and provide attachment points for satellite subsystems [1]. With low additional weight penalties, their intrinsic ballistic performance can often be upgraded to the level required for orbital debris protection [ 2]. Consequently, assessing the orbital debris impact survivability of satellites requires the availability of predictive techniques and hypervelocity impact (HVI) simulation models for sandwich panels, which are capable of accounting for various impact conditions and design parameters.

• Mesomechanical Modeling of the Mechanical Behavior of Parachute Suspension Lines using LS-DYNA®

  Catherine P. Barry, Scott E. Stapleton, David J. Willis, James A. Sherwood (University of Massachusetts Lowell), Francesco Panerai (University of Illinois at Urbana Champaign), Keith Bergeron (U.S. Army Corps of Engineers), Christine Charette, Gregory Noetscher (United States Army Combat Capabilities Development Command-Soldier Center)

  Parachute suspension lines can develop vortex-induced vibrations while in flight, degrading the flight performance and creating noise. To understand the braid design factors associated with this vibration, the mechanical behavior of the braided parachute suspension line can be investigated using a fluid-structure interaction (FSI) analysis. Such an FSI analysis requires a well characterized macroscopic model of the axial, bending and torsional stiffnesses of the line. In the current study, a novel model using a combination of truss elements embedded in solid elements for capturing the asymmetric axial tension-compression stiffness of a tow as well as the lateral compression is presented. Tensile and transverse compression experiments were performed on the individual tows to characterize the axial and transverse stiffnesses to be used with the finite element model. Finite element models of the tow material characterization tests were compared with experimental data to calibrate the material model parameters and to validate the modeling approach. The mesoscale of a suspension line was resolved under zero load using X-ray computed tomography and data were used as the baseline image to generate a finite element model of a representative unit cell of the line. The Virtual Textile Morphology Suite (VTMS) and LS PrePost® were used to obtain the geometry and mesh, respectively. The feasibility to use the novel modeling approach for capturing the mechanical behavior of the braid is demonstrated.

• Message Passing and Advanced Computer Architectures

  Brian Wainscott, Jason Wang - Livermore Software Technology Corporation

  The emergence of distributed memory and cluster based computers is a recognized trend, with obvious cost/performance benefits. Here we discuss strategies for efficient utilization of these architectures on industrial problems. Results are presented which investigate the communication bandwidth and latency requirements for production environments.

• Meta-Model Based Optimization of Spot-welded Crash Box using Differential Evolution Algorithm

  A. Serdar Önal, Beyçelik Gestamp Kalip ve Oto Yan San. Paz ve Tic.), N. Kaya (Uludağ University)

• Metal Forming Applications using Implicit Mechanics Features of LS-DYNA

  Roger G. Grimes, Xinhai Zhu - Livermore Software Technology Corporation

  The authors will present the use of LS-DYNA for a variety of metal forming applications. They will present some new features and improvements in Version 971 of LS-DYNA such as Inertia Relief and Contact Penetration Detection. The presentation will include applications of gravity loading, binder wrap, flanging, springback and die transfer.

• Metal Forming Automation using LS-OPT ®

  Krishna Chaitanya Kusupudi (Whirlpool Corporation)

  The principal objective of this paper is to demonstrate the Metal Forming automation setup using LS-OPT, in which CREO (CAD software), Hypermesh (FE pre-processor), LS-DYNA ® (FE Solver) and LS-PrePost ® (FE post- processor) are integrated. Metal Forming simulations are performed to check the formability of an intended geometry for various process settings like different draw bead retention forces, friction coefficient, blank dimensions, material properties, etc. In case of formability issues, geometry modifications are implemented in the necessary areas. Automation in any process will help to reduce the manual effort in running various combinations, saves time and gives more accurate results. Automation workflow is developed with reference to general metal forming simulation approach. To modify the geometries at concerned areas, CAD software is required. FE –preprocessor is required to create new mesh for modified geometry. LS-DYNA and LS-PrePost is used for solving and post processing respectively. In this work, Design of experiments (DOE) are performed to understand the effects of process parameters and critical dimensions of geometry on formability (Maximum thickness reduction, Crack elements, Risk of Crack elements, Wrinkles, etc). Critical process parameters and affecting areas in the geometry are indentified. Affecting areas are made parametric and significant process parameters which have significant effect on formability are considered. From data analysis of DOE results, a relation can be obtained between geometric dimensions, process parameters and formability responses. The knowledge obtained is shared with Design team and Tool makers. The Automation setup will be used for Optimization, Monte Carlo simulations, etc based on the requirement.

• Metamodel Sensitivity to Sampling Strategies: A Crashworthiness Design Study

  Nielen Stander, Tushar Goel - Livermore Software Technology Corporation

  A study is conducted to determine the sensitivity of 2 topologically distinct metamodel types to variations in the experimental design brought about by sequential adaptive sampling strategies. The study focuses on examples encountered in crashworthiness design. Three sampling strategies are considered for updating the experimental designs, namely (i) a single stage approach, (ii) a sequential approach and (iii) a sequential approach, but with higher densities in local regions. The experimental design type is the Space Filling Method based on maximizing the minimum distance between any two design points within a subdomain. Feedforward Neural Networks (NN) and Radial Basis Function Networks (RBF) are compared with respect to their sensitivity when applied to these strategies. A large set of independent checkpoints, constructed using a Latin Hypercube Sampling method is used to evaluate the accuracy of the various strategies. Four examples are used in the evaluation, namely (i) simple two- variable two-bar truss, (ii) the 21 variable Svanberg problem, (iii) a 7 variable full vehicle crash example and (iv) a 11 variable knee impact crash example. The example, analyzed using LS-OPT® for metamodeling and LS-DYNA® for FE modeling, reveal the following: while expensive to construct, NN committees tend to be superior in predictability whereas the much cheaper RBF networks, can sometimes be highly sensitive to irregularity of experimental designs caused by subdomain updating. However, this conclusion cannot be extended to the crash problems tested, since the RBF networks performed consistently well for these examples.

• Methodologies and Examples for Efficient Short and Long Duration Integrated Occupant-Vehicle Crash Simulation

  R. Reichert, C.-D. Kan, D. Marzougui, U. Mahadevaiah, R. Morgan, C.-K. Park, F. Tahan (George Mason University)

  Integrated occupant-vehicle analysis plays an important role in vehicle and occupant safety developments. Car manufacturers are using detailed full system models consisting of vehicle structure, interior, restraint systems, barrier, and occupant to develop safety measures and assure compliance with legal requirements, good rating results in consumer information tests, and vehicle safety in real life crash configurations. Suppliers are using sub-system models to design and optimize interior and restraint system components with respect to various component and system requirements. This paper describes efficient methodologies for fully integrated occupant-vehicle simulations as well as sub-system evaluations using prescribed motion in LS-DYNA®. Examples include different short duration impacts such as frontal and side impact configurations with termination times of less than 200 milliseconds, and long duration impacts such as rollover events with termination times of 400 to 2500 milliseconds. A frontal offset and a frontal oblique impact was simulated using a Toyota Yaris model, side impact simulations were conducted with a Ford Taurus model, and a Ford Explorer model was used for rollover evaluations. Occupant models used include a Hybrid III, a THOR (Test device for Human Occupant Restraint), a US side impact, and a WorldSID dummy, as well as a THUMS (Total HUman Model for Safety) human model. Simulation results are compared to available full-scale crash test data. Parametric studies have been conducted to examine the influence of different input and output parameters when using sub-models with prescribed motion.

• Methodology for Selection of Material Models for Plastics Impact Simulation

  Hubert Lobo - DatapointLabs

  The volume of plastics that are subjected to impact simulation has grown rapidly. In a previous paper, we discussed why different material models are needed to describe the highly varied behavior exhibited by these materials. In this paper, we cover the subject in more detail, exploring in depth, the nuances of commonly used LS-DYNA material models for plastics, covering important exceptions and criteria related to their use.

• Methods for Modeling Solid Sports Ball Impacts

  Derek Nevins, Lloyd Smith (Washington State University)

  Finite element modeling of dynamic sports ball impacts presents a substantial challenge. This is because, rather than displaying linear-elastic behavior, many sports balls are predominantly non-linear, inelastic and rate dependent. This is true of both softballs and baseballs, which exhibit strong rate-dependence and large energy dissipation characteristics in collisions occurring under play-like conditions. The development of finite element models of these balls is further complicated by the difficulty in measuring materials properties at strain rates and magnitudes representative of play. This work describes the development of novel ball models from data obtained under play-like conditions. Ball models were implemented in LS-DYNA® using the Low-Density Foam material model. Simulations were compared to empirical data collected over a range of ball speeds. Models displayed good agreement with experimental measures of energy dissipation and impact force and represent an improvement over commonly used viscoelastic models.

• Micro-Meso Draping Modeling of Non-Crimp Fabrics

  O. Vorobiov, T. Bischoff, A. Tulke (FTA Forschungsgesellschaft für Textiltechnik Albstadt)

  Composite materials with textile reinforcements are showing rapid growth of integration in aerospace, automotive, sport and other industrial sectors. Especially non-crimp fabrics (NCF) are widely spread because of their high drapeability and good in-plane mechanical properties in main fibre directions. For prediction of mechanical response of composite parts in particular with high curvature it is important to consider the local orientations and gaps in textile structures obtained after draping. Draping simulations are performed on meso-scale structure for this reason.

• Micromechanics analysis applied to the modelling of aluminium honeycomb and EPS foam composites

  Gaetano Caserta, Lorenzo Iannucci - Imperial College London, Ugo Galvanetto - Padova University

  A 3D Finite Element model of an innovative composite material, configured as a layer of expanded aluminium honeycomb placed on top of a layer of expanded polystyrene foam, has been developed and validated against experimental data obtained from quasi-static tests. Ls-Prepost was used to generate the model. Ls-Dyna was used to simulate the behaviour of this material under compressive loads. The objective was to reproduce deformation mechanisms and to compare the numerical load-displacement curves with those obtained from experiments. The loading direction was chosen perpendicular to the plane of the alignment of the honeycomb cell walls. Particular emphasis was given to the contact between the aluminium honeycomb cell walls and the surface of the foam. Because of the periodicity of the geometrical and material properties, these composites were modelled as a unit cell according to the principles of the micromechanics analysis of periodic structures. In addition, to further reduce computational costs, the inner symmetries of the unit cell were exploited to generate and validate a smaller unit cell model (here called sub-cell). The results obtained from analysis of both the unit cell and the sub-cell were compared with experimental data. Numerical results showed good accuracy even when the smaller unit cell was used.

• Micromechanics analysis applied to the modelling of aluminium honeycomb and EPS foam composites

  Gaetano Caserta, Lorenzo Iannucci - Imperial College London, Ugo Galvanetto - Padova University

  A 3D Finite Element model of an innovative composite material, configured as a layer of expanded aluminium honeycomb placed on top of a layer of expanded polystyrene foam, has been developed and validated against experimental data obtained from quasi-static tests. Ls-Prepost was used to generate the model. Ls-Dyna was used to simulate the behaviour of this material under compressive loads. The objective was to reproduce deformation mechanisms and to compare the numerical load-displacement curves with those obtained from experiments. The loading direction was chosen perpendicular to the plane of the alignment of the honeycomb cell walls. Particular emphasis was given to the contact between the aluminium honeycomb cell walls and the surface of the foam. Because of the periodicity of the geometrical and material properties, these composites were modelled as a unit cell according to the principles of the micromechanics analysis of periodic structures. In addition, to further reduce computational costs, the inner symmetries of the unit cell were exploited to generate and validate a smaller unit cell model (here called sub-cell). The results obtained from analysis of both the unit cell and the sub-cell were compared with experimental data. Numerical results showed good accuracy even when the smaller unit cell was used.

• Micromechanics Based Composite Material Model for Impact and Crashworthiness Explicit Finite Element Simulation

  Ala Tabiei, Quing Chen - University of Cincinnati

  A micro-mechanical model is developed for laminated composite materials and implemented in the explicit finite element method. The objective of this study is to get an accurate and simple micro-model, which can be used in the displacement-based nonlinear explicit finite element code DYNA3D. The micro-mechanical model implemented in the explicit finite element code can be used for simulating the behavior of composite structures under various loads such as impact and crash. The stress-strain relation for the micro-model is derived for shell element. Micro Failure Criterion (MFC) is presented for each material constituent and failure mode. The implemented model is validated through several test examples. As a demonstration case of the stability of the developed micro-model a finite element model of Graphite/Epoxy tube structure is developed and simulated under axial crash.

• MICROSTRUCTURE EVOLUTION AND MECHANICAL RESPONSE IN THE HOT STAMPING PROCESS

  Mats Oldenburg, Per Salomonsson - Luleå University of Technology, Paul Åkerström, Greger Bergman - Gestamp Hardtech AB

  In the manufacturing of ultra high strength boron steel components with the hot stamping process, it is of great importance that the final product will have the desired material properties. This is especially true for safety related automotive components. Often the preferred microstructure is a mix of martensite and bainite. In this work a model is developed and implemented in order to predict the austenite decomposition into ferrite, pearlite, bainite and martensite during arbitrary cooling paths. The model is based on Kirkaldy’s rate equations and later modifications by Li et al. After modification, the model accounts for the effect from the added boron and the effect of straining at high temperatures. The implementation is as part of a material subroutine in the finite element program LS-Dyna. The achieved volume fractions of microconstituents and hardness profiles in the analyses show good agreement with the corresponding experimental observations. The phase content affect both the thermal and the mechanical properties during the process of continuous cooling and deformation of the material. A thermo-elastic-plastic constitutive model including effects from changes in the microstructure as well as transformation plasticity is implemented in the LS-Dyna code. The model is used together with a thermal shell formulation with quadratic temperature interpolation in the thickness direction. The developed methods are used to simulate the complete process of simultaneous forming and quenching of sheet metal components. The implemented models are used in coupled thermo-mechanical analysis of the hot stamping process and are evaluated by comparing the results from hot stamping experiments. The results from simulations such as local thickness variations, hardness distribution and spring-back in the component show good agreement with experimental results. However, it is shown that the simulation of the final cooling stage relies on a correct modelling of contact properties and heat transfer.

• Mild Traumatic Brain Injury-Mitigating Football Helmet Design Evaluation

  M.S. Hamid (Advanced Computational Systems, LLC), Minoo Shah (IDIADA Automotive Technology)

  Concussion, as known as mild Traumatic Brain Injury (mTBI), is the most common sport-related head injury. Football is the most common sport with higher concussions in USA. Helmet is the equipment being used in mitigation of mTBI. There are numerous designs of helmets which meet the requirements of sport regulation committee. In this paper, a football helmet is evaluated using numerical methods. The brain and the tissues in human head are modelled using continuum Smoothed Particle Hydrodynamics (SPH). The brain tissues are generated by segmentation from human brain MRI data. The LSTC dummy is used to represent the football players. The brain tissue is fitted in the cavity of the dummy headform. Two different impact scenarios are simulated in this study. The results for these impact conditions are presented.

• Mitigating Risks at Bus Stops: A Study of the Effectiveness of Bollard Systems

  Jonathan Lazatin, Pouya Shojaei, Brendan O’Toole, Mohamed Trabia

  This work assesses the effectiveness of a proposed interconnected multi-bollard design in protecting bus stop occupants from incoming vehicles. A detailed model of a 3-bollard system was developed in ANSYS LS-Dyna®, which included the bollards, their underground support structures, and the rebars connecting the bollards. The bollard system was composed of 116 parts with a total of 443,799 elements. The system model was merged with a detailed model of a 2007 Chevrolet Silverado, 4-door crew cab pickup truck with 603 parts with 251,400 elements developed by the Center for Collision Safety and Analysis [1]. The vehicle was simulated to impact the bollard system at speeds between 15 and 90 mph at angles ranging from 0° (normal to the bollard system) and 90° (parallel to the bollard system). Impacts were also made at various degrees of centeredness, with cases showing response from impact at the center of bumper, as well as at the edge of the bumper. With each case, vehicle velocity and acceleration were monitored using virtual accelerometers, placed in the vehicle to assess the effectiveness of the bollard to stop the vehicle. Simulation results show that the bollard was able to stop a vehicle traveling normal to the bollard system, impacting the center of the bumper at speeds up to 45 mph. However, the vehicle would continue past the bollard system at higher speeds.

• Mixed Mode Constitutive Driver

  Yvonne D. Murray, Carolyn M. Yeager - Aptek, Inc.

  The mixed-mode constitutive driver is a software package that is dedicated to the efficient development, evaluation, and parameter identification (fitting) of material models used in finite element codes. The core driver calculates the stress-strain behavior of material models driven by combinations of strain increments and stress boundary conditions. Graphical user interfaces facilitate selection of the material model constants and desired load histories, and plot model output in two (stress-strain curves compared with test data) and three (yield surfaces) dimensions. Optimization routines fit the material models to test data. Optimization is accomplished by interfacing the driver with the LS-OPT code. The driver complements the performance of finite element codes. Its intended use is to help analysts efficiently fit and evaluate material models, with consistent results, prior to performing large-scale finite element analyses.

• MLS-based SPH in LS-DYNA® for Increased Accuracy and Tensile Stability

  Edouard Yreux, Livermore Software Technology Corporation

  Two important limitations of the Smoothed Particle Hydrodynamics are low accuracy and tensile instability. While the former can be somewhat alleviated by employing very fine discretizations and renormalized formulations, the latter can only be slightly mitigated with heavy use of artificial viscosity. In addition, renormalized formulations can be unsuitable for extreme deformations and impact simulations, and excessive artificial viscosity can severely alter the physics of the problem being modeled. A new formulation based on a Moving Least-Squares approximation and an improved nodal integration scheme is presented in this paper. The method is shown to be much more stable in tension, and very accurate. Extensive comparisons with traditional SPH and with experimental data are presented.

• MME-Converter and MME-Report for LS-DYNA® Users

  Seung Hun Jeong (10DR KOREA Co., Ltd.)

  This paper will focus on the main features, benefits and use of MME-Converter and MME-Report which could be highly useful to LS-DYNA users for vehicle crash test analysis. With MME-Converter users can simply convert LS-DYNA result files, such as nodout, elout, deforc and rcforc to MME-filtered files through the auto-syntax analysis and then compare these converted MME-filtered files to real vehicle crash test data. The conversion of LS-DYNA files is carried out in accordance with the international occupant protection criteria including KNCAP, USNCAP, Euro NCAP and IIHS. Furthermore, MME-Report which is one-page reporting system using MME-filtered data helps users to create concise, professional engineering reports, so that engineers in CAE teams, could share the test results with each other and even use them for formal meetings or presentations.

• Modal Dynamics in LS-DYNA®

  Roger Grimes (LSTC)

  In LS971 R71, LSTC has enhanced its capabilities in Modal Dynamics from previous versions. This talk will give an overview of the enhanced capabilities which include mode selection and modal damping. We will present an industrial example of using this capability including a comparison of using Modal Dynamics and a full simulation.

• MODAL METHODS FOR TRANSIENT DYNAMIC ANALYSIS IN LS-DYNA

  Bradley N. Maker, David J. Benson - Livermore Software Technology Corporation

  Modal analysis methods offer an opportunity for tremendous cost savings compared to traditional explicit approaches to transient dynamic analysis. Modal methods approximate the structural response of a body by a linear combination of pre-computed mode shapes, eliminating the need for explicit element processing. LS-DYNA’s new modal analysis capability is combined with existing rigid body features to offer the additional advantage of large rigid body motion with superimposed linear modal response. This allows a portion of an LS-DYNA model to be represented by modes, while other parts of the model are treated with standard nonlinear explicit methods. LS- DYNA has also been enhanced to compute several types of modes, including eigen modes, constraint modes, and attachment modes. These modes are written to binary databases which can be viewed using LS-POST, and used as input to subsequent modal analyses. This paper introduces these new features for modal analysis, focusing on modeling procedures, input parameters, and examples of potential cost savings.

• Modal Properties of Turbo-Compressor Elements

  V. Ignatkov, S. Klambozki, S. Medvedev, M. Petrushina - UIIP NAS of Belarus

  In this paper some modal and vibration properties of turbocompressor elements are studied. Natural frequencies of turbokompressor rotor shaft with turbine and compressor wheels and bearing unit elements are calculated. Their spectrum dependence on the material properties of the elements and on the constructive variants of the bearing unit components are studied. Shape modes of the system are obtained . The vibrations of the system at the maximal angular velocity are estimated. The oscillations of the turbine and compressor blades are found for that angular velocity . The natural frequencies and shape modes of the separate blades of the turbine and compressor are found. The blades response to short pressure pulses are studied. The conditions of resonance are investigated.

• Mode-based Frequency Response Function and Steady State Dynamics in LS-DYNA

  Yun Huang - Livermore Software Technology Corporation, Bor-Tsuen Wang - National Pingtung University of Science and Technology

  Two new features used for frequency domain structural analysis --- frequency response function (FRF) and steady state dynamics (SSD), have been implemented in LS-DYNA, based on mode superposition techniques. As a characteristic of a structure, FRF is the transfer function which represents structural response resulting from applied unit harmonic excitations. The harmonic excitations can be given in the form of nodal force, base acceleration or pressure. The FRF feature provides user the opportunity to acquire a spectrum of structural response (displacement, velocity and acceleration) for the applied unit excitation. As a direct extension of FRF, SSD calculates the steady state dynamic response of a system subjected to a given spectrum of harmonic excitations. Both FRF and SSD give results in complex variable form, enabling user to obtain not only amplitude of response, but also phase angle. A benchmark example of a rectangular plate is included to demonstrate the effectiveness of both features. Some discussions regarding the effect of damping and individual mode contributions are also included.

• Model Based Design of Pressure Profiles for Pyrotechnic Actuator using SPH Method & LS-OPT Solution

  E. Kantor, Y. Lev (Rafael)

  Pyrotechnic Pistons are communally used as fast reacting actuators in many elds and applications, such as seat belt pretensioners, wire and cable cutters and power disconnect devices. The design of such devices is subjected to many unknowns and the design methodology sometimes consists of many experiments in a trial & error methodology. This paper presents the design process of such a device. In this work a MBD process was applied using LsDyna® model and LsOpt® optimized solution for reaching upper and lower bounds for the pressure proles of a pyrotechnic device. The numerical solution decreases the number of required experiments in the design process and cuts its costs.

• Model improvement during seat project

  Christofer Karlsson, Scania CV AB

  To help predict the behaviour of a seat assembly when performing a seat belt anchorage pull test (according to regulation ECE R14/05 and directive 76/115/EEC) a FE-model has been built and improved in several steps. To increase the accuracy of the simulation (quasi static), a number of modifications were made to the initial model. The adjustments include higher mesh density, allowing a better representation of the geometry. A tensile strength test has been performed on one critical component which showed a lower yield strength than that provided by the supplier which called for a model update. Physical tests have been carried out and simulation results have been compared to these tests. While doing so, the rails at which the seat is mounted on and the lock sleeves that keep the rails in its position were considered to be too week in the model. By incorporating thick shell elements, this issue was solved. It is believed that these combined modifications significantly improve the performance of simulating a pull test.

• Model Reduction Techniques for LS-DYNA ALE and Crash Applications

  K. Kayvantash, A.-T. Thiam (CADLM), S. B. Chaabane, J. Touzeau (Silkan)

  Model Reduction Techniques (MRT) are algebraic approximation solutions allowing for fast (real- time) interpolations (reconstruction) or extrapolations (prediction), based on previously existing DOE-type results, obtained either from FE computations or directly from constructions of reduced FE solutions. In a sense reduced models are subsets or decomposed domains of the solutions allowing for reconstruction of all spatial or temporal domain response. Contrary to FE where global interpolations are based on local "shape" (geometrical) functions, reduced models are based on basis functions which include not only geometrical but also material, boundary conditions and loading. This contributes greatly to fast solver solutions for on-board computing and may be used for time dependent approximations.

• Model Set up and Analysis tools for Squeak and Rattle in LS-DYNA ®

  Thanassis Fokilidis (BETA CAE Systems SA), Jens Weber, Mehrdad Moridnejad (Volvo Cars)

  One of the most important quality aspects during the design process of a vehicle is the provided occupant comfort. Comfort in a vehicle is achieved, among others, through a quiet and durable interior, and through the elimination of Squeak and Rattle noises. A huge amount of different tests take place in laboratories in order to produce interior and exterior components that eliminate the occurrence of such undesirable phenomena. As a result, developing numerical models that explain and predict the behavior of a vehicle in Squeak and Rattle is important. The implementation of automated tools benefits analysts in setting up efficient and robust processes for accurate and straightforward CAE simulations. A simulation method that is used for the Squeak and Rattle numerical analysis is the E-LINE method which focuses on calculating and evaluating the relative displacement between two components in the time domain. Based on this method BETA CAE Systems in cooperation with Volvo Cars has developed a set of special tools in ANSA pre-processor and μETA post-processor for identifying the crucial areas, setting up the LS-DYNA E-LINE model definitions for them, and finally evaluating the corresponding LS-DYNA implicit results. The current paper dives deep in E-LINE method by showing both interior and exterior examples. In addition, it presents the BETA CAE Systems automated tools that offer a complete and effective solution in Squeak and Rattle analysis using LS-DYNA, minimizing simulation time consumption and human interaction.

• Model Set up, Analysis and Results of the Inverse Forming Tool in ANSA

  Evlalia Iordanidou, Georgios Mokios, BETA CAE Systems SA

  With an ongoing aim to reduce the time a model requires to be prepared, the sheet metal forming studies have evolved to catch up. This affects initially the die designers, who are requested to decide the manufacturing processes early in the design process as well as process engineers who aim to incorporate stamping results in further studies. Feasibility analyses are one kind of such studies, performed to check whether a part can be created from a forming procedure. The blank shape is estimated and cost is estimated too. Through such an analysis, the results of thinning and work hardening are produced and are used in further structural studies.

• Modeling Adhesively Bonded Joints with *MAT252 and *MAT_ADD_COHESIVE for Practical Applications

  F. Burbulla (Dr. Ing. h.c. F. Porsche), A. Matzenmiller, U. Kroll (University of Kassel)

  The new material model *MAT_TOUGHENED_ADHESIVE_POLYMER ( *MAT_252 ) has been developed at the Institute of Mechanics of the University of Kassel [1], [2] and become available for the use with solid elements since LS-DYNA R7.1.1 . The theoretical framework of the model equations is based on continuum and damage mechanics in order to predict the complex mechanical behaviour of crash optimized high-strength adhesives under combined shear and tensile loading.

• Modeling Aluminum Honeycomb Under High Velocity Impact

  Murat KAMBEROGLU

  Aluminum Honeycombs are classified as advanced engineering solution for specific requirements and utilized as composite core material, thermal isolator, optical aligner, floor mat, packaging filler and energy absorber for different industries. Many materials may be mentioned here as cheaper and simpler alternative that can offer similar or maybe higher performance for these purposes even with lower cost, however none of them can come close to the weight advantage of honeycombs thanks to the extensive air space and load path provided by its peculiar shape.

• Modeling and Simulation of the long-term Behavior of Thermoplastics in LS-DYNA

  M. Morak (Polymer Competence Center Leoben), R. Steinberger, I. Sladan, S. Seichter (Hirtenberger), W. Hahn, M. Göttlinger (Hilti), P. Reithofer, M. Schwab, H. Pothukuchi (4a engineering)

  Viscoelasticity respectively the time-dependent and the recovery behavior plays an essential role, especially for polymers. Nowadays, it is becoming increasingly important to be able to make service life predictions and forecasts regarding the long-term behavior of components using simulation models. In this context, constant or cyclic loads are usually the decisive mechanisms for deformation. Moreover, the short-term behavior of plastics is also strongly characterized by viscoelastic phenomena. Even in the case of very short-time high loads on polymer components, the corresponding recovery behavior is of great importance and must be correctly represented in the simulation. Material and simulation models must take this long-term but also the short-term behavior into account for a realistic prediction of the deformation behavior in order to be able to make corresponding estimates of the service life of components, which is often designed for years. For this purpose, this behavior must be characterized in the application-specific framework and considered accordingly in the modeling. This article will present and compare some of the currently available material models that can account for the viscoelastic or time-dependent behavior of polymers, as well as the possibilities and effort required to obtain the material data needed for simulation.

• Modeling and Simulation of Bogie Impacts on Concrete Bridge Rails using LS-DYNA

  Akram Abu-Odeh - Texas Transportation Institute

  Bridge rails are constructed to contain and redirect an errant vehicle. They are constructed to withstand the impact severity of such vehicular impact based on the desired containment level. To evaluate the structural integrity of a given bridge rail design, bogie tests were conducted using a 5000 lb bogie as an impactor. In this paper, LS-DYNA was used to model the concrete barrier to simulate the bogie impact. Three material models in LS-DYNA (type 72R3, 84 and 159) were used to simulate the impact event. The rebars to concrete coupling was modeling via the *CONSTRAINED_LAGRANGE_IN_SOLID feature in LS-DYNA. Time history and deformation profile comparisons between tests and LS-DYNA simulations are presented in this paper. Figure 1 below shows a damage profile for the barrier as tested and as simulated in LS-DYNA.

• Modeling and Simulation of PCB Cover Plate for Large Open Joints

  Sagheer A. Ranjha, Robert W. Bielenberg, Ronald Faller, Scott Rosenbaugh, John D. Reid, Cody Stolle, Midwest Roadside Safety Facility Mechanical and Materials Engineering University of Nebraska-Lincoln

  An improved LS-DYNA® model of steel cover plate for accommodating variable gaps in roadside portable concrete barrier (PCB) installations has been developed. A two-piece cover plate model was evaluated using non-linear finite element analysis program LS-DYNA. Baseline model of F-shape PCB validated with full-scale crash testing is presented. Baseline modeling and simulation details are discussed, including the range of numerical problems and vehicle and evaluation parameters. Cover plates across the barrier joint were added using fully-integrated shell elements along with piecewise-linear plasticity material. Cover plate model was sufficiently calibrated with baseline model in order to evaluate the gap spanning hardware design. Computer simulations were conducted with a Chevrolet Silverado Version 2 (V2) model pickup truck impacting the PCB cover plate installation. Results show that cap thicknesses of less than 6 mm resulted in unacceptable buckling of cover plate. Good performance was obtained with a 6-mm thick cover plate with modified base plate and incremental stiffeners. Additional simulations and full-scale crash testing is required before guidelines can be recommended.

• Modeling and Simulation of Bridge - Track - Train Systems at High Service Velocities with LS-DYNA

  M. Klasztorny, P. Szurgott (Military University of Technology, Department of Mechanics and Applied Computer Science)

  The paper develops a new methodology of FE modeling and simulation of the bridge – track – train systems at high service velocities with the use of selected CAE systems. The methodology is presented on the KNI 140070 viaduct with composite (steel – concrete) superstructure and 14.40 m span length, located on the Central Main Line, Poland. A ballasted track and two types of high speed trains have been modeled physically and numerically. The study includes German ICE-3 (InterCityExpress) train with classic bogies and Korean KTX (Korea Train eXpress close to French TGV) train with classic and Jacobs bogies. A methodology of the FE modeling and simulation of the bridge – track – moving train system is based on the following concept. The physical and numerical modeling of the viaduct – track – train system was performed with Altair HyperMesh® and LS-PrePost® software. The FE model of the bridge superstructure consisted of 4-node shell elements (main beams) and 8-node 48 DOF solid elements (RC platform). In order to simulate the moving train – track interaction, RAIL_TRACK and RAIL_TRAIN modules available in LS-DYNA system were used. Hughes-Liu beam elements were used for rail modeling whereas rail fastenings were simulated using one-dimensional discrete spring and damper elements. Carbodies, bogie frames and wheelsets were considered as rigid bodies and they were modeled using shell and beam elements. Cylindrical and revolute constrained joints and discrete springs and dampers were applied to connect components of the FE model of rail-vehicles. In the longitudinal direction, the FE mesh of the system is based on a 600 mm length module. DYNAMIC_RELAXATION is omitted via applying the static wheel loads increasing in the cosine shape in the 2-sec initial time interval. The quasi steady-state wave in the track is generated after the initial time interval. Dynamic response of the bridge – track – train system is registered in the form of displacement and acceleration time- histories at the design cross-sections as well as displacement and stress contours in reference to main steel beams.

• Modeling and Simulations of Vehicular Impacts on W-Beam Rail with Raised Blockouts

  C. Silvestri Dobrovolny, N. Schulz, R.P. Bligh (Texas A&M Transportation Institute), C. Lindsey (Texas Department of Transportation)

  With recent changes about appropriate height for beam guardrail, there are more locations where rail height is below the recommended heights. Raising blockout on posts is a cost effective means to adjust rail height, however there is not any known analysis of how this might affects rail performance. The information compiled from this simulation study will enable the DOTs to decide whether raising wood blockouts on wood posts can be chosen as a cost effective mean to adjust rail height when below recommended value, without compromising the rail system performance. Researchers made use of pendulum testing facility to test raised 8-inch wood blockouts on wood posts embedded in soil. Force-displacement data was recorded and evaluated to understand the strength of raised blockout on wood post system and its capability to transmit impact forces into the soil. Results from pendulum testing were also employed to calibrate the behavior of a finite element model of a post and raised blockout system embedded in soil. The researchers detected real-world configurations of W-beam guardrail installations with wood blockouts on wood posts and identified those configurations for which the practice of raising wood blockouts on wood posts would need some additional investigation to assess system crashworthiness according to roadside safety standards. Three cases were identified for further evaluation through FEA analyses: 1) 31-inch MGS system, 4-inch pavement overlay in front of post and 4-inch raised blockouts on posts; 2) 273⁄4-inch rail system, 4-inch increased post embedment due to possible rail deficiency or posts settlement, and 4-inch raised blockouts on posts; 3) 273⁄4-inch rail system, 4-inch pavement overlay in front of post and 4-inch raised blockouts on posts. All cases indicate that the practice of raising wood blockouts on wood posts to maintain minimum rail height requirements appear to likely pass required roadside safety evaluation criteria.

• Modeling and Validation of Static and Dynamic Seat Cushion Characteristics

  D. V. Dorugade (Concordia University), P.-E. Boileau (McGill University)

  Automotive seat cushions contribute considerably to static and dynamic comfort of the drivers. Design of a cushion is highly challenging due to its highly nonlinear viscoelastic behavior that is dependent on the seated body mass, and magnitude and rate of the vibration excitation. In this study, a dynamic seat cushion model is developed in the LS DYNA platform to determine its static and dynamic properties. The material model *MAT_FU_CHANG_FOAM_DAMAGE_DECAY (083_1) was used, which showed capability to predict nonlinear dynamic cushion behavior under different preloads, and excitation frequencies and amplitudes. This material model, available in the LS DYNA library, permitted evaluations of the nonlinear rate-dependent viscoelastic behavior of the cushion. The effectiveness of the model in predicting static and dynamic responses is demonstrated by comparing the simulation results with the laboratory-measured data in terms of force-deflection characteristics. The comparisons revealed reasonably good agreements between the simulation and measured responses. Contact pressure distribution on the seat cushion was further obtained, which also showed good qualitative agreement with the reported measured data.

• Modeling and Validation of Failure Behaviors of Composite Laminate Components using MAT_262 and User Defined Cohesive Model

  Masato Nishi1, Masato Iimori, Kei Saito (JSOL Corporation), Tsuyoshi Nishihara, Chikara Kawamura, Shunsuke Kanemoto, (Mazda Motor Corporation), Stefan Hartmann (DYNAmore Corporation)

  The objective of the present study is to develop a finite element (FE) approach to predict the changes in failure behavior of a unidirectional carbon fiber reinforced plastic (CFRP) material for different laminate configurations in LS-DYNA®. Damage related parameters for an intra-lamina material model are often adjusted by reverse engineering. However, in our study, we identified these parameters in material type 262 based on a crack resistance curve, which shows the relationship between fracture toughness and crack length. A user defined cohesive zone model was also developed to take into account anisotropic inter-laminar fracture toughness depending on the fiber orientation. The changes in fracture behavior observed in the different laminate configurations in experiments can be represented in four-point bending simulations of a CFRP laminated component using the developed FE model.

• Modeling Bird Impact on a Rotating Fan: The Influence of Bird Parameters

  M. Selezneva, K. Behdinan, C. Poon - Ryerson University, P. Stone, T. Moffat - Pratt and Whitney Canada

  The ability to withstand bird impact is one of the major requirements of the modern aircraft jet engine. In fact, rigorous certification procedures are put in place to assess the engine’s ability to sustain severe impact loads developed during bird impact. Full scale bird tests are expensive and time consuming, and call for the use of accurate numerical approximations during the design stages of engine development. The main difficulties encountered in achieving accurate finite element (FE) analysis are related to modeling of the bird which undergoes severe deformations, and modeling of the contact between the bird (soft) and blade (stiff) materials. Thus far Smooth Particle Hydrodynamics (SPH) modeling in LS-DYNA®, which is a meshless method, had shown potential in adequately modeling the bird and the bird-blade interactions. Recent publications also show the ability of SPH based models to capture impact strains and forces seen by the rotating fan blades [1, 2]. The current study further investigates the interaction of the SPH bird with the FE blades, and the ability of the model to capture realistic blade deformation. The main emphasis is placed on the effect of the bird related parameters on the damage sustained by the blades.

• Modeling Blast Damage of Composite Structures

  Bazle A. Gama, Venkat S. Chiravuri, and John W. Gillespie Jr. - University of Delaware

  Blast loading on monolithic materials, sandwich structures, and composite flat plates and cylinders are investigated using LS-DYNA blast loading function and the progressive composite damage model MAT162. Energy dissipating damage mechanisms, momentum transfer, resistance forces, accelerations, and dynamic displacements are analyzed to understand the blast resistance behavior of the flat plates and the cylinders.

• Modeling Bolts in LS-DYNA© Using Explicit and Implicit Time Integration

  Nils Karajan, Alexander Gromer, DYNAmore Corporation;, Thomas Borrvall, DYNAmore Nordic;, Kishore Pydimarry, Honda R&D Americas, Inc.

  When setting up models for analysis using the explicit solver in LS-DYNA, the method of how to model bolted connections is usually well known. However, when this model or even just certain substructures of the model are used for load cases to be solved using the implicit solver in LS-DYNA, problems might arise that you might have not been aware of before. Typical automotive load cases for LS-DYNA implicit involve roof crush, door sag, misuse and other problems that are running over a long time span.

• Modeling composite materials with respect to reinforcement textile construction

  P. Böhler, M. Gubser, J. Ravic, O. Döbrich

  To address the ongoing efforts to virtually design complex composite materials and their high-perfor-mance structures and to contribute to the increasing developments towards Industry 4.0, research and development of fiber-reinforced composites is shifting from an experimental domain to a virtually con-trolled environment. Material models to account for the specific failure mechanisms of layered fiber-reinforced materials have been developed and can be used for largescale numerical structural simula-tions. However, these models do not account for the individual properties of the reinforcing materials and therefore lack information on microstructural effects and behavior.

• Modeling Crack Propagation in Rubber

  Yoav Lev, Konstantin Volokh (Faculty of Civil and Environmental Engineering)

  Traditional bulk failure models are based on the approach of continuum damage mechanics involving internal variables which are difficult to measure and interpret in simple physical terms. Alternative approach was proposed by Volokh [1-5], in which the function of the strain energy density was limited. The limiter enforces saturation – the failure energy – in the strain energy function, which indicates the maximum amount of energy that can be stored and dissipated by an infinitesimal material volume. The limiter induces stress bounds in the constitutive equations automatically. The work presents a numerical implementation of the energy limiter theory using the LS-DYNA ® user defined material. This approach will be tested in few examples. First, the FE subroutine is checked against a simple uniaxial tension case that can be solved analytically. Next, we will model the Deegan-Petersan-Marder-Swinney (DPMS) experiments [6-7] for the dynamic fracture of rubber. These tests use biaxial pre-stretched rubber sheets which are pricked at a point. The pricking initiates a crack which runs along the sheet. We simulate these tests using the user defined subroutines of the hyper-elastic material models enhanced with energy limiters. The numerical results regarding the crack shape and speed are compared to the test observations.

• Modeling Crushable Foam for the SAFER Racetrack Barrier

  Robert W. Bielenberg and John D. Reid - University of Nebraska-Lincoln

  One of the key components in the new SAFER barrier being installed at many IRL and NASCAR racetracks is the foam blocks placed between an outer steel tube structure and the existing concrete wall. Simple polystyrene insulation foams were proven to have good energy absorbing capabilities and were used as a primary means of energy absorption in the barrier. This foam is very low cost and easy to obtain. Foam research began with obtaining several samples of cubic foam blocks and then performing static and dynamic testing on them. Simulation of the dynamic test with LS-DYNA concentrated on the use of the *MAT_CRUSHABLE_FOAM material model. After successfully modeling of the bogie tests, the component model of the foam was placed in the full-scale model of the SAFER barrier. Later in the research program, the cubic shape foam blocks were replaced with a trapezoidal shape. These trapezoidal shapes were also tested and then, successfully simulated.

• Modeling Hailstone Impact onto Composite Material Panel Under a Multi-axial State of Stress

  M. Anghileri, L. Castelletti, A. Milanese, A. Semboloni - Politecnico di Milano, Italia

  Flying through a hailstorm is dangerous not only for the direct damages but also for the hidden damages which may concur to more serious accidents. In this work, hail impact onto composite structure under a multi-axial state of stress is investigated. Initially, a reliable model of a hailstone is developed referring also to the recent research on ice modelling. In parallel, a numerical model to predict delaminations in pre-stressed composite structures caused by low energy impacts is developed and validated against experimental data. Finally, the impact of the hailstone onto a composite structure is simulated.

• Modeling High Speed Machining with the SPH Method

  C. Espinosa, M. Salaun,C. Mabru,R. Chieragatti - Université de Toulouse, France, J.L. Lacome - LSTC, USA, J. Limido IMPETUS Afea, France

  The purpose of this work is to evaluate the use of the Smoothed Particle Hydrodynamics (SPH) Method within the framework of modeling high speed cutting. First, a 2D SPH based model is carried out using the LS-DYNA® software. SPH is a meshless method, thus large material distortions that occur in the cutting problem are easily managed and SPH contact control allows a “natural” work piece/chip separation. The developed SPH model proves its ability to account for continuous and shear localized chip formation and also correctly estimates the cutting forces, as illustrated in some orthogonal cutting examples. Then the SPH model is used in order to improve the general understanding of machining with worn tools. At last, a milling model allowing the calculation of the 3D cutting forces is presented. The interest of the suggested approach is to be freed from classically needed machining tests: Those are replaced by 2D numerical tests using the SPH model. The developed approach proved its ability to model the 3D cutting forces in ball end milling.

• Modeling Methodologies for Assessment of Aircraft Impact Damage to the World Trade Center Towers

  S.W. Kirkpatrick, R.T. Bocchieri, R.A. MacNeill, B.D. Peterson - Applied Research Associates, Inc., USA, Fahim Sadek - National Institute of Standards and Technology, USA

  The Federal Building and Fire Safety Investigation of the World Trade Center Disaster was recently completed by the National Institute of Standards and Technology (NIST). A critical component of the investigation was to analyze the aircraft impacts into the World Trade Center (WTC) towers to evaluate the impact-induced damage to the towers. This impact damage established initial conditions for the fire dynamics modeling, thermal-structural response, and collapse initiation analyses performed as part of the NIST investigation into the collapse of the WTC towers. This paper presents the development of the WTC tower and aircraft models and associated analysis methodologies used to simulate the aircraft impact response. The analyses performed span the range from laboratory-scale material testing up to the global aircraft impact response of the WTC towers. Simulations were performed at various levels of refinement. Component analyses were performed using small portions of the aircraft and tower. In these analyses, components were modeled with a fine resolution to investigate the details of the initial impact and breakup behavior. Results from the component analyses were used to develop the simulation techniques required for the global analysis of the aircraft impacts. The global impact simulation techniques were aimed at reducing the overall global model size while maintaining fidelity in the impact response. The accuracy of the calculated aircraft impact damage was evaluated by comparison with observed impact damage to the towers.

• Modeling Mine Blast with SPH

  John M. H. Puryear, David J. Stevens (Protection Engineering Consultants), Ryan M. Alberson (University of Texas), Pat McMahon (Land Systems-MTVR/LVSR)

  Accurately and efficiently modeling the loads applied to a vehicle by buried explosive (mine blast) is a persistent need. In this study, Smoothed Particle Hydrodynamics (SPH) was used to effectively model mine blast. The buried explosive and soil were modeled with SPH, while Lagrangian FEM elements were used for the vehicle plate. The approach was validated against a series of mine-blast experiments performed by the Ernst Mach Institute (Freiburg, Germany), in which the momentum applied to different geometries of steel plate suspended above the soil was measured. The momentum predicted from the SPH models ranged from 14% to 18% above the measured values, depending on plate geometry. Therefore, predictions from the SPH model corresponded closely with measured momentum but were conservative, as would be desired for designing vehicles. Furthermore, the SPH approach has the potential to be computationally efficient relative to an Arbitrary Lagrangian Eulerian (ALE) approach because an Eulerian solid mesh was not needed to model expansion of the explosive. This advantage is particularly important for models that include large vehicle targets, as an ALE approach would require large Eulerian meshes, significantly increasing the memory and execution time demands.

• Modeling Net Capture of an Object in LS-DYNA

  Lee-Hee Drory, Aviner Shreiber, Matan Elbaz, Omer Livneh

  One way of capturing a moving object is by using a hanged cage-like net. The process is to be reliable under various impact velocities and orientations of the captured body. Thus, accurately modeling its dynamics is vital due to the need to account for multiple probable outcomes while including the complex net structure. The focus of the present work is on the modeling, characterization and calibration of the net and its motion. To best represent the geometric properties of the net, its initial state, motion, and body capturing procedure, the following stages were carried out. First, a beam-element-based model of the net was constructed in MATLAB® using a generative function, that allows simple generation of a multiple-parameter dependent net structure. This was due to the need for flexibility in dimensions, geometric properties, part allocation and base unit cell shape. Second, mechanical properties of the hyper-elastic unique net structure were characterized by a series of tensile experiments followed by properly choosing LS-DYNA elements and material formulations. Finally, two sets of finite element analyses (FEA) were conducted, where the first included folding the net to determine its initial state for the successive impact simulation. Both folding and impact procedures required careful consideration and examination of different aspects, such as contact types and formulations, mechanical forces and damping.

• Modeling Non-Isothermal Thermoforming of Fabric-Reinforced Thermoplastic Composites

  D. Schommer, M. Duhovic, J. Hausmann (University of Kaiserslautern)

  The correct modeling of the sheet forming of fabric reinforced thermoplastic composites, so called organosheets, is still a challenge. In the past it was possible to predict accurately and efficiently the fiber orientation during the draping of dry reinforcement or constant temperature organosheet (reinforcement and molten polymer) using the explicit FEM-Software LS-DYNA®. Until now, the developed model was only able to simulate the right material behavior for an isothermal process. However, the draping of an organosheet is in reality a non-isothermal process that takes place at elevated temperatures.

• Modeling Nuclear Fuel Rod Drop with LS-DYNA®

  W. Zhao, J. Liu, W. Stilwell, B. Hempy, Z. Karoutas (Westinghouse Electric Company LLC)

  As a primary barrier to the fission product release, maintaining the structural integrity of fuel rod cladding has been a topic of great importance. To help better understand the structural behavior of the fuel rod in shipping and handling incidents, a detailed model for a typical pressure water reactor (PWR) fuel rod is being developed using LS-DYNA. The paper describes an on-going model development effort. For efficiency of the development process, a shortened version of the fuel rod is considered with full fuel pellet stack represented by five pellets. Nevertheless, the model contains all the structural features of the fuel rod, thus can be easily extended to obtain a full length fuel rod model.

• Modeling of a Cast Aluminium Wheel for Crash Application

  Y. Leost (Fraunhofer Insitut EMI)

  The modeling of wheels might have a strong influence on the vehicle response in crash simulation. The present work is about the development of a predictive cast aluminium wheel model for crash application. Coupons were directly extracted from the rim, spokes and the hub regions and experimental tensile and pressure tests were carried out to determine the material properties. The damage model GISSMO (Generalized Incremental Stress-State dependent damage Model), has been used in the material modeling to take into account the accumulation of damage, the influence of triaxiality and the mesh size dependency. Finally, the finite element model of the wheel has been validated thanks to component crash test. After some considerations about the appropriate element formulation for solids, the final simulation results are good correlated to experimental dynamic test in terms of load-displacement and failure modes

• Modeling of a Cross-Ply Thermoplastic for Thermoforming of Composite Sheets in LS-DYNA®

  Kari D. White, James A. Sherwood, Department of Mechanical Engineering, University of Massachusetts Lowell One University Ave., Lowell, MA 01854, USA

  Thermoforming is a very attractive process for the cost-effective high-volume production of high-performance composite parts. The process starts with an open-punch tool to produce a set of preforms. The preforms are then consolidated into a part using matched-tooling high-pressure compression molding. However, this process is prone to the formation of defects such as wrinkling of the plies as they conform to the compound-curvature geometries of the tool and poor consolidation of the set of preforms due to non-uniform thickness of the preforms. Thus, the processing options must be well understood, so the composite manufacturing process can be designed to mitigate wrinkling and to achieve full consolidation and thereby produce high-quality parts. The finite element method is well suited to give insight into how changes in the processing parameters such as binder pressure, temperature, tool speed, material properties and ply/ply and tool/ply frictions can impact part quality. A robust finite model can predict if and where wrinkles may precipitate and the degree of consolidation for a given set of process settings. Such a robust model requires a complete characterization of the mechanical behaviors of the material systems. The current research uses the temperature-dependent material properties of Dyneema® HB80, a cross-ply lamina sheet, and DuPontTM TensylonTM HSBD 30A, a bidirectional laminate tape, both known for their excellent ability to dissipate energy during impact, as inputs to a user-defined material model for LS-DYNA simulations. A hybrid discrete mesoscopic approach is employed to simulate the tensile and shear frame experimental characterization tests. Finite element simulations of the characterization experiments are compared to experimental results of the same to validate that the user-defined material model can replicate the experiments from which the material constants were derived. The current work shows excellent agreement between the model and the results from tensile and shear-frame experiments. Future work will incorporate material bending and ply/ply and tool/ply frictions. The ultimate goal is for the procedures that are used for conducting the material characterizations and for the process simulations that are developed in this research to be integrated into a Virtual Design Framework, where the part will be designed, manufactured and “tested” for field performance using a set of well-connected CAD/CAE tools, thereby minimizing the dependence on the design-build-test methodology.

• Modeling of Automotive Airbag Inflators using Chemistry Solver in LS-DYNA®

  Kyoung-Su Im, Zeng-Chan Zhang, and Grant Cook, Jr. (LSTC)

  Airbags are part of an important vehicle safety system, and the inflator is an essential part that generates a specific volume of gas to the airbag for a short duration of time. Recently, we have developed numerical models of automotive airbag inflators in conjunction with the LS-DYNA® chemistry solver. In this presentation, we will demonstrate two different models: a conventional pyrotechnic inflator and a compressed, heated gas inflator. Detailed and comprehensive descriptions for constructing the keyword flies will be given and the results for the two models will be discussed. Limitations of the currently available models and future directions for coupling with the existing LS-DYNA® solvers, i. e., ALE and CESE solvers will also be presented. In addition, more advanced models will be proposed and discussed in detail.

• Modeling of Ballistic Impact of Fragment Simulating Projectiles against Aluminum Plates

  T. Fras, L. Colard, B. Reck (French-German Research Institute of Saint-Louis)

  In this paper, the ballistic impact test is described in which fragment simulating projectiles (FSPs) have been used against thick plates made of an aluminum alloy. To perforate the plates, the projectiles must have reached velocities higher than 890m/s.

• Modeling of Bolts using the GISSMO Model for Crash Analysis

  F. Schauwecker (Daimler/University of Stuttgart), M. Feucht, M. Beck, D. Moncayo (Daimler), F. Andrade (DYNAmore), Prof. P. Middendorf (University of Stuttgart)

  The prediction accuracy of bolted connections is becoming increasingly important in the automotive sector. The requirements and thus the vehicle architectures are changing due to the electrification of vehicles and the high weight of batteries as well as their low permissible intrusion depth. Bolts are required as detachable fasteners to connect batteries with the body in white. The energy absorption concepts of vehicles with internal combustion engines have been continuously developed over the past decades. Thanks to many years of experience, the bolt connection behavior and load transfer are well known. Energy absorption concepts for electrically powered vehicles are in a comparatively early development phase. For the evaluation and further development of new crash concepts, a reliable simulation method is a basic requirement to predict joint failure in bolted connections.

• Modeling of Carbon-Fiber-Reinforced Polymer (CFRP) Composites in LS-DYNA® with Optimization of Material and Failure Parameters in LS-OPT®

  Sheng Dong, The Ohio State University;, Allen Sheldon, Honda R&D Americas, Inc;, Kelly Carney, George Mason University

  Carbon-fiber-reinforced polymer (CFRP) composite material has gained increasing popularity in aerospace, defense, automotive, and civil engineering. Its high strength-weight-ratio makes it efficient as a structural component. However, the structure of the layers of fibers oriented in different directions, together with the bonding matrix polymers, create challenges in crashworthiness modeling of CFRP parts as a standalone piece, not to mention when they are integrated into larger mechanical systems. This paper presents work done in modeling CFRP composite parts using MAT_58, a continuum mechanics damage material model in LS-DYNA. The parts are manufactured into different geometries, and have been crushed quasi-statically in axial and angled directions. The basic material properties in and transverse to the fiber directions, such as the elastic moduli, strains at failure, and plastic moduli among others are determined by simple coupon tests in tension, compression, and shear. However, by simply inputting values obtained from coupon tests in crush models of CFRP parts, there exist discrepancies between the simulations and tests. CFRP composites should be deemed more as structures rather than materials due to factors such as the bonding structure of the layers, the temperature-related softening, and the residual stiffness of the fibers after failure among others. In MAT_58, SLIM values of tension, compression, and shear are designated for capturing the residual strength of the material after failure as well as the temperature-related softening, both in and out of the fiber directions. Furthermore, MAT_ADD_EROSSION is added to activate element deletion based on individual tension, compression, and shear failures. As presented in this work, the system identification capabilities of LS-OPT can be used to calibrate such parameters to improve the correlation between the simulations and the tests. For an efficient optimization of the material parameters with LS-OPT a meta-model based optimization strategy with domain reduction has been applied. The objective for the optimization has been set to minimize the Dynamic Time Warping (DTW) distance between the force-time curves resulting from simulation and test, respectively. By using an LS-OPT setup that considers the match of multiple crush scenarios simultaneously an optimal parameter configuration can be identified that is more specific for the CFRP material characteristics and less sensitive to individual crush tests.

• Modeling of component failure due to notch effects in press-hardened steel caused by mechanical and thermo-mechanical joints under crash load

  P. Bähr (Fraunhofer IWM)

  The increasing application of press-hardened steel in combination with aluminum sheets in the construction of car bodies results in the use of mechanical joining techniques such as self-piercing riveting and thermo-mechanical joining techniques such as resistance element welding. These joints generally represent a notch within the component. The cause of the notch effect is different for the investigated joining techniques and can be distinguished in a geometrical notch and a metallurgical notch. Riveted joints result in a pierced hole with high plastic strains at the edge and thus represent a geometrical notch. Thermo-mechanical joints in press-hardened steel result in a softened heat affected zone (SHAZ) around the weld due to the applied heat during the joining process.

• Modeling of Cone Penetration Test Using SPH and MM-ALE Approaches

  Ronald F. Kulak, Cezary Bojanowski - Argonne National Laboratory

  The American Society of Association Executives (ASAE) Soil Cone Penetrometer Standard (S313.2) is designed to characterize general soil mechanical conditions. Its results are used predominantly for comparative purposes. Variations of this test are used for in-situ determination of the geotechnical engineering properties of soils and delineating soil stratigraphy. This paper presents a comparison between experimentally obtained results of cone penetration test with results from LS-DYNA®/MPP simulations performed on a high performance cluster computer. The previously reported experiments (conducted by USDA-ARS National Soil Dynamics Laboratory, Auburn, AL, USA) were performed on Norfolk Sand. These experiments show the variation in results for test conducted under identical conditions. In the LS-DYNA simulations, the soil was modeled using the material model MAT_005 Soil and Crushable Foam. Two approaches were used to represent the soil: a hybrid approach that combined Lagrange and Smoothed Particle Hydrodynamic (SPH) methods and the Multi Material Arbitrary Lagrangian - Eulerian (MM-ALE) method. The vertical resistance force versus penetration distance of the penetrometer cone was compared to the experimental results. A close match between numerical results and experimental data was obtained in the study for the Norfork Sand. The response simulated using the two numerical approaches were almost identical. A sensitivity study revealed that the penetrometer force was most sensitive to the soil density followed by sensitivity to a failure surface parameter.

• Modeling of Crazing in Rubber-toughened Polymers with LS-DYNA®

  M. Helbig, A. Haufe, DYNAmore GmbH, Industriestrasse 2, 70569 Stuttgart, Germany

  Rubber-toughened polymers such as acrylonitrile butadiene styrene (ABS) or high-impact polystyrene (HIPS) are composed of a thermoplastic matrix and small rubber particles, e.g. [1]. The enhanced fracture toughness and ductility, compared to the neat matrix material, are the advantages of rubber-toughened polymers [2]. These macroscopic effects are caused by mechanisms on the micro scale such as shear yielding, void growth and crazing. Crazing is understood as the formation of localized zones of fibrillated material which are able to transfer load. Stress whitening in combination with an increasing volumetric strain clearly indicates the crazing mechanism. The macroscopic volume typically stays constant during shear yielding. The yield and deformation behavior of a rubber-toughened polymer was characterized at the laboratory of DYNAmore GmbH, Stuttgart. For modeling of the dilatant deformation behavior MAT_SAMP-1 was used. Damage modelling depending on the deformation mechanism (shear yielding or crazing) can be taken into account via eGISSMO (i.e. *MAT_ADD_GENERALIZED_DAMAGE).

• Modeling of Curing Adhesives between Jointed Steel and Aluminum Plates using MAT_277 in LS-DYNA

  S. Dong (Ohio State University); A. Smith, A. Sheldon (Honda)

  In this paper, a sandwich structure of two jointed plates with an adhesive layer in between is simulated. A top plate of aluminum, and bottom plate of steel are jointed with rivets. Then the plates go through the oven for paint baking, which lasts for approximately 60 minutes with oven temperature increasing in the beginning, then keeping constant, and decreasing towards the end. The difference in thermal properties between the aluminum and steel causes different expansion rates between the top and bottom plates, which leads to plastic deformation at, and around the mechanical fasteners. A layer of adhesives is therefore employed between the two plates, aiming to increase the bonding and also to reduce the plastic deformation. However, both the chemical and mechanical properties of the adhesives change nonlinearly with temperature. Therefore, it is critical to model the properties of the adhesives properly so that the deformation of the sandwich structure can be predicted, and the stress distribution can be analyzed. A new material card in LS-DYNA, Mat_277 is used in this project for the adhesives. This material card relates the chemical and mechanical properties of the adhesives not to temperature, but to an intermediate parameter named degree of cure. The degree of cure is decided by both the time and temperature of the baking process. The entire process is simulated using the LS-DYNA implicit solver. Instead of imposing the temperature at all nodes, a thermal-structure coupled analysis is conducted by way of using the *Boundary_convection card. This allows the different thermal conductivities of aluminum and steel to be taken into consideration. It was found that the adhesive strength prior to full cure is critical in preventing the plastic deformation at the joints. With certain levels of pre-cure strength, the adhesive layer can increase the bonding between the two plates without delaminating, which in turn could allow less mechanical fasteners to be employed. The relationship between the properties of the adhesives and the number of mechanical fasteners needed is therefore studied. Simulation results are validated qualitatively with experimental data and good correlation is found.

• Modeling of Directional Focused Fragmentation Charge (DFFC) – Investigation of Different Approaches

  İsmet Kutlay ODACI, Samet Emre YILMAZ, İlker KURTOĞLU

  The aim of this study is to examine the effects of explosion-accelerated clusters of projectiles, which is in literature referred as Directional Focused Fragmentation Charge (DFFC), on target armor structures. The primary challenge in this study is to develop an accurate model for the explosive and fragments configuration, since the scenario involves a close-range explosion and fluid-structure interaction (FSI) due to the direct contact of fragments with the explosive. To find an appropriate and stable solution to this challenge, various techniques are explored for modeling both the explosive and the cluster of fragments.

• Modeling of Fuel Sloshing Phenomena Considering Solid-Fluid Interaction

  Jean Ma, Mohammad Usman - Plastics Products and Processing CAE Visteon Corporation

  The sloshing phenomenon in partially filled fuel tanks is more pronounced when vehicles experience a sudden start or stop. Sloshing is un-desired because it produces noise, high impact force on the tank walls and the challenge of low fuel handling. Today, the solution for containing sloshing is to incorporate baffles inside the tank. The presence of baffle dissipates the energy that is induced by the fuel motions. Design of baffles is a necessary step during the design of a fuel tank to meet required performance specification in service. A methodology to simulate sloshing phenomenon that incorporates solid-fluid interaction is presented in this paper. The methodology makes use of both Eulerian and Lagrangian formulation. Eulerian domain includes both air and fuel inside the tank, and the space around the tank. Lagrangian domain includes the tank shell and baffle structure. A concept of coupling surfaces is introduced in Eulerian domain to build the boundary of the inner and the outer of tank structure. The coupling surfaces also act as interactive surfaces between both Eulerian and Lagrangian domains to prevent penetration. A computational method is employed to simulate the sloshing phenomenon in tank when the vehicle is in motion. The simulation results are compared with the sloshing test results.

• Modeling of hypervelocity impact on spacecraft honeycomb-core sandwich panels: investigation of projectile shape and honeycomb-core effects

  A. Cherniaev , R. Aslebagh (University of Windsor)

  In a typical satellite bus, most impact-sensitive equipment is situated in the enclosure of the structural sandwich panels, often – panels with a honeycomb core (honeycomb-core sandwich panels, HCSPs). As commonly used elements in satellite structures, these panels form the satellite’s shape and are primarily designed to resist launching loads and provide attachment p oints for satellite subsystems [1]. With low additional weight penalties, their intrinsic ballistic performance can often be upgraded to the level required for orbital debris protection [2].

• Modeling of Microcellular Short Fiber Reinforced Plastics for Pedestrian Safety Analysis

  M. Landervik (DYNAmore Nordic), U. Westberg (Volvo Cars), S. Gastl (Borealis Polyolefine)

  For efficient vehicle development there is a strive to reduce prototypes and shorten development times which leads to the need to rely on CAE methods for continuous evaluation of product performance. This puts demands on the CAE methods, not only in terms of predictability but also in terms of how well they integrate in the development process. Model preparation, material characterization and computational costs are important aspects for successful integration. New materials and production methods are other drivers for CAE method development as current methods may not be adequate. Short fiber reinforced polymers (SFRP) have found their way into more automotive applications in recent years. Weight, the geometrical possibilities, part production cycle times and cost are some of the potential benefits. The injection molding process, however, leads to an inhomogeneous distribution of fiber orientation throughout a part. As the fiber orientation distribution has significant impact on the mechanical properties it causes anisotropy and spatial variations of the material response. This paper addresses the modeling of an SFRP part which is produced by gas assisted injection molding leading to a porous, microcellular, material consisting of three phases, i.e. matrix-, fiber- and pore phases.

• Modeling of Punctual Joints for Carbon Fiber Reinforced Plastics (CFRP) with *MAT_054

  Christian Liebold (DYNAmore GmbH, Germany), David Moncayo (Daimler AG, Germany)

  The increasing amount of carbon fiber reinforced plastic (CFRP) components used in the automotive industry opens new questions concerning the numerical modeling of different joining techniques for such materials. Design engineers already know that the beneficial properties of carbon fibers can be best used when considering the necessary joining techniques from the very first step in the preliminary design of a CFRP part. The anisotropical behavior of composites has to be fully considered in numerical simulations as well, especially when failure and partial damage occurs. Using experimental data from bearing tests loaded in different directions, different modeling techniques for structural joints are tested. The achieved correlation between simulation and experimental results will be discussed for a discretization relevant for industrial applications in a vehicle crash environment. Besides a qualitative and quantitative evaluation, the proposed modeling techniques are evaluated in terms of an appropriate representation of failure compared to the failure patterns observed during the experiments.

• Modeling of Self-Piercing Riveted Joints for Crash Simulation – State of the Art and Future Topics

  M. Bier, S. Sommer (Fraunhofer IWM)

  The requirements for energy efficiency and lightweight construction in automotive engineering rise steadily. Therefore a maximum flexibility of different materials is necessary and new joining techniques are constantly developed. The resulting large number of joints with different properties leads to the need to provide for each type of joint an appropriate modeling method for crash simulation.

• Modeling of Strain-Rate Dependence of Deformation and Damage Behavior of HSS- and UHSS at Different Loading States

  A. Trondl, D. Sun (Fraunhofer IWM)

  The predictive capability of crash simulation concerning material failure is still in need of improvement due to the coupled complex influences of triaxiality, strain rate and temperature. Because of their lower ductility the use of high- and ultra high strength steels (HSS&UHSS) requires a more accurate prediction of failure. This subject commonly leads to more complicated material- and failure models to describe complex interactions between deformation, strain rate and temperature, which usually results in longer computational time. On the other hand, due to the high complexity of crash simulation structures, simpler and less time-consuming material models and numerical methods are required to keep simulation times in an acceptable frame.

• Modeling of Thick UD Composites for Type IV Pressure Vessels

  R. Matheis, H. Murnisya (fka Aachen), T. Johansson (DYNAmore Nordic)

  Increasing energy costs, limitation of crude oil resources as well as constantly intensifying emission targets (especially w.r.t. CO 2 ) are a pivotal driver for current automotive research and development.

• Modeling of Vehicle Fuel via Smoothed Particle Hydrodynamics (SPH) Method in LS-DYNA® for Vehicle Crash Virtual Simulation

  Tushar Phule, Scott Zilincik (FCA US LLC)

  This paper describes advantages of modeling a fluid in a vehicle fuel tank using the Smoothed Particle Hydrodynamics (SPH) method in vehicle crash computer aided engineering (CAE) simulations in order to achieve appropriate fuel/fluid behavior during a crash event. SPH is a mesh free Lagrangian particle fluid modeling technique used for simulating fluid flows, whereas, the legacy CAE modeling method uses a solid tetra element mesh with MAT1F MAT_ELASTIC_FLUID to model the fluid in the fuel tank. The SPH method has many advantages over the legacy modeling method in terms of capturing important fuel tank responses, such as: correct tank internal fluid pressure, proper tank shell deformation, and tank clearances to the surrounding environment. Accurate simulation of these are important to meet NHTSA FMVSS 301 and fuel system integrity requirements. To compare the responses from the fuel tank, a study has been carried out by comparing SPH and legacy CAE methods with a physical test. The internal fluid pressure at the fuel tank control valve from a 35 mph flat frontal rigid barrier impact CAE model was plotted against a physical sled test that corresponds to the 35 mph flat frontal rigid barrier impact event. It was found that the SPH method provides better correlation over the legacy modeling method. In addition, tank shell deformation and tank clearances for both methods were compared with the physical sled test; It has been observed that the SPH method provides a more accurate tank shell deformation when compared to the legacy modeling method. There is an increase in computation time for the SPH method, however, this method ensures the result accuracy during fluid structure interaction.

• Modeling of Welded Structures Residual Strains

  Sergey Medvedev, Maria Petrushina, Oleg Tchij - National Academy of Sciences of Belarus

  This paper explores simulation techniques for prognosis residual strains of welded structures, which consist of common steel parts joined together by means of arc welding. The approach is based on longitudinal and transversal shrinkage forces, applied to the 3d-model of plastic weld zones. The calculations were made on ANSYS - LS-DYNA 970 MPP version on supercomputer SKIF-family located in United Institute of Informatics Problems of National Academy of Sciences of Belarus. The obtained results find good agreement with literature and practice data. Residual welding strains techniques approved for welding tubes, beams and some machine building constructions.

• MODELING of WELDING SEAM SEQUENCES

  Sergey Medvedev, Maria Petrushina, Oleg Tchij - National Academy of Sciences of Belarus

  This paper explores simulation techniques for prognosis residual strains of welded structures taking into account welding seam sequences. Simplified approaches of welding stress and strain theories were used and implemented on SKIF-family supercomputers. The elaborated program options allow to apply the fictitious shrinkage forces to the weld models of arbitrary space location. The results of the experimental computational verification of the proposed approaches are presented, welded structures models of complicated design being used. The obtained results meet good agreement with data obtained in the production processes and special literature.

• Modeling Plastic Clips in LS-DYNA® for Low-Energy Impact Analyses

  Kenneth E. Freeman, Alexander Gromer (DYNAmore Corporation), Brian O’Hara, Cameron O’Keeffe (Honda R&D Americas, Inc.)

  Through several different low-energy automotive impact simulations, it was discovered that capturing plastic clip behavior played a substantial role in predicting the system response. Therefore, a methodology for modeling plastic push-in rivets and snap-fit clip connections was developed in LS-DYNA for use in these low-energy automotive impact analyses. The required geometric discretization, contact definitions, material models and constraints that make up the models are discussed in detail. Pull-out force data was utilized to correlate the response and failure modes of the clip models. In addition, three different levels of clip model complexity were compared with respect to their suitability for different load cases. Simple clip model approaches were easy to pre-process and sufficiently captured most of pull-out failure modes. However, these did not capture shear or off-angle failure. More complex clip models sufficiently captured shear and off-angle failure, but come at a greater pre-processing and development effort. Lastly, some pre-processing methods are discussed to demonstrate how hundreds of clips can be incorporated in a model in very little time.

• Modeling Pre and Post Tensioned Concrete

  Leonard E Schwer (Schwer Engineering & Consulting Services)

  Modern concrete construction often uses pre-stressing of portions of the structure to improve the inherent tensile weakness of concrete. A compressive pre-stress is introduced into concrete using steel tendons loaded under tension. These tendons are either included in the concrete when the concrete is poured, i.e. pre-tension, or run through tubes that were cast in the concrete and then tensioned after the concrete is set, i.e. post-tensioned. Pre-tensioned components are often constructed off-site and shipped to the construction site. There are two types of post-tensioning: grouted or ungrouted. After the tendons are post-tensioned, the tubes containing the tendons may be back filled with grout (cement), this is primarily to minimize corrosion of the tendons. If grout is not used, then the tendons are typically lubricated, also to prevent corrosion.

• Modeling Rebar in Reinforced Concrete for ALE Simulations

  Shih Kwang Tay, Jiing Koon Poon, Roger Chan (Ministry of Home Affairs)

  A constraint based method to couple rebar in reinforced concrete has been a popular method for Lagrangian simulations. However modeling rebar in Arbitrary Lagrangian-Euler (ALE) concrete has not been widely documented. This paper aims to investigate the effectiveness of the two constraint based keywords, *ALE_COUPLING_NODAL_CONSTRAINT and *CONSTRAINED_LAGRANGE_IN_SOLID found in LS-DYNA ® to couple beam elements in ALE concrete. This paper also explores the option of explicitly assigning steel rebar material within the ALE concrete using *INITIAL_VOLUME_FRACTION to create a Multi-Material Arbitrary Lagrangian-Euler (MM-ALE) simulation.

• Modeling Rebar: The Forgotten Sister in Reinforced Concrete Modeling (v2)

  Leonard E Schwer (Schwer Engineering & Consulting Services)

  As part of the “Blind Blast Simulation Contest 1 ,” organized by the University of Missouri Kansas City, participants were invited to submit predictions of reinforced concrete slabs subjected to air blast loading. There were two classes of concrete: normal strength f c ′ = 5 ksi (34.5 MPa) and high strength f c ′ = 15 ksi (103.5 MPa). The normal strength concrete was reinforced with Number 3 Grade 60 steel bars with yield strength of 68 ksi (469 MPa). The high strength concrete was reinforced with Vanadium Number 3 bars with nominal yield strength of about 83 ksi (572 MPa). Each concrete slab design was subjected to two different air blast wave forms with impulses of about 5.38 and 7.04 MPa-ms. For the purposes of this reinforcement modeling study, the normal strength f c ′ = 5 ksi (34.5 MPa) concrete reinforced with Number 3 Grade 60 steel bars with yield strength of 68 ksi (469 MPa) will be considered. A description of the reinforced concrete slab and associated modeling is presented next. Interested readers should review the associated web site for additional details. The overall concrete slab dimensions are 64x33.75x4 inches (1625.6x958.85x101.6 mm) with a single layer of reinforcement, as shown in Figure 1, on the side of the slab away from the blast. The concrete slab fixture consists of a steel frame with front and back steel cross supports at the long ends of the slab. Figure 2 shows the final assembly of the blast side fixture over the concrete slab. The slab is mounted in the depicted removable end of a large air blast simulator.

• Modeling Rebound of Foam Backed Racetrack Barriers

  John D. Reid, Robert W. Bielenberg - University of Nebraska-Lincoln

  Modeling energy absorbing foams that restore back to their original shape can be extremely challenging, especially when the foam is crushed over 90%. However, the foam used in the SAFER racetrack barrier does indeed nearly return to its’ original shape after severe crushing. The desire to model this behavior led to the use of the Fu Chang foam model available in LS-DYNA .

• Modeling Self-Piercing Riveted Joint Failures in Automotive Crash Structures

  P.K.C. Wood, C. A. Schley - University of Warwick, England, M. Buckley - Jaguar and Land Rover, England, B. Walker, Ove - Arup and Partners, England, T. Dutton - Dutton Simulation, England

  This paper describes a new model and method to predict Self-Piercing Riveted (SPR) joint interlock failures in aluminium sheet at crash speeds using explicit finite element simulation. SPR interlock failure is dependent on rivet direction, which is included in the model. A mesh independent approach is adopted for connection model which is capable of industrial application at the full vehicle crash analysis level. The paper provides an overview of the approach to validate connection model; typically by developing detailed physics based models of various joint configurations supported with high speed experimental data, through to model capable of industrial application. The framework to validate joint failure model for use in crash simulation tools is expected to have broader application.

• MODELING SUSPENSION DAMPER MODULES USING LS-DYNA

  Jason J. Tao - Delphi Automotive Systems

  A suspension damper module is an integration of the vehicle chassis components that control suspension motion. Various analytical tools are currently used in vehicle suspension analyses and component designs. However, these tools are not particularly useful for analysis of proposed damper module designs since they typically do not accurately represent component interactions and force distributions within the module. This paper describes a finite element model of a suspension damper module using an explicit finite element code, LS-DYNA. The modeling techniques used to construct the components within the modular assembly are presented. The LS-DYNA model was first correlated with a side load test of the damper module on an MTS machine. The analysis results were also compared with those from an ABAQUS model of the same module. A parametric study was then conducted to investigate the effects of some design parameters on the piston side load in the damper system.

• Modeling the Axial Crush Response of CFRP Tubes using MAT054, MAT058 and MAT262 in LS-DYNA®

  leksandr Cherniaev, John Montesano, Clifford Butcher, Department of Mechanical & Mechatronics Engineering, University of Waterloo, 200 University Ave. West, Waterloo N2L 3G1, Canada

  Predictive capabilities of three LS-DYNA composite material models – MAT054, MAT058 and MAT262 – were investigated and compared with respect to modeling of axial crushing of CFRP energy absorbers. Results of crush simulations with non-calibrated material models were compared with available experimental data, and then parameter tuning was conducted to improve correlation with experiments. Furthermore, calibrated material models were used to conduct independent crash simulations with a distinct composite layup. Simulations with calibrated MAT054 predicted axial crush response of the energy absorbers with a reasonable accuracy. MAT058 was found to be intrinsically less accurate in predicting the peak force due to its inability to account for reduction of longitudinal compressive strength of a ply in the case of transverse compressive failure. It was also found that simulations with pre-calibrated MAT058 can predict non-physical failure modes, such as e.g. global buckling instead of stable axial crushing. Owing to complexity of its constitutive model, MAT262 required extensive calibration before a satisfactory agreement with experimental data could be achieved, which constitutes the major limitation of this material model. Instead of simple trial and error approach employed for other models, it was found more practical to use response surface approximation and gradient optimization in order to tune the parameters of MAT262.

• Modeling the Behavior of Dry Sand with DEM for Improved Impact Prediction

  S. Sridhar, S. K. Vishwakarma (Whirlpool of India)

  Pumpkin ball impact test is similar to simple pendulum impact test. It represents a rough handling test conducted on user interface parts to check its robusteness in case of abuse loading. The objective of this work is to create a standard simulation model that would capture the behavior of sand particles inside a rubber ball and scope is limited to create and validate a finite element model used to replicate a pumpkin ball impact test. Pumpkin ball is a rubber ball filled with dry sand up to 3/4th of its volume.

• Modeling the Effects of Laser Peening on Friction Stir Welding Residual Stresses

  Dr. Kelly Carney, Dr. Omar Hatamleh - NASA Glenn Research Center and Johnson Spaceflight Center

  An analytical framework for predicting the residual stresses which result from the laser peening of a friction stir welded sample, using the finite element software LS-DYNA®, is presented, using a 2195 Aluminum alloy as an example. The pressures resulting from the laser peening are directly applied in an explicit transient analysis as forces. At the completion of the transient analysis, an implicit springback analysis is performed to determine the final residual stresses. This cycle is repeated for the appropriate number of peen applications, including the appropriate overlap of application areas. To validate the analytical framework, a comparison of residual stresses between analysis and a test specimen is made using laser peened base material which was not friction stir welded. Friction stir welding causes residual stresses and material property variations which increase the difficulty of modeling beyond the already complex modeling of the laser peening. In the analysis, the varying material properties regions are somewhat simplified and defined as discrete, separate materials. The residual stresses resulting from the welding are introduced directly as initial conditions in the peening transient analysis and so are combined within the analysis with the residual stresses from the peening. An additional challenge in the modeling of laser peening is the uncertainty in the yield strength of metals at the very high strain rates (>5000 1/sec) which result from the very short loading pulse duration. The strain rate sensitivity of the example metal, Aluminum 2195, is low at strain rates of less than 5000 1/sec, but its behavior higher than this rate is unknown. The effect of this uncertainty in the very high rate behavior is studied parametrically.

• Modeling the Energy Absorption Characteristics of Wood Crash Elements

  E. F. Akbulut Irmak (Paderborn University)

  Wood is a natural and highly anisotropic material. Therefore, mechanical characteristics of the material depend on the direction and type of the load (e.g. deformation behavior of wood is ductile in compression and brittle in tension). The mechanical behavior of crash elements made of wood material was investigated experimentally and numerically at quasi-static and dynamic strain rates for load-carrying and energy absorption characteristics. For detailed investigations on the mechanical properties of wood, specimens were modeled and *MAT_WOOD (*MAT_143) was selected in LS-DYNA. The process of parameter identification for the *MAT_143 was clarified. In the scope of the experimental studies, quasi-static compression, tension and bending tests as well as dynamic drop tower tests were performed to characterize the material at low and medium strain rates, respectively. It was found that the investigated wood material is highly strain rate sensitive what can be captured by enhancing *MAT_143 by strain rate dependent fracture energy parameters. All material model parameters used in numerical studies were validated according to the experimental results for the *MAT_143. Since wood is a natural composite material, it was modeled with 2D shell element formulation and analyzed with single element simulations by composite material models by referring to material parameters used in *MAT_143. The investigated material models are *MAT_54, *MAT_58 and *MAT_261. The aim is to present a base study to enlighten the damage mechanism of wood for further investigations on the potential of wood-based structural automotive components.

• Modeling the Low Velocity Impact on Thick-Section Composite Cylinder

  Sang-Guk Kang, Bazle A. Gama, Shridhar Yarlagadda, John W. Gillespie Jr. - University of Delaware, Thorsten Schütz, Stephan Fell - Adam Opel GmbH

  Composite materials frequently have been applied to axi-symmetric filament-wound cylinder structures due to their specific stiffness and strength properties. When these structures are subjected to low-velocity impact (LVI), there exists a possibility of significant material damage which can drastically reduce the structural performance. The main objective of this paper is to predict the low velocity impact damage in thick composite cylinders using MAT162 progressive damage model implemented in LS-DYNA®. In this paper, damage prediction of a thick composite cylinder under low-velocity impact using uni-directional (UD) composite model of MAT162 is presented. A finite element model (FEM) of a thick composite cylinder with appropriate boundary conditions is developed to predict impact damages under different impact energies of a cylindrical steel impactor. Dynamic deformation, damage progression, and energy dissipation of the composite cylinder under LVI loading as a function of impact energy are presented.

• Modeling the Mechanical Behavior of a Li-Ion Pouch Cell under Three-Point Bending

  B. Schaufelberger, A. Altes, P. Matura (Fraunhofer EMI)

  Short-circuits caused by external forces, as they occur in crash situations, may lead to uncontrolled discharge of battery cells. As a consequence, the battery heats up locally, which, if it comes to the worst, results in an explosive reaction of the cell. However, the detection of critical deformations, for example in car crash simulations is very challenging: On the one hand, local indentations in the range of a few millimeters often result in a breakup of the inner structure and consequently in a short circuit. On the other hand, battery cells can also withstand surprisingly large deformations with the internal structure remaining intact. Thus, a reliable battery cell model has to capture a variety of different deformation modes.

• Modeling the Nonlinear, Strain Rate Dependent Deformation of Shuttle Leading Edge Materials with Hydrostatic Stress Effects Included

  Robert K. Goldberg, Kelly S. Carney - NASA Glenn Research Center

  An analysis method based on a deformation (as opposed to damage) approach has been developed to model the strain rate dependent, nonlinear deformation of woven ceramic matrix composites, such as the Reinforced Carbon Carbon (RCC) material used on the leading edges of the Space Shuttle. In the developed model, the differences in the tension and compression deformation behaviors have also been accounted for. State variable viscoplastic equations originally developed for metals have been modified to analyze the ceramic matrix composites. To account for the tension/compression asymmetry in the material, the effective stress and effective inelastic strain definitions have been modified. The equations have also been modified to account for the fact that in an orthotropic composite the in-plane shear response is independent of the stiffness in the normal directions. The developed equations have been implemented into LS-DYNA through the use of user defined subroutines (UMATs). Several sample qualitative calculations have been conducted, which demonstrate the ability of the model to qualitatively capture the features of the deformation response present in woven ceramic matrix composites.

• Modeling the Post-Peak Behavior for Crashworthiness Prediction of Composite Structures

  Xinran Xiao and Danghe Shi, Composite Vehicle Research Center, Michigan State University

  Composite structures exhibit superior specific energy absorption (SEA) than metallic structures. However, the application of composites in primary energy absorbing (EA) structures is still limited. The lack of reliable predictions for composite EA structures is considered to be one of the key factors. This paper discusses the importance of modeling the post-peak behavior in material models for crashworthiness prediction of composite EA structures and presents a model recently developed and implemented as a material subroutine in LS-DYNA®.

• Modeling the Press Hardening Process

  Prof. M. Oldenburg (Luleå University of Technology)

• Modeling Wire Rope Used in Cable Barrier Systems

  Cody S. Stolle, John D. Reid - University of Nebraska-Lincoln

  An improved LS-DYNA® model of 19-mm diameter 3x7 wire rope commonly used in roadside cable guardrail installations has been developed. A Belytschko-Schwer beam element was selected along with material *MAT_MOMENT_CURVATURE_BEAM. Based on physical testing, total axial load vs. true strain and bending moment vs. curvature were generated for use in the model. Since wire rope displays internal damping due to friction of strands and wires, damping was incorporated into the model using the LS-DYNA command *DAMPING_FREQUENCY_RANGE to damp low-frequency bending oscillations. The proposed model was implemented to simulate a dynamic bending test; results compared favorably.

• Modelisation of screen rupture during a mobile phone free fall

  C. Lacroix - Sagem Communication, Groupe Safran, France

  Sagem brand mobile phone enjoys a strong presence in world markets thanks to continuous technological innovations associated to a high level of quality. We will approach here the case of the mobile phone screen (LCD), major part of a mobile phone whose integrity must be ensured throughout the life of the product. The specifications sheet specifies strict standards concerning the shock resistance: LCD should not be damaged during a series of 2 X 10 falls at a determined height (corresponding to average human height). Answer of such requirements needs a best understanding and good analysis of the mechanical phenomena which appears in the LCD during the impact on the floor.

• Modelling and predicting spotweld failures in automotive crash structures

  Dr. P.K.C.Wood, Dr. C.A.Schley, Mr. R.Beaumont - IARC, University of Warwick, UK, Dr. B.Walker - ARUP, ARUP Campus, Blythe Valley Business Park, UK, Mr. T.Dutton - Dutton Simulation Ltd, Kenilworth, UK, Mr. M.A.Buckley - Jaguar Land Rover, UK

  The project has developed spotweld failure models capable of industry application for a range of steel grades to support development of automotive products, and their compliance to international crash safety requirements. An important consideration in this project is a requirement to balance the cost to develop the data input to models and their application capability in CAE based crash simulation tools to predict spotweld failures. Shear and tension spotwelded joint specimens in a variety of automotive sheet steel materials with thickness varying in the range 0.8 to 2 mm have been tested at low and high speed. The joint specimens have been spotwelded under controlled laboratory conditions and simulated factory assembly conditions to compare performance, and validate spotweld models for industry application. All specimens have been subjected to a heat treatment that simulates the paint bake conditioning applied to the BIW. All spotwelded specimens are tested under controlled laboratory conditions. At low rate, spotwelds are tested at 1 mm/s and these may be referred to as quasi-static tests. At high rate, spotwelds are tested at 2 m/s and these may be referred to as dynamic tests. Accordingly test procedures were developed and refined to support the development of quasi-static and dynamic test results. In total some two hundred tests were performed. A method to characterise the test results, and calibrate models to predict spotweld failure under quasi- static and dynamic-impact conditions is described.

• Modelling and predicting spotweld failures in automotive crash structures

  Dr. P.K.C.Wood, Dr. C.A.Schley, Mr. R.Beaumont - IARC, University of Warwick, UK, Dr. B.Walker - ARUP, ARUP Campus, Blythe Valley Business Park, UK, Mr. T.Dutton - Dutton Simulation Ltd, Kenilworth, UK, Mr. M.A.Buckley - Jaguar Land Rover, UK

  The project has developed spotweld failure models capable of industry application for a range of steel grades to support development of automotive products, and their compliance to international crash safety requirements. An important consideration in this project is a requirement to balance the cost to develop the data input to models and their application capability in CAE based crash simulation tools to predict spotweld failures. Shear and tension spotwelded joint specimens in a variety of automotive sheet steel materials with thickness varying in the range 0.8 to 2 mm have been tested at low and high speed. The joint specimens have been spotwelded under controlled laboratory conditions and simulated factory assembly conditions to compare performance, and validate spotweld models for industry application. All specimens have been subjected to a heat treatment that simulates the paint bake conditioning applied to the BIW. All spotwelded specimens are tested under controlled laboratory conditions. At low rate, spotwelds are tested at 1 mm/s and these may be referred to as quasi-static tests. At high rate, spotwelds are tested at 2 m/s and these may be referred to as dynamic tests. Accordingly test procedures were developed and refined to support the development of quasi-static and dynamic test results. In total some two hundred tests were performed. A method to characterise the test results, and calibrate models to predict spotweld failure under quasi- static and dynamic-impact conditions is described.

• Modelling and Simulation of Hypervelocity Impacts on Spacecraft in Low Earth Orbit

  R. Færgestad, J. K. Holmen, T. Berstad (NTNU) T. Cardone (ESA), K. A. Ford (NASA), T. Børvik (NTNU)

  Orbital debris is an increasing threat to current and future missions in low Earth orbit (LEO), and spacecraft shielding is vital for future space exploration efforts. Experimental hypervelocity impacts (HVI) are expensive and can only be performed at a few laboratories worldwide, making numerical simulations an essential tool in the development and design of debris shields. A debris shield is a sacrificial plate that shatters an impactor into a cloud of particles, distributing the momentum of the impactor over a large area, thus preventing it from perforating the spacecraft. In this study, HVI were modelled in LS-DYNA using a coupled finite element-discrete particle method (FEM/DES), through the *DEFINE_ADAPTIVE_SOLID_TO_DES keyword. The results were compared to experimental data from the literature as well as to simulations applying the smoothed particle hydrodynamics (SPH) method. First, impacts by projectiles with diameter below 1 cm and impact velocities up to 6.7 km/s were simulated to study the debris cloud after perforation of a single plate. Here, aluminium alloy AA6061-T6 was used as both the target and the projectile material. The FEM/DES method was able to predict the shape of the debris cloud as a function of impactor shape, impactor velocity and shield thickness. Then, the FEM/DES method was applied to a dual-wall Whipple shield configuration and was able to accurately describe the damage from the debris cloud on the rear wall.

• Modelling Back Face Deformation of Woven Layered Composite Targets under Oblique Impact

  M. Seidl, N. Faderl, M. Becker (ISL)

  Body armour is the only protection a dismounted soldier has against projectiles or fragments in case of combat. Perforation is prevented in body armour as the kinetic energy of the projectile is transformed to deformation work in the armour material. This dynamic material response upon impact is especially crucial for helmets, as it acts directly on the human head. One potential threat nowadays a foot soldier faces during missions is the 7.62x39 mm projectile fired from a rifle. Helmets are not designed to withstand a direct impact of such a projectile, which is launched at an initial velocity of vi=720+/10 m/s. Under an obliquity angle of θ>65 degrees (NATO) projectile ricocheting is observed. The aim of the ongoing project is to promote the projectile ricochet off helmets to increase the likelihood of projectile deflection and the survivability of the wearer. The focus of this paper is the target back-face deformation (BFD) upon oblique high velocity impact. Experiments were conducted on projectile impact on plane aramid plates. These plates have the same material properties, such as layer number, as used for manufactured helmets – other ballistic helmet materials are covered in future research. Upon impact, the dynamic BFD of the aramid targets was measured, using digital image correlation (DIC). Additionally, the experiments were repeated to capture the projectile trajectory through the target thickness, using X-ray cinematography. The BFD and trajectory results are used for the qualitative comparison of a numerical model, defined within the LS-DYNA® explicit Lagrangian solver. Model components, the projectile and target plate are defined using fully integrated hexahedral elements. The projectile deformation is represented by *MAT_JOHNSON_COOK and its failure criterion; and the target plate is represented by *MAT_COMPOSITE_DAMAGE. The projectile and the composite target are in a symmetric contact defined by *CONTACT_ERODING_SURFACE_TO_SURFACE. The aim of this paper is an investigation on the most suitable modelling approach for a numerical validation of the BFD response obtained from the DIC measurements. This work is a first step to implementing experimentally and numerically achieved BFD data in a LS-DYNA® Finite element (FE) head model, using a head injury criteria (HIC).

• Modelling Carpet for Use in Occupant Crash Simulations

  Dylan Thomas - Honda R&D Americas

  Prediction of occupant injury using crash simulations can require numerical representation of materials that are not normally included within the structural model. Intuitively, it makes sense that the carpet would be required to predict the tibia index during frontal crash events; however, there appears to be little published on the topic. The tibia index is an injury criteria that needs to be predicted during IIHS frontal offset occupant simulations, but is also be looked at during unbelted FMVSS 208 simulations. Since carpet behaves quite differently during compressive and tensile loading, a numerical representation that can stably capture both regimes during occupant modelling is needed. This paper outlines a method to model the carpet using a specific meshing method and two material models. Shell elements in combination with the *PIECEWISE_LINEAR_PLASTICITY material model are used to model the tensile load carrying capacity of the carpet, while brick elements with the *MAT_FU_CHANG_FOAM material model are used to represent the compressibility of the carpet. Validation of using this modelling method with test data is presented, as well as the application of the carpet model in larger occupant models.

• Modelling Delamination in Fibre-Reinforced Composites subjected to Through-Thickness Compression by an adapted Cohesive Law

  Moritz Kuhtz, Johannes Gerritzen, Jens Wiegand, Andreas Hornig, Maik Gude

  A special form of failure in impact loaded Fibre-Reinforced Composites (FRP) structures is delamination, in which individual layers of a laminate get separated from one another. In contrast to the continuum mechanically formulated models of damage mechanics, the description of delamination processes is based on concepts of fracture mechanics. Here, delamination initiation is due to interlaminar stresses [1], whereby the tolerable interlaminar shear stresses can be increased by a simultaneous through thickness compression (TTC) [2-4]. Furthermore, an increase in the critical energy release rate with increasing out-of-plane compressive load is described [5-6]. Failure to consider the compressive superposition can lead to an overestimation of the delamination failure in impact loaded FRP structures such as three-point bending beams [7].

• Modelling internal gas flows in a single stage gas gun using Eulerian/Lagrangian coupling in LS-DYNA

  Marina Seidl, Kevin Hughes, Tom De Vuyst (Cranfield University)

  Most research on gas guns for impact testing investigates the velocity reached by the projectile or sabot when it hits the target. In this research attention is paid to the effect of initial loading conditions on the velocity reached by the projectile upon exit from the barrel. The work is focussed on the single stage nitrogen gas gun at the Department of Applied Mechanics in the School of Engineering at Cranfield University of this research. This gas gun was used to generate test data for a range of initial pressures in the pressure vessel. An LS-DYNA model of the gas gun which uses the Eulerian/Lagrangian coupling feature is described. The LS-DYNA model results, as well as results from an analytical model, are compared to the test results. The results indicate that, while the analytical model over predicts the projectile velocity, the LS-DYNA model is capable of accurately predicting the projectile velocity as a function of the initial pressure in the pressure vessel. The results also indicate that the opening time of the valve affects the projectile velocity at higher initial pressures.

• Modelling Laminated Glass in LS-DYNA under Extreme Loading Conditions

  M. Tatarsky, D. Aggromito, J. Farley, J. Klimenko, W. Wholey, L. Pascoe (Arup)

  In the event of an explosion in a populated urban area, fragmentation from glass is a significant contributor to human injury. The mitigation of glass fragmentation hazards is well-established through the use of laminated glass featuring a polymer interlayer, such as DuPont Sentry Glass Plus (SGP) or polyvinyl butyral (PVB). These interlayers work by exploiting the inherent viscoelastic and adhesive properties of the polymer, providing a mechanism to dissipate the energy of the blast through work done in deformation of the interlayer while retaining fragments of broken glass. This behaviour is fundamental to limit the projection of fragments of otherwise brittle glass, thereby reducing or eliminating highly hazardous secondary fragmentation associated with glazing.

• Modelling liquefaction of soils with LS-DYNA using a SANISAND-based material model

  R. Sturt, C. Cengiz, Y. Huang, S. Bandara, A. Pillai, J.Go (Arup)

  Saturated sandy soils can be prone to liquefaction during earthquakes: the soil loses strength and stiffness due to cyclic shear loading, becoming more like a liquid or quicksand. When liquefaction occurs, structures founded on such soils may experience severe damage or large settlement, or may even overturn. Designers of structures in seismically-active regions where liquefiable soils are present need to assess the likelihood of liquefaction occurring under design-level earthquakes and, if required, provide mitigating measures in the design. Three-dimensional nonlinear finite element analysis can be used to understand the effects of liquefaction on a structure and, if sufficient validation of the soil properties has been carried out under a range of stress conditions, can potentially predict the extent of liquefaction that will occur as a result of a given earthquake time-history. However, this requires a soil material model capable of reproducing the phenomena relevant to liquefaction.

• Modelling of Adhesively Bonded Joints with *MAT252 and *MAT_ADD_COHESIVE for Practical Applications

  F. Burbulla (Porsche AG), A. Matzenmiller, U. Kroll (IfM, University of Kassel)

• Modelling of an automobile tyre using LS-DYNA3D

  W. Hall, R. P. Jones, J. T. Mottram - University of Warwick

  This paper describes a finite element model used to investigate the quasi-static behaviour of a stationary automobile tyre vertically loaded against a stiff horizontal surface. The model includes a representation of the tyre, a steel wheel and surface. The tyre is represented in detail by a number of tyre components, the wheel and surface are coarsely modelled. LS-DYNA3D is used to simulate the inflation of the tyre, the fit between the tyre and the wheel and the vertical loading of the tyre against the surface. Simulation results, such as the load-deflection characteristics and the load-tyre/ground contact patch dimensions are compared with mixed success to those obtained experimentally. The stiffness of the tyre components and the inflation pressure are varied independently and the simulation is repeated. The resulting load-tyre/ground contact patch dimensions are discussed in context with the development of a rolling tyre model.

• Modelling of Armour-piercing Projectile Perforation of Thick Aluminium Plates

  Kasper Cramon Jørgensen, Vivian Swan (NIRAS A/S)

  This study investigates the perforation process of armour-piercing projectiles on commercially available high-strength aluminium. A LS-DYNA® model is developed with thick target plates of aluminium alloy 7075-T651 and an incoming 7.62 mm armour-piercing projectile with an impact velocity of 850 m/s. A numerical formulation combining classic Lagrangian finite elements with an adaptive mesh algorithm is utilized to overcome large deformation challenges and more accurately predict failure mechanisms. Both aluminium target and projectile have been modelled as deformable with a modified version of the Johnson-Cook strain-rate and temperature dependent plasticity model, based on input parameters from literature. Main model results include projectile residual velocity after target perforation and prediction of target failure mechanism. The model results are validated against experimental results from live ballistic tests and a sensitivity study is carried out to identify influential material model parameters.

• Modelling of Bonded Component Tests, Comparing MAT_240 to State of the Art Models

  J. F. Berntsen, D. Morin, A. Holm Clausen, M. Langseth (NTNU)

  Modelling of adhesively bonded joints is still an active field of research, aiming for a more accurate description and simpler calibration processes without significant increase in computational costs. There are two different approaches typically applied to model adhesives depending on the size of the problem and required accuracy. For smaller problems where the computational cost is of less relevance, the adhesive line can be finely discretized and modelled with a mesoscopic material model. This mesoscopic model is characterized by a constitutive law describing the relation between stresses and strains in the material.

• Modelling of damage in composite materials using interface elements

  W.G. Jiang, S.R. Hallett, M.R. Wisnom - University of Bristol

  A simple and robust implementation of an interface element has been addressed in this paper. A new state variable is introduced to trace the extent of damage accumulated at the interface. The element not only simulate mixed mode delamination propagation in composite materials but also satisfactorily deals with mode ratio change during the debonding process. The interface model is implemented in LS-DYNA code. The model has been applied to scaled open hole tension tests. Comparison between numerical results and experiments shows good correlation.

• Modelling of ductile failure in metal forming

  H.H. Wisselink, J. Huetink - Materials Innovation Institute (M2i) / University of Twente

  Damage and fracture are important criteria in the design of products and processes. Damage mod- els can be used to predict ductile failure in metal forming processes. Nonlocal models avoid the mesh dependency problems of local damage models. A nonlocal damage model has been implemented in LS- DYNA using the user-subroutines UMAT and UCTRL1. The implemented model will be compared with results obtained with the available option in LS-DYNA to combine *MAT PLASTICITY WITH DAMAGE with *MAT NONLOCAL. Advantages and disadvantages of the different implementations will be dis- cussed. The user nonlocal damage model has been applied to a bending and a blanking process. Results of these simulations will be shown.

• Modelling of ductile failure in metal forming

  H.H. Wisselink, J. Huetink - Materials Innovation Institute (M2i) / University of Twente

  Damage and fracture are important criteria in the design of products and processes. Damage mod- els can be used to predict ductile failure in metal forming processes. Nonlocal models avoid the mesh dependency problems of local damage models. A nonlocal damage model has been implemented in LS- DYNA using the user-subroutines UMAT and UCTRL1. The implemented model will be compared with results obtained with the available option in LS-DYNA to combine *MAT PLASTICITY WITH DAMAGE with *MAT NONLOCAL. Advantages and disadvantages of the different implementations will be dis- cussed. The user nonlocal damage model has been applied to a bending and a blanking process. Results of these simulations will be shown.

• Modelling of Ductile Polymer Model for Crash Application

  Y. Ngueveu, S. Miyagano (Toyota); F.Lauro Universite de Valenciennes); R. Balieu (KTH Royal Institut of Technology)

  Due to their lightweight and mechanical properties, ductile polymers are widely used in automotive industry. Those polymers play an important role during pedestrian protection performance as they are designed to absorb some of the energy induced by the collision with the pedestrian. To achieve a good and robust design fulfilling our target, CAE simulations are used. However, a mismatch between CAE results and experimental test can arise, leading to an extra loop in the development process. Root cause analysis showed us that it occasionally comes from the CAE model of polymer. Current CAE material model for polymer still needs some improvements in order to capture mechanical phenomena exhibited by polymer during those impacts (Visco elasticity, pressure dependent plasticity, etc…). We have developed a new material model considering all those phenomena [1] [2]. To validate this model, simulations were performed using LS-DYNA, and correlated with experimental tests. Tests were conducted, firstly to validate features implemented in this new model, secondly to check its effectiveness with complex loading case, and finally to verify its accuracy for vehicle development. The newly developed model correlated well with experimental test and improved our CAE accuracy for pedestrian protection performance. This shows that we are in the good direction to improve our CAE capability. This comes however with a trade-off which is the increase of CPU cost. A more thorough investigation is being done to check whether or not the CPU cost can be reduced.

• Modelling of Foams using MAT83 - Preparation and Evaluation of Experimental Data

  Enver Serifi - Universität Stuttgart, Andreas Hirth, Stefan Matthaei - DaimlerChrysler AG, Heiner Müllerschön - DYNAmore GmbH

  Foam materials are widely used in automotive industry such as energy absorbers and comfort enhancers. Because of high energy absorbing capability of foams, they became very important in vehicle crashworthiness. So in this manner, FE modelling of foam materials also becomes important. Although foam materials are very promising materials, not that much study has been done about foams comparing to other commonly used materials like steel, etc. Some different approaches are available to define the behaviour of foam materials. One micro-structural approach to define the mechanical behviour of foam materials, considers the foam material as a cubic model and uses the standard beam theories with solid-fluid interaction to describe the in- and out-flow of fluid inside the foam material(see Gibson and Ashby [1]). There are also macro-structural approaches those consider the foam material as a continuum with solid-fluid interaction in order to describe the in- and out-flow and pore-fluid in the foam material (e.g. Ehlers [2]). In contrast to such quite sophisticated models, in LS-DYNA for practical engineering pruposes the foam model *MAT_FU_CHANG_FOAM (MAT83) is available. The main assumption of MAT83 is, that Poisson's ratio is equal to zero for foams and therefore no coupling between the material axes is present. This leads to a one-dimensional material law, where experimental curves of uni-axial test can be used directly.

• Modelling of Foams using MAT83 – Preparation and Evaluation of Experimental Data

  Enver Serifi - Universität Stuttgart, Andreas Hirth, Stefan Matthaei - DaimlerChrysler AG, Heiner Müllerschön - DYNAmore GmbH

  Foam materials are widely used in automotive industry such as energy absorbers and comfort enhancers. Because of high energy absorbing capability of foams, they became very important in vehicle crashworthiness. So in this manner, FE modelling of foam materials also becomes important. Although foam materials are very promising materials, not that much study has been done about foams comparing to other commonly used materials like steel, etc. Some different approaches are available to define the behaviour of foam materials. One micro-structural approach to define the mechanical behaviour of foam materials, considers the foam material as a cubic model and uses the standard beam theories with solid-fluid interaction to describe the in- and out-flow of fluid inside the foam material (see Gibson and Ashby [1]). There are also macro-structural approaches those consider the foam material as a continuum with solid-fluid interaction in order to describe the in- and out-flow of the pore-fluid in the foam material (e.g. Ehlers [2]). In contrast to such quite sophisticated models, in LS-DYNA for practical engineering purposes the foam model *MAT_FU_CHANG_FOAM (MAT83) is available. The main assumption of MAT83 is, that Poisson’s ratio is equal to zero for foams and therefore no coupling between the material axes is present. This leads to a one-dimensional material law, where experimental curves of uni-axial test can be used directly. The aim of this work is to provide a method and to develop a computer program in order to generate reliable input data for the simulation of EPP foam with MAT83 in LS-DYNA. Experimental raw data have to be prepared and extended respectively. In addition, suitable density laws have to be developed in order to provide LS-DYNA input data for intermediate densities, where no experimental data are available. To verify the reliability of the results, simulations with the generated curves are compared to an independent experimental database and to some real experimental applications.

• Modelling of Fracture Initiation and Post-Fracture Behaviour of Head Impact on Car Windshields

  K. Osnes (NTNU), S. Kreissl, J. D’Haen (BMW Group), T. Børvik (NTNU)

  More than half of all road fatalities involve vulnerable road users, such as pedestrians and cyclists [1]. When involved in crashes with cars, the head is particularly susceptible to injuries, and especially if the road user hits the windshield of the car [2]. Impact tests are often performed to estimate the risk of head injury during such an event. A pedestrian head strike test normally involves a spherical headform, in which the likelihood of head injury is described by the head injury criterion (HIC) [3].

• Modelling of Hot Rotary Kiln

  D. Ramanenka, G. Gustafsson, P. Jonsen (Lulea University)

  Rotary kilns are the central part in the production of many important materials, such as: cement clinkers, lime for paper production and iron-ore pellets for steel making. The main design of a rotary kiln is rather simple – consisting of a cylindrical steel casing and one or several layers of refractories in order to protect the casing from high service temperatures. The dimensions of a rotary kiln vary between some 10 to 180 m in length and 2 to 8 m in diameter. Damage to the refractory lining is common and can potentially lead to long-lasting production shut-downs and high production losses. Due to the harsh inner environment and the large dimensions of the kiln it is difficult to observe and evaluate the kiln while in service – hindering improvement of the kiln. Therefore, it is advantageous to perform computer simulations and potentially improve the design of refractories (bricks), the material choice and operation of the kiln based on the numerical results. In this work LS-DYNA is used for simulation of a hot rotary kiln insulated with a single lining of refractory bricks. A cross-section of a kiln of approximately 8 m in diameter is modelled. The physical time to model is up to 65 h. The model is time-dependent and includes thermal expansion and rotation of the kiln. Heat transfer coefficients are calibrated by LS-OPT. It is found that modelling of a hot rotary kiln is rather successful but several challenges exist. Calculation time can in some cases reach 2-3 weeks (implicit, MPP, 16 cores). Instabilities due to contact associated problems is common. The created model facilitates decision making regarding e.g. heating/cooling procedure, design changes, maintenance frequency and more.

• Modelling of laser impact on typical composites aeronautical structures for bonding quality assessment

  Julie Rougier, Teddy Maillot, Charlotte Michel, Vincent Lapoujade

  Massively used in aeronautical structures, composites are nowadays essential in the search for a more ecological and successful industry. Their low density enables weight reduction and then decreases airplanes consumption. However, the current composites assembly process represents a limitation in their use. In fact, we do not have any reliable, industrialized and non-destructive technology to control the adhesive quality. Then composites are also riveted which adds weight and a drilling process during which fibres can be locally damaged. For about 10 years, the LASAT (LAser Shock Adhesion Test) technology appears to be a promising alternative as a non-destructive control mean to asses bonding quality. The laser impact creates a plasma that induces shock waves propagation in the structure. The LASAT technology can also be used to generate damage anywhere in the assembly thickness. The experimental technology is mature but is lacking a numerical tool in order to calibrate the input laser parameters depending on the targeted results.

• MODELLING OF MATERIAL BEHAVIOUR AND FRACTURE FOR ALUMINIUM ALLOYS WITH APPLICATIONS TO PLASTIC FORMING AND CRASHWORTHINESS

  Odd Sture Hopperstad, Torodd Berstad, Odd-Geir Lademo, Magnus Langseth - Norwegian University of Science and Technology

  Constitutive models and failure criteria for aluminium alloys have been formulated and implemented in LS-DYNA for corotational shell elements. The applications are largescale simulations of plastic forming and crashworthiness. The constitutive models include plastic anisotropy, non-linear isotropic and kinematic hardening, strain-rate effects and simple fracture criteria. A non-local instability criterion is used to determine the onset of strain localization. Predictions of plastic instability and fracture are mesh dependent. To reduce this problem, non-local thinning has been introduced. Some aluminium alloys exhibit the Portevin-Le Chatelier effect or serrated yielding. This is caused by negative steady-state strain rate sensitivity. A simple model for dynamic strain aging is included in the models to account for this phenomenon. Examples of the use of the models in prediction of formability, plastic forming, welded connections and crashworthiness are given.

• Modelling of Polypropylene Subjected to Impact Loading at Low Temperatures

  E. Schwenke (NTNU)

  The use of thermoplastics in structural applications requires that engineers can reliably predict their mechanical behaviour. Depending on the intended use, a component must withstand various load cases and environmental factors. This paper seeks to investigate the capabilities of a phenomenological material model to represent polypropylene (PP) plates subjected to a dropped weight impact at low temperatures. The dropped weight tests were performed with an Instron CEAST 9350 Drop Tower Impact System, shown in Figure 1. An incorporated environmental chamber injected with liquid nitrogen enabled sub-room temperature conditions. A total of 11 drop tests were made at five different impact velocities. The material was found to experience moderate plastic deformations until failure through plugging. By comparison of force displacement curves, the tests are found to show good repeatability. Some variations are found with respect to initiation of failure, possibly caused by small variations between the plates or misalignments during tests.

• Modelling of the deformation and fracture behaviour of laser welds for crash simulation

  Silke Sommer - Fraunhofer Institut Werkstoffmechanik IWM, Frederik Klokkers - Laboratorium für Werkstoff- und Fügetechnik LWF

  The light weight potential in automobile fabrication is increasing due to the development of new high strength steels. The realisation of this potential requires the use of adjusted joining techniques for the combination of optimized material properties with optimized joint properties. With the development of laser welding to a series-production technology a joining technique is available to practise the light weight potential of high strength steels. The advantages of laser welding compared to conventional welding techniques are the high process velocity, the low thermal influences of the material and the flexibility in joint figure and position [1, 2]. The flange width can be reduced that leads to weight reduction and design advantages. Softening in the heat affected zones beside the welds is avoided because of the compressed heat input during laser welding. The strength of the high strength steels remains in the joint. The application of laser welding is increasing for joining automotive components to the body in white [3]. But laser welding is less used compared to conventional joining techniques like spot welding. The reasons are the missing knowledge about crash worthiness of laser welds and missing methods to model the laser welds in crash simulation. The questions are how laser welds behave under crash loading: What are the experimental methods for a reliable characterisation? What are the numerical methods for an efficient simulation of the load-bearing capacity of the joints? A working group of FAT AK27UA crash and occupants simulation initiated a research project to answer these questions. Two different weld geometries of laser welded step welds were investigated. Those are short linear and c-shaped welds as single parts of the step welds. The investigations of the laser welded joints are done using two different steel kinds. First a low strength steel, DC04, with a tensile strength of about 300 MPa and second a high strength steel, TRIP700, with a tensile strength of about 670 MPa are used. The laser welding of the 1.5 mm and 2.0 mm thick steel sheets was done by Daimler Forschung in Ulm, Germany. Metallographic investigations of the welds were done. The welds were cutted and grinded and hardness profiles were measured over the weld. The average hardness was about 200 HV0.1 in the weld metal of DC04 linear welds compared to 100 HV0.1 in the base metal. The average hardness was about 470 HV0.1 in the weld metal of TRIP700 linear welds compared to 215 HV0.1 in the base metal. The width of the linear laser weld was about 1 mm and the length of the single linear laser weld was about 18 mm. Single welds were characterised using different specimen geometries to realise different loading situations like shear, tension, bending and combined shear-tension (KSII-0°,-30°,-60°,-90°, coach-peel and shear-tension specimens). For investigation of strain rate effects the loading velocity has been varied between quasi-static and 1.5 m/s. The load bearing capacity of the DC04 linear laser weld under shear-tension and KSII-0° are less (about 10 %) than under tension (KSII-90°) loading. The linear laser weld is shear loaded in weld direction with the KSII-0° specimen and perpendicular to the weld direction with the shear-tension specimen. In both shear loading cases the weld fails through interfacial fracture. In all other loading situations like KSII-90°,-30°,-60° and coach-peel the welds were buttoned out or peeled out of the connection. While investigating the linear welds in TRIP700 some changes in fracture mode occurred. Here, interfacial fracture occurred also in other loading situation especially under bending loading in the coach-peel specimen test. The scattering of load bearing capacity is higher as a result of the changes in fracture mode compared with the results in DC04 steel. For investigation of the local loading situation a detailed model with solid elements for the sheets and the weld is used containing different material zones for base metal, heat affected zone and weld metal. The result of this detailed simulations was, that the loading in the weld line is not homogeneous. For example under tension loading, KSII-90°, there are high normal stresses located in the base metal at the ends of the linear weld. The distribution of loading is also seen in a simplified model. Here the laser weld of 18 mm length is modelled using five connected solid elements. The metal sheets are modelled with shell elements, of course. The elastic-plastic material model *MAT_024 without failure strain is used for the shells. The cohesive material model *MAT_ARUP_ ADHESIVE is used for the solid elements of the laser weld defined here as cohesive elements. The fracture parameters of *MAT_ARUP_ADHESIVE are determined with simulation of shear-tension and KSII-90° tests taking into account the local distribution of shear and normal stresses in the weld. The exponent in the fracture law is optimised using the test results of KSII-30° and -60°. It is possible to model the coach-peel and KSII-0° tests, which were not used for parameter determination. But this is only possible for the laser welds in DC04. The same strategy leads to an overestimation of strength of nearly 100 % in the coach-peel simulation for TRIP700 laser welds because of the changes in fracture mode. To take this into account, a separate fracture criteria for bending is necessary and a material model for spot welds, *MAT_SPOTWELD_DAIMLERCHRYSLER, was used successfully taking energy absorption behaviour with the new option DG_TYP=3 into account. For the verification of the laser weld modelling component test are done using a so called T-specimen with four or six critical loaded laser welds depending on the loading direction. The simulations of the component tests with specimens made of DC04 have shown a good agreement with the test results using the cohesive material model for the simplified laser weld model. While simulating the TRIP700 component tests with the spot weld model the basic necessity of modelling the energy absorption was shown.

• Modelling of the deformation and fracture behaviour of laser welds for crash simulation

  Silke Sommer - Fraunhofer Institut Werkstoffmechanik IWM, Frederik Klokkers - Laboratorium für Werkstoff- und Fügetechnik LWF

  The light weight potential in automobile fabrication is increasing due to the development of new high strength steels. The realisation of this potential requires the use of adjusted joining techniques for the combination of optimized material properties with optimized joint properties. With the development of laser welding to a series-production technology a joining technique is available to practise the light weight potential of high strength steels. The advantages of laser welding compared to conventional welding techniques are the high process velocity, the low thermal influences of the material and the flexibility in joint figure and position [1, 2]. The flange width can be reduced that leads to weight reduction and design advantages. Softening in the heat affected zones beside the welds is avoided because of the compressed heat input during laser welding. The strength of the high strength steels remains in the joint. The application of laser welding is increasing for joining automotive components to the body in white [3]. But laser welding is less used compared to conventional joining techniques like spot welding. The reasons are the missing knowledge about crash worthiness of laser welds and missing methods to model the laser welds in crash simulation. The questions are how laser welds behave under crash loading: What are the experimental methods for a reliable characterisation? What are the numerical methods for an efficient simulation of the load-bearing capacity of the joints? A working group of FAT AK27UA crash and occupants simulation initiated a research project to answer these questions. Two different weld geometries of laser welded step welds were investigated. Those are short linear and c-shaped welds as single parts of the step welds. The investigations of the laser welded joints are done using two different steel kinds. First a low strength steel, DC04, with a tensile strength of about 300 MPa and second a high strength steel, TRIP700, with a tensile strength of about 670 MPa are used. The laser welding of the 1.5 mm and 2.0 mm thick steel sheets was done by Daimler Forschung in Ulm, Germany. Metallographic investigations of the welds were done. The welds were cutted and grinded and hardness profiles were measured over the weld. The average hardness was about 200 HV0.1 in the weld metal of DC04 linear welds compared to 100 HV0.1 in the base metal. The average hardness was about 470 HV0.1 in the weld metal of TRIP700 linear welds compared to 215 HV0.1 in the base metal. The width of the linear laser weld was about 1 mm and the length of the single linear laser weld was about 18 mm. Single welds were characterised using different specimen geometries to realise different loading situations like shear, tension, bending and combined shear-tension (KSII-0°,-30°,-60°,-90°, coach-peel and shear-tension specimens). For investigation of strain rate effects the loading velocity has been varied between quasi-static and 1.5 m/s. The load bearing capacity of the DC04 linear laser weld under shear-tension and KSII-0° are less (about 10 %) than under tension (KSII-90°) loading. The linear laser weld is shear loaded in weld direction with the KSII-0° specimen and perpendicular to the weld direction with the shear-tension specimen. In both shear loading cases the weld fails through interfacial fracture. In all other loading situations like KSII-90°,-30°,-60° and coach-peel the welds were buttoned out or peeled out of the connection. While investigating the linear welds in TRIP700 some changes in fracture mode occurred. Here, interfacial fracture occurred also in other loading situation especially under bending loading in the coach-peel specimen test. The scattering of load bearing capacity is higher as a result of the changes in fracture mode compared with the results in DC04 steel. For investigation of the local loading situation a detailed model with solid elements for the sheets and the weld is used containing different material zones for base metal, heat affected zone and weld metal. The result of this detailed simulations was, that the loading in the weld line is not homogeneous. For example under tension loading, KSII-90°, there are high normal stresses located in the base metal at the ends of the linear weld. The distribution of loading is also seen in a simplified model. Here the laser weld of 18 mm length is modelled using five connected solid elements. The metal sheets are modelled with shell elements, of course. The elastic-plastic material model *MAT_024 without failure strain is used for the shells. The cohesive material model *MAT_ARUP_ ADHESIVE is used for the solid elements of the laser weld defined here as cohesive elements. The fracture parameters of *MAT_ARUP_ADHESIVE are determined with simulation of shear-tension and KSII-90° tests taking into account the local distribution of shear and normal stresses in the weld. The exponent in the fracture law is optimised using the test results of KSII-30° and -60°. It is possible to model the coach-peel and KSII-0° tests, which were not used for parameter determination. But this is only possible for the laser welds in DC04. The same strategy leads to an overestimation of strength of nearly 100 % in the coach-peel simulation for TRIP700 laser welds because of the changes in fracture mode. To take this into account, a separate fracture criteria for bending is necessary and a material model for spot welds, *MAT_SPOTWELD_DAIMLERCHRYSLER, was used successfully taking energy absorption behaviour with the new option DG_TYP=3 into account. For the verification of the laser weld modelling component test are done using a so called T-specimen with four or six critical loaded laser welds depending on the loading direction. The simulations of the component tests with specimens made of DC04 have shown a good agreement with the test results using the cohesive material model for the simplified laser weld model. While simulating the TRIP700 component tests with the spot weld model the basic necessity of modelling the energy absorption was shown.

• Modelling of the dynamics of a 40 mm gun and ammunition system during firing

  N. Eches, D.Cosson - Nexter Munitions, Q. Lambert - C.T.A. International, A. Langlet - C.T.A. International / Université d’Orléans, J. Renard - Université d’Orléans

  This paper deals with the development of a finite element model of a 40 mm Case Telescoped Ammunition and its associated gun, able to describe the in-bore travel of the projectile during firing. This work is part of a PhD thesis, supervised by CTA International and the PRISME Institute, dedicated to the study of the parameters relevant to the accuracy of the Kinetic Energy Round. In order to conduct efficient parametric studies, they asked Nexter Munitions to take the lead for the finite element simulations of the in-bore travel, which is expected to be one of the most contributing phases of the firing event on the ammunition consistency. Nexter Munitions has set up a gun/ammunition model, applying the principles used for the same kind of work in 120 mm ([1] and [2]). The 40 mm study added some issues such as the progressive rifling of the gun, and the slipping obturator, which reduces the projectile spin rate. The model is compared to actual firing carried out by CTAI, through the strains measured on strain gages lying on the barrel and on an instrumented penetrator, ftted with an on-board data recorder. i The paper focuses on the correlation between the strain gages measurements and the simulation of the exact test configuration. It was necessary to run several configurations, with different contact logic and friction coefficients to match simulation and experiment.

• Modelling of the dynamics of a 40 mm gun and ammunition system during firing

  N. Eches, D.Cosson - Nexter Munitions, Q. Lambert - C.T.A. International, A. Langlet - C.T.A. International / Université d’Orléans, J. Renard - Université d’Orléans

  This paper deals with the development of a finite element model of a 40 mm Case Telescoped Ammunition and its associated gun, able to describe the in-bore travel of the projectile during firing. This work is part of a PhD thesis, supervised by CTA International and the PRISME Institute, dedicated to the study of the parameters relevant to the accuracy of the Kinetic Energy Round. In order to conduct efficient parametric studies, they asked Nexter Munitions to take the lead for the finite element simulations of the in-bore travel, which is expected to be one of the most contributing phases of the firing event on the ammunition consistency. Nexter Munitions has set up a gun/ammunition model, applying the principles used for the same kind of work in 120 mm ([1] and [2]). The 40 mm study added some issues such as the progressive rifling of the gun, and the slipping obturator, which reduces the projectile spin rate. The model is compared to actual firing carried out by CTAI, through the strains measured on strain gages lying on the barrel and on an instrumented penetrator, ftted with an on-board data recorder. i The paper focuses on the correlation between the strain gages measurements and the simulation of the exact test configuration. It was necessary to run several configurations, with different contact logic and friction coefficients to match simulation and experiment.

• Modelling of the failure behaviour of windscreens and component tests

  D.-Z. Sun, F. Andrieux, A. Ockewitz Fraunhofer Institute for Mechanics of Materials, H. Klamser, J. Hogenmüller - Dr. Ing. h.c. F. Porsche AG

  Windscreens from laminated safety glass (glass/PVB interlayer/glass) are widely used in automotive structures and have an important contribution to the stiffness of the vehicle. The stiffness of the laminated safety glass is dominantly given by the two layers of glass while the PVB interlayer serves to fix glass splinters to avoid serious injuries of the passengers in a collision. A finite element model for modelling the failure behaviour of laminated glass windscreens is presented. A special element structure with three layers (shell/volume/shell) has been used to model the laminated glass windscreen. A fracture criterion for brittle fracture based on the maximum principal stress (σI ≥ σc) was applied to model the fracture behaviour of glass. The PVB interlayer was modelled with both a linear elastic and a hyperelastic material law without damage. The critical fracture stress of glass was determined by fitting the failure force measured from static bending tests on laminated glass windscreens. The transferability of the fracture criterion and the corresponding parameter was checked by simulating two different loading cases of the component tests.

• Modelling of the Overcasting Reinforcement Process using the LS-DYNA ICFD Solver

  J. Burt, O. Tomlin (GRM Consulting), D. Howson, T. Fleet (Alvant)

  The overcasting reinforcement process is a complex casting technique for creating lightweight aluminum components with additional strength from an aluminum matrix composite (AMC) insert. Empirical work to date has shown there are opportunities to further enhance the quality of adhesion between this AMC insert and cast aluminum. It is also evident that developing a predictive tool of bond quality will reduce the need for invasive measuring techniques.

• Modelling of Thermo-Viscoplastic Material Behavior Coupled with Nonlocal Ductile Damage

  M. Nahrmann, Prof. A. Matzenmiller (University of Kassel)

  The postcritical behaviour due to mechanical loading of the high strength steel HX340LAD (ZStE340), typically used for cold forming of complex structures is modelled by means of a yield curve in the softening part of the material. Due to local heating, caused by viscoplastic deformations particularly for high strain rates, a thermo-mechanical coupled simulation is carried out by taking into account the conversion of plastic work into heat. Moreover, a temperature and rate dependent material model, coupled with ductile damage, is applied to allow the prediction of damage and failure of metal components caused by large plastic deformations during forging or sheet metal forming. The constitutive equations are implemented as a user defined material model into LS-DYNA and include the temperature dependency of the material parameters such as for the YOUNG's modulus, the initial yield stress, the nonlinear isotropic hardening parameter, the strain rate sensitivity as well as for the moduli of a continuum damage mechanics based approach. The nonlocal damage option *MAT_NONLOCAL in LS-DYNA is used to prevent localisation of the damaged zone for small elements. Test data of tensile specimens are considered under different strain rates from 0.006 1/s (quasistatic) up to 100 1/s for identifying the model parameters with the optimisation software LS-OPT. Finally, the numerically predicted stress-strain curves are compared to the according test data for the model verification. In addition, the computed heat evolution due to plastic flow is compared to the experimental measured data in terms of time-temperature courses. Finally, the plastic necking of the tensile specimen is investigated by means of the spatial strain distribution.

• Modelling Spotweld Fracture Using CrachFEM

  D. P. Norman (TATA Steel UK Limited)

  In recent years, a number of research institutes have concentrated on trying to develop fracture models that are generally applicable to a wide range of engineering problems. Examples of some of these fracture models are from Gurson and various extensions to Gurson[1], Dell and Gese (CrachFEM)[2], Xue-Wierzbicki[3], Wilkins (EWK model)[4], and du Bois (*MAT_GISSMO)[5]. The key features of these models are a dependency of the fracture strain on the stress triaxiality and a means of accounting for void growth or instability due to necking. Some of these models also incorporate non-linear strain accumulation, kinematic hardening and sophisticated plasticity models, which may be necessary for modelling certain types of materials. The Dell and Gese (CrachFEM) material model is a popular choice in the European automotive industry and has been used in this study. One of the application areas of concern is at or near to spot welds, where the material properties of the weld and Heat Affected Zone (HAZ) are very different to the sheet and fracture predictions can be signicantly affected by this. This work investigates the potential for developing an accurate 3D weld model to describe the lap shear and cross tension plug fracture modes observed in DP600. Obtaining stress strain curves for the weld nugget and HAZ is a challenge. The standard approach is to use heat treated test coupons to perform a range of non-standard material coupon tests, with test coupons having the same micro-structures as the weld nugget and HAZ. To prepare the heat treated test samples requires spot welding simulation to determine the required temperature time curves observed during spot welding followed by Gleeble testing to reproduce the required temperature time cycles on test coupons. This is difficult to achieve in practice and several iterations may be needed to achieve the required micro-structures. This set of tasks is a significant undertaking and has been the subject of a number of university PhD and post-doctorate research studies. Dancette [6] and Sommer [7] are very good examples of this research. In this study, a simplified approach has been adopted using weld micrographs and micro-hardness indentation tests to infer the geometry and stress strain properties and to assume the fracture properties are the same as the sheet. This approach lacks the rigour of material testing coupons with tailored heat treatments but does provide a simpler approach that can be implemented more easily in industry.

• Modelling Study to Validate Finite Element Simulation of Railway Vehicle Behaviour in Collisions

  X. Xue - AEA Technology Rail, F. Schmid - University of Sheffield

  Half-width/full-length and half-width/half-length vehicle models, based on geometrical symmetries, have been adopted widely in the finite element modelling of rolling stock structural behaviour. These techniques have been successful in the analysis of rail vehicles undergoing static loading, such as the proof load test, and in basic impact studies. Until now, such rail vehicle impact tests and associated simulations have been largely confined to impact scenarios where a rail vehicle collides with a rigid wall or a rigid body. This is also a standard model specified in the crashworthiness section of the Technical Standards for Interoperability. The authors identified a need to study the limitations of these impact scenarios and modelling techniques when applied to dynamic impacts. The authors of the paper present the results of studies focusing on the above areas. The work was carried out by means of finite element analysis and comparison. The train set studied is a conventionally designed high-speed electric multiple unit. Finite element models of full vehicle structures were used in all impact scenarios. It was found that impact modelling could mask some structural weaknesses when using a rigid wall as the impacted object. A symmetrical impact was shown to lead to an unsymmetrical result and, therefore, both half and quarter structure models may hide some aspects of crash behaviour. These findings have significance for both impact simulation and the physical testing of rail vehicles.

• Modelling the dynamic magneto-thermomechanical behaviour of materials using a multi-phase EOS.

  Le Blanc Gaël, Jacques Petit, Pierre-Yves Chanal - Centre d’Etudes de Gramat, L’Eplattenier Pierre - LSTC, Livermore, Avrillaud Gilles - ITHPP

  For several years the “Centre d’Etudes de Gramat (CEG)” has been studying the behaviour of materials by means of experimental devices using High Pulsed Powers technologies. Among them, GEPI is a pulsed power generator devoted to ramp wave (quasi isentropic) compression experiment in the 1 GPa to 100 GPa pressure range. It may also produce non shocked high velocity flyer plates in the 0.1 km/s to 10 km/s range of velocity. The basic principle is based on a strong current circulation into electrodes. This current generates within the electrode a magnetic pressure wave (several GPa via the Laplace forces) and a strong rise of the temperature (several thousands K) due to Joule effect. Depending on that temperature, materials may be locally subjected to phase transitions such as solid to liquid or liquid to vapor. Modelling a GEPI shot requires an Electromagnetism/Mechanical/Thermal 3D solver to study all the physical phenomena. CEG has selected LS-DYNA because a new electromagnetism solver is coupled to the historical solvers (mechanical and thermal) in LS-DYNA beta version 980. However, there is, at the moment, no equation of state with phase transitions available in LS-DYNA standard version. It is for this reason that the GRAY multi-phases EOS, developed at LLNL, is implemented as a user subroutine in LS-DYNA. The GRAY EOS allows taking into account phase transitions thanks to energies threshold. In this paper, the GEPI device is briefly described as well as the LS-DYNA EMAG solver. The GRAY EOS is described and its implementation is discussed. Examples of applications are presented, in particular, the modelling of a GEPI experiment involving local liquefaction of the electrodes. The numerical free surface velocities are compared to experimental measurements. The liquefaction process is analyzed and compared to post-mortem observation on the electrodes. To conclude, the model limitations and potential improvements are presented.

• Modelling the dynamic magneto-thermomechanical behaviour of materials using a multi-phase EOS.

  Le Blanc Gaël, Jacques Petit, Pierre-Yves Chanal - Centre d’Etudes de Gramat, L’Eplattenier Pierre - LSTC, Livermore, Avrillaud Gilles - ITHPP

  For several years the “Centre d’Etudes de Gramat (CEG)” has been studying the behaviour of materials by means of experimental devices using High Pulsed Powers technologies. Among them, GEPI is a pulsed power generator devoted to ramp wave (quasi isentropic) compression experiment in the 1 GPa to 100 GPa pressure range. It may also produce non shocked high velocity flyer plates in the 0.1 km/s to 10 km/s range of velocity. The basic principle is based on a strong current circulation into electrodes. This current generates within the electrode a magnetic pressure wave (several GPa via the Laplace forces) and a strong rise of the temperature (several thousands K) due to Joule effect. Depending on that temperature, materials may be locally subjected to phase transitions such as solid to liquid or liquid to vapor. Modelling a GEPI shot requires an Electromagnetism/Mechanical/Thermal 3D solver to study all the physical phenomena. CEG has selected LS-DYNA because a new electromagnetism solver is coupled to the historical solvers (mechanical and thermal) in LS-DYNA beta version 980. However, there is, at the moment, no equation of state with phase transitions available in LS-DYNA standard version. It is for this reason that the GRAY multi-phases EOS, developed at LLNL, is implemented as a user subroutine in LS-DYNA. The GRAY EOS allows taking into account phase transitions thanks to energies threshold. In this paper, the GEPI device is briefly described as well as the LS-DYNA EMAG solver. The GRAY EOS is described and its implementation is discussed. Examples of applications are presented, in particular, the modelling of a GEPI experiment involving local liquefaction of the electrodes. The numerical free surface velocities are compared to experimental measurements. The liquefaction process is analyzed and compared to post-mortem observation on the electrodes. To conclude, the model limitations and potential improvements are presented.

• Modelling the Dynamics of Well Perforation

  Marco Serra, John P. Rodgers

  One of the crucial steps in the completion of many oil wells is their perforation, required to establish communication with the target reservoir. Perforation is a very short duration, high energy event in which a series of explosive shaped charges is fired to produce corresponding perforations into the hydrocarbon-bearing formation. This event gives rise to violent pressure and structural dynamics that die out within a second or two, depending on the specific completion design. During this time, the nature of the pressure dynamics and resulting fluid response determine the initial quality of the communication between the well and the formation, which has significant consequences for the overall productivity over the well’s lifetime, as well as the integrity of the tool string components during the perforation event.

• MODELLING THE SHAKEN BABY SYNDROME

  I.C. Howard, E.A. Patterson, J. Langley - University of Sheffield (SIRIUS)

  Physical child abuse is common. For the UK alone, an informed estimate is that every year more than 200 infants die from brain injuries inflicted by violent shaking (“Shaken Baby Syndrome”). Around twice this number, who actually survive such treatment, are left with severe mental and physical disability including blindness due to associated damage to the retina (the light-sensitive part of the eye). Although it is now distressingly obvious that shaking often causes debilitating brain and eye injuries, it is unclear how it happens, whilst such combined injuries are rare even in severe accidental head trauma with skull fractures. The work involves the use of LS-DYNA to explore some of the mechanical fundamentals of these phenomena. Specifically, it addresses the difference between motions induced in the brain through the “single event” loading that is normally associated with impacts and those induced by shaking. The paper also describes a set of experiments that measured the accelerations induced by shaking an automotive dummy of a 9-month old child. The “shakers” included young men and women, and middle-aged men and women. They also ranged between small and delicate, and large and muscular. The data from this sort of experiment is essential input to the DYNA simulations.

• Modelling thick-walled aluminium extrusions in side- crash applications

  E. Teixidó-Marquès, D. Morin, O.S. Hopperstad, T. Berstad, B. Olsson, M. Costas

  In this study, the numerical modelling of a thick-walled aluminium extrusion which serves as a protective structure for battery trays in electric vehicles was studied. The thick-walled profile was modelled in a pole-crushing test. For this application, four aluminium alloys of different strength were considered: AA6063, AA6082, AA6005 air-cooled and AA6005 water-cooled. Shell elements proved to be inadequate in accurately describing the mechanical behaviour of thick-walled extrusions. Differences in the deformation mode and the computed force were observed between shell and solid models. Parametric studies were performed to evaluate the effect of fracture model, element formulation, contact formulation, and friction coefficient.

• Models for strain path independent necking prediction in LS-DYNA

  Kjell Mattiasson (Chalmers University of Technology, Volvo Cars Safety Centre) , Johan Jergeus (Volvo Cars Safety Centre), Paul Dubois (Hermes Engineering NV)

  Failure in sheet metal can be caused by one of, or a combination of, the following mechanisms: ductille fracture, shear fracture and plastic instability (necking). Ductile fracture is causrd by the initiation, growth and coalescence of voids in the material during plastic straining, commonly referred to as damage growth. Micro defects can also lead to through-thickness shear fracture in the sheet metal. There are several difIerent scenarios involving the a_ove mechanisms leading to material fracture. In ductile materials fracture is normally preceded by the formation of a neck in which the strains localizes after further loading. This neck has the width of the order of the sheet thickness. After the initiation of the neck the strains and the damage inside the neck start to grow rapidly. and finally the material breaks accoding to one of the mechanisms described above. The incipient necking is in this case also referred to as "plastic instability" as the phenomenon is solely dependent on the plastic properties of the material. It should be observed that the incipient necking phenomenon can be captured by a plane stress shell FE model if the elements are small enough, i.e. of the order of the sheet thickness. After the formation of the neck the stress state in the neck turns into a 3D one, and a highly refined 3D FE- model is rEquired to be able to simulate the post-necking behaviour. Another possible scenario is that damage starts to grow before the formation of a neck. The softening of the material can than speed up the neck formation. In some less ductile materials, e.g. some aluminium alloys and austenitic stainless steels, crack formation can even take place before strain Iocalization. Experience has, however, revealed that incipient necking is the by far the most common failure mode in sheet metal forming applications, as well as in automotive crash applications. The current paper will therefore be focused on the prediction of necking, and especially on methods for handling the strong strain path dependence of this phenomenon. The LS-DYNA code is used by Volvo Can for pertorming car crash simulations. Currently the third- party module CrachFEM from the MaHem company, which is linked to the LS-DYNA code. is used for performing material failure analmes. However. Iately several models for perIorming necking as well as fracture simulations have been implemented in LS-DYNA. It is the object of the current paper to give an overview of these options and to present results from some evaluations of these models.

• Modern Field Code Cluster of Fluid Dynamics and Structure Mechanics with MetaComputing Grids for Safety and Environment Research Studies

  W. Rehm, B.Wang - Forschungszentrum Jülich, B. Binninger - University Aachen, C. Nae - University Bucharest

  In this this paper, we describe main results obtained within the scope of joint project activities concerning the numerical simulation of reacting flows in complex geometries. The aim is the refinement of numerical methods for applied computational fluid dynamics (CFD) using high-performance computations (HPC) to study explosion processes in more detail, especially for hydrogen safety and environment aspects of innovative technical systems. The R&D work is mainly focused on the modelling of the accident-related behaviour of hydrogen in safety enclosures ranging from slow to fast or even rapid flames with resluting explosion loads. Therefore, we have established a modern field code cluster with supercomputing and special modules for specific studies, including fluid-structure responce This recent methodology allows the assessment of adequate safety measures to control deflagration-to-detonation transition (DDT) processes and to suppress fires or explosions with relevance to industrial safety, to reduce combustion loads and structural deformations. For instance, visualization/animation of flow and crash tests are presented.

• Modified Dynamic Time Warping for Utilizing Partial Curve Data to Calibrate Material Models

  Katharina Witowski (DYNAmore GmbH), Nielen Stander (Livermore Software Technology, Livermore)

  Material calibration can be solved as a non-linear regression problem in which a parametric model of the material test is calibrated to its experimental result. In typical material testing, temporal and/or spatial data is produced experimentally and compared to its computational equivalent. At its basic level a single response comparison consists of two curves which are matched to produce a distance between them. The calibration requires minimizing the distance measure. The difficulty of the comparison is determined by phenomena such as noise, hysteresis and differences in geometric curve length (length compatibility). While noise and hysteresis problems have been solved in this context using LS-OPT® in the distant past, the question of curves having substantially different lengths has remained a challenge until recently. In one example, the computational output extracted from LS-DYNA® causes parts of the output to not be relevant to the test data. In this case most distance measures produce spurious distance calculations. This paper introduces a method to address this question. The approach is based on a modification of the Dynamic Time Warping distance measure and referred to as Modified Dynamic Time Warping or DTW-p (for partial). It consists of the trimming of the DTW path as well as iterative mapping to produce a uniform map. An example based on output of the GISSMO model in LS-DYNA is used to demonstrate the effectiveness of the method.

• Modular Strategy To Build Full Vehicle Finite Element Mode

  Subrato Dhar, William E. Hohnstadt, Jeffrey D. Green - General Motor Corporation

  The modular approach developed is a unique methodology for building a full vehicle finite element model which allows the use of a single vehicle model, assembled using component modules, to simulate multiple test configurations. This concept allows multiple users to efficiently contribute to construction of a model that can be used to run any number of test configurations. The benefits of a modular approach to full-vehicle finite element model were demonstrated by the C/K (full size truck) product line. While some configuration must be validated using physical tests, these tests can also be used to correlate a finite element model. Perturbation of the model can then be used to evaluate similar configurations and increase confidence in the design, without requiring additional hardware. This modular process can be implemented on all platforms as well, but with lesser savings for less complex products.

• Module Development of Multiphase and Chemically Reacting Flow in LS-DYNA® Compressible Flow Solver

  Kyoung-Su Im, Zeng-Chan Zhang, Grant Cook, Jr. - Livermore Software Technology Corp.

  We reported a significant progress of the simulation module developments such as the cavitation, supersonic heterogeneous combustion, and gaseous detonations for the compressible flow solver. The homogeneous equilibrium model (HEM) based on the acoustic speed of the mixture of liquid and vapor was implemented for automotive diesel injectors, where the cavitation effects should correctly predict for the nozzle design. The heterogeneous combustion based on an Eulerian-Lagrangian model was developed for thermobaric explosive (TBX) applications in which a stochastic particle technique in conjunction with a probability density function (PDF) is adopted. In modeling of gaseous detonation, we implemented various combustion modules depending on the reaction model: one-step reaction (ZND model), reduced reaction of intrinsic low-dimensional manifolds (ILDM), and detailed chemistry model. Application results validated with experimental data are demonstrated with detailed discussion.

• Monopile damage assessment from impact with a sub-sea boulder, using an LS-DYNA methodology

  David McLennan, Francesca Palmieri, Andrew Cunningham, James Go, Richard Sturt, Paul Morrison, César Tejada, Georgios Perikleous, Jacob Brandt, Mikkel Lubek

  During the installation of monopiles (MP) for the offshore wind turbine industry, there is a site-specific risk of impact with submerged sub-sea boulders, depending on the nature of the site geology. Factors such as boulder size, boulder depth, soil properties, and impact angle, will influence the level of damage experienced by the MP due to the boulder impact.

• More Realistic Virtual Prototypes by means of Process Chain Optimisation

  Peter Gantner, Herbert Bauer - Aalen University, David K. Harrison, Anjali K. M. De Silva - Glasgow Caledonian University

  This paper is concerned with closing a gap in the process chain of metal forming. Tools for simulating the metal forming process like LS-DYNA® produce output geometries and stress information which cannot be easily re-imported in CADSystems or structure analysis programs for further processing. A concept has been developed and implemented with a corresponding program which allows the re-importation of parts with certain topologies (tube, plane) from LSDYNA® into any STEP-conformant CAD program. This method is mainly based on using the interconnection information which is contained in the LS-DYNA® output file. This information allows the construction of interpolating cubic B-Spline surfaces which can be represented in the STEP standard format. Thus, it is not necessary to reinvent general purpose surface reconstruction programs but rather to harvest the additional information available in the given situation. Furthermore, a method to make the strength hardening information available in structure analysis is represented. This hardening results from the forming process and should be considered to obtain a more realistic virtual prototype and is of assistance to save weight and material costs. Introduction The forming simulation by means of finite element analysis (FEA) is becoming more and more important in the field of process quality assurance and process design of mechanical and fluid media formed components. Using the finite element simulation in the development process of hydroforming components from the first draft through to the serial production of a component provides an enormous saving of development time and costs. However, due to the constantly increasing competition in terms of costs, development time and quality, a further reduction of processing time and costs is necessary. Moreover, there is the demand for even more exact predictions and results in the area of the virtual component, in order to reduce the weight and to ensure that the component produced will have enough stability and low material costs. Due to this demand the integration of the forming simulation into the process chain must be improved. In order to point out the optimisation potential, the sequence of the processes from the design phase to the finished component is represented in Figure 1.

• More than 40% cost reduction through drop test simulation with Ansys LS-DYNA

  Manfred Maurer, Alain Capt, Yury Novozhilov

  The cost-sensitive development project for a new sewing machine series within Bernina International AG includes optimizing the packaging to the new logistical conditions and adapting it to the new product design. Packaging protection also had to be increased. Regarding specifications, no acceleration forces more significant than 100G may occur on the machine during a standardized drop test from a height of 0.9m. Furthermore, polystyrene should be reduced by at least 20% for cost and environmental reasons. For the end customer, the package should be easy to transport by hand and leave a tidy and logical impression when unpacked, which was difficult to specify and led to some loose ends concerning the arrangement of accessories.

• Mortar Contact Algorithm for Implicit Stamping Analyses in LS-DYNA

  Thomas Borrvall - Engineering Research Nordic AB, Sweden

  A challenging task for the static implicit nonlinear solver in LS-DYNA is to accurately and robustly solve contact problems, especially is this needed for stamping simulations. This paper aims at investigating the benefits of a mortar segment-to-segment contact algorithm by Puso and Laursen [1,2] when compared to the traditional node-to- segment approach. A penalty based version of the algorithm is implemented in LS-DYNA, meaning that the contact tractions are proportional to both the penetration as well as the overlapped area of segments in contact. This allows for the nice property that the resulting global contact force is continuous with respect to deformation and thus makes the approach intuitively suitable for implicit analyses. Further measures for smoothing the response are implemented in the method and the first tests indicate that the method is advantageous at least for a certain class of problems, but how great the overall impact will be remains to be seen.

• Moving Beyond the Finite Elements: A Comparison between Finite Element Methods and Meshless Methods for Modeling Honeycomb Materials and Simulating Side Impact Moving Deformable Barriers

  Murat Buyuk,Shaun Kildare,Cing-Dao (Steve) Kan - The George Washington University

  Movable Deformable Barriers (MDBs) are used in surrogate tests to represent the behavior of an average midsize vehicle. The main difficulty in MDB modeling is the prediction of frontal energy absorbing barrier, where honeycomb materials are used and usually expected to simulate complex failure modes. In side impact tests, the severe shear deformation of the honeycomb material, full densification of barrier edge, rupture of aluminum cover sheets, and tearing of honeycomb blocks are often observed. This complex pattern of honeycomb material failure mode makes it difficult to predict. Numerical instabilities, such as negative volume, severe hourglassing, and inaccurate predictions are often experienced. In this study, National Highway Transportation Safety Administration (NHTSA) side impact MDB is modeled by using a 3D non-linear explicit dynamics numerical solver, LS-DYNA. As a conventional modeling technique, both barriers are first modeled by using Lagrangian solid hexahedron finite elements (FEs). Mat-26 (*MAT_HONEYCOMB) is used as a constitutive model for the barrier construction. By using this Lagrangian model as a reference point, Eulerian and Arbitrary-Lagrangian Eulerian (ALE) models of the MDBs are also created. However, when the distortions become very severe, especially Lagrangian FE algorithms are not always adequate. Honeycomb material behavior is found to behave unstable in this type of impact problems. More recently meshless methods (or particle methods) have been developed and applied to solid mechanics problems since they can efficiently be used to represent severe distortions. In this study, Element Free Galarkin (EFG) model of the MDB is also created. Each MDB model is compared to a full scale crash test against a load cell wall. Accelerometer responses from the simulations are compared to the measured values from the test. Computational costs of the systems are also compared to provide a foresight for the usage of the meshless methods in transportation safety field related research. Dhafer Marzougui, FHWA/NHTSA National Crash Analysis Center, The George Washington University

• Moving Beyond the Finite Elements, a Comparison Between the Finite Element Methods and Meshless Methods for a Ballistic Impact Simulation

  Murat Buyuk, Cing-Dao Steve Kan, Nabih E. Bedewi - The George Washington University, Ali Durmus, Sedat Ulku - Uludag University

  For the past several decades, finite element techniques have been used extensively for the analysis of computational solid mechanics problems. However, when the distortions become very severe, especially Lagrangian finite element algorithms are not always adequate. More recently meshless methods (or particle methods) have been developed and applied to solid mechanics problems since they can efficiently be used to represent severe distortions and are more robust for dynamics problems such as high energy impacts and penetrations that involve large deformations and even erosions. Impacts at higher speeds are also challenging because of the high strain rate behavior of the materials and the significant importance of the stress wave propagation through the material. In this paper, the deformation pattern and characteristics of a thin (50 μm) foil is investigated both numerically and experimentally under impact loading of a 9 mm standard NATO bullet, at several speeds by using a 3D non-linear explicit numerical code, LS-DYNA. Different element and particle algorithms are used to obtain the best numerical representation of the problem. The differences between Lagrangian, Eulerian, ALE (Arbitrary Lagrangian- Eulerian) and SPH (Smoothed Particle Hydrodynamics) formulations are briefly compared and discussed under ballistic impact conditions. The results obtained from these different numerical models are also validated with a series of tests and are in good agreement with the experimentally measured values.

• MPDB Pre- and Postprocessing in Generator4 and Animator4

  Leyre Benito Cia, Christian Mospak, Christoph Kaulich (GNS mbH)

  While the development of modern cars reduces the risk of injuries for the occupants in a lot of different load cases which are well-defined for different scenarios, the risk to get injured when hitting another car with a partial overlap between the two vehicles is still high. The structure of the two involved cars is not able to completely absorb the energy from the occupants. Around 2010, a new type of barrier and test procedures were developed in order to simulate this type of accident. A moving honeycomb barrier hitting a driving car with an offset, should help improving modern cars. This test is used as procedure for different NCAP organizations around the world from 2020. Generator4 and Animator4, the FEA pre- and postprocessors from GNS mbH, can help the engineer to set up, start and evaluate simulations of MPDB barriers, calculating the loads on the occupants and the deformations in the barrier.

• MPI Optimizations via MXM and FCA for Maximum Performance on LS-DYNA

  G. Shainer, T. Liu, P. Lui, T. Wilde (Mellanox Technologies)

  From concept to engineering, and from design to test and manufacturing, the automotive industr y relies on powerful virtual development solutions. CFD and crash simulations are performed in an effort to secure quality and accelerate the development process. The recent trends in cluster environments, such as multi-core CPUs, GPUs, cluster file systems and new interconnect speeds and offloading capabilities are changing the dynamics of clustered- based simulations. Software applications are being reshaped for higher parallelism and hardware configuration for solving the new emerging bottlenecks, in order to maintain high scalability and efficiency. In this paper we cover a new co-design architecture with hardware based accelerations and offloads for MPI collectives communications and how it affects LS-DYNA performance.

• MPP Contact: Options and Recommendations

  B. Wainscott (LSTC)

  There are many different contact algorithms currently implemented in LS-DYNA, each having various options and parameters. I will discuss only a few of them. Much of what is covered will only apply to the MPP version of LS-DYNA. I will start with some general background information, and then give details about some of the more interesting recent options that you might find useful.

• MPP DECOMPOSITION OF A SPH MODEL

  Jean Luc Lacome - LSTC Vincent Lapoujade Cril Technology – Groupe Alyotech

  SPH, Smoothed Particle Hydrodynamics, is a very efficient tool to model industrial problems where large deformations occur. However, one disadvantage of the SPH technique is the expensive cpu cost compared to standard Finite Elements. Using the MPP version of LS-DYNA allows users to handle large problems (more than a million of particles) in a reasonable time. Due to the meshfree nature of the SPH method, standard decompositions used for finite elements can sometimes lead to very bad speed-up of the code. Users have to be aware of some options and rules to define customized decompositions in order to minimize communications between processors and get very good load balancing. Two different models are presented. The first one is a pure SPH model of a high velocity impact of a sphere on a plate, the second one is a coupled FE-SPH model of a bird impacting a set of fan blades of an engine.

• MPP Execution of Implicit Mechanics with 10M or More Elements

  Dr. C. Cleve Ashcraft, Roger G. Grimes, and Dr. Robert F. Lucas - LSTC

  LS-DYNA models for Implicit Mechanics are getting larger and more complex. We are continually seeing models where the linear algebra problems in Implicit Mechanics have 3 to 5 million elements and know of at least one that is nearly 30M elements. It is these very large linear algebra problems that distinguish the computer requirements for Implicit Mechanics. This paper will present a study of the performance of the MPP implementation of implicit mechanics in LS-DYNA examining such issues as performance, speed-up, and requirements for computer configuration.

• MPP Implicit for LS-DYNA v. 971

  Cleve Ashcraft, Roger Grimes, Bob Lucas - LSTC

  The Vision • LSTC wants to provide a single package that allows users to perform all of their analyses. – Implicit computations must be integrated with explicit – Linear analyses (useful for debugging large models) must be integrated as well.

• MPP in Stamping Simulations with LS-DYNA

  Kaiping Li, Yang Hu - DaimlerChrysler Corporation

  With the continuous improvement of MPI protocols, for example, Lam-MPI, MPICH, etc.., even fast computer hardware and network connections, the applications of MPP technologies in multi-stage stamping simulations for auto industries becomes more and more attractive, not only because of their scalability, but also for their ability to re-use the older equipments without sacrifice the speed of simulations. In this paper, we will present our study results on the MPP version of LS-DYNA in our stamping simulations and our ultimate goal with this technology. Nowadays, in order to reduce operation costs and maintain high quality of products, FEA simulations of stamping processes become de-facto in the auto industries. With the continuous improvement of FEA technology and computer hardware, numerical simulations of multi-stage stamping operations have become a reality. Because the deliverability of simulations is one of our five major quality measurements, we need even faster simulation speed to catch up with new product style changes.

• Mullins Effect in Rubber Part Two: Biaxial

  William W. Feng, John O. Hallquist (Livermore Software Technology Corp.)

  The formulation, testing and numerical study of the Mullins effect on rubber are presented. To demonstrate the Mullins effect experimentally, a biaxial test, inflation of a plane circular membrane, is used. Some experimental test data are shown. An approximate solution, a relation between the inflation pressure and the displacement at the center for the inflation of a plane circular membrane is presented. The test data and the approximate solution are used to determine the Mullins damage material constants. These constitution equations are implanted in LS-DYNA. The numerical results from LS-DYNA and analytical results are shown. They agree with one another.

• Multi Material Modeling with ANSA: An Application in the Automated Assembly Process in FORD

  T. Fokylidis, V. Karatsis (BETA CAE Systems), U. Tunc, H. Wuestner (Ford-Werke), N. Pasligh (Ford Forschungszentrum Aachen), C. Ping, M. Ng (Ford Australia)

  The simulations of virtual models hold a key role during the design process of a vehicle. The numerus different components in a CAE model make its assembly one of the most demanding tasks during the model buildup. Over the last years, the effort to achieve higher accuracy in crash test simulations has resulted in more detailed models. As a result, the FE representations used to connect the different parts vary a lot and get complex sometimes. To support effectively such time-consuming and error-prone modeling processes, the available tools should offer increased automation and standardization levels. A commonly used method is to simulate the area of these connections by using different material properties representing effectively not only the material of the connecting flanges but also the heat affected zones in each flange. Ford-Werke GmbH in cooperation with BETA CAE Systems has come up with a fully automated process within ANSA pre-processor that reads the CAE and its connection file, assigning the proper connectivity to each connection. Additionally, with the use of external files assigns the needed materials in the area of each spotweld using the respective LS-DYNA keywords. Finally reports to the user the results of the assembly procedure and the final status of each connection. The current paper explains the basic terms of the automated process mentioned above. Moreover, it presents the techniques used within ANSA to assembly a full analysis model in a fast and robust way combining different FE-representations and multi material assignment in the area of a connection.

• Multi Objective Optimization Approach for Biomedical Stent using Parametric Optimization

  M. Seulin (DynaS+), P. Balu (DEP)

  Stent deployment process and its long-term usage requires to meet multiple objectives like final stent diameters for cardiovascular disease treatments, and minimalistic plastic strain during the deployment to meet the fatigue life. Achieving an exact dilation diameter and maintaining minimal plastic strain values are mainly based on stent geometric design, cross section, material, amount of crimping and expansion diameter. This paper presents an effective stent finite element (FE) modelling and parametric optimization method using DEP MeshWorks stent rolling and parametric tools, LS-DYNA and LS-OPT optimization tools. Controllable design and deployment process parameters are considered for optimum random sampling using a Design of Experiments (DOE) approach, and using a parametric tool, designs are generated, on which analysis and optimization is performed using LS-DYNA explicit solver. The result is an optimum design solution which meets the required diameter criteria, without exceeding the minimal plastic strain limit, and within the foreshortening and flexibility limits.

• Multi-body Dynamic Simulation of Acti-Valve

  Cunjiang Cheng, GEO Widera - Marquette University, Michael Fassett - Acti-Valve Inc.

  A computer simulation of a valve (Acti-Valve) is generated using LS-DYNA. Fluid-structure interaction is considered in the finite element analysis (FEA). The stress, displacement and pressure distributions are analyzed during the opening movement of the valve under 1000 psi line pressure.

• Multi-Disciplinary Design Optimization exploiting the efficiency of ANSA-LSOPT-META coupling

  Korbetis Georgios, Siskos Dimitrios - BETA CAE Systems S.A

  Simple optimization techniques may serve well for the improvement of product performance at early concept design phases. At final phases though, optimization problems become more complex, with many variables and multiple optimum solutions. This leads to the need for the deployment of multi- disciplinary optimization techniques where many different load cases and analysis types, such as for Crash, NVH, CFD etc., are combined to achieve the optimum solution. The combination of ANSA CAE pre-processor, LS-OPT and mETA post-processor, offers an efficient and reliable tool for solving multi- disciplinary optimization problems. In such a process, starting from a common initial model, multiple outputs for different load cases and disciplines can be defined in ANSA. Design Variables that handle model shape and parameters are controlled in a centralized manner by the dedicated Optimization Task tool that is integrated in the core ANSA functionality. Further more, the newly released coupling between LS-OPT and mETA, provides a valuable tool for the definition of multi-disciplinary optimization scenarios, as mETA is able to extract responses from numerous solvers and load cases and feed them to LS-OPT.

• Multi-Disciplinary Design Optimization exploiting the efficiency of ANSA-LSOPT-META coupling

  Korbetis Georgios, Siskos Dimitrios - BETA CAE Systems S.A

  Simple optimization techniques may serve well for the improvement of product performance at early concept design phases. At final phases though, optimization problems become more complex, with many variables and multiple optimum solutions. This leads to the need for the deployment of multi- disciplinary optimization techniques where many different load cases and analysis types, such as for Crash, NVH, CFD etc., are combined to achieve the optimum solution. The combination of ANSA CAE pre-processor, LS-OPT and mETA post-processor, offers an efficient and reliable tool for solving multi- disciplinary optimization problems. In such a process, starting from a common initial model, multiple outputs for different load cases and disciplines can be defined in ANSA. Design Variables that handle model shape and parameters are controlled in a centralized manner by the dedicated Optimization Task tool that is integrated in the core ANSA functionality. Further more, the newly released coupling between LS-OPT and mETA, provides a valuable tool for the definition of multi-disciplinary optimization scenarios, as mETA is able to extract responses from numerous solvers and load cases and feed them to LS-OPT.

• Multi-Disciplinary Design Optimization for Occupant Safety: Leveraging Your LS-DYNA® Simulations

  Gaëtan Van den Bergh, Yves Lemmens - LMS International

  Automotive companies have become increasingly educated in safety related performance, setting the bar higher for automotive crashworthiness. Process Automation and Design Optimization (PIDO) tools help LS-DYNA users to reach these safer designs in a shorter period. In this paper, various application cases are used to demonstrate how PIDO tools can leverage your existing simulation codes. In the first application case, a multi-disciplinary crash optimization case, executed at an automotive company, is discussed in detail. How can you optimize systems while taking into account multiple different government safety regulations? How can you reduce the throughput time of your CPU intensive LS-DYNA simulations? How can you manage and visualize the obtained data? During the second application case, an industrial example of an A-pillar trim design optimization for occupant head safety is presented. During the optimization the variability present in actual testing conditions is also taken into account. The analysis aims mainly at minimizing head injury by using a Reliability-based approach that takes into account a probabilistic constraint formulation

• Multi-disciplinary Optimization using LS-DYNA®

  Mr. Azhar rehmani A. Saiyed, MS, B.Eng., Wayne State University;, Dr. Bijan Khatib Shahidi, PhD, MBA, US Army, TARDEC;, Mr. Madan Vunnam, MS, PMP®, US Army, TARDEC

  Crashworthiness, NVH (Noise Vibration & Harshness) are two distinct as well as very inter-connected attributes/disciplines of vehicle development process. As objectives of both are very differing, it is a challenge to design a vehicle equally performing in both with the global objectives of mass reduction and comfort. LS-OPT® is the tool, which can perform a multi-disciplinary optimization. Here we will perform a frontal crash of the vehicle (/frame) and Optimize as per the FMVSS 208. On the other side, Vibration Analysis and optimization of BIW for the same vehicle will be conducted. Then, we will perform an overarching Multi-Disciplinary Optimization and compare it with the individual optimization. Lastly, we will run a LS-DYNA model with optimized parameters for the validation of the model.

• Multi-Disciplinary Optimization of a Sedan Using Size and Shape Parameterization

  Nitin Sharma, Suthan, Jim Colins, Basant Sharma - Detroit Engineered Products Inc., Troy, MI

  In vehicle development activity there are different disciplines with their own set of requirements that need to satisfied in order to get a successful product. Traditionally, the simulations were performed for different disciplines but at the time of optimization, Single Discipline Optimization (SDO) was usually performed and later confirmatory runs were done for the other disciplines. This process resulted in a time consuming loop of running several iterations with different disciplines and engaged people from these disciplines to make the optimized design meet the performance targets. Quite often these approaches led to tradeoffs made for design requirements or significant deviations from the optimized design obtained by running SDO. Multidisciplinary Optimization (MDO) addresses this shortcoming and takes into account different disciplines for optimization, thus reducing the need to iteratively evolve the design for different disciplines. Though this process has its benefits but those benefits are overridden with the setup time required for MDO. The major proportion of the setup time is consumed in defining shape variables on full vehicle FE model that has all types of connections as the process needs to be repeated for different disciplines. As a result an alternate methodology is sometimes pursued to create concept models from the full vehicle FE models thereby reducing the complexities of a full vehicle FE model. This approach not introduces approximation in the entire process by idealizing the detailed FE model but also requires this definition of shape variables separately for each discipline. In this paper, the MDO was performed on a full vehicle by considering Crash and NVH load cases. These two disciplines were considered to provide a process and to demonstrate its benefits. LS-DYNA® was used for crash simulations and Nastran was the solver used for NVH load cases. This process of MDO has been successfully applied to different vehicle programs including disciplines like durability, vehicle dynamics, occupant simulations, CFD etc. Due to IPR restrictions, the program specific work is not shared in this paper. The present process demonstrated on a sedan with different types of design variables defined for Crash and NVH load cases. The MDO is performed with the objective to reduce mass of the vehicle without any significant performance degradation. The approach presented here uses advance features of DEP’s Meshworks and provides the processes through which MDO could be carried out without sacrificing the complexity of the full vehicle FE model. It expedites the entire process by offering faster turnaround time.

• Multi-disciplinary Topology Optimization for Vehicle Bonnet Design

  David Salway (GRM Consulting Ltd), Tayeb Zeguer (Jaguar Land Rover Ltd)

  Bonnet Pedestrian Head lmpact and Structural Stiffness and Strength targets have conflicting design requirements which currently result in design compromises, and the current CAE methods use different models and solvers. This paper highlights a new CAE capability to provide Multi-Disciplinary Optimization of bonnet geomety to achieve the conflicting Pedestrian Head Impact and structural stiffness/strength targets at lowest weight and cost. The aim has been to combine all bonnet load cases using one code "LS-DYNA" and cary out trade-oft and optimize weight using LS-OPT. A new developed topology process employing VR&D Genesis for HIC optimisation is presented and compared mih LS-TASC tools for a generic bonnet design.

• Multi-Layer Aluminum Formability Assessment Using Composite Shells in LS-DYNA® with the Linear Fracture Line Approach

  Dr. Richard Burrows, Novelis Global RD&T Center, Kennesaw GA, USA

  Multi-layer aluminum sheet offers exciting design possibilities for automotive applications due to the outer layer having a ductility that suppresses fracture in drawing processes involving a high degree of bending. Formability assessment of multi-layer aluminum products such as AF200 thus offer a challenge to traditional techniques used in the industry such as Forming Limit Diagrams, owing to this large resistance to bending dominated fracture. A modelling technique using standard LS-DYNA release features is set forth and discussed.

• Multi-Material Topology Optimization in LS-TaSC™ Using Ordered SIMP Interpolation

  Satchit Ramnath (The Ohio State University), Mariusz Bujny, Stefan Menzel (Honda Research Institute Europe GmbH), Nathan Zurbrugg, Duane Detwiler (Honda Research & Development Americas)

  Topology optimization allows for the design of structures with an optimum distribution of material for a given set of load cases that may have conflicting requirements. Though the methods used in topology optimization help to generate better and novel designs, they are generally limited to a single material only. In contrast, modern vehicle structures are composed of parts made of multiple materials, exhibiting usually superior performance compared to single-material designs. In order to support the design process of such structures, this problem requires the ability to use multi-material optimization methods within commercially available software like LS-TaSC, to optimally distribute multiple materials within a single design domain. In this paper, a method for integration of the ordered SIMP in LS-TaSC to realize multi-material TO is proposed and evaluated using a solid beam that is subject to static and crash load cases. The optimization uses the updated material distribution, based on ordered SIMP, to assign material/density values to elements in the design domain. To demonstrate the potential of the multi-material TO and validate the results, the obtained topologies are compared to single material designs as well as to the structures optimized using the state-of-the-art gradient-based approach based on ordered SIMP. The results show that LS-TaSC can be successfully used for deriving multi-material structures superior to the single-material designs. Finally, due to the low computational costs, the method seems to be suitable for the optimization of large-scale industrial models.

• Multi-phase welding simulation, experimental validation and exploratory bending simulation of structural steel weldments

  Tobias Girresser, Tobias Loose

  To predict the load-bearing capacity of a welded joint, it is necessary to know the structure that will be formed. In recent decades, welding simulation has evolved and now offers the possibility to determine the required material properties after welding [1]. Computational welding mechanics (CWM) is a calculation method that can be used to calculate distortions, mechanical stresses, and strains as well as microstructure states and microstructure transformations in thermally joined components [2, 3].

• Multi-physics applications for ground vehicle aerodynamics: structural thermal radiation coupled to CFD for a more accurate temperature prediction

  Facundo Del Pin, Art Shapiro, Iñaki Caldichoury, Rodrigo R. Paz, Julie Anton (LSTC)

  Thermal radiation is an important heat transfer mechanism which may greatly influence the mechanical behavior of structural parts of a vehicle when they are exposed to aerodynamic loads. This effect is even more evident in high performance vehicles where the engines are running at ever higher temperatures and the structure is built using lighter parts with less conventional materials. The radiated heat from the engine or exhaust system will increase the temperature in parts of the vehicle that are not directly in contact or even physically close. The increased temperature will soften the materials making it more prone to deformation in the presence of the fluid loads. The problem then requires the coupling of the radiation solver with a fluid mechanical solver to accurately predict the temperature of the mechanical part interacting with the air temperature and the deformation of that part when interacting with the air pressure. In the current work the first case will be studied. The conjugate heat transfer solver will be applied to the problem of predicting the temperature in parts of a vehicle when it is heated by radiation from the engine taking into account the cooling effect of the air.

• Multi-scale Approach for CFRP Composite Simulation by JSTAMP/NV and DIGIMAT

  Noriyo Ichinose - JSOL Corporation

• Multi-scale Material Modeling Applied from Specimen to Full Car Level using LS-DYNA®

  Sylvain Calmels, e-Xstream Engineering

  Tomorrow’s vehicles architectures will involve an increasing number of materials. Within this worldwide shared status, fiber reinforced materials are finding their way into not only aesthetic components but also semi-structural and structural components. Today, the question of how to accurately model such parts is not a topic of discussion anymore. All solutions dedicated to these materials proposed on the CAE market are based on multi-scale material modeling techniques. However, even if the modeling strategy has now been adopted, its integration into the whole vehicle design process from the lowest level up to the most complex one on full car is still a challenging task.

• Multi-Scale Material Parameter Identi­fication using LS-DYNA and LS-OPT

  N. Stander, A. Basudhar, U. Basu, I. Gandikota (LSTC), V. Savic (General Motors Company), X. Sun, K. Sil Choi, X. Hu (Pacific Northwest National Labora­tory), Prof. F. Pourboghrat, T. Park, A. Mapar (Michigan State University), S. Kumar, H. Ghassemi-Armaki (Brown University), F. Abu-Farha (Clemson University)

  Ever-tightening regulations on fuel economy and carbon emissions demand continual innovation in finding ways for reducing vehicle mass. Classical methods for computational mass reduction include sizing, shape and topology optimization. One of the few remaining options for weight reduction can be found in materials engineering and material design optimization. Apart from considering different types of materials by adding material diversity, an appealing option in automotive design is to engineer steel alloys for the purpose of reducing thickness while retaining sufficient strength and ductility required for durability and safety.

• Multi-Scale Modeling of Crash & Failure of Reinforced Plastics Parts with DIGIMAT to LS-DYNA interface

  L. Adam, A. Depouhon, R. Assaker - e-Xstream engineering

  This paper deals with the prediction of the overall behavior of polymer matrix composites and structures, based on mean-field homogenization. We present the basis of the mean-field homogenization incremental formulation and illustrate the method through the analysis of the impact properties of fiber reinforced structures. The present formulation is part of the DIGIMAT [1] software, and its interface to LS-DYNA, enabling multi-scale FE analysis of theses composite structures. Impact tests on glass fiber reinforced plastic structures using DIGIMAT coupled to LS-DYNA allow to analyze the sensitivity of the impact properties to the polymer properties, fibers’ concentration, orientation, length ... For such impact applications the material models used for the polymer matrix are usually based on nonlinear elasto-viscoplastic laws. Failure criterion can also be defined in DIGIMAT at macroscopic and/or microscopic levels and can be used to predict the stiffness reduction prior to failure (i.e. by using the First Pseudo Grain Failure model). Theses failure criterion can be expressed in terms of stresses or strains and use strain rate dependent strengths. Finally, the interface to LS-DYNA, available for the MPP version, will be used to run such multi-scale FE simulations on Linux DMP clusters. The application will thus involve: LS-DYNA MPP to solve the structural problem. DIGIMAT-MF as the material modeler. DIGIMAT to LS-DYNA MPP strongly coupled interface to perform nonlinear multi-scale FEA DIGIMAT-MF composite material models based on : - An elasto-viscoplastic material model for the matrix, - An elastic material model for the fibers as well as the fiber volume content, fiber length and fiber orientation coming from an injection code, - Failure indicators computed at the microscopic level.

• Multi-Scale Modeling of Crash & Failure of Reinforced Plastics Parts with DIGIMAT to LS-DYNA interface

  L. Adam, A. Depouhon, R. Assaker - e-Xstream engineering

  This paper deals with the prediction of the overall behavior of polymer matrix composites and structures, based on mean-field homogenization. We present the basis of the mean-field homogenization incremental formulation and illustrate the method through the analysis of the impact properties of fiber reinforced structures. The present formulation is part of the DIGIMAT [1] software, and its interface to LS-DYNA, enabling multi-scale FE analysis of theses composite structures. Impact tests on glass fiber reinforced plastic structures using DIGIMAT coupled to LS-DYNA allow to analyze the sensitivity of the impact properties to the polymer properties, fibers’ concentration, orientation, length ... For such impact applications the material models used for the polymer matrix are usually based on nonlinear elasto-viscoplastic laws. Failure criterion can also be defined in DIGIMAT at macroscopic and/or microscopic levels and can be used to predict the stiffness reduction prior to failure (i.e. by using the First Pseudo Grain Failure model). Theses failure criterion can be expressed in terms of stresses or strains and use strain rate dependent strengths. Finally, the interface to LS-DYNA, available for the MPP version, will be used to run such multi-scale FE simulations on Linux DMP clusters. The application will thus involve: LS-DYNA MPP to solve the structural problem. DIGIMAT-MF as the material modeler. DIGIMAT to LS-DYNA MPP strongly coupled interface to perform nonlinear multi-scale FEA DIGIMAT-MF composite material models based on : - An elasto-viscoplastic material model for the matrix, - An elastic material model for the fibers as well as the fiber volume content, fiber length and fiber orientation coming from an injection code, - Failure indicators computed at the microscopic level.

• Multi-Scale Modeling of the Impact and Failure of Fiber Reinforced Polymer Structures using DIGIMAT to LS-DYNA Interface

  L. Adam, R. Assaker and R. Ramaya - e-Xstream engineering S.A.

  This paper deals with the prediction of the overall behavior of polymer matrix composites and structures, based on mean-field homogenization. We present the basis of the mean-field homogenization incremental formulation and illustrate the method through the analysis of the impact properties of fiber reinforced structures. The present formulation is part of the DIGIMAT [1] software developed by e-Xstream engineering. An interface between LS-DYNA and DIGIMAT was developed in order to perform multi-scale FE analysis of these composite structures taking into account the local, anisotropic, nonlinear and strain-rate dependent behavior of the material. Impact simulations are performed on glass fiber reinforced polymer structures using DIGIMAT interface to LS-DYNA. These analyses enable to highlight the sensitivity of the impact properties to the fibers’ concentration, orientation and length.

• Multi-Scale Modelling of Textile Structures in Terminal Ballistics

  Rimantas Barauskas - Kaunas university of technology, Lithuania

  An efficient finite element model of the ballistic impact and perforation of the woven fabrics structures has been developed in LS-DYNA. The bullet has been considered as a deformable body in contact with the fabric package presented by interwoven yarn structure. The model of the weave has been created by presenting the multifilament yarns by thin shell elements the thickness of which represents the real thickness of yarns. The total model of the fabric has been developed by employing the multi-scale approach. The “woven” zone in the vicinity of the bullet impact has been joined with the uniform surrounding areas of textile presented by membrane elements. The junction between the two types of zones of the fabric has been performed by means of the tie constraint and by proper adjustment of material parameters ensuring the minimum cumulative wave propagation speed error along selected directions. The model has been verified by comparing the response of the structure with the reference solution obtained by solving the full woven structure model. Physical and numerical experiments have been performed in order to identify the material model parameters.

• Multi-scale Validation of a Butyl Rubber Neck Model for an Anthropomorphic Testing Device Designed for Underbody Blast

  Alexander M Baker, Jeremy M Schap, F. Scott Gayzik, Wake Forest School of Medicine, Dept of Biomedical Engineering, Center for Injury Biomechanics;, Nicholas A Vavalle, Robert S Arminger2, Mark M Angelos, Johns Hopkins Applied Physics Laboratory;, Randolph S Coates, WIAMan Engineering Office, U.S. Army Research Lab

  Underbody blast is a significant injury risk for the modern warfighter, and a well-validated human surrogate for underbody loading environments can assist in preventing or mitigating injury. We present a selection methodology and hierarchical validation of the neck material model for the Warrior Injury Assessment Manikin (WIAMan) LS-DYNA® model focusing on accuracy, consistency, and robustness. All simulations were run with LS-DYNA R 8.0.0

• Multi-stage Analysis Approach to Low Speed Vehicle Impacts using the *SENSOR Keywords

  Hari Patel, Ben Crone

  The low speed impact tests outlined in ECE R42 and FMVSS 581 consist of multiple consecutive impacts on a vehicle bumper to assess vulnerability to damage and repairability. Typical CAE approaches to assessing multi-stage analyses involve running each stage of the analysis individually, inputting deformations, stresses, and strains from the end of the previous analysis. This approach typically requires manual model editing before each analysis, which is time consuming and increases the risk of human error.

• Multiaxial Fatigue Analysis with LS-DYNA®

  Yun Huang (Livermore Software Technology, an ANSYS company), Anders Jonsson, Marcus Lilja (DYNAmore Nordic AB)

  Fatigue life is an important dimensioning criterion within product development. Several tools and software are today available and are widely used for fatigue assessment within the CAE process. To further improve the capabilities for integrated fatigue analysis in LS-DYNA, a time domain fatigue solver has been developed and implemented by LST (an ANSYS company), as a compliment to the already existing frequency domain fatigue solvers. As of coming releases of LS-DYNA, different options for fatigue analyses will be available, based on the results from general load cases and structures including e.g. non-linearities, non-proportional and multiaxial loading conditions. The time domain fatigue analysis can be based on stress or strain results from all time domain solvers (implicit, explicit, thermal, FSI, etc.) in LS-DYNA. The stress or strain state of the elements is usually three dimensional, especially for the parts under multiaxial loading cases like bending or twisting. However, the standard procedure to obtain the SN curve or EN curve is based on nominal stress or strain of the specimen, which is a scalar not a tensor. Several options to deal with the multiaxial stress state for fatigue analysis have been implemented in LS-DYNA (keyword *FATIGUE_MULTIAXIAL). They include 1. Running fatigue analysis based on an equivalent stress index (e.g. von Mises stress); 2. Running fatigue analysis on multiple planes and picking the highest damage ratio across the planes as the fatigue damage ratio of the element; 3. Locating a critical plane first and projecting the whole stress history to the critical plane and then running fatigue analysis on the critical plane. Several examples are given in this paper, to discuss the different options for multiaxial fatigue analysis, including a crankshaft model and a cylinder bar model with a groove. Validation has been performed by comparing the simulation results from simple test cases to analytical results from the same load cases. Also, a comparison of the fatigue analysis results from LS-DYNA to the results from the fatigue postprocessing module mFAT (a plug-in to the post-processor META) is presented in this paper.

• MULTIDISCIPLINARY DESIGN OPTIMIZATION OF AUTOMOTIVE CRASHWORTHINESS AND NVH USING LS-OPT

  K.J. Craig - University of Pretoria, Nielen Stander - Livermore Software Technology Corporation, D.A. Dooge - DaimlerChrysler Corporation, S. Varadappa - Quantum Consultants, Inc.

  This paper describes the multidisciplinary design optimization of a full vehicle to minimize mass while complying with crashworthiness and Noise, Vibration and Harshness (NVH) constraints. A full frontal impact is used for the crashworthiness simulation in the nonlinear dynamics code, LS-DYNA. The NVH constraints are evaluated from an implicit modal analysis of a body-in- white vehicle model using LS-DYNA. Seven design variables describe the structural components of which the thickness can be varied. The crashworthiness constraints relate to crush energy and displacement, while the torsional frequency characteristics are obtained from the modal analysis. The Multidisciplinary Feasible (Fully Integrated) formulation, in which full sharing of the variable sets is employed, is used as the reference case. In an attempt to investigate global optimality, three starting designs are used. Based on a Design of Experiments analysis of variance of the fully-shared variable results for each starting design, discipline-specific variables are selected from the full set using the sensitivity of the disciplinary responses. The optimizer used in all cases is the Successive Response Surface Method as implemented in LS-OPT. It is shown that partial sharing of the variables not only reduces the computational cost in finding an optimum due to fewer, more sensitive variables, but also leads to a better result. The mass of the vehicle is reduced by 4.7% when starting from an existing baseline design, and by 2.5% and 1.1% when starting from a lightest and heaviest starting design respectively.

• Multidisciplinary Design Optimisation Strategies for Lightweight Vehicle Structures

  A. Prem, C. Bastien, M. Dickison (Coventry University)

  The future of automobiles will be driven by lightweight structures and highly efficient powertrains. The TARF-LCV EPSRC funded project (Towards Affordable, Closed-Loop Recyclable Future-Low Carbon Vehicle Structures) aims to provide a strong scientific and technological underpinning to future LCV development in areas of advanced materials, low carbon manufacturing technologies, holistic mass-optimised vehicle structure design and closed-loop recycling of End of life vehicles.

• Multidisciplinary Optimisation and the Design for 6 Sigma

  Dr. Tayeb Zeguer - Jaguar Cars Ltd

• Multiphase Flow CESE Solver in LS-DYNA®

  Zeng-chan Zhang, Grant Cook, Jr., Kyoung-su Im (Livermore Software Technology, an ANSYS Company)

  In this paper, we will introduce a new capability of multiphase flow simulations in the LS-DYNA CESE compressible solvers. It is a hybrid multiphase flow model proposed by L. Michael [1]. This model is targeted for high-speed explosions, especially shock-to-detonation transition in liquid nitromethane. While the space-time conservation element and solution element (CESE) method, originally proposed by Chang [2], is designed for solving compressible flows, it is especially good for high-speed flows with complicated flow patterns. So we will use the CESE method to solve this hybrid multiphase flow model, and this approach will avoid a lot of complicated and time consuming treatments such as Riemann solvers and the Strang-splitting that are used in Ref.[1]. Our numerical examples show that we can get similar results using the CESE method. In the next sections, we will first give a brief introduction to the hybrid multiphase model, then the CESE method. Finally, we will give some numerical examples.

• Multiphysics Analysis of Automotive Components for Product Portfolio Optimization

  Santiago José Javier Torres García, Eduardo David Berdeal Zertuche, Ramiro Elizondo Villarreal

  In this study, the pillars A, B and C from the Body-in-White (BIW) of a pickup passenger vehicle were considered, and the steels used for these components were identified based on the A2MAC1 platform, the SAEJ2947 standard, and state-of-the-art literature. Subsequently, these steels were compared with the client's product portfolio to propose a steel that meets the characteristics demanded by the automotive market for each of the components considered in the BIW. Next, the performance of each of the three pillars with these steels was validated and compared through crashworthiness simulations using Finite Element Analysis (FEA) with ANSYS LS-DYNA software. These simulations modeled the behavior of the pillars on side impact tests, with meshed parts based on the 2014 Chevrolet Silverado 1500 FEA model from the CCSA of the George Mason University. The impact speed was based on the Oblique pole side impact testing protocol from Euro NCAP; the time simulation was based on the Side impact Crashworthiness Evaluation 2.0 Rating Guidelines from the IIHS. To compare materials’ behavior, different curves were defined for each case. The tested materials were evaluated by comparing internal energy and displacement on each of the three pillars. Finally, results regarding the behavior of the different materials were discussed.

• Multiphysics SPH simulation of flow drilling process

  A. Journaux, T. Legaud, V. Lapoujade (DynaS+)

  Flow drilling is an alternative drilling solution for metal plates up to several centimeters. Using a conical tool, the process combines high rotation speed and high pressure to initiate friction and heat up the plate material locally in contact with the tool. As a consequence, the heated material has its mechanical characteristics reduced and is subjected to a very large plastic deformation. The surplus of matter is not wasted but is shaped into a collar above the metal plate and a socket below. These bulges induce a local additional thickness enabling a direct threading without added parts (bolt...).

• Multiscale Model Analysis of the Effects of Martensite Morphology and Martensite Volume Fraction on the Mechanical Property of Dual-Phase (DP) Steels: Parametric Study

  Tarek Belgasam, PhD, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99163 (USA) Mechanical Engineering Department, Faculty of Engineering, University of Benghazi, Benghazi, Libya

  Multiscale material modeling is important for directing the material design of heterogeneous materials with concurrent improvements in mechanical properties. In this study, the plastic deformation of DP steels with different microstructures features namely martensite aspect ratio, and martensite volume fraction was investigated. A new methodology that studies the effects and interactions of martensite aspect ratio (equiaxed versus elongated) and martensite volume fraction on the mechanical behavior of DP steels was developed. A multiscale material and structure model using a dislocation density based nonlinear elastic-viscoplastic model was used to predict the mechanical behavior of DP steels under quasi-static loading condition.

• Multiscale Simulation of Short-Fiber-Reinforced Composites: From Computational Homogenization to Mechanistic Machine Learning in LS-DYNA

  H. Wei,C. T. Wu, D. Lyu, W. Hu, F. Rouet, K. Zhang, P. Ho (Ansys/LST), H. Oura, M. Nishi (JSOL), T. Naito (Honda), L. Shen (CoreTech System)

  Injection-molded short-fiber-reinforced composites (SFRC) have been widely used for structural applications in automotive and electronics industries. Due to the heterogeneous microstructures across different length scales, the nonlinear anisotropic behaviors of SFRC are very challenging to model. Therefore, an effective multiscale approach that links the local microscopic properties (e.g., fiber orientation, fiber volume fraction) to the global behaviors is required. To this end, multiscale analysis functions are recently developed in the engineering simulation software LS-DYNA to enable high-fidelity micromechanical finite element analysis, mechanistic machine learning-based reduced-order modeling, and accelerated concurrent multiscale simulation of SFRC composite structures.

• Multiscale Simulations of Material with Heterogeneous Structures Based on Representative Volume Element Techniques

  Zeliang Liu1, C. T Wu1, Bo Ren1, Roger Grimes, Livermore Software Technology Corporation, Livermore, CA 94551, Wing Kam Liu, Northwestern University, Evanston, IL 60208

  This paper presents a concurrent multiscale simulation framework for materials with heterogeneous structures (e.g. composite). This avoids the burdens of finding the macroscale phenomenological models and tedious calibration processes by directly establishing the connection between the microstructure and macro-response through computational homogenization. In the homogenization process, the model links every macroscopic integration point to a Representative Volume Element (RVE) of the microstructure, and macroscopic response is obtained by solving the RVE boundary value problem. Direct numerical simulation (DNS) techniques (e.g. FEM) for RVE analysis are capable of providing accurate high-fidelity material response data for complex phase morphology and behavior. Meanwhile, it is necessary to accelerate the RVE analysis using advanced model reduction techniques to enable efficient concurrent simulations.

• Necking and Failure Simulation of Lead Material Using ALE and Mesh Free Methods in LS-DYNA ®

  Sunao Tokura (Tokura Simulation Research)

  After the Fukushima Daiichi nuclear disaster in 2011, the need of experiment to predict failure of the structures including pipes and vessels in nuclear power plant in case of large earthquake or tsunami has been increasing. However it is dangerous and expensive to perform such experiments using real structural material, e.g., 304 stainless steel as very large test facility is needed to cause realistic failure. Alternatively, the idea to use pure lead (100 % Pb) and lead alloy in the experiments has been proposed as alternatives of real materials used in nuclear power plant. Lead is ductile material and lead alloy involving antimony (Sb) is brittle material. So both ductile and brittle failure modes can be reproduced easily in laboratory tests using these materials. For the simulation of failure of the structures, ductility of lead should be modeled accurately. High ductility and large necking are observed in the tensile test of pure lead rod. In this paper, simulation of necking and failure of the lead rod tensile test is tried using ALE and mesh free techniques, i.e., EFG, SPH and SPG implemented in LS-DYNA in addition to the conventional Lagrangian FEM approach, and the results of the simulation are compared and discussed with the experimental result.

• Neural network representation of mechanical fasteners in large-scale analyses

  V. André, D. Morin, M. Costas, M. Langseth (NTNU)

  This paper presents an artificial neural network (NN) modeling approach for representing mechanical fasteners in large-scale finite element crash simulations for explicit analysis using LS-DYNA version R9.3.1. The NN-model is established to describe the local force-deformation response of point-connectors in automotive applications like self-piercing-rivets and flow-drill-screws. The behaviour from initial loading until failure or unloading is covered. Various architectures and complexities of feedforward NNs were evaluated and trained based on synthetic experiments generated from the constraint model proposed by Hanssen et al. [1]. The constraint model is available as *CONSTRAINED_SPR2 but was used in form of a cohesive element (8-noded, 4-point cohesive element with offsets for use with shells).

• New Conjugate-Heat Transfer Solvers in the Compressible CESE Solver in LS-DYNA ®

  Grant O. Cook, Jr. and Zeng-Chan Zhang (Livermore Software Technology Corp.)

  Standard coupling methods for performing conjugate-heat transfer between a compressible flow and a structural thermal solver have been previously implemented in the LS-DYNA Conservation Element/ Solution Element (CESE) compressible flow solvers. Unfortunately, they do not conserve energy. One consequence of this in conjugate- heat transfer calculations is that the CESE solver’s conservation properties are compromised by the errors in the energy transferred at the interface between the structure and the fluid. And this error subsequently propagates to the interior of the fluid domain. In cases where a steady-state solution is sought, another consequence is that these energy errors may grow in time to the point that an incorrect steady state solution is computed. While one of the goals of these solvers is avoid non-physical and other erroneous solutions, it needs to be pointed out that the accuracy achieved is still a function of the fidelity of the computational mesh required to resolve the real solution. This is of particular concern in conjugate-heat transfer problems where the fluid boundary layer can be very thin, and large changes in the fluid variables in this fluid boundary layer are typical. Recently, we have implemented new energy-conservative methods for conjugate heat transfer involving compressible gases in the CESE conjugate-heat transfer solvers. These new solvers have been validated using an analytic test that has an initial singularity, and is thus quite challenging. The new method will be described, and discussed in the context of three types of solvers: 1) a fixed mesh Eulerian CESE solver coupled to a rigid structure, 2) moving mesh CESE FSI solvers, and 3) immersed-boundary method (IBM) CESE FSI solvers [1].

• New Design Considerations for the Calibration of Rubber-Like Materials

  Y. Lev, K.Y. Volokh (Technion Institute of Technology), A. Faye (Indian Institute of Technology)

  Rubber-like materials have unique characteristics that make them industrially very attractive. These materials can reach up to stretches of about 6-7 while staying hyper-elastic. Only a few studies that deal with these high level up to failure stretches are available. In addition, information regarding the temperature effect on fracture is absent in the literature. This work summarizes some recent aspects regarding the calibration of rubber-like materials reaching ultimate deformation (strength) under high operating temperatures. Our approach to modelling rubber fracture is based on the elasticity with energy limiters theory. Constitutive relations have been developed to generalize this description in order to include the thermo-elastic behavior. A relation for the temperature dependent energy limiters, and a new form for the thermal energy contribution are offered. The presented theory is used for calibration of rubber-like materials using LS-DYNA®. Our work also includes the design and set-up of a homemade test chamber for the uniaxial and bulge test (inflation of balloon test) cases. These tests are subjected to temperatures in the range of 25℃ to 90℃. The equi-biaxial conditions are extracted indirectly from the bulge test data by performing iterative finite element simulations that are done up to a sufficient fit to the bulge experiment results. The importance of a simultaneous calibration using both uniaxial and biaxial load cases together is highlighted. Material parameters found are significantly better than the parameters extracted by rubber manufacturers and labs that usually use uniaxial tests in room temperature only. The methodology used allows the correct modeling of ultimate properties as a function of high common operating temperatures for rubber-like materials. The findings can serve as new design considerations for engineers using these materials.

• New Design of Roadside Pole Structure: Crash Analysis of Different Longitudinal Tubes using LS-DYNA

  Dr. Ahmed Elmarakbi, Mr. Niki Fielding - University of Sunderland, United Kingdom

  This paper is an investigation into the design of an energy absorbing street pole, concerning the frontal impact of a vehicle. With design engineers now are looking at other ways to improve vehicle occupant safety by focusing on the advantages that can be achieved by improving the crashworthiness of street furniture. The study of axial crush behaviour of metal materials are investigated along with a number of variables such as cross-sectional shape, shell thickness, materials, as well as the velocity affects on tubes. Different simulations are carried out on the effects of bedded crumple initiators placed a various heights from the top of the tube, in determining the desired value of peak load reduction, along with the effect in energy absorption of the tube. With the conclusion of the desired variables for the design of an energy absorbing tube, the tubes are placed 90 degrees to that of the base of the model street pole to modify the pole design . Simulation of frontal impact of a vehicle and street pole are analysed and compared to that of the energy absorbing street pole concept. Studies are carried out by numerical simulation via the explicit finite element code LS- DYAN. Results compare the absorbed energy and the deflection of each variable, and recommend optimum design for the pole structure which improved vehicle crashworthiness.

• New Design of Roadside Pole Structure: Crash Analysis of Different Longitudinal Tubes using LS-DYNA

  Dr. Ahmed Elmarakbi, Mr. Niki Fielding - University of Sunderland, United Kingdom

  This paper is an investigation into the design of an energy absorbing street pole, concerning the frontal impact of a vehicle. With design engineers now are looking at other ways to improve vehicle occupant safety by focusing on the advantages that can be achieved by improving the crashworthiness of street furniture. The study of axial crush behaviour of metal materials are investigated along with a number of variables such as cross-sectional shape, shell thickness, materials, as well as the velocity affects on tubes. Different simulations are carried out on the effects of bedded crumple initiators placed a various heights from the top of the tube, in determining the desired value of peak load reduction, along with the effect in energy absorption of the tube. With the conclusion of the desired variables for the design of an energy absorbing tube, the tubes are placed 90 degrees to that of the base of the model street pole to modify the pole design . Simulation of frontal impact of a vehicle and street pole are analysed and compared to that of the energy absorbing street pole concept. Studies are carried out by numerical simulation via the explicit finite element code LS- DYAN. Results compare the absorbed energy and the deflection of each variable, and recommend optimum design for the pole structure which improved vehicle crashworthiness.

• New Development of the Gap Closure Feature in LS-DYNA ICFD

  P. Huang, F. Del Pin, I. Çaldichoury, R. R. Paz (Ansys/LST)

  There is a great interest in the fluid-structure interactions (FSI) of flow mechanics around valves in the heart or in mechanical parts. The capability to allow flow blockage due to the valve closure is very important.

• New developments and future road map for the ICFD solver in LS-DYNA

  F. Del Pin, R. R. Paz, P. Huang, I. Çaldichoury (Ansys/LST)

  This paper will discuss some of the new additions that will be part in the R13.0 release for the Incompressible CFD (ICFD) solver in LS-DYNA. The paper will also cover some of the highlights of R12. In the past year there has been an increased interest in the model of problems that involve the simulation of free surfaces, Fluid Structure Interaction (FSI) and porous media flow. These topics will be discussed, and the new features/improvements will be presented. The road map is a collection of feature requests from LS-DYNA distributors, Ansys ACE organization, academic collaborators and customers. Based on this a brief discussion the top topics will be presented including immersed interface techniques, gap closure models, multi-species transport and tighter integration with Ansys tools.

• New Developments in LoCo – the Innovative SDM System

  M. Thiele (SCALE)

  DYNAmore GmbH has founded a new wholly-owned subsidiary known as SCALE GmbH. The aim behind this move is to offer software solutions and IT services for process and data management and for FE methods development in the automotive industry. In the past years, DYNAmore has created a variety of different software products under contract of AUDI. The reason for establishing SCALE GmbH is to further develop and market LoCo and other software products both within the Volkswagen group and beyond it as well.

• New developments in LS-OPT Version 3.2

  Nielen Stander, Willem Roux - Livermore Software Technology Corporation

  An overview of LS-OPT features is given with special emphasis on the major new optimization features available in LS-OPT Version 3.2. These include GUI support for parameter identification, confidence intervals for individual optimal parameters, point plotting as an enhancement to 3-D metamodel plotting, matrix expressions, coordinatebased result extraction and retry features for job distribution

• New developments in material testing at very high strain rates

  R. Grams (University of Siegen)

  The determination of material properties under high-speed loading has been a challenge for many years. Structural vibrations, also called system ringing, in conventional testing machines deteriorate the quality of force measurement, which makes a precise determination of stress-strain curves and corresponding mechanical properties impossible. In this work, a new specimen geometry with its basic mechanical principle and the corresponding measurement technique are presented and discussed. The new method allows the determination of true stress-strain curves at high strain rates free from oscillation. Due to the additionally minor plastic deformation area in the new Generation III specimen, a quasi-movable bearing condition for the specimen fixation was created. Forces, based on the natural frequency of the specimen, deform the cross-section and create a displacement, which keeps the kinetic energy of the measurement area high. In this way, the elastic ringing effect has been reduced significantly. Any kind of filtering, smoothing or similar manipulations of the result are no longer needed. This new method has been validated on three steels types and one type of aluminium alloy with different strain hardening behavior through measurements and numerical analysis. The Generation III specimen can also be used for the quasi-static test and cover the strain rate range from 4.4·10-4 - 103 /s accordingly.

• New Developments in the Compression of LS-DYNA Simulation Results using FEMZIP

  Rodrigo Iza Teran, Clemens-August Thole, Rudolph Lorentz - Fraunhofer Institute for Algorithms and Scientific Computing SCAI

  The standard usage of simulation as part of the automotive design process and increased computer power has increased the demand on archiving resources. This data may be reused several times during the development process and reused later for new models. Compression of the simulation results reduces both the archive size and the access times. This is why FEMZIP was developed several years ago. FEMZIP was specially designed for the compression of crash simulation results. We report on the improvements of FEMZIP both in regard to speed and to compression factors. FEMZIP is now also available built into several postprocessors. This means that these postprocessors can read and process compressed files directly. As a consequence of the improvements in FEMZIP, the postprocessors can display the compressed files faster than uncompressed files.

• New Developments of Frequency Domain Acoustic Methods in LS-DYNA

  Yun Huang - Livermore Software Technology Corporation, Mhamed Souli - University of Lille, Rongfeng Liu - JSOL Corporation

  This paper presents the new developments of finite element methods and boundary element methods for solving vibro-acoustic problems in LS-DYNA. The formulation for a frequency domain finite element method based on Helmholtz equation is described and the solution for an example of a simplified compartment model is presented. For boundary element method, the theory basis is reviewed. A benchmark example of a plate is solved by boundary element method, Kirchhoff method and Rayleigh method and the results are compared. A dual boundary element method based on Burton-Miller formulation is developed for solving exterior acoustic problems which were bothered by the irregular frequency difficulty. Application of the boundary element method for performing panel contribution analysis is discussed. These acoustic finite element and boundary element methods have important application in automotive, naval and civil industries, and many other industries where noise control is a concern.

• New Eigen Solver Technology in LS-DYNA

  Roger G. Grimes, François-Henry Rouet

  The Linear Algebra Team of Ansys LST has added two new eigen solver technologies for the standard vibration analysis problem of structural mechanics. The first, LOBPCG, is based on iterative solution technology to reduce the cost of the direct solution used by the default eigen solver Lanczos. The second, Fast Lanczos, is a new innovative implementation of the Block Shift and Invert Lanczos algorithm targeting the computation of thousands of eigenmodes with less accuracy for the Noise-Vibration-Harshness (NVH) application.

• New Electrode Design for GEPI Shot to Test Curved Sample

  G. Le Blanc, P. L'Eplattenier, I. Caldichoury (LSTC)

  This study is relative to material behaviour characterization using the GEPI pulsed power device. First, the GEPI device will be briefly described. At the moment, only planar samples can be tested on GEPI. However, it is very attractive to test curved samples to comply with operational requirements. The adaptation of GEPI to curved sample would allow the characterization of material samples directly extracted from operational cylindrical structures. The GEPI performance is mostly based on high-precision electrode manufacturing. The feasibility study is conducted with the help of LS-DYNA magneto hydrodynamic modelling. The influence of geometrical defects is studied. To insure the success of this kind of test, the gap between electrodes must be tightly controlled. Electrodes must be machined with a tolerance lower than ten microns.

• New Features for Metal Forming in LS-DYNA

  X. Zhu, L. Zang (LSTC); B. Hochholdinger (DYNAmore Swiss)

• New Features in LS-DYNA EFG Method for Solids and Structures Analysis

  C. T. Wu - LSTC

  In this presentation, an update on LS-DYAN EFG method for solids and structures analysis will be given. Several features were developed in the past two years to solve specific challenging problems as well as to improve the efficiency. This talk will emphasize on three new features including an adaptive Meshfree scheme based on a local Maximum Entropy approximation for metal forging and extrusion analysis, a semi-Lagrangain formulation in foam materials under severe compression, and a discrete meshfree approach in the failure analysis of brittle materials. Several practical examples are included to demonstrate these capabilities.

• New Features in LS-DYNA EFG Method for Solids and Structures Analysis

  C. T. Wu - LSTC

  In this presentation, an update on LS-DYAN EFG method for solids and structures analysis will be given. Several features were developed in the past two years to solve specific challenging problems as well as to improve the efficiency. This talk will emphasize on three new features including an adaptive Meshfree scheme based on a local Maximum Entropy approximation for metal forging and extrusion analysis, a semi-Lagrangain formulation in foam materials under severe compression, and a discrete meshfree approach in the failure analysis of brittle materials. Several practical examples are included to demonstrate these capabilities.

• New Features in LS-DYNA HYBRID Version

  Nick Meng - Intel Corporation, Jason Wang, Satish Pathy - Livermore Software Technology Corporation

  Numerical noise arising from different MPP core counts compels users to fix the number of cores used by LS- DYNA® MPP e.g. during a vehicle development program. This fixed core count limits job turn-around time and flexibility in managing computing resources. In addition, using a large number of cores for calculations diminishes scalability with pure MPP. LS-DYNA® HYBRID addresses these issues through the use of both MPI + OpenMP technology. LS-DYNA HYBRID is able to produce consistent numerical results when changing the number of OpenMP threads thereby reducing job turnaround time. In addition, LS-DYNA HYBRID can greatly reduce the number of processors involved in message passing and achieve much better scalability over large number of cores. Furthermore, for the implicit applications LS-DYNA HYBRID not only reduces the memory requirement per node but also decreases IO activity. Currently, LSTC and Intel® teams are working together with a customer to evaluate LS-DYNA HYBRID code using a custom QA (Quality Assurance) suite. The consistency and performance will be discussed in this paper.

• New Features in LS-DYNA Part I

  J. Wang (LSTC)

• New Features in LS-DYNA Part II

  T. Erhart (DYNAmore), T. Borrvall (DYNAmore Nordic)

• New Features in LS-OPT Version 3.0

  Nielen Stander, Willem Roux - Livermore Software Technology Corporation

• New Features in LS-OPT® Version 3

  Nielen Stander, Willem Roux - Livermore Software Technology Corporation

  An overview of LS-OPT features is given with special emphasis on new features available in LS-OPT Version 3.1. The main features added to Version 3 include discrete optimization, 3-D metamodel plotting, additional statistics features, and a simplification of parameter identification. LS-OPT is now available for MS Windows®.

• New Features of CE/SE Compressible Fluid Solver in LS-DYNA®

  Zeng-Chan Zhang, Grant O. Cook, Jr. & Kyoung-Su Im (LSTC)

  CESE compressible fluid solver is one of the new solvers in LS-DYNA R7.0. This solver is based on the space-time conservation element and solution element (CE/SE) method, originally proposed by Chang [1]. The CE/SE method has many non-traditional features, such as (i) both local and global flux conservation are well maintained in space and time; (ii) shock waves can be captured automatically without using Riemann solvers or special limiters, etc. For more details about the CE/SE method, see the references [1, 2, 3]. This method is suitable for high-speed flows, especially with complex shock waves. In the past, the CESE method has been widely used in many different CFD-related areas, e.g., shock/acoustic wave interaction, detonation waves, cavitation, chemically reacting flows, etc.

• New Features of LS-PrePost 3.0

  Philip Ho - LSTC

  The introduction of the new LS-PrePost 3.0 will be presented here. A completely redesigned graphical user interface has been implemented in the new version of LS-PrePost 3.0. Tool bars and icons are being used for the main manual system to replace the old text based button system. The icons can be set to have text or without text. The new interface provides the maximum possible graphical area for the model rendering at the same time allow users to define their own toolbar with frequently used icons put together as they like. Besides using icons from the toolbars, a pull down manual system can also be used to reach to the function interfaces. Popup windows are used for each functional operation. Only one functional operational will be active at one time. Users can easily switch between the old and new interfaces if they do not feel comfortable in using the new interface. Also, an old to new interface button system has been implemented to transition users from the old interface to the new interface. Another major feature in LS-PrePost 3.0 is the newly developed geometry processing engine. The geometry processing engine is based on Open Cascade Technology 6.3. LS-PrePost 3.0 supports basic geometry entities such as lines, surfaces, and solids. It supports shape fixing and reshaping, such as fixing hole, small edge removal, vertex reposition and deletion, small face removal or face extension. It also supports faces stitching to provide better meshing result in the auto mesher. Geometry data can be imported via Iges or Step file format, while modified geometry also can be exported in iges file format. Surfaces can also be created from existing mesh using LSTC’s own reverse engineering module. Beside the new interface and geometry processing engine. New applications have been added to the LS-PrePost3.0 such as the Roller Hemming job setup and the LS-DYNA ALE job setup. An application frame work has been created such that new applications can be easily added in the future.

• New Features of LS-PrePost 3.0

  Philip Ho - LSTC

  The introduction of the new LS-PrePost 3.0 will be presented here. A completely redesigned graphical user interface has been implemented in the new version of LS-PrePost 3.0. Tool bars and icons are being used for the main manual system to replace the old text based button system. The icons can be set to have text or without text. The new interface provides the maximum possible graphical area for the model rendering at the same time allow users to define their own toolbar with frequently used icons put together as they like. Besides using icons from the toolbars, a pull down manual system can also be used to reach to the function interfaces. Popup windows are used for each functional operation. Only one functional operational will be active at one time. Users can easily switch between the old and new interfaces if they do not feel comfortable in using the new interface. Also, an old to new interface button system has been implemented to transition users from the old interface to the new interface. Another major feature in LS-PrePost 3.0 is the newly developed geometry processing engine. The geometry processing engine is based on Open Cascade Technology 6.3. LS-PrePost 3.0 supports basic geometry entities such as lines, surfaces, and solids. It supports shape fixing and reshaping, such as fixing hole, small edge removal, vertex reposition and deletion, small face removal or face extension. It also supports faces stitching to provide better meshing result in the auto mesher. Geometry data can be imported via Iges or Step file format, while modified geometry also can be exported in iges file format. Surfaces can also be created from existing mesh using LSTC’s own reverse engineering module. Beside the new interface and geometry processing engine. New applications have been added to the LS-PrePost3.0 such as the Roller Hemming job setup and the LS-DYNA ALE job setup. An application frame work has been created such that new applications can be easily added in the future.

• New Finite Element Model for NHTSA Impact Barrier

  Mehrdad Asadi - Cellbond Composites Ltd., UK, Brian Walker - Arup, Hassan Shirvani - Anglia Ruskin University, UK

  The US Federal Standard for Side Impact Protection (FMVSS 214) uses a deformable barrier and defines the dimensions and materials of the barrier, as well as the crush strength of the aluminium honeycomb parts in the main block and the bumper. This deformable barrier is also used for rear impact according to the updated FMVSS 301. This paper represents the methodology to create the advanced Finite Element model of Cellbond’s NHTSA barrier and validation through experimental test data. The explicit LS-DYNA® was used to analyze the model while number of static compressive tests performed at different angles to characterize aluminum honeycomb Material Cards. A strain-rate scale factor curve is defined to simulate the dynamic stiffening in the aluminium honeycomb during the analysis. Adhesive properties are also obtained using Climbing Drum, T-Peel, Tensile and Plate Shear test results. The preliminary component tests generated a good correlation with FE outputs and to validate the barrier model, similar impact tests were performed in LS-DYNA environment respecting to three experiments Flat-Wall, Rigid-Pole and Rear-Armature tests. In all assessments, the barriers were mounted on a moving trolley and were tested at certain speeds. The Final comparison on overall results represents a good correlation between test data and CAE results for all tests.

• NEW FORMULATION FOR COMPOSITE SANDWICH SHELL FINITE ELEMENT

  Romil Tanov, Ala Tabiei - University of Cincinnati

  A new homogenization procedure for Finite Element (FE) analysis of sandwich shells was recently developed and presented by the authors. To the authors’ knowledge all present FE approaches to sandwich structures are incorporated into the FE formulation on the element formulation level. Unlike other formulations the present approach works on the constitutive level. A homogenization of the sandwich shell is performed at each call of the corresponding constitutive subroutine. Thus the sandwich nature of the problem is hidden from the main FE program. As a consequence there is no need to develop a new shell element formulation, but instead all available homogeneous shell elements in the utilized FE code can be used for the analysis of sandwich shells. This would provide versatility of the FE analysis and potentials to trade off between the level of accuracy and computational efficiency by using more accurate or simpler shell elements. Furthermore, the sandwich homogenization procedure (SHOP) can be easily coupled with a composite homogenization model to enable analysis of sandwich shells with composite faces. To validate the present approach and check its accuracy, efficiency and overall performance it is implemented in a finite element package and combined with existing first order shear deformable shell elements for homogeneous materials. Results are obtained and herein presented for problems previously investigated experimentally and by different theoretical and numerical techniques. The presented results show good agreement with published results from far more complicated and computationally intensive analyses, which builds confidence in the approach and motives its future elaboration and development.

• New Generation Iterative Solvers in LS-DYNA®

  Cleve Ashcraft, Roger Grimes, Robert Lucas, François-Henry Rouet (Livermore Software Technology)

  Iterative solvers for sparse linear systems are used as the default option in a few places in LS-DYNA, e.g., thermal analysis and incompressible fluid flow. They are also available as a non-default option for implicit mechanics, electromagnetics, and acoustics. Until now, our suite of iterative solvers was limited to a few simple solvers (Conjugate Gradients and GMRES), and a few simple preconditioners. We recall that a preconditioner is an approximate inverse of the matrix (e.g., the stiffness matrix) that aims at improving convergence. Our preconditioners were limited to simple techniques like diagonal scaling and basic domain decomposition techniques that discard the coupling terms between processors, in MPP. Problems from customers are growing faster than memory size, making it difficult to use direct solvers. They are also often too numerically challenging to use simple iterative solvers, in particular in implicit mechanics. This has pushed us to revisit our suite of iterative solvers and preconditioners. In particular, we have been investigating the use of Block Low-Rank factorizations (BLR) and the use of Algebraic Multigrid (AMG). In the talk, we will compare these new options across all the different applications that make use of linear solvers. We will discuss convergence, memory usage, and scalability. For end users, the takeaway will be a better understanding of which solver options to use for different kinds of problems, and what to expect from them.

• New Generation Modeler for LS-DYNA Material Parameter Conversion

  H. Lobo, E. Strong, A. Beckwith (Matereality)

  We describe a new software component that takes into consideration the unique multi-variate nature of LS-DYNA material models. Rate-dependent models require adjustment and tuning of many material parameters to fit the rate-dependent tensile properties. Drawing upon a robust back-end data model, a graphical user interface provides drag and drop capability to allow the user to perform tasks such as model extrapolation beyond tested data, modulus change, rate dependency tuning and failure criteria adjustment while assuring self-consistency of the underlying material model. Unit system conversions are also facilitated, eliminating error and ensuring that material inputs to simulation correctly reflect the intent of the CAE analyst. The utility of the Matereality CAE modelers is illustrated with examples for LS-DYNA material models MAT_019, MAT_024 and MAT_089 LCSR.

• New Implementation of a Weakly Thermal-Mechanical Coupling Scheme in LS-DYNA®

  Thomas Kloeppel (DYNAmore GmbH)

  In this paper a novel implementation of a weakly one-way coupled approach for thermal-mechanical coupled problems is intro-duced. The core of the implementation is the new keyword *LOAD_THERMAL_BINOUT. The main advantage is a very flexible input structure, which allows defining the results of several thermal simulations, for example the temperature evolution in different weld stages, as time-dependent boundary conditions for a structural simulation. The temporal order, in which the temperature boundary conditions are processed, can easily be modified. Hence, the effect of, for example, a modified weld order can be considered without recalculation of the thermal results. Several examples will demonstrate the application and advantages of the new approach in the context of the manufacturing process chain. Limitations of the approach, further possible simplifications for coupled simulations and future implementations are also discussed.

• New LS-DYNA Fluids Solvers

  Grant O. Cook, Zeng-Chan Zhang - Livermore Software Technology Corporation

  This paper discusses two new fluid solvers that will be included with releases of LS-DYNA after LS960. The first one is a new compressible solver based upon the Space-Time Conservation Element and Solution Element Method (or the CE/SE method for short), and the second one is an incompressible fluid FEM solver.

• New material modeling approaches for thermoplastics, composites and organic sheet

  Matthias Vogler (Consulting engineer, Germany)

  In this paper, new anisotropic elastic-viscoplastic constitutive models for simulating thermoplastic materials, endless fiber reinforced composites and organic sheets are presented. The anisotropic material models address the same main features as the isotropic SAMP model (MAT_187 in LS-DYNA). These are in particular pressure dependent yielding allowing for different yielding in tension, compression, shear and biaxial loadings, tabulated input of hardening data for each stress state and a non-associated flow rule for a correct prediction of the volumetric plastic strains. Hence, the anisotropic material models represent a consistent further development of the isotropic SAMP material model (SAMP-1 or MAT_187 in LS-DYNA 971). ) The anisotropy is incorporated by an invariant formulation using structural tensors. This provides interesting modeling techniques for short fiber reinforced thermoplastics and for organic sheets. When modeling short fiber reinforced thermoplastics, the fiber orientation tensor is directly integrated into the constitutive equations and an automated homogenization is performed. That is, the fiber orientation tensor “weights” the structural tensors representing the preferred directions and in the limiting case “all fiber directions equally distributed in all directions”, the isotropic SAMP model is recovered as a special case. When modeling organic sheets, the finite fiber rotations observed under certain loading conditions can be simulated. That is, an initial misalignment of the yarns due to the draping process and also a loading induced misalignment of the yarns due to the forming process can be incorporated easily, letting the structural tensors rotate against each other. The applicability of the anisotropic material models will be shown with three examples. First, simulation results of a short fiber reinforced polymer PA6GF60 are presented. These are in particular the material characterization tests (tensile, compression and shear tests) and quasi-static and dynamic 4a-Impetus bending tests. Secondly, simulation results of quasi-static and dynamic off-axis compression tests of a carbon epoxy IM7-8552 are presented, predicting the experimentally observed pre-failure nonlinearities. Finally, the applicability of the anisotropic model to organic sheets is discussed. The experimentally observed highly non-linear behavior under shear dominated loadings due to the finite fiber rotations and the quasi brittle behavior in uniaxial tension and compression in the main directions can be predicted. In future developments, the whole process chain drape simulation, forming simulation and crash simulation will be addressed.

• New Metal Forming Keywords in LS-DYNA®

  Xinhai Zhu, Yuzhong Xiao, Jin Wu (Livermore Software Technology, an ANSYS Company)

  Newly developed forming keywords have been optimized to be easy for users. Besides the unification of all the control cards, the tool motion definition has been simplified dramatically and time-related tooling motion curve definition is no longer needed. Various contact algorithm parameters are also treated internally by the LS-DYNA solver. More realistic contact features are available to simulate draw beads and pins. New metal forming keywords therefore achieve an input deck with well-organized input formats which directly describe actual forming processes.

• New Method to Characterize Airbag Inflators On the Way to OoP Simulation

  Juan Fernández - Takata-Petri AG

  An accurate Out-of-Position (OoP) simulation will be a mile stone for the development of restraint systems, as this would save hundreds of expensive hardware tests. OoP load cases are currently required by the US legislation and as in-house specification by many car manufactures for other markets. But simulating OoP is a difficult issue, as several challenges have to be addressed, for example: An improved dummy model validated against new component tests and an accurate modeling of the folding/unfolding of an airbag including an appropriate gas model. One of the missing pieces for this simulation is the accurate representation of the inflator mass flow. The current method to characterize gas inflators is the tank test. This method has big advantages, being cheap, reproducible and independent of the inflator geometry. The tank test shows, however, some important drawbacks: The lack of similarity of the bag inflation regarding volumetric work of the gases and initial conditions, a uniform and immediate pressure distribution must be assumed, the measurement –tank pressure– must be derived to obtain the inflator gas mass flow resulting in a higher measurement error and heat losses are high and not uniform during the process.

• New Method to Characterize Airbag Inflators On the Way to OoP Simulation

  Juan Fernández - Takata-Petri AG

  An accurate Out-of-Position (OoP) simulation will be a mile stone for the development of restraint systems, as this would save hundreds of expensive hardware tests. OoP load cases are currently required by the US legislation and as in-house specification by many car manufactures for other markets. But simulating OoP is a difficult issue, as several challenges have to be addressed, for example: An improved dummy model validated against new component tests and an accurate modeling of the folding/unfolding of an airbag including an appropriate gas model. One of the missing pieces for this simulation is the accurate representation of the inflator mass flow. The current method to characterize gas inflators is the tank test. This method has big advantages, being cheap, reproducible and independent of the inflator geometry. The tank test shows, however, some important drawbacks: The lack of similarity of the bag inflation regarding volumetric work of the gases and initial conditions, a uniform and immediate pressure distribution must be assumed, the measurement –tank pressure– must be derived to obtain the inflator gas mass flow resulting in a higher measurement error and heat losses are high and not uniform during the process.

• New Methods for Compression Molding Simulation and Component Strength Validation for Long Carbon Fiber Reinforced Thermoplastics

  S. Hayashi (JSOL), C.T. Wu, W. Hu, Y. Wu, X. Pan, H. Chen (LSTC)

  Composite materials like fiber reinforced plastics (FRP) are becoming more widely used in the automotive industry and have been found very effective in reducing vehicle weight. Recently, long carbon fiber reinforced thermoplastics are increasingly being used for lightweight structural parts with high stiffness, strength and energy absorption performance. Compression molding is considered one of the most efficient manufacturing processes to mass produce FRP parts for automotive applications. Compression molding can form FRP into complex shapes with relatively low manufacturing cost and short process time. However, this often generates unwanted fiber orientation, uneven distribution of fibers and fillers, weld lines and matrix rich regions. These forming effects strongly affect mechanical strength. To analyze these complex phenomena, LSTC and JSOL developed new compression molding simulation techniques for long fiber reinforced plastics using a beam-in-adaptive EFG coupling function in LS-DYNAⓇ. In this paper, a compression molding simulation for long carbon fiber reinforced thermoplastics is introduced and new component strength analysis method with a beam-in-SPG coupling model using deformed beams calculated in the compression molding simulation is presented.

• NEW NONLINEAR HIGHER ORDER SHEAR DEFORMATION SHELL ELEMENT FOR METAL FORMING AND CRASHWORTHINESS ANALYSIS: PART I. FORMULATION AND FINITE ELEMENT EQUATIONS

  Ala Tabiei, Romil Tanov - University of Cincinnati

  This work presents the finite element formulation of a higher order shear deformation shell element for nonlinear dynamic analysis with explicit time integration scheme. A corotational approach is combined with the velocity strain equations of a general third order theory in the formulation of a four- noded quadrilateral element with selectively reduced integration. A bilinear isoparametric formulation is utilized in the shell plane resulting in 9 degrees of freedom per node. The formulation requires C0 continuity for the nodal variables. The finite element implementation of the new element in a general explicit finite element code is described in details, including boundary conditions and nodal mass calculation. A simple formula for the explicit time integration critical time step of the higher order element is developed. The described element is capable of correctly representing the through thickness distribution of the transverse shear, which makes it suitable for composite and sandwich shells analysis. In addition, the developed shell can be used for better representation of plastic flow through thickness in isotropic materials. It has been added to the element library of the nonlinear explicit finite element code DYNA3D. Its performance has been evaluated through a series of standard shell verification test problems, which show great promise for many applications. The results are presented in Part II of the present work.

• NEW NONLINEAR HIGHER ORDER SHEAR DEFORMATION SHELL ELEMENT FOR METAL FORMING AND CRASHWORTHINESS ANALYSIS: PART II. PERFORMANCE VALIDATION THROUGH STANDARD TESTS

  Ala Tabiei, Romil Tanov - University of Cincinnati

  This work presents the results from a set of verification shell problems used to assess the performance of the higher order shear deformation shell elements formulated in part I of the present study. The developed element has been added to the element library of the nonlinear dynamic explicit finite element code DYNA3D. Several standard verification test problems are performed using the code DYNA3D with the developed shell element. Results are presented for different test problems and are compared with experiments and results from other existing shell elements. The good overall performance builds confidence in the formulation and implementation of the proposed higher order shear deformable element. The superior advantage of the developed element is evident in one of the examples presented for representation of plastic flow through the thickness in isotropic materials. The element can be used in crash and metal forming simulations in local areas of high transverse shear stresses. Local areas of crack in crash applications and splitting in metal forming applications can be modeled more accurately with the developed shell element. Key words: nonlinear higher order shear deformation shell elements, explicit finite element analysis, shell verification test problems, shell element performance

• New Options in Frequency Domain Analysis and Fatigue Analysis with LS-DYNA

  Y. Huang (LSTC)

  A series of frequency domain analysis and fatigue analysis features have been implemented to LS-DYNA, since version 971 R6 [1]. The frequency domain features include FRF (Frequency Response Function), SSD (Steady State Dynamics), random vibration, response spectrum analysis, and acoustic analysis based on BEM (Boundary Element Method) and FEM (Finite Element Method). The fatigue analysis features include fatigue damage solvers in both time domain and frequency domain (based on random vibration and steady state vibration). The main applications of these features are in NVH and durability analysis of structures and components [2]. A bunch of new options were implemented to the frequency domain analysis and fatigue analysis features since the last European LS-DYNA Conference in Salzburg, Germany, 2017.

• New Ordering Method for Implicit Mechanics and What It Means for Large Implicit Simulations

  Roger Grimes, Cleve Ashcraft (LSTC)

  The most egregious serial bottleneck for Large Implicit Mechanics modeling for distributed memory parallel execution, independent of the application package, is the sparse matrix ordering for the direct matrix solution. LSTC is developing a new distributed memory ordering algorithm that is at least as effective as the serial algorithm METIS but is a fully scalable implementation. We will give an overview of the algorithm and the impact on some benchmark problems.

• New Representation of Bearings in LS-DYNA®

  Kelly S. Carney, Samuel A. Howard (NASA Glenn Research Center), Brad A. Miller (Harding University, Searcy), David J. Benson (University of California San Diego, La Jolla)

  Non-linear, dynamic, finite element analysis is used in various engineering disciplines to evaluate high-speed, dynamic impact and vibration events. Some of these applications require rotation of some elements relative to other elements with various levels of constraints.  For example, bird impacts on rotating aircraft engine fan blades is a common analysis done using this type of analysis tool. Traditionally, rotating machines utilize some type of bearing to allow rotation in one degree of freedom while offering constraints in the other degrees of freedom.  Many times, bearings are modeled simply as linear springs with rotation.  This is a simplification that is not necessarily accurate under the conditions of high-velocity, high-energy, dynamic events such as impact problems. For this reason, it is desirable to utilize a more realistic non-linear force-deflection relationship characteristic of real bearings to model the interaction between rotating and non-rotating components during dynamic events.  The present work describes a rolling element bearing model developed for use in non-linear, dynamic finite element analysis. This rolling element bearing model has been implemented in LS-DYNA as a constraint, *CONSTRAINED_BEARING.

• New Technologies for Side Impact Model Set-Up

  T. Fokylidis, A. Lioras (BETA CAE Systems)

  During the development and design process of a vehicle, Occupant protection in side impact studies has become a standard analysis. One of the most important issues that analysts face in side impact is how the passenger’s seat and the dummy will be adjusted in the proper position for the laboratory tests. This makes the application of numerical simulations inevitable. Simultaneously, as new legal tests and regulations are continuously introduced, the amount of relative loadcases has increased dramatically.

• New Testing in Support of LS-DYNA MAT 224 Material Model

  A. Gilat, J. Seidt, N. Spulak, J. Smith (Ohio State University)

  LS-DYNA MAT224 is a tabulated plasticity and failure model. The plasticity part of the model can include strain rate, strain hardening and temperature effects, and the failure part is based on a failure surface of the equivalent plastic strain to failure as a function of triaxiality and the Lode parameter. The present paper presents two new experiments that have been developed recently in order to support the model. The first experiment adds new points to the failure surface in a region that is important in simulations of projectile impact and penetration. The second experiment is used for determining the Taylor-Quinney coefficient (β), which controls the magnitude of the temperature increase due to plastic deformation. Simulations of impact and penetration events show that failure occurs under a stress state of biaxial tension and out-of-plane compression. This state of stress on the failure surface is not in the region that is populated with data points obtained from typical experiments (tensile tests of flat and round, parallel and notched specimens, tensile tests of wide parallel and notched specimens, pure shear tests, combined tension-compression/shear tests, and compression tests.) In order to obtain an independent measurement of the equivalent strain to failure under a state of stress of biaxial in-plane tension and out-of-plane compression a new experiment was developed. In this experiment a small diameter punch penetrates a thin specimen plate that is backed by another plate. The deformation of the back surface of the plate is measured with DIC. The value of the equivalent strain to failure is determined from measuring the force and matching the LS-DYNA simulation with the measured deformation and force.

• New XY-Plot interface in LS-PrePost ®

  Philip Ho, Luo Liangfeng, Wenhui Yu, Satish Pathy (LSTC)

  LS-PrePost, a pre and post processing program that compliments LS-DYNA ® , was lacking a good XY-Plotting tool. This paper illustrates and describes the new XY-PLOT which will make post-processing of results an efficient task. With the use of templates, plots from historical data can be generated quickly and compared with the current results. This paper discusses software architecture, its implementation and functionalities. It also discusses future work and direction.

• Newly Developed Capabilities of DYNAFORM Version 5.0

  Wenliang Chen, Dingyu Chen, H.Xie, Quanqing Yan, Arthur Tang, Chin Chun Chen - Engineering Technology Associates, Inc., USA

  Over the past two decades, the finite element analysis (FEA) has emerged as one of the most important engineering tools in the many industries, due to its flexibility and accuracy in prediction. Nowadays, it is widely used in sheet metal forming industry to predict the forming feasibility of wide variety of complex components, ranging from aerospace and automotive components to household products. As the demand of FEA accelerates, the need for a robust and streamlined process based pre-processor has become crucial, especially in the tool and die manufacturing industry. As a continuous effort, the DYNAFORM Version 5.0 has been developed to meet the needs. This paper will discuss the capabilities of two newly developed key features embedded in the DYNAFORM Version 5.0. These “state of the art” features are Quick Setup (QS) and Die Face Engineering (DFE) module. The QS module aims to reduce the setup time for stamping simulation, while the DFE module allows stamping engineers to create, re-design and reengineer the tooling from part geometry.

• Newly Developed LS-DYNA® Models for the THOR-M and Harmonized HIII 50th Crash Test Dummies

  Chirag S. Shah, Suraush Khambati, Brock Watson, Nishant Balwan, Zaifei Zhou, Fuchun Zhu, Shiva Shetty (Humanetics Innovative Solutions, Inc.)

  Finite Element (FE) models of Anthropomorphic Test Device (ATD), commonly known as crash test dummies, have become increasingly applicable in automotive safety. A variety of ATDs models are widely used in many areas such as restraint development, automotive crashworthiness, occupant safety and other automotive environment related applications. With the increase in cost effectiveness of computational power, progressively complex and detailed computer models of ATDs have become more realistic in recent years. There has been growing demand for these models due to the inherent benefits of reduced cost and time in the product development cycle. The presented paper highlights the development process of two of such highly detailed frontal impact ATD models namely: THOR-M 50th and Harmonized Hybrid III (HIII) 50th in the LS-DYNA FE code. Both these dummy models represent anthropometry of a 50th percentile adult male. The current work describes the model development process and a controlled loading case for each of the dummies to illustrate the predictive capabilities of both models. The geometries and inertial properties for both dummy models are obtained from available drawings and hardware. The model connectivity and structural integrity are inspected by experiments and verified against hardware. Material tests have been conducted for all critical materials, enabling characterization using the latest material modeling techniques. The model’s material properties are implemented from physical test data after numerical parameter extraction and verification through coupon simulations, using available material cards. All the injury output sensors and instrumentation in these models are developed and implemented based on all possible instrumentation information in hardware. These models are then validated against a variety of component, sub-assembly, and full dummy level load cases, as a key for developing reliable models that meet industry expectations. A detailed validation case of the thorax is presented for the Harmonized HIII 50th and a neck validation case is presented for the THOR-M 50th dummy. The current development status has shown very reasonable predictive capabilities of these two models as evident in the illustrated loading conditions which range from component to full dummy level.

• Node to node contacts for SPH applied to multiple fluids with large density ratio

  Jingxiao Xu, Jason Wang (LSTC)

  The interesting and complex behavior of fluids emerges mainly from interaction processes. SPH has shown to be a simple, yet flexible method to cope with many fluid simulation problems in a robust way. However in SPH, particles have a spatial distance (smoothing length) over which their properties are smoothed by a kernel function. Smoothed quantities of a particles show falsified values when densities and masses of neighboring particles vary largely within the smoothing length. The erroneous quantities lead to undesirable effects, reaching from unphysical density and pressure variations to spurious and unnatural interface tensions, and even to severe numerical instabilities. In this paper, instead of using the traditional interaction between SPH parts through SPH interpolation, we present a node to node contact between different SPH parts to avoid the instabilities due to large density ratios at the interfaces. The methods allow the users to select the desired amount of contact force between two SPH parts by choosing the desired penalty scale factors according to the simulation problem at hand. Some examples are tested to show that the method was successfully used to stably simulate multiple fluids with large density contrasts without the above described artifacts apparent in standard SPH simulation.

• Non-Isochoric Plasticity Assessment for Accurate Crashworthiness CAE Analysis. Application to SAMP-1 and SAMP-Light

  P. Cruz, E. Martin-Santos, L. Martorell (Applus IDIADA) M. Lobdell, H. Lobo (Applus Datapointlabs)

  A deep understanding of advanced material plasticity and fracture is one of the cornerstones of mechanical engineering to overcome present and future challenges in the automotive industry with respect to lightweight multi-material body solutions. The von Mises plasticity model is well-known and efficiently implemented in the various CAE solvers conventionally used in the automotive industry. One of the principal characteristics of the von Mises model is the assumption of isochoric plasticity (i.e. no change of volume is caused by yielding). The literature and experiments show that some materials, like extruded aluminium or polymers, exhibit non-isochoric plastic behaviour. Since this effect cannot be captured by the von Mises plasticity model, an optimal design for lightweight structural solutions is compromised.

• Non-Linear Fracture Mechanics in LS-DYNA and LS-PrePost

  P. Lindström (University West/DNV GL Materials Laboratory), A. Jonsson, A. Jernberg (DYNAmore Nordic), E. Østby (DNV GL Materials Laboratory)

  In non-linear fracture mechanics, an energy based criterion is used for assessing the risk for crack growth: if the energy release rate at the crack tip exceeds what is required for creating new surfaces in the material, crack growth will occur. Under certain assumptions the energy release rate at the crack tip can be calculated by a path independent integral, the so-called J-integral.

• Non-Linear Time History Analysis of Tall Steel Moment Frame Buildings in LS-DYNA

  Carlos Molina Hutt (UCL)

  ® Non-linear time history analyses were carried out in LS-DYNA (LSTC) in order to assess the seismic performance of existing tall steel moment resisting framed buildings. Ground motion earthquake records representative of the Maximum Considered Earthquake (MCE) hazard level defined in current building codes were used in the analysis. This paper focuses on the different component models utilized to capture the complex non-linear elements of the structure: beams, columns, panel zones, splices and moment connections. Both beam and column elements were modelled using the Belytschko-Schwer element formulation with lumped plasticity at both ends of the resultant beam. Columns elements captured interaction between bi-axial bending moment and axial force, buckling in compression and degradation parameters for response under cyclic loads calibrated to match experimental tests results. Beams elements captured implicit degradation in bending and random fracture at the connections. The random fracture was modelled such that plastic rotation at fracture occurred as a random variable characterized by a truncated normal distribution following results from experimental testing. Panel zones and column splices were modelled with discrete elements and general nonlinear translational and rotational springs. Panel zones were modelled using the Krawinkler model by means of an assembly of rigid links and rotational springs to capture the tri-linear shear force-deformation relationship of the joint. Column splices were modelled as non-linear springs capable of reaching their nominal capacity with a sudden brittle failure in axial tension and/or bending and full capacity in compression as observed in experiments. The paper briefly discusses the limitations of complex analytical models in trying to capture the non-linear dynamic response of structural systems and components.

• Non-Penetrating Impact Simulation of Stitched Resin Film Infused Composites

  A. M. Floyd, R. Vaziri, A. Poursartip - The University of British Columbia

  The CODAM constitutive model has been implemented in LS-DYNA as a user-defined material model (UMAT). Using this material model, quasi-static over-height compact tension (OCT) tests on a stitched resin film infused (S/RFI) carbon/epoxy composite material were simulated, and the results demonstrated good agreement with the measured force and crack mouth opening displacement (CMOD). The same CODAM inputs were then used to simulate non-penetrating impact events on the S/RFI material. The simulations successfully predicted the peak force and event durations for targets oriented in one direction, but under-predicted the peak force and over-predicted the event duration for the opposite target orientation.

• Non-Structural Mass Modeling in Aircraft Impact Analysis using Smooth Particle Hydrodynamics

  M. Kostov, M. Miloshev, Z. Nikolov, I. Klecherov (Risk Engineering)

  The non-structural mass in the large commercial airliners includes fuel, cargo, passengers, luggage, seats, lockers, etc. The straightforward approach for modelling of this non-structural mass is to include it as additional mass density to the corresponding structural elements. This approach would lead to conservative results in case of impact as the non-structural mass remains attached to the aircraft for the entire duration of the calculation, resulting into an overestimated impact effects. Alternative approach for modelling of non-structural mass is the application of the Smooth Particle Hydrodynamics (SPH) method.

• Nonlinear Analysis 1980 - 2020

  M. Lawson (Rolls-Royce)

• Nonlinear Analysis of Copper Water Stop

  Lou Pingyi, Cao Deqing - Beijing Engineering Software Technology Co. Ltd.

  Copper water stop is used to prevent water seeping through the dam. To get the stress and strain distribution status of water stop, LS-DYNA was used to make a nonlinear analysis. Experiment results and simulation data were tested to be consistent.

• Nonlinear Crash Dynamics Simulation of Novel Airbag Based Next Generation Energy Absorbing Barrier

  Dr. Rahul Gupta, Dr. Ajit D. Kelkar - North Carolina A & T State University

  The fatality analysis report system of the National Highway Traffic Safety Administration reported that approximately 42,000 people in the United States are killed annually in motor vehicle crashes. Approximately 30 percent of the fatalities are from run-off-the-road crashes involved in collisions with roadside objects. Energy absorbing barriers (EABs) such as concrete median barriers, guardrails, guardrail end treatments, impact attenuators, crash cushions and bridge rails are designed to absorb and dissipate the kinetic energy of run-off-the- road vehicles efficiently. The main purpose of EABs is to increase vehicle occupant survivability while reducing injury levels by smoothly redirecting an errant vehicle to bring it to a controlled stop and to prevent deadly rollover or crossover accidents. Non-linear, three-dimensional, FEA code LS-DYNA is used to perform realistic and predictive virtual crash simulations for analyzing the large-deformation dynamic responses of elastic or inelastic structures using implicit as well as explicit time integration schemes. This paper presents a novel airbag technology, fluid-structure interaction effect based patented EAB designed and tested by the researchers at North Carolina A&T State University primarily for high velocity impacts. Simulation and testing have shown marked improvements compared to the current generation of EABs. The analysis consists of a crash deformation profile, acceleration records at different locations, and energy absorptions by different components.

• Nonlinear Finite Element Analysis of Airport Approach Lighting Structures under Impact Loading

  M. Nejad Ensan, D.G. Zimcik - National Research Council Canada, S.T. Jenq, F.B. Hsiao - National Cheng Kung University, Taiwan

  This paper describes computer simulation of the impact of airport approach lighting structures using the LS-DYNA nonlinear finite element analysis (FEA) software. Two tower designs were investigated in this simulation. First, a finite element model (FEM) was developed to simulate the impact of a representative tower typical of those used at Canadian airports. This was 6.6 m tall tower with a triangular cross section made of aluminum. The analysis simulated an aircraft wing striking the tower triangular cross section 1 m from the top in two different orientations of the tower, at the apex and on the side. Top mass of 2.72 kg or 5.44 kg, representative of lights and/or light fixtures was included in the model which was impacted at three different impact velocities: 50, 80 and 140 km/h. Further simulation was carried out on a second model of an approach light masts with different geometry and made of a different material typical of those used at some European airports. These were 6 m tall masts, and contained a dummy top mass of 15 kg, simulating the effect of a cross-bar with three approach lights. The masts were configured as a composite lattice structure with a square cross section made of glass/epoxy. The impact of the mast at a height of 4.1 m above the ground due to an impact of the moving aircraft wing at velocity of 140 km/h was simulated. The duration of the simulation in both cases was 100 milliseconds to captured the phase in which most of the damage to the tower took place. Simulation results were used to predict the deformation mode and magnitude, location and timing of failure, impact force and energy absorption curves as a function of time during the impact. These results were compared to experimental data from full-scale tests to validate the accuracy of the models. These data were necessary for the development of simplified requirements and test methods for the design of frangible structures that minimize the impact hazard to aircraft.

• Nonlinear viscoelastic modeling for foams

  Veronika Effinger, André Haufe (Dynamore GmbH), Paul DuBois (Consultant), Markus Feucht (Daimler AG), Manfred Bischoff (University of Stuttgart)

  Lightweight design is one of the major principles in automotive engineering and has made polymer materials to inherent parts of modern cars. In addition to their lightweight potential thermoplastics, elastomers, fabric and composites also incur important functions in passive safety. In the age of virtual prototyping, assuring these functions requires the accurate modeling of the mechanical behavior of each component. Due to their molecular structure, polymer materials often show viscoelastic characteristics such as creep, relaxation and recovery. However, considering the general state of the art in crash simulation, the viscoelastic characteristics are mainly neglected or replaced by viscoplastic or hyperelastic and strain rate dependent material models. This is either due to the available material models that are often restricted to linear viscoelasticity and thus cannot model the experimental data or due to the time consuming parameter identification. In this study, a nonlinear viscoelastic material model for foams is developed and implemented as a user material subroutine in LS-DYNA®. The material answer consists of an equilibrium and a non-equilibrium part. The first one is modeled with a hyperelastic formulation based on the work of Chang [1] and formerly implemented as *MAT_FU_CHANG_FOAM in LS-DYNA (*MAT_083). The second one includes the nonlinear viscoelastic behavior following the multiple integral theory by Green and Rivlin [2]. The polyurethane foam Confor® CF-45 used as part of the legform impactor in pedestrian safety was chosen for its highly nonlinear viscoelastic properties to test the presented approach. The investigation shows the ability of the method to reliably simulate some non-linear viscoelastic phenomena such as saturation.

• Novel HPC Technologies for Scalable CAE: The Case for Parallel I/O and File Systems

  Stan Posey - Panasas, Inc., Fremont, CA, USA

  As HPC continues its aggressive platform migration from proprietary supercomputers and Unix servers to HPC clusters, expectations grow for clusters to meet the I/O demands of increasing fidelity in CAE modeling and data management in the CAE workflow. Cluster deployments have increased as organizations seek ways to cost- effectively grow compute resources for CAE applications, and during this migration many also implemented conventional network attached storage (NAS) architectures to simplify IT administration and further reduce costs. While legacy NAS implementations offer several advantages of shared file systems, most are too limited in scalability for effective management of I/O demands with parallel CAE applications. As such, a new storage migration is underway to replace legacy (serial) NAS with parallel NAS architectures and parallel file systems. This new class of parallel file system and shared storage technology was developed to scale I/O in order to extend the overall scalability of CAE simulations on clusters. This paper examines CAE motivation for shared parallel file systems and storage, for requirements of multi-physics LS-DYNA® applications on conventional clusters with proper balance for I/O. Model parameters such as size, element types, schemes of implicit and explicit (and coupled), and a variety of simulation conditions can produce a wide range of computational behavior and I/O data management demands. The benefits of a Panasas storage implementation are introduced for such broad requirements, through examples of CAE workflows for a variety of production-level applications in industry.

• Novel Multi-scale Modeling of Woven Fabric Composites for use in Impact Studies

  Gaurav Nilakantan, Michael Keefe, John W. Gillespie Jr. - University of Delaware, Travis A. Bogetti - US Army Research Laboratory

  A novel approach to the multi scale modeling of the impact of woven fabrics using LS-DYNA® has been presented. This new technique entitled ‘Hybrid Element Analysis (HEA)’ incorporates the use of different finite elements at both a single and multiple level of modeling. A yarn level resolution is maintained around the impact zone or local region, while a homogenized resolution has been used for the far field or global region. The central patch of yarn level resolution uses a combination of solid and shell elements. A new method for modeling individual yarns using shell elements is discussed, which more accurately captures the geometrical contours of the yarn cross section. The surrounding homogenized zone uses shell elements. Interfaces using various types of tie-constraints are created between the different finite elements at the various scales of modeling. The acoustic impedances have been matched across the interfaces. A systematic approach is presented to determine the geometric and material parameters of the homogenized zone. The HEA approach maintains the accuracy of using a fabric model comprised entirely with yarn level resolution utilizing solid elements, but at a fraction of the computational expense. This enables the finite element simulation of multi layered fabric systems with very large domains, which was previously very difficult because of the impractical computational requirements of such an exceedingly large model. Compared to previous numerical multi-scale models, the finite element model using the HEA approach presented in this paper more accurately captures the entire impact event at a lower computational expense, making it a very useful tool for future studies.

• Novel Simulation of Composite Material behavior Subjected to Hyper-Velocity Impact (HVI) and Produced Secondary Debris by using Smoothed Particle Hydrodynamics Code (SPH) Methodology in LS-DYNA

  E. Giannaros, Prof. A. Kotzakolios, S. Tsantzalis, V. Kostopoulos (University of Patras); G. Campoli (ESA /ESTEC)

  The escalating usage of composite materials to improve fuel efficiency while reducing the structural mass of satellites and manned spacecrafts has become high priority target to the space industry. On the other hand, high moving space debris such as old satellites, spent rocket stages and fragments from collision can devastate the composite structures producing thousand secondary debris. Therefore, the prediction of impact behavior of composites and the distribution of ejecta using high-technology simulation tools are essential and vital since the experimental investigations on this field is extremely limited due to the difficulty of tests. The classical simulation technique implementing finite elements constitutes a robust numerical method for various static and dynamic problems, but its major problem is the difficulty to handle the large distortion of elements in fast-transient dynamics problems and the inability to simulate the secondary debris distribution. In past, several studies for isotropic materials impact behavior using the meshless SPH methodology of LS-DYNA code have been presented, nevertheless the simulation of composite material behavior subjected to hyper-velocity impact using SPH in LS-DYNA is missing from the literature. In the present work, a novel validation procedure for the proper modeling of a composite laminate to hyper-velocity impact loading using SPH methodology is proposed. Simultaneously, the influence of major parameters of SPH methodology on results of simulations are assessed. The study starts with some baseline static tests (in-plane tension of an unidirectional composite, in-plane tension of multi-layer [45/-45]4s composite laminate, out-of-plane shear test and out-of-plane compression test) whose results are compared with finite element method results and theoretical ones in order to ensure the efficiency of the hydrodynamic code. In final validation step of this study, literature experimental tests for composite laminate response subjected to HVI are numerically reproduced. Comparing the numerical and experimental ballistic limit, crater diameter as well as the ejecta distribution, the effectiveness and the limits of SPH methodology of LS-DYNA code for composite materials are evaluated.

• Numerical Analysis of Impact Tests on Bending Failure of Reinforced Concrete Slabs Subjected to Inclined Soft Missile Impact

  C. Heckötter, J. Sievers (GRS)

  Impact loading is a safety relevant loading case for reinforced concrete structures used to protect vital parts of nuclear facilities. Numerical methods used for the assessment are validated on the basis of impact tests. Even though normal impacts are the most common item of analysis, special issues are related to inclined impact. Effects of inclined impact include slipping and rotation of the missile, motion of the impact point and effects of tangential forces. Recently, an experimental program dealing with bending failure of reinforced concrete slabs subjected to inclined soft missile impact was carried out at Technical Research Centre of Finland (VTT) in the frame of phase IV of the international research project IMPACT. This paper reports on simulation results on these tests using LS-DYNA.

• Numerical Analysis of Multistep Ironing of Thin-Wall Aluminium Drawpiece

  L. Brodawka, M. Kociolek, M. Siedlik, R. Budzyn, A. Furman (Can-Pack), A. Rekas, T. Latos (AGH University of Science and Technology)

  This work presents results obtained from numerical analysis of ironing with use of finite element mesh. The base drawpiece, that was a starting point in the analysis, includes a full history of deformation that resulted from simulations of preceeding operations, that is drawing and redrawing. Such a complex approach allows for a complete analysis of each successively conducted process. In the case of materials of thicknesses smaller than 0.

• Numerical Analysis of Relationship between Height and Geometry of Bottom of a Beverage Can and its Resistance to Increase in Internal Pressure

  L. Brodawka, M. Kociolek, M. Siedlik, R. Budzyn, M. Fijalkowski (Can-Pack), T. Latos, A. Rekas (AGH University of Science and Technology)

  Dome reversal pressure test is one of crucial quality tests required of such products as beverage cans. It gives information about resistance of a bottom in conditions of increased internal pressure. The information is important both for producers of carbonated beverages and final users. The test identifies the maximum internal pressure, which does not cause reversal buckling of a dome.

• Numerical Analysis of the Effects of Orthogonal Friction and Work Piece Misalignment during an AA5042 Cup Drawing Process

  Allen G. Mackey (Rigid Packaging Division)

  Wrinkle development during cup drawing operations is known to be highly dependent on many variables, including material anisotropy, tool geometry, process parameters, and tooling alignment. Weight reduction efforts in packaging industries have resulted in decreasing metal gauges, which exacerbates the formation of wrinkles. In this study, the Numisheet 2014 Benchmark 4 cup drawing process is used to investigate the effects of orthogonal friction on wrinkle formation during drawing of an AA5042 aluminum cup. The anisotropic material properties of rolled AA5042 aluminum alloy sheet are implemented as specified in Numisheet Benchmark 4 for accuracy. The coefficient of friction of the rolled sheet blank is examined orthogonally. The effects of work piece misalignment are investigated and compared to ideal results. Furthermore, the effect of orthogonal friction on the punch force is examined.

• Numerical and Experimental Correlation of a Survival Cell Designed for a Bus Body Structure

  F. Biondo, A. Sordi, G. Magnabosco (Marcopolo)

  The behavior of mechanical structures, when subjected to impact load, is a matter of great relevance and its applications in terms of vehicle collision. When we analyze the superstructure of a bus, those vehicles must be tested according to prerequisites established in standards such as UNECE ECE 29 (European standard) or CONTRAN 629/2016 (Brazilian standard). The standards prescribe to use a pendular system to evaluate the frontal structure of the vehicle. In this regulation is defined the height and the mass that will collide with the structural modulus. However, the procedures described in these standards do not represent the real collisions involving these types of vehicles. This can be seen when comparing the energy imposed on the test module, detailed in CONTRAN 629/2016, where the energy imposed on the vehicle is approximately 20 kJ on each side of the test module, this corresponds to a collision of a 5 tons vehicle at 10 km/h or a 20 tons bus at 5 km/h.

• Numerical and Experimental Study on Fracture of Chute Structure at Deployment of Invisible Passenger Side Airbag

  L. Kangwook - Hyundai Mobiles

• Numerical and Experimental Determination of Strains in the Vicinity of a Centrally Located Circular Discontinuity in AA6061-T6 Square Extrusions during Axial Crushing

  Neil Turton, Amitabha Majumder, William Altenhof, Daniel Green, Vivek Vijayan, Honggang An,Shun Yi Jin - University of Windsor, Canada

  An experimental and numerical investigation was conducted on AA6061-T6 extrusions with centrally located through-hole discontinuities to investigate the strains in the vicinity of the crush trigger. The extrusions used in this research were of square cross sectional geometry with a nominal side width of 38.1 mm, wall thickness of 3.15 mm and length of 200 mm. Centrally located circular discontinuities with a diameter of 14.29 mm were incorporated into the extrusion through CNC machining. The axial crushing tests were performed in a quasi-static manner using a hydraulic Tinius-Olsen tension/compression testing machine and observed using a GOM Aramis optical strain measuring device focusing on the region in the vicinity of the discontinuity. A finite element model previously developed by Arnold and Altenhof was selected to compare strains in the region of the through-hole. The material definition for the AA6061-T6 extrusion utilized in this FE model incorporated damage mechanics theory which was able to accurately predict material failure after a two-stage calibration process. All simulations considered in this research were completed using LS-DYNA® version 970 revision 5434a. Good predictive capabilities of the strain magnitudes and distributions were observed from the numerical simulations. In the vicinity of the discontinuity, at the stress concentration region and at maximum crushing force, the effective strain was observed to range from 4.5% to 15.5% in LS-DYNA simulations. Experimental observations on the effective strain ranged from 5.0% to 15.7%. This information is important in the understanding of large deformation behaviour for AA6061-T6 extrusions, which could be applied in structural crashworthiness applications.

• NUMERICAL AND EXPERIMENTAL STUDY OF SAFETY NET SYSTEMS FOR HUMAN AND EQUIPMENT SECURITY (SKI APPLICATION)

  BEN YAHIA Fayçal - DYNALIS, GOURINAT Yves - ENSICA

  Human and material safety systems evolve continuously to become more perfect and face increasing requirements. Indeed, important changes of usage conditions and precautions have been caused by the technological progress of the various domains of life (means of transportation, sporting equipments etc.). In order to follow this technological expansion and optimize it for the benefit of the human beings, several research projects were carried out. In this framework, the following study is presented, concerning the safety systems by keeping- back nets.

• Numerical and Experimental Investigation of SPH, SPG and FEM for High Velocity Impact Applications

  M. Becker, M. Seidl (ISL), M. Mehl (University of Stuttgart), M. Souli (University of Lille)

  During a high-velocity impact event large pressure, strain rate, and deformation occur. This is a very demanding scenario for mesh-based approaches like the FEM (Finite Element Method). In particular, for the description of fracture, special techniques like erosion or node splitting are required. For a comprehensive validation, we have designed a projectile surrogate and conducted impact experiments at different oblique angles in our laboratories. These experiments are observed with X-ray cinematography and physical properties for validation are extracted from the images. For the highly dynamic behavior during the impact, an alternative to mesh-based approaches are particle-based methods. LS-DYNA® offers two pure particle methods, SPH (Smooth Particle Hydrodynamics) and SPG (Smooth Particle Galerkin). This study compares SPH to the FEM results and the experimental data. Since the discretization requirements for the numerical approaches are different, it is not possible to compare exactly the same discretization. Instead, the number of nodes is chosen similarly. The accuracy is investigated qualitatively, using X-ray images, as well as quantitatively, using the extracted properties from the experiments.

• Numerical and Experimental Investigation of Asymmetrical Contact Between a Steel Plate and Armor-Piercing Projectiles

  T. Fras (French-German Research Institute of Saint-Louis); P. Pawlowski (Polish Academy of Sciences)

  The study presents the discussion on modeling of interactions between armor-piercing (AP) projectiles and add-on perforated plates realized by the experimental investigation, numerical finite-elements simulation and the simplified modeling based on the integration of the equations of motion of a rigid projectile. It is known that relatively thin steel plates with an array of holes, i.e. perforated plate, are efficient against impacts of small-caliber projectiles, which makes them applicable for light-weight armored vehicles as passive add-on armors. A number of holes in such plates increases the probability of asymmetrical contact between the plate and a small-caliber projectile, which causes its destabilization or fragmentation. Depending on the hit-point, AP projectiles behave differently; they may be strongly rotated if hit inside a hole, while hitting an area between holes, the damaged projectile core deviates from the initial trajectory. Impact on a hole-edge is the most efficient case of reducing the projectile’s perforation capacity, as its core may be broken or shattered. Due to the extensive, experimental ballistic testing performed on the bainitic, slotted plates impacted by 7.62 x 51 .308 Winchester AP projectiles, the failure modes of bullets were analyzed and constituted a basis for the numerical model validation. The reference numerical, Lagrangian model was implemented in LS-DYNA by 8-node constant-stress solid elements with one integration point and stiffness-based hourglass control. The modeling of impacts confirmed dependence between the projectile failure and the hit point. The localized-interaction model based on the integration of the equations of motion of a 6 DOF rigid projectile may be considered as a simplified method in the design of perforated pre-armors, in which obtaining the largest projectile distraction is the optimization aim. In such a robust model, the projectile-plate interactions are simplified and based on the integration of stress components, which are normal and tangent to the projectile’s contact surface. The target plate and projectile are discretized by a spatial grid of points, at which interaction forces are calculated. The performed numerical and experimental modeling proves a high protective efficiency of perforated steel plates against small-caliber AP projectiles. The asymmetrical contact between them results in a significant reduction of the bullet energy. The discussed methodology leads to improvements in the light-weight armors design.

• Numerical Determination of Permeability Tensor Components for 3D-braided Composites Using RVC Approach

  Fedor K. Antonov (Research Institute of Mechanics of Lomonosov Moscow State University)

  Today, one of the most promising trends in the design and manufacturing of composite structures is the use of 3D-reinforced thermoplastic composites. The present paper is concerned with the problem of resin transfer molding (RTM) process modeling, which is an important stage of 3D thermoplastic composites design. It is known that during the impregnation of woven preform local starved spots may occur, the textile pattern may distort and as a result the final structure will differ in mechanical properties form the initial design. The proper selection of RTM process parameters, such as injection holes placement, pressure profile and flow rate is a challenge for designers and process engineers. Nowadays, specialized software is developed for the solution of that problem, but the RTM process modeling in these environments is associated with considerable difficulties, caused by the need to set the permeability tensor, which components should be determined experimentally for each fiber material and for each weaving type. However, the permeability parameters can be determined in virtual experiments using the representative volume cell (RVC) approach by simulating a coupled-field problem of a viscous incompressible fluid flow through a porous medium. The paper demonstrates such an approach for permeability tensor components determination for the chosen 3D textile pattern using LS-DYNA with ALE computational method. Resin flow interaction with the fibers is modeled using FSI approach, while the flow through the fiber material is described by Darcy's law. As a result, resin pressure drop curves along three RVC directions were determined, on the basis of which the permeability tensor components were obtained.

• Numerical Differences Observed Due to Different Binaries of LS-DYNA and Due to the Use of Various Compiler Options

  Guangye Li, Wei David Chen, Jeff Zais - IBM

  This paper compares the numerical results generated with different versions of LS-DYNA, including SMP versions ls950d, ls950e, ls960 (all with single precision), SMP version ls960 with double precision, and the MPI version mpp960. The car crash simulation model used in this study is the Neon model generated by the National Crash Analysis Center. The plotted results include internal energies, sliding interface energies, displacements, velocities and accelerations. Most of the results were obtained on IBM AIX systems with POWER3-II and POWER4 processors. To show the effect of different floating point round off methods, results are compared between binaries generated from the exact same LS-DYNA source code, but compiled by using different compiler floating point options. Furthermore, the comparisons also included the numerical results from a Linux cluster based on the Intel Pentium III processor, using the LS- DYNA MPI version mpp960 binary compiled by using the Intel compiler.

• Numerical Dynamic Characterization of a Xenon Satellite Propellant Tank Employing Discrete Element Spheres

  Thomas PIERROT, Antoine GUILPIN, Tess LEGAUD, Vincent LAPOUJADE, Jean-Emmanuel CHAMBE, Miguel CHARLOTTE, Yves GOURINAT

  The ecological emergency makes the use of cryogenic or supercritical fluids more and more relevant. However, experimental tests and associated modelling of those liquids dynamic vibratory behaviour remain extremely challenging. Indeed, security, control and conditioning are critical issues due to the intrinsic fluid instabilities. Among those fluids, liquid hydrogen and supercritical xenon are both highly used in the spatial propulsion domain. Because of their hazardous behaviour, only few experimental dynamic tests have been performed to improve the knowledge of their behaviour inside a vibrating tank.

• Numerical Evaluation of an Add-On Vehicle Protection System

  Geneviève Toussaint, Amal Bouamoul, Robert Durocher, Benoît St-Jean (Defence Research and Development Canada), Jacob Bélanger (Numerica Technologies Inc)

  Defence Research and Development Canada (DRDC) has been involved in programs to reduce the vulnerability of vehicles to mines and improvised explosive devices for many years. In this work, DRDC was mandated to design and optimize an add-on vehicle protection system. Testing an entire vehicle against improvised explosive devices or blast landmines is both time-consuming and “expensive; therefore, to reduce costs, numerical simulations using the LS-DYNA hydrocode [1] were performed to support the development phase of the protection system. A finite element model of a simplified full-scale model of the vehicle called a mock-up was developed for this purpose. This model included the critical sections that were likely to be affected by a threat. Finite element studies were then performed to compare the performance of several protection designs and to orient on the choice of the final one. This paper presents the loading model that was used to simulate the effect of a landmine on the structure, the finite element (FE) models of the baseline and of three concepts and finally, a comparison of the relative performance of the different protection system designs.

• Numerical Evaluation of Low-Speed Impact Behaviour of a Fabric Layered Composite Plate in an Industrial Context

  S. Treutenaere, F. Lauro, B. Bennani, G. Haugou, W. Xu (University of Valenciennes); E. Mottola, T. Matsumoto (Toyota)

  The use of Layered Fabric Reinforced Polymers (LFabRP) in the automotive industry is growing significantly. In order to ensure the safety and design imperatives, a new material model was developed for the LFabRP to improve the predictability of low-speed impact simulations by means of Finite Element Analysis (FEA). The delamination prediction with FEA requires costly computation time methods such as the use of cohesive elements at ply interfaces. The proposed method includes the delamination evaluation directly within the material model and operates as a plugin for the constitutive intralaminar model. It allows to describe in an accurate manner the behaviour of a layered material by using only one shell element through-the-thickness. The material model recomputes a realistic strain field by means of a high-order zigzag theory. It takes into account the delamination effects on the continuity of the strain field but remains based on five degrees of freedom. By ensuring the internal energy equivalence between both element and material model theories, a realistic strain field for layered material is provided to the intralaminar material model. The intralaminar material model is based on a pre-existing continuum damage model (Onera Damage Model). To improve the efficiency and the precision for the modelling of LFabRP, friction mechanisms, a rheological viscoelastic model and a smeared crack approach for the fibre failure were introduced. The validation of the present model was carried out by means of controlled impact tests on a hydraulic high-speed jack. The LFabRP taken as reference is made up with three different fabric preforms. The material parameters are exclusively determined thanks to standard tests on the preforms taken individually on order to evaluate the model ability to predict low-speed impact behaviour. Moreover, experimental 3D damage reconstruction by means of ultrasonic inspection is compared to simulation predictions.

• Numerical investigation of draw bending and deep drawing taking into account cross hardening

  Clemens Barthel, Till Clausmeyer, Bob, Svendsen - University of Technology,Dortmund, Germany

  Sheet metal forming is one of the most important manufacturing processes. Computer simulation has become the tool for modeling such processes and also for predicting the springback in the final part. The talk will deal with two different metal forming processes, namely draw bending and deep drawing of a cup. In the draw bending case a metal strip is clamped into a testing device in such a way that it is bent over a roller. The strip is then moved along so that it undergoes bending and back bending while passing the roller. Subsequently the strip is released resulting in springback. Due to the geometry of a strip springback is significant in this process. Since during the draw bending process the state of stress is not the same in the middle of the strip and at the outer edge, high residual stresses remain in the workpiece. Though taken into account in the finite element model, contact is here of minor importance. Contact and also cross-hardening plays a more significant role in the second process. During the deep drawing a compression takes place in circumferential direction and in radial direction the ma- terial undergoes bending and unbending. Therefore orthogonal loading path changes occur. Some metals exhibit an increase of the yield stress after orthogonal strain path changes, i.e. so-called cross hardening. This is also the case for the air hardening steel LH 800 which is the material for both processes. To take the cross hardening into account one needs a material which goes beyond stan- dard isotropic and kinematic hardening. Such a model has been implemented via the user-material interface of LS-Dyna and ABAQUS. A comparison with standard hardening models as well as a com- parison of the results for the two different FE-codes will be given in the talk. Both processes were investigated also experimentally which facilitates a comparison of simulation results and test results. The parameter identification was done with LS-Opt and is subject of the contribution "Identification of an advanced hardening model for single phase steels" given by Muhammad Noman which will be presented at this conference as well.

• Numerical investigation of draw bending and deep drawing taking into account cross hardening

  Clemens Barthel, Till Clausmeyer, Bob, Svendsen - University of Technology,Dortmund, Germany

  Sheet metal forming is one of the most important manufacturing processes. Computer simulation has become the tool for modeling such processes and also for predicting the springback in the final part. The talk will deal with two different metal forming processes, namely draw bending and deep drawing of a cup. In the draw bending case a metal strip is clamped into a testing device in such a way that it is bent over a roller. The strip is then moved along so that it undergoes bending and back bending while passing the roller. Subsequently the strip is released resulting in springback. Due to the geometry of a strip springback is significant in this process. Since during the draw bending process the state of stress is not the same in the middle of the strip and at the outer edge, high residual stresses remain in the workpiece. Though taken into account in the finite element model, contact is here of minor importance. Contact and also cross-hardening plays a more significant role in the second process. During the deep drawing a compression takes place in circumferential direction and in radial direction the ma- terial undergoes bending and unbending. Therefore orthogonal loading path changes occur. Some metals exhibit an increase of the yield stress after orthogonal strain path changes, i.e. so-called cross hardening. This is also the case for the air hardening steel LH 800 which is the material for both processes. To take the cross hardening into account one needs a material which goes beyond stan- dard isotropic and kinematic hardening. Such a model has been implemented via the user-material interface of LS-Dyna and ABAQUS. A comparison with standard hardening models as well as a com- parison of the results for the two different FE-codes will be given in the talk. Both processes were investigated also experimentally which facilitates a comparison of simulation results and test results. The parameter identification was done with LS-Opt and is subject of the contribution "Identification of an advanced hardening model for single phase steels" given by Muhammad Noman which will be presented at this conference as well.

• Numerical Investigation of Carbon Braided Composites at the Mesoscale: Using Computer Tomography as a Validation Tool

  M. Vinot, M. Holzapfel, R. Jemmali (German Aerospace Center)

  So far analytical and, to a lesser extent, numerical approaches have been limited in their ability to predict the properties of braided composites because of the high complexity of the rovings’ interlacing. While many analytical theories have been developed to approach the stiffness of braided composites, only few models are able to reproduce their behaviour up to the global failure. As part of the research campus ARENA2036, which groups together partners from the industry and from research facilities, the DigitPro (Digital Prototype) project aims to develop a closed process chain for the manufacturing of braided composite parts, including, amongst others, braiding, draping and infiltration simulations as well as virtual material testings. The numerical material characterisation relies on the generation of an idealised geometrical model, using the open-source software TexGen, as a basis for finite-element simulations.

• Numerical investigation of the flow through fold-cores with LSDyna ICFD Solver

  F. Muhs, R. Walter (University of Stuttgart)

  In this work, the flow behavior of sandwich foldcores and their influence on the fluidic parameters such as pressure drop are investigated. The subjects of the investigation are three different foldcore geometries, which are analyzed with the ICFD solver from LSDyna. The results are then examined with results from numerical simulations using OpenFoam as well as experiments in the water channel.

• Numerical Investigation of Parameters Affecting Crush Mode of Triggered FRP Tube

  R. Akita (Itochu Techno-Solutions Corporation), A. Koike (Isuzu Advanced Engineering Center), A. Yokoyama (Kyoto Institute of Technology)

  When a quasi-static axial compressive load is applied to a Fiber Reinforced Plastics (FRP) tube, a continuous and stable fracture phenomenon called “Progressive Crushing” which shows highly effective energy absorption appears. The authors have constructed a cohesive element FEM model that can reproduce the process to this phenomenon. The purpose of this paper is to investigate the most stable chamfer shape for progressive crushing of the FRP tube, by using Cohesive Zone modeling technique. In the study, cross-sectional shapes of triangle type, chevron type and M-type were selected for the simulation of axial crushing test to confirm crush mode. Five geometric shapes of flat plate FEM model were considered to conducting a fundamental investigation. Furthermore, the 3D finite-element models of FRP tube using reasonably cross-sectional shapes were intended to obtain a well-balanced chamfer shape, therefore, providing useful suggestions for FRP tube design and/or manufacture.

• Numerical Investigation of Phase Change and Cavitation Effects in Nuclear Power Plant Pipes

  M. Souli, R. Messahel (University of Lille), B. Cohen (EDF UTO), N. Aquelet (LSTC)

  In the nuclear and petroleum industry, supply pipes are often exposed to high pressure loading which can cause to the structure high strains, plasticity and even in the worst scenario failure. Fast hydraulic transient phenomena such as Water Hammers (WHs) are of this type. It generates a pressure wave that propagates in the pipe causing high stress. Such phenomena are of the order of few msecs and numerical simulation can offer a better understanding and an accurate evaluation of the dynamic complex phenomenon including fluid-structure interaction, multi-phase flow, cavitation effects … For the last decades, the modeling of phase change taking into account the cavitation effects has been at the centre of many industrial applications (chemical engineering, mechanical engineering, … ) and has a direct impact on the industry as it might cause damages to the installation (pumps, propellers, control valves, …). In this paper, numerical simulation using FSI algorithm and the two One-Fluid Cavitation models “Cut-Off” and “HEM” of WHs including cavitation effects is presented.

• Numerical Investigation of a Glider Seat Cushion Under Shock Loading Using LS-DYNA®

  Devon Downes, Manouchehr Nejad Ensan, Eric Chen, Andrew Price, SilinYang, National Research Council Canada

  The objective of this study was to numerically simulate the shock mitigation capability of a glider seat cushion structure, at attenuating impact loading on the human pelvis. The cushion structure was comprised of two dissimilar 1” foam layers, T-41 and HS-70 foam, each colloquially known as Temper foam and Ethafoam, respectively. The Low Density Foam (Mat_57) constitutive material model was used to model the behavior of each cushion layer. The material model used the stress-strain curve to predict the response of the foam; this allowed for the rate sensitivity of foams to be modelled via different stress-strain curves. Pre-stressing of the cushion was achieved through gravitational loading until the cushion reached a steady state at which time the nodal stresses and strains were exported to the shock analysis. The simulated cushion was subjected to a 6.3g shock loading using the Frequency_Domain_Domain Response Spectrum keycard and random input profile using the Frequency_Domain_Random_Vibration keycard. In both cases the acceleration experienced by a human pelvis seated on the cushion was obtained and compared with available experimental data. The results showed the maximum acceleration experienced by the pelvis was in good agreement with experimental data. The model was then extended to determine the effectiveness of increasing the cushion thickness at attenuating shock loading on the pelvis. Comparing results with those found in literature, the numerical results were consistent in showing that increasing the cushion thickness is highly effective within a couple of inches after which increasing the thickness no longer provides any mitigating effects.

• Numerical Investigation of Landslide Mobility and Debris-Resistant Flexible Barrier with LS-DYNA®

  Yuli Huang, Jack Yiu, Jack Pappin, and Richard Sturt (Arup) Julian S. H. Kwan and Ken K. S. Ho (Hong Kong SAR Government)

• Numerical Investigation of the Nozzle Number on the Performance of Conical Vortex Tube

  M. Guen, O. Imine, A. Miloud (University of Science and Technology of Oran Algeria)

  A three dimensional computational fluid dynamic is used to analyze the mechanisms of flow inside a vortex tube. The K- ω SST turbulence model was applied to predict the performance and turbulent flow behavior inside the tube. The performance is related to the nozzle number. Five different nozzles as two, three, four, five and six were tested.

• Numerical Investigation of the Forming Behavior of Polymer Composite-Metal Hybrids using Fiber Reinforced Thermoplastic Tapes with Discontinuous Layup

  P. Kabala (TU Braunschweig), I. Karb (Compositence), D. Trudel-Boucher (National Research Council Canada), T. Ossowski, K. Dröder, A. Hürkamp (TU Braunschweig)

  The automotive industry is facing stronger requirements for crash safety and environmental friendliness of passenger cars from legislators, society and customers. This is reflected in legal requirements that regulate CO2 fleet emissions over the next few years as well as the relevance of CO2 emissions and vehicle safety as purchase criteria for vehicles [1, 2]. Fiber-reinforced plastics (FRP) offer a great potential to meet these requirements due to their high specific strength and stiffness as well as energy absorption capacity [3]. In particular, fiber-reinforced thermoplastics (FRTP) are suitable for large-scale production owing to their good recyclability and short cycle times [4].

• Numerical Investigations of Adhesive CFRP-Joints and Determination of Transverse Properties of the Adherends

  T. Behling, M. Holzapfel (DLR)

  Within the DLR (German Aerospace Center) project “Next Generation Car” adhesive joints of carbon fiber reinforced polymers (CFRP) are investigated. The focus was set on a numerical model to predict the failure mode (surface ply failure, delamination or adhesive failure) depending on the stacking sequence of the laminate. In a first step, the ‘five-point bending’ test was evaluated and chosen to measure the out-of-plane shear strength of a woven fabric and unidirectional CFRPs with various fiber angles. The results from the Digital Image Correlation (DIC) were compared to analytical and numerical models. An evaluation routine was derived to assess the out-of-plane shear properties of the CFRP. Finally, fine discretized numerical models of single-lap joint (SLJ) specimens were discussed and compared to tests.

• Numerical Investigations on Ricochet of a Spin-Stabilised Projectile on Armour Steel Plates

  M. Seidl, T. Wolf, R. Nuesing (ISL)

  Expanding urbanisation poses new challenges. Developing countries are facing a rapid Urbanisation with an estimated 4.3 billion urban inhabitants by 2035 [1]. History has shown that conflict and large-scale disasters are likely to occur where large populations reside [2]. During peace-keeping missions, soldiers move in closed urban locations surrounded by house walls and close to their armoured vehicles. In event of combat, the likelihood of projectiles ricocheting in a closed environment—than on the open battlefield—arises. This study examines projectile ricochet, which is the deflection off a surface of a projectile from its original trajectory after striking the target at a low angle [3], with focus on the influence of the angle of attack αt on the projectile behaviour after ricocheting. Numerical simulations—using the explicit Lagrangian solver—are used for a qualitative investigation, as measurement precision limits the determination of the influence of αt.

• Numerical Investigations to Determine Sources for the Scatter of the BioRID Dummy

  S. Stahlschmidt - DYNAmore GmbH, A. Hirth - Daimler AG

  The BioRID v2.5 model is in a very fine validation state until now. In some new tests for further validation of the model, one can observe a very strong scatter in some major signals of the tests. Some of these signals are used to calculate injury criteria which are used to determine the quality of a seat in rear crash scenarios in consumer tests. This paper describes the new validation test setup and gives an overview about the latest validation state of the BioRID model. Furthermore, the problem of scatter in the tests is shown and possibilities where this scatter may come from have been studied. The main focus is on the parameters of the BioRID model which have an influence on the neck load cell signals.

• Numerical Investigations to Determine Sources for the Scatter of the BioRID Dummy

  S. Stahlschmidt - DYNAmore GmbH, A. Hirth - Daimler AG

  The BioRID v2.5 model is in a very fine validation state until now. In some new tests for further validation of the model, one can observe a very strong scatter in some major signals of the tests. Some of these signals are used to calculate injury criteria which are used to determine the quality of a seat in rear crash scenarios in consumer tests. This paper describes the new validation test setup and gives an overview about the latest validation state of the BioRID model. Furthermore, the problem of scatter in the tests is shown and possibilities where this scatter may come from have been studied. The main focus is on the parameters of the BioRID model which have an influence on the neck load cell signals.

• Numerical Methodology for Thermal-mechanical Analysis of Fire Doors

  A. Bozzolo, C. Ferrando (D’Appolonia - RINA Group), A. Tonelli, E. Cabella (RINA Group)

  The certification process of a fire door implies that the structure is subjected to a standard fire test, to evaluate its resistance to thermal load. In particular, the door must fulfil specific requirements, such as, that the gaps among the door labyrinths and frame are able to stop flame propagation and that the mean and maximum temperature on the unexposed surface does not exceed defined values. The present paper describes the numerical methodology used to assess the fire performance of large fire doors (single leaf and double-leaf sliding doors), having a length of the order of 15-25m, commonly used for civil/industrial applications. These fire doors cannot be tested at lab scale, due to their size, and the only way to verify their structural integrity when subjected to fire is via numerical simulations

• Numerical Methods for the Analysis of Behind Armor Ballistic Trauma

  P. Zochowski (Military Institute of Armament Technology)

  The asymmetric character of current military conflicts causes that soldiers are often exposed to projectile impacts. Body armor (helmets, vests, etc.) protects them from the negative effects of highly dynamic loads by absorbing and dissipating kinetic energy of a projectile. However, severe local and distant injuries can occur in the human body, even in case of a non-perforating impact. A large amount of energy and momentum is converted into deep back face deformation (BFD) of the armor and dynamic acceleration of the body walls. In case of high-velocity impacts a trauma may be caused also by the stress waves generated and propagated through the tissues. Injury of the human body as a result of non-perforating projectile impact into the armor is defined as Behind Armor Blunt Trauma (BABT) [1].

• Numerical Model to Predict Kickback for Angle Grinders

  G. Fleury (INRS)

  Angle grinders are powertools used widely by companies and craftsmen for grinding and cutting applications. The operator must comply with the correct operating procedures and conditions, including the choice of an appropriate tool (cutting disc, grinding wheel, backing pad or brush), to ensure his safety. Even so, some working conditions can cause the rotating tool to be either pinched or snagged. As the rotational kinetic energy of the wheel decreases, a fraction of the energy is lost due to friction between the wheel and the workpiece, but if sliding occurs, some kinetic energy may be transmitted to the grinder leading to it being ejected from the point at which it binds with the workpiece. This sudden reaction of the powertool, known as “kickback”, can, in rare cases, cause serious or even fatal injuries to the worker. Through a working group, INRS, the French Research and Safety Institute for the Prevention of Occupational Accidents and Diseases, is investigating kickback events to identify the working conditions that are most likely to cause it. Preliminary research led to the development of a prototype test bench dedicated to reproducing kickback events in the laboratory. The test consists in pinching the rotating wheel of a grinder and observing the resulting ejection of the powertool. In order to improve our test bench and to increase our understanding of the mechanical phenomena leading to grinder ejection, a numerical model using the functionalities of LS-DYNA was developed. The model input parameters describe the features of the rotating wheel (mass, diameter, moment of inertia and initial angular velocity) and the features of the angle grinder (mass, moment of inertia, and position of the centre of gravity). The magnitude of the pinching force applied to the rotating wheel, the initial position of its application point and the coefficient of friction between the wheel and the pinching device are also taken into account by the numerical simulation. The kinetic energy of the grinder at the time of ejection and the direction of ejection are calculated in order to assess a kickback event. The task of this paper is to present the model and the results of the parametric study performed to assess the effect of each parameter on the magnitude and the direction of kickback.

• Numerical Modeling of Aluminum Forgings; Issues of Material Failure and Element Formulation

  F. Hekmat (GM), P. Du Bois (Consultant)

  The increased use of castings, forgings and thick extrusions in vehicle structures has led to the need for modeling certain parts with solid elements in crash simulations. Since the geometries of the considered parts are typically highly complex, using tetrahedral elements seems to be the practical solution. In the LS-DYNA simulation software, a multitude of different tetra element formulations are available however there is some uncertainty whether these elements can be used with confidence in a simulation for accurate fracture prediction based on a stress state dependent failure model.

• Numerical Modeling of Ballistic Penetration of Long Rods into Ceramic/Metal Armors

  Khodadad Vahedi, Najmeh Khazraiyan - Louisiana Tech University

  Penetration into ceramic/armor targets are of prime importance in research as well as industry and military applications. The recent advances in this field shows considerable improvements in the design of armor and civilian technology. Due to complexity of the problem and interdisciplinary of the subject, most of the works in this respect are experimental in nature. The cost of experimentation is high and the results obtained cannot be extrapolated to a large number of cases. However due to the advances of computer simulation, the field of numerical analysis is becoming highly attractive for application and research. Numerical modeling of ballistic impact of long rod penetrators into ceramic armor with semi-infinite backing targets is considered in this paper. An explicit, three-dimensional finite element code LS-DYNA is used in the analysis of the problem. The behavior of ceramic and backing materials are modeled as Elastic-Plastic Hydrodynamic with pressure cutoff and failure strain. The projectile is modeled as Johnson-Cook. Mie-Gruneisen and linear polynomial equation of state are used for materials. The impact velocity range is from 750 to 1350 m/s. The results of investigation are in a very good agreement with experimental data. Keywords: Ballistic impact; Ceramic armor; Finite element model; Long rod; Penetration depth

• Numerical Modeling of Concrete Response to High Strain Rate Loadings

  R. Sharath, D. Arumugam, B. Dhanasekaran, T. Subash (Larsen & Toubro)

  The dynamic characterization of concrete is fundamental to understand the material behavior in case of earthquakes and extreme dynamic events like Blast and impact. Extensive research is available on the study of quasi-static or nearly static behavior of concrete, but limited investigations/research exists on the prediction of dynamic response, especially under high strain loadings. Numerous material models are available for modeling the dynamic behavior of concrete, this research focusses mainly on numerical simulations of the quasi static and dynamic behavior of the concrete including the strain rate effects. For this research, popular material models MAT072R3 (KCC), MAT084 (Winfrith), MAT 272 (RHT) and MAT159 (CSCM) were implemented, that are available in the explicit dynamic software LS-DYNA. Single element tests verification subjected to varying strain rates in tension as well as in compression were the starting point of validation/comparison of different material models. The single element tests on different strain rates confirms the experimental behavior. Followed by, to study the quasi static behavior of concrete, numerical simulations of cylinder test (tension/compression) and three-point loading tests were carried out. Quasi static response of the concrete for the different material models were analyzed and the best suitable material model for the scenario is suggested. Backed up with the above numerical analysis results, reinforced and unreinforced concrete slabs subjected to blast loadings which usually involves high strain rates were analyzed. The damage behavior, crater formation and dynamic response of the slabs were compared with data extracted from the reference papers and relevant codes. Finally, the analysis results using different material models were summarized and discussed.

• Numerical Modeling of Friction Effects on the Ballistic Impact Response of Single-Ply Tri-Axial Braided Fabric

  Daihua Zheng, Wieslaw K. Binienda, Jingyun Cheng, Marcin Staniszewski - The University of Akron

  It has been shown by experiments that frictional effects play an important role in the energy absorption of fabrics subjected to ballistic impact. However, the specific role of friction is not well understood and established. In this paper, a detailed finite element model was developed, using LS-DYNA®, to parametrically study the frictional effects during the ballistic impact of a square patch of single-ply 2D tri-axially braided fabric. The individual yarns (bias and axial direction) in the fabric were modeled discretely and considered as a continuum by considering the measured properties of the braided fabric (weave architecture, crimp, yarn cross-section etc.). The friction between yarns at their crossovers and the friction between projectile and fabric were taken into account. The damage of a single yarn model were compared with the experimental data and included in the material model of the fabric. It was shown that the friction contributes to decreasing of the residual velocity of the projectile more quickly than the one without friction. Thus the fabric energy absorption capacity can be increased by 18%. The results from the simulation also indicated that the frictional sliding energy starts to play more important role when the fabric begins to get damage and more movements between axial yarns and braider yarns are involved.

• Numerical Modeling of Honeycomb Structure Subjected to Blast Loading

  M. Stanczak, T. Fras, L. Blanc (ISL), P. Pawlowski (Polish Academy of Sciences, Warsaw/ISL), A. Rusinek (Lorraine University)

  The main objective of this study is related to the modeling of an aluminum thin-walled honeycomb structure under blast loading. The blast test is performed by means of an explosively driven shock tube (EDST). A planar shock wave is generated by a small amount of an explosive charge detonated in front of the tube. The honeycomb core is compressed by a movement of the steel plate located at the end of the tube. In the experiment, the honeycomb deformation is recorded by a high-speed camera and the absorbed loading by the structure is measured by a force sensor fixed on the rear sample face. The simulation of the material behavior is carried out using the Lagrangian approach implemented in LS-DYNA, ver. R9.0.1. The shock pressure generated by the explosion is recalculated to define the force applied to the plate being in contact (*AUTOMATIC_SURFACE_TO_SURFACE with friction) with the honeycomb and causing its deformation. The honeycomb is meshed by shell elements with a default formulation ELFORM: BELYTSCHKO-TSAY. The front plate is assumed as a rigid body to induce a uniform deformation of the honeycomb structure modeled using *MAT_SIMPLIFIED_JOHNSON_COOK 098 with parameters published in, [1-2]. The simulations are performed for different number of unit cells to define the honeycomb, from a single cell to fifty-three cells, aiming to indicate a minimal cell number required to model properly the entire structure. A dependence of numerical results on the mesh size, unit cell dimensions, friction conditions and the strain rate has been verified. The comparison between values of the load absorbed by the sample crushed numerically and experimentally shows a good agreement providing an insight into mechanisms of blast wave absorption by honeycomb structures. Such an analysis may be further applicable in development of advanced cellular structures applied to dissipate blast energy.

• Numerical Modeling of Woven Carbon Composite Failure

  Paul F. Deslauriers, Duane S. Cronin - University of Waterloo, Alex Duquette - Multimatic Technical Centre

  This paper presents application of a MLT-based (Matzenmiller, Lubliner, Taylor) approach to model damage in woven carbon composite materials. The MLT formulation has been adapted to shell elements to model individual composite plies. The implementation of the model is discussed along with simple test cases to demonstrate the material response and limitations within the original MLT model. One of these limitations has been addressed through implementation of different damage parameters for tensile and compressive loading. In addition, this damage-based approach has been modified by the use of a non-local damage treatment to distribute accumulated damage across element boundaries. Application of this model to simple test cases indicates that the model demonstrates expected behaviour.

• Numerical Modelling and Biaxial Tests for the Mullins Effect in Rubber

  William W. Feng, John O. Hallquist - Livermore Software Technology

  The formulation, testing and numerical study of the Mullins effect on rubber are presented. Ogden first modelled the Mullins effect for studying the unloading in filled rubber. It has been extended here to include the Mullins effect on both unloading and subsequent loading. To demonstrate the Mullins effect experimentally, a new biaxial test, inflation of a plane circular membrane, is used. Some experimental test data are presented. An approximate solution, a relation between the inflation pressure and the displacement at the centre for the inflation of a plane circular membrane is presented. The test data and the approximate solution are used to determine the Mullins damage material constants. For more accurate study, the material constants can also be obtained through the combination of LS-DYNA, LS-OPT and the test data. The test data, analytical results and numerical results from LS-DYNA are shown. They agree with one another.

• Numerical modelling of impacts on ski safety nets

  Melissa Adoum - CRIL Technology Correspondence

  Safety nets are used to protect skiers during downhill competitions. However, although these nets are now able to retain skiers in almost all cases, the deceleration during such impacts can cause severe harm to skiers including hyperflexion injury or vertebra compaction. Experience showed that the behaviour of the nets is highly dependant on: • the material of which they are made of • the boundary conditions (installation and fastening). The aim of this study was : • to analyse the net constitutive material under dynamic loadings to determine its characteristics. • to analyse well defined impacts to be able to simulate them numerically • to improve the net behaviour during real impacts • to provide some recommendations concerning the geometry of the complete system. This study continues Fayçal Ben Yahia's work which was presented in Paris in June 2001. The whole study was performed under the funding of the French company Dalloz Montagnes and with the technical collaboration of the International Skiing Federation (FIS). As a first step, we used the tests on the net thread to model it in static and dynamic conditions. Then we compared the results from impact tests on small safety systems and simulations with LS-DYNA which led to the validation of the whole model. Finally, simulations of impacts on real size nets were used to study the influence of the boundary configuration on the net behaviour. The model developed during this study makes it possible to optimise the geometry of the whole system in order to increase skier protection.

• Numerical Modelling of Sheet Metal Damage in LS-DYNA using GISSMO

  Erik Stålbrand, Axel Hallén

  In this paper, a strategy for numerical simulation of cutting during concurrent pressing of stainless steel sheet metal is investigated while accounting for the stress triaxiality and Lode angle parameter. An inverse modelling approach is used, where both a material model and a damage model are calibrated. The damage model is developed using the GISSMO damage model (Generalized Incremental Stress State dependent damage Model).

• Numerical Modelling of Symmetric and Asymmetric Punching and Post-Punching Shear Responses of RC Flat Slab

  N. Ulaeto, J. Sagaseta (University of Surrey)

  The design and construction of civil engineering structures take into great consideration the sensitivity of such structures in the event of local failures. Flat slab structural systems are very prone to progressive collapse after the failure of a connection or column. Hence, to improve their robustness the introduction of integrity reinforcement is recommended in Eurocode 2, ACI 318-11 and Model Code 2010. However, very little investigation has been carried out on the asymmetric post-punching response of these connections or the actual contribution of designed integrity reinforcement to robustness at a system level. Presented in this paper, is a numeric approach developed for modelling the response of isolated RC flat slab test specimens using the finite element (FE) software LS-DYNA. This is in view of their incorporation into system models for both quasi-static and dynamic assessments of robustness in flat slab structures. Quarter FE models of four symmetric isolated RC flat slab specimens with experimental responses available in literature were developed. These quarter FE models were analysed numerically using a quasi-static displacement controlled approach and their flexural, punching shear and post-punching shear responses observed. A sensitivity analysis was carried out to obtain the optimum element characteristics for punching shear strength as well as other response criteria. Half asymmetric F.E models of two slab specimens were also developed and analysed. These provided the asymmetric punching and post-punching shear response of the slab specimens, assuming the loss of an interior column. Results of quarter symmetric FE models gave accurate predictions of slab load-deformation responses, punching and post-punching shear strengths. Maximum percentage differences of 2% and 3% were obtained when comparing test and FE results of symmetric slab specimens for peak punching and post-punching shear strengths respectively. Asymmetric FE models gave post-punching shear strengths lower than values obtained from tests on symmetric specimens. Robustness of flat slab structures after the loss of an internal column could be significantly overestimated where models adopted do not take into consideration such reductions in post punching shear strength. The results presented validate the use of this FE approach on LS-DYNA to predict the response of concrete flat slab connections.

• Numerical Modelling of the Fluid Structure Interaction using ALE and SPH: The Hydrodynamic Ram Phenomenon

  D. Varas, J.A. Artero-Guerrero, J. Pernas-Sánchez (University Carlos III of Madrid)

  Vulnerability against high-velocity impact loads is a critical issue for the design of aerospace structures due to the fact that aircrafts can be subjected to different types of loads during their service life which may cause a catastrophic failure. Bird strikes, hailstones, runway debris or even the ice released from the edge of a propeller blade may impact different parts of the fuselage. Wings represent the largest exposed area to impact threads of all the vulnerable components of an aircraft, therefore impacts onto a fuel tank inside the wings are considered of special relevance in aircraft vulnerability. Hydrodynamic Ram (HRAM) is a phenomenon that occurs when a high-energy object penetrates a fluid-filled container. The projectile transfers its momentum and kinetic energy through the fluid to the surrounding structure increasing the risk of excessive structural damage leading to a catastrophic failure. HRAM consists of four principal stages: shock, drag, cavitation and exit. Each stage contributes to structural damage in a different way and extent. The study of the HRAM phenomenon is not only important for the aircraft industry. High velocity impacts on fluid filled containers are of great interest for different industrial fields such as safety of industrial facilities or road haulage. In those cases, an impact in the vessel may produce the failure of the tank and serious consequences on the environment or even toxic and flammability effects. This work shows the numerical modelling developed to reproduce the effects of the HRAM phenomenon in different fluid filled square tubes (aluminum and CFRP) when impacted by steel spherical projectiles at different velocities and filling levels. The simulations are performed with the finite element code LS-Dyna using two different techniques for the fluid phase: the ALE and SPH formulations. Experimental tests providing the pressure in different points of the fluid, deformation of the walls and cavity evolution are compared with the numerical results in order to assess the validity and accuracy of both ALE and SPH techniques in reproducing such a complex phenomenon. In addition, the numerical results revealed that ALE is the most appropriate technique to simulate HRAM attending to its computational cost. The numerical model validated has contributed to a better understanding of the phenomenon as well as to study some possibilities to attenuate the effects of the HRAM on the affected structures. With the aim of reducing both the pressure wave generated by the impact and the cavity growing, thin sandwich structures with two metallic skins and a core of air have been located in different positions inside the fluid filled tube. The results show improvements regarding the vulnerability of the fluid filled impacted tubes.

• Numerical Modelling of the Plastic Deformation of Ti-6AI-4V Sheets Under Explosive Loading

  D. Kakogiannis, F. Coghe, L. Rabet (Royal Military Academy)

  The subject discussed in the present paper is the numerical modelling conducted during the design process of an experimental setup that is used to investigate the response of circular Ti6Al4V sheets under impulsive loading. A multiscale numerical modelling method to predict the plastic deformation of the material is presented focusing on the definition of the parameters of the Cazacu-Barlat model (*MAT_233/*MAT_CAZACU_BARLAT) as implemented in LS-DYNA. The definition of the parameters is linked to the microstructure of the material through the viscoplastic self-consistent polycrystal model(VPSC7) of Lebensohn and Tomé using the optimisation method of Simulated Annealing. A comparison is made between the direct input of the parameters and the parameter fit, provided by LS-DYNA. The method is validated with experiments where sheet specimens of two thicknesses are tested using an experimental setup with which a planar blast load is applied and with high speed cameras and the digital image correlation (DIC) technique, strains are measured in real time on the specimens.

• Numerical Prediction of the Dynamic Response of Prestressed Concrete Box Girder Bridges Under Blast Loads

  Ahmed Ibrahim, Hani Salim - University of Missouri

  Significant research has been performed on the response and retrofit of buildings under blast loads. Limited research exists on the response prediction and protection of bridges under near-field blast loads. This research focuses on the evaluation and assessment of box girder bridges under blast loads. The objective of this research is to develop a numerical model to predict the damage level in a concrete deck under blast loading and the corresponding dynamic response of the damaged bridge system. The damage level will be function of spalling/cratering the bridge will suffer under the near field detonations. The numerical analysis conducted using the explicit dynamic software LS-DYNA®, which has the abilities to model the blast load propagation towards bridge structures and to its response to these types of impulsive loads. The bridge has a simply supported span of 100 ft (30.48 m) and was designed according to the LRFD manual under HL-93 truck load. Different charge weights were located at a height of 30 inches (0.762 m) between the main vertical webs at the mid-span. The study shows that LS-DYNA predicted the damage severity under blast loads, especially since the testing under these loads might not be feasible. The studied Key parameters were the weight of the charge, and concrete deck properties. The results of this study make the finite element modeling an attractive alternative for blast testing when it is not feasible like the case of bridges. Comparisons of the numerical results are still necessary for code verification before this study can be expanded for additional parametric studies and design recommendations

• Numerical Prediction of the Dynamic Response of Prestressed and Reinforced concrete Hollow Core Slabs Under Blast Loading

  A. Maazoun, S.Matthys (Ghent University); J.Vantomme (Royal Miliatry Academy)

  This paper investigates the use and accuracy of finite element simulations by means of LS-DYNA of reinforced concrete hollow core slabs with a compression layer, simply supported and subjected to blast loading. The aim of this paper is to explain how to develop a numerical model, in order to predict the maximum deflection and crack distribution. Parametric studies related to hourglass energy, erosion value and the material model of the concrete are performed in order to evaluate the effects on the dynamic response of the hollow core slabs. This numerical analysis is completed by experimental tests for validation purposes.

• Numerical Ricochet Model of a 7.62 mm Projectile Penetrating an Armor Steel Plate

  Marvin Becker, Marina Seidl, Jean-François Legendre, French-German Research Institute of Saint-Louis;, Miriam Mehl, University of Stuttgart (Institute for Parallel and Distributed Systems);, M’hamed Souli, University of Lille (Mechanical Department)

  Armored vehicles are designed to favor projectile ricochet and thus avoid perforation while providing a certain surface obliquity for the most probable threat direction. In the latest development not only new materials but also new design approaches are investigated using computer simulations. These simulations allow us to study quantitative dependencies of certain parameters which are difficult to determine experimentally, e.g. the influence of the surface roundness on the ricochet behavior of the projectile.

• Numerical Simulation and Experimental Study for Magnetic Pulse Welding Process on AA6061-T6 and Cu101 Sheet

  Yuan Zhang, Geoff Taber, Anupam Vivek, Glenn Daehn, Pierre L’Eplattenier - Livermore Software Technology Corporation, Suresh Babu - The Ohio State University

  Magnetic Pulse Welding (MPW) is a collision welding process, similar to Explosive/impact Welding (EXW), but it utilizes electromagnetic force as the acceleration mechanism. Therefore, the available energy is much lower than EXW and it makes the process safer and more reproducible for sheet seam welding. However, the available energy must be better focused and controlled. In the sheet seam MPW process, a flyer sheet is driven and collides with a target sheet. True metallic bonding is achieved at the mating interface if contact takes place above a critical impact velocity at an appropriate impact angle. The impact velocity and angle are determined by the primary and induced electromagnetic fields. Both of them are strongly related to the geometry of the electromagnetic actuator and the discharge characteristics. An MPW launch system that will robustly provide bonding can either be developed empirically or through simulation. Here we attempt to provide the basis for a simulation-based approach to system design. The oblique MPW impact of AA606-T61 and Cu101 were analyzed using the newly available LS-DYNA®. Electromagnetism (EM) module in This module allows performing coupled mechanical/thermal/electromagnetic simulations. The simulation can predict the impact velocities and the temperature distribution along the mating interface. The simulation results were validated with measurement by Photon Doppler Velocimetry (PDV) measurement. Additionally, the simulation results also indicated rapid thermal cycling on the mating interface.

• Numerical Simulation and Experimental Study of Electromagnetic Forming

  Jianhui Shang, Larry Wilkerson, Steve Hatkevich - American Trim LLC, Pierre L’Eplattenier - Livermore Software Technology Corporation

  Compared to traditional sheet metal forming, electromagnetic forming (EMF) has several advantages, such as increased formability, cost savings and improved flexibility. There are many EMF applications in sheet meal forming, especially for aluminum alloys, because aluminum alloys have relatively low formability and high conductivity when compared to steel. The EMF process uses magnetic field generated by a conductive actuator upon large capacitor discharge to accelerate workpiece to high velocity. It is a complex coupled mechanical-thermal- electromagnetic phenomenon, which makes it difficult to numerically simulate. However, to save time and cost, numerical simulation is needed to accurately predict results of EMF. The Electromagnetism (EM) module of LS-DYNA® has been developed by LSTC, which can be used for numerical simulation of EMF. American Trim has applied this module to assist in its EMF designs. In this paper, to access the capability of EM module, the numerical and experimental results of sheet metal formed with EMF were compared. The experiment was to apply EMF for straight-edge flanging of Al 6061-T6 sheet. Then this flanging process was modeled using both SMP and MPP version of LS-DYNA EM module. The comparison between the final shapes of flanged samples and the numerical simulation showed the good correlation between experimental and numerical results, which indicates the good predictive ability of the LS-DYNA EM module for EMF.

• Numerical Simulation of a Flight Recorder’s Protective Case Penetration Resistance Test

  Alexander A. Ryabov, Vladimir I. Romanov, Sergey S. Kukanov, Dmitry V. Roschihmarov Sarov - Open Computing Center, Russia

  Development of a durable flight recorder’s protective case is a very difficult engineering problem. To save information, the case must be strong enough to withstand intensive accidental thermal and mechanical loading in aircraft crash. So the case must meets strong requirements. One of the toughest of these demands is that any flight recorder’s case must be strong enough to withstand a penetration resistance test - an impact of pin at any angle at a speed of 7.7 m/s. This paper presents the results of a series of 3D numerical simulations of penetration resistance test of a flight recorder’s protective case. The simulations performed with LS-DYNA. The computer simulations showed the most severe direction of pin impact to the case.

• Numerical simulation of a riveted helicopter panel during a ditching maneuver

  Guagliardo Davide, Cestino Enrico, Gaglione Pietro, Trofa Stanislao, Di Nuzzo Salvatore, Liquori Ferdinando

  The following study aims to present an impact analysis in water of a simplified geometry of a riveted helicopter panel. The analyses were conducted using Ls-Dyna solver, applying the FEM methodology to simulate the impacting body and the water, which was modelled using the SPH (Smoothed-Particle Hydrodynamics) method. The study focuses specifically on a geometry representing an aluminium box of dimensions compatible with those found in the underfloor areas of helicopters. In the first part of the paper, different types of rivet models will be investigated considering a single riveted lap joint under tension, highlighting the best choice especially when elastic-plastic behaviour should be considered. The focus will be, in the second part, on the forces that develop on the bottom plate and the rivets connecting the plate to the two reinforcement elements, namely the stringers and frames, during a ditching maneuver. A comparison will be conducted between the measured pressures and those projected by analytical theories. Additionally, the influence of air-cushioning will be investigated, discussing the benefits and the conditions under which it can be neglected.

• Numerical Simulation of Aircraft Seat Compliance Test using LS-DYNA® Implicit Solver

  Satish Pathy, LSTC, Livermore, CA;, Thomas Borrvall, DYNAmore Nordic AB, Linköping, Sweden

  With the possibility of using numerical simulation results in place of dynamic tests for aircraft seat compliance, use of LS-DYNA for this purpose is gaining traction and visibility. This test is done in two parts – In the first part which is quasi-static, the seat undergoes “roll” and “pitch” at the attachment mounts, which preloads the seat structure, and, in the second part an acceleration pulse of 16g’s is applied to the seat system and dummies. If the seat integrity is maintained, the test is considered a pass and the seat gets certified. The challenge is, the first part of the simulation is quasi-static and currently explicit solver is used, which means the solution has to be time-scaled. Since the seat components are discretized with fine mesh, mass-scaling is used to an extent the regulation allows. Time-scaling and mass-scaling is necessary to achieve a decent turn-around. This paper explores the possibility of using LS-DYNA’s Implicit solver to reduce the computation time for the quasi-static part of the simulation – by improving the solver and developing FE dummies that are implicit-ready.

• Numerical Simulation of Aluminum Alloy Forming Using Underwater Shock Wave

  Hirofumi Iyama - Yatsushiro National College of Technology, Kousei Takahashi - Kumamoto Industrial Research Institute, Takeshi Hinata, Shigeru Itoh - Kumamoto University

  In recent years, on automobile industry, the car has body using aluminum alloy. As for this material, #5000’s, 6000’s and 7000’s aluminum alloy is used well. However, the sheet metal forming of these materials by the static method, such as the hydro bulge forming and general punching, is very difficult, because these are little elongation compared with major steel. We considered application of the explosive forming. Therefore, we have tried free forming of aluminum alloy as the basic study. We compared the elongation of aluminum alloy by the explosive forming with punching. Consequently, it was larger for the amount of deformation of aluminum alloy by the explosive forming. In addition, we have done a theoretical elucidation. It is important the investigation of deformation process of aluminum plate by the explosive forming. Therefore, we solve using the numerical simulation by LS-DYNA. In this simulation, it carried out detonation process of the explosive, propagation process and deformation process of aluminum alloy.

• Numerical Simulation of Cell Venting within a Simplified 18650 Li-Ion Battery Pack

  D. Grimmeisen, M. Schneider (CASCATE)

  Violation of nominal operating conditions in Li-ion batteries can lead to internal damage and failure of the cells. This usually triggers chemical reactions that produce a large volume of hot gas. As a safety feature, 18650 battery cells are equipped with a safety vent. Once an internal pressure threshold is exceeded, the vent opens, and the gas escapes the cell at a high velocity to prevent uncontrolled structural failure. Within a battery pack, the hot gas needs to be guided to exit the pack while at the same time keeping neighbouring battery cells cool enough to stay within the safe temperature range. CFD simulation offers the capabilities to explore the mechanism of battery cell venting and flow guidance. This paper describes how such a simulation can be set up and run. Several steps are necessary to achieve this. First, Simcenter Battery Design Studio is used to model the 18650 battery cells. However, it is also described how this step can be avoided if certain prior knowledge about the process is available. Simcenter STAR-CCM+ is used for that and all subsequent steps. The cells are then assembled to a battery module and placed within a simplified battery pack housing.

• Numerical Simulation of Consequences of Passenger Aircraft Tyre Damage

  Dr. Alexander Ryabov , Dr. Vladimir Romanov , Sergey S. Kukanov , Dr. Andrey Kudryavtsev , Anatoliy Botvinkin - Sarov Engineering Center, Maxim Litvinov , Vladislav Gubin , Dmitry Egorov - CJSC Sukhoi Civil Aircrafts

  All new-designed passenger aircrafts have to meet strict national and international safety requirements in accidents. One of the accidents is pneumatic tyre failure (a tyre burst). Because of that the tyre can be fragmented. An air stream from the tyre and some tyre pieces under the air stream can impact on vitally important aircraft system elements in the landing gear box and disable or break them. In this case a designer has to provide a documentary evidence of system assembly reliability in possible accident cases considered. The problem solution by means of direct full-scale tests is too much expensive. Therefore the experimental-numerical method based on the optimal combination of a detailed computer simulation and model experiments for the computer simulation verification can be used. Numerical simulation and some experimental results of dynamic elastic-plastic deformation researches of some aircraft system subjected to the air flow pressure and the tyre piece impact are presented in the paper. The numerical investigations are performed by means of gas-dynamics and structural strength conjugate problem solution on the basis of STAR-CCM+ and LS-DYNA® software.

• NUMERICAL SIMULATION OF DAMAGE IN THERMOPLASTIC COMPOSITE MATERIALS

  Kevin Brown - University of Nottingham, Richard Brooks, Nicholas Warrior

  Thermoplastic composites are being considered for application in vehicle bumper and front-end structures for increased pedestrian protection. This paper describes recent progress in the calibration and validation of LS-DYNATM material model 162 (*MAT_COMPOSITE_DMG_MSC) for the modelling of impact damage in the glass/polypropylene commingled fabric thermoplastic composite, TwintexTM. In this study, MAT 162 is calibrated by using a series of tests that were conducted at quasi-static and dynamic loading rates. These consisted of in-plane tension, shear and compression tests. A novel procedure for calibrating in-plane shear damage is presented. To demonstrate the predictive capabilities of the model, the response of TwintexTM laminates subject to dynamic impact loading is simulated. The force–time histories and damage predictions are successfully compared with corresponding experimental instrumented falling weight test results. It is concluded that MAT 162 provides a versatile tool for predicting damage progression in thermoplastic composites.

• Numerical Simulation of Elastic-Plastic Deformation of Aircraft Fuel Tank Access Cover Impacted by Tyre Fragment

  Alexander A. Ryabov, Vladimir I. Romanov, Sergey S. Kukanov, Anatoliy K. Botvinkin (Sarov Engineering Center)

  All new-designed passenger aircrafts have to meet strict national and international safety requirements in accidents. One of the possible accidents is pneumatic tire damage, which can become the reason of the tire tread fragmenting. Some fragments of the tire tread with different mass and velocity can impact and break different plane elements. According to the safety requirements the designing company has to prove that the new plane withstands the tire fragment impact. The development tests to meet this requirement are obviously difficult and costly experiments, so it is very cost-effective to use a numerical simulation in the design of a plane to solve the problem. In this case the simulations results should be verified by the model experiments. The results of LS-DYNA£ numerical simulation of an aircraft fuel tank access cover elastic-plastic deformation are presented in the paper. The results are compared to experimental data, obtained for the covers subjected to tire fragment impacts at different angles with the speed of 110 m/s. Comparison of the cover residual deflection and strain time-histories shows that the simulation results are in a good agreement with the experimental data.

• Numerical Simulation of Electrohydraulic Forming using Coupling of ALE and Lagrangian Elements

  M. Woo, J. Kim (Pusan National University)

  Electrohydraulic forming is a high-speed forming process that employs high-pressure shock wave in fluid. When the electric energy is discharged from a capacitor bank, it is transferred to the water through the electrode bar and it makes the fluid into a high-pressure plasma state. Due to the high-pressure water, the sheet can be deformed into the die shape. Because the numerical model of electrohydraulic forming deals with fluid and structural models at the same time, it needs coupling mechanism for parts. Therefore, in this study, numerical model for electrohydraulic forming was developed using the coupling of ALE (Arbitrary Lagrange-Eulerian) and lagrangian mesh. The fluid parts, plasma, vacuum and water, were modelled with ALE elements and structural parts, die, chamber and sheet metal were modelled with general lagrangian mesh. The results of the numerical simulation showed that the plasma and water parts expanded due to the input energy, and the sheet metal was deformed with a speed above 100 m/s due to the pressure wave of the fluid parts.

• Numerical simulation of ground impact after airdrop

  Yves de Lassat de Pressigny - Centre d’Essais en Vol, MinDef/DGA/DE, France, Vincent Lapoujade - CRIL Technology, France

  The airborne forces of many countries use honeycomb paper as energy damping material (EDM) for heavy cargo airdrop. Its roughly constant crushing resistance makes the dimensioning of the kinetic energy absorber layer quite easy. Yet the velocity and attitude of a parachute at ground impact is variable, due to weather conditions, or undamped pendulum movement of the load under the parachutes. Those parameters have a big influence on the shock level generated at ground impact. Since ground and flight testing is long and expensive, the Flight Test Centre (CEV) of the French MoD has been developing simulations tools to evaluate the EDM design efficiency for all impact conditions at the rigging’s draft design level. In 2003, the CEV definitely chose LS-DYNA for that kind of simulation and proved the consistency of the results for Shock Response Spectrum (SRC) prediction and comparison. The paper presents the modelling work made for the EDM an application results for ammunition and vehicle airdrop.

• Numerical Simulation of High-Speed Joining

  M. Gerkens, Prof. G. Meschut (Universität Paderborn)

  The increasing trend of multi-material and space-frame design in automotive car body construction consolidates the need for mechanical joining technologies with one-sided accessibility. The high-speed joining (also called “RIVTAC®” or “Impact”) is an innovative and flexible technology. A tack with a profiled shank and an ogival shaped tip is pushed into the joining partners with a speed of 20 to 40 m/s without pre-punching. The plastic and friction work is converted into heat which causes an abrupt rise of temperature in the joining zone. This improves the flowability of the material which leads to filling the annular grooves on the shank of the tack. A high form fit is achieved. Simultaneously, a non-positive connection due to pressing and compression of the material is obtained, especially for high-strength steels. Furthermore, effects of inertia are used, so that thin-walled structures can be joined without any additional tools (e.g. a die). But the local stiffness is an important aspect. The axial force during the joining process and the radial strains effects a deformation of the joined structure. The numerical simulation is a powerful tool to predict the deformation and the joinability of a complex structure as well as the mechanical properties of the connection. The lecture is about detailed process- and loading-simulation of high-speed joining in LS-Dyna. Experimental and simulative investigations reveal the necessity of a correct material description. As figure 1 illustrates, the material flows equally towards the joining direction (look on the ridge). Figure 2 shows the heating up to several hundred degrees because of plastic work and friction, which improves the flowability in the joining zone.

• Numerical Simulation of Impact on Solid Rocket Motors

  N. Couroneau-Mortreuil (DGA EM)

  Weapons safety and vulnerability have become a major field of activities for DGA EM in the past decades. It is now a major actor, along with its state and industrial partners, for the safety evaluation and the qualification of all missiles to be fielded in the French armed forces. While test activities were presented in a previous paper [1], the present paper focuses on the simulation activities and the numerical tools developed to assess the vulnerability of solid rocket motors (SRMs) under impact loading. Finite element models for low or high velocity impact are both developed using LS-DYNA but the methods and constitutive models differ.

• Numerical Simulation of Impact Welding Processes with LS-DYNA

  C. Pabst, P. Groche (Technical University Darmstadt)

  Impact welding enables metallurgical bonding even between dissimilar metals. The bond is formed during a high speed impact between the two workpieces to be joined. In the application, the accelerating force is provided by an explosive (explosion welding, EXW) or by an electromagnetic field (electromagnetic pulse welding, EMPW). One workpiece is usually accelerated within a few millimeters up to 200m/s and above

• Numerical Simulation of Light Armoured Vehicle Occupant Vulnerability to Anti-Vehicle Mine Blast

  Kevin Williams - Defence R&D Canada - Valcartier, Francois Fillion-Gourdeau - Université Laval

  An ongoing program at Defence R&D Canada to reduce the vulnerability of Light Armoured Vehicle (LAVs) to anti-vehicular blast mines is relying heavily on numerical simulation to help design and optimize add-on armour systems. One of the greatest challenges faced during the evaluation of the vulnerability of a given vehicle to blast mines is not only assessing the structural response of the vehicle but also evaluating the injuries sustained by the vehicle occupants due to the accelerations induced by the blast. Anthropomorphic test devices (ATDs such as the Hybrid III) are used in the experimental program but these human surrogates were developed specifically for automotive crash tests. The loading conditions observed during a mine detonation, particularly where there is a breach in the hull of the vehicle, are such that extensive damage can be caused to the ATD. In addition, placing more than 2 or 3 ATDs in a vehicle is prohibitively expensive. As a result, the use of ATDs is somewhat limited. Numerical techniques allow any number of vehicle occupants to be simulated even in scenarios where there is potentially catastrophic failure of the hull. This paper presents the results of a series of simulations performed with LS-DYNA. A finite element model of the Canadian Cougar AVGP LAV, previously validated against experimental data for mine blast, was modified to include details of the rear crew compartment. The vehicle occupants were modelled using the GEBOD simplified ATD model incorporated in LS-DYNA. A simulated blast from a 6-kg C-4 mine surrogate was used to load the vehicle model. The predicated accelerations and velocities for various parts of the GEBOD dummies were compared to injury threshold criteria.

• Numerical simulation of low-velocity impact loading of polymeric materials

  H. Daiyan, F. Grytten, E. Andreassen, R.H. Gaarder, E.L. Hinrichsen - SINTEF Materials and Chemistry, O.V. Lyngstad - Plastal AS, H. Osnes - University of Oslo / Simula Research Laboratory

  Simulation of ductile polymers subjected to impact loading has become an important topic [1, 2], especially for automotive components related to passenger and pedestrian safety. The aim of our work is to establish and validate numerical models for impact response, and this presentation will focus on a study of impact on injection molded polypropylene plates. SAMP-1 (Semi-Analytical Model for Polymers) [3] was selected as constitutive model in LS-DYNA. This model takes tabulated data from experiments as input, and includes strain rate effects, pressure sensitive plasticity, plastic volume dilatation and damage. As the material behavior is complex, and data for large strains are needed, a major task is to obtain reliable data from material tests. Uniaxial tension and uniaxial compression tests were performed to calibrate the constitutive model. Three-dimensional digital image correlation (3D-DIC) [4] with two cameras and stereo vision was used to determine full-field displacements during uniaxial tensile tests, in order to quantify plastic volumetric strains and to obtain true stress-strain curves (the isochoric assumption is invalid for the present material). Uniaxial compression tests were made with short specimens in order to avoid buckling. Falling weight impact of plates (centrally loaded, circular clamping) and bars (three-point bending), and quasi-static three-point bending of bars, were simulated. Measured force vs. displacement, and permanent deformation of plates, were compared to numerical predictions. Figure 1 shows results for falling weight impact of a 4 mm thick plate. SAMP-1 is suitable for such materials, but improved material data are needed for e.g. strain rate effects and stress state effects.

• Numerical simulation of low-velocity impact loading of polymeric materials

  H. Daiyan, F. Grytten, E. Andreassen, R.H. Gaarder, E.L. Hinrichsen - SINTEF Materials and Chemistry, O.V. Lyngstad - Plastal AS, H. Osnes - University of Oslo / Simula Research Laboratory

  Simulation of ductile polymers subjected to impact loading has become an important topic [1, 2], especially for automotive components related to passenger and pedestrian safety. The aim of our work is to establish and validate numerical models for impact response, and this presentation will focus on a study of impact on injection molded polypropylene plates. SAMP-1 (Semi-Analytical Model for Polymers) [3] was selected as constitutive model in LS-DYNA. This model takes tabulated data from experiments as input, and includes strain rate effects, pressure sensitive plasticity, plastic volume dilatation and damage. As the material behavior is complex, and data for large strains are needed, a major task is to obtain reliable data from material tests. Uniaxial tension and uniaxial compression tests were performed to calibrate the constitutive model. Three-dimensional digital image correlation (3D-DIC) [4] with two cameras and stereo vision was used to determine full-field displacements during uniaxial tensile tests, in order to quantify plastic volumetric strains and to obtain true stress-strain curves (the isochoric assumption is invalid for the present material). Uniaxial compression tests were made with short specimens in order to avoid buckling. Falling weight impact of plates (centrally loaded, circular clamping) and bars (three-point bending), and quasi-static three-point bending of bars, were simulated. Measured force vs. displacement, and permanent deformation of plates, were compared to numerical predictions. Figure 1 shows results for falling weight impact of a 4 mm thick plate. SAMP-1 is suitable for such materials, but improved material data are needed for e.g. strain rate effects and stress state effects.

• Numerical Simulation of Rock-Cutting Mechanism of Tunnel Boring Machine

  R. Nasouri (University of Texas), H. Rokhy (Amir Kabir University), A. Matamoros, A. Montaya (University of Texas) R. Backzadeh (Urmia University)

  Accurate estimation of acting forces on the disk cutter is very important in the design of Tunnel Boring Machines (TBM) operations factors such as propulsion (driving) force and torque. To do this, first the forces applied to a single disk cutter, as well as its performance for a particular rock, are determined by performing a linear cutting machine (LCM) test. The results are then generalized for design of TBM on the same rock. In the present numerical study, the linear cutting machine test for a fixed cross-sectional cutter was simulated using LS-DYNA software, and the results of the numerical model were compared with the laboratory results. The results show that the use of the Lagrangian solution method is not appropriate due to the strong dependence of the accuracy of the results on the failure criterion defined to remove the elements, and the use of the SPG solution method will be a more appropriate option instead. Also, using the RHT material model instead of the JHC model will have a much better estimate of the width of the damaged area in the rock. The accuracy of the results shows that in the next step, this solution method can be used to simulate the rotational cutting machine (RCM) test.

• Numerical simulation of shock events and associated response of satellite

  Tess Legaud, Nicolas Van Dorsselaer, Vincent Lapoujade, Simon Lemay

  The paper presents CNES’ and Dynas+ partnership recent activities to improve shock events simulation and predict shock propagation in structures and equipment. The last activities presented here have been focused on shock test prediction by numerical analysis (i.e. virtual shock testing). The simulations were performed using LS-DYNA®, whereas the use of explicit non-linear computation codes is not common in the space industry to deal with spacecraft mechanical environments. Especially, the activities aimed at modelling physically the shock event generated by one of CNES’ pyrotechnic test device and to predict the acceleration levels generated by this source on the structural model of a microsatellite. To do so, multiple intermediate steps had to be studied, beginning by the modelling of a simple sphere impacting a plate. The model complexity increased progressively to reach the modelling of a satellite vibrations induced by shock sources. In order to assess model predictability, all the tests were performed at various shock energies and compared to experimental results. This paper will present the results and comparisons with experimental SRS (Shock Response Spectrum) obtained starting with “simple” cases up to cases integrating complex structures and shock sources.

• Numerical simulation of spiral-strand cables subjected to high velocity fragment impact

  R. Judge, Z. Yang, S.W. Jones - University of Liverpool, G. Beattie - Arup

  This paper presents the results of a numerical study carried out to evaluate the response of high-strength steel spiral-strand cables, when subjected to high velocity fragment impact. A detailed numerical model of a 60 mm diameter spiral-strand cable subjected to impact from a 20 mm fragment simulating projectile has been developed for analysis in LS-DYNA. Detailed consideration was given to the complex geometry of the cable, wire-to-wire contact and friction, cable-end boundary conditions and appropriate material modelling. Fragment velocities between 200 and 1400 m/s were modelled to assess the penetration and perforation resistance of the cable and to study the magnitude of localised cross-sectional cable damage. The numerical results were validated against initial laboratory tests. In both the tests and numerical simulations none of the cables were perforated by the fragments and good agreement was seen in the damage area, the fragment penetration depth and the wire splay phenomenon.

• NUMERICAL SIMULATION OF THE WOOD RESPONSE TO THE HIGH VELOCITY LOADING .

  J. Buchar - Mendel University of Agriculture and Forestry, Czech Republic, J. Voldrich - Research Center of the West Bohemia University, Czech Republic

  The experiments where the freely supported spruce beams have been loaded by the detonation of an explosive charge have been evaluated using of the numerical simulation. The explicit Lagrangean finite element code LS DYNA 3D has been used to analyse the beam response. The wood has been considered as global orthotropic linear elastic material with a material damage. The material damage has been described by the strain at the wood failure. This simple material model seems be better than the Tsai - Wu model widely used in another numerical simulations. Spruce wood , beam , material damage, explosive loading, finite element , numerical analysis Wood is an anisotropic cellular material such as honeycombs, metal ring systems, polymeric foams and some others . These materials are very convenient for the design of impact energy absorbers and as core materials in lightweight structures. Their behaviour under static loading is well summarised in the book (Gibson and Ashby 1988). Wood in particular has also been used as a protective material for high velocity impact events for many centuries (Johnson 1986a, 1986 b) and is very often used as an impact energy absorbing material at the design of the transportation flasks for nuclear fuel etc. There have been only a few systematic studies of the behaviour of wood under high rates of loading following from some impact events (Johnson 1986a). Recently the extensive impact test data have been obtained for some wood species (Reid and Peng 1997, Harrigan et al. 1998) . These data have been used for the development of the models of the macro – deformation and micro – deformation modes resulting from the dynamic uniaxial compression at the specimen impact. The present paper focuses on the other kind of the dynamic loading which is the effect of the detonating explosive. The study of this problem has some practical applications . Wood may be successfully used as a part of a structure which should absorbed most of the energy of the mine explosion etc. It is obvious that there is a variety of different arrangements, kind of wood, thickness of wood layer etc. In order to reduce the number of expensive experiments some reliable numerical simulation is necessary. The present paper deals with the problem of such numerical analysis using of the finite element code LS DYNA 3D.

• Numerical Simulation of the Laser Scoring Line Behavior in Airbag Deployment

  M. Nutini, M. Vitali (Basell Poliolefine Italia), S. Bianco, D. Brancadoro, A. Luera, D. Marino (FCA), M. Olivero (CRF)

  The airbag door system is one of the most delicate aspects in the design phase of a car instrument panel: seamless systems are increasingly used, which combine styling criteria with good functional performances. These systems typically include a tear seam, which may be obtained through laser scoring , to pre - determine the location of the opening during airbag deployment. The desig n of the scoring line is currently validated through experimental tests on real life exemplars, submitted to airbag deployment, resulting in high development times and relevant costs. This is the main reason which suggests proposing numerical simulation in the design phase, not to substitute actual part homologation by testing but in order to limit the scope and complexity of the experimental campaign, thus reducing the development costs and the time to market.

• Numerical Simulation of the Critical Blast Wave of Mines on APV's Crew Members

  Alon Brill - Netvision, Paul A. Du Bois - Consulting Engineer

  Blast wave generated by energy released when a mine is detonated, travels through the air at supersonic velocity. Has a high pressure front and hits a vehicle in about 100 μm giving rise to overpressure on it. Blast created by expanding explosion products and air moving behind shock front; results in dynamic pressure on a vehicle. Soil ejecta thrown up when mines are buried in the ground; augment significantly impact of blast wave. Survivability of military vehicles with respect to mine blast loading has two aspects. First structural survivability must be ensured meaning that the vehicle’s armour must not be penetrated and the passenger compartment must remain intact to prevent overpressure resulting from mine explosions acting directly on crew causing primary injury (lung damage, ear drum puncture) there must be no air paths though which it could propagate. The second aspect is occupant survival which is mainly a function of acceleration levels in the occupant pelvic, spine and head region due to the initial acceleration pulse. To attenuate transmission of stress waves crew seats should be attached to hull sides or roof and incorporate damping materials. To avoid being struck by bulging floor crew’s seats should be well above it and their feet should not rest on it but on inner floor spaced from hull bottom plate or on raised foot rests. Reduction can be achieved by designing the vehicle motion due to explosions. The Motion of vehicles due to mine explosions is related not only to their weight but also their size and shape because of the impulse which act on them. Impulse is a function of pressure, angle and time of the blast, the vehicle’s projected area and is minimized by the hull being “streamlined” with a V-bottom and no sponsons or wheel wells. Another way to keep acceleration levels low is to use energy absorbing seat systems which come however at substantial cost. In this study numerical simulation was used to determine the critical mine blast loads in terms of an equivalent charge of TNT for vehicles of different mass. Although many simplifying assumptions were made (such as a rigid vehicle capsule), the simulation allows a fast estimate of the need for energy absorbing seat systems for a given vehicle class under a variety of loading scenarios. The study’s conclusions were largely confirmed by a series of full scale experiments that were performed 6 months after the start of the simulation work.

• Numerical Simulation of the Critical Blast Wave of Mines on APV's Crew Members

  Alon Brill - Netvision, Paul A. Du Bois - Consulting Engineer

  Blast wave generated by energy released when a mine is detonated, travels through the air at supersonic velocity. Has a high pressure front and hits a vehicle in about 100 μm giving rise to overpressure on it. Blast created by expanding explosion products and air moving behind shock front; results in dynamic pressure on a vehicle. Soil ejecta thrown up when mines are buried in the ground; augment significantly impact of blast wave. Survivability of military vehicles with respect to mine blast loading has two aspects. First structural survivability must be ensured meaning that the vehicle’s armour must not be penetrated and the passenger compartment must remain intact to prevent overpressure resulting from mine explosions acting directly on crew causing primary injury (lung damage, ear drum puncture) there must be no air paths though which it could propagate. The second aspect is occupant survival which is mainly a function of acceleration levels in the occupant pelvic, spine and head region due to the initial acceleration pulse. To attenuate transmission of stress waves crew seats should be attached to hull sides or roof and incorporate damping materials. To avoid being struck by bulging floor crew’s seats should be well above it and their feet should not rest on it but on inner floor spaced from hull bottom plate or on raised foot rests. Reduction can be achieved by designing the vehicle motion due to explosions. The Motion of vehicles due to mine explosions is related not only to their weight but also their size and shape because of the impulse which act on them. Impulse is a function of pressure, angle and time of the blast, the vehicle’s projected area and is minimized by the hull being “streamlined” with a V-bottom and no sponsons or wheel wells. Another way to keep acceleration levels low is to use energy absorbing seat systems which come however at substantial cost. In this study numerical simulation was used to determine the critical mine blast loads in terms of an equivalent charge of TNT for vehicles of different mass. Although many simplifying assumptions were made (such as a rigid vehicle capsule), the simulation allows a fast estimate of the need for energy absorbing seat systems for a given vehicle class under a variety of loading scenarios. The study’s conclusions were largely confirmed by a series of full scale experiments that were performed 6 months after the start of the simulation work.

• Numerical Simulation of the Ice-Structure Interaction in LS-DYNA

  Hamid Daiyan and Bjørnar Sand - Northern Research Institute (NORUT Narvik)

  Design of offshore structures in Arctic waters is strongly dependent on local and global ice loads. These loadings are, in general, contact forces transmitted to the structures during interaction with ice floes, ice ridges or icebergs. The prediction of ice forces on structures relies heavily on a thorough understanding of mechanical behavior of sea ice as well as on in-depth knowledge of interaction between ice features and structures. Sloping, or conical shaped structures are commonly used structures for arctic oil and gas exploration and production due to the fact that these structural shapes induce ice bending failure on the structure slope, so that the horizontal ice loads on the structure can be reduced compared to a crushing type of failure, which occurs when ice floes interacting with vertical structures. As an ice sheet advances toward a conical or sloping structure, the ice load increases until the drifting ice sheet fails by bending and forms ice blocks. Following the failure of the ice cover, the failed ice blocks are pushed up the sloping structure or forms ice rubble in front of the structure. Predicting the correct failure modes (crushing, bending, and splitting or combined modes of failure) is desirable as well as the global force on the structure. However, this is not straightforward due to the complexity of the mechanical behavior of ice. It is facing some challenges such as, anisotropy (ice can be considered as a transversally isotropic material), inhomogeneity, and strain rate and pressure dependent response. Some of these key behaviors are considered on this study as a preliminary start for the further investigations as a part of the ColdTech project.

• Numerical simulation the bottom structures grounding test by LS-DYNA

  Ainian Zhang, Katsuyuki Suzuki - The University of Tokyo,

  Nonlinear finite element method (FEM) is a powerful tool for analyzing ship collision and grounding problems. The reliability of the numerical simulation results largely depends on the proper definition of problem and careful control of some critical parameters. The purpose of the paper is to study the effect of selected parameters on crashworthiness of the single-hull bottom structure due to raking. The quasi-static grounding process is simulated by the LS-DYNA code. The effects of the following parameters are considered: the boundary condition, the friction coefficient, shell element type, the residual stress and the material model. The influences of selected parameters are assessed by comparing the different results in the impact force and absorbed energy vs. penetration of rock model. Some suggestions are proposed for numerical simulation in finite element code LS-DYNA.

• Numerical Simulation Transcatheter Aortic Valve Implantation and Mechanics of Valve Function

  M.S. Hamid, Ph.D., Advanced Computational Systems LLC, Rochester, MI 48306

  As the older population increases, age-related diseases such as aortic stenosis is a common heart condition in which there is a thickening and calcium deposition in the aortic root and aortic valve leaflets. This results in a host of symptoms like angina, embolism, stroke and sudden death. Current default treatment for severe aortic stenosis is surgical aortic valve replacement. Mechanical and bioprosthetic heart valves are common choice for surgical replacement of the diseased valves. However, surgical intervention is extremely risky for a large population of frail patients. Transcatheter Aortic Valve Implantation (TAVI) is being used selectively as a percutaneous alternative to surgical aortic valve replacement. This is a very complex procedure and involves very coordinated team work. This procedure involves steps from valve crimping to implantation and monitoring. Computational simulations of the TAVI help evaluate the valve functioning. In present study, a step-by-step complex numerical simulations of the TAVI procedure including the stent crimping and balloon inflation are presented. The stent frame is assumed as stainless steel and the outer skirt is assumed as polyethylene material. The stent frame is modeled with 3D hexagonal finite elements and the skirt is modeled as thin shell elements with fabric material property. The valve leaflets are modeled as Mooney-Rivlin material. The results of valve crimping and blood flow during ejection phase are presented. The SPH technique is used in modeling the flow through the aortic valve. The stent deformation and the stresses induced due to crimping are presented. The normal and calcified leaflets opening are presented.. The LS-DYNA® multi-physics capabilities of fluid structure interaction is presented..

• Numerical Simulations in Vehicle Restraint System Development

  M. Šebík, M. Popovič (SVS FEM), M. Drdlová (Research Institute for Building Materials)

  Since 2016 there has been a research project going on which is focused on development of new design of portable road barriers with integrated anti-noise walls. The key feature of the new barrier design is a material selection for anti-noise panels. New panels made of wood and cement-bonded wood-chip material called Velox significantly improve noise absorption properties of the barrier. However, the question is: what are their qualities from mechanical point of view? And will such barrier be able to withstand crash tests required by the highest containment level, H4b according to EN1317 standard? Numerical simulations are being utilized in this research at all levels in order to reduce costs and to predict how particular design modifications influence restraint capabilities of the barrier. As a starting point there were crash test simulations with original barrier design performed and after achieving sufficient correlation between the simulations and the real crash tests, modified systems were designed and tested. Firstly, there were the new panels. From mechanical point of view, Velox is very complex material so an extensive investigation of its mechanical properties had to be performed. This investigation covered small scale tests (quasistatic and dynamic) and large scale dynamic tests as well. Based on the experiments there was an appropriate material model chosen and its parameters determined to faithfully describe behavior of the material. Since crash test simulations with the first Velox wall design identified several weaknesses, certain preventive measures had to be introduced. Besides design changes of the bottom part of the barrier, several kinds of Velox boards back face treatment were proposed in order to enhance resistance and keep overall integrity of the structure after crash load exposure. All these design changes are now being analyzed and further developed based on crash test simulations but also with regard to production processes and mobility of the barrier.

• NUMERICAL SIMULATIONS OF DUCTILE FAILURE IN EXTRUDED ALUMINIUM ALLOYS USING A COUPLED MODEL OF ELASTO-PLASTICITY AND DAMAGE

  O.-G. Lademo, O.S. Hopperstad, T. Berstad, M. Langseth - Structural Impact Laborator

  A test programme has been carried out to establish the mechanical properties of three extruded aluminium alloys. The investigated alloys exhibited significant anisotropy in strength, plastic flow and ductility. The anisotropy is mainly due to crystallographic texture, and an anisotropic yield criterion is needed to describe the mechanical behaviour. Several yield criteria were evaluated against the experimental data. The yield criterion Yld96 proposed by Barlat and co-workers was found to be superior with respect to accuracy for the actual aluminium alloys. In an attempt to model ductile failure of the investigated materials, a coupled model of elasto-plasticity and ductile damage was implemented in LS-DYNA for plane stress analysis with corotational shell elements. The material model combines the anisotropic yield criterion Yld96 with the associated flow rule, isotropic strain hardening and isotropic damage. The parameters defining the yield criterion and the strain hardening were determined from tensile tests and pure bending tests, while the damage parameters were identified using inverse modelling of tensile tests performed with purpose-made specimens. A series of biaxial tensile tests was also completed, and the results from these tests were used in an attempt to evaluate the constitutive model.

• Numerical Simulations of Dynamic Deformation of Air Transport Package PАТ-2 in Accidental Impacts

  Alexander A. Ryabov, Vladimir I. Romanov, Sergey S. Kukanov, Sergey G. Skurikhin - Joint Stock Company SarovLabs, Russia

  The PAT-2 package is designed by Sandia National Laboratories [1] for the safe transportation of plutonium and/or uranium in small quantities, especially as transported by air. The package consists of an outer container and an inner absorber. The outer container is made of 304 stainless-steel sheet metal. The inner absorber assembly consists of redwood and maplewood layers and is used for decreasing the mechanical loads onto the inner capsule with a radioactive material. The PAT-2 package is resistant to high-speed jet aircraft crash. That was verified by the experiments. The package was tested in several orientations and subjected to impacts at a velocity of >129m/s onto a flat unyielding surface. Some obtained results of the package dynamic deformations are described in [1]. It is also noticed in [1] that the worst impact orientation could not be proven by the stress analysis before the tests. That’s why it’s very important to conduct a numerical simulation of the package behavior in high-speed impacts to compare the numerical results with the experimental data. Such a numerical expertise opening “an internal deformation world” of the construction behavior allows understanding the weakest and the strongest features of the design and can show the ways on how to improve the structure. It’s also an additional experience of LS-DYNA® applications for such problems as well. The computer model description and the numerical calculations results of the dynamic deformations of the package subjected to top-end, bottom-end, top-corner, bottom-corner and side impacts at a speed of >129 m/s are presented in the paper. Furthermore, U.S. Legislation (U.S. Public Law 100-203) also requires that the foreign shipments of plutonium through U.S. airspace be able to withstand a worst-case aircraft crash, therefore the requirements for packages used for these applications is expected to be even more severe [2]. In accordance with this requirement, the stress analysis of the package at arbitrary impact speed of 200 m/s was performed using the computer model of PAT-2.

• Numerical Simulations of Vacuum Packed Particles using LS-DYNA

  P. Bartkowski, R. Zalewski (Warsaw University of Technology)

• Numerical Simulations of Vehicle Restraint Systems

  M. Šebík, M. Popovič, SVS FEM s.r.o., Czech Republic

  This paper provides an overview of the progress that has been achieved so far in the investigation of restraint abilities of portable road barriers with integrated anti-noise wall. The aim of this project is to develop finite element models that would be able to faithfully describe actual crash tests of several categories. Numerical simulations using these models could significantly reduce financial and time costs connected with the development process of these barriers. At the first step, the finite element models of the barrier with concrete anti-noise wall and two vehicles (TB81 - an articulated truck and TB51 – a bus) have been created and tested. Then a crash test simulation with the articulated truck model was performed and correlated with the experimental data from an actual crash test. The correlated aspects were: overall behavior of the vehicle and the barrier, maximum dynamic deflection of the top of the barrier and maximum permanent deflection of the bottom of the barrier. The simulation achieved fairly good agreement with the experimental data. The next step in this process will be a crash test simulation with the bus finite element model. Once the simulations of all required categories are able to faithfully describe the actual crash tests they will be used to predict restraint ability of another version of the barrier that is currently being developed. In this barrier there are panels made of cement-bonded wood-chip material called Velox used instead of concrete panels in the anti-noise wall. In order to be able to simulate new version of the barrier, material properties of Velox had to be determined and subsequently used to create a material model. This effort led to a material model that sufficiently matches experimental data obtained from a set of static and dynamic measurements. Dynamic material properties of Velox material will be further tested with Split Hopkinson Bar (SHB) method as the SHB testing device for large specimen (Φ 50 mm) is currently being developed in SVS FEM in cooperation with Research Institute for Building Materials, Brno. The last step before performing a full scale crash test simulation with Velox version of the barrier will be a punch test simulation of a whole Velox panel. Explicit solver of finite element program LS-DYNA® was chosen to obtain solutions of mentioned numerical problems.

• Numerical Simulations to Investigate the Efficiency of Joint Designs for the Electro-Magnetic Welding (EMW) of the Ring-shaft Assembly

  H. Kim, J. Gould (Edison Welding Institute), J. Shang (American Trim), A. Yadav, R. Meyer (Caterpillar Inc), Pierre L'Eplattenier (LSTC)

  In this study, numerical simulations on electro-magnetic welding (EMW) were conducted for dissimilar materials joint of the ring-shaft assembly. LS-DYNA® electromagnetism module was adopted to simulate the EMW process. Simulation results were correlated with the EMW experimental works with two different joint designs, single and double flared lap joint. Two different materials, aluminum 6061-T4 and copper, C40, were used for the driver ring material on the stationary steel shaft. LS-DYNA simulation model was used to investigate the effects of impact angle and velocity on surface-layer bonding and joining efficiency of the driver ring on a steel shaft. Analytical modeling was also conducted to estimate the magnetic pressure between the coil and the ring. Experimentally, a 90-KJ machine was used at different energy levels. From these experiments, the double flared lap joint showed better joint efficiency and the copper showed better adhesion than aluminum at same energy levels. The performance of joint was evaluated by push-off testing. A double flared copper ring at 81-KJ gave the best performance of joint, and exceeded the required axial thrust load requirement. From the metallographic analysis, the interface of joint did not show the metallurgical bonding, however, strong mechanical interlocking was achieved. This study demonstrates the viability of EMW process for dissimilar material joining.

• Numerical Structural Design and Optimization of Free-Form Hydrogen Vessels in the Context of Metal-Organic Frameworks

  Markus Bellmann, Ruben Krischler, Ruben Czichos, Peter Middendorf

  Development regarding storage solutions for hydrogen is crucial to enable its widespread adoption as a sustainable energy carrier especially in the mobility and transportation sector. The application of Metal-Organic Frameworks in carbon fiber composite wound pressure vessels leads to a reduction in operating pressures and allow both a cost and CO2 footprint reduction by enabling glass fiber as a valid material choice and the exploration of free form tank designs in order to better utilize challenging design spaces in automotive vehicles. This study explores the capabilities and limitations of these tank designs using numerical multi stage optimization in LS-OPT in conjunction with LS-DYNA, BETA CAE, MATLAB and Python for the fully automated, detailed optimization of the geometry and laminate of these tanks.

• Numerical Study of an Interrupted Pulse Electromagnetic Expanding Ring Test

  J. Imbert, M. Worswick (University of Waterloo)

  Light weighting of vehicle structures will play an important part in the efforts to reduce fuel consumption and enable alternatively powered vehicles. The use of aluminum alloys and advanced high strength steels is one potential way of achieving significant weight reductions in the short to medium term. One of the main challenges posed by these materials is their relatively poor formability when compared with traditional automotive steel alloys. High speed forming has been studied as a way of increasing the formability of these alloys, with promising results. The lack of accurate constitutive data and models for these materials at the strain rates encountered in high speed forming, which can exceed 1,000 s -1 , presents a significant challenge to their implementation. Expanding ring tests have been used to measure the stress strain response at materials at high strain rates. In principle, these tests generate a uniaxial tensile stress state within the ring. If the driving force is known and the acceleration of the sample can be measured, then the stress and strain response of the material can be obtained. Significant challenges need to be overcome to obtain stress-strain data from this test, namely understanding the induced forces, Joule heating and the actual stress distribution in the ring. An interrupted pulse electromagnetic expanding ring test is being developed at the University of Waterloo to study the high rate behaviour of sheet metals. The test minimizes the induced forces generated on the sample and can produce free flight conditions. Given the complex nature of the phenomena and the speed at which they occur, numerical simulations play a critical role in analyzing the test. This paper presents the results of a multi-physics numerical analysis of the test based on a 3-D simulations using LS-DYNA ® . This analysis has been done to determine the effect of Joule heating and the driving force on the data generated by the test.

• Numerical Study of the High Velocity Impact Response of Vehicle Armor Combination Using LS DYNA

  G. Başaran (FNSS Savunma Sistemleri)

  The aim of this work is to perceive if the outcome from a ballistic impact can be predicted beforehand with the help of material testing and finite element simulations. Use of refined numerical simulation are gaining more importance especially in extreme load cases. A numerical investigation of the ballistic performance of monolithic, double layered metallic plates made of either steel or aluminium or combinations ,were impacted by a 7.62-mm APM2 projectile at a velocity of 820m/s. The numerical models were developed using the explicit finite element code LSDYNA®. The effect of different metallic parts- thickness on the residual velocity of APM2 projectiles is examined. Three configurations of plate arrangements with different total thicknesses were used. Both aluminium target and projectile have been modelled as deformable bodies with Modified Johnson-Cook material model based on input parameters from literature[1].The predicted values of residual velocities were compared with the literature and a good correlation was found between the two.

• Numerical study on a new forming method for manufacturing large metallic bipolar plates

  David Briesenick, Maxim Beck, Kim Rouven Riedmueller, Mathias Liewald

  Fuel cell technology offers a sustainable power supply solution for heavy-duty vehicles, aviation and shipping as well as stationary application. Manufacturing of metallic bipolar plates (MBPP) as a key component of fuel cells is nowadays one of the main topics in production-based research and processing industry. One reason for this is that although stamping of thin stainless-steel foils enables an economic large-scale production of metallic bipolar plates, tooling and press technologies required for embossing and shear cut operations are highly demanding and thus continuously being developed. Particular challenges are posed by the embossing of the complex flow field structure, which can cause forming defects and pronounced springback phenomena.

• Numerical-Experimental Correlation of Mechanical Tests on Fiber-Reinforced Polyamide Composites

  A. Molaro, M. Lanzillo, F. Uimbardi, A. Causa, B. Villacci (SAPA)

  This work presents an experimental and numerical study of the mechanical behavior of polyamide 66 (PA66) filled with short glass fibers (GF) and short carbon fibers (CF), which are appealing materials for the development of active automobile safety devices. As the latter need to be validated through numerical simulations of crash tests, the study described herein is aimed at the determination of the elements that define the LS-DYNA® cards for the PA66-GF and PA66-CF composites. Firstly, such fiber-reinforced materials have been thoroughly characterized by performing tensile tests on specimens cut from injection-molded panels at different orientations relative to the preferential fiber direction (0°, 45° and 90°). Secondly, representative simulations of the experimental mechanical tests have been performed by developing in LS-DYNA® two- and three-dimensional models of the specimens and subjecting them to quasi-static tensile loads. The material model used to describe the behavior of short-fiber-reinforced thermoplastics is *MAT_NONLINEAR_ORTHOTROPIC (*MAT_040). Finally, the simulated stress-strain curves have been calibrated with the experimental ones; namely, the parameters of the numerical curves have been optimized to obtain a good interpolation of the experimental results. For both the PA66-GF and PA66-CF composites, two-dimensional modeling has provided a better correlation between numerical and experimental data in comparison with the three-dimensional one.

• NVH and Random Vibration Fatigue Analysis of a Landing Gears's Leg for an Un-Manned Aerial Vehicle Using LS-DYNA®

  Al-Bahkali Essam, Elkenani Hisham (King Saud University), Souli Mhamed (Universite de Lille)

  The present work concerns the new capability of LS-DYNA in solving Noise, Vibration and Harshness (NVH) and fatigue based on Power Spectrum Density (PSD) analysis. These new capability includes random vibration and high-cycle fatigue analysis in a random vibration environment. In this analysis, the cumultative damage ratio of a landing gear's leg for an Un-Manned Aerial Vehicle (UAV) is computed using material S-N (Stress-Number of cycles) fatigue curve. Dirlik method is used for the analysis of life time as it is proven to provide accurate results for large number of applications, both in automotive and aerospace industry. It is also compared to other methods that have been developed in LS-DYNA as well. The input acceleration PSD data are provided through measurements.

• Occupant Injury Criteria, a Complete Solution for the Evaluation of Occupant and Structural, Simulation and Physical Test Results in META

  Claes Ljungqvist, Jacob Wass, Nikos Tzolas, Peter Appelgren, Volvo Car Corporation, Volvo Car Corporation, BETA CAE Systems SA, BETA CAE Nordic AB

  For any type of simulation and after each solver run, the vast majority of the post processing actions for the evaluation of results and report generation are always the same. Particularly for Occupant Safety tests the increasing number of regulations, the use of different dummy types per regulation-test as well as the different vehicle variants that may exist and have to be tested, significantly increase the number of simulations and corresponding post-processing actions. Apart from this repetition, proven to be time consuming, cumbersome and prone to errors, another laborious issue is the comparison of the simulation with the physical test results.

• Occupant Injury Risk Assessment during a Car–to-End Terminal Crash under Crash Test Conditions and Extended Scenarios

  Yunzhu Meng, Costin Untaroiu (Virginia Tech)

  The safety performance of ET-Plus, the most common energy-absorbing guardrail end terminal used in the U.S., was evaluated based on the crash tests recommended by the National Cooperative Highway Research Program (NCHRP). However, while the NCHRP standards were updated to Manual for Assessing Safety Hardware (MASH) in 2009, the safety performance of ET-Plus was not re-evaluated by the updated tests. Also, the occupant injury was evaluated on the full-body level and no seatbelt or airbag usage was considered. Therefore, the main objectives of this study were to evaluate the safety performance of ET-Plus under the MASH test conditions and to assess occupant body-region injuries under varied impact conditions for the first time. Yaris car to ET-Plus crashes simulations were developed based on two sets of MASH test conditions to evaluate the safety performance of ET-Plus. Furthermore, extended scenarios were developed in this study to evaluate the occupant injury risk in varied impact conditions. Three impact velocities (80, 100, and 120 km/h), two impact angles (0, and 15 degrees), and two impact overlap (none, and 25% passenger-side) were used as the pre-impact condition parameters. In each simulation, Occupant Impact Velocity (OIV) and Occupant Ridedown Acceleration (ORA) were calculated and compared to the body-region injury probabilities. The body-region injury probabilities were calculated based on the kinematic responses of the dummy head, neck, and chest. The injury potential was evaluated (HIC, Nij, maximum chest deflection, and chest acceleration) and the severe injury probabilities were then assessed for head and neck injury, and chest injury. For the two simulations developed based on the MASH test conditions, the one with a small overlap (test 30) passes all the requirements while the other one (test 32) failed because the OIV longitudinal exceeds the threshold. Considering the extended scenarios, the average OIV longitudinal was observed to increase with pre-impact velocity: they were recorded as12.3, 12.6, and 14.0 m/s while the pre-impact velocity was 80, 100, and 120 km/h, respectively. Meanwhile, OIV longitudinal was observed to be a good predictor for chest injury while it cannot be used to predict head and neck injury. The OIV lateral was found to be correlated to the head and neck injury. However, it is not recommended to be used to do accurate predictions since the p-value is close to 0.05. On the other hand, the ORA, both longitudinal and lateral, were observed to have no predictability for either head and neck injury or chest injury. This study indicated that the ET-Plus may have the weak capability to protect the occupant during a vehicle to end terminal collision because it would fail MASH test 32 based on the simulation results. Meanwhile, OIV and ORA were observed to have a low capability to predict occupant body-region injuries. Only the OIV longitudinal has predictability for chest injury probability. Head and neck injury, which is a common occupant injury, cannot be assessed by any vehicle-based metrics. Therefore, the usage of dummies should be recommended to the current test requirements. The numerical simulation methods could also supplement the development of new crash tests with varied impact conditions and the optimization of the design of guardrail end terminals.

• Occupant Response in Rollover Crashworthiness Assessment of Cutaway Bus

  MohammadReza Seyedi, Grzegorz Dolzyk, Sungmoon Jung, Jerzy Wekezer,, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046

  The objective of this study is to assess the injury risk and rollover mechanism of cutaway bus during two rollover crash tests using finite element method. Based on two well-established test procedures, ECE-R66 and SAEJ2114, different rollover scenarios were conducted. The full finite element (FE) model of cutaway bus which was verified by pervious studies, and Hybrid III 50th male Anthropomorphic Test Device (ATD) were deployed to conduct the rollover test and calculating the severity of injuries. The computational analyses were carried out with using the LS-DYNA® nonlinear finite element code. Several simulations were performed with considering different initial conditions. The effects of drop height and initial velocity of rollover mechanism and passenger responses were measured. In addition, the interaction of the occupants and structural parts were quantified quantitatively and qualitatively. The capability of two test procedures to predict the injury risk were discussed. Results show that the initial condition of the rollover test procedures has the significant influence on occupant response. For instance, the results for the dolly rollover test indicate that the occupant response and rollover mechanism were highly affected by the initial velocity rather than drop heights. The outcomes of this study also provide a better understanding of kinematics of occupants and cause of the injuries during the rollover crash of buses. The results also showed that the head, neck and chest injuries are the most common type of injuries that occupants experienced. Partial ejection due to broken side windows and direct impact between head, chest, and shoulder with ground were found the main causes of injuries. Furthermore, it is recommended that to improve the countermeasures of rollover safety assessment the interaction of the occupants and structural components should be considered.

• ODB-10M New Topcrunch Benchmark Data

  Mitsuhiro Makino and Shota Yamada - DYNAPOWER corp

  New Benchmark model ODB-10M is 10 million elements model, which consist of refined NCAC Taurus model and LSTC shell ODB barrier model. Refined NCAC Taurus model is 9 million elements of type16 shell elements and type2 solid elements, and *CONSTRAINED_SPOTWELD is changed to *CONTACT_SPOTWELD with beam. In LSTC shell barrier, type10 shell element is changed to type16 shell element in order to avoid negative hourglass energy. We also discuss about the domain decomposition.

• Oil-canning Simulation of Outer Panel and Influence of Stamping Results

  Y. Hu (Chrysler Group LLC), J. Sun, X. Zhu (LSTC)

  Abstract Oil-canning test is one of the most important measurements for outer panel stiffness. The methodology to analyze oil-canning of automotive outer panels using LS-DYNA® is studied and presented. Dynamic explicit method is used for stamping simulation and static implicit method is used for oil-canning simulation. The stamping results are carried over to oil-canning simulation. In one of the studies, displacement controlled indentation was applied to the panel and the contact force between the indenter and the panel was recorded. The Riks method was used in an alternative approach. Both approaches give the similar critical oil-canning resistance force which has good agreement with the measurement data. The influences of stamping results, particularly thickness reduction and stress status, on oil- canning resistance were also studied. Firstly, oil-canning simulations with stamping result vs. without stamping result were compared. It’s been found that stamping results could lower the oil-canning resistance force. The oil-canning analyses of panel with various levels of stamping results were also compared. Based on the research, the procedure for oil-canning simulation with LS-DYNA® was established to help optimize product and process designs satisfying with stiffness requirements.

• On Accuracy and Stability of Implicit Time Integration Schemes for Rotating Structures

  Thomas Borrvall (DYNAmore Nordic AB), Mike R. Lawson (Imperial College)

  In the context of finite element analysis, the Newmark time integration scheme is the most commonly used for nonlinear implicit dynamic applications. While it is characterized by unconditional stability and energy conservation, it is also prone to numerical instability when the models are subjected to rotational motion. To this end, LS-DYNA® offers a selection of alternate integration schemes to remedy this deficiency; Bathe, HHT (Hughes-Hilber-Taylor) and FRD (Finite Rotational Dynamics). The intention with this paper is to tentatively discuss these instabilities and investigate to what extent they can be resolved by incorporating more sophisticated schemes.

• On Adaptive Finite Element Analysis in Structural Dynamics of Shell-Like Structures - A Specific View on Practical Engineering Applications and Engineering Modelling

  Karl Schweizerhof - Universität Karlsruhe / DYNAmore GmbH, Stephan Kizio - Universität Karlsruhe

  Adaptive Finite element analysis in structural analysis has reached a fairly mature status; however, in practice only fairly little is visible in engineering applications. This contribution gives an overview over some major aspects with a specific focus on structural dynamics of shell-like structures. Adaptive analysis in structural mechanics is mainly focusing on static problems where a large number of linear and nonlinear tasks in 3D continuum problems as well as in shell problems have been tackled. The developed procedures show really considerable improvements for the executed numerical problems. In statics on one side the competition among the methods is between low and high order approximation – the h- and p- or hp-enhancement and among error estimation between global and local estimation. For a good overview over the subject for a large number of problems it is referred to [11], for some mathematical background see [2]. For some simple benchmark problems the differences between the various approaches as presented in [5]. More recent developments are concerned with time dependent problems thus we are focusing here on structural dynamics [10]. In statics - linear or nonlinear – the spatial error distribution is the dominating quantity whereas in dynamics the consideration of the spatial error distribution over the complete considered time range and as well the consideration of the error due to time integration is needed. Here the consideration of dual problems – known in statics from the Betti-Maxwell principle and extended here with the according reciprocity idea, the Graffi-theorem [1] - allows checking the error in specific quantities at certain points in time, the so-called goal-oriented error computation or local error computation [3] [4]. On the basis of such error estimations, in principle, the adaptive modification of the finite element mesh as well as the time step is possible. However, while in a semi-discretization approach the time step could be fairly easily adjusted – which is frequently done in the so-called explicit FE programs using the central difference scheme - the modification of the finite element mesh introduces major problems. First the data have to be properly mapped between meshes avoiding non-physical artifacts and second the dual error estimation scheme has to take into account different time steps and meshes. Both actions introduce further errors into the analysis which can hardly be judged. In addition the effort for the numerical analysis concerning the computation as well as the required storage becomes overly large [6] leading to the conclusion that adaptive analysis of real world problems based on dual error estimation cannot be handled - at least with the current computer environment. Thus the focus of this contribution is on a discussion first on the importance of different parts of the error estimation and on the adaptive procedure and second how the major ingredients of the adaptive duality based analysis for practical engineering problems - restricting to shell problems - can still be used, regaining efficiency [7]. For some classes of shell type problems some simplifications can be suggested while still improving the quality of the analysis considerably by adaptive procedures [8]. In structural dynamics also eigenmodes and eigenvalues are important, thus improvements concerning these are also briefly discussed [9] [8]. Obviously the dominating quantity for achieving good results applying finite element methods in structural mechanics is a consistently refined mesh; not unexpected for high frequency excitations and interest of the engineers in these almost uniformly refined meshes with high mesh densities are required. It is shown, how the developed schemes can be applied to homogeneous problems and the limits concerning real world engineering models which include a large number of violations concerning standard continuum mechanics are presented. Also the procedures implemented in LS-DYNA [12], [13] for adaptive analysis are discussed with the background set above. Further some model adaptivity for large structural computations where some parts are – at least in some early states of the analysis – hardly deforming. This effect can be used to introduce rigid bodies in the analysis; the question then arises, how this can be handled. References

• On Adaptive Finite Element Analysis in Structural Dynamics of Shell-Like Structures - A Specific View on Practical Engineering Applications and Engineering Modelling

  Karl Schweizerhof - Universität Karlsruhe / DYNAmore GmbH, Stephan Kizio - Universität Karlsruhe

  Adaptive Finite element analysis in structural analysis has reached a fairly mature status; however, in practice only fairly little is visible in engineering applications. This contribution gives an overview over some major aspects with a specific focus on structural dynamics of shell-like structures. Adaptive analysis in structural mechanics is mainly focusing on static problems where a large number of linear and nonlinear tasks in 3D continuum problems as well as in shell problems have been tackled. The developed procedures show really considerable improvements for the executed numerical problems. In statics on one side the competition among the methods is between low and high order approximation – the h- and p- or hp-enhancement and among error estimation between global and local estimation. For a good overview over the subject for a large number of problems it is referred to [11], for some mathematical background see [2]. For some simple benchmark problems the differences between the various approaches as presented in [5]. More recent developments are concerned with time dependent problems thus we are focusing here on structural dynamics [10]. In statics - linear or nonlinear – the spatial error distribution is the dominating quantity whereas in dynamics the consideration of the spatial error distribution over the complete considered time range and as well the consideration of the error due to time integration is needed. Here the consideration of dual problems – known in statics from the Betti-Maxwell principle and extended here with the according reciprocity idea, the Graffi-theorem [1] - allows checking the error in specific quantities at certain points in time, the so-called goal-oriented error computation or local error computation [3] [4]. On the basis of such error estimations, in principle, the adaptive modification of the finite element mesh as well as the time step is possible. However, while in a semi-discretization approach the time step could be fairly easily adjusted – which is frequently done in the so-called explicit FE programs using the central difference scheme - the modification of the finite element mesh introduces major problems. First the data have to be properly mapped between meshes avoiding non-physical artifacts and second the dual error estimation scheme has to take into account different time steps and meshes. Both actions introduce further errors into the analysis which can hardly be judged. In addition the effort for the numerical analysis concerning the computation as well as the required storage becomes overly large [6] leading to the conclusion that adaptive analysis of real world problems based on dual error estimation cannot be handled - at least with the current computer environment. Thus the focus of this contribution is on a discussion first on the importance of different parts of the error estimation and on the adaptive procedure and second how the major ingredients of the adaptive duality based analysis for practical engineering problems - restricting to shell problems - can still be used, regaining efficiency [7]. For some classes of shell type problems some simplifications can be suggested while still improving the quality of the analysis considerably by adaptive procedures [8]. In structural dynamics also eigenmodes and eigenvalues are important, thus improvements concerning these are also briefly discussed [9] [8]. Obviously the dominating quantity for achieving good results applying finite element methods in structural mechanics is a consistently refined mesh; not unexpected for high frequency excitations and interest of the engineers in these almost uniformly refined meshes with high mesh densities are required. It is shown, how the developed schemes can be applied to homogeneous problems and the limits concerning real world engineering models which include a large number of violations concerning standard continuum mechanics are presented. Also the procedures implemented in LS-DYNA [12], [13] for adaptive analysis are discussed with the background set above. Further some model adaptivity for large structural computations where some parts are – at least in some early states of the analysis – hardly deforming. This effect can be used to introduce rigid bodies in the analysis; the question then arises, how this can be handled. References

• On Airbag Simulation in LS –DYNA with the use of the Arbitrary Lagrangian - Eulerian Method

  Dmitri Fokin, Nitin Lokhande, Lars Fredriksson - Altair Engineering GmbH, Germany

  In the present paper a basic finite element model of an ALE thorax side airbag with a simplified gas generator will be considered. In particular, it will be discussed how to define boundary conditions and properties of the inflating gas. A possible general approach to ALE airbag validation to fit results of a standard body block test will be described. Finally numerical results for a push-away test for an ALE and corresponding CV airbag will be compared.

• On Applications of Adaptive Strategies for General Shell Structures in Crashworthiness Analysis Using LS-DYNA

  Karl Schweizerhof - CAD-FEM GmbH, T. Münz, O. Graf, M. Walz - CAD-FEM GmbH, Chen Tsay, J. O. Hallquist - Livermore Software Technology Corporation

  Adaptive strategies are nowadays applied in a rather standard fashion in linear static analyses where reliable global and local estimators are available for many problems [22],[23],[5]. Con- siderable progress has been achieved for nonlinear problems [14], [4][8][9][13][17], also in- volving contact [21], because fairly reliable estimators exist, resulting in efficient procedures. However, for transient loading only limited success has been achieved so far [19],[20],[15],[11][12]. This is due to the fact that inertia effects and time integration schemes introduce additional complexity and approximations. As a result, no reliable error estimation is yet possible for large deformation dynamic problems such as metalforming and crashwor- thiness analyses. Adding to the difficulties is the complexity of the structures to be analyzed. Crashworthiness models violate, at least in parts, the continuum mechanics approximations such as multiple shell connections, spotwelds or shell-beam connections. Although proposals for the adaptive static analysis of composite shell connections exist [15], these cannot easily be applied to dynamic problems. In particular, the a-priori definition/detection of such non- continuous parts is a difficult task and contact regions need high resolution to achieve reason- able error estimation. Furthermore, there is no reliable error estimation possible for the very efficient and simplified shell elements with reduced integration and hourglass control - the "work-horse" in crashworthiness analysis. Nevertheless, some standard error indicators have been implemented and tested for some large deformation problems in LS-DYNA with some success [9]. As a consequence, for very general, large scale crash models in industrial practice currently only adaptive procedures remain which use error indicators based on simple ideas such as geometrical relative deformations [3]. These methods have to be combined with adaptive meshing schemes which allow only a certain level of refinement due to efficiency reasons. Additionally, the refinement has to be restricted to various points in time. In particular for deep drawing applications, it often appears to be very beneficial to step back in time and re- start the analysis with an adapted mesh at a previous point in time. LS-DYNA [7] has been recently enhanced by the capability to allow adaptive schemes for certain type of shell connections. In addition, it was observed that it is very effective to refine the mesh in metalforming applications prior to contact with small radii. The introductions of these so-called look-ahead algorithms limit the number of back-steps in time to almost zero. This contribution highlights these new features in LS-DYNA. The numerical examples range from metalforming analysis, simple buckling analysis of a structural member to a complex crashworthiness model. The merits and the limits of the currently available methods in LS- DYNA are illustrated. This may lead to further insight on how future efficient error estimators could be developed on a sound mathematical basis, even for large deformation problems with high complexity. Some hints are given to use the implemented indicator and the adaptive meshing efficiently improving the quality of the analyses.

• On Automatic Crash Model Translation

  E. Di Pasquale (SimTech/ Université de Valenciennes)

  This paper discusses some issues relevant to automatic crash model translation (conversion), based on SimTech experience. Automatic crash model conversion is in many ways similar to automatic language translation. The first level of conversion is “literal” translation, where each entity in the source model is translated into a corresponding entity in the target model. This issue is already complicated because such a target entity may not exist or may not be uniquely defined.

• On Closing the Constitutive Gap Between Forming and Crash Simulation

  F. Neukamm, M. Feucht, K. Roll - Daimler AG, Germany, A. Haufe - DYNAmore GmbH, Germany

  With increasing requirements on crashworthiness, and light-weight car body structures being a central issue in future automotive development, the use of high strength steel qualities has become wide-spread in modern cars. Since these materials often show significantly lower ductility than conventional steels, it is of great importance to precisely predict failure under crash loading conditions. Hence constitutive models in crashworthiness applications – as for instance the Gurson/Johnson-Cook model which is applied widely at Daimler AG – need to be initialized with correctly determined internal variables mapped from a corresponding sheet metal forming simulation. Here two principle ways could be used theoretically: On the one hand different understanding of damage and failure in crashworthiness and sheet metal forming applications may be unified by a generalized incremental stress state dependent damage model (GISSMO). This approach can be considered as an attempt to replace the currently used FLD for the failure description in forming simulations. Furthermore, an advantage would be the inherent ability to account for load-path dependent failure behavior. On the other hand the already applied Gurson model in crash simulations may be fed by an estimation of the internal damage value from the forming simulation. The idea here would be to perform the forming simulation with a state-of-the-art anisotropic material model like e.g. the Barlat model, with a simultaneously executed estimation of Gurson’s damage evolution law. The present paper will enlighten these two possible approaches. Furthermore it will be shown that damage prediction in metal forming processes and subsequently the use of the results as initial damage values in crash simulations is possible and necessary to predict structural failure in crashworthiness simulations.

• On Composite Model Calibration for Extreme Impact Loading Exemplified on Aerospace Structures

  A. Haufe, S. Cavariani, Chr. Liebold, T. Usta (DYNAmore GmbH), Th. Kotzakolios, E. Giannaros, V. Kostopoulos (University of Patras), A. Hornig, M. Gude (Technical University of Dresden), N. Djordjevic, R. Vignjevic (Brunel University London), M. Meo (University of Bath)

  This contribution will present some simulation related work carried out within a public funded Horizon2020 project of the European Community. Focus is set on composite damage and fracture modelling available in the finite element solver LS-DYNA® and the constitutive models developed within the project. Based on use-cases identified within the project EXTREME, experimental testing and numerical modeling techniques for continuous fiber reinforced aircraft structures such as turbine blades and wing sections are shown. The contribution will showcase results of work packages of the project, such as physical tests conducted to determine the various model parameters which are needed to accurately describe the anisotropic material behavior on a macroscopic length scale that is considered being state-of-the-art in numerical simulations.

• On Constitutive Equations for Dummies

  B. Feng, J. Hallquist - LSTC

  Constitutive equations, which may be used for modeling dummies during impact, are presented. In addition, a unified constitutive equation, for dummies and rubber-like materials, is presented. The new constitutive equation applies to elastic, viscoelastic, incompressible as well as compressible materials. Some special cases, e.g., neo-Hookean, Mooney-Rivlin, Ogden incompressible, Ogden compressible, and many currently used constitutive equations, are given to demonstrate the versatility of the new constitutive equation. The material constants for the constitutive equation can be determined from uniaxial and biaxial tests. A constitutive equation for chronorheological materials that describes the aging and viscoelastic behaviors of elastomers is presented. A recurrence formula, that saves computing time and requires no data storage space for time-dependent physical quantities for viscoelastic constitutive equations, is also mentioned briefly. These constitutive equations are used in numerical analyses for selecting materials to improve the performances of a dummy model used in car-crash simulations. Some results are shown. Future work is mentioned briefly.

• On Constitutive Equations for Dummies

  B. Feng, J. Hallquist - LSTC

  Constitutive equations, which may be used for modeling dummies during impact, are presented. In addition, a unified constitutive equation, for dummies and rubber-like materials, is presented. The new constitutive equation applies to elastic, viscoelastic, incompressible as well as compressible materials. Some special cases, e.g., neo-Hookean, Mooney-Rivlin, Ogden incompressible, Ogden compressible, and many currently used constitutive equations, are given to demonstrate the versatility of the new constitutive equation. The material constants for the constitutive equation can be determined from uniaxial and biaxial tests. A constitutive equation for chronorheological materials that describes the aging and viscoelastic behaviors of elastomers is presented. A recurrence formula, that saves computing time and requires no data storage space for time-dependent physical quantities for viscoelastic constitutive equations, is also mentioned briefly. These constitutive equations are used in numerical analyses for selecting materials to improve the performances of a dummy model used in car-crash simulations. Some results are shown. Future work is mentioned briefly.

• On Constitutive Equations For Elastomers And Elastomeric Foams

  William W. Feng, John O. Hallquist - Livermore Software Technology Corporation

  The Hill-Ogden elastic constitutive equation for incompressible and compressible rubber-like materials is presented. The derivation and computer programs to determine the material constants for these equations from uniaxial and biaxial tests are included. These constitutive equations and the computer programs for determining the material constants have been implemented into LS-DYNA. A few examples are shown. Some special cases are given to demonstrate the versatility of these constitutive equations. The Mooney-Rivlin constitutive equation is a special case. The Feng-Christensen viscoelastic foam model in one-dimensional compression, developed in 1986, can be written in a mathematical form and implemented in finite element codes.

• On Demand Licensing with LS-DYNA

  U. Göhner (DYNAmore)

  The LS-DYNA simulation software is used on different High-Performance-Computing platforms since many years. Most of the users have access to in-house Cluster systems running LS-DYNA in the MPP-version on up to several 100s of Cores and an appropriate number of licenses to use their hardware effectively [1]. In recent years there was increasing demand inside the LS-DYNA user base for a flexible and efficient offering of software licenses both for on-premise hardware and for Cloud-based HPC-platforms. Since 2016 DYNAmore and LSTC offer a flexible and cost-efficient pay-per use licensing scheme. This licensing scheme is being implemented and can be accessed through LSTC and DYNAmore, who are responsible for the development and distribution of the LS-DYNA simulation software. In this paper the different licensing schemes are being presented and practical experiences with the new LS-DYNA pay per use licensing concept are compared to other licensing possibilities. In addition the usage of LS-DYNA on Cloud-based infrastructure is shown. Advantages and disadvantages are discussed for different configurations and scenarios involving both SMEs and large organizations from automotive and other industries.

• On Fracture Criterion of Titanium Alloy under Dynamic Loading Conditions

  Pavel A. Mossakovsky, Fedor K. Antonov - Moscow State University, Anatoly M. Bragov, Alexander Yu. Konstantinov - State University of Nizhni Novgorod, Mikhail E. Kolotnikov, Lilia A. Kostyreva - FSUE "Gas Turbine Engineering Researh and Production Center-Salut"

  One of the most important factors in ensuring the adequacy of the mathematical modeling of limiting states of structures is the choice of the material local fracture criterion and accurate determination of its parameters. The paper discusses some traditional approaches to the construction of local failure criteria of metals under dynamic loading, methods of their parameters identification, as well as the development of these approaches on the example of impact penetration problem. The work focuses on the possibility of modeling viscous and brittle types of fracture within a single deformation type criterion, while the dependence of fracture strain on the stress triaxiality ratio can became complicated and nonmonotonic. The quality of the considered criteria is determined by comparing the results of virtual simulation with the data of full-scale experiments that implement various types of stress state and failure mechanisms. The results of full-scale and virtual compression, tension and penetration dynamic tests of the titanium alloy samples are given. Virtual experiments were conducted using nonlinear LS-DYNA code.

• On Interply friction in Prepreg Forming Simulations

  S. Kumaraswamy (Volvo), A. Dutta (KTH), M. Landervik, A. Bernhardsson (DYNAmore Nordic), M. Åkermo (KTH)

  The usage of composite materials in automotive body structures has the potential of reducing weight and thereby improving energy efficiency of the vehicles. Two key factors that limit their usage are long cure time for the material and the lack of simulation support. The recent development of snap-cure or rapid-cure prepregs can address the former problem. For the latter, LS-DYNA simulations can support the design of composite parts and production process which can improve both their structural properties and manufacturability, avoiding the economic and environmental costs of trial and error used today to obtain defect free parts. This paper concerns the simulation of the forming of parts using unidirectional (UD) carbon fiber prepreg.

• On Mooney-Rivlin Constants for Elastomers

  W. W. Feng, J. O. Hallquist (LSTC)

  The Mooney-Rivlin constitutive equation for rubber is W= C1(I1-3)+C2(I2-3) where material constants C1 and C2 must be determined through tests. The constant C1 can be determined by uniaxial tension or compression tests; however, C2 cannot be determined accurately by uniaxial tension or compression tests. In order to determine C, biaxial tests must be performed. A biaxial test, inflation of a circular 2membrane, is presented in detail here for determining both C1 and C2 .

• On Parameter Identification for the GISSMO Damage Model

  J. Effelsberg, A. Haufe (DYNAmore GmbH), M. Feucht, F. Neukamm (Daimler AG), P. Du Bois (Consultant)

  In order to improve predictiveness of crashworthiness simulations, great effort has been made regarding the treatment of crack formation and propagation. To achieve this, a consistent prediction of pre-damage, accumulated during manufacturing of a sheet-metal part, can help to improve accuracy. The constitutive models used for crash simulations are usually isotropic and based on the von Mises flow rule or the Gurson, Tvergaard & Needleman approach. For forming simulations, a more sophisticated and anisotropic description of yield loci – often based on the Hill or Barlat (1989) criteria – is considered important, which makes it necessary to use different constitutive models for both parts of the process chain. A damage model suitable to be used for both disciplines therefore has to be able to correctly predict damage regardless of the details of the constitutive model formulation. To fill this gap the damage model GISSMO (Generalized Incremental Stress-State dependent damage MOdel) has been developed at Daimler and DYNAmore (Neukamm et al. (2009), Haufe et al. (2010)). It combines proven features of damage and failure description available in crashworthiness calculations with the possibility of mapping various history data from sheet metal forming to final crash loading. The meanwhile carried out applications in everyday simulation work show excellent results based on carefully fitted material parameters. The present paper will focus on the parameter identification for the GISSMO damage model in crashworthiness simulation. A correct indication of damage and failure requires material data gained from several experimental tests. Starting from the treatment of the raw data, a procedure will be given, that shows how to calibrate the elastic-plastic behavior. In the following, a method is introduced which allows to capture damage and failure characteristics of a material. Step by step the determination and validation of particular GISSMO parameters will be discussed from a practical point of view. The objective is to give a complete overview of the calibration of a GISSMO material card.

• On Predicting Lower Leg Injuries for the EuroNCAP Front Crash

  Thomas Hofer - Altair Engineering GmbH, Peter Karlsson - Saab Automobile AB, Niclas Brännberg - Altair Engineering AB, Lars Fredriksson - Altair Engineering GmbH

  Validation of occupant lower leg injury performance is a difficult procedure due to the complex interaction between occupant and vehicle structure. As a starting point, a carefully validated structural model is crucial to ensure the accurate load of the occupant model in terms of acceleration and applied forces. However, even after a tedious validation of structural performance and occupant environment, the calculated tibia values might still deviate from the test results. Some of these deviations may be caused by restrictions in the occupant model fidelity. This becomes evident in an offset-crash simulation (EuroNCAP), since the complex force behaviour (x, y, and z- components) do not seem to be reproduced by existing occupant models to 100% satisfaction. Especially the dummy joint representation for the ankle, knee and pelvis might cause deviations between the occupant model and the test. Modifications of joint parameters were done to demonstrate a significant potential in the improvement of the fidelity of the occupant model and to bring the tibia injury criteria closer to the test results. This paper presents a detailed numerical analysis to point out the discussed difficulties and proposes possible approaches for a more realistic prediction of tibia values in the case of the EuroNCAP front crash. The proposed changes in this paper will not replace the need to permanently improve the standard FE dummies, but should be seen as a part of the discussion in order to improve the fidelity of the standard dummies in the future.

• On Predicting Lower Leg Injuries for the EuroNCAP Front Crash

  Thomas Hofer - Altair Engineering GmbH, Peter Karlsson - Saab Automobile AB, Niclas Brännberg - Altair Engineering AB, Lars Fredriksson - Altair Engineering GmbH

  Validation of occupant lower leg injury performance is a difficult procedure due to the complex interaction between occupant and vehicle structure. As a starting point, a carefully validated structural model is crucial to ensure the accurate load of the occupant model in terms of acceleration and applied forces. However, even after a tedious validation of structural performance and occupant environment, the calculated tibia values might still deviate from the test results. Some of these deviations may be caused by restrictions in the occupant model fidelity. This becomes evident in an offset-crash simulation (EuroNCAP), since the complex force behaviour (x, y, and z- components) do not seem to be reproduced by existing occupant models to 100% satisfaction. Especially the dummy joint representation for the ankle, knee and pelvis might cause deviations between the occupant model and the test. Modifications of joint parameters were done to demonstrate a significant potential in the improvement of the fidelity of the occupant model and to bring the tibia injury criteria closer to the test results. This paper presents a detailed numerical analysis to point out the discussed difficulties and proposes possible approaches for a more realistic prediction of tibia values in the case of the EuroNCAP front crash. The proposed changes in this paper will not replace the need to permanently improve the standard FE dummies, but should be seen as a part of the discussion in order to improve the fidelity of the standard dummies in the future.

• On Rollover Simulations of a Full-sized Sedan

  Ronald F. Kulak (RFK Engineering Mechanics Consultants LLC)

  Rollover crashes are responsible for many occupant injuries and fatalities. Rollover crash fatalities account for 36 percent of total fatalities for passenger cars and light trucks. Front seat occupants are vulnerable to head, neck and thoracic injuries resulting from impact with the collapsing roof structure. Modeling and simulation on parallel computing platforms using state-of-the-art software – such as LS-DYNA® – is an attractive and economical approach for studying the structural responses of the vehicle and occupant to rollover events. This paper presents simulations of rollover events of a full-sized sedan subjected to several initial vehicle orientations and front occupant positions. The National Crash Analysis Center database provided the finite element model for the full-size sedan. The front-seat occupant model is the Hybrid III finite element model developed by Livermore Software Technology Corporation, which represents the 50% male anthropomorphic test device (ATD). Thus, this study makes use of a single software platform for analyses of both the vehicle and occupant – leading to efficient computations. The current work focused on Single Event Single Rollovers (SESR). Several case studies are presented, and one case simulated a previously performed test using the Controlled Rollover Impact System (CRIS). The first case (far side impact) matched the CRIS Test 51502 initial release conditions, and the numerical simulations match the kinetic conditions when the vehicle contacted the ground – as calculated by rigid body dynamics. The second case looked at near side impact, and the third case looked at far side impact but with a 10 degree pitch angle. Results show that the largest neck forces occur for near side impact. Comparison of the first case simulation results with CRIS Test 51502 is examined for suitability of validating the finite element models to rollovers.

• ON TECHNIQUES FOR SIMULATING EFFECTS OF CAVITATION ASSOCIATED WITH THE INTERACTION BETWEEN STRUCTURES AND UNDERWATER EXPLOSIONS USING LS-DYNA

  Q.W. Ma, D.J. Andrews - University College London

  In this paper, a two-step technique is suggested to reduce the reflection of shock waves from a truncated boundary without significantly smearing the incident shock wave and to suppress spurious oscillations without significantly affecting accuracy. By comparing the results for a one-dimensional case with a wellknown analytical solution, it is shown that the technique works very well.

• ON THE APPLICATION OF LS-OPT TO IDENTIFY NON-LINEAR MATERIAL MODELS IN LS-DYNA

  David J. Benson,Morten R. Jensen - University of California, San Diego, Nielen Stander - Livermore Software Technology Corporation, Kenneth J. Craig - University of Pretoria

  A response surface optimization algorithm for structural material or parameter identification is evaluated. The algorithm used is the Successive Response Surface Method (SRSM) available in LS-OPT. To illustrate the robustness of SRSM as a material identification tool, two test cases are presented. The first concerns the identification of the power-law material parameters of a simple tensile test specimen. The second test case involves the identification of a model to characterize the brittle damage in a composite laminated structure. It is shown that SRSM is an effective tool for material parameter identification involving strongly nonlinear materials.

• On the Experiences of Adding a Complex User-Material-Model to LS-DYNA

  G. S. Kalsi (AWE)

  LSTC’s DYNA codes (both SMP and MPP) have been extensively used at AWE over a period of many years since they represent state-of-the art computational analysis capability which is required for simulating most of our complex problems. Occasionally there is a requirement to enhance existing code capabilities. An example is a need to improve the simulation of the constitutive behaviours exhibited by Polymer-Bonded Explosives (PBXs). Most polymer-bonded explosives are dual-phase composites consisting of an explosive crystalline filler material bonded in an elastically softer polymer matrix, which results in a very complex heterogeneous material. This heterogeneity, and the non-linear properties of the matrix, can lead to very complicated constitutive responses being generated when a PBX is loaded. PBXs possess unequal properties in tension and compression, and show marked strain-rate and temperature dependency. In the explosives arena, it is generally the energetic response of PBXs that forms the subject of in-depth studies, particularly from a viewpoint of safety assessments, e.g. accidental insults such as shock loading or fragment impact. The treatment of PBXs as structural, load bearing materials is less well investigated, for the primary purpose of a PBX is to act as an energetic source, rather than as a constructional material. However, there can be occasions when the structural response of a PBX needs to be well understood and controlled, and this new material model, known as GPM (Generic Polymer Material), was developed for this purpose. The GPM model is a damage-based material model that can simulate some of the complex constitutive responses displayed by PBXs, with a particular emphasis on creep and viscous response. This paper will briefly describe the formulation and application of this model, but the focus will be on the implementation of this material model into the LS-DYNA codes as a user-material-model. This was a non-trivial exercise and its implementation required a good deal of effort, together with some internal code changes by LSTC to their codes in order for the model to function correctly, since the user-material-model interface was found to be inadequate to accommodate a complex, non- linear material model’s requirements. Our experiences will be of potential benefit to other users who might find themselves in a similar situation.

• On The Feng Failure Criterion For Composites

  William W. Feng, John O. Hallquist, David J. Benson (LSTC)

  In this paper, the criterion is evaluated with experimental data for a boron/epoxy, symmetrically balanced, angle-ply laminate. The results prove that the failure states obtained by the criterion agree with the experimental data. Furthermore, the criterion also predicts whether the failure of a composite is due to matrix or fiber. The advantages for Feng failure criterion over other criteria are summarized, and the criterion is implemented into LS-DYNA for composite materials.

• On the Influence of Shell Element Properties on the Response of Car Model in Crash Test

  S. Burzyński, K. Wilde, D. Bruski, J. Chróścielewski (Gdańsk University of Technology)

  In this report we address the issue of selection of control card values and its influence on the behavior of the Ls-Dyna car model in collision test. It is shown that the shear factor coefficient plays substantial role on the overall course of the simulated event.

• On the Optimization of the Punch-Die Shape: An Application of New Concepts of Tools Geometry Alteration for Springback Compensation

  A. Accotto, G. Anedda, M. Sperati, R. Vadori - Altair Engineering Srl

  This work here presented concerns the activities of stamping tools alterations of an automotive component done thanks optimization technologies. The process of nominal geometry alteration of a complete stamping die is traditionally based on the experience of the try-out people who manually modify the tools in order to compensate geometrical differences due to springback under a Trial-and-Error approach and often the restroking die needs so substantial modifications to lead to be partially re-designed . With the introduction of new steels, high tensile steels with considerable springback effects, this approach become more and more difficult. Trial and error techniques used in the reality in the try-out phase now are possible in the development phase thanks to morphing technologies in HyperForm. But an innovative technique, developed at Altair Engineering, give the possibility to proceed automatically and systematically: the approach, general and flexible, is based on a orthonormal base of deformation functions that allows the automatic management of the geometry alteration of the die. Not least the principle to obtain a small geometry error after the cutting stages, before the restroking stage. The geometry alteration are hence applied on the draw tools. The process is automatically managed by an optimization algorithm in Altair HyperStudy, who manages the geometrical parameters who define the die shape in order to converge to the optimal die shape. This paper shows how the morphing approach and the automatic deformation function approach converge to the same solution and the improvements obtained in the reality.

• On the Parameter Estimation for the Discrete-Element Method in LS-DYNA®

  Nils Karajan (DYNAmore GmbH), Zhidong Han, Hailong Teng, Jason Wang (LSTC)

  The goal of this contribution is to discuss the assumptions made when modeling granular media with the discrete-element method (DEM). Herein, particular focus is drawn on the physical interpretation of the involved material parameters of the DEM in LS-DYNA. Following this, the influence of each parameter on the bulk behavior of granular media is investigated and different possibilities to estimate these parameters are presented.

• On the Performance and Accuracy of Enhanced Particle Finite Element Method (PFEM-2) in the Solution of Biomedical Benchmarks

  Chien-Jung Huang, Facundo Del Pin, Iñaki Çaldichoury, Rodrigo R. Paz (LST LLC, ANSYS)

  The numerical methods can be helpful on the R&D of medical devices to reduce the costly and lengthy process that clinical trials take for the US Food and Drug Administration (FDA) to approve a medical device. The FDA and academia are working together to create laboratory experiments that will help the industry gain confidence in numerical techniques as well as provide software developers with insights on the strengths and weaknesses of numerical software. In this study, three benchmarks proposed by the FDA are used to compare experimental results with LS-DYNA® ICFD solver with a Finite Element Method (FEM) formulation and Enhanced Particle Finite Element Method (PFEM-2) formulation. In PFEM-2, on top of the finite element mesh, the advection effects are approximated in a Lagrangian way using flow property carrying particles. This means no stabilization is needed for the Galerkin approximation of the advection term in the transport equations. The PFEM-2 enables analyzing a problem with a large time step and is a big advantage in problems with flows at high Reynolds number. The first and second benchmark problems are the flows in a nozzle containing a gradual and a sudden change of diameter and flow in a simplified centrifugal blood pump with the goal of predicting hemolysis. The third benchmark studies the steady flow in a patient-averaged inferior Vena Cava.

• On the prediction of material failure in LS-DYNA®: A comparison between GISSMO and DIEM

  Filipe Andrade, Andre Haufe (DYNAmore GmbH), Markus Feucht (Daimler AG)

  As a consequence of the worldwide tendency in reducing CO2 emissions by producing lighter and more energy-efficient products, the demand for accurate predictions regarding material behavior and material failure has greatly increased in recent years. In particular in the automotive industry, there is also an increasing interest in effectively closing the gap between forming and crash, since the forming operations may highly affect the crashworthiness of the produced parts. In this scenario, a correct depiction of material mechanical degradation and material fracture seems indispensable. Currently, there are several models implemented in LS-DYNA which have been developed to deal with material damage and failure. Many of them are complete constitutive models which consider elasto-plasticity coupled with damage formulations as well as with embedded failure criteria (e.g., *MAT_015, *MAT_052, *MAT_081, *MAT_104, *MAT_120, *MAT_153, among others). Alternatively, LS-DYNA also makes possible the definition of failure and damage through the keyword *MAT_ADD_EROSION, where the user can choose different failure models and fracture criteria which are, in turn, coupled with the selected plasticity model in an ad-hoc fashion. In this context, GISSMO (Generalized Incremental Stress-State dependent Damage Model) and DIEM (Damage Initiation and Evolution Model) are good candidates for the task of predicting ductile failure using LS-DYNA. However, many users still seem to have difficulties in using these models, meanwhile other users, who already master either GISSMO or DIEM, feel somewhat insecure in employing the concurrent model. These difficulties arise mainly because GISSMO and DIEM have been conceived following quite different interpretations of the phenomena that influence failure. For instance, in GISSMO the user has to input a failure curve as a function of the triaxiality (and also of the Lode parameter, in the case of solid elements) where this curve is used for the nonlinear accumulation of damage. This strategy intrinsically takes the strain path change into account, for which a numerical calibration based on experimental data is required. Furthermore, an instability curve may also be defined in GISSMO, where in this case, if instability achieves a critical value, the stresses are assumed to be coupled with damage, leading to a ductile dissipation of energy upon fracture. DIEM, on the other hand, allows the user to define multiple damage initiation indicators which evolve simultaneously. For example, the user can define a normal and a shear failure initiation criterion, the former as a function of triaxiality, the latter depending on the so called shear stress function. Additionally, a forming limit curve (FLC) can also be input in DIEM, where this criterion also evolves along the other two failure initiation criteria. The different damage initiation criteria can then be combined in a global damage evolution rule. Similarly to GISSMO, a certain number of experiments is required in order to properly fit the parameters necessary for DIEM. This contribution is an attempt to compare and better understand the differences between GISSMO and DIEM. In this respect, the main differences between both models and how they are intended to predict failure will be comprehensively discussed. Additionally, the calibration of a dual-phase steel using GISSMO and DIEM will be used to better highlight the differences between the models and how these are reflected in the final parameter fitting.

• On the Prony Relaxation Function

  William W. Feng, John O. Hallquist - Livermore Software Technology Corp.

  For solving viscoelastic problems, the constitutive equations involve convolution integrals with relaxation functions. The relaxation function, G (t ) , is often written in Prony series...

• On the Quasi-Static Perforation Resistance of Circular AA5083-H116 Aluminium Plates

  F. Grytten, T. Børvik, O.S. Hopperstad, M. Langseth - Norwegian University of Science and Technology

  This paper presents numerical simulations of quasi-static perforation of circular AA5083-H116 aluminium plates. The perforation process was analysed with 2D-axisymmetric elements, brick elements and shell elements. Slightly modified versions of the Johnson-Cook constitutive relation and fracture criterion were used in the finite element simulations to model the material behaviour. A factorial design was used to investigate the influence of varying plate thickness, boundary conditions, punch diameter and nose shape. Comparisons between LS-DYNA simulations and experiments were made and good qualitative agreement was in general found. However, some quantitative differences were observed.

• On the Setup and Simulation of Large Scale LEGO Models Build with LS-DYNA and LoCo

  T. Gerlinger, D. Koch, A. Haufe (DYNAmore), N. Karajan (DYNAmore Ohio), M. Thiele, A. Sahurnean (SCALE)

  Playing with LEGO® bricks is something many engineers might have enjoyed during their childhood. Building any kind of mechanical construction allows creativity and complexity to an extent which probably contributed to their fascination and finally to their decision of becoming engineers. It’s interesting to see how many of them are still fascinated by LEGO® even in their adult life. Especially for children, or for those with an active inner child, crashing these models into each other is even more fun, because seeing all those bricks fly all over the place is just fascinating, beyond any scientific or professional aspect.

• One-step Method for Tri-Axial Carbon Fiber Reinforced Composites in LS-DYNA®

  In this work, an algorithm for one-step analysis approach of tri-axial carbon fiber reinforced composites (CFRC) modeling is introduced and successfully implemented in LS-DYNA. Local fiber rotations during the forming process of fiber reinforced composites are almost inevitable. These rotations have significant effect on the material behaviors of the composite, especially for composites with tri-axial carbon fibers embedded in. In the current work, rotation effects of the embedded fibers are considered and new implementation is capable of handling composites with tri-axial carbon fibers. The prediction ability of the algorithm is demonstrated through modeling of a double dome part with tri-axial carbon fiber composites. Good agreement is obtained in the initial composite shape prediction as compared to experimental data.

• OpenForm - A New Intuitive Graphical User Interface for Industrial Forming Simulation

  C. Kaulich, M. Wenzlaff (GNS mbH)

  Since the mid nineties sheet metal forming simulation has been widely used to take the uncertainty out of the die design process. When forming simulation was first introduced into the work of die designers the main focus was on the prediction of thinning, cracking and draw-in of the sheet metal. Later, the prediction of wrinkling, springback and surface defects became challenges finite element forming simulation packages had to cope with. While the prediction of thinning, cracking and material draw-in has now become a relatively easy task for numerical simulation, springback prediction and the detection of surface defects are still great challenges requiring advanced finite element simulation software and considerable expertise and experience in its application. More recently, hot forming simulation has added to the complexity of numerical simulation in the field of sheet metal forming. Since thermodynamical effects also have to be considered in the simulation of hot forming processes, even more experienced users are necessary to ensure that reasonable results are achieved. However, as a rule die designers are not numerical experts, and the use of more advanced finite element software remains a hurdle. Therefore, in the past, forming simulation software packages were assessed not so much by the complexity of their underlying physical models or the integrity of their numerical algorithms as they were for their user-friendliness and the efficiency with which input data could be generated even by inexperienced users. This is particularly reflected by the widespread use of so-called inverse or one step solvers. However, there seems to be a growing awareness among die designers that a rise in the quality of simulation results demands more advanced physical and mathematical models and therefore requires the use of finite element software that is, inevitably, more difficult to handle. As such, in a growing number of companies, more than one software package is used for sheet metal forming simulation. There is forming simulation software that is widely and efficiently deployed for the prediction of thinning and cracking but that fails to deliver good springback results. On the other hand, software that is used for more challenging tasks is often considered inefficient in everyday work. However, the use of different simulation software products increases the costs of numerical forming analysis considerably: not only because of additional licence fees but also because of costly training of staff members or even the engagement of new staff. While OEMs might still be able to cope with the problem of additional costs for software and training, for most of the smaller part suppliers an increase of CAE costs is prohibitive. To overcome this problem GNS has developed a new intuitive graphical user interface for industrial sheet metal forming simulation, called OpenForm. OpenForm is extremely easy to handle and can be used as a pre- and post-processor independently of a particular finite element forming simulation package. The software was designed to enable those who are not finite element experts to carry out multi step forming simulations with even complex multi purpose finite element codes.

• Optimal Forces for the Deceleration of the ES-2 Dummy

  J. Fehr, J. Köhler, C. Kleinbach (University of Stuttgart)

  The purpose of this project is to improve the development process of vehicle safety systems by introducing a new analytic approach. Today, the development of vehicle safety systems, especially the airbag design process, requires many iteration loops via simulations and experiments. In this process, parameters are changed, a new simulation is conducted and the injury values are evaluated. We have a different, two folded approach: First we calculate the optimal forces to decelerate a dummy or human body.

• OPTIMISATION AND ROBUSTNESS OF SIDE AIRBAG DESIGN AND ANALYSIS

  Tayeb Zeguer - Jaguar cars

  In order to yield significant added value, computer model need to reach to a level of reliability that enables decisions, which are only based on simulation results. Airbag deployment is highly non linear and non reproducible. Scatter in all system properties and boundary conditions also cause scatter in the performance of the system. The aim of this paper is to use stochastic simulation approach to include this natural scatter into the computer models. This allows evaluation of the performance scatter and thus an assessment of reliability and quality of the simulated system. Stochastic simulation can be used for system improvement, which offers a further application tool for system optimisation. The problem is not to find optimum solution in a mathematical sense, but to develop sufficiently good and especially robust solutions for real world situations. In this paper stochastic approach will be introduced and applied to the side airbag deployment.

• Optimisation of Fixturing Clamps to Improve Panel Measurement Robustness

  Ben Crone, Arup;, Michael Buckley, aguar Land Rover;, Amelia Agnew, Arup

  Tolerance measurement of sheet metal parts – such as those used in body in white assembly – is a critical task for the automotive industry that can lead to significant financial losses as a result of poor gauge R&R design and data misinterpretation. Current measurement systems use clamps to load panels onto fixtures. However, since non-rigid parts deflect with clamping pressure and under their own self-weight, measurement reproducibility and repeatability are affected by the number, location and sequence of the clamps.

• Optimising Run Times for Sheet Metal Forming Simulation

  Trevor Dutton (Dutton Simulation Ltd), Annika Weinschenk (Hexagon)

  Many practitioners of sheet metal forming simulation work in the lower tiers of the manufacturing sector where they tend to rely on PC technology (such as desktop workstations or laptops) to solve their models. Fast turnaround of analyses is critical to success during the process engineering and tool design stage so optimising the model run time is very important. Most PC hardware now provides multi-core chip technology as standard so this paper examines the differences in run times with different numbers of solver cores across a range of model sizes in order to establish best practice, and indirectly best value for money when investing in both simulation software and hardware. The paper considers a selection of LS-DYNA® SMP and MPP solvers, examining the scalability across different numbers of cores (up to 16 maximum) and the interaction between solver scalability and the use of adaptivity – the differences from running with a fixed, uniform, small element size vs. an initial large element size mesh with varying levels of adaptivity are described. The method of mass scaling (standard vs selective) is also examined, to determine the influence of time step on both run time and results. A number of other factors that can influence run time are also reviewed, including adaptivity parameters such as fusion settings, and the type of storage disk hardware used (HDD vs SSD). A number of recommendations are offered, based on model size and available hardware, in the hope that workers in the field of sheet metal forming will be able to efficiently apply the LS-DYNA solver for this important and widespread application.

• Optimization and robustness of complex material model simulations with modeFRONTIER

  Marco Perillo, Vito Primavera, Luca Fuligno - EnginSoft SpA, Giulia Fabbri, Casper Steenbergen, Nicolò Pasini - Automobili Lamborghini SpA

  Experimental quasi-static and dynamic tests were conducted over different types of advanced material samples, such as composite sandwich, in order to derive both mechanical and numerical input parameters for LS-DYNA material models. The characterization of models addressed to reproduce the behaviour of real materials takes great importance in order to simulate accurately complex phenomena such as crash tests and impact events. This work deals with an innovative procedure aimed to calibrate the constitutive parameters of LS- DYNA advanced material models, and use them for prediction, design optimization and robustness analysis, hence reducing the need of further expensive experimental tests. This kind of approach allows also to understand the influence of physical and geometrical variables on composite dynamic structural response, or to get improved solution for industrial case studies. More in details, the available experimental data were imported in the modeFRONTIER Process Integration and Design Optimization software. An efficient stochastic optimization algorithm performed the calibration of the mechanical and numerical parameters of the existing LS-DYNA models, with a fully automated process. Such models could then be handled by modeFRONTIER to steer LS-DYNA simulation campaigns improving the design of composite and sandwich laminates. Any kind of free parameters to be investigated can be included in such a process, and the constraints to be respected and the multiple objectives to be pursued too. A short description of the most innovative techniques to do that will be given. An experimental-numerical procedure example from Automobili Lamborghini Composite Technical Department is shown.

• Optimization and robustness of complex material model simulations with modeFRONTIER

  Marco Perillo, Vito Primavera, Luca Fuligno - EnginSoft SpA, Giulia Fabbri, Casper Steenbergen, Nicolò Pasini - Automobili Lamborghini SpA

  Experimental quasi-static and dynamic tests were conducted over different types of advanced material samples, such as composite sandwich, in order to derive both mechanical and numerical input parameters for LS-DYNA material models. The characterization of models addressed to reproduce the behaviour of real materials takes great importance in order to simulate accurately complex phenomena such as crash tests and impact events. This work deals with an innovative procedure aimed to calibrate the constitutive parameters of LS- DYNA advanced material models, and use them for prediction, design optimization and robustness analysis, hence reducing the need of further expensive experimental tests. This kind of approach allows also to understand the influence of physical and geometrical variables on composite dynamic structural response, or to get improved solution for industrial case studies. More in details, the available experimental data were imported in the modeFRONTIER Process Integration and Design Optimization software. An efficient stochastic optimization algorithm performed the calibration of the mechanical and numerical parameters of the existing LS-DYNA models, with a fully automated process. Such models could then be handled by modeFRONTIER to steer LS-DYNA simulation campaigns improving the design of composite and sandwich laminates. Any kind of free parameters to be investigated can be included in such a process, and the constraints to be respected and the multiple objectives to be pursued too. A short description of the most innovative techniques to do that will be given. An experimental-numerical procedure example from Automobili Lamborghini Composite Technical Department is shown.

• Optimization and Sensitivity Analysis of Numerical Simulation of Tubular Hydroforming

  Honggang An, Daniel E. Green - University of Windsor, Canada

  Optimization and sensitivity analysis is important although difficult to obtain for tubular hydroforming, because of the implicit relationship between the load path variables (internal pressure and tube end displacement) and the dependent variables (such as stress, strain and final tube thickness). In this paper, the Taguchi method was used in conjunction with virtual hydroforming experiments using LS-DYNA® to carry out the sensitivity analysis and optimization of straight-tube hydroforming. This method employs an orthogonal array to study a large parameter space using only a small number of numerical simulations. Since the tube wall undergoes bending as it fills the corner of the die during the final stage of hydroforming, the strain path becomes non-linear. In this situation, the traditional strain forming limit diagram (FLD) is not a reliable criterion for necking/fracture. In contrast, the forming limit stress diagram (FLSD) is practically strain path-independent. Therefore, the FLSD was adopted for the necking/fracture criterion of the process. Multi-objective functions that consider necking/fracture, wrinkling and severe thinning were taken to evaluate the performance of each simulation. The Pareto optimum was obtained with a minimum failure value using the minimum distance method. Furthermore, the analysis of variance (ANOVA) statistical method was used to determine the effects of the forming parameters on the quality of the final hydroformed part. The factor response was completed using the Signal-to-Noise (S/N) ratio and ANOVA results. The ANOVA indicates the degree of sensitivity for the hydroforming parameters, and expansion pressure, calibration pressure, and tube end displacement were shown to be the three most important factors. This combination of numerical analyses and an optimization technique has helped to define a load path that leads to a robust manufacturing process and good part quality. Keywords: Tube hydroforming, FLSD, Taguchi method, Sensitivity analysis, Pareto optimization

• Optimization Design of Bonnet Inner Based on Pedestrian Head Protection and Stiffness Requirements

  Xiaomin Zeng, Xiongqi Peng (Shanghai Jiao Tong University), Hongsheng Lu (Shanghai Hengstar Technology Co. Ltd), Edmondo Di Pasquale (SimTech Simulation et Technologie)

  Pedestrian head impact with bonnet is one of the major causes for pedestrian severe injury or fatality. This paper proposes a multidisciplinary design optimization method for bonnet inner based on pedestrian head protection along with stiffness requirements. The static stiffness and headform collision procedure with regard to a particular industrial bonnet are analyzed. Parametric design and optimization analysis of this bonnet are carried out. Optimization solution significantly achieves better head protection effect under the premise of meeting the stiffness requirements, which validates the feasibility of this multidisciplinary optimization method and provides an approach for the optimal design of engine bonnet inner. This work shows the importance of a simultaneous approach of different disciplines in bonnet design.

• Optimization of a Cockpit Structure according to ECE-R21 Regulation

  Michael Walter, Hartmut Chladek, Dr. Armin Huß - Ingenieurbüro Huß und Feickert, Germany

  For a prototype of the new LANDROVER cockpit, developed by Siemens VDO Automotive, the design of the co-driver airbag area had to be optimized with the help of simulation in order to fulfill the guidelines of ECE-R 21. Furthermore a more limited inhouse-target had to be reached. The actual state of the prototype was illustrated by simulation and the influence of different measures on the crash behavior was examined. Among other things the following modifications were accomplished: • Changing the stiffness of the instrument panel by specific design of the rib structure • Reducing the stiffness of the airbag box and its connections • Partial absorption of the impact energy using foam depositors between instrument panel and airbag unit The influence of different strategic ways to optimize the crash behavior, in respect of head impact will be shown on a simplified cockpit model. Finally, a comparison of the simulation and the testing of the new RANGE ROVER cockpit will be given.

• Optimization of a Lower Bumper Support regarding Pedestrian Protection Requirements using ANSA and LS-OPT

  I. Wetzstein, B. Lauterbach, N. Erzgräber, L. Harzheim (Adam Opel)

  A variety of pedestrian protection requirements must be considered during the vehicle development process, in order to improve the protection of vulnerable road users. The lower bumper support, which is located at the vehicle front (s. Fig. 1), is designed to generate beneficial leg kinematics from early in the impact.

• Optimization of an Adaptive Restraint System Using LS-OPT and Visual Exploration of the Design Space Using D-SPEX

  Marko Thiele, Heiner Mullerschön - DYNAmore GmbH, Marcel van den Hove and Bernd Mlekusch - AUDI AG

  The purpose of this paper is to explore some interesting aspects of optimization for crashworthiness occupant safety applications and to propose optimization strategies for highly nonlinear problems. With the today’s state of technology i t is possible to identify specific load cases and different types of occupants i n the car. System parameters of the restraint system, such as trigger time for seat- belt, airbag and steering column can be adapted to particular load cases. This is referred to an adaptive restraint system. I n the first part of the paper different optimization strategies are discussed and pros and cons are compared. I n addition, a methodology to get a reliable surrogate model using neural networks is introduced. The surrogate model (Meta-Model or Response Surface Model) approximates the relationship between design parameters and a physical response and can be used to visualize and explore the design space. I n the second part the application of the Successive Response Surface Scheme (SRSM) for the optimization of an adaptive restraint system is conducted. For this, several front crash load cases are considered. This is performed using LS- OPT (Stander et al. [11]) as optimization software and PAM-Crash as solver for the finite element occupant safety simulations. The procedure of generating an advanced meta-model to get an approximation of the global design space using neural networks is demonstrated for this example. Furthermore, the visualization of multi-dimensional meta-models i n two- and three-dimensional design space is illustrated by using the matlab application D-SPEX. The program D-SPEX interfaces with LS-OPT as an advanced optimization and stochastic post-processor.

• OPTIMIZATION OF DESIGN PARAMETERS FOR A CONTACT SENSOR IN BUMPER-PEDESTRIAN IMPACT BY USING FE MODELS

  Sunan HUANG, Jikuang YANG - Chalmers University of Technology, Sweden, Rikard FREDRIKSSON, Autoliv Research, Autoliv AB, Sweden

  An active hood system was developed in Autoliv to minimize the head injury risk of pedestrians from impacts with car front. In order to detect the car-to-pedestrian impact in time, a contact sensor placed in the car bumper is needed. The stiffness of the bumper foam material is highly dependent on the environment temperature, which will result in unstable output from the contact sensor. A new pedestrian-bumper contact sensor was developed in Autoliv, in order to receive a stable output from the sensor at different temperatures. In this study, the new contact sensor was analyzed and evaluated by using a bumper FE model of a production car. A baseline bumper FE model was firstly developed and validated by using EuroNCAP lower legform impact tests on the production car bumper. In order to improve the safety performance of the bumper FE model, the bumper foam material was softened and the foam thickness was increased. At the same time, the location, boundary condition and material property of the lower stiffener was also adjusted. As a result, the improved bumper model can meet the acceptance requirements of the EEVC WG17 lower legform impact test. A human lower extremity FE model was developed and the safety performance of the improved bumper was further evaluated by using the human lower extremity FE model.

• Optimization of Nonlinear Dynamical Problems Using Successive Linear Approximations in LS-OPT

  Nielen Stander - Livermore Software Technology Corporation,Livermore, CA, Rudolf Reichert, Thomas Frank - DaimlerChrysler, Stuttgart, Germany

  This paper focuses on a successive response surface method for the optimiza- tion of problems in nonlinear dynamics. The response surfaces are built using linear mid-range approximations. To assure convergence, the method employs two dynamic parameters to adjust the move limits. These are determined by the proximity of successive optimal points and the degree of oscillation, respective- ly. Three diverse examples namely in impact design, sheet metal process design and system identification are used to demonstrate the method. The methodolo- gy has been incorporated as a parallel solver in the commercial software code LS-OPT.

• OPTIMIZATION OF STIFFENED LAMINATED COMPOSITE CYLINDRICAL PANELS IN THE BUCKLING AND POSTBUCKLING ANALYSIS.

  A. Korjakin, A.Ivahskov, A. Kovalev

  Stiffened plates and curved panels are widely used as primary structural elements in aerospace, marine and civil engineering. Their stable postbuckling behavior and their capability to sustain loads far in excess of their initial buckling loads may lead to considerable weight savings, if their postbuckling strength is fully utilized and possible fatigue problems are eliminated. In the presence of large deflections, bifurcations, load and displacement limit points, the analysis of arbitrary anisotropic shells requires the adoption of incremental and iterative procedures capable of tracing the complete load- displacement path. Although the true response is dynamic in nature, a fully static solution is followed in most cases. Stiffened panels loaded in axial compression were extensively studied and employed in aeronautical structures in the thirties, forties and beyond, yielding the effective width. In the last decades, the trend to optimize the design shear panels, and the employment of composites and higher strength metals, has led to similar required relative stiffnesses in both civil and aeronautical engineering. The civil engineers employ stiffer flanges in order to improve the postbuckling strength of the web and the aeronautical engineers decrease the relative flange cross-sectional area in order to save weight. The nonlinear analysis of shells requires the efficient blend of finite element technology and path-following techniques. Due to the increased computational effort of the incremental and iterative solution process, it is imperative to obtain the structural response by simple, inexpensive and accurate finite elements. In this paper the postbuckling performance of composite shells using computer code LS-DYNA is analysed.

• Optimization of the Blank Holder Stiffness in Deep Drawing Processes by using FEA

  R. Radonjic, Prof. M. Liewald, F. Han (University of Stuttgart)

  When deep drawing the parts with complex geometry, changeable thickening can occur in the flange area. Extreme thickening of the part flange will cause pressure peaks at the contact surface between blank holder and part. This undesired occurrence during deep drawing will reduce process window and process robustness as well. In this paper, an approach to optimize the blank holder stiffness in deep drawing process is presented.

• Optimization of Turbine Blade Fir Tree Root Geometry Utilizing LS-PrePost in Pre- and Postprocessing

  J. Jankovec (Research and Testing Institute Plzen)

  This paper describes geometry parameterization of turbine blade fir tree root prepared in LS-Prepost. The generated FE model utilizes LS-OPT in optimization loop. Simulation results of LS-DYNA implicit solver were used to extract required responses. Some problems arising during solving the task will be discussed in the article.

• Optimization study of a parametric vehicle bumper subsystem under multiple load cases using LMS Virtual.Lab and OPTIMUS

  Laszlo Farkas, Cédric Canadas, Stijn Donders, Tom Van Langenhove, Nick Tzannetakis - LMS International, Johan Tielens, Danny Schildermans - PUNCH Metals N.V.

  This paper deals with the design and optimization of a vehicle bumper subsystem, which is a key scenario for vehicle component design. More than ever before, the automotive industry operates in a highly competitive environment. Manufacturers must deal with competitive pressure and with conflicting demands from customers and regulatory bodies regarding the vehicle functional performance and the environmental and societal impact, which forces them to develop products of increasing quality in even shorter time. As a result, bumper suppliers are under pressure to increasingly limit the weight, while meeting all relevant design targets for crashworthiness and safety. LMS Virtual.Lab offers an integrated platform to design engineers who are challenged with multi-attribute design of mechanical structures. For the vehicle bumper subsystem of interest, engineers can start from the CAD design, define a generic assembly model, define multi-attribute simulation models and meshes, as well as multiple analysis cases. The entire process is fully associative, enabling automated iteration of design and model changes, which is key towards an efficient optimization process with OPTIMUS. The structural bumper model is created, parameterizing its geometric and sectional properties. A Design of Experiments (DOE) strategy is adopted to efficiently identify the most important design parameters. Subsequently, an optimization is performed on small-sized Response Surface Models (RSM), in order to minimize the vehicle bumper weight, while meeting all design targets.

• Optimization study of a parametric vehicle bumper subsystem under multiple load cases using LMS Virtual.Lab and OPTIMUS

  Laszlo Farkas, Cédric Canadas, Stijn Donders, Tom Van Langenhove, Nick Tzannetakis - LMS International, Johan Tielens, Danny Schildermans - PUNCH Metals N.V.

  This paper deals with the design and optimization of a vehicle bumper subsystem, which is a key scenario for vehicle component design. More than ever before, the automotive industry operates in a highly competitive environment. Manufacturers must deal with competitive pressure and with conflicting demands from customers and regulatory bodies regarding the vehicle functional performance and the environmental and societal impact, which forces them to develop products of increasing quality in even shorter time. As a result, bumper suppliers are under pressure to increasingly limit the weight, while meeting all relevant design targets for crashworthiness and safety. LMS Virtual.Lab offers an integrated platform to design engineers who are challenged with multi-attribute design of mechanical structures. For the vehicle bumper subsystem of interest, engineers can start from the CAD design, define a generic assembly model, define multi-attribute simulation models and meshes, as well as multiple analysis cases. The entire process is fully associative, enabling automated iteration of design and model changes, which is key towards an efficient optimization process with OPTIMUS. The structural bumper model is created, parameterizing its geometric and sectional properties. A Design of Experiments (DOE) strategy is adopted to efficiently identify the most important design parameters. Subsequently, an optimization is performed on small-sized Response Surface Models (RSM), in order to minimize the vehicle bumper weight, while meeting all design targets.

• Optimization Techniques in Conjunction with Complex ATD FE Models Using LS-DYNA

  John Cooper, Dr. Hyunsok Pang, Matthew McCann, Dr. Ron Averill - Denton ATD, Inc and Red Cedar Technologies, Inc

  This paper discusses the optimization methods used by Denton to create FE ATD models. Anthropomorphic Test Devices (ATDs also known as Dummies) are manufactured with a variety of hyperelastic and viscoelastic materials. The production processes used to manufacture ATD’s result in variations between dummies that can have a significant influence on dummy performance. In addition the load cases present during testing with ATDs are very complex and of short time duration. A typical frontal crash test may last 100ms but the load cycle on an ATD body region may last only 10ms. The end result is a complex series of issues that can be very difficult to solve in an FE model, using conventional techniques. The number of potential variables (sample list) associated with a specific performance metric (time history, acceleration, etc) can be very large. The settings for a given variable and the effect of that variable setting are difficult to determine given the complexity and short duration of the simulated event. In particular, the use of the hybrid adaptive SHERPA algorithm in the HEEDS software in conjunction with LS-DYNA for determining parameter values is discussed.

• Optimizing LS-DYNA® Productivity in Cluster Environments

  Gilad Shainer, Swati Kher - Mellanox Technologies

  Increasing demand for computing power in scientific and engineering applications has spurred deployment of high- performance computing (HPC) clusters. Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) are computational technologies that can take advantage of HPC clusters for increasing engineering design productivity, reduce development cost and faster time to market. The end-user benefits are far more sophisticated, enhanced, safer and robust products. With increase usage of multi-core in HPC clusters, FEA and CFD applications need to be highly parallel and scalable in order to fully utilize cluster computing ability. Moreover, multi-core based clusters impose higher demands on cluster components, in particular cluster interconnect. In this paper we investigate the optimum usage of high-performance clusters for maximum efficiency and productivity, for CAE applications, and for automotive design in particular.

• Optimizing the Biofidelity of the Warrior Injury Assessment Manikin through Design of Experiments

  M.P. Boyle, A.M. Lennon, N.A. Vavalle, M.T. Shanaman, C.W. Lomicka, C.O. Pyles, R.S. Armiger, The Johns Hopkins University Applied Physics Laboratory;, J.P. Schap, A.M. Baker, F.S. Gayzik, Wake Forest University Center for Injury Biomechanics;, M.R. Chowdhury, Army Research Laboratory, Adelphi

  With improvised explosive devices beneath military vehicles causing an increasing number of casualties amongst warfighters, the United States Army requires a method by which to evaluate injury mitigation technologies in vehicles, including seat designs and other safety systems. In response to complications associated with the use of Post Mortem Human Subjects (PMHS), the United States Army Research Laboratory initiated an endeavor to develop a biofidelic Anthropomorphic Test Device (ATD), to serve as a surrogate for injury prediction in underbody blast (UBB) tests with military vehicles. Accurately predicting injuries, with the aptly named Warrior Injury Assessment Manikin (WIAMan), began with the development of an ATD with high biofidelity, or specifically, the ability to reproduce the response of the human body to an UBB event.

• Optimizing Thermoplastic Parts in Crash Applications - Status and Vision

  Andreas Wüst, Dr. Stefan Glaser – BASF SE, Dr. Steffen Frik - Opel AG

• Optimum Design of a Cellular Phone Using LS-OPT Considering the Phone Drop Tes

  Jung Woo Kim - R & D Center, In-Yong Jo, Young-Gu Chung, Jae Moon Lim - KOSTECH Inc.

  The main factor of the cellular phone fracture is the impact due to the phone drop. Two cases of design criteria are assigned to reduce the damage of the phone for the drop test. One is that the main part and the battery should not be separated, being dropped at a height of 30 cm. The other is that they should be separated, being dropped at a height of 150 cm. The separation between them could reduce the damage of the cellular phone. However, it is undesirable for the battery to be frequently separated from the phone at a low height. The purpose of this study is to optimize the locking knob of the cellular phone considering the phone drop test at a height of 30cm. The design variables are the width and the thickness of the locking knob. LS-INGRID is adapted to automate the optimum design process because the shape of the locking knob could be changed in the design process. The optimum design is performed using RSM (response surface method) in the LS-OPT. The optimum design values are determined to optimize the displacement at the certain position of the locking knob of the cellular phone.

• Optimum Design of a Steel Bar Breaking System in a Sled Test Facility Using LS-OPT

  In-Yong Jo, Young-Gu Chung, Hyung-Joo Lee, Jae Moon Lim - CAE Team, KOSTECH Inc.

  The steel bar breaking system is a component of sled test system for the automobile crashworthiness. The purpose of this study is to optimize the steel bar breaking system in order to extract the crash pulse close to the barrier test result. The design variables are the height, the thickness and the number of each array of the steel bar plates. The optimum design is obtained using DOE (design of experiments) and RSM (response surface method) in the LS-OPT. LS-INGRID is adapted to automate the optimization process because the dimensions of the steel bar plates could be changed in the design process. The optimum design values of the steel bar breaking system are determined to minimize the difference between the crash pulses of the test result and the simulation result.

• Optional Strain-Rate Forms for the Johnson Cook Constitutive Model and the Role of the Parameter Epsilon_0

  Len Schwer - Schwer Engineering and Consulting Services

  A brief review of the standard Johnson-Cook model is presented. Three optional strainrate forms are introduced and calibrated to laboratory data for A36 steel. Next a brief description of the LS-DYNA Version 971 implementation of the new strain-rate forms, within the existing viscoplastic formulation of the Johnson-Cook model, is presented. Finally, all four calibrated strain-rate forms are exercised in single element uniaxial stress test simulations, and the results are compared with the A36 steel effective stress versus effective strain data at three different strain rates. The comparison of the calibrated model response to the quasi-static A36 steel data is used to illustrate the role & of the Johnson-Cook parameter ε 0 .

• Orbital Forming of SKF's Hub Bearing Units

  E. Omerspahic; J. Facht (SKF)

  Orbital forming is an incremental cold forming process that can be used to shape materials such as metals with much lower forming loads compared to pressing. The orbiting tool rotates at a fixed angle to the machine axis and applies both pressure and orbital motion to progressively shaped material. Because the tool is nutating and not rotating, minimal friction is obtained between the workpiece and tool. In SKF, orbital forming is used by SKF to close automotive hub bearing units (wheel bearings) where a nose is shaped over a ring. This process has been modelled and simulated in LS-DYNA. The model is a mock-up model where rollers and the outer ring are not included. Extensive experimental work has been done to make foundation for the modelling: • In calibration phase, the FE model has been optimized against experiments to obtain the set of material and process parameters. • In validation phase, the FE model has been evaluated against several experiments where geometries and process parameters have been varied to confirm the set up from the calibration phase. The FE modelling consists of three interdependent simulations: Assembling simulation of inserting the SIR on the FIR, orbital forming simulation with the forming tool and springback simulation describing the relaxation process after forming. A good agreement between simulated and experimental results is obtained, and the FE model can be used for design of the orbital manufacturing processes.

• Orion space craft water and land landing system simulation; An injury case study

  Ala Tabiei - The University of Cincinnati, Chuck Lawrence - NASA Glenn Research Center

  NASA’s return to moon program had kept the NESC (NASA Engineering and Safety Center) busy for the past several years. The NESC was charged to come up with a safe landing for the Orion capsule. Water and land landing is considered for the Orion capsule. The NESC took major initiative to come up with recommendation to the program. Part of this initiative is to come up with Injury criteria recommendation during the landing of the Orion capsule. Impact simulation is used to assess the injury and pulse responses of the Orion during landing. Major tasks were under taken to validate the steps of the impact simulations. The models used in water landing, soil landing, and the finite element dummies were validated through experimental testing. In here some of the validation is presented. The paper finally compares the injury values of the astronauts during water and land landing.

• Overview of LS-TaSCTM and New Feature Highlights

  Guilian Yi, Imtiaz Gandikota

  The general capabilities of LS-TaSC were designed to solve topology and shape optimization of large nonlinear problems involving dynamic loads and contact conditions applied to solid and shell structures. LS-TaSC can deal with huge models with up to 10 million elements, multiple load cases, and multiple disciplines. Three main categories of structural optimization problems can be addressed by LS-TaSC, including topology optimization, topometry optimization, and shape optimization. Topology optimization uses the relative densities of elements as design variables, minimizes the structural mass or a response, or maintain a target mass fraction at the global level, and maximizes the structural stiffness or the fundamental frequency at the local level. Topometry optimization uses the shell element thicknesses as the design variables, and it has similar setting options in terms of the definition of the objective function. Shape optimization chooses a free shape of the outer surface contour to design and finds the best surface shape that yields a uniform stress on the surface. The von Mises stress field is designed, and the uniform surface stress reduces the occurrences of stress concentration.

• Overview of LSTC’s LS-DYNA Anthropomorphic Models

  Christoph Maurath, Sarba Guha, Dilip Bhalsod, Mike Burger, Jacob Krebs, Suri Bala - LSTC, Sebastian Stahlschmidt, Reuben D'Souza - DYNAmore GmbH, Pradeep Mohan, Dhafer Marzougui - The George Washington University

  The paper gives an overview of LSTC's LS-DYNA crash test dummy model development effort. The model development process is outlined. Details of all released models are presented. The development status of models currently under development is addressed. Outlook to future models is given.

• Overview of pedestrian analysis setup and post-processing using the Oasys LS-DYNA Environment with a focus on new features

  G. Newlands, B. Crone (Arup)

  The Oasys LS-DYNA Environment provides a comprehensive solution across the whole LS-DYNA workflow. One aspect of that workflow in automotive engineering is pedestrian protection. Pedestrian protection is important to the design and development of the front end of vehicles. The various protocols, impactors and methods relating to pedestrian protection mean that the CAE process can be complex and time consuming. The Oasys tools aid in this process. These tools are available for both head and leg impact analyses and have been used successfully on past and current vehicle design projects within Arup and in OEM’s to accelerate the workflow. This paper gives an overview of the tools, with a focus on the latest features introduced to the recent releases of the Oasys LS-DYNA Environment – The HIC Area Calculator and the Pedestrian Run Builder.

• Overview of the CESE Compressible Fluid and FSI Solvers

  Zeng-chan Zhang, Grant Cook, Jr., Kyoung-su Im (Livermore Software Technology, an ANSYS Company)

  The Original CESE solver in LS-DYNA® is a compressible fluid solver. Over time, more and more capabilities and applications have been added, especially coupled with the LS-DYNA structural FEM solver to solve different fluid/structure interaction (FSI) problems. Among the many problem types suited to using the CESE solver are the following applications: flimsy vacuum sucking in tissue processing, airbag deployment, blast wave FSI, cavitation in fuel injection, etc. In this paper, there are three parts: (i) a brief review of the current CESE solver; (ii) introduction of our new dual CESE solver; (iii) our two different FSI solvers and their applications.

• PAB Deployment Simulation with Curved Retainer

  Linhuo Shi - TG North America Corporation

  Some passenger side airbags (PAB) are mounted on the cylindrical inflator directly through retainer with similar curvature of the inflator. To accurately simulate the deployment of such a PAB, a fine-tuned model using additional constraints in LS-DYNA are employed in this paper to simulate the curved mounted PAB. The results from the fine-tuned model are compared with the simulation results from the PAB models with simply fixed bag mouth. It is found that by approximating the curved mounting with simply fixed airbag mouth introduces negligible error in airbag deployment simulation.

• Parachute Deployment Simulations using LS-DYNA ICFD Solver and Strong FSI Coupling

  M. Le Garrec, A. Poncet, V. Lapoujade (DynaS+)

  The main goal of military airdrops is the accurate delivery of cargo released from a moving air vehicle via parachute. The airdrop trajectory results from the movement of the dropped package and the dynamics of the parachutes deployment (Fig.1:). After having treated the freefall of a rigid object in the near flow of an airplane ([8]), the present paper focuses on the parachute deployment modelling and its challenges in LS-DYNA.

• PARALLEL ENGINEERING SIMULATIONS BASED ON FORMING SIMULATION OF A HEAT EXCHANGER PLATE

  Gabrielson P. - Alfa Laval Lund AB, Thuvesen D. - The Swedish Institute of Production Engineering Research

  Normally, simulation regarding computational fluid dynamics (CDF), structural mechanics and heat transfer simulations in sheet metal applications are made without a forming simulated part. Instead the simulation is based on especially constructed parts, with some kind of nominal geometry, only for the specific simulation. This paper presents the use of sheet metal forming simulation of an advanced thin sheet metal part as input to other simulations. Here forming simulation provides input data for different parallel simulations: simulation of computational fluid dynamics (CFD), simulation of structural mechanics and thermal heat transfer simulations. From the forming simulation output e.g. pressed part geometry, it should be possible to use sheet metal thinning, residual stress and strain as input in other simulations later on. However, today it is not trivial to export and use the result from LS-DYNA to the desired application. We have developed a method for carrying a correct geometry into parallel simulations with input from forming simulated section. A special heat exchanger plate, with intensive and sharp patterns, was developed to study the influence of variations in geometry of the pressing tool. The sheet metal forming simulation was performed with LS-DYNA. A C++ program was developed to calculate new nodes in the surface of forming simulated section. This to be able to created a geometrically correct solid model as input in parallel simulations. A simulation of computational fluid dynamics was performed with forming simulated section of a heat exchanger plate as input to verify method. Result achieved from forming simulation regarding thickness variation and material inflow were compared with real pressing results for stainless steel material. The comparison showed good agreement between the simulations and the measured parameters on a processed heat exchange plate. Previously the design engineer could actually make real test tools and press metal sheets in the workshop. This is very expensive and even more important; it takes a lot of time. Here the forming simulation is a very powerful tool. Geometrically correct model achieved with described method and forming simulation is possible to use as input in simulation of computational fluid dynamics (CFD). In a similar manner the simulation of structural mechanics and thermal heat transfer are possible to perform with thickness variations instead of nominal geometry. The sheet metal simulation is nowadays used for a number of different purposes. The main purpose is to detect problems with the tools. The second aspect is to be able to make other useful simulations with the geometry of the simulated heat exchanger plate and it is necessary to be well established in this IT-area to be a competitive manufacturer of heat exchanger plates in future.

• PARALLEL PERFORMANCE OF LS-DYNA ON THE NEXT GENERATION OF COMPUTER SYSTEMS

  Jeff Zais - IBM

  LS-DYNA is available on a wide variety of computer platforms, ranging from commonplace personal computers to sophisticated vector processors to high-performance scalable servers. This presentation will review historical LS-DYNA performance and look forward to what can be expected in the next generation of computer platforms. The capability of available computer platforms always has a bearing on what type of simulations LS-DYNA end users can run. In the past, departmental machines such as DEC VAX servers provided many computing cycles to users. Porting of the code to Cray vector machines made overnight full-car crash simulations practical. Models grew larger but could still be run overnight as machine speeds increased and SMP parallel versions became available. At the same time, UNIX workstations increased in capability to the point where many sophisticated simulations could be run on desktop machines. Most recently, significant advances in LS-DYNA and computer hardware have taken place in two different areas: scalable servers, and machines based on low-cost processors. The advances are being driven by the growing acceptance of the MPI version of LS-DYNA, the level of performance available from low-cost commodity processors, and the level of performance available from high-performance processors available in scalable systems. Current performance examples and trends in microprocessor improvement can be used to give users guidance on what levels of LS-DYNA performance will be attainable in the next few years.

• Parameter and Optimization Studies for Crashworthiness Design using LS-DYNA and the Altair StudyWizard

  U. Schramm, H. Thomas, K. Hayes - Altair Engineering Inc., Troy, MI

  In the automotive industry the crashworthiness of a design is of special interest. Non-linear finite element analysis, such as in LS-DYNA, is applied to predict the structural responses. Conclusions from these computations can lead to significant design modifications. Usually, intuition leads the iterative process of finding the best design. It is often hard to determine these design modification from the analysis results. In some cases many variations are tried before a satisfactory design is found [1]. Structural optimization and Design of Experiments Studies based on computational methods are useful tools to support the process of finding the right design. The complexity of the layout can be described mathematically as an optimization problem. Using the results of a computational optimization, the decision process can be improved. Optimization of structural elements can lead to significant cost reductions within the design process itself, or with regard to the final design. Industrial application of structural optimization depends on the availability of software products. For linear statics and dynamics such software is available and fairly well supported. Layout and shape optimization can be performed to design structural parts. In design considering crashworthiness no algorithms are available to perform sensitivity analysis and optimization as known in linear statics. An alternative approach is to use response surface methods in conjunction with such a code. Also, DOE approaches can be used.

• Parameter Identification for Forming Simulations of High-Strength Steels

  M. Thomisch, Prof. M. Kley (University Aalen)

  Im Rahmen eines Forschungsvorhabens an der Hochschule für Technik und Wirtschaft in Aalen wird das plastische Umformverhalten von hochfesten Stählen, insbesondere Federstählen, untersucht. Im Detail stehen neben der klassischen Kenngrößen wie Fließgrenze und plastischer Verformung die Ver- und Entfestigungseffekte im Vordergrund der Betrachtung. Bei wechselnder Belastung im plastischen Bereich ist speziell bei hochfesten Stählen der Bauschingereffekt zu beobachten. Dieser lässt sich wie folgt charakterisieren.

• Parameter identification for the simulation of debonding in honeycomb sandwich using LS-Dyna

  M Hörmann - CADFEM GmbH

• Parameter Identification of Coating Parameters to Improve Webbing Bending Response in Passive Safety Crash Simulations

  Seat belt is one of the main load bearing parts for restraining an occupant in a vehicle crash. Thus, accurate modelling of seat belt is important to achieve realistic interaction between belt to Anthropometric Test Devices dummy model in passive safety crash simulation. The belt modelling in the lap area is even more challenging because it also bears out-of-plane load during interaction with the pelvis, causing bending in webbing. Inadequate modelling of the bending response often results in rope-like effect in the lap belt during passive safety crash simulations, causing loss of contact area and eventually incorrect pelvis coupling. Such a behavior of belt is often observed with the application of THOR dummy in crash simulations, leading to an argument that simulations are not able to correctly predict submarining (slippage of belt over the pelvis to load the abdomen) and eventually incorrect estimation of the pelvis iliac forces and moments on the dummy [2]. Therefore, concerns are growing for improving the belt modelling. Besides other modelling aspects (e.g., mesh size, contact modelling, directional dependency of friction etc.), it is believed that including appropriate bending stiffness could improve dummy-to-belt interaction. There are several options available in LS-DYNA to model bending in webbing but the inevitable use of 2D slipring for its robustness and efficiency in the system models poses limitations.

• Parameters Identification for Wood Material (*MAT_143) and its Application on the Modeling of a Typical Timber Nuki Joint

  Benshun Shao, Aliz Fischer, Yuli Huang, Francois Lancelot (ARUP), Nicolette Lewis (University of Washington)

  Understanding the mechanical properties of the timber joint is a crucial aspect of modern wood construction. Numerical simulation of timber joints can provide valuable insights. However, due to the anisotropic nature of the wood, the sensitivity to local sliding and contact effects, the stiffness and strength modelling of timber joint connections is complex. This study explores the capability of the wood material formulation (*MAT_143/*MAT_WOOD) in LS-DYNA® for simulating the bending behavior of a typical Japanese carpentry connection, the Nuki joint. The material parameters identification was first conducted based on various experimental data. To provide robust results in an efficient manner, the usage of LS-OPT® was explored in this process. A 3-D Nuki joint model was then constructed and its bending behavior was compared with the experimental measurements. Sensitivity studies were conducted on the key contact modeling parameters in LS-DYNA. The study describes an efficient workflow for calibrating the wood material parameters. It also discusses the challenges involved in the modeling of timber joinery mechanics in LS-DYNA and offers suggestions for future research on this topic.

• Parametric and Convergence Studies of the Smoothed Particle Galerkin (SPG) Method in Semi-brittle and Ductile Material Failure Analyses

  Youcai Wu, C.T. Wu, Wei Hu, Livermore Software Technology Corporation

  This work presents the state-of-the-art status of the Smoothed Particle Galerkin (SPG) method [1, 2] in LS-DYNA®. The SPG method is a new generation meshfree method developed for modeling the semi-brittle and ductile material failure [3-5]. Different from the conventional finite element method (FEM) where the element erosion technique is utilized to mimic the material separation, the SPG method introduces a bond-based material failure criterion to reproduce the strong discontinuity in displacement field without sacrificing the conservation properties of the system equations. The mathematical and numerical analyses have suggested that the SPG scheme is stable and convergent in modeling material failure processes.

• PARAMETRIC FINITE ELEMENT MODEL OF A SPORTS UTILITY VEHICLE - DEVELOPMENT AND VALIDATION

  Gustavo A. Aramayo - Computation Materials Science Group, Matthew H. Koebbe - XYZ Scientific Applications, Inc.

  As part of the NCAP (New Car Assessment Program) a finite element model of a Ford Explorer SUV has been developed using a formulation that results in a model with arbitrary element size and element size distribution. This correct Abstract. model enables the developer and analyst to choose a finite element model most applicable to the specific crash scenario under study. The element size and element distribution are parametrically defined at the time of the model generation. The general model is verified against several specific models with different element size densities and distribution, and compared with experimental results of crash tests. In the analytical study, models are generated for several crash scenarios and for several degrees of vehicle engagement with the stationary obstacle.

• Parametric Modelling of Simplified Car Models for Assessment of Frontal Impact Compatibility

  Mathias Stein, Darius Friedemann, Alexander Eisenach, Heiko Johannsen - Technische Universität Berlin, Hans Zimmer - SFE GmbH

  The aim of the FIMCAR project (co-funded by the European Commission within the 7th Framework Programme) is to develop and validate a frontal impact assessment approach that considers self and partner protection. In order to assess the influence of different test procedures and metrics on car- to-car compatibility a huge simulation programme is envisaged. However, car-to-car simulations with models of different car manufacturers are almost impossible because of confidentiality. In addition the detailed models of the car manufacturers are complicated to optimise for different assessment procedures and are consuming considerable computational efforts. In order to overcome these problems, parametric car models were built allowing fast modifications. By simplifying the models, computational efforts are reduced. Due to the rapid increase of the calculation power the level of detail in car models has reached a very high level. At the same time the number of discretised parts drops and smaller structures are considered in the meshing process. However, only a few structures are mainly responsible for the frontal crash behaviour of the vehicle. A high variability of mounting positions, connections and stiffness of parts of a car’s front–end offers a big potential in investigations of frontal impact vehicle structures. However, the modification of these criteria is time consuming, especially the modification of a given FE-mesh or geometry model. The software SFE CONCEPTTM offers the possibility to establish an implicit parametric car model in an easy and fast way. A variable geometric model is created by the specification of base lines and cross sections for the different parts. The modification of a structure with respect to connected parts is one of the advantages of SFE CONCEPTTM. Through manipulation of the implicit parameters, new structure concepts and /or small variations of a part’s dimensions can be established. After all the software is able to mesh the geometry and export the data for different solvers like LS-Dyna. In that way it is possible to generate a manifold number of structures, in a fast and certain way which is necessary for the investigations of the influence of these structures in frontal impact compatibility. The set up of the FE model is adapted to the export data structure of SFE CONCEPTTM. This way the models can be simulated directly after modification without further post-editing.

• Parametric optimization of cellular materials through LS-OPT

  Alessandro Giustina, Ivan Colamartino, Paolo Franzosi, Marco Anghileri, Marco Virginio Boniardi

  Cellular materials, characterized by a repetitive pattern of unit cells, feature many advantages with respect to conventional monolithic materials, that make them especially desirable for structural and energy absorption applications. First of all, the intrinsic cellular architecture, characterized usually by an interconnected network of solid struts and sheets results in a lightweight material [1], which at the same time is able also to dissipate large amounts of energy through the deformation of plastic hinges and local buckling phenomena [2], achieving a superior structural efficiency. Moreover, some recently developed geometries allowed to achieve highly desirable and unprecedented structural properties, such as negative Poisson’s ratio, bistability, or recoverable deformation.

• Parametric Projection-based Model Order Reduction For Crash

  Mathias Lesjak, Fabian Duddeck

  Modern passive safety development is associated with numerous simulations and hardware tests. In virtual development, multi-query analysis such as optimization, sensitivity analysis and robustness studies are performed. These methods require many simulation evaluations, which can make their application impractical for large simulation models. An approach to make the development process more efficient is Model Order Reduction (MOR) which uses already generated simulation data to build a Reduced-Order Model (ROM) and accelerate future simulations.

• Parametric ROM Technology for Fast Optimization of Crash Problems

  Radha Krishnan, Sridhar Bijjala, Rajasekaran Mohan

  The purpose of the Crashworthiness analysis is to assess how well a vehicle's structure can protect its occupants during a collision. This study involves transforming the vehicle Crash Model Partially into a Lumped Parameter representation using DEP MeshWorks’ - Reduced Order Modelling (ROM) technology. The ROM model shows an impressive 85-95% correlation with the original Detailed Finite Element model. The complex process of converting the Detailed Finite element model into lumped parameter representation is automated through the ROM approach. The ROM model is further parametrized with a broad ranging category of parameters involving a) shape, b) gage, c) material, d) spot welds, e) adhesives, f) seam welds, g) crush-initiators, h) reinforcements, i) darts, j) bulk-heads, k) slots/holes, l) laser welded blanking, m) ribbing and o) composite lay-up to convert it to an intelligent ‘Parametric ROM Dyna model’ using DEP MeshWorks. This parametric ROM model is integrated with a DOE (Design of Experiments) based Optimization scheme to obtain an optimized design that maximizes Crashworthiness performance and minimizes weight & hence cost. Thanks to the significantly reduced number of nodes/elements in the parametric ROM model, the entire optimization process can be completed in less than 50% of the time that detailed models would require.

• Parametric Study for Evaluating Damageability of Automotive Radiator by Impacting Stones

  S. Singh, M. Usman, J. Raver (Ford Motor Company)

  The performance of automotive engines depends on the adequate heat rejection by radiator. The durability of radiator under all road conditions is an important consideration during the design and development stage, specifically protection of radiators from impacting road debris and stones. A parametric study was conducted to investigate the damageability of radiators by small stone impacts. In this paper, radiator design parameters are studied for damage protection caused by stone impacts. The strain in the radiator material caused by stone impacts has been used as the measure of damageability. The parameters considered for the study are the fin thickness, fin pitch, tube height, tube thickness, tube nose radius, tube depth, stone size and stone speed. The results show that strain is dependent on fin thickness, tube thickness, stone size and stone velocity. Also strain is insensitive to Tube nose radius, tube construction type, and tube depth.

• PARAMETRIC STUDY ON IMPROVEMENT OF G4(1S) STRONG POST GUARDRAIL SYSTEM

  Jin Wu, Ala Tabiei - Department of Aerospace Eng. & Eng. Mechanics

  The G4(1S) strong post guardrail system is the most common guardrail system in the USA. Full- scale crash testing indicated that the vehicle rolled onto its impact side after exiting the guardrail system. This collision behavior of the roadside structure increases the occupant risk and is considered unsatisfactory for safety. Improvement of the G4(1S) guardrail system becomes an important issue concerned by the FHWA. The subject of this investigation is to understand the system behavior through parametric study and present a feasible approach for structural improvement. This paper provides a roadmap for simulation of highway safety structures. Some of the noteworthy observations are presented and discussed. The approach of reducing the embedment depth of post is investigated through both FE component simulation and full system crash simulation. This approach is recommended and is anticipated to be favorable for minimizing the risk of rollover of vehicles impacting the G4(1S) guardrail system.

• Particle Blast Method (PBM) for the Simulation of Blast Loading

  Hailong Teng, Jason Wang (LSTC)

  This paper presents a particle blast method (PBM) to describe blast loading. The PBM is an extension of corpuscular method (CPM), which is coarse-grained multi-scale method developed for ideal gas dynamics simulation. It is based on the kinetic molecular theory, where molecules are viewed as rigid particles obeying Newton’s laws of mechanics, while each particle in the particle method represents a group of gas molecules. Pressure loading on structures is represented by particle-structure elastic collisions. The corpuscular method has been applied to airbag deployment simulation where the gas flow is slow. For blast simulation where gas flow is extremely high, the particle method has been improved to account for the thermally non-equilibrium behavior. Furthermore, to better represent gas behavior at high temperature, co-volume effects have been considered. The particle blast method could be coupled with discrete element method, make it possible to model the interaction among high explosive detonation products, the surrounding air, sand and structure.

• Partitioning Effects on MPI LS-DYNA Performance

  Jeffrey G. Zais - IBM

  The MPI version of LS-DYNA includes several options for decomposition of the finite element model. In this paper, the use of these options will be explored, for both metalforming and automotive crash simulations for input decks with size ranging from small to very large. The effect on elapsed time performance and scalability will be measured for different partitioning options. In addition, performance characteristics of a workstation cluster will be evaluated.

• PC3: Crash and Blast Analysis Post-Processor for Simulations and Live Tests

  Hadar Raz (Plasan Ltd.)

  For crash and blast tests of vehicles and sub-assemblies, simulations play an important role in the prediction of the test results. Some of the most important results are the occupants’ injury criteria, which are calculated by simulating ATDs and their various joints, accelerometers, etc’. Often in a simulation/test there are few ATDs, and there is an increasing demand for post-processing of the injury criteria in an automated way, as well as correlating the results between simulation and test, thus enabling easier calibration of the simulation. We present PC3 (Plasan Criteria Computation and Comparison), a software tool developed by Plasan, which enables easy calculation of simulation and test ATD results, and correlation of said results. Currently the program is able to read simulation data from LS-DYNA® binout database, and various test databases, such as ISO text files, CSV files, HDF5 database files and some others. An example of criteria calculation for blast simulation and test data will be shown, along with correlation between the two.

• PCA-based sensitivity analysis of response fields using LS-OPT®

  C. Keisser (DYNAmore France), M. Hübner, T. Graf (DYNAmore), A. Basudhar, N. Stander (Ansys/LST)

  When performing an optimization, it is important to avoid introducing unnecessary variables that do not impact the design objectives and constraints. Such variables increase the design space size and lead to unnecessary sample evaluations, which can significantly increase the overall computation time or cost. A sensitivity analysis can be performed to quantify the significance of the variables; only the important variables are then used in the sampling and optimization, thus reducing the computational cost.

• PDC electrical cable modeling using TRUSS elements

  B. Pockszevnicki, V. Carvalho Rosa, R. Rajagopalan (Stellantis)

  This study aims to present a proposal for finite element modeling for electrical cables of a PDC to improve the response of the virtual analysis during design phase, establishing a good interation of electrical cables during crash tests. The objective of this study is to present types of elements and contact pairs that are capable of predicting the response of electrical cables.

• Pedestrian Head Impact, Automated Post Simulation Results Aggregation, Visualization and Analysis Using d3view

  Milind Shivaji Parab (FCA US LLC), Sreenath Mallela (FCA Engineering India Pvt. Ltd.), Suri Bala (ANSYS/d3VIEW)

  Euro NCAP Pedestrian head impact protocol mandates the reduction of head injuries, measured using head injury criteria (HIC). Virtual tools driven design comprises of simulating the impact on the hood and post processing the results. Due to the high number of impact points, engineers spend a significant portion of their time in manual data management, processing, visualization and score calculation. Moreover, due to large volume of data transfer from these simulations, engineers face data bandwidth issues particularly when the data is in different geographical locations. This deters the focus of the engineer from engineering and also delays the product development process. This paper describes the development of an automated method using d3VIEW that significantly improves the efficiency and eliminates the data volume difficulties there by reducing the product development time while providing a higher level of simulation results visualization. This method reduces post-simulation analysis time through automation thereby eliminating the effort and time of manual data management and visualization. d3VIEW is tightly integrated with LS-DYNA® and as the raw LS-DYNA data is processed on HPC, the resulting output data stored in d3VIEW server is considerably small and eliminates the issue of data bandwidth throttling when the output is to be made available across different geographical regions. Besides score calculation, the capability of d3VIEW has been challenged to include the generation of automatic opportunity chart that can highlight potential locations which require a minimal design change to improve overall score. In summary, d3VIEW platform provides significant benefit in reducing product development process and provides an efficient guiding tool in pedestrian head Impact analysis that can also be extended to other regulatory requirements.

• Pedestrian Hood Generation & Optimization Using Knowledge-Based Engineering

  Bill McLundie - Jaguar and Land Rover, Mike Twelves - Corus Automotive UK, Mike Howe - Jaguar Land Rover IT.

  Knowledge-based Engineering (KBE) has been used in industry in for some time. Companies such as Jaguar initially used KBE to automate well-understood, but repetitive, man-intensive engineering issues at the early phases of a programme. These were / are mainly based around geometrical problems (e.g. ergonomic design). Airbus (UK) in particular over the last few years has taken this to a new level by using ICAD as a method of not only generating geometry, but interacting with other existing programmes and creating a method of ‘glueware’ that takes initial input data, and runs through a design and analysis sequence that would normally take human processing much longer to achieve. The next logical step is to control the overall process using a piece of optimization software

• Pedestrian Protection: Use of LS-DYNA to Influence Styling and Engineering

  Bhavik R. Shah, Richard M. Sturt - Ove Arup & Partners,, Aram Kasparian - Arup

  This paper describes the use of LS-DYNA for pedestrian protection analysis. A testing procedure has been documented, that may form the basis of proposed future legislation in Europe. Testing is already carried out regularly as part of the European New Car Assessment Program. Large-scale changes in current styling and engineering practices are needed to pass the tests; often, such changes can be accommodated only if identified at concept or pre-concept stage. This paper includes validation of the impacter device models and illustration of their use in establishing design concept guidelines at a non-product-specific level. The limitations imposed on styling are potentially onerous, and are discussed in the paper.

• Pelvic Response Investigation of Lateral Loading Conditions using Finite Element Models

  Jaeho Shin, Costin D. Untaroiu, Jeff R. Crandall - University of Virginia Center for Applied Biomechanics

  Since the limited space between the car structure and an occupant makes it difficult to manage side impact energy, much biomechanical investigation has been done by subjecting the pelvis to lateral loading. In this study, the dummy finite element model was partially modified to verify the lateral pelvic loading by a rectangular shape impactor and used to explain in detail the previous investigation under iso-energy. In order to better understand the influence of impact mass and velocity under iso-energy, linear momentum and total energy conservation theories were introduced. Using driven equations from the theories and the simplified pelvis model, this study proved that the maximum internal energy levels should be different under iso-energy: the greater the impact mass, the less the internal energy level. This finding correlates with the previous pelvis loading investigation: the greater the impact mass, the less the pelvic loading, since it was shown that the impact loading is proportional to the internal energy. Thus, this study calculated the impact mass and velocity combinations to maintain the same internal energy level based on analytical solutions and finite element simulations. Closed values of the maximum pelvic forces were obtained when the calculated impact mass and velocity conditions were applied on the dummy lateral impact model. Furthermore, this methodology in conjunction with the analytical solution and the finite element simulation should be an appropriate way to set up the impact test configurations using manageable internal energy levels which may help to better understand the loading characteristics.

• Perforation of Composite Floors

  William Algaard, John Lyle, Conrad Izatt - Arup

  Rapid construction methods for multi storey buildings involve maximising the tasks that can be carried out simultaneously on site. The risks of construction workers, fitting out lower floors, being hit by large objects dropped during installation can be managed by understanding the protection provided by the intermediate floors. This paper describes a Finite Element based methodology for assessing the impact event using LS-Dyna. The aim of the method is to evaluate low velocity impacts of heavy objects dropped onto concrete floors in order to establish the potential for perforation. The methodology is validated by comparing the simulation results with empirical penetration formulae available for concrete structures and with some experimental results. It is concluded that the perforation limits can be predicted with good confidence, but that further experimental research in the low velocity range is desirable.

• Perforation of Metal Plates: Laboratory Experiments and Numerical Simulations

  Leonard E. Schwer - Schwer Engineering and Consulting Services, Kurt Hacker, Kenneth Poe - Naval Explosive Ordnance Disposal Technology Division

  The Naval Explosive Ordnance Disposal Technology Division has a requirement to establish a modeling capability to simulate render safe procedures for unexploded ordnance. To aid in establishing this capability, the Navy has initiated a research and development program that includes modeling studies, research on applicable impact related material parameters, and comparison of the modeling results with experimental results. This paper presents a summary of the progress during the first six months of this effort including a selection of laboratory experiments and their numerical simulation.

• Performance Analysis and Tuning of LS-DYNA* for Intel® Processor-Based Clusters

  George Chaltas - Intel Corporation, W. R. Magro - Intel Americas

  Using Intel software tools, including Intel® VTuneTM Performance Analyzer and Intel® Fortran Compiler, we analyze and tune the performance of MPP LS-DYNA* for clusters of Intel processors. We discuss the impact of various performance features of Intel processor-based systems, including vector/streaming instructions, on real LS- DYNA workloads. We compare single-precision performance and measure the impact of various cluster interconnect technologies.

• Performance Analysis of LS-DYNA® in Huawei HPC Environment

  Pak Lui, Zhanxian Chen, Xiangxu Fu, Yaoguo Hu, Jingsong Huang, Huawei Technologies

  LS-DYNA is a general-purpose finite element analysis application from LSTC. LS-DYNA is capable of simulating and solving complex real-world structural mechanics problems in an HPC cluster environment. In this paper, we are analyzing different areas that can impact on the performance of LS-DYNA by comparing different hardware components in Huawei HPC cluster environment. By evaluating the components, such as CPUs, network interconnects, system and software tuning on the latest Huawei HPC cluster solutions, we can demonstrate the sensitivity of the components on LS-DYNA performance which may help achieve higher productivity on LS-DYNA workloads.

• Performance Benefits of NVIDIA GPUs for LS-DYNA

  Stan Posey, Srinivas Kodiyalam - NVIDIA Corporation

  This work examines the performance characteristics of LS-DYNA for the latest CPU and GPU technologies available. The results are provided for system configurations of workstations for finite element models that are relevant to current industry practice. The motivation for these studies was to quantify the parallel performance benefits of LS-DYNA for the latest generation GPU from NVIDIA, the Tesla 20-series (codenamed Fermi) for implicit finite element models with 100K and greater DOFs, and for static and dynamic response load conditions.

• Performance Evaluation on the ALE Formulation in MPP LS-DYNA

  Yih-Yih Lin - Hewlett-Packard Company

  The ALE fluid-structure coupling capability in LS-DYNA has become the main tool to accurately simulate the airbag-inflating process. However, it is very time-consuming: Running serially, it has been observed to take more than ten days on various computer platforms. Hoping to obtain speedup by parallelization, LSTC has been making efforts to implement the ALE formulation with MPP LS-DYNA. In this paper, the scalability of this implementation, with the number of processors up to 64, is investigated on an HP Superdome. While the result indicates the current scalability of MPP LS-DYNA is inadequate and its improvement is needed, a preliminary study predicts the McKinley processor of the Intel Itanium Processor Family will make the goal of simulating a full airbag-inflating process within 24 hours possible.

• Performance Evaluation Using LS-DYNA Hybrid Version on the K computer

  Kenshiro Kondo, Hiroyuki Kanazawa (Fujitsu Limited), Kazuo Minami, Yukihiro Hasegawa (RIKEN), Hiroyuki Umetani (Japan Automobile Manufacturers Association, Inc.), Yu Setoyama, Takafumi Horita (Fujitsu Kyushu Systems Limited)

  In order to improve the accuracy of the car crash analysis, the number of elements in the analytical model has been increasing rapidly. A large-scale analysis using model with 10 million elements is slowly becoming popular. Some Companies actually has been adapting large models in their crash analysis nowadays. ́7KH K computer ́> @ D KLJKO\ SDUDOOHO V\VWHP FDQ FDUU\ RXW D FDU FUDVK analysis in several hours which other supercomputers would have taken several days to complete the analysis in the past. However in order to achieve such efficiency, the analytical jobs have to meet following conditions: use LS-DYNA Hybrid version; deploy Groupable contact function of LS-DYNA; and reduce contact definitions as much as possible. In this paper, we investigated the performance and behaviour of LS-DYNA Hybrid version using VHYHUDO WKRXVDQG SURFHVVHV RQ 37KH K computer ́. More specifically, due to the critical role of contact on the performance in a highly parallel system, we mainly focus on the following two aspects of contact calculation part throughout the discussion: the relationship of computational time with the number of contact definitions; and the effectiveness of Groupable contact. This paper gives brief descriptions DERXW 37KH K computer ́ RI 5LNHQ DQG /6-DYNA Hybrid version used in this study in Sections 2 and 3. Several issues that have been encountered when carrying out crash analysis on such highly parallel computing environment are discussed in section 4. The performance bottleneck and factors that hurt scalability are investigated in the next section using simplified model to reveal the effect on the performance with respect to various contact patterns and different number of contact definitions. The effects of Groupable contact function of LS-DYNA versus different contact patterns are studied in this section, too. In the end it is concluded that Groupable contact functions of LS-DYNA help to improve performance of crash analysis on highly parallel environment. A modification of the model to reduce number of contact definitions can boost the performance of LS-DYNA on the K computer.

• Performance of Large Scale Implicit Crash Analysis on Multicore Processor Systems

  Yih-Yih Lin, PhD

• Performance of LS-DYNA Concrete Constitutive Models

  Y. Wu, J. E. Crawford, J. M. Magallanes (Karagozian & Case)

  LS-DYNA provides several constitutive models for concrete. To provide some guidance in selecting a proper one for users who have limited experience on concrete, this paper reviews the background theory and evaluates the performance of three popular ones, namely, MAT072R3 (KCC), MAT084 (Winfrith), and MAT159 (CSCM). The basic performance of concrete constitutive models in capturing key concrete behaviors, such as post- peak softening, shear dilation, confinement effect, and strain rate enhancement, is examined through single element simulations including both uniaxial and triaxial load paths. Subsequent to this presentation, the models are applied in analyzing structures subjected to quasi-static, blast, and impact loads and the responses are compared with available test data in order to investigate their capability to predicting and reproducing actual structural responses.

• Performance of LS-DYNA on hpcLine Linux Clusters

  K. Altmeyer - Fujitsu Siemens Computers GmbH

• Performance of LS-DYNA on NEC-Clusters and new highend SMP-Systems

  Dr. A. Findling - NEC Europe GmbH

• Performance of LS-DYNA with Double Precision on Linux and Windows CCS

  Yih-Yih Lin - Hewlett-Packard Company

  Although the majority of LS-DYNA jobs are simulated with single-precision arithmetic, the more accurate and robust double-precision arithmetic has to be used for certain situations. Currently, most public LS-DYNA benchmarks are with single precision and few with double precision. As a result, users often try to extrapolate the performance of LS-DYNA with double precision from that with single precision. This paper shows that such extrapolations are often misleading. Furthermore, a comparative performance study on LS-DYNA with double precision, using all of the industry standard processors—Intel Xeon, Intel Itanium, and AMD Opteron—and the two major operating systems—Linux and Windows CCS—is presented to provide users with information for choosing the right configuration to run LS-DYNA with double precision.

• Performance of the Hybrid LS-DYNA on Crash Simulation with the Multicore Architecture

  Yih-Yih Lin - Hewlett-Packard Company, Jason Wang - Livermore Software Technology Corporation

  Using crash simulation models, we investigate the multicore performance of the newly developed hybrid LS-DYNA, a method whose speedup arises from both shared-memory and message-passing parallelisms. Theoretically, the hybrid method gains performance advantages over the traditional, message-passing-parallel (MPP) LS-DYNA for two reasons. First, the addition of shared-memory parallelism to the message-passing parallelism reduces the number of messages and their sizes dramatically, which in turn reduces latency and bandwidth requirements on interconnect. Second, the same addition enhances spatial and temporal localities for both code and data accesses, which in turn allows the size-limited cache to work more efficiently. Armed with this theory, we characterize performance of the hybrid method with respect to problem size, core count, core placement, and interconnect speed; thus provide users guidance on when and how to use the hybrid method efficiently. We also attempt to verify the theory by examining message patterns and the effect of core placement.

• Performance of the Hybrid LS-DYNA on Crash Simulation with the Multicore Architecture

  Yih-Yih Lin - Hewlett-Packard Company, Jason Wang - Livermore Software Technology Corporation

  Using crash simulation models, we investigate the multicore performance of the newly developed hybrid LS-DYNA, a method whose speedup arises from both shared-memory and message-passing parallelisms. Theoretically, the hybrid method gains performance advantages over the traditional, message-passing-parallel (MPP) LS-DYNA for two reasons. First, the addition of shared-memory parallelism to the message-passing parallelism reduces the number of messages and their sizes dramatically, which in turn reduces latency and bandwidth requirements on interconnect. Second, the same addition enhances spatial and temporal localities for both code and data accesses, which in turn allows the size-limited cache to work more efficiently. Armed with this theory, we characterize performance of the hybrid method with respect to problem size, core count, core placement, and interconnect speed; thus provide users guidance on when and how to use the hybrid method efficiently. We also attempt to verify the theory by examining message patterns and the effect of core placement.

• Performance Optimizations for LS-DYNA with Mellanox HPC-X Scalable Software Toolkit

  P. Lui, D. Cho, G. Shainer, S. Schultz, B. Klaff (Mellanox Technologies)

  From concept to engineering, and from design to test and manufacturing, the automotive industry relies on powerful virtual development solutions. CFD and crash simulations are performed in an effort to secure quality and accelerate the development process. The modern-day engineering simulations are becoming more complex and high in accuracy in order to model closely to the real world scenario. To accomplish such design simulations virtually on a cluster of computer systems, LS-DYNA® would decompose large simulation into smaller problem domains.

• Performance Optimizations via Connect-IB and Dynamically Connected Transport Service for Maximum Performance on LS-DYNA®

  Pak Lui, Gilad Shainer, Brian Klaff (Mellanox Technologies)

  From concept to engineering, and from design to test and manufacturing, the automotive industry relies on powerful virtual development solutions. CFD and crash simulations are performed in an effort to secure quality and accelerate the development process. LS-DYNA® relies on Message Passing Interface (MPI) for cluster or node-to- node communications, the de-facto messaging library for high performance clusters. MPI relies on fast server and storage interconnect in order to provide low latency and high messaging rate. The more complex simulation being performed to better simulate the physical model behavior, the higher the performance demands from the cluster interconnect are. The recently launched Mellanox Connect-IBTM InfiniBand adapter introduced a novel high-performance and scalable architecture for high-performance clusters. The architecture was designed from the ground up to provide high performance and scalability for the largest supercomputers in the world, today and in the future. The device includes a new network transport mechanism called Dynamically Connected TransportTM Service (DCT), which was invented to provide a Reliable Connection Transport mechanism — the service that provides many of InfiniBand’s advanced capabilities such as RDMA, large message sends, and low latency kernel bypass — at an unlimited cluster size. The paper will review the novel Connect-IB architecture, the new transport service, and their performance effect on LS-DYNA simulations.

• Performance Study of In Core Adaptivity in LS-DYNA®

  Houfu Fan, Brian Wainscott, Li Zhang and Xinhai Zhu (LST, an ANSYS company)

  Adaptivity is a key technique in metal forming applications, to save computation time while maintaining the accuracy of the result at locations of interest. Although very useful, the traditional implementation of adaptivity in LS-DYNA has certain inefficiencies in its execution. A new approach for adaptivity has been being developed for a couple of years in MPPDYNA. Recently load rebalance was also added into the code right after each adaptive step, which dramatically improves the computation efficiency. A performance study on the current status of this work is presented.

• Performing DOE Studies in Occupant Protection Using BETA CAE Tools

  Thanassis Fokylidis, Nikolaos Tzolas (BETA CAE Systems S.A.)

  One of the most important studies during the design process of a vehicle is its strength in different Crash scenarios. In particular the Safety of its occupants is one of the uttermost goals. Engineers try to cover as many possible cases from the reality by producing different simulations. DOE studies are inevitable to achieve that. ANSA and META, the pre and post processors of BETA CAE systems, offer a wide range of tools for the handling of ATDs, seats and seat-belts as well as tools for the automatic setup of different load-cases, the setup of DOE studies and the evaluation of the results. In this paper LS-DYNA® is used for a DOE study which is setup from the Optimization Tool of ANSA and examines how different parameters like the friction between the ATD and the seat-belt and between the ATD and the seat and the actual position of the dummy can affect the occupant's injury results.

• Phase Change Equation of State for FSI Applications

  Mhamed Souli, Ramzi Messahel, Lille University France;, Cyril Regan, Camille Ruiuc, Ingeliance Technologies, Agence de Bordeaux, France;, Bernard Cohen, Romain Ceyrolle, Sylvain Durel, EDF – Direction Production Ingénierie Marne la Vallée France

  To simulate fast transient phenomena, one must consider realistic compressible fluid models that take into consideration phase change, shock wave generation and its propagation. In an industrial framework, such phenomena occur mostly near industrial apparatuses such as pumps, propellers, impellers and control valves. The rapid collapse of cavitation produces strong shock waves that may harm the interacting structure. In this paper, we present the work on Homogeneous Equilibrium Model (HEM) phase change model implemented in the LS-DYNA® that is compatible its legacy ALE and FSI capabilities. Validation against experimental data is shown through previously published test case of cavitation in elastic water pipe.

• Phenomenological driven Modeling of Joints

  Matthias Bier, Herbert Klamser - Dr. Ing. h.c. F. Porsche AG, Andre Haufe DYNAmore GmbH

  In the construction of automobiles different technologies are used to join sheets. Today the most common method for connections is resistant spot welding. There are thousands of spot welds in body-in-whites, which are determining the behavior of the structure under crash conditions. New research is striving after replacing these thermal joints by adhesives or rivets for optimization of the production process. It is essential to ensure a cost saving and time optimized car development to reduce the required number of experiments by using precise simulations. For the quality of such simulation models accurate reproduction of the mechanical joint behavior is necessary. Because of the fact that the element size is bound by the time step in explicit finite elements schemes, a detailed model for the joints is not applicable in typical body-in-white simulations under crash conditions. For this reason simplified models using beam or solid elements have to be used to represent the connection. In the majority of load cases current modeling strategies do not show the required accuracy needed for design decisions. Therefore new ways of spot weld modeling and approaches for rivets modeling should be investigated. For spot welds several strategies of modeling exist. They all are based on the effort to reproduce the spot weld behavior by using specially adopted constitutive or structural models. For these models parameters have to be determined by comparing the maximum load under tensile, shear and peel conditions with corresponding numerical investigations. In the present paper it will be shown that a model with a relative small number of elements driven by a rigorous phenomenological approach can achieve better results. The quality of the proposed model will be evaluated by comparison of tests with KS2-specimen. In the field of self-piercing rivets an established modeling technique doesn’t exist. In this paper firstly capabilities of several modeling techniques will be investigated and secondly they will be compared with a model based on the aforementioned approach.

• Physical Appearance Evaluation of Automotive Seat Structre with J-SEATdesigner

  N. Ichinose, H. Yagi (JSOL)

  Seat styling is one of the important factors for automotive interior design. Automotive OEM company specifies 3D design to the seat supplier or their seat design section and the seat supplier designs 2d pattern to achieve desired 3D design as possible. To design the pattern from 3D seat design require a lot of experience, in many company, limited number of specialist can design the pattern based on their experience. These companies strongly desire the simulation system to design the pattern from 3D seat design. We had released J-SEATdesigner v2.0, in last June, which has basic features to set up seat manufacturing process like sewing/hooking/covering for LS-DYNA. v2.0 provides residual stress evaluation on seat fabric from sewing process simulation in LS-DYNA but the process simulation is not enough to evaluate physical appearance because of simplification of fabric 2d pattern. To evaluate physical appearance in LS-DYNA, the feature of J-SEATdesigner has been improved based on collaboration work with Japanese seat supplier. In this paper, new features for advanced sewing set-up in J-SEATdesigner will be introduced and new quantitative evaluation of wrinkle on manufactured seat surface will be shown. As I mentioned above, manufactured seat surface is one of the important factors for interior design, this means that it is important how the user feel the wrinkle on seat surface. This feeling is highly depending on fabric texture and color which cannot be considered in sewing process simulation. To resolve this issue, the sensory evaluation based on computer graphics technology is implemented in J-SEATdesigner. This sensory evaluation will also be introduced.

• Piercing of Aluminum Beverage Cans

  Brian A. Coon, Phanidhar Anugonda, John D. Reid - University of Nebraska-Lincoln

  An LS-DYNA finite element model was developed to analyze the structural behavior of an aluminum beverage can subjected to a piercing load applied to the sidewall of the can. Physical testing was performed to help verify the simulation accuracy. The piercing was intended to simulate the damage to a can that might occur during the manufacturing process. Impacts of 5 m/s and 10 m/s were performed with both blunt (flat) and sharp (45 tip) steel rods. It was found that separated elements with tied nodal constraints more accurately represent the behavior of the can subjected to a piercing load than merged element nodes. It was also found that the more crushing a can undergoes before piercing occurs, the more energy the can material absorbs. However, there is an upper limit to the crushing based on the speed and shape of the impactor.

• Plastic barrier for industrial applications - Characterization under impact loading using testing and Ls-Dyna®

  C. Goubel (LIER SA), E. Di Pasquale (Sim Tech), J. Pascual (BOPLAN)

  Safety structures are needed in industrial areas to protect people, machines or goods from forklift circulation. Steel roadside safety barriers are often chosen but the accuracy of these structures designed to restraint a light vehicle under a low angle but at high speed is not obvious. After several (even soft) impacts or contacts, this kind of devices suffers of a poor aspect and some parts have to be changed quite frequently. Plastic barriers developed by BOPLAN present the interest of elastic behaviour which allows to reduce significantly the number of repairs or maintenance operations on the one hand. One the other hand, the use of plastic structures is not a common choice and without any normative context concerning these products, commercial efforts are required to demonstrate the effectiveness of the structures. In order to help in the selection of the barrier type and in order to have scientific arguments, a meaningful collaboration combining testing, numerical simulation and mathematical models was set- up with the final aim to obtain a user friendly interface for structure selection as a function of conditions of use (Mass of forklift, customer regulation speed, etc...).

• Plastic Instability of Rate-Dependent Materials - A Theoretical Approach in Comparison to FE Analyses

  C. Keller, U. Herbrich (Bundesanstalt für Materialforschung und –prüfung)

  In FE simulations of dynamic events, the accuracy of numerical results strongly depends on the quality of the material models and parameters used. Material characteristics identified in static tests are not suitable or are of limited suitability for the description of the deformation behaviour of components and structures under dynamic loading. On this account, it is neces-sary to determine material properties in dynamic tests and to provide reliable input data for numerical simulations, e.g. by means of rate-dependent material models or flow curves. This can be achieved, for instance, by carrying out tensile tests with different loading rates, which, – statically or dynamically – are characterised by a material dependent plastic instability and necking of the specimens. In certain applications, the evaluation of the tensile tests in the range between initial plastic deformation and uniform elongation is sufficient. However, for the consideration of large deformation problems, it is essential to evaluate and establish ma-terial properties for the plastic deformation behaviour beyond the uniform elongation. Comparisons of results from experimental studies and FE simulations of dynamic tensile tests with ductile materials show significant differences in terms of the necking strain as well as the post-critical deformation behaviour. In order to conduct research regarding the cause of determined disagreements, the present contribution displays a theoretical approach describ-ing the instability in rate-dependent elastoplastic materials in comparison to results of nu-merical analyses. It is well known that under dynamic conditions, in addition to the depend-ence on the strain, the strain rate and inertia, both thermal softening and damage evolution in the material affect real deformation processes. In contrast, analytical and numerical ap-proaches allow for a specific selection and separate evaluation of the aforementioned influ-encing factors. This paper focuses on the plastic instability of rate-dependent, ductile materi-als. For this purpose, an analytical instability criterion under isothermal conditions is derived and applied. In conclusion, the theoretical findings are compared to simulation results from numerical studies and differences are discussed.

• Plasticity and Damage Modeling of the AA7075 Aluminium Alloy for Hot Stamping

  G. D’Amours, National Research Council Canada, Aluminium Technology Centre, Saguenay, Canada;, A. Ilinich, Ford Research and Innovation Center, Dearborn, Michigan, USA

  LS-DYNA® has several plane stress material models available for isothermal aluminum sheet stamping, most notably *MAT_3-PARAMETER_BARLAT, *MAT_BARLAT_YLD2000, and *MAT_KINEMATIC_HARDENING_BARLAT89. Recent models such as *MAT_BARLAT_YLD2000 based on Barlat’s YLD2000 yield surface accurately capture plastic flow and yield anisotropy of most aluminum sheet alloys. Some of these models are also applicable for non-isothermal forming. However, there are no general stress state models available for solid elements that can describe aluminum anisotropy and support temperature and rate depended parameters and hardening. Another problem is failure prediction as there are no temperature and rate sensitive failure criteria available for hot forming. This paper presents the development, implementation and validation of a user defined material model (UMAT) for the AA7075 aluminium hot stamping process which supports both shell and solid elements. It includes Hill plasticity with a non-associated flow rule and a damage model similar to GISSMO but extended to cover non-isothermal conditions. All simulations were performed using the implicit thermal and mechanical solvers in LS-DYNA which has several features for hot stamping modeling.

• Polypropylene Composites under Impact: Anisotropy, Mapping and Failure Criteria in Simulations, and Validation on a Part for Building and Construction Industry

  M. Nutini, M. Vitali (Basell Poliolefine Italia, a LyondellBasell Company), M. Benanti, S. Formolo (Polytech)

  Part and component design with Polypropylene Compounds can create several challenges for simulation methods. When Short Glass Fibers Polypropylene (SGF-PP) is considered, fiber orientation prediction, process-induced anisotropy and rupture criteria must be properly addressed in the structural analyses. The time frame is also relevant, as industrial environment simulations often need to provide fast solutions to designers in order to limit the time to market. Responding to the needs of a simulation tool for an early stage design, this paper describes a methodology based on an orthotropic material law (Ls-dyna MAT_157), embedded interactive criteria and a mapping tool (LS-DYNA ENVYO). This approach has been applied in the design of a part used in the building and construction industry, for which an experimental validation on an impact test has been also carried out. This study is here reported.

• Polyurethane Material Models for Simulating Leg-Form Impact in Explicit Transient Dynamics

  Joe Hassan - DaimlerChrysler, Peter Schuster, G. Frederick - Ford Motor Company

  Modeling of foams has become a very important task for automobile engineers due to the fact that compressible plastic foams are used throughout the interior and bumper systems of modern automobiles for safety enhancement and damage prevention. To date, most work has focused on predicting foam performance up to approximately 80% compression. However, in certain cases, it is important to predict the foam under maximum compression, or 'bottoming- out.' This paper uses one such case—a thin low-density bumper foam impacted by a pedestrian leg-form at 11.1 m/s—to investigate the 'bottoming-out' phenomenon. Multiple material models in three different explicit Finite Element Method (FEM) packages (RADIOSS, FCRASH, and LS-DYNA) were used to predict the performance. The finite element models consisted of a foam covered leg-form impacting a fixed bumper beam with a foam energy absorber. The predicted leg-form acceleration over time was then compared to the leg-form acceleration observed during a physical test. Within the finite element models solid elements using material types such as honeycomb, advanced foam curvilinear recoverable, strain rate foam recoverable, and low density foam were evaluated as to their accuracy in simulating ConforTM foam on the pedestrian leg-form and polyurethane energy-absorbing foam on a bumper beam under extreme compression or deformation conditions. Extreme deformation which occurs after 80% compression can cause excessive hourglassing of certain types of elements. During this extreme event many solid element material types will not exhibit the correct foam behavior, consequently the results lead to an incorrect prediction. This study attempts to determine the best material type to use during this type of large deformation impact.

• Porous Euler-Lagrange Coupling: Application to Parachute Dynamics

  Jason Wang, Nicolas Aquelet, Ian Do, Hao Chen - Livermore Software Technology Corporation, Benjamin Tutt - Irvin Aerospace Inc., Mhamed Souli - Laboratoire de Mécanique de Lille

  A newly developed approach for tridimensional fluid-structure interaction with a deformable thin porous media is presented under the framework of the LS-DYNA® software. The method presented couples a Arbitrary Lagrange Euler formulation for the fluid dynamics and a updated Lagrangian finite element formulation for the thin porous medium dynamics. The interaction between the fluid and porous medium are handled by a Euler-Lagrange coupling, for which the fluid and structure meshes are superimposed without matching. The coupling force is computed with an Ergun porous flow model. As test case, the method is applied to an anchored air parachute placed in an air stream

• Post-test simulation of airliner wing access panel subject to tyre debris impact

  R. S. Birch, D. Karagiozova, R. A. W. Mines - University of Liverpool, C. Bergler, M. Kracht - CADFEM GmbH

  The purpose of the investigations described in this paper is a simulation approach for tyre debris impact on wing access panels. Aircraft tyre rubber has a complex structure containing directional layers of nylon reinforcement embedded in the rubber matrix. Material properties of the compound have been derived from quasistatic compression and tensile tests with specimen cut in circumferential and axial direction of the tyre, i.e. with various reinforcement orientations. The Mooney-Rivlin material model describing the structural response of rubber, with embedded layers of elastic reinforcement cables, are used for the idealization of the tyre material. The material constants and reinforcement properties have been calibrated by the quasistatic specimen tests. The tyre mode then has been validated by dynamic impact tests of tyre fragments shot onto aluminium plates under an angle of 45 degrees. Measurements of transient strains of the aluminium plate shows good agreement with the simulation. For the full scale tests, tyre specimen with dimensions of 425x100x27mm were shot onto an access panel, fixed on a steel holding plate, at a velocity of about 110m/s and an angle of 45 degrees. Measurements were taken from strain gauges fixed to the inner surface of the outer cover and to the outer surface of the inner cover. Three tests with approximately the same parameters were carried out and showed good reproducibility of the strain curves. The mesh dependent parameters of the tyre model had to be re-calibrated for the full scale impact test simulation, to obtain a reasonable mesh density. The geometry of the tyre specimen has been matched according to the test. Simplifications that are assumed for the access panel idealization are e.g. the modelling of screws by a tiebreak contact formulation and the neglected rubber seal. The simulation results show a tyre deformation that is quite similar to the test. Also the calculation of the dynamic strains correlates well with the test. The tyre model proves to be robust and can be used for future analyses.

• Postprocessing of the 2020 EU-NCAP Frontal Impact Test in META

  N. Tzolas, D. Siskos (BETA CAE Systems)

  New cars are continuously becoming safer thanks to improvements in crash test regulations and standards. Currently crash test regulations and standards assess the safety performance of vehicles in frontal impacts under the precondition that the vehicle’s supporting structure is hit in such a way that the crumple zone absorbs energy during the crash. The General German Automobile Club (ADAC) accident research data shows, however, that in a car-to-car impact, the vehicle’s supporting structures might not hit in the same way as in the standard frontal impact tests. In these cases, the crumble zone of the vehicle cannot be fully utilized and this can lead to severe injuries. In 2010, the ADAC introduced a new test to assess the compatibility of vehicles in a car-to-car impact. In this test, a special honeycomb-shaped barrier is used, and its surface is scanned for evaluation after the test. This test with a progressive deformable barrier was named ADAC compatibility test or MPDB test.

• Practical Examples of Efficient Design Optimisation by Coupling VR&D GENESIS and LS-DYNA

  David Salway, GRM Consulting Ltd. UK., Paul-André Pierré, GRM Consulting Ltd. UK., Martin Liebscher, Dynamore GMBH, Germany

  With the ever increasing demand for the efficient use of materials to reduce manufacturing costs and product mass; the use of optimisation techniques have become common place in CAE. The optimisation techniques used for optimising in the non-linear domain, and those used for linear domain problems have until recently been distinctly separate philosophies. For instance topology optimisation would be used with linear static analyses, but could not be applied to non-linear problems. VR&D GENESIS provides a fully integrated linear static analysis and optimisation solver code. GRM have developed an interface so that GENESIS can be coupled to non-linear problems solved in LS- DYNA. The coupling allows the advanced analysis capabilities found in LS-DYNA to be coupled to the Topology, Topometry and Shape optimisation techniques of VR&D GENESIS. The paper outlines the processes already developed by GRM Consulting Ltd1 to allow this coupling, and the most recent developments. These developments allow the analysis methods available in LS- DYNA to be optimised by the optimisation methods available in VR&D GENESIS. The latest developments have taken the method from a research project to a code suitable for use in production level optimisation tasks The practical examples are intended to show how the use of this method allows non-linear domain optimisation to consider thousands of design variables, non-linear and linear load cases, whilst reducing the number of function calls required to converge.

• Practical Examples of Efficient Design Optimisation by Coupling VR&D GENESIS and LS-DYNA

  David Salway, GRM Consulting Ltd. UK., Paul-André Pierré, GRM Consulting Ltd. UK., Martin Liebscher, Dynamore GMBH, Germany

  With the ever increasing demand for the efficient use of materials to reduce manufacturing costs and product mass; the use of optimisation techniques have become common place in CAE. The optimisation techniques used for optimising in the non-linear domain, and those used for linear domain problems have until recently been distinctly separate philosophies. For instance topology optimisation would be used with linear static analyses, but could not be applied to non-linear problems. VR&D GENESIS provides a fully integrated linear static analysis and optimisation solver code. GRM have developed an interface so that GENESIS can be coupled to non-linear problems solved in LS- DYNA. The coupling allows the advanced analysis capabilities found in LS-DYNA to be coupled to the Topology, Topometry and Shape optimisation techniques of VR&D GENESIS. The paper outlines the processes already developed by GRM Consulting Ltd1 to allow this coupling, and the most recent developments. These developments allow the analysis methods available in LS- DYNA to be optimised by the optimisation methods available in VR&D GENESIS. The latest developments have taken the method from a research project to a code suitable for use in production level optimisation tasks The practical examples are intended to show how the use of this method allows non-linear domain optimisation to consider thousands of design variables, non-linear and linear load cases, whilst reducing the number of function calls required to converge.

• Practical Failure Criterion of Spot Weld for Crash Simulation

  J.-H. Lim, J. Ha, C.-Y. Oh (Posco)

  This paper proposed a practical failure criterion of spot welds for combined loading condition for crash simulation. The tests were designed to obtain the failure load of a spot weld under combined loading condition. The seven types of experimental test were conducted to obtain the component of spot weld failure criterion. The failure criterion consists of moment component including normal and shear force.

• Practical Optimization for Automotive Sheet Metal Components

  Xiao Chen, Omar Ghouati - Ford Research and Advanced Engineering Europe

  Forming simulation has now reached an acceptable level of accuracy. It is possible to predict the hardening, the thinning and required forces for sheet metal stamped parts and it is also possible to predict the geometrical defects such as springback, wrinkling and surface appearance problems. Sheet metal forming can therefore be used in a closed loop to help design of parts and required tools in order to achieve a pre-defined geometry and mechanical performance. The paper presents a practical optimization methodology applied to automotive sheet metal stamped parts. The goal is to automatically optimize tool geometry in order to achieve an optimal part. An optimal part is regarded as a part free of defects. The defects are classified in two categories: material and geometrical. Material defects prevent the forming of the parts which can be in the form of a premature failure or an excessive wrinkling. The geometrical defects prevent the formed part from being assembled to the body structure and are generally referred as “springback”. In order to establish this optimization methodology, available tools for optimization and automatic geometry modification were coupled to LS-DYNA [1]. A special attention was paid to the definition of the optimization problem: appropriate selection of design variables, definition of the response functions in order to characterize the possible part defects (material or geometrical) and specification of the required physical constraints. The developed methodology will be demonstrated on actual automotive components

• Predicting Mechanical Behaviour of Reinforced Plastic and Composite Parts

  S. Calmels (e-Xstream engineering)

  All the main industries worldwide are progressively adopting the usage of reinforced plastic and composite material for their product and have to face one major difficulty when it comes to design them: predicting the mechanical behavior of multi-phases and heterogeneous materials. On the structural side, each of these materials show a specific heterogeneous and anisotropic behavior in terms of stiffness, failure or electrical behavior as well as strain rate or thermal dependency fully driven by the microstructural organization of the reinforcements in the matrix. On the other side, the manufacturing process drives the final fibers orientation and distribution throughout the part. This means the design teams need a material and structural engineering technology able to create the link between the manufacturing process and the structural behavior of the components.

• Predicting the Dynamic Crushing Response of a Composite Honeycomb Energy Absorber Using Solid-Element-Based Models in LS-DYNA

  Karen E. Jackson - NASA Langley Research Center

  This paper describes an analytical study that was performed as part of the development of an externally deployable energy absorber (DEA) concept. The concept consists of a composite honeycomb structure that can be stowed until needed to provide energy attenuation during a crash event, much like an external airbag system. One goal of the DEA development project was to generate a robust and reliable Finite Element Model (FEM) of the DEA that could be used to accurately predict its crush response under dynamic loading. The results of dynamic crush tests of 50-, 104-, and 68-cell DEA components are presented, and compared with simulation results from a solid-element FEM. Simulations of the FEM were performed in LS-DYNA®* to compare the capabilities of three different material models: MAT 63 (crushable foam), MAT 26 (honeycomb), and MAT 126 (modified honeycomb). These material models are evaluated to determine if they can be used to accurately predict both the uniform crushing and final compaction phases of the DEA for normal and off-axis loading conditions.

• Predicting the results of the finite element simulation of a snowboarding backward fall with ODYSSEE

  D. Salin (CADLM), W. Wei, N. Bailly (Aix Marseille Univ)

  Skiing and snowboarding are very popular sports, associated with a high risk of injury (2.35/1000 skiing days in 2019 in France [1]). Among those injuries, the leading cause of death is the head injury which accounts for 5-10% of all injuries. Several studies have shown that helmet was effective in reducing the risk of head injury [2], [3] but the effect of the helmet in reducing certain types of brain injuries such as concussion is still unclear [4], [5]. To better evaluate and design effective helmets, it is critical to understand the head impact condition during the crash as well as the injury mechanism.

• Prediction of Dynamic Material Failure – Part I: Strain Rate Dependent Plastic Yielding

  M. Feucht (Daimler), R. Böhm (Karls­ruher Institut für Technologie), P. Du Bois (Consultant), F. Andrade, A. Haufe (DYNAmore)

  The dynamic behavior of materials plays a major role in crashworthiness. During a high speed crash event, the material undergoes different strain rates that may affect its constitutive behavior. For instance, in the first milliseconds of such an event, the strain rates near the contact region between the impacting and the impacted areas are extremely high. The strain rate then tends to rapidly decrease as energy is progressively dissipated during the crash.

• Prediction of Dynamic Material Failure – Part II: Application with GISSMO in LS-DYNA

  F. Andrade, A. Haufe (DYNAmore), M. Feucht (Daimler), R. Böhm (Karls­ruher Institut für Technologie), P. Du Bois (Consultant)

  As alluded in the first part of the present contribution, strain rate effects are quite relevant during a high speed crash event. If one intends to accurately predict failure under such conditions, it is important to properly understand and depict the underlying phenomena involved in such a scenario. For instance, the adiabatic heating that takes place during the plastic deformation process at high strain rates softens the material in such manner that the local plastic strain increases in critical zones. Also, localization is more pronounced in such critical zones due to the softening caused by adiabatic heating.

• Prediction of Failure Behaviors in Polymers Under Multiaxial Stress State

  S. Hayashi (JSOL Corp.)

  Polymers are used in an increasing number of automobile parts to improve occupant and pedestrian safety as well as reduce weight and cost. Under impact, these parts are designed to effectively absorb energy through large deformation and failure. Failure phenomena are very important to predict because structural strength is drastically changed or lost after failure occurs. In this study, puncture tests for polypropylene sheets were performed at various impact velocities and frictions, and failure locations and timings in the sheets were investigated. Puncture tests generate a multiple stress state in the sheets and this heavily influences the failure behavior of the sheet material. CAE crash simulations using LS- DYNA were conducted to successfully predict deformation and failure behavior under a multiaxial stress state.

• Prediction of failure on high strength steel in seat mechanisms simulation

  M. CHAUFFRAY, G. DELATTRE, L. GUERIN - Faurecia Automotive seating

  Tracks are the mechanisms which enable to translate the seat; they are key contributors in occupant safety as link between seat and car. With the current evolution of ecologic legislation, one of major automotive industry priorities is to decrease the product mass. To reach this objective, the use of high strength steels appears as a good solution with the drawback to be more brittle. In parallel, FEA models have to be more and more predictive in order to reduce the validation cost. In this context, rupture risk prediction appears as a strong need from design office and usual post-processing methods are not accurate enough to bring sufficient support to design teams. The solution chosen is a coupling between Ls-Dyna and the failure criteria crachFEM developed by MatFem Company. The evaluation of this risk is based on plastic strain evolution and stress state of the element. The methodology requires a specific characterization of the material to get information about the failure for different stress states. First application has been launched on ultimate strength subsystem on track. With dual- phase material, primary track failure mode is generally a profile rupture. First results highlighted correctly the area of rupture, but the ultimate strength was generally higher in FEA model than in the hard-test. This gap can be explained by the difference of scale between characterization of failure, which is a very local phenomenon, and the evolution of strain in simulation which is dependant of mesh size. Industrial crash model requirement (best compromise between accuracy and computation time: around 3mm mesh size) doesn’t permit to use mesh size needed for accurate rupture prediction. So “hybrid” modeling has been developed in order to have mesh size appropriate to MatFem analysis in useable computation time. With this approach the ruptures are well identified in term of areas, kinematics & ultimate strengths. Nowadays we are able, on this product, to predict with accuracy a risk of rupture on subsystem or on complete seat crash test.

• Prediction of fatigue damage by random vibration using isogeometric and finite element analysis

  S. Wang, R. Troain, L. Khalij (INSA)

  At present, the Finite Element Analysis (FEA) method is indispensable in the field of simulation technology, as this kind of numerical analysis method can assist engineers to predict results, which are often difficult to obtain from experimental tests. However, there exist some problems in terms of finite element mesh generation time and geometric representation. In this studying, we adopted a new numerical analysis method, Isogeometric Analysis (IGA) to develop static and dynamic analyses on two models, a notched plate and a wind turbine tower model in Ls Dyna software. From the static convergence analysis result, it is shown that IGA is more time-efficient compared with FEA. In terms of fatigue analysis results, IGA can predict the fatigue life corresponding very well to the fatigue life computed by FEA. It can be concluded that IGA is appropriate for the numerical analysis.

• Prediction of Impact Marks for a Stamped Panel with LS-DYNA

  Fen Ren, Yinong Shen, Z Cedric Xia - Ford Motor Company, David J. Wynn, Philip Ho - Livermore Software Technology Corporation

  Impact marks are the visible damage to the metal surface left by stamping tools sliding across a formed panel. The severity of such impact marks is an important quality measure in part buyoff, particularly for class A panels such as doors, body sides, hoods and deck lids. This paper presents a predictive simulation tool which has been developed to characterize and quantify the impact marks. It is based on the concept of accumulative frictional energy density between the panel/tool interface during a forming cycle. The tool itself provides an indication of the relative severity of the tooling impact on the panel surface, and can be used to fully assess production panel quality during draw development and also help a draw developer seek alternative design if necessary. The simulation tool has been implemented in LS-DYNA and the impact mark can be visualized and animated in LS-PrePost.

• Prediction of laser welding failure on seat mechanisms simulation

  M. Chauffray, G. Delattre, L. Guerin (Faurecia Automotive seating), C. Pouvreau (LIMATB)

  For some years, FAUREClA has chosen to industrialize LASER welding technology (Fig. 1 ) to weld it seat components, This choice is a consequence of global lightweight policy in industrial automotive world, To fully answer to this requirement Faurecia needs to join thinner parts using higher strength steels. On one seat sevenl tens of welding lines will be used to join parts with thicknesses from O.S mm to 5 mm. Conventional processes such as resistance spot we/ding or metal active gas have reached their limits where laser welding offered again high potential. The LASER process oHen higher flexibility in term of weldable materials, thichness and seams geometry. LASER is also faster than conventional process and does not need filler metal. On new structures, all weldings are done by one process instead of 2 or 3 in the past, For all those reasdns Faurecia, decided to invest in this high potential joining process. In Faurecia, several join types are used, overlap scan welding, T-joins welding, edge to edge... This study will deal only with overlap scan welding, which represents the most impo_ant part of the seat structure welding, but could be extrapolated to others, For this study, we need to distinguish mo hinds of welding rupture. First is the rupture of the joint itself called melted zone rupture. Second one is the rupture of the material at the welding faot. This rupture appears in an area called Heat Affected Zone (see Fig, 27 and represents the main welding failure mode observed during development phase.

• Prediction of Load-Bearing Capacity of Composite Cylinders with Impact Damage

  A. Cherniaev (University of Windsor), V. Komarov, S. Pavlova, A. Pavlov (Samara University)

  Impact damage induced by hailstone impact, tool, or equipment dropping can lead to severe reductions in composite structures’ load-carrying capacity. Aerospace companies and manufacturers of other products, in which composite materials are extensively used, spend considerable resources to determine the level of degradation of composite parts’ load-bearing capacity that have received impact damage during operation or during assembly, as well as the permissible degree of damage at which the replacement of an expensive structural member is unnecessary. Usually, such assessments are based on the integrated application of experimental destructive and non-destructive methods, which, in turn, also requires considerable financial and time investments. Understandably, the availability of a verified simulation approach capable of predicting the residual load-carrying capacity of composite parts with impact damage would provide significant costs savings and accelerate the decision making when such assessments are required. This preliminary study represents the first steps aimed at developing such a simulation approach using LS-DYNA software and is focused on the load-bearing capacity of damaged composite structural members designed to work primarily under the action of compressive loads.

• Prediction of Occupant Injury in an Out-of-Position Impact Using the Fluid Structure Interaction Capabilities in LS-DYNA

  Dr. P.O. Marklund - Engineering Research Nordic AB, Dr. B. Pipkorn, C.F. Lindh - Autoliv Research AB

• Prediction of Seat Deformation in Rear Crash Using LS-DYNA

  Biswanath Nandi, Dinesh Jain - Lear Corporation, USA

  It has always been a challenging task to simulate occupied rear crash for seating system. To design an ideal seat for resisting the load during rear impact is also a difficult task for the seat suppliers. Seat Suppliers are in continuous search of newer methods and techniques to reduce number of prototypes and testing cost. Analytical methods of predicting structural behavior using computer aided engineering (CAE) has been in place for quite sometime. A CAE method using LS-DYNA has been developed at Lear Corporation to simulate the rear impact and to predict the seat deformation. Rear Crash simulation has been performed on a six-way power driver seats using this procedure and back frame deformation predicted by the simulation has been validated to the physical test and a good correlation has been achieved. This paper discussed the methodology adopted and the correlation achieved.

• Prediction of Spot Weld Failure for Automotive Steels

  J. Lim, J. Ha (Posco)

  Spot weld failure has a great influence on the crashworthiness of a vehicle since an automotive body is mostly assembled by spot welding. Spot weld failure was not a serious problem when using low strength steel, but as the strength of steels increases, spot weld failure became a hot issue for crash performance due to the low spot weld strength compared to material strength. Nowadays, the car design is based on CAE, and the crashworthiness is evaluated from crash simulation. Spot weld failure is a critical factor causing the discrepancy between the actual crash performance and simulation result. Of course, car designers want to get accurate simulation results and design to avoid spot weld failure based on simulation. There are a lot of studies on spot welding failure, but It is necessary to further enhance the accuracy. In this paper, we study how to predict accurate spot weld failure by macroscopic analysis of spot weld failure. Normal, shear, bending, and torsional load components act on spot welds, and many spot weld failure model consider that they act independently, destroying the spot weld. In this paper, normal and bending load components are considered together because loading direction and plane of normal and bending components are same. Spot weld failure model that normal and shear load components act independently and there is the interaction of normal and bending components, is newly proposed. Here, torsional component is ignored because of low influence on an automotive body. Spot weld failure tests are performed for various automotive steels, and coefficients of spot weld failure models are derived. Since an automotive body has mostly heterogeneous stack-ups of the strength and the thickness, the spot welding failure tests for heterogeneous stack-ups are also performed and it is verified that the new model describes dissimilar stack-ups well. Compared to conventional models, the new model has an advantage in the simplicity and the accuracy. Finally, the predicting method of coefficients of spot weld failure models is developed to consider spot weld failure in the crash simulation without experiments.

• Prediction of Springback in CNC Tube Bending Process Based on Forming Parameters

  Levent Sözen, Mehmet A. Guler, Recep M. Görgülüarslan, Engin M. Kaplan - University of Economics and Technology

  CNC tube bending machines are commonly used in several industries such as automotive, aerospace and shipping. Especially in automotive industry, usage of tube formed geometries is common because they provide weight reduction without loss of strength. Obtaining desired dimensions and geometries is a necessity for design engineers to achieve high quality end-products. One of the easiest ways of having high quality tube formed end- products without the need of welding operations is using CNC tube bending techniques. The most common problems encountered during tube bending operations are thickness reduction, ovalisation, wrinkling and springback. Especially; springback which is defined as the deviation from the predefined bend angle after the bending operation performed is an undesirable condition that causes some difficulties in the assembly process. It depends on various geometrical parameters such as thickness of the tube, bend angle and effect of mandrel type used. Occurrence of springback is also dependent on forming parameters such as friction coefficient between dies and tube, internal pressure that is applied to the tube and axial loading. In the design stage, determination of springback and various parameters affecting springback behavior by experimental methods is quite cumbersome and costly. Therefore, prediction of springback by virtual methods such as finite element method (FEM) would shorten the time and reduces the cost of the pre-determination of springback.

• Prediction of structural response of FRP composites for conceptual design of vehicles under impact loading

  Sivakumara, K. Krishnamoorthy, Johannes Höptner, Gundolf Kopp, Prof. Dr.-Ing. H.E. Friedrich - German Aerospace Center (DLR e.V.)

  For the predictability of composite material behaviour under highly dynamic loads like crash, there is a need for better models reproducing the exact physics of failure mechanisms (matrix cracking, delamination, heat dissipation etc.). This belongs to the state-of-the-art research topics in numerical modelling. The conceptual design of vehicle structures however requires a qualitative understanding of the load-displacement characteristics, absorbed energy and the load distribution in other structural components and therefore may not necessarily demand a precise modelling of the physical behaviour. From the results of material testing of a variety of composite specimens, the necessary parameters for different LS-DYNA specific constitutive material laws are identified. After that, the modelling and simulation of simplified part samples have been carried out with dynamic loading conditions. The results are then compared with experimental testing of these part samples; hence the suitable parameters for composite design are identified. The scope, drawback and opportunities for numerical prediction using the considered constitutive laws and modelling schemes are then discussed based on the verification of the results.

• Prediction of temperature induced defects in concrete with LS-DYNA: cement hydration implementation and applications

  M. Bernardi, F. Kanavaris, R. Sturt (Arup)

  The cement hydration reaction has long been recognized as an important contributor to defects throughout the service life of concrete structures. As the hydration reaction is highly exothermic, and the thermal conductivity of concrete is relatively low, high temperatures and temperature gradients have special relevance in massive concrete structures. Massive concrete structures can endure significant cracking when temperature induced deformations are restrained. Uncontrolled cracking may compromise the structure durability and reliability, e.g. in massive concrete slabs for rail infrastructures or marine structures or the structure functionality, e.g. watertightness in liquid retaining structures or may even represent an aesthetically unacceptable defect for a concrete structure with demanding architectural finishing requirements. The heat generation and the consequent temperature rise in concrete structures is also a problem for the damaging effects on the concrete mechanical properties following deleterious chemical reactions such as Delayed Ettringite Formation (DEF). This chemical reaction is known to be associated with thermal fields in early-age concrete usually of the order 65°C to 75°C.

• Prediction of the Drop Impact Performance of a Glass Reinforced Nylon Oil Pan

  Peter H. Foss (General Motors Global Research & Development)

  As part of a cooperative development project between General Motors, BASF and Montaplast, a glass reinforced nylon oil pan was designed, analyzed, molded and tested. The oil pan was molded from BASF’s Ultramid® B3ZG7 OSI, an "Optimized for Stone Impact" grade of impact modified 35% short glass filled PA6. One of the development tests run on the pans was a drop impact test. In this report we will compare the predicted and experimental impact response using Digimat and LS-DYNA® with an anisotropic elastic-viscoplastic material model with failure. The Digimat material model was reverse engineered from high-rate tensile stress-strain data provided by BASF.

• Predictive Engineering Using DFSS of IBM Power9 System

  A. Alfoqaha, K. O’Connell, E. Campbell, M. Hamid (IBM)

  At IBM systems robust and reliable designs of servers and supercomputers are one of the main objectives. Predicting mechanical performance of servers, such as IBM Cognitive Systems' Power9 portfolio can be more challenging considering shorter development cycles, increasingly dense product design as well as advanced design features. The 2U version includes DDR4 RDIMM’s, Power9 hybrid land grid array (HLGA) processor modules, PCIe Gen3 and Gen4 slots, blowers, hard drives, and internal storage controller slots.

• Predictive fracture modelling in crashworthiness: A discussion of the limits of shell discretized structures

  André Haufe, Filipe Andrade, Karl Schweizerhof (DYNAmore GmbH), Markus Feucht (Daimler AG), Herbert Klamser (Dr. Ing. h.c. F. Porsche AG), Daniel Riemensperger (Adam Opel AG)

  For many years shell formulations were used extensively in crashworthiness applications in order to predict deformations and even rupture of thin shell-like structures. From a general shell theory point of view there are probably no arguments to change this in the near future, unless none of the basic shell assumptions like using them for thin structures, having plane sections and only minor stresses in thickness direction, will be violated. However, especially if damage, localization and eventually rupture is regarded, the aforementioned assumptions limit the applicability and eventually the means to calibrate such models. For instance, if the rupture strain in biaxial loading is to be calibrated from experiments one can have straight biaxial tests or penetration tests (i.e. the Nakazima tests). For both setups classical shell elements deliver the same value for triaxiality of 2/3. While this is the correct solution for a biaxial test, the Nakazima test suffers from the fact that lateral stresses applied to the sheet are not being covered at all in classical shell formulations. Hence the stress triaxiality and the loading angle are not predicted accurate enough . Another well-known issue is the inability of 5-parameter shells to correctly predict a correct stress state in localization zones due to the violation of the plane section assumption. The present paper will describe such limitations in detail, focus on different calibration techniques and resulting drawbacks in the final crashworthiness application. Furthermore, available remedies will be presented and discussed.

• Predictive Numerical Modeling of Foreign Object Damage

  Pierangelo Duó, David Nowell - University of Oxford

  During service aircraft engines may suffer foreign object damage (FOD) from ingestion of small hard particles and then are subjected to a range of HCF-LCF cycles. Manufacturers are seeking to improve the FOD tolerance of engines at the design stage and thereby reduce the costs of ownership. A design methodology is therefore required with which to assess the loss of fatigue strength resulting from FOD on blades or vanes. This work describes progress in the prediction of the residual stresses left from the impact in a specimen which resembles a compressor blade. The FE package LS-DYNA has been used to analyse the problem. Initially different material models were considered, each including a strain rate dependence, and a calibration based on a tensile test was performed. The Bamman Damage (Mat 52) was then chosen and used in the numerical model of impact on an aerofoil leading edge. The model has proved capable of recreating the damage geometry and gives a valuable insight into the likely residual stress distribution around the notch. A subsequent fatigue analysis of the impacted blade has been run using the same material model. A methodology based on a posteriori analysis and comparison with post-impact fatigue experiments has been used to confirm the results obtained.

• Preference-based Topology Optimization of Body-in-white Structures for Crash and Static Loads

  Nikola Aulig, Stefan Menzel (Honda Research Institute Europe GmbH), Emily Nutwell (Ohio State University SIMCenter), Duane Detwiler (Honda R&D Americas)

  Topology optimization methods are increasingly applied tools for the design of lightweight structural concepts in the automotive design process. Ideally, topology optimization provides the optimum distribution of material within a user-defined design space for a given objective function. In the vehicle design process, two important objectives are to maximize stiffness of components for regular working conditions and to maximize energy absorption in exceptional loading conditions, for instance in crash events. For these objective functions, the Hybrid Cellular Automata algorithm devises efficient structures in case of the separated disciplines, by heuristically aiming for a uniform distribution of energy densities. Recently, it was demonstrated that a concurrent optimization of crash and static load cases can be performed by a linear weighting, in which the user preference is separated from the scaling of the internal energies. In this paper, the approach is applied to the practical example of a vehicle body-in-white design, which is optimized for multiple crash and linear static load cases. By comparing resulting internal energies of different load case settings we demonstrate that the hybrid cellular automata algorithm with scaled energy weighting is capable to find a very good trade-off solution within a single concurrent optimization run.

• Preliminary Assessment of Non-Lagrangian Methods for Penetration Simulation

  Leonard E. Schwer - Schwer Engineering and Consulting Services

  Lagrangian, Eulerian, and Smooth Particle Hydrodynamics formulations are applied to the simulation of a rigid fragment impacting a concrete panel. An effort is made to keep much of the computational model constant across the simulations. All three methods are shown to be appropriate for this class of ballistic impact simulation. The results and conclusions are preliminary, but the paper serves as an introduction to these alternative forms of penetration analysis.

• Preliminary Assessment of Precast Reinforced Concrete Columns against Close-in Air Blast

  Swee Hong TAN, Hui Qi LOH, Jiing Koon POON (Ministry of Home Affairs, Singapore)

  In this contribution, a series of initial numerical results with respect to structural response of precast reinforced concrete (RC) columns subjected to close-in air blast are discussed. Although it is widely established that precast components generally possess limited blast resilience due to their non-monolithic connections, the underlying mechanisms are not well understood. To this end, the present study seeks to gain further insights via explicit modelling of a typical grouted sleeve connection, involving the bond behavior along reinforcement laps and the contacts between interacting concrete surfaces at the column base. Eurocodes have replaced British Standards as Singapore's prescribed building codes for structural design since 2015. CEB-FIP Model Code 1990 has served as an important basis for Eurocode 2: Design of Concrete Structures. In absence of experimental data, this study adopts the relevant guidance from the revised fib Model Code 2010, in attempt to incorporate the latest recommendations numerically. Two key departures are observed vis-à-vis the 1990 version. First, the fracture energy, which characterizes the tensile softening phenomenon, is now solely a function of mean unconfined compressive strength, i.e. independent of maximum aggregate size, while second, the local bond stress-slip analytical model that predicts the interaction between reinforcing bar and concrete, has largely remained the same, albeit with different input parameters.

• Preliminary Results for an Isogeometric Shell

  David J. Benson - Dept. of MAE, UCSD, Yuri Bazilevs, Thomas J. R. Hughes - ICES, The U.T. Austin

  Piecewise continuous Lagrangian polynomials are the traditional interpolation functions used in the finite element method. They work well for many applications, but they also have shortcomings for many important applications. For example, in metal forming, the dies are designed using CAD programs and their geometry is defined in terms of NURBS (non-uniform rational B-splines) which can not be exactly replicated with a piecewise continuous Lagrangian polynomial in all cases. Therefore, there is a geometric incompatibility between the desired shape and the kinematic range of the blank modeled with traditional finite elements. This paper presents initial results for a shell element formulation based on NURBS.

• Preliminary Results for an Isogeometric Shell

  David J. Benson - Dept. of Structures, UCSD, Yuri Bazilevs, Thomas J. R. Hughes - ICES, U Texas Austin

• Preliminary Study of the Behavior of Composite Material Box Beams Subjected to Impact

  Jason R. Smith, Lawrence C. Bank, Michael E. Plesha - University of Wisconsin-Madison

  LS-DYNA 940.2 was used to study the response of composite box beams subjected to oblique (or inclined) impacts by a rigid cylinder. The square cross-section composite beams were 1000 mm long with 50 mm by 50 mm nominal cross-sectional dimensions. The rigid cylinder had a 50 mm diameter and a 100 mm length and impacted the box beam on the top panel. The composite box beam and the cylinder were modeled with 3 mm thick Belytschko- Tsay shell elements. Material 54: MAT_ENHANCED_COMPOSITE_DAMAGE was used to model the orthotropic composite material used in the sidewalls of the box beam. In order to simulate an experimentally observed progressive “tearing” failure in the box beams during the impact events, spotwelds were used to model the corners of the beams (i.e. the joints between the four sides of the box beam). Spotweld failure parameters were calculated from the transverse tensile and in-plane shear strengths of the composite material. The benchmark analysis used for the study was one in which the rigid cylinder hit the beam at an incident angle of 25° to the horizontal axis at a velocity of 2 m/s. The coefficient of friction between the cylinder and the beam was 0.1. The results of the benchmark analysis were compared to results of analyses with various angles of impact, impact velocities, and coefficients of friction. Results were compared with respect to the displacement path of the cylinder, the angle of the path of the cylinder with respect to the horizontal direction (rebound angle), the change in velocity of the cylinder, and the resultant impact force on the cylinder. In general, the rebound angle and velocity of the cylinder appeared to have a rational dependence on the incident angle, the coefficient of friction, and the initial velocity.

• Preliminary Study on Modeling of the Deformation and Thermal Behavior of FSW using SPH Approach

  S. Patil, H. Lankarani (Wichita State University); F. Baratzadehl (National Institute for Aviation Research)

  Material flow in the solid-state Friction Stir Welding (FSW) is quite a complex process. Investigation of material flow can be carried out either by experimentation or by numerical simulation. However, compared to experimentation, numerical simulation is inexpensive, efficient and convenient, but quite challenging to model. The challenging issue in modeling FSW is to deal with the large deformations of the workpiece material. The Lagrangian simulations of FSW show that the severely distorted finite elements are caused due to the large deformation of the workpiece material, which makes the Lagrangian approach inappropriate for modeling FSW. A good alternative is to study it in a SPH environment. SPH formulations are used to overcome the shortcoming of Lagrangian formulations due to its continuous regimes. The basic idea of the SPH approach is that the mesh is obliged to follow material flow. Thereby the excessively distorted elements can be avoided as in Lagrangian formulations. In this paper, we fulfill this aim by using a SPH method. We also intend to do some preliminary experiments about weld strength .An important consideration in applying the SPH approach is an advection method which determines the mesh motion in every step of the analysis. Based on the simulation results, it is concluded that the material motion characteristics on the top surface and through the depth (volume) of friction stir welds have been made for the advancing and retreating sides. The motion trends are consistent with the reported published experimental evidence.The present paper organized as following. First SPH modelling performed .After that thermal history validated with FE model. Temperature history data is in good agreement with FE model.

• Preliminary Validation of a Detailed Finite Element Model of a 50th Percentile Male Pedestrian

  Wansoo Pak, Costin D. Untaroiu, Virginia Tech, Blacksburg, VA, USA;, Berkan Guleyupoglu, Bharath Koya, Scott Gayzik, Berkan Guleyupoglu2, Bharath Koya2, Scott Gayzik

  The pedestrian is one of the most vulnerable road users and comprised about 22% of the road crash-related fatalities in the world. While pedestrian protection regulations involving subsystem impact tests have been proposed, they cannot capture the whole vehicle-pedestrian interaction during car-to-pedestrian collisions (CPC). A few pedestrian finite element (FE) models representing 50th percentile male (M50) have been developed and validated previously. However, the existing FE models have several limitations, such as neglected/simplified body parts. To better predict crash-induced injuries observed in pedestrian accidents, a detailed pedestrian FE model was developed and preliminary validated in this study. The model geometry was reconstructed using a multi-modality protocol from medical images and exterior scanned data corresponding to a mid-sized male volunteer. The material properties of the pedestrian model were assigned based on the Global Human Body Models Consortium (GHBMC) M50 occupant model.

• Preliminary Validation of New Continuum-based Particle Gas (CPG) Method for Airbag Deployment Simulations

  Hiromichi Ohira, Richard Taylor, Shinichi Arimoto, Kosho Kawahara, Hiroyuki Umetani, Edouard Yreux, Inaki Caldichoury, Shinya Hayashi, Masato Nishi

  CPM (Corpuscular Particle Method) is widely used as a standard simulation technique for airbag deployment simulation among users for a long time. It is very fast and robust for most of the cases. On the other hand, we may need additional effort to reproducing the realistic gas flow around narrow area such as curtain airbag, vents, and so on. A new fluid solver (CPG ; Continuum-based Particle Gas) has been developing to reproduce it by directly solving the Navier-Stokes equation. 3 types of simple airbag tests are suggested and conducted to validate the CPG solver. Due to inviscid and free slip assumption for now, the gas frontal speed is faster than tests, but CPG showed a good result in terms of gas flow around narrow area.

• Preload Release in a Steel Band under Dynamic Loading

  Eyal Rubin, Yoav Lev (RAFAEL Advanced Defense Systems LTD.)

  A steel band is tightened around a thin walled steel cylinder. The assembly is exposed to different dynamic loadings including shock and vibration. While tightening, the circumferential stresses developed in the band, decrease as a function of the distance from the bolts and the value of the coefficient of friction between the band and the cylinder. The cylinder elasticity also affects the amount of force distribution in the band. A rigid cylinder will result in a maximal distribution of internal tension forces in the band. Experiments show that dynamic loadings, such as shock and vibrations, release the initial preload of the tightening bolts, and average the distribution of internal tension forces in the band. The extent of the change in the internal forces distribution depends on the level of the dynamic loading. While the motivation of the work was to find a lower boundary to the tightening force, a severe shock was chosen to demonstrate this Phenomenon. As a result from the severe shock, the internal tension forces at different cross sections converged to the same final uniform force. The level of this final force varies, depending on the coefficient of friction. The maximum possible release of the internal tension forces in the band, as a function of the coefficient of friction between the cylinder and band, and the rigidity of the cylinder, was determined using LS-DYNA® explicit simulation. This method can be used to determine the initial tightening force of any assembly, in order to assure that it stands dynamic environmental conditions.

• Prepreg forming, curing and structural analysis for an aero engine component

  Dennis Wilhelmsson, Jesper Eman, Vivekendra Singh, Anders Bernhardsson, Mats Landervik

  Carbon fibre composites have the potential of reducing weight and thereby the carbon footprint of an aero engine component due to the high strength and stiffness of the material relative to its weight. In this paper, a process simulation chain, consisting of forming, curing and structural simulations, is proposed. The demonstrator here is an outlet guide vain (OGV) which is part of an electric fan aero engine demonstrator, See Fig.1 below. This electric ducted fan (EDF) has been developed by GKN Aerospace Sweden in collaboration with the Royal institute of technology (KTH).

• Probabilistic Analysis of Process Chain “Forming to Crash“ Regarding Failure Prediction

  B. Özarmut, H. Richter (ThyssenKrupp Steel Europe), A. Brosius (Technical University Dresden)

  Numerical analysis of forming and crash processes is usually carried out deterministically. However, the variations of the parameters describing materials and processes cause significant deviations in the prediction quality. This observation becomes more important if the failure prediction in process chains like forming to crash is considered. Usually, the material and process parameters are identified by means of an inverse or a direct identification procedure using experimental data.

• PROBABILISTIC ANALYSIS OF UNCERTAINTIES IN THE MANUFACTURING PROCESS OF METAL FORMING

  H. Müllerschön, D. Lorenz - DYNAmore GmbH, W. Roux - Livermore Software Technology Corporation, M. Liebscher, S. Pannier - TU Dresden, K. Roll - DaimlerChrysler AG

  The purpose of this paper is to account for uncertainties in the manufacturing processes of metal forming in order to evaluate the random variations with the aid of FEsimulations. Various parameters of the Finite-Element model describing the investigated structural model are affected by randomness. This, of course, leads to a variation of the considered simulation responses such as stresses, displacements, and thickness reductions. On this, for the simulation engineer basic questions arise regarding: (1) the dimension of the range of variation of the simulation responses (2) the significance/contribution of the (input) parameters with respect to specific responses and (3) the reliability of the process design with respect to constraints (failure, damage, requirements, ...). In order to find solutions to these questions several methodologies may be applied that are available in the commercial optimization software LS-OPT (Stander et al. [5]). Some of the methodologies, such as Monte Carlo simulation, meta model based Monte Carlo simulation, stochastic fields, are discussed in this paper and are demonstrated by means of a metal forming problem.

• Probabilistic Assessment of a Stiffened Carbon Fibre Composite Panel Operating in its Postbuckled Region

  D. Elder, R. Thomson - Cooperative Research Centre for Advanced Composite Structures Limited, Australia

  This paper presents a probabilistic study on the behaviour and buckling capacity of a thin shell carbon fibre stiffened panel operating in its postbuckling region. The paper is a part of the ongoing world wide research into this phenomena being conducted by the CRC-ACS and many other interested parties including the EU FP6 Project COCOMAT. The aim of the research is to develop proven design methods that will allow an increased specific strength of stiffened composite structures commonly used in the civil aviation industry. Unlike their metal counterparts which can be reliably designed to operate with postbuckled loads, the use of similar composite parts for primary structures has not yet been widely adopted by industry. This is mainly due to the relatively brittle nature of composites which prevents significant yield based load paths being developed local to the stiffened regions of the structure. Using LS-OPT and LS-DYNA the study explores the probabilistic variations of a COCOMAT panel using a stochastic analysis. The response of the panel was the peak buckling load and the design variables included uncertainties in material properties, manufacturing tolerances and geometric imperfections. It was concluded that three of the four ply angles require accurate orientation during placement to produce a panel that will exhibit good repeatability for experimental testing. In addition the available computational methods in LS-DYNA to simulate buckling are reviewed and compared through the testing of a small baseline model.

• Process Automation for LS-DYNA Based Shock and Impact Studies (Drop Testing) in eta/VPG Environment

  H.M. Yang, Raymon Ju - Flotrend Corporation, Taiwan, H. Ouyang, T. Palmer - Engineering Technology Associates, Inc., USA

  Consumer products are many times used under extreme use conditions which have the potential to damage a device in a manner such that the internal components become damaged, and non-functioning. Designing engineers must consider these shock, impact and vibration conditions when designing products, as well as the shipping containers or packaging of the product for transport to the end user. In addition, there are many different variations of the impact condition, including height, and angle of impact. Drop Tests are performed to test physical prototypes for such inputs. LS-DYNA analyses can be used to simulate these tests, thereby reducing the number of tests and improving the product design prior to prototype construction. A case study of how process automation within eta/VPG has enabled engineers to consider many different drop test simulation scenarios in an efficient manner will be presented.

• Process Chain Forming to Crash: Efficient Stochastic Analysis

  Tanja Clees, Daniela Steffes-lai - Fraunhofer Institute for Algorithms and Scientific Computing SCAI, Martin Helbig - Fraunhofer Institute for Mechanics of Materials IWM, Karl Roll, Markus Feucht - Daimler AG

  During the fabrication of products, important material and process parameters, geometry and also external influences (e.g. room temperature) can vary considerably. It is known that they can have a substantial, even critical influence on the quality of the resulting products. Therefore, software tools and strategies supporting an efficient and thorough analysis of sensitivity, stability and robustness aspects as well as a multi-objective robust design-parameter optimization are necessary. This is especially true for parts of a car with a potentially critical influence in crashes as, for instance, the B- pillar which consists of several formed and connected blanks. We propose a new strategy, built upon several software tools as well as new material models, supporting an analysis of variations for the process chain forming to crash. The strategy roughly consists of the following parts and software tools: forming simulation (LS-DYNA) - - parameter sensitivity analysis (DesParO) - reduction/compression of input and output (DesParO) mapping (SCAImapper) - crash simulation (LS-DYNA) - - stability analysis (DIFF-CRASH) - sensitivity analysis (DesParO) - reduction/compression of input and output (DesParO) multi-objective robust design-parameter optimization (DesParO) - comparisons with physical experiments (as far as available) - Efficient, novel methods are proposed and employed for sensitivity analysis of simulation results on fine grids depending on parameter variations, for a reduction of the design space and the simulation results as well as for mapping an appropriately constructed data base of most influencing trends, not only comprised of thicknesses and strains, but also damage information. Including the latter turns out to be a crucial point. Results are shown, in particular, for a ZStE340 metal blank of a B-pillar. Comparisons to experiments demonstrate the abilities of the strategy proposed.

• Process Chain Forming to Crash: Efficient Stochastic Analysis

  Tanja Clees, Daniela Steffes-lai - Fraunhofer Institute for Algorithms and Scientific Computing SCAI, Martin Helbig - Fraunhofer Institute for Mechanics of Materials IWM, Karl Roll, Markus Feucht - Daimler AG

  During the fabrication of products, important material and process parameters, geometry and also external influences (e.g. room temperature) can vary considerably. It is known that they can have a substantial, even critical influence on the quality of the resulting products. Therefore, software tools and strategies supporting an efficient and thorough analysis of sensitivity, stability and robustness aspects as well as a multi-objective robust design-parameter optimization are necessary. This is especially true for parts of a car with a potentially critical influence in crashes as, for instance, the B- pillar which consists of several formed and connected blanks. We propose a new strategy, built upon several software tools as well as new material models, supporting an analysis of variations for the process chain forming to crash. The strategy roughly consists of the following parts and software tools: forming simulation (LS-DYNA) - - parameter sensitivity analysis (DesParO) - reduction/compression of input and output (DesParO) mapping (SCAImapper) - crash simulation (LS-DYNA) - - stability analysis (DIFF-CRASH) - sensitivity analysis (DesParO) - reduction/compression of input and output (DesParO) multi-objective robust design-parameter optimization (DesParO) - comparisons with physical experiments (as far as available) - Efficient, novel methods are proposed and employed for sensitivity analysis of simulation results on fine grids depending on parameter variations, for a reduction of the design space and the simulation results as well as for mapping an appropriately constructed data base of most influencing trends, not only comprised of thicknesses and strains, but also damage information. Including the latter turns out to be a crucial point. Results are shown, in particular, for a ZStE340 metal blank of a B-pillar. Comparisons to experiments demonstrate the abilities of the strategy proposed.

• Process chain simulation for “Die-Less-Hydroforming” including Welding and Forming using “DynaWeld” and “LS-DYNA

  A. Metzger, T. Ummenhofer (Karlsruher Institut für Technologie)

  Within the scope of “Die-Less-Hydroforming”, two or more thin metal blanks are joined at their edges by seal-welding. Thus, a two-dimensional flat “envelope” made of steel sheet results, that is formed into spatial structure through inflation of a medium (e.g. water) under continuous pressure increase. In comparison to conventional hydroforming-processes, no additional forming tool like a die or mould is used, leading to special phenomena like wrinkling or buckling during the forming process. The shape of the resulting 3D-structure is mainly controlled by the initial geometry of the blank and the forming pressure. A FEM-simulation of this special forming process with LS-DYNA was already introduced by the authors inter alia in [1]. Furthermore, a thermo-structural mechanical welding simulation of the assembly process of the blanks was developed with the software “DynaWeld” and the related solver “LS-DYNA”; see [2]. It is now assumed, that the residual welding stresses or welding distorsions resulting from seal-welding of the blanks have a strong and very sensitive influence on the “free” forming process regarding buckling and wrinkling in particular due to the small sheet thickness. First results are presented in this contribution from a simulation of a process chain for “Die-Less-Hydroforming” with simple geometries of double-layered blanks made of austenitic stainless steel (1.4301), that are joined by an arc welding process. In the first step, the joining of the double-layered blanks is simulated with “DynaWeld” and “LS-DYNA” which means the welding process by a thermo- structural mechanical welding simulation. Subsequently, a forming simulation of the double-layered blanks is performed, whereby the essential information from the welding simulation (that means distorsion, residual stresses, etc.) is transferred through a DYNAIN-file to the forming simulation. The aim is to determine the influence of the distorsion respectively the residual stresses resulting from welding on the formation process (that means in particular the emergence of wrinkles and buckles).

• Process development for multi-disciplinary spot weld optimization with CAX-LOCO, LS-OPT and ANSA

  Dr. Gordon Geißler - DYNAmore GmbH, Thomas Hahn - Audi AG

  The number of connection entities in modern car constructions is growing continuously. From that point of view, the identification of the most suitable structural behaviour of various car body configurations with respect to the number and the arrangement of connections becomes a challenge in automotive development. A standard simulation and optimization process was developed and established in a common project with the Audi AG and DYNAmore GmbH. The simulation model assembly process consists of a car body without any connection entities, a structured data format that describe the connections in detail and an automated process that realizes the connections using ANSA. All of these components are administrated and provided through the AUDI specific simulation data management tool CAx Load Case Composer (LoCo). This software is developed by DYNAmore and provides, among other innovative features, the possibility to parameterize components of the simulation model. With that ability at hand, it becomes possible to introduce parameters for the number of spot welds on a specified line. With the automated assembly process, the simulation engineer becomes able to investigate a number of spot weld configurations with a minimal amount of time and specific process knowledge. Connecting this parameterized assembly process with a structural optimization software like LS-OPT, provides the possibility to set up a systematic investigation of spot weld configurations with respect to any simulation response representing structural performance. The reduction of the total amount of connections under consideration of constraints can be one goal of such an investigation. Also the adjustment of a desired structural stiffness or the control of the deformation behaviour by the connection setup might be possible objectives in that context.

• Process Modeling of Freeform Incremental Forming Using LS-DYNA

  Feng Ren, Zhen Cui, Z. Cedric Xia - Ford Motor Company, Todd Slavik, Li Zhang and Xinhai Zhu - Livermore Software Technology Corporation

  Incremental Sheet Forming (ISF) is a manufacturing process for sheet metal prototyping where the blank is incrementally deformed into a desired shape by one or more stylus tools traveling along a prescribed path. Conventional ISF can be categorized into two types, Single-Point Incremental Forming (SPIF) where the sheet metal is formed from one side by a single stylus tool; and Double-Point Incremental Forming (DPIF) where a die positioned underneath a stylus tool pushes the sheet metal to wrap around the die. More recently a Freeform Incremental Forming (FIF) is developed at Ford Motor Company where two stylus tools synchronized in motion and deform the sheet metal from opposite sides as they are traveling to form a product shape. The new technology provides significant advantages for sheet metal fabrication process in terms of cost and flexibility because forming dies are completely eliminated and complex geometries can be formed. However the uniqueness of the process also brings significant challenges to its process design. This paper presents new capabilities developed in LS-DYNA for simulating Freeform Incremental Forming (FIF). The rigid stylus tools can move arbitrarily in both translational and rotational Degrees-of-Freedom (DOF). Challenges for numerical simulations and their modeling techniques are addressed in the paper. Numerical and experimental examples of Freeform Incremental forming processes are presented. It is demonstrated that the simulation results correlates very well with laboratory measurements.

• Process Modeling of Piercing Micro-hole with High Pressure Water Beam

  Jiang Hua, Xiaomin Cheng, Rajiv Shivpuri - The Ohio State University

  During the fabrication of very small or fine hole, usually referred to as micro-hole, technical difficulties often arise due to limitation on the precision capability of tooling systems including those associated with alignment. The present project attempts to develop a new process for piercing micro-hole, using high pressure water beam. In this paper, a numerical model for the micro-hole manufacturing is developed which provides helpful insight into the mechanics of the micro-hole forming process and the tooling design. The ALE (Arbitrary Lagrangian-Eulerian) method of dynamic FEM model is used to simulate water hammer and the water beam penetration into the workpiece material. An experiment for hydro-piercing process is also developed to validate the numerical model. The effects of micro-hole parameters, diameter and workpiece thickness, and water pressure on the micro-hole formation are investigated. It is found that the fracture occur near the die corner in workpiece material and that the pressure increases dramatically when the ratio of hole diameter to thickness is less than 1.

• Process optimised FEA- Calculation for Hydroforming Components

  Michael Keigler, Herbert Bauer - University of Applied Sciences, Aalen, Germany, Richard Hall - University of Wolverhampton, UK, Prof. Musa Mihsein - De Montfort University, UK

• PROCESS PARAMETER SENSITIVITY STUDY ON TUBE HYDROFORMING

  X.M. Chen - United States Steel Corporation, K. Palanisamy - ETA, Inc., X.H. Zhu - Livermore Software Technology Corporation

  Finite element analysis (FEA) has proven to be a useful tool for stamping process analyses. FEA has also been used increasingly for hydroforming analysis in the industry. In this paper, some examples for various hydroforming process simulations using LS-DYNA are presented. The effects of material characteristics and process parameters on tubular hydroforming are discussed. A sensitivity study has been conducted on a simple geometry. Three steel grades: DS, HSLA and DP, and process parameters such as internal pressure, end feeding and lubricant are included in this study. Simulation results are also compared with experimental data. It is demonstrated that computer simulation can be used as an aid for optimal selection of those parameters to reduce time and cost in tool tryout. In addition, some of the simulation limitations are discussed in this paper.

• Process simulation in LSDYNA from the viewpoint of a materials supplier: towards an integrated approach for performance and process

  Christos Derdas, Raoul Abas, Michael Klotz

  Electromobility and sustainability are the current megatrends that drive the market development of the automotive industry. In order to be conforming to these megatrends, one solution exists, and this is the lightweighting of automobile structures. More specifically, with advancing metal technology, the trend is for automotive Original Equipment Manufacturers to reduce the thickness of outer, non-load bearing panels of closures like doors and hoods. However, reducing the thickness of such panels creates an additional challenge, this being retaining both the Class A surface finish and the localized stiffness, which is crucial as it defines the experience of the end-user of the automobile. This can be achieved by leveraging 2D rubber or epoxy reinforcements that enable the bridging of the weight reduction and the localized stiffness competing requirements. Outer panel thickness reduction, however, makes them more prone to process induced permanent deformations due to temperatures of the oven required for curing coatings and paints.

• process2product simulation: Closing Incompatibilities in Constitutive Modeling and Spatial Discretization with envyo®

  Christian Liebold, Dr. André Haufe, DYNAmore GmbH, Industriestrasse 2, D-70565 Stuttgart, GER

  Within the automotive sector but also other industries, closing the simulation process chain from manufacturing towards the final crushing analysis becomes more and more important since it is well understood that the manufacturing process influences material properties such as initial damage, pre-stresses, induced plastic strains, differing thicknesses, or locally varying engineering constants. In LS-DYNA®, it is possible to consider such discontinuities using respective THICKNESS, BETA or ORTHO – options on element level, and *INITIAL_STRESS_SHELL/SOLID cards to introduce locally varying properties on an integration point level.

• Processing of Equality Constraints for Implicit in LS-DYNA v. 970

  C. Cleve Ashcraft, Roger G. Grimes, Bradley N. Maker - Livermore Software Technology Corporation

  LSTC is committed to building an implicit capability into LS-DYNA that is as capable as the flagship explicit capability. Over the years LSTC has added many different types of constraint handling capabilities in explicit that now have to be handled by implicit. The vast majority of these constraints are equality constraints imposed on the linear or nonlinear solution required at each time step. We will describe a new approach for handling equality constraints that has allowed us to robustly process them without placing unnecessary restrictions on how the user poses the constraints. Our new approach effectively and efficiently processes the constraints for the linear, nonlinear, and eigenvalue problems that have to be solved by the users of Implicit LS-DYNA. We compute a transformation based on the Jacobian matrix of the constraint equations and apply that transformation to form a reduced stiffness and, if necessary, reduced mass matrices. The transformation is also used to transforms vectors from the unconstrained space to the constrained space and back again. The only restriction placed on the structure of the constraint matrix is that it is full rank. We will also highlight the various constraints now supported for implicit solution in LS-DYNA v. 970 and demonstrate the solution of some problems illustrating these constraint features.

• Processor Count Independent Results: Challenges and Progress

  B. Wainscott, Z. Han (LSTC)

  When a different number of cores is used to run the same model in MPPDYNA, different results are generally produced. We discuss a couple of different reasons for this, and why it is to be expected in a parallel program. Work is in progress to offer options which work around this issue, and results of some test problems are presented.

• Productive Environment for Quick CAE Modeling and Simulation – Visual Environment

  Shivakumara H Shetty, Velayudham Ganesan, Nagesh B L, Jean Louis Duval - ESI Group

  The current trend of Product Development Cycle needs to be optimized to meet the growing demand for robustness, quality and fast to market. High competition, mandatory regulations and global norms are forcing the engineers and researchers to evolve with innovative ideas and solutions to meet demands. CAE plays a crucial role in the product development cycle where the FE modelling and simulations are preformed for virtual evaluation of the products. Commercially available CAE tools and software are used for such problems. ESI’s EASi-CRASH application is one of the tools widely used in CAE world mainly by automotive industries. In order to meet such CAE users expectation of fast paced product development, ESI’s Open VTOS (Virtual Try-Out Space) solution provides a platform for achieving the desired productivity and results in the virtual prototyping environment. Visual-Environment (VE) is the major enhancement of EASi-CRASH application. Virtual Prototyping methodology has made significant contribution in enhancing the productivity, reliability, usability and robustness. VE is an integrated suite of solutions, which has different contexts seamlessly linked for Crash and Safety simulation. Visual- Crash DYNA (VCD)-a pre processor for LS-DYNA, Visual-SAFE-an advanced pre-processor for safety features, Visual-Mesh a general purpose mesher, Visual-Viewer (VVI)-a general purpose plotting and simulation application, Visua-Life Nastran (VLN)-a general purpose pre processor for NASTRAN, Visual-Process Executive-an application for process customization and repetitive tasks automation are the contexts to name a few. This paper describes the key modelling features and usefulness of Visual-Environment in Crash and Safety simulation with productivity examples and process automation.

• Productivity and Quality of LS-DYNA® Analyses: Implementing a Tailor-made Software Solution for the Transport and Storage of Radioactive Materials

  Gilles Marchaud, Valérie Saint-Jean, ORANO TN, Montigny-le-Bretonneux, France

  For more than 50 years, ORANO TN (formerly AREVA TN) has been supplying customer-focused, innovative transportation and storage solutions for radioactive material with the highest levels of safety and security. Within a context of stringent regulations, ORANO TN performs LS-DYNA analyses to evaluate the crashworthiness of casks and to reduce the number of costly real tests. Continuous effort is being made to improve these analyses. Part of the effort is dedicated to Verification & Validation, i.e. ensuring that LS-DYNA, along with well-defined methodologies, provides realistic results.

• Productivity Gain in Crashworthiness Simulation EASi-CRASH for Complete Safety and Crash Modeling for LS-DYNA

  Shivakumar Shetty, Petter Sahlin - ESI Group

  The pre and post-processing for crashworthiness and safety simulation in automotive development projects is constantly changing. New functionality of the solver requires evolutionary updates, while the paradox of combining reduced lead times with an ever increasing range of regulatory tests calls for more dramatic improvements and innovative approaches. Hence the changes, the underlying need is constant – to increase productivity in model build-up, analysis and results evaluation for crashworthiness and safety simulation. This paper will present what is essential for productivity gains in crash modelling and results evaluation for simulation with LS-DYNA - exemplified with use cases from OEMs and major safety suppliers.

• Progress on GPU Implementation for LS-DYNA Implicit Mechanics

  Roger G. Grimes, Dr. Robert F. Lucas, and Gene Wagenbreth - Livermore Software Technology Corporation

  Graphics processing units (GPUs) are ubiquitous devices designed to improve the end-user experience in mass market arenas such as gaming. High-end GPUs have an order of magnitude more computing power than their hosts, and are thus attractive candidates for accelerating compute bound applications such as MCAE. This talk will present how we have extended LS-DYNA to utilize Nvidia Tesla GPUs for implicit mechanics. We will describe the target environment along with performance results on a range of benchmark problems. The performance results will illustrate when it makes sense today to utilize the GPU, and when it does not.

• Progressive Damage Modeling of Plain-Weave Composites using LS-Dyna Composite Damage Model MAT162

  Dr. Bazle A. Gama, Prof. John W. Gillespie Jr. - University of Delaware, Dr. Travis A. Bogetti - US Army Research Laboratory

  Progressive damage of plain weave S-2 Glass/SC15 composites under in-plane tension, compression, and shear, through-thickness tension and compression, and transverse interlaminar and punch shear loading is presented for a unit single element using the MAT162 composite damage model in LS- Dyna. While the detail formulation of the MAT162 material model can be found in the Keyword user's manual [1], the main objective of this paper is to describe a methodology to determine a set of softening parameters using a unit single element analysis. The analytical formulation of post-yield damage softening is presented with stress-strain behavior of a single element under different loading conditions. Since MAT162 uses four different softening parameters, i.e., AM1 and AM2 for fiber damage along material directions 1 and 2, AM3 for fiber shear and crush, and AM4 for matrix crack and delamination; the choice of a set of these four AM values is not obvious. The stress-strain plots presented in this paper will serve as an additional user guide to select a set of AM values for a specific material and a specific application. Unlike linear-elastic design of composite structures with max-stress/strain or quadratic failure theories, modeling the post-yield softening behavior allows one to simulate the energy absorbing capabilities of a composite structure. It is important to choose a set of AM values which represent a material's behavior through single element analyses and validation of the model with other quasi-static and dynamic experiments. A poor choice of the AM values may lead to prediction of either higher or lower energy absorption capabilities of the composite structure. In order to accomplish this objective, the single element analysis is presented with appropriate loading and boundary conditions. Model validation studies simulating static and dynamic experiments can be found in [2], and further studies will be presented elsewhere.

• Progressive Damage Modeling of Plain-Weave Composites using LS-Dyna Composite Damage Model MAT162

  Dr. Bazle A. Gama, Prof. John W. Gillespie Jr. - University of Delaware, Dr. Travis A. Bogetti - US Army Research Laboratory

  Progressive damage of plain weave S-2 Glass/SC15 composites under in-plane tension, compression, and shear, through-thickness tension and compression, and transverse interlaminar and punch shear loading is presented for a unit single element using the MAT162 composite damage model in LS- Dyna. While the detail formulation of the MAT162 material model can be found in the Keyword user's manual [1], the main objective of this paper is to describe a methodology to determine a set of softening parameters using a unit single element analysis. The analytical formulation of post-yield damage softening is presented with stress-strain behavior of a single element under different loading conditions. Since MAT162 uses four different softening parameters, i.e., AM1 and AM2 for fiber damage along material directions 1 and 2, AM3 for fiber shear and crush, and AM4 for matrix crack and delamination; the choice of a set of these four AM values is not obvious. The stress-strain plots presented in this paper will serve as an additional user guide to select a set of AM values for a specific material and a specific application. Unlike linear-elastic design of composite structures with max-stress/strain or quadratic failure theories, modeling the post-yield softening behavior allows one to simulate the energy absorbing capabilities of a composite structure. It is important to choose a set of AM values which represent a material's behavior through single element analyses and validation of the model with other quasi-static and dynamic experiments. A poor choice of the AM values may lead to prediction of either higher or lower energy absorption capabilities of the composite structure. In order to accomplish this objective, the single element analysis is presented with appropriate loading and boundary conditions. Model validation studies simulating static and dynamic experiments can be found in [2], and further studies will be presented elsewhere.

• Projecting Performance of LS-DYNA Implicit for Large Multiprocessor Systems

  Pramod Rustagi, Ilya Sharapov - Sun Microsystems, Inc.

  We use a benchmark dataset of a jet-engine impeller to study the performance characteristics of the LS-DYNA Implicit solver, as a function model size and the number of processors available in the system. We analyze a range of models with an increasing number of fans in the jet-engine impeller, from the smallest model of three fans composed of 300,000 nodes to the largest model of ten fans with 1 Million nodes. The resulting stiffness matrices are of sizes .9 and 3 Million Degrees of Freedom (DOF) respectively. These sizes are typical for today's LS-DYNA runs, but in the coming five years, model sizes will to grow upwards of 50 Million DOF. In addition, the computational system available at that time will offer much higher degree of parallelism. In this paper we estimate the performance and scalability of large LS-DYNA runs on these future machines.

• Pyheart-lib: A Python Library For LS-DYNA Multi-Physics Heart Simulations

  Martijn Hoeijmakers, Karim El Houari, Wenfeng Ye, Pierre L’Eplattenier, Attila Nagy, Dave Benson, Michel Rochette

  Physics-based computer simulations of the heart are gaining rising interest for optimizing the design of medical devices and for its treatment prediction and planning. LS-DYNA offers a powerful framework for modeling cardiac electrophysiology, mechanics, and fluid dynamics, as well as the coupling between the three physics. However, its wider adoption is hindered by several requirements among which: knowledge in cardiac function in health and pathology, expertise in numerical simulation, appropriate right modeling choices for the target application, availability of realistic heart geometries. In this paper, we present a free to use python package that allows for the generation of physiologically accurate heart models in an automatic and modular fashion. The architecture is organized in an abstract form that allows users to easily choose between the different physics, anatomical chambers of interest and parameters of interest and export the LS-DYNA keyword files ready for simulation. We also introduce the relevant heart modeling features that are available in LS-DYNA and present two exemplary models generated by the package: a full electrophysiology heart model and a bi-ventricular mechanical model.

• qd – Build your own LS-DYNA® Tools Quickly in Python

  C. Diez, Lasso GmbH Germany

  CAE is a large field with many different use cases. This high diversity yielded a large variety of tools, which help us engineers to achieve a high working performance every day. Unfortunately the situation arises, where engineers need to solve an additional, sometimes client or company-specific tasks, where no tool yet exists. Many of these tasks require usually only one key element: comfortable and fast data access.

• Qualification of *Constrained_Lagrange_In_Solid command for steel/concrete interface modeling

  L. MOUTOUSSAMY, G. HERVE, F. BARBIER - Tractebel Engineering France

  Modeling reinforced concrete is an important requirement for civil engineering calculation. Particularly, engineers need to have information about both rebar and concrete. The need for modeling them separately comes obviously to allow local and global analysis of a reinforced concrete structure. This paper focuses on the validation of modeling of reinforced concrete with the CSCM material and Constrained Lagrange In Solid to tie the rebar. The interest for this method is the possibility to mesh separately concrete and rebar and to avoid overmeshing caused by the concordance between concrete and rebar nodes. This coupling is commonly used to model Eurocodode 2 compatible reinforced concrete. In order to validate the method, a comparison between analytical and numerical results is presented for simple civil engineering frames (beam and portal frame). This first study is made with a pseudo-dynamic loading. First, a four points bending test is presented for different case of steel rate in order to validate that momentum in a section is correctly represented when the concrete is at the maximum damage rate. Then, in a second step, a bending test on a common framework is presented to confirm that the momentum is correctly transmitted in articulation. A particular attention is accorded to the formation of plastic hinges.

• Qualification of Launcher Tank Dynamic Behaviour through Vibratory Experiments using Discrete Element Spheres

  Tess Legaud, Vincent Lapoujade, DynaS+;, Pierre-Louis Chiambaretto, Sinh Khoa Nguyen, Yves Gourinat, Université de Toulouse;, Valia Fascio, ATECA

  Liquid hydrogen associated to liquid oxygen is one of the highest specific impulse propellant widely used for launchers propulsion. However, due to the fluid high explosiveness, full scale vibratory tests on tanks filled with liquid hydrogen is not advisable. The EASYNOV TANKYOU project, financed by the French Occitanie region aims at finding a safe substitute metamaterial that should be able to represent the liquid hydrogen vibratory behaviour in a fully filled tank. The key concept that frames this project consists in using a pre-stressed granular medium. The main objective is to find the granular medium properties that enable to fit the modal shapes and frequencies of the tank filled with this granular medium to the one filled with liquid hydrogen.

• Quasi-Static Finite Element Analysis (FEA) of an Automobile Seat Latch Using LS-DYNA

  Song Chen, Yuehui Zhu - Fisher Dynamics Engineering

  In the present automotive industry, all suppliers and OEMs are focusing on designing, developing and manufacturing products and automobiles with higher quality, lower cost and faster delivery to the customers. The automobile industry has placed a significant amount of efforts including time and funding into developing products that can meet these challenges. This is probably one reason that in recent years Finite Element Analysis (FEA) has been widely used and become a mainstream design and developing process in automotive industry. This is especially true in the Noise, Vibration, Harshness (NVH) and safety fields. This paper presents a project of Fisher Dynamics in the system level Quasi-static FEA using LS-DYNA effectively directed the design of an automotive seat latch to meet the stringent high load requirements. The analysis successfully predicted the results of physical tests including the ultimate load. Hence the company was able to deliver a design in conformance with the specifications of the customer on time.

• QUASI-STATIC LIMIT LOAD ANALYSIS BY LS-DYNA IN COMBINATION WITH ANSYS

  Wilhelm Rust, Ulrich Franz - CAD-FEM GmbH

  It is shown when and how quasi-static limit load analyses can be performed by a tran-sient analysis using LS- DYNA. Then we focus on the remaining benefits of implicit analysis and how a proper combination of ANSYS and LS-DYNA can be used to prepare the transient analysis by common preprocessing and static analysis steps. Aspects of discretization, solution control, consideration of imperfections and methods of checking the results are outlined.

• Quasi-Static Simulations using Implicit LS-DYNA ®

  Satish Pathy (LSTC), Thomas Borrvall (DYNAmore Nordic AB)

  Quasi-static tests that are part of the federal regulations such as FMVSS 216[1] and FMVSS 207/210[1] is predominantly simulated using LS-DYNA’s explicit solver. To be able to produce results in a reasonable time, mass-scaling and time-scaling are employed for these simulations, thereby the physics of the problem gets compromised. This paper demonstrates LS-DYNA’s Implicit capabilities to solve quasi-static problems in a reasonable amount of time, without compromising physics. Recent development and improvements to the implicit solver enables us to solve problems such as this, accurately and with a run turn-around time that is inside the reactionary period of the design community. Two popular tests – Roof-Crush and Seat-Pull tests were chosen for this exercise.

• Quicker Process to Consider Strain Hardening for Crash Analysis Using HYCRASH

  Sayaka ENDOH, Takahiko MIYACHI, Yasuyoshi UMEZU - JSOL Corporation

  As one of the important issues in correlation of crash analysis, we know that the press-forming effect has large influence for the result of the analysis. Some tries and studies were carried out to assume the forming result to the crash analysis. However these actions haven’t spread to the actual product development because of some difficulties. We mark the Inverse Solver to solve this issue and have developed the new solver HYCRASH, which can calculate the plastic strain and thickness distribution from the final shape of the product. We would like to represent two things in this study. First, the hardening effect plays an important role in the crash energy absorption. Second, HYCRASH can consider this correlation factor much easier and faster than the usual press simulation technique.

• Quicker Process to Consider Strain Hardening for Crash Analysis Using HYCRASH

  Sayaka ENDOH, Takahiko MIYACHI, Yasuyoshi UMEZU - JSOL Corporation

  As one of the important issues in correlation of crash analysis, we know that the press-forming effect has large influence for the result of the analysis. Some tries and studies were carried out to assume the forming result to the crash analysis. However these actions haven’t spread to the actual product development because of some difficulties. We mark the Inverse Solver to solve this issue and have developed the new solver HYCRASH, which can calculate the plastic strain and thickness distribution from the final shape of the product. We would like to represent two things in this study. First, the hardening effect plays an important role in the crash energy absorption. Second, HYCRASH can consider this correlation factor much easier and faster than the usual press simulation technique.

• Raising the treasure of SPDMs – How data compression and automatized event detection support engineers

  D. Borsotto, V. Krishnappa, S. Müller, F. Natter, T. Roth, K. Schreiner, H. Talaat, C.-A. Thole, T. Weinert

  To cope up with the ever growing amount of simulation runs being performed, tools and techniques are needed to store the huge amount of simulation data and to make use of data being stored. While current Simulation Data Management systems allows managing and accessing datasets and would facilitate putting this into action for analysis, the demand on bandwidth and storage increases. Even with SPDMs, the users usually only had tools and time to make rather straight forward model to model comparisons, between current model versions and their immediate predecessors. To take analysis capabilities and model development a leap forward, it is necessary to also make use of whole model development branches to learn from the gathered simulation information. With the availability of such tools, the value of past simulation data increases.

• Ramp Wave Compression in a Copper Strip Line: Comparison Between MHD Numerical Simulations (LS-DYNA®) and Experimental Results (GEPI device)

  Gaël Le Blanc,Patrice LaPorte,Gilles Avrillaud, Paul Vincent - ITHPP, France, Pierre-Yves Chanal, Pierre-Louis Hereil - Centre d’Etudes de Gramat, France, Pierre L’eplattenier - LSTC, USA

  GEPI [3][4] is a pulsed power generator developed by ITHPP for Centre d’Etudes de Gramat (CEG) devoted to ramp wave (quasi isentropic) compression experiments in the 1 GPa to 100 GPa range and to non shocked high velocity flyer plate in the 0.1 km/s to 10 km/s range. The aim of this paper is to compare numerical simulation and experimental results on a 3D GEPI configuration. A coupled mechanical / thermal / electromagnetism simulation has been performed to validate the new LS-DYNA beta version, ls980, where the electromagnetism package has been implemented. The validation is realized by free surface velocity comparisons on a reference configuration [5]. The study is presented in three main steps. First, a validation of LS-DYNA is performed by comparison to an analytical model and to another electromagnetic solver modeling a basic configuration. In the second step, the GEPI configuration is described and experimental strip line free surface velocities are analyzed. Then LS-DYNA models are presented. The model validation is realized by free surface velocity comparisons between LS-DYNA and GEPI results. As the electromagnetism solver requires a lot of memory, in order to optimize the memory used as well as the CPU time, the electromagnetic domain is limited to the “launcher” with a thickness around 1 mm. The rest of the strip line is merged to the “launcher” and the mechanical solver only is used there. The last section of this study presents the optimization of the strip line geometry in order to improve the magnetic pressure homogeneity along this strip line.

• Randles Circuit Parameters Set Up for Battery Simulations in LS-DYNA®

  Sarah Bateau-Meyer, Pierre L’Eplattenier, Livermore Software Technology Corporation, Livermore, CA;, Jie Deng, Min Zhu, Chulheung Bae, Theodore Miller, Ford Motor Company, Research and Innovation Center, Dearborn, MI

  A multi physics model for battery abuse was recently introduced in LS-DYNA. This model predicts coupled mechanical, thermal, electrical and electro-chemical responses. The complex electro-chemical behavior is described by simple equivalent circuits, called “Randles” circuits. Each Randles circuit connects two vis-à-vis nodes of the positive and negative current collector layers and consists in a State-Of-Charge (SOC) dependent voltage source, an internal resistance and a resistance-capacitance (RC) loop. The choice of the values of the circuit components in the LS-DYNA cards is let to the user and strongly depends on the battery cell. This paper thus proposes a procedure to choose with precision the Randles circuit components values from simple voltage and current measurements on the cell. The parametrization process is done by a parameter identification on these experimental coupled voltage/current measurements, such as Hybrid Pulse Power Characterization (HPPC) test results, in a single Randles circuit, representing the whole cell. The paper will present briefly the distributed Randles circuit model and the experimental tests before exposing one parameter identification method.

• Random Vibration Analysis for a Gunner Platform Frame using Experimental Data

  S. E. Yılmaz (FNSS Savunma Sistemleri)

  Remote controlled weapon systems have gained great importance in defense industry as they maximize crew safety with accurate shooting capabilities. On the other hand, vibration levels are of great consideration because of its effect on crew comfort and system reliability especially for tracked armored vehicles. In this study, vibrational evaluation is performed for a remote control gunner platform frame, which is mounted to the top plate of an armored tracked vehicle. Vibrational response of the gunner platform is critical for a successful completion of especially mobile missions. In order to perform random vibration fatigue evaluation, the experimental data obtained from the top plate of an armored tracked vehicle is used and random vibration analysis are performed using LS-DYNA®. Power Spectral Density (PSD) profiles provided in NATO AECTP 400 document are also included in the random vibration analysis with a degree of modification in order to make a comparison. Finally, random vibration analysis results from LS-DYNA® are compared with the results of another commercial software using similar analysis parameters.

• Random Vibration Fatigue Analysis Model Development from Explicit to Implicit in LS-DYNA®

  Hwawon Lee, Parvath Police (General Motors), Amit Nair (LSTC)

  Fatigue damage evaluation on vehicle body and hang-on components is one of the most critical paths for the vehicle development stage. Conventionally, fatigue analysis model has been characterized by linear static or dynamic model in which non-linearity of material and contact among vehicle parts are not properly considered, whereas the crash model using Explicit code takes both factors into account. Recent trend of crash event modeling is to increase number of elements up to several millions of finite elements, which is aided by rapidly improving computing power, enabling full vehicle simulations in a very short period of turnaround time. Currently, more focus is on the automotive industry to create larger FE models in a shorter period of time. This is to minimize or reduce vehicle development time caused by the size of the fatigue evaluation model. There were certain efforts to reduce modeling time by converting Explicit crash model to Implicit fatigue evaluation model without losing model contents in a very short period time. This improvement can be achieved in LS-DYNA. This paper demonstrates how to build random vibration fatigue analysis models on MAST (Multi Axis Shaking Table) from Explicit crash model and how to predict fatigue life under random vibration cyclic loading. The first model is a full pick-up truck box, and the other one is a simplified end-gate hinge. A series of parameter study has been attempted to achieve a good correlation between the simplified fatigue testing and such parameters including mesh size, shell element formulation, number of thru thickness integration point & forming effect. The most critical parameter affecting damage ratio in the pick-up truck box is identified by comparing the corresponding test and the proposed model to achieve reasonable fatigue life predictions.

• Random Vibration Fatigue Analysis with LS-DYNA

  A. Ringeval (CIMES), Y. Huang (LSTC)

  Fatigue damage assessment for components under random cyclic loading is an important concern in engineering. A new feature of random vibration fatigue analysis has been implemented to LS-DYNA, to perform the structural fatigue analysis in a random vibration environment. This feature computes cumulative damage ratio and expected fatigue life for structures, based on the Palmgren-Miner’s rule of cumulative damage ratio and material’s S-N fatigue curve. A series of fatigue analysis methods have been implemented. They include the Steinberg’s three band method, Dirlik method, Narrow band method, Wirsching method, Chaudhury and Dover method, Tunna method and Hancock method. Brief introduction of the analysis methods is provided. To facilitate post-processing of the fatigue analysis, a new binary plot file d3ftg has been implemented in LS-DYNA. This binary plot file provides fatigue analysis information including cumulative damage ratio, expected life, zero- crossing frequency, peak-crossing frequency and irregularity factor for the structure, based on the stress index adopted in the analysis and the load period. This file is accessible to LS-PREPOST. Several examples are given to demonstrate the effectiveness of the random vibration fatigue analysis feature with LS-DYNA. Some preliminary discussions on the different fatigue analysis methods are included.

• Random Vibration Fatigue Life Simulation of Bolt-on Metal Brackets using LS-DYNA®

  Jong S. Park, Ramakrishna Dospati, Ye-Chen Pan, General Motors;, Amit Nair, Livermore Software Technology Corporation

  Prediction of Vibration Fatigue Life is an important milestone during product design and development of Vehicle Brackets. Bracket in Vehicle is defined as a simple structure fastened to foundation structure or other brackets supporting mass of various modules. CAE simulation for Fatigue Life prediction gives useful information early in design cycle, and saves considerable time and cost compared with physical Shaker Table tests. LS-DYNA Implicit Simulation technology for Random Vibration Fatigue Life of Bolt-on Metal Bracket is developed. The simulation provides flexibility to evaluate multiple design options and accommodate design changes early in production development cycle. Bolt Fastening is included in the Simulation Process and the Fastening Stress is assumed to be maintained as the pre-stress for the assessment of Vibration Fatigue Life. This Fastening Stress is often very high and results in significant effect on Fatigue Life. Random loading is provided via the Power Spectral Density (PSD), which describes excitation acceleration levels in the frequency domain. System response to unit excitation is calculated using LS-DYNA’s steady state dynamics analysis. This analytical stress FRF and random loadings are then combined to calculate the stress response PSD, which is cycle-counted and used for the calculation of Fatigue Life.

• Rapid Development of Multiple Fold Patterns for Airbag Simulation in LS-DYNA Using Oasys Primer

  Miles Thornton, Richard Sturt, Anastasia Kalabina - Arup

  The creation of folded meshes for airbag deployment simulations is a time consuming task. The fold pattern has a significant effect on the speed and shape of deployment of the airbag, and therefore should be modelled when prediction of deployment timing is required, as is the case with out of position analysis for FMVSS 208. To investigate changes in fold patterns or airbag shape involves repeating the entire airbag mesh process for each modification. This paper describes a new mesh-independent folding tool in Oasys Primer that can speed up the modelling process. The time required for each operation is quantified for a variety of fold patterns on a thorax bag. Finally, a driver airbag is inflated using LS-DYNA’s ALE gas flow capability, and the deployment timing compared between mechanical and traditional zig-zag fold patterns.

• Rapid Simulations of Welding and AM using LS-DYNA® and LS-PrePost®

  Mikael Schill, Anders Jernberg, Anders Bernhardsson, DYNAmore Nordic AB, Linköping, Sweden;

  Simulation of the welding process in LS-DYNA has been continuously improving the recent years. The functionality in terms of solvers, materials, heat source and preprocessing GUI have been continuously expanded. One of the issues that remains to be solved is the sometimes quite long simulation times. The solution time of a welding simulation depends largely on the length and speed of the weld. This is especially true in Additive Manufacturing (AM) applications where the length of the weld can be very long. To remedy this problem, a dumping methodology is presented. The methodology still uses a thermo-mechanical approach, but the weld energy is dumped in the complete weld rather than applied incrementally. This paper presents the methodology in detail together with examples and comparisons in both welding and AM applications.

• Rate Dependent Progressive Composite Damage Modeling using MAT162 in LS-DYNA®

  Bazle Z. (Gama) Haque, John W. Gillespie Jr. (University of Delaware)

  Performing experiments in numerical space and predicting accurate results are the main research focus of many computational mechanicians. These goals may in general sound challenging, however, makes perfect sense in cases where experiments are not possible, e.g., landing on Mars, sea waves impacting marine structures, crash landing of space shuttle, etc. Composite damage modeling plays a vital role in designing composite structures for damage tolerance, energy dissipating crash, impact, ballistic, and blast applications. A progressive composite damage model MAT162 is developed by Materials Sciences Corporation and further modified by the authors and implemented in explicit finite element analysis code LS-DYNA. A total of thirty-four material properties and parameters are required to define such a material model. Besides the ASTM standard test methods for determining the elastic and strength properties, the authors have developed a low velocity impact methodology in determining the rate insensitive model parameters. Recently, model validations with depth of penetration and ballistic experiments have been performed to determine the rate sensitive model parameters. These validated model parameters are used to predict composite damage and resistance behavior of composite structures made from plain-weave plain weave S-2 glass/SC15 composites under quasi-static, low velocity impact and crush, ballistic, and blast loading conditions. Analysis procedure and results of these numerical experiments will be presented.

• Re-Using Crash Models for Static Load Cases with Minimal Effort

  Anders Jonsson, DYNAmore Nordic AB

  To demonstrate the implicit capabilities in LS-DYNA®, some examples of load cases typical for automotive applications are presented. A public FE-model of a mid-size passenger car (including interior, tires, suspension, exhaust system etc.) originally intended for explicit road-side safety analyses was, by minimal modifications, converted for implicit analyses. Some recommendations on how to go from an explicit (crash) model to an implicit model for static load cases are given. Results from some typical durability load cases are presented, like door sag, door slam and hood/fender loading. Also, a frequency domain analysis of the transfer functions between the suspension and the front seat attachments points was performed.

• Real Time Biofidelic positioning of Human Models with ANSA

  L. Rorris, A. Lioras (BETA CAE Systems)

  The use of Human Body Models, for safety simulations, in the automotive industry, has not been widespread for various reasons. One was that the specific models had not reached expected sophistication levels as they are mainly used in the research phase and not in production. Nevertheless, from their first introduction in late nineties until now, a lot of development and research effort has been invested. The parallel growth in computational power during the same period resulted in much more complex and realistic models that can cover the needs of the occupant safety engineering community.

• Realistic articulation, positioning and simulation of Human Body Models using Oasys LS-DYNA tools

  Manu Agarwal, Galal Mohamed

  The application of human body models (HBMs) in numerical simulation offers exciting opportunities in automotive development in areas such as comfort, ergonomics, and safety. These models are used to simulate human body kinematics and injury responses and risks in a variety of simulated impact scenarios. The industry leading THUMS and GHBMC family of models are usually provided in two standard postures – occupant and pedestrian. The occupant posture is typically a driving posture in an up-right position, whereas the pedestrian is a walking posture with fixed arm and leg angles. These standard postures are limiting and do not reflect the diversity of postures which an occupant or pedestrian can assume at the point of a collision. Furthermore, current trends in vehicle automation are also expected to give rise to new seating postures such as forward or backward facing reclined seats. A major challenge for users, however, is that these models are not provided with pre-configured information to aid positioning making it a very difficult and time-consuming effort.

• Realistic Stochastic Virtual Microstructure Generation for Woven Fabrics and Textile Composites: The Thermal Growth Approach

  Gaurav Nilakantan, Teledyne Scientific & Imaging, Thousand Oaks, CA 91360, USA

  Generating realistic 3D yarn-level finite element models of textile weaves and impregnated textile composites poses a challenge because of the complexity of the 3D architecture and the need for achieving high quality finite elements and non-intersecting yarn volumes. A common approach is to sweep a constant yarn cross-sectional shape along a smooth and continuous centerline that repeats over a unit cell length. This approach breaks down with tight and complex weave architectures. Moreover, actual microstructures of dry fabrics and textile composites are often aperiodic and non-deterministic. In this work, a new method to generate realistic virtual microstructures of woven fabrics and textile composites using a “thermal growth” approach is presented. This involves a series of mechanics-driven orthotropic volumetric expansions and shrinkages of the yarn cross-sections and centerlines that are artificially induced by prescribed thermal loads, along with mechanics-driven yarn deformations in order to “grow” or “form” the yarns into their final realistic configurations within the weave. Contact-pairs are defined between interlacing yarn surfaces to prevent yarn inter-penetrations. The final virtual microstructures are generated through a series of finite element simulations executed using LS-DYNA®. This process is demonstrated by considering the case study of a plain-weave Kevlar fabric (Style 706) used in body armor. A movie of the thermal growth process in action is available through the YouTube URL provided. The virtual microstructures are characterized using ImageJ-based image analysis and then validated against experimental microstructures. Relatively fine microstructural features are accurately reproduced. The process is amenable to any textile weave architecture including 2D, 2.5D, and 3D woven, braided, and knit architectures.

• Reasons for Scatter in Crash Simulation Results

  Clemens-August Thole, Liquan Mei - Fraunhofer Institute for Algorithms and Scientific Computing

  In crash simulation, small changes of the model or boundary conditions may result in substantial changes of the simulation results. For a BMW car model, the node positions of the crashed model show differences of up to 14 cm between several executions on a parallel machine for the same input deck. For the Dodge Neon testcase, small variations of the barrier position result in substantial scatter of the intrusion. Detailed investigations of several models have shown, that in some cases numerical effects might be responsible for the scatter in the results. In most cases, however, the instable behaviour of the simulation results is caused by bifurcations. These bifurcations result from numerical algorithms or are a feature of the car design. In the Neon model the scatter is a result of the interaction between the axle and the engine block. In the case of the BMW car model, the scattering of the simulation results is a direct consequence of buckling of the longitudinal rail. A slight redesign of this part causes stable results for parallel machines. Stable crash behaviour of a car model is a design target for the following reasons: • Simulation results might be misleading, when the impact of changes of the model or model parameters is investigated. • The numerical model is always only an idealized representation of the real car design. A stable crash behaviour simplifies the prediction of the crash behaviour of the real car from simulation results for the idealized model. • Smaller bounds for the scattering of the characteristic crash values will improve the possibilities of the engineer to find the best compromise for the car design with respect to the targets of the different load cases. Due to the nature of crash simulation many parts might show instable behaviour. Usually, only a small subset has a real impact on those values, which measure the crash behaviour (like intrusion). Measuring the scatter of simulation results for these characteristic values is a first step. In order to improve the design, it is necessary to trace this scatter back to its origin in space and time. DIFFCRASH is a tool, which allows one to measure scatter and to trace this scatter back to its origin. It allows the engineer, to understand the mechanisms of propagation and amplification of scatter during the crash itself as a basis for the improvement of the stability of the car design.

• Recent advancements in LS-DYNA Pre-processing for Crash Simulation

  Lambros Rorris, Athanasios Lioras, Yianni Kolokythas (BETA CAE Systems SA)

  The increasingly demanding and complex requirements in Crash Analysis, call for continuous and innovative software development. BETA CAE Systems in an effort to meet and exceed the requirements of the industry is introducing new cutting edge technologies, in the pre-processing area with ANSA. This paper presents these new technologies. As CAE comes to maturity the challenges and requirements for the CAE preprocessing software also evolve. Preprocessing should not be a manual job anymore. Automated processes and data handling is crucial for solving complex real world problems. In the area of Crash and Safety analysis we can find many such examples. FMVSS 201 226, and EURO NCAP pedestrian testing protocols demand highly specialized tools that can perform complex positioning operations that until now could only be done manually. With the introduction of the newer ANSA versions, all these operations can be performed, by the software, in a totally automated way. Automating such procedures leads to the next step. This is performing robustness and sensitivity analyses to gain confidence of the analysis results and deeper understanding of the designs and models. The advanced scripting environment along with the pre and post processing facilities provided by our products has been used to demonstrate such a use.

• Recent advances in THUMS : development of individual internal organs, brain, small female, and pedestrian model

  Masami Iwamoto, Kiyoshi Omori, Hideyuki Kimpara, Yuko Nakahira, Atsutaka Tamura, Isao Watanabe, Kazuo Miki - Toyota Central R&D Labs., Inc.,, Junji Hasegawa - Toyota Motor Corporation, Fuminori Oshita - The Japan Research Institute, Ltd.

  A finite element model of total human model for safety, which is called THUMS, has been developed in order to study human body responses for impact loads. In previous report, a mid-size adult male occupant model of THUMS was developed and validated for several impact loads. This paper briefly describes recent advances in THUMS. Individual internal organ models and a detailed brain model have been developed to be integrated with the occupant model. In addition to the mid-size male occupant model, a small female occupant model and a mid-size male pedestrian model have been also developed and validated in order to simulate impact responses of female occupants and male pedestrians.

• Recent Advances on Higher Order 27-node Hexahedral Element in LS-DYNA ®

  Hailong Teng (LSTC)

  This paper presents recent advances of second-order hexahedral element developed for explicit/implicit analysis in LS-DYNA. Several benchmark problems are studied to demonstrate the performance of the higher order element. The results obtained in modeling practical applications involving large deformations, nearly incompressible materials, severe distortions, bending, and contact-impact are also encouraging. Compared to standard 8-node brick element, the high order element is computationally expensive, but it is found to be competitive with other element types due to its much higher accuracy and higher convergence rate. Furthermore, high order element naturally contains the linear strain field and is capable of modeling bending and curved shape accurately without using either hourglass control or introducing incompatible modes. From a user viewpoint, what is gained is versatility in modeling a wide variety of geometries including three-dimensional or plate/shell geometries, and simplicity since only displacement degrees of freedom are used. This paper also present two techniques that transfer 8-node hexahedral model to higher order hexahedral model.

• Recent Advances on Surrogate Modeling for Robustness Assessment of Structures with Respect to Crashworthiness Requirements

  Prof. F. Duddeck, E. Wehrle (Technical University Munich)

  Due to the inherent nonlinearity, crashworthiness is one of the most demanding design cases for vehicle structures. Recent developments have enabled very accurate numerical simulations and corresponding optimizations. Therefore, structural concepts are now much better adapted to the specific requirements. This has led to designs in which redundancies are reduced and highly effective car concepts have been derived.

• Recent and Future Developments for the ICFD Solver in LS-DYNA

  F. Del Pin, I. Caldichoury, R. R. Paz, C. Huang (LSTC)

  Since its release in R7 the Incompressible CFD solver (ICFD) has been rapidly improving and increasing its functionality. In this paper a summary of the latest and current developments will be presented. The focus will be on four topics. First the steady state solver and its coupling capabilities for fluid-structure interaction (FSI) or conjugate heat transfer (CHT) will be presented. In second place the recent modifications to the boundary layer mesh generation will be introduced where some default parameters have changed. The possible implications of these changes in the solution will be mentioned. Third a short introduction to coupling ICFD with LS-OPT for shape optimization will be presented. The idea is to use ANSA to morph the surface mesh driven by LS-OPT to provide an optimal solution. Finally some of the current developments will be enumerated like immersed interfaces, periodic boundary conditions, porous media through shell elements for parachute simulation, etc. These developments will be part of future LS-Dyna releases.

• Recent Development for Metal Forming Simulation

  Yasuyoshi Umezu, Ninshu Ma - The Japan Research Institute, Ltd., Japan

  Since 1996, Japan Research Institute Limited (JRI) has been providing a sheet metal forming simulation system called JSTAMP-Works packaged the FEM solvers of LS-DYNA and JOH/NIKE3D, which might be the first multistage system at that time and has been enjoying good reputation among users in Japan. To match the recent needs, “faster, more accurate and easier”, of process designers and CAE engineers, a new metal forming simulation system JSTAMP-Works/NV is developed. The JSTAMP-Works/NV packaged the CAD automatic healing function in it and had much more new capabilities such as prediction of 3D trimming lines for flanging or hemming, remote control of solver execution for multi-stage forming processes and shape evaluation between FEM and CAD. On the other way, a multi-stage multi-purpose inverse FEM solver HYSTAMP is developed and will be soon put into market, which is approved to be very fast, quite accurate and robust. Lastly, authors will give some application examples of user defined ductile damage subroutine in LS-DYNA for the estimation of material failure and springback in metal forming simulation.

• Recent development in Ansys LS-DYNA’s NVH solvers

  Yun Huang, Tom Littlewood, Zhe Cui, Ushnish Basu

  LS-DYNA has been used in automotive industries for many years, especially in vehicle crashworthi-ness and occupant safety analysis areas. Besides that, LS-DYNA also provides many useful features for NVH (Noise, Vibration and Harshness) analysis. During the past few years, based on the feedback and suggestions from users, many updates and enhancements in the NVH solvers have been imple-mented, including - Fast FRF analysis with reduced eigenvectors. - Frequency dependent adaptive remeshing for BEM acoustics. - Frequency interpolation for BEM acoustic solvers. - Fluid added mass computation and its application in modal and vibration analysis. - Coupling of acoustic spectral element method and piezoelectric materials for ultrasonic sensor simulation. - Enhanced d3max output. - New options in fatigue solvers. - Other enhancements.

• Recent Development of ICFD Pre and Post Processing in LS-PrePost ®

  Yu Wenhui, Zhang Zhanqun (Dalian Fukun Technology Corporation (China)), Philip W HO, Inaki Çaldichoury (LSTC)

  As the usage of ICFD module of LS-DYNA grow widely, the requirements of Pre and Post processing dedicated to LS-DYNA ICFD module become more and more urgent. Since early 2014, we’ve been working on ICFD post processing module in LS-PrePost with LS-DYNA developers. It’s now available in LS-PrePost in version 4.3. This new ICFD post processing module is object-oriented, works in both 2D and 3D case. Currently, following functions are included: Section Plane(line), ISO Surface (curve), Stream Line, Vector Plot, Level Set, Data Extraction(Point, Line), Line Integral Convolution(LIC), Attached/Separated Line, Vertex Core. The Pre Processing module of LS-DYNA ICFD module is also under design and development, aims to help traditional ICFD users transfer to LSDYNA ICFD application easily.

• Recent Development of LS-DYNA® XFEM Shells for Dynamic Ductile Failure Analysis: XFEM with GISSMO Damage Model

  Y. Guo, C. T. Wu (Livermore Software Technology (LST), an ANSYS company)

  This paper presents a coupling of LS-DYNA XFEM shell method [30] and GISSMO damage model for dynamic ductile failure in shell structures. The XFEM shell formulation adopts the finite element continuous-discontinuous approach with the phantom-node technique [17] employed to incorporate velocity discontinuities in standard shell finite element formulations. The generalized incremental stress-state dependent damage model (GISSMO) adds damage and failure to most material models in LS-DYNA that do not allow failure. With the stress-triaxiality dependent failure criterion provided in GISSMO model, XFEM can better simulate material failure and crack propagation in mixed modes and under more complicated loading conditions. The option of element-size dependent regularization factor in GISSMO model removes the strain localization existing in the standard continuum damage model and suppresses the element-size sensitivity of ductile fracture, which is similar to the regularization zone approach in our original XFEM shell method for ductile fracture [30-32]. Unlike element erosion, when an element fails after certain number of integration points reach failure criterion, a crack (discontinuity)is inserted into the element with its direction depending on the stress state or other propagation option, and the element becomes an XFEM element comprised of two phantom elements. XFEM formulation allows crack propagation across elements without the sensitivity on mesh discretization and maintains the conservations of mass and momentum. Several numerical benchmarks and examples are tested using the explicit dynamics analysis to demonstrate the effectiveness and accuracy of the method described in this paper.

• Recent Developments and Roadmap Part 5: ALE, DEM, SPH, Particle

  Dr. Jason Wang (LSTC)

  Recent Developments: ALE, DEM, SPH, Particle

• Recent Developments and Roadmap Part 1: LS-PrePost

  Mr. Philip Ho (LSTC)

  Recent Developments: LS-PrePost

• Recent Developments and Roadmap Part 2: Dummy Models

  Dr. Christoph Maurath (LSTC)

  Recent Developments: Dummy Models

• Recent Developments and Roadmap Part 4: Electromagnetics

  Dr. Pierre L’Eplattenier (LSTC)

  Recent Developments: Electromagnetics

• Recent Developments and Roadmap - Conclusions

  Dr. John O. Hallquist (LSTC)

  Conclusions

• Recent Developments and Roadmap Part 3: Incompressible CFD

  Dr. Facundo Del Pin (LSTC)

  Recent Developments: Incompressible CFD

• Recent Developments and Roadmap Part 0: Introduction

  Dr. John O. Hallquist (LSTC)

  Introduction

• Recent Developments for Frequency Domain Analysis in LS-DYNA

  Y. Huang, Z. Cui (LSTC)

  Since the 971 R6 version, a series of frequency domain features have been implemented to LS-DYNA. They include FRF, SSD, random vibration, acoustics, response spectrum analysis and fatigue analysis. With the implementation of these features, the application of LS-DYNA is extended to the new area of frequency domain analysis. Some new developments and updates have been made for the frequency domain features, since the last European LS-DYNA Users’ Conference in 2015. The main developments and updates include - ERP (equivalent radiated power) computation based on SSD - Direct SSD solver - Incorporation of phase difference in cross PSD in random vibration analysis - new ASCII and binary databases for post-processing of the frequency domain analysis results - Incorporation of phase difference in cross PSD in random vibration analysis - Incorporation of rotational dof in excitation and response in FRF and SSD ... - And others These new developments and updates were made to meet the requirements from users, and to enhance the capabilities of frequency domain analysis in LS-DYNA. This paper provides a review on these new developments and updates.

• Recent Developments for Thermo-Mechanically Coupled Simulations in LS-DYNA with Focus on Welding Processes

  T. Klöppel (DYNAmore), T. Loose (Ingenieurbüro Tobias Loose)

  With increased mechanical and functional requirements put on many parts produced by the manufacturing industry, the numerical simulation of the process has gained importance within the last years. The main objective when applying numerical tools is an accurate prediction of the finished geometry. In order to allow for an efficient optimization procedure in the design phase of the process the complete manufacturing process chain has to be included in the simulation. For many processes in sheet metal forming this is state of the art.

• Recent Developments for Welding Simulations in LS-DYNA ® and LS-PrePost ®

  Mikael Schill, Anders Jernberg (DYNAmore Nordic AB), Thomas Klöppel (DYNAmore GmbH)

  The multi-physics capabilities of LS-DYNA makes it ideal for simulating the welding process where the mechanical and thermal physical regimes are combined to simulate the resulting part tolerance and residual stresses. Welding capabilities are continuously being added to LS-DYNA, e.g. the material models *MAT_CWM and *MAT_CWM_THERMAL which are tailored for CWM simulations. The CWM material models include e.g. ghost element and anneal functionality. However, the challenge when performing this type of simulations is not only related to the solver. The pre-processing quickly becomes a daunting task where the user needs to assign weld paths, weld power and clamping for several weld passes. To accommodate for this, a novel welding GUI has been added to LS-PrePost. The GUI includes e.g. a welding process planner, welding path selection using the graphical interface and welding heat source definition and visualization. Further, the welding process setup is written to an ASCII input file that can be combined with an optimizati on software to optimize the process with respect to e.g. welding deformations. This paper will present the recent developments in the mechanical and thermal solvers in LS-DYNA to accommodate for welding simulations. Also, the novel Welding GUI in LS-PrePost will be presented together with some application examples.

• Recent Developments in *DEFINE_PRESSURE_TUBE for Simulating Pressure Tube Sensors in Pedestrian Crash

  Jesper Karlsson, DYNAmore Nordic

  This paper presents recent developments of the new keyword *DEFINE_PRESSURE_TUBE, designed to efficiently simulate pressure waves in thin air-filled tubes. The primary application is a new crash detection system for pedestrian impact, where a thin air-filled tube is embedded in the front bumper and fitted with pressure sensors at the ends. On impact, the tube is compressed and a pressure wave travels to the sensors, enabling localization and extent of the impact. In recent years, such systems have gained popularity in the automotive industry, posing a challenging task in efficient and accurate simulations.

• Recent Developments in Isogeometric Analysis for LS-DYNA®

  David Benson, Attila Nagy, Liping Li, LSTC, Livermore, CA, USA;, Stefan Hartmann, Dynamore GmbH

  Isogeometric analysis (IGA) uses the spline functions from CAD (computer-aided design) for analysis with the objectives of 1) reducing the effort of moving from design to analysis, 2) using the actual geometry of the parts from CAD instead of approximating them with polynomials, and 3) obtaining higher order accuracy through the higher order basis functions of CAD. LS-DYNA is the first commercial code to support IGA through the implementation of generalized elements, and then through key word descriptions of patches of B-spline and NURBS elements. Three shell formulations and a solid element formulation are currently available. Additional recently added capabilities, including improved contact, anisotropic material modeling, spotweld models and support for unstructured spline capabilities through the specification of their Bezier extractions. These and other recent additions are described and demonstrated. In addition, some of the difficulties industry has encountered in moving to this new technology are discussed.

• Recent Developments in Isogeometric Analysis with Solid Elements in LS-DYNA®

  Liping Li, David Benson, Attila Nagy, Livermore Software Technology Corporation, Livermore, CA, USA;, Mattia Montanari Nik Petrinic, Department of Engineering Science, University of Oxford Parks Road, OX1 3PJ, Oxford, UK;, Stefan Hartmann, Dynamore GmbH, Stuttgart, Germany

  Isogeometric analysis (IGA), which uses the same geometry from CAD (computer-aided design) for numerical analysis, has been studied more and more in the past few years. The continuous development of IGA with shell and solid element has been added to LS-DYNA. Many of the standard analysis capabilities in LS-DYNA are now available for IGA such as explicit and implicit analysis. In this paper, we will provide updates on IGA: dynamics analysis using IGA solid, the implementation of user defined material including anisotropic material modeling and support for unstructured Spline capabilities through their Bézier extractions.

• Recent Developments in JSTAMP/NV for the Best Stamping Simulation Environment

  Yuji Kato, Yasuyoshi Umezu, Yuko Watanabe - JSOL Corporation

  In recent years, expectations for stamping simulation systems have increased in stamping die design process, as the needs for lightweight products and short production lead time have grown. Aiming at the best stamping simulation environment, JSOL Corporation has been developing JSTAMP/NV since 1996. One of the most competitive advantages of JSTAMP/NV is accurate prediction of deformation and formability by explicit and implicit solutions in LS-DYNA®. JSTAMP/NV also incorporates the implicit solver JOH/NIKE and the one-step inverse solver HYSTAMP developed by JSOL Corporation. This integrated system has been enjoying a good reputation in stamping die industry, especially Japanese automotive, appliance, and electronics manufactures and their suppliers. The recent needs towards stamping simulation software can be classified as: accurate results and their evaluation, short computation times, easy-to-use features for iterative process improvement, and support for modern stamping technologies. JSTAMP/NV continues to evolve to meet such requirements. In this paper, we present the recent developments in JSTAMP/NV, including ironing analysis support using solid elements, Yoshida-Uemori model material database, advanced trimmed mesh, enhanced springback compensation, easy-to-start reanalysis feature, free 3D viewer for collaboration, and hot stamping analysis capability.

• Recent Developments in LS-DYNA – Part I

  J.O. Hallquist, B. Wainscott and other developers (LSTC)

• Recent Developments in LS-DYNA for Civil Engineering

  Brian Walker - ARUP

  • LS-DYNA has well-known applications for earthquake and blast/impact engineering – Building design development – Site response studies – Development of isolators and energy absorbers • Arup have recently added new features: – Damping model for vibration studies – Material model - Rock and general Mohr-Coulomb – Staged construction – Pore water pressure analysis • This paper will show some applications of the new features

• Recent Developments in LS-DYNA

  Dr. John Hallquist - LSTC

  In this presentation Dr. John O. Hallquist, founder and president of Livermore Software Technology Corporation (LSTC), will give an overview about recent developments in LS-DYNA. LS-DYNA is a highly advanced general-purpose nonlinear finite element program that is capable of simulating complex real world problems. The distributed memory solver provides very short turnaround times on Unix, Linux and Windows clusters. The major development goal of LSTC is to provide within LS-DYNA capabilities to seamlessly solve problems that require • "MULTI-PHYSICS", • "MULTIPLE STAGES", • "MULTI-PROCESSING". Its fully automated contact analysis capabilities and error-checking features have enabled users worldwide to solve successfully many complex crash and forming problems. LSTC develops sophisticated tools for modeling and simulating the large deformation behavior of structures. In addition to LS-DYNA the tools LS-PREPOST for pre - and post-processing, and LS-OPT for optimization are developed by LSTC. The main applications are: • Large Deformation Dynamics and complex Contact Simulations • Crashworthiness Simulation • Occupant Safety Systems • Metal Forming • Explicit/ Implicit Analysis • Metal, Glass, and Plastics Forming • Multi-physics Coupling • Failure Analysis • Sophisticated Material Models • Fluid-Structure Interaction • SPH (Smooth Particle Hydrodynamics) • EFG (Element Free Galerkin) LSTC was founded in 1987 by John O. Hallquist to commercialize as LS-DYNA the public domain code that originated as DYNA3D. DYNA3D was developed at the Lawrence Livermore National Laboratory, by LSTC’s founder, John O. Hallquist.

• Recent Developments in LS-DYNA

  Dr. John Hallquist - LSTC

  In this presentation Dr. John O. Hallquist, founder and president of Livermore Software Technology Corporation (LSTC), will give an overview about recent developments in LS-DYNA. LS-DYNA is a highly advanced general-purpose nonlinear finite element program that is capable of simulating complex real world problems. The distributed memory solver provides very short turnaround times on Unix, Linux and Windows clusters. The major development goal of LSTC is to provide within LS-DYNA capabilities to seamlessly solve problems that require • "MULTI-PHYSICS", • "MULTIPLE STAGES", • "MULTI-PROCESSING". Its fully automated contact analysis capabilities and error-checking features have enabled users worldwide to solve successfully many complex crash and forming problems. LSTC develops sophisticated tools for modeling and simulating the large deformation behavior of structures. In addition to LS-DYNA the tools LS-PREPOST for pre - and post-processing, and LS-OPT for optimization are developed by LSTC. The main applications are: • Large Deformation Dynamics and complex Contact Simulations • Crashworthiness Simulation • Occupant Safety Systems • Metal Forming • Explicit/ Implicit Analysis • Metal, Glass, and Plastics Forming • Multi-physics Coupling • Failure Analysis • Sophisticated Material Models • Fluid-Structure Interaction • SPH (Smooth Particle Hydrodynamics) • EFG (Element Free Galerkin) LSTC was founded in 1987 by John O. Hallquist to commercialize as LS-DYNA the public domain code that originated as DYNA3D. DYNA3D was developed at the Lawrence Livermore National Laboratory, by LSTC’s founder, John O. Hallquist.

• Recent Developments in LS-DYNA® S-ALE

  Hao Chen (Ansys Livermore)

  The LS-DYNA ALE/FSI package is widely used in studying structures under blast loading. Generally, the ALE mesh is necessarily unstructured to accommodate complex geometries; however, for simple rectilinear geometries, a structured, logically regular, mesh can be utilized. Recognition of this latter case leads to algorithmic simplifications, memory reductions, and performance enhancements, which are impossible in unstructured mesh geometries. In 2015, LS-DYNA introduced a new structured ALE (S-ALE) solver option dedicated to solve the subset of ALE problems where a structured mesh is appropriate. As expected, recognizing the logical regularity of the mesh brought a reduced simulation time for the case of identical structured and unstructured mesh definitions. In this paper we will introduce the new developments and enhancements in LS-DYNA S-ALE for the past two years.

• Recent Developments in LS-DYNA® S-ALE

  Hao Chen, Ian Do, Livermore Software Technology Corporation

  The LS-DYNA ALE/FSI package is widely used in studying structures under blast loading. Generally, the ALE mesh is necessarily unstructured to accommodate complex geometries; however, for simple rectilinear geometries, a structured, logically regular, mesh can be utilized. Recognition of this latter case leads to algorithmic simplifications, memory reductions, and performance enhancements, which are impossible in unstructured mesh geometries.

• Recent Developments in Material Testing for Characterization of Materials (Deformation and Failure) for LS-DYNA Materials Models

  Amos Gilat, and Jeremy D. Seidt (Ohio State University)

  Several new testing methods that have been recently developed for mechanical characterization (deformation and failure) of materials are presented. The data from these tests is used for the development and calibration of material models (constitutive relations) in LS-DYNA. The first method involves the use of Digital Image Correlation (DIC) in tests that are used for generating data needed for the MAT224 model. In these tests specimens with different geometries are loaded and DIC measurements are used for determining the equivalent failure strain as a function of stress triaxiality and Lode parameter. The second testing method is a shear test for sheet metals. The experiment is done by using a flat notched specimen in a tensile apparatus. The shear strain is measured by using DIC within and on the boundary of the notch. The third development is a dynamic punch test in which the deformation of the specimen is measured continuously with 3-D DIC. The fourth is a high strain rate tensile testing technique for Kevlar cloth and Kevlar yarn in a tensile Split Hopkinson Bar (SHB) apparatus. The Kevlar cloth/yarn is attached by specially designed adaptors that keep the impedance FRQVWDQW ,Q DGGLWLRQ WR WKH WUDGLWLRQDO PHWKRG RI GHWHUPLQLQJ WKH VSHFLPHQ¶V strain from the recorded waves in the bars the strain is also measured with DIC. The fifth development is an apparatus for testing at intermediate strain rates in compression. In this apparatus the specimen can be deformed at strain rates ranging from 20 s-1 to 200 s-1. The apparatus is a combination of hydraulic actuator and a long (40 m) transmitter bar. The stress in the specimen is determined from the stress wave and the strain and strain rate is determined by using DIC. The results show very clean (no ringing) stress strain curves.

• Recent Developments in Mechanical Characterization (Deformation and Failure) of Materials

  A. Gilat, J. D. Seidt (Ohio State University)

  Several new testing methods that have been recently developed for mechanical characterization (deformation and failure) of materials are presented. The data from these tests is used for the development and calibration of ®material models (constitutive relations) in LS-DYNA . The first method involves the use of Digital Image Correlation (DIC) in tests that are used for generating data needed for using the MAT224 model. In these test specimens with different geometries are loaded and DIC is used for measuring full field strains and relative displacements. The second testing configuration is a shear test for sheet metals. The experiment is done by using a flat notched specimen in a tensile apparatus. The shear strain is measured by using DIC within and on the boundary of the notch. The third development is a high strain rate tensile testing technique for Kevlar cloth and Kevlar yarn in a tensile Split Hopkinson Bar (SHB) apparatus. The Kevlar cloth/yarn is attached to the bars by specially designed adaptors that keep the impedance constant. In addition to the traditional method of determining the specimen’s stress and strain from the recorded waves in the bars the strain is also measured with DIC. The fourth development is an apparatus for testing at intermediate strain rates in compression. In this -1 -1apparatus the specimen can be deformed at strain rates ranging from 20 s to 200 s . The apparatus is a combination of hydraulic actuator and a compression SHB. The stress in the specimen is determined from the stress wave in a very long (40 m) transmitter bar and the strain and strain rate is determined by using DIC. The results show very clean (no ringing) stress strain curves.

• Recent developments in NVH and fatigue solvers in Ansys LS-DYNA®

  Y. Huang, T. Littlewood, Z. Cui, U. Basu (Ansys/LST), S. Hartmann (DYNAmore), D. Benson (Ansys/LST)

  As one of the mainstream software packages widely used in automotive industry, LS-DYNA provides not only strong nonlinear capabilities for crashworthiness simulation, but also a suite of solvers for NVH and fatigue (durability) analysis. For NVH analysis, a series of vibration and acoustic solvers have been implemented to meet the need from CAE analysis of automotive of different levels and phases. They include FRF (Frequency Response Function), SSD (Steady State Dynamics), random vibration, response spectrum analysis, and acoustic analysis based on BEM (Boundary Element Method), FEM (Finite Element Method) and SEM (Spectral Element Method). The fatigue analysis features include fatigue damage solvers in both time domain and frequency domain (based on random vibration and steady state vibration).

• Recent Developments in the Electromagnetic Module: A New 2D Axi-Symmetric EM Solver

  P. L‘Eplattenier, I. Çaldichoury (LSTC)

  An electromagnetism module has being developed in LS-DYNA for coupled mechanical/thermal/electromagnetic simulations. More recently, a new 2D axi-symmetric version of this solver was introduced, allowing much faster simulations. In this solver, the EM equations are solved in a 2D plane, and the 2D EM fields, Lorentz force and Joule heating are then expanded to 3D elements by rotations around the axis. This allows to couple the 2D EM with 3D mechanics and thermal, thus keeping all the LS-DYNA 3D capabilities available.

• Recent Developments in Time Domain Fatigue Analysis with LS-DYNA®

  Zhe Cui, Yun Huang (Livermore Software Technology, an ANSYS Company)

  A series of new options were implemented to the time domain fatigue analysis features since the last international LS-DYNA User’s Conference 2018. They include:  Fatigue mean stress correction methods  Load steps definition  Fatigue damage evolution  Fatigue failure simulation  Multiaxial fatigue analysis  Fatigue summation This paper gives a brief review of these new options for time domain fatigue analysis with LS-DYNA. Some examples are provided to demonstrate the new feature of LS-DYNA and show how to use this feature towards different loading cases.

• Recent Developments of LS-DYNA Performance Optimization

  Youn-Seo Roh, Henry Fong - Sun Microsystems, Inc.

  A recent effort of optimizing the performance of LS-DYNA running on SPARC(R)-SolarisTM servers is described. With new releases of compilers, generated executables benefit from the additional performance of latest UltraSPARC(R) CPU's for SMP servers. Also, new release of Sun HPC ClusterToolsTM cluster environment includes tools that facilitates tuning of LS-DYNA-MPP executables and the MPI environment. A collection of development tools targeted for SPARC performance improvement results in faster simulations, fully benefiting continuously updated hardware performance. Those developments are exhibited with customer benchmark examples. With Sun ONE Grid Engine products, more efficient simulation environment is viable for LS-DYNA simulation.

• Recent Developments of Smoothed Particle Galerkin (SPG) Method for Joint Modeling

  Youcai Wu, Wei Hu, Xiaofei Pan, C.T. Wu (Livermore Software Technology, an ANSYS company)

  This paper presents the most up-to-date status of SPG (Smoothed Particle Galerkin) development with a focus on the establishment of a failure criterion library, a default keyword parameter setting, and its application in joint modeling. In the recent years, SPG bond failure criterion has been extended from effective plastic strain to 1st/3rd principal strain, maximum shear strain, 1st principal stress and several other quantities defined through *MAT_ADD_EROSION (e.g. effective stress/strain and GISSMO damage). Meanwhile, to minimize users’ work in setting up an SPG simulation, default parameters have been provided so that user can set up the SPG material failure analysis easily with as few as one prescribed parameter for the failure criterion. To demonstrate the effectiveness of SPG method with the new features, the failure modeling of FDS (flow drill screwing) and spot welding is studied.

• Recent Developments of the EM-Module in LS-DYNA – A Discussion

  L. Kielhorn, T. Rüberg, J. Zechner (TAILSIT)

  Since 2017 TAILSIT has maintained a close collaboration with Ansys/LST, formerly LSTC. Our partnership focuses mainly on the enhancement of LS-DYNA's electromagnetic (EM) solver module which is based on a coupling between Finite Elements (FEM) and Boundary Element Methods (BEM). This approach makes the EM solver highly suited for multiphysics problems. Prominent examples are, e.g., the simulation of parts moved by electromagnetic forces as well as processes like metal forming, welding, and induction heating.

• Recent Developments of the EM-Module in LS-DYNA

  Lars Kielhorn, Thomas Rüberg, Jürgen Zechner

  Since 2017, TAILSIT maintains a close collaboration with Ansys/LST. Our partnership focuses on the enhancement of LS-DYNA's electromagnetic (EM) solver module which is based on a coupling between Finite Element (FEM) and Boundary Element Methods (BEM).

• Recent Enhancements and Studies of Isogeometric Shells in LS-DYNA

  Lukas Leidinger, Stefan Hartmann, Qining Tang, Philipp Bähr, Silke Sommer, Christian Ilg, Werner Feix, Filipe Andrade

  Isogeometric Analysis (IGA) [1] is a Finite Element Analysis (FEA) technology that uses spline basis functions known from Computer Aided Design (CAD) to describe the geometry and the solution field. Employing such spline basis functions with higher order and higher continuity may yield several advantages such as an easier transition from CAD to analysis, a more accurate geometry description, smooth solution fields or a larger time step in explicit analysis. In fact, only the higher-continuity property of splines enables the concept of trimming (ubiquitous in CAD) to be used in explicit analysis with a feasible time step size [2].

• Recent Enhancements on Short-Fiber Reinforced Plastics Modeling in LS-DYNA

  C. Liebold, A. Erhart (DYNAmore)

  A two-scale constitutive model for short-fiber reinforced plastics is currently being realized in LS-DYNA associated with an appropriate data-mapper (DYNAmap). For reliable structural analysis of heterogeneous materials like SFRP, the anisotropic and locally varying effective elastic properties are determined through a homogenization process of the microstructure and provided for the structural analysis.

• Recent Enhancements to the GISSMO Failure Model in LS-DYNA

  André Haufe - DYNAmore GmbH, Markus Feucht, Frieder Neukamm - Daimler AG, Paul DuBois - Consultant

• Recent Improvements in LS-DYNA® Metal Forming Material Models

  Jinglin Zheng, Xinhai Zhu, Livermore Software Technology Corporation

  This paper solves two numerical issues arising from the return mapping scheme when simulating metal forming processes with LS-DYNA: (1) the returning mapping process fails to converge in cases where the effective plastic strain increment is small; (2) even when full convergence is accomplished at each time step, the global solution may diverge under small time step settings. For the first issue, a stable iterative scheme with global convergence is implemented to substitute the original secant algorithm which is only locally convergent. For the second issue, a variable tolerance is introduced to control the local error when necessary and hence improve the global convergence. Two examples are given to demonstrate the effectiveness of these methods.

• Recent Improvements to Release III of the K&C Concrete Model

  Joseph M. Magallanes, Youcai Wu, John E. Crawford - Karagozian & Case, L. Javier Malvar - Naval Facilities Engineering Service Center

  Recent improvements are made to Release III of the Karagozian & Case (K&C) concrete model. This three- invariant plasticity and damage-based constitutive model is widely used to model a number of materials, including normal and lightweight concrete, concrete masonry, and brick masonry, to compute the effects of quasi-static, blast, and impact loads on structures. This most recent version of the model, made available starting with LS-DYNA® v971 as *MAT_CONCRETE_DAMAGE_REL3, incorporates a number of improvements to the original model that are described in this paper. The model now exhibits: (a) an automatic input capability for generating the data for generic concrete materials and (b) methods to reduce mesh-dependencies due to strain-softening. A simple method is implemented to regularize the fracture energy by internally scaling the damage function for the generic concrete model parameters. For user-defined material parameters, a method is developed that can preserve fracture energy using the results of either single-element or multi-element simulations. Finally, concrete loading rate effects are discussed and guidance is provided on properly modeling such effects with the model.

• Recent Investigations of Side Curtain Airbag Deployment Simulation using CPM

  Hisaki Sugaya, Kazuo Imura, Hiroyuki Mae (Honda R&D Co.,Ltd.)

  Recently, Honda has shifted to a vi_ual development process to shorten the development term. In addition, the virtual development process has also been applied in the crash safety one. for this reason, it is necessary to build more accurate simulation modelling method. There are some reports, in which, airbag modelling Methods about gas flow has several technical issues [1] [2] [3I, in the crash safety components. Therefore, this research focuses on simulating the airbag folding properties and deployment behaviour. This study introduces the modelling method of the side curtain airbag (SCAB) with its complicated structure, leading to the accurate deployment simulation.

• Recent LS-DYNA Developments in the Structural Conjugate Heat Transfer Solver

  T. Klöppel (DYNAmore)

  Increasing demands for the simulation of complex, multi-physics problems in crashworthiness and manufacturing process analyses have necessitated new developments in the structural conjugate heat transfer solver in LS-DYNA®. Some of the most recent extensions and new implementations are presented and discussed in this contribution. The first block addresses the relatively new field of battery abuse simulations. Focus is put on a novel thermal composite thick shell element that is defined using *PART_COMPOSITE_TSHELL. On the one hand, the implementation allows for a relatively easy input definition. On the other hand, the formulation adds new temperature degrees of freedom for each layer of the composite structure and, thus, accurately resolves the internal lay-up of the structure, i.e. the battery cell. The reconstructed lay-up is also accounted for in the thermal contact routines. Consequently, the heat transfer through a stack of solid elements can be reproduced exactly by a single composite thick shell element with the corresponding lay-up definition. The second block presents the work on different thermal boundary conditions. A recent enhancement enables the “standard” boundary conditions (convection, radiation, and flux) to be transferred to newly exposed surfaces after element erosion. In general, this is sufficient for modeling laser cutting with a flux boundary condition, but the input of such a model can become very complex. Therefore, a new thermal boundary condition *BOUNDARY_FLUX_TRAJECTORY is introduced in the second part of this block, which is tailored for moving heat sources acting on the surface of a structure. In contrast to the standard flux boundary condition, the new implementation also accounts for the tilting of the heat source. The boundary condition is applicable in coupled thermal-structural and thermal-only simulations. The second block is completed by the presentation of a new temperature boundary condition *BOUNDARY_TEMPERATURE_RSW that is devised as a simplified modeling strategy for resistive spot welds (RSW). With the keyword, the temperature distribution in a weld nugget is defined directly.

• Recent New Developments in Contact Mechanics

  P. Wriggers, K. Fischer - University of Hanover, A. Rieger - Continental AG

  During the last years considerable effort was devoted to better numerical treatment of contact problems. This fact is due to the growing computing power which lead to more and more sophistication and detailed technical models within engineering analysis. Due to the more precise modelling within the associated discretization process often unilateral constraints have to be considered. Hence better discretization techniques, especially for finite deformations, are needed to solve problems with contact constraints in an efficient and robust way. In this paper we will discuss some recently developed discretization schemes and algorithms for the treatment of contact constraints. The presentation is split into two parts. The first one is devoted to discretization techniques for contact problems which fulfill the BB-condition needed for a stable contact discretization scheme. This leads to a discussion of weak enforcement of the contact constraint conditions which results in so-called mortar methods for linear and nonlinear problems. Here also special remarks are made with regard to efficient solution schemes which are based on a total gap vector at the contact interface. The second part of the presentation is related to adaptive finite element methods for large deformation thermo-mechanical contact problems. Here a special staggered scheme is developed in which different finite element meshes are combined to solve the thermo-mechanical contact problem. Based of the methodology of the Zienkiewicz, Zhu error indicators based on superconvergent patch recovery special error indicators are developed for the the mechanical and thermal part of the problem including the contact constraints. Furthermore an error indication in time is derived for the thermal heat conductance equation based on a time-space discretization which uses a continuous Galerkin scheme for the time integration. Using such integration algorithm one can derive again a error indicator by assuming superconvergent time points. This method is applied to solve an example with known analytical solution which allows the computation of efficiency indices. Here it can be shown that the developed adaptive time stepping scheme results in very good efficiency of the method. For all parts, the basic theoretical basis is derived, algorithmic implications are discussed and explanatory examples are presented to show the properties of formulations when compared to existing ones.

• Recent Research and Developments of LS-DYNA's User Subroutine in JSTAMP/NV

  T. Amaishi, N. Ma, Y. Umezu (JSOL Corporation)

  Sheet metal forming simulation has been widely used in die design process, in order to make lightweight products ®and shorten production lead time. JSOL Corporation has been developing JSTAMP/NV since 1996 and continuously supplying the best stamping simulation environment for users. One of the most competitive advantages of JSTAMP/NV is its accuracy on the evaluation of formability when using explicit and implicit solutions in LS- ®DYNA . In this paper, new material model and user subroutine of anisotropic plasticity with temperature dependency were developed for hot forming simulation by authors. Using the developed material model, the formability of deep drawing of a magnesium alloy was estimated with the high accuracy compared with experimental results.

• Recent Updates for the Heat Transfer Solver in LS-DYNA ® with focus on computational welding mechanics

  Thomas Klöppel (DYNAmore GmbH), Mikael Schill (DYNAmore Nordic AB), Tobias Loose (Ingenieurbüro Tobias Loose)

  Even though welding is a well-established production process in manufacturing industries and it has a significant influence on the finished geometry as well as on the material properties of the processed part, it is still often ne- glected in the virtual process chain. In this contribution novel developments for the heat transfer solver in LS- DYNA ® are presented, which are designed to close this gap in the virtual process chain. First of all, the new keyword *BOUNDARY_THERMAL_WELD_TRAJECTORY is presented that provides an easy and flexible input structure for a heat source moving along a prescribed and, possibly, geometrically complex path for thermo-mechanically coupled and thermal only simulations. As the user can choose from a list of pre-defined equivalent heat source models and this list is very easily extendable, the new feature is potentially applicable to all fusion welding processes. Due to high temperatures, high temperature gradients and very high temperature rates present in welding applica- tions, phase transformations in the microstructure of the material play a crucial role in the process. The new LS- DYNA material model *MAT_GENERALIZED_PHASE_CHANGE/#MAT_254 allows to distinguish between up to 24 different phases in the microstructure. For each of the possible phase transitions the user can choose from a list of generic and well-established transformation models. Therefore, the model is for example applicable to a wide range of steel and aluminium alloys. Transformation induced plasticity and strains as well as annealing effects have also been incorporated into the new material formulation.

• Recent Updates in LS-DYNA Frequency Domain Solvers

  Y. Huang, Z. Cui (LSTC)

• Recent Updates to the Structural Conjugate Heat Transfer Solver

  Thomas Kloeppel, Peter Vogel, DYNAmore GmbH, Stuttgart, Germany

  In this contribution recent developments in the structural conjugate heat transfer solver in LS-DYNA® are presented and discussed. The motivation for new implementations results from the specific needs in complex manufacturing processes such as for example hot forming, heat treatment and welding or multi-physics problems such as battery modelling. The paper first addresses two new options for the thermal contact. First of all, heat transfer between a shell edge and a surface (either shell or solid face) can now be considered. Second, a special welding contact formulation has been implemented. Above a certain temperature, the formulation switches from a sliding to a tied formulation and uses different parameters for the heat transfer. Although both modifications have been motivated by line welding simulations, they have also proven to be helpful for other applications.

• Reconstruction of Trimmed and Faceted Vehicle Models for Isogeometric Analysis in LS-DYNA

  K. Shepherd (Brigham Young University), X. D. Gu (Stony Brook University), T. J. R. Hughes (University of Texas)

  The traditional engineering design-through-analysis process is inadequate for modern needs. In it, an engineering designer will create a model in a computer-aided design (CAD) software, after which an analyst takes this smooth CAD model, defeatures it, cleans up the model, and ultimately approximates the intended shape as a faceted, semi-structured mesh for subsequent engineering analysis. Analysis, thus, no longer operates on the intended object, but instead evaluates physics on a faceted approximation, which may lead to compromised results [1]. Furthermore, while design and analysis are the primary objects of interest in the design-through-analysis process, the intermediary steps of geometry cleanup and meshing consume over 70% of the time spent in the design-through-analysis process [2, 3]. Naturally, this leads to increased associated costs [4].

• Reduced Ductility due to Local Variation in Material Properties for 3D-Printed Components

  T. Tryland (Sintef Raufoss Manufacturing)

  It is often useful to have a physical model to display geometry as an alternative to the 3D-model on a computer screen. In addition, 3D-printed components may work well to evaluate the assembly process. The question here is whether parts that are manufactured in this way have representative ductility to give valuable results in structural tests where the material is loaded outside the elastic regime. There is a wide range of processes and printers available, and is it possible to get more realistic material properties with an expensive machine compared with a simpler one? It is likely that 3D-printed components may have local variation in the material properties, and a study on an aluminium alloy for crashboxes shows that this phenomenon may reduce the ductility [1]. Uniaxial tensile tests may not detect the effect due to sufficient strain hardening for small strains. It may be better to use a shear test that evaluate the material into a higher degree of deformation [2]. However, axial compression with a sensitive geometry may clearly demonstrate the effect when the lowest of several deformation modes at the same force level suddenly wins and this result in a brittle behaviour.

• Reduced Order Model for enhanced EVAR Planning and navigation guidance

  Monica Emendi, Eirini Kardampiki, Karen H. Støverud, Pierluigi di Giovanni, Sigrid K. Dahl, Aline Bel-Brunon, Victorien Prot, Marco E. Biancolini

  Endovascular aneurysm repair (EVAR) is a minimally invasive procedure for the treatment of abdominal aortic aneurysms that consists in stent graft deployment through the iliac arteries [1]. During this procedure, a stiff guidewire is introduced from the femoral artery towards the aorta to support the proper deployment of the stent graft. The insertion of the stiff wire triggers a straightening effect on the iliac arteries, smoothing out their natural tortuosity [2]. This morphological alteration is hard to be measured intraoperatively or be forecasted preoperatively [3]. The main bottleneck is that the preoperative Computed Tomography (CT) does not get updated during the operation. Consequently, clinicians perform their maneuvers according to the initial aortic configuration and inject contrast in the vessel to visualize their configuration when it is needed. This practice could possibly lead to sub-optimal stent graft sizing, choice of the stent’s landing zone and to an increase in radiation exposure and contrast doses, especially in complex cases.

• Reduction in Time to Market of Automotive Seating System Using LS-DYNA

  Hurshkumar G. Donde, Rakesh K. Lad, Prabal Kumar Biswas, Praveen B. Patil - Infosys Technologies Limited, Gordon Stace - Johnson Control Automotive UK Limited

  The worldwide automotive industry is going through a sea change in order to get the share in the global market, which is becoming highly competitive & dynamic. The automotive OEM’s are faced with conflicting demands & challenges. There is an increasing demand for cost & weight reduction, fuel economy & reduction in time to market on one hand and on the other hand there is even more increasing demand towards assuring improved occupant safety and comfort in complex crash & driving conditions besides the pressure from environmental regulations. The safety and environmental regulations are becoming increasingly stringent in the developed economies & the developing economies are catching up. These factors are driving the change in entire automotive industry value chain and the major sub systems suppliers are directly affected by this. One such sub-system is seating system, as it is major contributor to the occupant safety & comfort. The automotive seating system development process is becoming highly complex and challenging as the regulations pertaining to NVH (Noise, Vibration & Harshness)/ durability/ fatigue, static/dynamic strength and crash safety are becoming increasingly stringent besides OEM’s pressure to reduce weight and cost. One of the major challenges is to reduce the time and the cost of developmental prototyping and testing. As a result most of the forward-looking organisations are beginning to move towards Virtual Product Development Environment (VPD). One of the most useful tools available to virtually simulate product performance under various dynamic conditions is LS-DYNA. This paper depicts the evolution of a rear seat system for the Ford Focus vehicle through effective use of LS-DYNA and other CAE tools, throughout the developmental life cycle. This program demanded a reduced program timeline of 18 months.

• Reduction of Acceleration Induced Injuries from Mine Blasts under Infantry Vehicles

  Ala Tabiei, Gaurav Nilakantan - University of Cincinnati, USA

  Anti tank (AT) mines and improvised explosive devices (IED) pose a serious threat to the occupants of infantry vehicles. The use of an energy absorbing seat in conjunction with vehicle armor plating greatly improves occupant survivability during such an explosion. The dynamic axial crushing of aluminum tubes constitutes the principal energy absorption mechanism to reduce the blast pulse transmitted to the occupant in this investigation. The injury mechanisms of both vehicle-occupant contact interfaces are simulated viz. vehicle seat upon the occupant’s torso and vehicle floor upon the occupant’s feet. Data such as hip and knee moment, femoral force, and foot acceleration is collected from the numerical dummy which simulates the occupant’s response. This data is then compared to injury threshold values from various references to assess survivability.

• Relating scatter in occupant injury time histories to instability in airbag behaviour

  Richard Brown (Jaguar Land Rover), Dominik Borsotto (Fraunhofer Institute SCAI), Clemens-August Thole (SIDACT GmbH)

  Dealing with natural variation in input parameters and environmental conditions presents the automotive industry with significant challenges. Lack of consideration of variability in results can lead to unpleasant surprises during testing, with a consequent risk of unplanned cost and delay. In a purely virtual product development world, analysis techniques must lead to designs that are robust with respect to external noise sources, in order to minimise test-to- test and test-to-prediction variation. This paper discusses some of the issues faced in dealing with variability in an occupant restraint system, and presents an analysis approach that is helping to provide insight into causes of scatter, leading to potential design improvements to help reduce it. Conventionally the CAE process has used nominal values for input parameters, and has been satisfied with single, deterministic solutions. In many cases this approach is based on unreasonable assumptions, and a structured consideration of variability is vital. In this context we describe an example where Principal Components Analysis has been used to study scatter in an airbag model. Building on previous experience with the application of this technology to deformed geometries, the technique has been extended to allow a consideration of scatter in curves, as exemplified by the set of chest acceleration time-histories shown in figure 1. The mathematical background to the PCA method, as implemented in Diffcrash, is presented, and its extension to curves is explained. It will be shown how scatter in two crash dummy channels can be related to each other and to airbag deformation behaviours, as an aid to developing design improvements. Virtual techniques have much to offer in understanding and managing scatter in physical systems, and the consideration of variability in the CAE process is slowly becoming more common-place. The PCA approach presented here is a useful addition to the toolset available, giving valuable insight into physical phenomena.

• Reliability-based Multi-Objective Optimization and Visualization using LS-OPT Version 4

  Nielen Stander, Willem Roux, Tushar Goel- Livermore Software Technology Corporation, David Björkevik, Christoffer Belestam - Engineering Research AB, Katharina Witowski - DYNAmore GmbH

  This study expounds the multi-objective optimization of a realistic crashworthiness problem with special reference to the incorporation of uncertainty and the visualization of the Pareto Optimal Frontier (POF). LS-OPT® and LS-DYNA® are used for the optimization based on the C2500 truck model developed by NHTSA. The design problem is set up as a Reliability-Based Design Optimization (RBDO) problem which includes specifications for the variation of the input parameters. For the purpose of design, reliability-based constraints on the displacements and stage pulses (interval-based integrals over the acceleration history) are specified. Nine thickness variables were assigned to various parts affecting the crashworthiness performance. Solution of the example employs Radial Basis Function networks as surrogate functions with Space Filling sampling as well as the NSGA-II algorithm for determining the POF starting from an infeasible design. Post-processing is done to determine a subset of optimal points of interest using the Viewer of LS-OPT® Version 4. This post- processor is based on a new architecture which allows window splitting and detachable windows for flexible viewing. It also includes the following new features: (1) Correlation Matrix, (2) Parallel Coordinate plot (POF) and (3) Hyper-Radial Visualization (POF). Thus 3 types of POF viewing are available, including the current 3D scatter plot. The study shows that a complex decision-making process such as optimal design involving uncertainty and multiple objectives can be simplified by using appropriate analysis and visualization tools.

• Reliability-based Multi-Objective Optimization and Visualization using LS-OPT Version 4

  Nielen Stander, Willem Roux, Tushar Goel- Livermore Software Technology Corporation, David Björkevik, Christoffer Belestam - Engineering Research AB, Katharina Witowski - DYNAmore GmbH

  This study expounds the multi-objective optimization of a realistic crashworthiness problem with special reference to the incorporation of uncertainty and the visualization of the Pareto Optimal Frontier (POF). LS-OPT® and LS-DYNA® are used for the optimization based on the C2500 truck model developed by NHTSA. The design problem is set up as a Reliability-Based Design Optimization (RBDO) problem which includes specifications for the variation of the input parameters. For the purpose of design, reliability-based constraints on the displacements and stage pulses (interval-based integrals over the acceleration history) are specified. Nine thickness variables were assigned to various parts affecting the crashworthiness performance. Solution of the example employs Radial Basis Function networks as surrogate functions with Space Filling sampling as well as the NSGA-II algorithm for determining the POF starting from an infeasible design. Post-processing is done to determine a subset of optimal points of interest using the Viewer of LS-OPT® Version 4. This post- processor is based on a new architecture which allows window splitting and detachable windows for flexible viewing. It also includes the following new features: (1) Correlation Matrix, (2) Parallel Coordinate plot (POF) and (3) Hyper-Radial Visualization (POF). Thus 3 types of POF viewing are available, including the current 3D scatter plot. The study shows that a complex decision-making process such as optimal design involving uncertainty and multiple objectives can be simplified by using appropriate analysis and visualization tools.

• Resistance Spot Welding in LS-DYNA®: An Overview of Current Capabilities

  Iñaki Çaldichoury Pierre L’Eplattenier (Livermore Software Technology, an Ansys company)

  Resistance spot welding is perhaps the most frequently encountered joining method for steel sheet in the automotive industry. It is accomplished by passing an electrical current through metal sheets via electrodes. The sheets are held together under the pressure exerted by the electrodes and heat is induced by the electrical current which generates a molten nugget between the sheets. The molten nugget then solidifies to form a bond. During the spot welding process, important changes occur in mechanical and metallurgical properties of the spot welded areas and heat affected zones appear. Although routinely used by the industry, the physics involved in the process are far from trivial, and generally involve a combination of electrical, mechanical, thermal, and metallurgical fields. In particular, the contact area between electrode and workpiece generates an additional electric contact resistance dependent on the models parameters. This contact resistance will have a decisive impact on the shape and size of the nugget and therefore the weld’s quality. Furthermore, the development of new materials such as advanced high strength steels or the replacement of steel by aluminum in certain automotive parts further increases the complexity of the process. Numerical tools and finite element analysis (FEA) can on the other hand offer a crucial assistance in the comprehension of the phenomena involved. Numerically, setting up the RSW model consists in a challenging and highly non-linear problem where solid mechanics, thermal and EM quantities interact with each other. The interface area is especially critical, a robust electric contact algorithm is needed to accurately distribute the local extra resistance to the faces that are in contact with one another so that the correct heating can be calculated and passed on to the thermal solver, even in complex cases with different density meshes and shapes. Over the years, several developments have been introduced in LS-DYNA in order to tackle this problem and in this paper, an overview of the current capabilities will be given along with some example description so that potential users can gain a better understanding of what to expect.

• Resistive Spot Welding Simulations Using LS-DYNA

  P. L'Eplattenier, I. Caldichoury (LSTC); T. Loose (DynaWeld)

  Resistance Spot Welding (RSW) is a very important welding process for thin sheet metals with many applications, in particular in the automotive industry. In this method, the contacting metal surfaces are joined by the heat obtained by Joule heating of an electrical current flowing through resistances. These resistances are composed of the bulk resistance of the parts being welded, and of the contact resistances at the interfaces between the electrodes and the sheets, and between the sheets. The amount of Joule heating energy delivered to the spot is determined by the magnitude and duration of the current and the values of the resistances. The resistances usually depend on the geometry, material properties and temperature: the bulk resistance of the metals is temperature dependent, and the contact resistances depend on the local contact pressures and temperature. The electrical conductivities of the materials and the yield stress are also used in some models to predict the contact resistance. The current flow then depends on the local values of the bulk and contact resistances. It is thus very important to have a model which captures all these phenomena. Recently, the contact resistance model in the EM solver of LS-DYNA has been extended to allow RSW simulations, where the user can define a local contact resistance as a function of different local contact parameters, using a *DEFINE_FUNCTION. The EM solver has also been adapted so that the current flow takes into account the local contact resistances. The local Joule heating is added to the thermal solver, and temperature dependent electrical conductivities can be taken into account via EM EOS's. The model will be presented, then we will show how to set up a RSW case, and will present some results and benchmarks with experiments.

• Response of a Large Span Stay Cable Bridge to Blast Loading

  Cezary Bojanowski (Argonne National Laboratory), Marcin Balcerzak (Warsaw University of Technology)

  The computational analysis of engineering structures under blast loads faces three fundamental problems: (i) reliable prediction of blast loads imposed on structures, (ii) correct representation of material behavior, and (iii) global analysis of large scale structures. Despite the recent developments in Finite Element (FE) codes like LS-DYNA® and advancements in computational power, addressing all of these issues in a single simulation is not a straightforward task. In this paper, LS-DYNA capabilities were utilized to simulate the transient global response of a long span cable stayed bridge subjected to blast loading over the deck and to evaluate localized damage to the deck structure. Described in detail is the development of a global FE model of the Bill Emerson Memorial Bridge – a cable-stayed bridge crossing over the Mississippi River near Cape Girardeau, Missouri. The global model takes into account the structural details of the deck, support columns and the pretension in the stay cables. It was partially validated by comparing the calculated natural frequencies with those previously extracted by the Missouri Department of Transportation from data recorded during the 2005 earthquake of M4.1 on a Richter scale (Assessment of the Bill Emerson Memorial Bridge, Report No. OR08-003, September 2007). A detailed model of the central section of the deck was developed to simulate localized damage. Boundary conditions on the detailed model were applied through a sub-modeling technique based on the analysis of the global simplified model. The results show that a detonation of explosives of a typical size of passenger car and van bomb on a traffic lane in the mid span of the deck is not likely to cause a collapse of the bridge. The vibrations in the stay cables do not lead to yielding of the steel in the strands. The simulation of the local damage shows that – for the chosen van location – the blast may perforate the deck and deform the cross beam. The extent of the damage, however, depends greatly on the assumed erosion criteria.

• Response of the Enhanced Polar Outflow Probe (e-POP) Instrument Under Shock Loading

  M. Nejad Ensan, D.G. Zimcik - National Research Council Canada

  Spacecraft components encounter mechanical shock from a variety of sources. Components must withstand a series of flight shock pulses, and must be designed and tested accordingly to ensure reliability. This paper presents simulation of the response of the Enhanced Polar Outflow Probe (e-POP) instrument to the shock loading, during payload separation, using LS-DYNA® nonlinear finite element analysis software. Details of the model and simulation approach and the results obtained from that analysis are included in this paper. The mission science objective of the e-POP is to study plasma and atmospheric outflows in the polar region and the wave generation, particle interaction, and propagation associated with these outflows. The e-POP Instrument payload is a part of the "CASade, Smallsat and IOnospheric Polar Explorer" (CASSIOPE) mission. The CASSIOPE mission is a joint mission for the development and demonstration of key CASCADE technologies for future global bulk data delivery system, the development and demonstration of a generic SmallSAT Bus for future Canadian Space Agency (CSA) space missions.

• Response Spectrum Analysis and DDAM Analysis in LS-DYNA®

  Yun Huang, Zhe Cui (Livermore Software Technology, an ANSYS Company)

  Response spectrum analysis (keyword *FREQUENCY_DOMAIN_RESPONSE_SPECTRUM) evaluates the peak response of structures subjected to various loads like ground motions in an earthquake. It combines contribution from each vibration mode of the structures. This feature has important application in Civil and hydraulic engineering, where seismic analysis is critical to the design and safety evaluation of the large scale buildings. DDAM (Dynamic Design Analysis Method) is a U.S. Navy-developed analytical procedure for shock design. It helps validate the design of onboard equipment and structures subject to dynamic loading caused by underwater explosions (UNDEX). It is a widely accepted procedure for safety evaluation for civil and military ship building. The keyword for response spectrum analysis (*FREQUENCY_DOMAIN_RESPONSE_SPECTRUM) in LS-DYNA has been extended to run DDAM analysis for shipboard components, with the option _DDAM. This paper first gives a brief review of the theory for response spectrum analysis and DDAM analysis. Then, with several examples, this paper shows how to run response spectrum analysis and DDAM analysis with LS-DYNA and how to perform post-processing of the results. For purpose of cross-validation, the results of DDAM analysis with LS-DYNA are compared with that given by other commercial code.

• RESPONSE SURFACE AND SENSITIVITY-BASED OPTIMIZATION IN LS-OPT: A BENCHMARK STUDY

  Nielen Stander - Livermore Software Technology Corporation, K.J. Craig - University of Pretoria

  This paper evaluates the robustness of LS-OPT for response surface and design sensitivity-based optimization. The methodology uses linear response surfaces constructed in a subregion of the design space. These are constructed using either a design of experiments approach with a D-optimal experimental design or the available analytical or numerical gradient. The approach utilizes a domain reduction scheme to converge to an optimum. The scheme requires only one user-defined parameter, namely the size of the initial subregion. To test its robustness, the results using the method are compared to SQP results of a selection of the well-known Hock and Schittkowski problems. Although convergence to a small tolerance is predictably slow when compared to SQP, LS-OPT does remarkably well for these, sometimes pathological, analytical problems.

• Retrofitting of Reinforced Concrete Beam-Column via Steel Jackets against Close-in Detonation

  S. H. Tan, J. K. Poon, R. Chan, D. Chng (Ministry of Home Affairs)

  This paper presents results from simulation, in comparison to findings from full-scale blast trials of Reinforced Concrete Beam-Column test specimens. 2 numerical approaches were adopted. First method was a 2-stage approach which involved applying segment pressure loadings, derived from Computational Fluid Dynamics (CFD) ®calculations, on LS-DYNA Lagrangian models to predict structural response. Second method was the use of *Load_Blast_Enhanced keyword to couple empirical blast loads to air domain in Arbitrary Lagrangian-Euler (ALE) environment for direct LS-DYNA Fluid-Structure Interaction (FSI) computations. Grid Convergence Index (GCI) principles were used to check adequacy of mesh refinement studies.

• Review and Advances of Coupling Methods for the ICFD Solver in LS-DYNA

  F. Del Pin, I. Caldichoury, R. Paz (LSTC)

  The ICFD solver in LS-Dyna specializes in the solution of Incompressible fluid flows. The main goal is to accurately predict the values of pressure and velocity subject to the constraint that Div(v)=0 where v is the fluid velocity. One area of applications is the prediction of lift and drag in aerodynamics of external flows, detachment or recirculation for internal flows, etc. These are what could be regarded as typical CFD applications. The real potential of the ICFD solver arises when it is coupled to other solvers within LS-Dyna. In this paper the numerous existing coupling methods available for the ICFD solver will be reviewed. Also in this paper the latest advances regarding to coupling methods will be presented. In terms of coupling ideas the following will be discussed: Fluid Structure Interaction (FSI) weak and strong, Conjugate heat transfer weak and strong and the addition of electromagnetism as part of the coupled solution. Also the coupling with the Discrete Element Method (DEM) will be introduced enumerating the different features available in the coupling process. Finally a new variation that incorporates the steady state solver coupled to a static linear or non-linear structural solution will be presented.

• Review of Sheet Metal Forming Simulation Progress to Date, Future Developments

  Trevor Dutton - Dutton Simulation Ltd

  Sheet metal forming simulation is a well established application of LS-DYNA. Originally used for trouble shooting, it is now increasingly accepted as a method for testing tooling design prior to manufacture; however, there are further opportunities to apply such methods as early as possible, even in the product design stage. This paper reviews the advances of recent years and presents an example of typical current applications; the tools now offered for die face creation are then discussed. The paper also looks ahead to see how application of these methods might develop and indicates areas for research, in order to achieve the maximum benefit from simulation.

• Road Safety Devices Assessment for Sliding Motorcyclists Protection

  M. Anghileri, L. Castelletti, A. Milanese, M. Pirola, F. Pistochini - Politecnico di Milano, Italia

  Statistics show that the impact with a roadside safety barrier of a motorcyclist sliding on the pavement after an accident is potentially more dangerous than the accident itself. In recent years, in effort to avoid the most serious consequences, the approach to barriers design changed and specific devices have been introduced to improve motorcyclists’ safety. At LAST Crash Labs, the effectiveness of one of these devices was experimentally and numerically investigated. A good numerical-experimental correlation was obtained and, in view of that, it was concluded that the numerical approach is a rather reliable tool for the development of devices for motorcyclists’ protection.

• Robust FEM-BEM Coupling for LS-DYNA®'s EM module

  Lars Kielhorn, Thomas Rüberg, Jürgen Zechner, TAILSIT GmbH

  The electromagnetic (EM) solver module of LS-DYNA targets coupled mechanical/thermal/electromagnetic problems as they occur, for instance, in the simulation of metal forming, welding, and induction heating. The EM solver incorporates the coupling of Finite Element and Boundary Element Methods. The main advantage of this approach is that the volume discretization of the surrounding air region is avoided. This approach significantly reduces the modelling time and avoids mesh entanglement due to large deformation of the workpiece in metal forming.

• Robust Modelling and Validation Analysis on the Raffles City Chongqing Project

  Zhi-Gang Liu, Shi-Chao Wu, Xiao Dong, Francois Lancelot, Li-Gang Zhu (Arup)

  Since 2012, Arup has been providing structural engineering services for all design stages of the development of the Raffles City Chongqing (RCCQ). This truly iconic mega-complex has been designed by the internationally acclaimed architect Moshe Safdie for the developers CapitalLand and Singbridge Holdings. Various structural schemes for the 300m-long sky deck atop the four 250m-high interior towers have been assessed using LS-DYNA [1]. Extensive nonlinear time-history analyses have been performed to simulate the behavior of several conservatory articulations and isolation solutions under extreme seismic conditions. Arup Shanghai has also been investigating innovative fuse/concrete outrigger solutions to meet the wind/seismic demands on the 350+m North Towers (T3N and T4N). A hybrid steel diagonal and concrete wall outrigger system (Hybrid OT wall) proved particularly promising. Compared with traditional steel designs, a Hybrid OT wall would simplify the design of the wall-to-mega-column connection while being significantly cheaper in cost. The development of these elements required extensive Finite Element analyses and physical testing. By deploying advanced LS-DYNA capabilities, structurally reliable and cost-efficient options have been identified and validated. This paper presents the validation process, analysis results and the design solutions that could achieve the architecturally ambitious, safe and sustainable design while providing significant cost savings.

• ROBUST PARAMETER DESIGN IN LS-OPT

  Willem Roux - LSTC

  Robust parameter design creates designs insensitive to the variation of specific inputs. The paper discusses the robust parameter design capability within the context of its implementation in LS-OPT version 3.2. The paper provides the following details: the fundamentals of robust parameter design, the design of experiments based methodology used in LS-OPT, and an example problem.

• Robustness Analysis of a Vehicle Front Structure Using Statistical Approach

  M. Okamura (JSOL)

  In this study, a process for assessing the robustness of designs has been presented, and the results are discussed using front structures of a vehicle FE model as an example. Statistical approaches have been introduced in order to assess the robustness of the structural design. Dozens of numerical simulations have been conducted taking into account uncertainties in input parameters such as spotweld failure criteria. The scatters in input parameters and the resultant deformations are statistically analyzed using a tool DIFFCRASH in order to capture the timing and location of bifurcations, and to understand the mechanisms inducing scatters in results.

• Robustness Evaluation Crashworthiness Simulation Results

  Johannes Will - DYNARDO GmbH, Uli Stelzmann - CADFEM GmbH

  The numerical robustness of simulation results from explicit time integration is an important topic. We know for real world applications of passive safety and crashworthiness that we have some numerical noise, but the interesting question is if that really does influence significantly our simulation results. Furthermore, today the robustness of the designs against naturally given input scatter, in loading conditions, geometry or material become part of the virtual product development process. Then, the prognosis of the variation of important simulation results using stochastic analysis procedure is necessary. Again the question arises how much of the calculated variation is coming from numerical noise. The paper will present a procedure of numerical robustness evaluation using stochastic analysis to quantify the scatter of simulation results. Using coefficients of determination, a procedure of deselecting variation defined by correlation to physical input scatter and "undefined" variation is introduced. The breakthrough in practical application and the acceptance of stochastic analysis for robustness evaluations was achieved by using linear and quadratic correlations and the corresponding measures of determination as well as by projection of statistical measures on the finite element structure.

• Robustness Study of an LS-DYNA Occupant Simulation Model at DaimlerChrysler Commercial Vehicles Using LS-OPT

  Dr. Frank C. Günther - DaimlerChrysler, Dr. Heiner Müllerschön, - DYNAmore GmbH, Dr. Willem Roux - Livermore Software Technology Corporation

  The robustness properties of crash simulation models are emerging as an important criterion in today's simulation driven vehicle development process. We consider it relevant to any study of highly non-linear crash problems to obtain measures for the repeatability and reliability of both experimental and numerical tests. In 2003, we conducted a robustness study of a structural front impact model (JAPAN LS-DYNA Users Conference 2003) using the Meta-Model concept of LS- OPT. This study seemed to indicate that there is an inherent, residual randomness in crash problems. In the present paper, we present a new robustness study of a frontal sled test occupant model with a 50th percentile FTSS dummy. Our goals were: • Determine variations of typical occupant safety responses such as HIC, chest intrusion, and others due to uncertainties in the experimental setup, including dummy position, airbag mass flow, and acceleration. • Separate deterministic and residual, random variations of responses using the Meta-Model technique. • Get a feeling for random variations inherent in occupant studies. • Evaluate the generality of these robustness results through a convergence study varying the number of simulation experiments and variables for the Meta-Model.

• Roll Forming Simulation using Higher Order NURBS-based Finite Elements

  P. Glay (DYNAmore France), S. Hartmann (DYNAmore)

  Roll forming is a continuous bending operation of a long strip of metal sheet. The sheet is gradually formed through pairs of rotating rolls (called stands) until the desired cross-sectional configuration is obtained (see Fig. 1). Although roll forming is a classical method to produce constant cross-sectional profiles, it remains a complex process. Finite element analysis (FEA) can assist the designer to improve this process

• RollerPaG – a Tool for the Automatic Path Generation for Roller Hemming Simulation using LS-DYNA

  B. Boll (DYNAmore), O. Ghouati (Ford Research & Advanced Engineering)

  Compared to tool or table-top hemming, the roller hemming is unique by its specific kinematic. A robot guides a roller along the flange to perform the hemming, with more than one robot used for an assembly in order to speed up the process. Main advantages of the roller hemming are low investment for a new product and short lead time to design and manufacture product specific equipment. Application of roller hemming was up to now restricted to low and middle volume production, though new developments made it more suitable for higher production volumes as well.

• Rollover Simulations for Vehicles using Deformable Road Surfaces

  T. Palmer (ETA), B. Honken (ETA), C. Chou (Wayne State University)

  Vehicle Rollover simulations have been performed using LS-DYNA to predict both the vehicle dynamics and structural performance. However, these simulations do not consider a deformable road surface, affecting both the propensity of the vehicle to achieve a condition which will initiate a roll over or the effect of that surface to impart or mitigate damage to the structure. This study will highlight the capabilities of LS-DYNA for the simulation of deformable road surfaces as applied to rollover events.

• Roof Crush Resistance and Rollover Strength of a Paratransit Bus

  Cezary Bojanowski Transportation Research and Analysis Computing Center, Argonne National Laboratory, Bronislaw Gepner, Christopher Rawl, Jerry Wekezer - FAMU-FSU College of Engineering, Leslaw Kwasniewski - Warsaw University of Technology, Faculty of Civil Engineering

  Paratransit buses constitute a special group of vehicles in the US due to their smaller size, two-step assembly process, and their use for complementary services to the regular scheduled transit routes. Due to their uniqueness these buses lack national crashworthiness standards specifically dedicated to the paratransit fleet. Several states in the US adopted the quasi-static symmetric roof loading procedure according to the standard FMVSS 220 for testing the integrity of the paratransit buses. However, as many researchers point out, the dynamic rollover test according to UN-ECE Regulation 66 (ECE-R66), which was approved by more than forty countries in the world, (excluding the US), may provide more realistic assessment of the bus strength.

• Roof Rail Airbag Folding Technique in LS-PrePost ® Using DynFold Option

  Vijay Chidamber Deshpande (GM India – Tech Center), Wenyu Lian (General Motors Company), Amit Nair (LSTC)

  A requirement to reduce vehicle development timelines is making engineers strive to limit lead times in analytical simulations. Airbags play a crucial role in the passive safety crash analysis. Hence they need to be designed, developed and folded for CAE applications within a short span of time. Therefore a method/procedure to fold the airbag efficiently is of utmost importance. In this study the RRAB (Roof Rail AirBag) folding is carried out in LS-PrePost ® by DynFold option. It is purely a simulation based folding technique, which can be solved in LS-DYNA ® . In this paper we discuss in detail the RRAB folding process and tools/methods to make this effective. The objective here is to fold the RRAB to include modifications in the RRAB, efficiently and realistically using common analysis tools ( LS-DYNA & LS-PrePost), without exploring a third party tool , thus reducing the turnaround time.

• Roof-Crush Analysis of the Volvo XC40 using the Implicit Solver in LS-DYNA

  A. Jonsson (DYNAmore Nordic), M. Carlberg (ÅF/Volvo Cars (Consultant), T. Eriksson (Volvo Cars)

  During the development process of a new platform or car model, each design iterate is subjected to a large number of load cases, both dynamic as well as static. At Volvo Car Corporation, this process is almost entirely carried out using virtual testing by finite element analysis. The amount of physical prototypes is reduced to a minimum, and in many cases physical testing is limited to the component or sub-assembly level. Still, the final design must pass a number of physical tests and legal requirements, where roof crush is an important test of the structural integrity of the cab. The purpose of the FMVSS roof crush test is to “reduce deaths and injuries due to the crushing of the roof into the passenger compartment in rollover accidents” [6]. At Volvo Car Corporation, occupant safety is a fundamental element in all development projects since the start of the company, and the Volvo XC40 received a 5-star rating when tested by Euro NCAP [7]. The roof crush resistance is important with relation to safety in case of a roll-over accident, since the structural integrity of the car body makes the final line of defense, but many safety systems will interact in this case, from driver assist systems to electronic stability systems and restraint systems. The roof crush test will induce high stresses in many structural parts of the car body, for example the A-, B- and C-pillars, window frame and roof. This means that the analysis must be carried out meticulously, since the roof strength requirement may set design limits for many structural parts. Also new design concepts, such as composite roof panels or panorama glass roofs, imply new challenges for the roof crush analysis. The testing procedure according to FMVSS 216 [6] is specified as quasi-static (the time to complete the test is minimum 10, maximum 120 seconds), but has traditionally been run in explicit LS-DYNA in only a fraction of this time. From this viewpoint the roof-crush load case would be a typical application of implicit analysis, allowing the simulation of the test to get closer to the real test procedure. As a part of the ongoing method development work, it was decided to evaluate also the implicit technique, using the Volvo XC40 as a benchmark case. A previous study [5] indicated that it is possible to re-use FE-models originally created for crash load cases also for quasi-static load cases using the implicit solver in LS-DYNA with a reasonable modification effort. A previous study on implicit roof-crush analyses in LS-DYNA [1] indicated good correlation to explicit analyses, as well as reasonable performance with respect to solution time. Also, the publicly available examples [2][3] of implicit roof-crush analyses served as great inspiration in the present work.

• Running Jet Engine Models on Thousands of Processors with LS-DYNA Implicit

  R. Lucas, C. Ashcraft, R. Grimes, F.-H. Rouet (LSTC), J. Dawson, T.-T. Zhu (Cray), E. Guleryuz, S. Koric (NCSA), J. Ong, T. Simons (Rolls-Royce)

  Only time and resource constraints limit the size and complexity of the implicit analyses that LS-DYNA users would like to perform. Rolls-Royce is an example thereof, challenging its suppliers of computers and mechanical computer aided engineering (MCAE) software to run ever larger models, with more physics, in shorter periods of time. This will allow CAE to have a greater impact on the design cycle for new engines, and is a step towards the long-term vision of digital twins. Towards this end, Rolls-Royce created a family of representative engine models, with as many as 66 million finite elements. Figure 1 depicts a cross-section of the representative engine model.

• Rupture Modeling of Spot Welds Suitable for Crash FE Analysis in Vehicle Development Process

  Koushi Kumagai, Masakazu Shirooka, Jirou Ohachi, Toshirou Ogawa - Toyota Motor Corporation

  This paper describes the development of rupture modeling of spot welds suitable for crash FE analysis in vehicle development process. The authors presented a detailed spot weld rupture model called ‘spider web model’ in Toyota and confirmed that it closely correlates with actual full vehicle crash test results. Although, the spider web model is accurate, extensive effort is required to construct the model. Also, the spider web model can only simulate the nugget pullout mode of spot weld rupture and it cannot simulate the nugget fracture mode observed in the ultra high strength steels. Many investigations have been conducted on spot weld rupture modeling using mesh free connection which is suitable for vehicle development process. However, these models have not been validated with a full vehicle level test results. A spot weld rupture model using beam element and mesh free connection, which can simulate both nugget pullout and nugget fracture mode of spot weld rupture, has been developed. Full vehicle level FE analysis is conducted to confirm the prediction accuracy of developed spot weld rupture model. Results show that spot weld rupture locations and number of ruptured spot welds closely correlate with actual crash test results.

• S.P.H. : A SOLUTION TO AVOID USING EROSION CRITERION?

  Céline GALLET - ENSICA, Jean Luc LACOME - DYNALIS

  A new particle element has been added to LS-DYNA. It is based on Smoothed Particle Hydrodynamics theory. SPH is a meshless lagrangian numerical technique used to modelize the fluid equations of motion. SPH has proved to be useful in certain class of problems where large mesh distortions occur such as high velocity impact, crash simulations or compressible fluid dynamics. First, the basis principles of the SPH method will be introduced. Then, the model of perforation of a bullet through a thin plate will be presented. Two models are realised: one is made of lagrangian brick elements only, and the second one uses SPH elements for the plate. Finally, a discussion is proposed on the different methods used to deal with the penetration problem.

• Safety Analysis of the New Actros Megaspace Cabin According to ECE-R29/02

  Horst Raich - DaimlerChrysler AG

  During the development of truck cabins the safety of the driver and the front seat passenger in an accident is considered. The cab must be designed in such a way that in an accident a sufficient survival space is guaranteed. The legal requirements of cabin safety are fixed in Europe in the regulation ECE-R29. In order to reduce the number of iteration loops during the development process, a computational simulation method for the load cases roof strength test, front impact test and rear wall strength test of the ECE-R29 was introduced. The explicit finite element program LS-DYNA was used for that purpose. The deformations of the driver‘s cab and the loads of the individual components within the elastic and plastic range of the material behaviour can be determined before the first tests are carried out. These tests can then be limited to a minimum by the numeric simulation. In this paper, the application of this numerical method by the example of the new of ACTROS Megaspace cab is presented and compared to the results from the acceptance test according to ECE-R29.

• Safety Assessment and Multi-Objective Optimization of a Paratransit Bus Structure

  Cezary Bojanowski - Argonne National Laboratory, Ronald F. Kulak - RFK Engineering Mechanics Consultants

  Paratransit buses are used in the U.S. as a complementary service for regularly scheduled routes and are usually designed to transport disabled passengers in their wheelchairs. Paratransit buses consist of custom passenger compartments mounted onto separate cutaway chassis--usually built by reputable manufacturer like Ford or GM-- by a secondary manufacturer called a “body builder”. The lack of dedicated national crashworthiness standards, along with different construction methods used by paratransit fleet manufacturers, can result in a wide variance of passenger compartment structural strength. To ensure adequate crashworthiness performance, in August 2007 the Florida Department of Transportation (FDOT) introduced a standard stipulating that newly acquired buses must be tested for rollover and side impact conditions. The rollover test is performed using a tilt table test according to UN-ECE Regulation 66. The side impact test involves the impact of a bus by a common SUV or pickup truck. In the current study, a detailed FE model of a paratransit bus was used to perform LS-DYNA® explicit simulations of both rollover and side impact testing procedures per FDOT standard. LSTC IIHS solid movable barrier was adapted for the side impact test. Based on the results, the safety level of the bus was assessed. Subsequently, the response of the bus structure in the two impact scenarios together with the total mass were used as three separate objectives in a trade-off optimization study within LS-OPT®. The Pareto solutions were identified and presented using the newly implemented Hyper-Radial Visualization method in LS-OPT. The simulation results show that the original bus design would pass the FDOT testing procedure. However, appropriate redistribution of the mass can noticeably increase its strength.

• Safety Modeling of Lithium-ion Batteries under Mechanical Abuse

  Jie Deng, Min Zhu, Chulheung Bae, Theodore Miller, Ford Motor Company, Research and Innovation Center, Dearborn, Michigan 48124;, Pierre L’Eplattenier, Sarah Bateau-Meyer, Livermore Software Technology Corporation, Livermore, California 94551

  Lithium-ion batteries are one of the main energy storage devices in electrified vehicles. As their capacity and energy keep growing to meet the demand of longer driving range, their safety has become a primary concern due to their high energy and power density nature. Previously, abuse tests have been conducted to detect the failure conditions of lithium-ion batteries, but these tests can be expensive and time consuming. As such, computational modeling has played a more and more important role in evaluating battery responses under various abuse conditions. Here we present a multi-physical model for battery safety that is able to predict coupled mechanical, thermal, electrical and electrochemical responses of batteries using LS-DYNA®.

• Saving Calculation Time for Electromagnetic/ Mechanical/Thermal Coupled Simulations by Using the New EM 2D/3D Capabilities.

  Iñaki Çaldichoury, Pierre L‘Eplattenier (LSTC)

  LS-DYNA ® is a general purpose explicit and implicit finite element program used to analyse the non-linear dynamic response of three-dimensional solids and fluids. It is developed by Livermore Software Technology Corporation (LSTC). An electromagnetism (EM) module has been added to LS-DYNA for coupled mechanical/thermal/electromagnetic simulations, which have been extensively performed and benchmarked against experimental results for Magnetic Metal Forming (MMF) and Welding (MMW) applications. These simulations are done using a Finite Element Method (FEM) for the conductors coupled with a Boundary Element Method (BEM) for the surrounding air, hence avoiding the need of an air mesh. More recently, a 2D axisymmetric version of the electromagnetic solver was introduced for much faster simulations when the rotational invariance can be assumed. In many MMF and MMW applications though, the rotational invariance exists only for part of the geometry (typically the coil), but other parts (typically the workpiece or the die) may not have this symmetry, or at least not for the whole simulation time. In order to take advantage of the partial symmetry without limiting the geometry to fully symmetric cases, a coupling between 2D and 3D was introduced in the EM. The user can define the parts that can be solved in 2D and the ones which need to be solved in 3D and the solver will assume the rotational invariance only on the 2D parts, thus keeping the results accurate while significantly reducing the computation time. In this paper, the coupling method will be presented along with benchmarks with fully 3D and fully 2D simulations, comparing the accuracy of the results and the simulation times.

• Scalability of Implicit LS-DYNA® Simulations Using the Panasas® PanFS® Parallel File System

  Bill Loewe (Panasas, Inc.)

  As HPC continues its growth with Linux clusters using multi-core processor architectures, the I/O requirements further increase with higher-fidelity CAE modeling and workflow demands. This paper examines the parallel scalability characteristics of LSTC’s Finite Element Analysis software LS-DYNA for up to 288 processing cores for implicit mechanics simulations that have high I/O demands. The motivation was to quantify the performance and scalability benefits of parallel I/O in FEA software using a parallel file system, compared with both local storage and conventional NFS for implicit mechanics cases. This study was conducted on a Linux Intel Xeon cluster with a Panasas PanFS parallel file system and using a benchmark input provided by Roger Grimes from LSTC. For this study, relevant models used were based on current customer practice to demonstrate that LS-DYNA with parallel I/O can show a significant performance advantage and corresponding reduction in job overall time for advanced implicit simulations.

• Scalability of LS-DYNA on SGI Systems

  Roger Chu, Guangye Li - SGI

  In parallel computation, the scalability of the application software is critical. It is especially important when large number of processors are used. In this paper, we present the scalability results of LS-DYNA on the SGI multiprocessor computer systems. Furthermore, since MPP- DYNA is a domain decomposition based software, data partitioning algorithms play an important role in the scalability of the code. We will show in this paper that for some car crash models, special data partitioning techniques may improve the scalability significantly.

• Scalability Study of Particle Method with Dynamic Load Balancing

  Hailong Teng, Livermore Software Technology Corp.

  We introduce an efficient load-balancing algorithm for particle method (Particle Blast method and Corpuscular Particle method) in LS-DYNA®. Load-balancing is achieved by dynamically adaptively using RCB to evenly distribute workload to processors. Numerical tests demonstrated that with reformulated parallel scheme, for PBM, the speedup for an airblast problem can be 20~30 times or more when using 128~192 cores; for CPM, several times speed up can be achieved for a curtain airbag simulation.

• Scaling LS-DYNA on Rescale – HPC Cloud Simulation Platform

  J. Poort, I. Graedel (Rescale)

  Engineering and science simulations demand an increasing amount of computing resources. The majority of those resources consist of high performance computing (HPC) hardware, which are adaptable and highly efficient for running simulation software. Enterprises strive to create a lean and agile IT structure that both meets the current and unanticipated future needs of the various internal teams — without creating a cost structure that is unsustainable or disconnected from justifiable activities.

• Scaling Study of LS-DYNA MPP on High Performance Servers

  Youn-Seo Roh - Sun Microsystems, Inc.

  With LS-DYNA MPP, scalable SolarisTM operating system and the MPI library, Sun Microsystems’ StarfireTM server proved to be capable of producing a scalable solution for large-scale automotive crash simulation problems. It was found that a proper decomposition plays a significant role in achieving optimal scaling results for large-model, computation- intensive runs. Also, a large amount of external cache memory on the Starfire SMP server was found to be crucial for optimal runtime performance. With proper decomposition, a Starfire server was able to achieve 30X speedup and 93% efficiency with 32 processors in the simulation run of the NCAC Neon model consisting of 270,000 elements. Version 940.2a of LS-DYNA MPP showed good repeatability over largely different numbers of processes. It also displayed an exact repeatability on different runs when the command setting and number of processes are kept constant.

• Scatter Analysis of Crash Simulation Results Enabled by Data Compression

  Clemens-August Thole, Rodrigo Iza-Teran, Rudolph Lorentz, Helmut Schwamborn - Fraunhofer Institute for Algorithms and Scientific Computing

  In crash simulation, small changes of the model or boundary conditions may result in substantial changes of the simulation results. For the Neon test case [3], small variations of the barrier position result in substantial scatter of the intrusion. Detailed investigations of several models have shown that in some cases numerical effects might be responsible for the scatter in the results. In most cases, however, the instable behaviour of the simulation results is caused by bifurcations. These bifurcations result from numerical algorithms or are a feature of the car design. In the Neon model the scatter is a result of the interaction between the axle and the engine block. DIFF-CRASH1 is a tool, which allows one to measure scatter and to trace this scatter back to its origin. It allows the engineer, to understand the mechanisms of propagation and amplification of scatter during the crash itself as a basis for the improvement of the stability of the car design. For this analysis, DIFF-CRASH uses the complete result files of several simulation runs with a fine time resolution of the states. Storing these result files requires a substantial amount of disk space. FEMzip2 allows the reduction of this disk space by a factor of between 5 and 10. One can then store not only key results but the complete result files from optimisation experiments which can also be used for stability analysis. In this paper we discuss the accuracy required by DIFF-CRASH for a precise analysis and its implication on the data compression performance of FEMzip.

• scFEMod – The New Preprocessor for Efficient Assembly and Model Validation

  Ove Sommer, Thomas Ertl - science+computing, Norbert Frisch, Dirc Rose - University of Stuttgart

  This paper presents a new preprocessor for the assembly of independently meshed car body parts. The assembly process gains more and more importance in the preprocessing of crash-worthiness simulations. It is desirable to take simulation results into consideration for construction decisions already in the early phase of the car development process. At this stage, CAD data unfortunately does not contain any information about constraints like spotwelds or adhesive bondings between substructures. This lack of data has to be resolved by the simulation engineer. We provide an adequate preprocessing tool for this purpose, called scFEMod. scFEMod supports the simulation engineer in effectively defining missing constraints such as point, surface, edge, or line links. All of these can be specified interactively with the mouse pointer. Hierarchical data structures guarantee quick and automatic flange detection so that the assembly process is significantly accelerated. Furthermore, scFEMod can be used to replace separately meshed car body parts by variants which then need to be adapted to the adjacent mesh structure. Subsequently, initial perforations and penetrations can be detected, visualized, and selectively removed. Sensor points can be positioned and oriented in order to compare simulation results with those of physical crash tests. scFEMod allows to distribute non-structural masses over all car body parts they are connected to. Finally, the proper assembly of the whole car body model can be validated.

• Script for Automated One Step Forming Analysis using LS-DYNA and LS-PrePost

  A. Nair, D. Bhalsod (LSTC)

  Mapping of metal forming data on metal parts for Crash Simulations helps to simulate the widely known effect of stiffer physical properties due to manufacturing processes. LS-Dyna® has enhanced the previously available capability to simulate one step analysis on metal parts and can use the existing finite element geometry taken from a full vehicle model. This method is quicker than running an incremental analysis for hundreds of parts which would take a considerable amount of time. This analysis is done manually one part at a time along with some necessary preprocessing. For this process to be useful in a full vehicle crash analysis, where multiple parts have metal forming data mapped, an automated process with minimal user interaction in model set up is required. A script was written to facilitate this method. This paper discusses the algorithm used to automate the set up process.

• Secondary Shocks and Afterburning: Some Observations

  Len Schwer (SE&CS)

  Air blast tests that included normally reflected pressure measurements by the University of Sheffield, provided evidence of the so called ‘secondary shock.’ This repeat test data provided an opportunity to explore the effect of the LS-DYNA afterburning model parameters on the time of arrival and magnitude of the secondary shock. While the measured pressure histories alone are insufficient to uniquely calibrate the afterburn model, this manuscripts attempts to illustrated the effect on the secondary shock of changing the four afterburn model parameters: 1. Start time for adding energy 2. End time for adding energy 3. Amount of energy to be added 4. Rate at which the energy is added, i.e. either linearly increasing or constant.

• Secondary Shocks and Afterburning: Some Observations

  Len Schwer (SE&CS)

  Air blast tests that included normally reflected pressure measurements by the University of Sheffield, provided evidence of the so called ‘secondary shock.’ This repeat test data provided an opportunity to explore the effect of the LS-DYNA afterburning model parameters on the time of arrival and magnitude of the secondary shock. While the measured pressure histories alone are insufficient to uniquely calibrate the afterburn model, this manuscripts attempts to illustrated the effect on the secondary shock of changing the four afterburn model parameters: 1. Start time for adding energy 2. End time for adding energy 3. Amount of energy to be added 4. Rate at which the energy is added, i.e. either linearly increasing or constant.

• Seismic Modelling of an AGR Nuclear Reactor Core

  Bruce Duncan,Berislav Kralj - Atkins

  The work concerns the seismic response of an Advanced Gas-cooled Reactor (AGR) core. An LS-DYNA finite element model has been developed that represents each graphite brick. The contact between the bricks and their keys has been modelled with non-linear coaxial spring/dampers allowing for limited free motion. The model is a three dimensional representation of all the core layers and a neutron shield, making use of a symmetry by only modelling half of each layer. Different layers and groups of bricks have been allocated different spring/damper properties in order to accommodate differing initial geometry and levels of irradiation flux exposure. The core’s restraint system has also been modelled. Bespoke programs have been developed in Visual Basic for Applications to automatically generate the key file used by LS-DNYA and deal with the post-processing of results files. Sensitivity studies were done to assess the effects of changing the magnitude of the event and the effects of irradiation on the bricks.

• Seismic Response of Baffled Liquid Containment Tanks

  Zuhal Ozdemir (University of Sheffield), Yasin Fahjan (Gebze Institute of Technology), Mhamed Souli (Université des Sciences et des Technologies de Lille)

  The failure of liquid storage tanks due to earthquake induced sloshing action of the liquid was extensively observed during many past major earthquakes. The destructive effects of sloshing can however be suppressed in a passive manner by introducing additional sub-structures such as baffles into tanks. The main aim of constructing these sub-structures is to alter the period of sloshing action beneficially and to increase hydrodynamic damping ratio. The main aim of this paper is to numerically quantify the effect of baffles on the response of 2D rigid tanks. In this paper, LS-DYNA program is chosen as a numerical analysis tool due to its high degree of flexibility. The numerical model is first verified using an existing numerical study in the literature and a strong correlation between reference solution and numerical results is obtained in terms of sloshing wave height. Following the verification of the numerical model, the hydrodynamic damping ratio of sloshing in a 2D rigid baffled tank is assessed for different baffle positions. Finally, a parametric study is carried out on 2D rigid tall and broad baffled tanks in order to assess the effect of baffle on the sloshing wave height under different earthquake motions.

• Selecting Material Models for the Simulation of Foams in LS-DYNA

  Brian Croop,Hubert Lobo - DatapointLabs

  Foams are multi-phase materials that exhibit dramatically different properties that depend on the matrix material as well as the pore microstructure. This additional degree of freedom from the presence of the gas phase makes material modelling for foams a difficult matter. LS-DYNA offers a variety of material models, each with capabilities designed to capture the unique behaviour of a different types of foam. The selection of the correct material model depends to a large extent, on the observed behaviour of the foam during the test. Other factors will include the actual situation under simulation, which becomes important for highly non-linear materials, where a single material model often cannot capture all the dependencies, forcing a localized material calibration. The material calibration itself is not easy because of the lack of set procedures for characterization. Previous research has devoted a lot of effort to enhancing these material models to improve their capabilities as well as to make them easier to use. In our current work, we seek to lay down a framework to help us understand the different behavioural classes of foams. Following a methodology that we previously applied to plastics, we will then attempt to propose the right LS-DYNA material models that best capture these behaviours. Guidelines for model selection will be presented as well as best practices for characterization. Limitations of existing material models will be discussed.

• Selecting Material Models for the Simulation of Foams in LS-DYNA

  Brian Croop,Hubert Lobo - DatapointLabs

  Foams are multi-phase materials that exhibit dramatically different properties that depend on the matrix material as well as the pore microstructure. This additional degree of freedom from the presence of the gas phase makes material modelling for foams a difficult matter. LS-DYNA offers a variety of material models, each with capabilities designed to capture the unique behaviour of a different types of foam. The selection of the correct material model depends to a large extent, on the observed behaviour of the foam during the test. Other factors will include the actual situation under simulation, which becomes important for highly non-linear materials, where a single material model often cannot capture all the dependencies, forcing a localized material calibration. The material calibration itself is not easy because of the lack of set procedures for characterization. Previous research has devoted a lot of effort to enhancing these material models to improve their capabilities as well as to make them easier to use. In our current work, we seek to lay down a framework to help us understand the different behavioural classes of foams. Following a methodology that we previously applied to plastics, we will then attempt to propose the right LS-DYNA material models that best capture these behaviours. Guidelines for model selection will be presented as well as best practices for characterization. Limitations of existing material models will be discussed.

• Self-piercing riveting

  Andre Stühmeyer - CAD-FEM GmbH

  Overview • The self piercing riveting process • FE analysis of the joining process – Large deformation – Material failure – 2D remeshing approach – 3D remeshing approach • Comparison with experiments • Process optimization with FEA • Summary

• Sensitivity of Particle Size in Discrete Element Method to Particle Gas Method (DEM_PGM) Coupling in Underbody Blast Simulations

  Venkatesh Babu, Kumar Kulkarni, Sanjay Kankanalapalli, Ravi Thyagarajan (RDECOM, TARDEC)

  In this paper, the capability of two methods of modelling detonation of high explosives (HE) buried in soil viz., (1) coupled discrete element & particle gas methods (DEM-PGM) and (2) Arbitrary Lagrangian-Eulerian (ALE), are investigated. The ALE method of modeling the effects of buried charges in soil is well known and widely used in blast simulations today [6]. Due to high computational costs, inconsistent robustness and long run times, alternate modeling methods such as Smoothed Particle Hydrodynamics (SPH) [7] and DEM are gaining more traction. In all these methods, accuracy of the analysis relies not only on the fidelity of the soil and high explosive models but also on the robustness of fluid-structure interaction. These high-fidelity models are also useful in generating fast running models (FRM) useful for rapid generation of blast simulation results of acceptable accuracy [8-14]. In this paper, the effect of sensitivity of particle size in the performance of the DEM_PGM blast simulation is compared to that of the ALE blast simulation method. The main focus of this study is to understand the strengths of DEM_PGM and identify the limitations/strengths compared to the ALE method. Discrete Element Method (DEM) can model individual particle directly, and displace independently which is based on Cundall & Strack [1] A 2m x 2m x 2m volume is filled with ALE elements of 10mm side length. Three sets of ALE-equivalent DEM models are created using 3mm, 4mm and 5mm radius spheres. High explosive TNT is buried 50 mm deep in these three DEM soils and modeled as particles using PARTICLE_BLAST. Each of the 3 sets of DEM are analyzed for 100k, 250k, 500k and 750k TNT particles to understand the sensitivity of the DEM_PGM coupling and how the soil impulse, kinetic energy and translational energy are affected. This analysis has been extended to evaluate the TARDEC generic hull (GH) structural performance and compared to ALE method. Results show that DEM_PGM method reduces the computational time significantly when compared to the ALE method, and soil, a granular material by nature, can be well represented by fine particles in its discontinuous form.

• Sensitivity Study of Self-Piercing Rivet Insertion Process Using Smoothed Particle Galerkin Method

  Li Huang, Garret Huff, Andrey Ilinich, Amanda Freis, Shiyao Huang, George Luckey (Ford Motor Company), Youcai Wu (Livermore Software Technology Corporation)

  Self-piercing rivets (SPR) are efficient and economical joining elements for automotive body structures manufacturing. The Smoothed Particle Galerkin Method has been initially proven as a potentially effective way to assess the SPR joining process. However, uncertain CAE parameters could result in significant mismatches between the CAE predictions and physical tests, and therefore the sensitivity study on critical model parameters is important to guide the modeling of the SPR insertion process. In this paper, a meshfree, i.e., Smoothed Particle Galerkin (SPG), method was applied to the simulation of the SPR insertion process with LS DYNA®/explicit. The severely deformed upper sheet was modeled using the SPG method with activated bond failure, while the rest of the model was modeled using the traditional finite element approach. An extensive sensitivity study is conducted to understand the effect of a set of model parameters. This work provides a foundation for CAE model calibration for the SPR insertion process using SPG.

• Sequential drop test simulations through automated process in Workbench LS-DYNA

  Yury Novozhilov, Ulrich Stelzmann

  Modeling drop tests of various goods has always been one of the classic problems for explicit structural dynamics. Current requirements for such tests often require the consideration of multiple sequential impacts, such as the procedures described by the International Safe Transit Association. CADFEM is investigating the possibilities of automating such sequential drop tests in the Workbench LS-DYNA environment. With the automated calculation of sequential drop tests, these can be integrated into optimization cycles.

• Sequential Optimization & Probabilistic Analysis Using Adaptively Refined Constraints in LS-OPT®

  Anirban Basudhar, Imtiaz Gandikota (Livermore Software Technology LLC, Ansys Group), Katharina Witowski (Dynamore GmbH)

  This paper presents some of the sequential optimization and probabilistic analysis methods in LS-OPT with particular emphasis on the use of classifiers for accuracy and efficiency improvement. Classifiers were first introduced in LS-OPT 6.0 for the handling of constraints. This paper provides a review of the basic classification-based constraint handling method and its applications and advantages for specific types of problems. Additionally, the application of classifiers is extended to adaptive sampling using EDSD (explicit design space decomposition) sampling constraints in LS-OPT 6.1. The different adaptive sampling options and approaches are presented through the examples. Another aspect of this paper is the extension of the probabilistic analysis method in LS-OPT from single iteration to sequential. The sequential analysis can be performed with or without EDSD sampling constraints, but sampling constraints, if used, are can guide the samples adaptively to important regions. Although the EDSD sampling constraints are defined using support vector machine (SVM) classifiers, the adaptive samples are useful in enhancing the constraint boundary accuracy even if it is defined using metamodels.

• Session7_Paper2_Abstract.pdf
• Setting up a Hot Stamping Simulation considering Tool Heating with OpenForm

  K. Kassem (GNS)

  The steadily growing requirements regarding the carbon footprint of vehicles has motivated the deployment of quenching (hot stamping) as a promisingly manufacturing process for lightweight car bodies in the series production of structural components. Very high part stiffnesses as well as formabilities can be achieved by means of this quenching process with significantly less forming energy and material consumption. This sets new standards both in vehicle safety and vehicle crash performance as well in sustainable and resource-saving mass production of car body components.

• Shape Adaptive Airfoils for Turbomachinery applications: Simulation and Optimization

  Tobias Müller, Martin Lawerenz - University of Kassel

  Smart materials and smart structural concepts in flow control have the potential for significant impact on the design and performance of modern turbocompressors. While the benefits of an airfoil whose geometry is variable were investigated in detail in the area of adaptive wings for airplanes, this is a new field for the application in turbomachines. The main focus is on simulations of novel flow control concepts to allow a structural ’morphing’ and thus changing the aerodynamic characteristic of the airfoils. LS-DYNA 970 Implicit is used for the calculations. Additionally, shape optimiziations are performed using LS-OPT in conjunction with a parametric mesh generator.

• SHAPE OPTIMIZATION FOR HEAD AND KNEE IMPACT FEATURING ADAPTIVE MESH TOPOLOGY AND A DISCRETE VARIABLE

  Nielen Stander, Mike Burger, Suri Balasubramanyam - Livermore Software Technology Corporation, Sharath Varadappa - Quantum Consultants, Inc., Detroit

  A successive linear response surface method (SRSM) is applied to the shape optimization of vehicle crashworthiness problems involving knee and head impact. A preprocessor is used to parameterize the geometric model and mesh topology. An upper limit on the element size is used as a criterion for the mesh adaptivity. Simulation is conducted using the explicit dynamic analysis method. The study demonstrates the effectiveness of adaptive meshing and simulation-based shape optimization in problems of complex behavior such as crash simulation.

• Shape Optimization of a Vehicle Crash-box using LS-OPT

  Marcus Redhe, Larsgunnar Nilsson - Engineering Research Nordic AB, Fredrik Bergman - Saab Automobile AB, Nielen Stander - LSTC

  The aim of this project is to optimize the geometry of a crash-box due to impact at low velocity impact. The optimization problem is solved in LS-OPT, using Neural Networks as meta-model. The Neural Networks meta-model has been evaluated on a small test example and it shows remarkable good approximation of the responses. The geometry was parameterized using HyperMorph. In addition to the geometry parameters, the sheet thickness and the material quality of the crash-box and the bumper-beam were also varied. The FE-model used is a passenger car from Saab Automobile. The objective is to minimize the mass of the crash-box subjected to two deformation constraints and a constraint on the maximum plastic strain in the main crash-rail, which is positioned behind the crash-box. During the optimization procedure, unfortunately, the crash-rail shown to be too weak and it need to be strengthening up using an extra component in the weak section of the crash-rail. Consequently no solution that fulfilled all constraints was found. However, LS-OPT reduced the mass of the component with 20 % and in the same time reduced the sum of all constraint violations with 50 %. Only the plastic strain constraint was violated after five iterations. The meta-modelling technique using Neural Networks showed good results with small surface approximation errors.

• SHAPE OPTIMIZATION OF CRASHWORTHY STRUCTURES

  D. J. Eby, R. S. Sidhu - Applied Computational Design Associates, Inc., R.C. Averill, E.D. Goodman - Department of Mechanical Engineering

  Crashworthiness problems, which are highly dynamic and nonlinear, do not lend themselves well to classical gradient optimization techniques. Evolutionary-based design approaches that employ a form of guided stochastic search algorithm have been successfully applied to these problems. While many design optimization approaches are limited to a small number of continuous design variables, the approach described here can productively search over hundreds at a time. The power of classical evolutionary algorithms can be increased by allowing flexible design variable decomposition and incorporating classical local optimization methods and/or by embedding them within adaptive agents, which communicate but work semi-independently on a common problem. The authors have developed a system that allows for flexible design variable decomposition while combining evolutionary algorithms with local optimization. Within this approach, autonomous agents break down a problem hierarchically, using problem-specific divide-and-conquer rules to organize design variables and design criteria into a set of highly decomposed, overlapped relationships. These agents simultaneously search a discretized design space at various levels of resolution and use different design variable representations, performance measures (combinations of objectives and constraints), and local search methods. The agents exchange information about the decomposed solution space with each other, helping them jointly to satisfy multiple constraints and objectives. This technology has been implemented into a software code called HEEDS (Hierarchical Evolutionary Engineering Design System), which can be run on a single processor or in a networked computing environment, including clusters of personal computers or simple networks of workstations. Using LS-DYNA explicit as the finite element solver within the HEEDS optimization environment, this process has been applied to several automotive lower compartment rail designs, resulting in significant gains in performance along with up to 20% reductions in mass compared to baseline rails designed by experienced engineers. An example application of this method is described herein.

• Shape Optimization Of Instrument Panel Components For Crashworthiness Using Distributed Computing

  Alex Akkerman , Ravi Thyagarajan - Ford Motor Company,, Mike Burger, Nielen Stander - Livermore Software Technology Corp.,, Bob Kuhn, Hrabri Rajic - Kuck & Associates, Inc.

  The ability to quickly design new vehicles with optimal crashworthiness is a goal of automotive manufacturers. This paper takes steps towards that goal by automating manual design iterations. The crashworthiness of an instrument panel was enhanced using LS-OPT and LS-DYNA. It is shown that: • LS-OPT can modify the shape of non-styled parts in the instrument panel in order to • The design was generated several times faster than with manual methods. LS-OPT • The dramatic increase in the size of the design space caused by shape optimization • The cost of obtaining these designs can be reduced by using distributed computing to enhance its crashworthiness by using a parametric preprocessor, e.g. TrueGrid®. generated and executed LS-DYNA runs without need for manual result analysis. was managed efficiently by LS-OPT. explore the design space on workstations which would otherwise be underutilized.

• Shape Optimization with LS-DYNA® Suite For MDO (Multidisciplinary Design Optimization)

  Ryo Ishii, JSOL;, Masayoshi Nishi, Nihon Emsco Co. Ltd.

  LS-DYNA has been able to optimize several different calculations to meet each criterion with LS-OPT® freely. In previous year, we showed MDO (Multidisciplinary Design Optimization) would be great powerful solution that LS-DYNA suite including LS-OPT and LS-PrePost® would be able to solve crucial problem during development of product. In this study, we are trying shape optimization to solve trade-off which occurs in the process of product development much frequently. In order to optimize design parameter such as shape, bead and so on, the tool changing product shape automatically is needed. On the other hand, LS-PrePost becomes very powerful that morphing function has been integrated. The challenge in this study is to connect LS-PrePost to LS-OPT and do a shape optimization.

• Sheet Metal Forming in a Virtual Reality Environment using LS-DYNA and Neural Networks

  Ashwini S. Gokhale - Wichita State University

  Manufacturing process simulation using finite element techniques has immensely contributed to ensuring the success of concurrent design methodologies. However, Finite Element Methods (FEM) is computationally expensive and consequently unsuitable for design and manufacturing optimization in a production environment. In this research, a coupled Artificial Intelligence (AI) and FEM technique was developed to simulate and predict process response to changes in part design. Generic process models of part families are developed using Artificial Neural Networks (ANNs) and FEM. The generic models are used to predict the response of the manufacturing process to variations in geometric, material and process parameters, in real time. The predicted results are graphically displayed in a Virtual Reality environment. Standalone software VRForm was developed based on this methodology. VRForm can be used to optimize component, tool and process designs.

• Sheet Metal Forming Simulation and Real World Tooling

  Matt Clarke - Continental Tool and Die, Jeanne He - Forming Simulation Technology LLC

  In a modern day draw simulation; our objective has always been to verify the formability of the deformed blank. We then utilize the output of the simulation to ascertain the forces required to form the part. Little time is spent attempting to verify if our design for the die is capable of reproducing these results. Most simulation assumes the tools are rigid. The real expertise comes when you can reproduce that scenario in an actual tool that makes parts in a consistent manner. This study follows a real world die development and build project, where the initial tryout was completely different from the simulation results, binder deformation has played a key role which differs the simulation results in which all tools are assumed to be rigid. Further simulation with a flexible binder has been performed, also compared to the real world solutions that were developed to make a good part. This study also provides valuable information for exploring the next generation of forming simulation needs. A major advance in simulation technology would be to answer the question of how simulation can compensate for these inadequacies. Through this study, it is clear that optimization analysis for various tooling needs to be shortened the tooling process time and reduction of the cost is an obvious trend in the near future.

• Sheet Metal Forming Simulation with IGA in LS-DYNA®

  Stefan Hartmann, DYNAmore GmbH, Stuttgart, Germany;, David J. Benson, Liping Li, Attila P. Nagy, Livermore Software Technology Corporation, Livermore, CA, USA

  In the last few years, numerous research work has been devoted to Isogeometric Analysis (IGA). IGA is a finite element technology in which computer-aided design (CAD) geometric description is invoked to perform numerical analysis. The most widely used mathematical description in CAD is non-uniform rational B-splines (NURBS) and therefore NURBS-based shell and solid finite elements have been implemented into LS-DYNA.

• Sheet Metal Forming: Spring-back of hydro mechanical deep drawn parts

  Jens Buchert, Herbert Bauer - University of Applied Sciences, Germany, David K. Harrison, Anjali De Silva - Glasgow Caledonian University, UK

  Active hydro mechanical forming (AHMF) has been developed in order to meet the demand of the automotive industry for economical production of sheet metal parts with more individuality in small lot sizes. Conventional deep drawing of automobile parts which have large outer surface areas (such as roofs, doors and hoods) leaves them with a very small dent resistance. This is caused by the low deformation degree in the middle of the part. This low component stiffness has a negative effect on the crash resistance of vehicles. By using the AHMF technology a consistent plastic strain distribution can be brought into the part and therefore its stability will be improved. Within the design of conventional deep drawing tools the spring-back of a part is well understood because of the long experience with the process and its influence on the stress distribution inside the deformed part. In AHMF, as with any new process, the spring-back phenomenon is still under investigation. There are a considerable number of parameters to control in order to regulate the stress distribution and the shell thickness, which leads to more spring-back possibilities. This paper presents a simulation of spring-back in AHMF to find an efficient method of tool design and to generate the optimum process parameters, in the prototyping or later production. The FEM simulation is based firstly on the validation of the results of the AHFM process given by the mathematical calculation with the computer generated model. Secondly, spring-back simulation is introduced to see the influence of pressure curves and the blank holder forces or the parameters of the pre-bulging step. The quality of the FEM simulation is verified using practical applications in the automotive industry.

• Shell Models with Enhanced Kinematics for Finite Elements in Sheet Metal Forming Simulations

  T. Willmann, M. Bischoff (University of Stuttgart)

  Beyond the shell model of Reissner and Mindlin, which is available in LS-DYNA® for example in shell ELFORM=2/16, there have been many developments in the field of 3d-shell models in recent years [1]. 3d-shell models can be beneficial in sheet metal forming simulations because they allow for three-dimensional stress states. 3d-shell elements are available in LS-DYNA®, e.g. ELFORM=25. In the doctoral dissertation of Fleischer[2] it has been found that under certain conditions this element formulation suffers from an artificial stiffening effect. Although this finding dates back to 2009, this phenomenon has remained unexplained so far. In this contribution, the authors explain the reason for this stiffening effect and show a possibility to remove it. Moreover, an outlook on the development of higher order shell models for sheet metal forming simulation is given.

• SHIP STRUCTURES SUBJECT TO HIGH EXPLOSIVE DETONATION

  Mark Z. Vulitsky, Zvi H. Karni - John J. McMullen Associates

  Predicting the structural response of a naval vessel to a high explosive detonation is an important requirement in naval shipbuilding. Unfortunately, current analysis methods do not provide high level of confidence leading to the utilization of large structural design safety factors. As a result, ships are heavier and more expensive to construct and maintain than may actually be required. Moreover, more reliable predictions can support innovative structural configurations, which provide lower life-cycle costs with increased survivability. In the currently used approaches, pressure-time history is initially generated from empirical equations and/or test data, and then the time dependent pressure is applied to the structure. These approaches have many limitations and use various approximations. This paper highlights a numerical simulation procedure for the prediction of the effect of the detonation of high explosive compounds on steel structure. The dynamic simulation interfaces the blast wave predicted by the Jones-Wilkins-Lee (JWL) equation of state for high explosives (built-in the LS-DYNA equation of state library), with time dependent spatial response of the structure. The air surrounding the structure is modeled to represent the medium in which the blast propagates using the LS-DYNA multi-material elements. A linear polynomial equation of state is used to simulate the proper behavior of air. Several explosion tests with different configurations (internal and external) were conducted in order to quantify the effect of a detonation on different structurally representative test articles. It was established that the numerical simulation demonstrates good correlation with the empirical results.

• Shock Response Analysis of Blast Hardened Bulkhead in Naval Ship under Internal Blast

  S.-G. Lee, H.-S. Lee, J.-S. Lee (Korea Maritime & Ocean University), Y. Y. Kim, G. G. Choi (Korea Advanced Institute of Science and Technology)

  It is necessary to restrict the damage area for the enhancement of ship survivability under the internal blast of a Semi-Armor Piecing (SAP) warhead inside a ship’s compartment, and to develop design guidance and performance verification technique of Blast Hardened Bulkhead (BHB) for the protection of its damage diffusion to adjoining compartment and continuous flooding.

• Shock Wave Effect on Aluminium Foam

  M. Vesenjak, M. Borovinšek, Z. Ren - University of Maribor, Slovenia, S. Irie - Kumamoto University, S. Itoh - Okinawa National College of Technology

  The behaviour of aluminium foam under impact loading conditions and especially the shock wave propagation are still not well understood. The shock wave propagation through the cellular material structure under impact loading conditions has a significant effect on its deformation mechanism and therefore it is imperative to understand its effects thoroughly. The goal of this research was to investigate and examine the effects of shock wave propagation on aluminium foam. Additionally, the material and structural properties of pore- filled aluminium foam under impact loading conditions with particular interest in shock wave propagation and its effects on cellular material deformation have been studied. For this purpose experimental tests and explicit computational simulations of aluminium foam specimens inside a water tank subjected to explosive charge have been performed. Comparison of the results shows a good correlation between the experimental and simulation results.

• Short and Long Fiber Reinforced Thermoplastics Material Models in LS-DYNA

  S. Hartmann, T. Erhart, A. Haufe (DYNAmore), P. Reithofer, B. Jilka (4a engineering)

  In the last years the demand on weight reduction in the automotive industry has led to a strong interest for various composite applications. Due to the complexity of those usually highly anisotropic materials virtual product development is one of the key factors to understand the load carrying behavior of such parts. Furthermore enhanced CAE tools and models are necessary to ensure an efficient and robust product development.

• Short Introduction of a New Generalized Damage Model

  T. Erhart, F. Adrade (DYNAmore); P. Du Bois (Consultant)

  In LS-DYNA, several constitutive models exhibit properties that are based on Continuum Damage Mechanics (CDM) [1]. Associated isotropic or anisotropic stress degradation represents softening and failure behavior of metals (e.g. *MAT_104), composites (e.g. *MAT_221), polymers (e.g. *MAT_187), and other material types. As an alternative, sophisticated (e.g. stress state dependent) damage models such as GISSMO [2, 3] or DIEM [4] can be used as add-ons to a wide range of standard material models via *MAT_ADD_EROSION. With the release of LS-DYNA version R9, a new keyword *MAT_ADD_GENERALIZED_DAMAGE (MAGD) was added as a further step towards an even more versatile tool in this area. The primary idea was to provide non-isotropic (tensor type) damage with multiple independent damage variables. Users can define the entries of the damage tensor by functional input (*DEFINE_FUNCTION) to achieve maximum flexibility. The evolution of damage variables is driven by strain based values that can be determined in a number of ways. They can either be arbitrary history variables of the accompanying material model, or quantities derived from the plastic strain tensor. Therefore transformations of that tensor to the principal strain system or to the local system of material directions can be selected. Besides the possibility of using individual plastic strain tensor components as damage driving quantities, functional combinations of them are also allowed through the keyword *DEFINE_FUNCTION. For the damage evolution laws itself, the GISSMO approach can be used where corresponding input variables (such as stress state dependent failure strain, regularization, etc.) can be defined separately for each damage parameter. As a matter of fact, MAGD is a very flexible tool to incorporate non-isotropic damage into existing material models. The first successful application was done for aluminum extrusions, which show marked directional dependencies of failure strain [5]. This presentation will describe the underlying theory of MAGD, explain the various input options, and demonstrate its main functionalities using simple numerical examples.

• Side Curtain Airbag Folding Methodology

  Pablo Alberto Rodríguez Calzada, Hector Hernández Hernández, Alejandro García Pérez, Carlos Gómez González (Ford Motor Company)

  In recent years, CAE simulations have been substantially improved as a result of the growing need to achieve full vehicle developments in a shorter time span while also attending the demand of cost reduction in such developments. One of the most critical components regarding the passive safety systems of a vehicle is the Side Curtain Airbag, therefore the necessity to involve this critical component in an agile product development process becomes compulsory. Consequently, when the validation using numerical methods of such component is performed, a full deployment of the airbag is needed to be evaluated and analyzed, having as a key objective the monitoring of its dynamic behavior caused by the effect of interacting with nearby components. In view of the foregoing, the folding process of the airbag plays a key factor in its whole operation. This study describes a hybrid methodology to fold a Side Curtain Airbag by means of a geometrical and simulation-based routine, which can be defined entirely on LS-PrePost®, using the embedded tools in the occupant safety applications. This work aims to englobe the tools and steps followed in order to obtain, within a short period of time, a LS-DYNA® CAE model of the airbag, capable of representing efficiently and accurately a deployment, which might be used in early stages of numerical analysis for areas such as Interior Trim integrity and safe interaction. Using this CAE methodology, a new scope of problem-solving techniques originates. Applying the novel approach described in the preceding paragraph, a folding scenario could be useful to control the dynamics of the airbag in order to achieve a faster deployment in a certain zone, to avoid an undesired interaction with the interior trim of the vehicle, or to simply evaluate the aperture time of the system overall. All this adds up to a feasible cost reduction alternative to the most common techniques that involve modifying and adapting geometries including supplementary components, that impact directly in the prime cost of a vehicle.

• Side Impact Occupant Modeling Practices in Comparison to Test Results

  Skye Malcolm, Brian O’Hara, Craig Markusic, Bryant Whitcomb - Honda R&D Americas, Inc., Ram R. Songade - Altair Engineering, Inc.

  A methodology to obtain and estimate the second row dummy response during the FMVSS 214 Barrier Side Impact test is described. Because of the limited amount of space between the occupant and the car structure, it is challenging to manage and predict the energy distribution in the FMVSS 214 crash mode. Increasing use of Finite Element models provides an edge in product development and its use is increasing as development time is reducing. For increased correlation with the test and more realistic dummy response, several factors are important, including the effect of restraint systems and representation of interacting components. This paper describes a methodology by which the second row occupant injury can be well-correlated to the test and used to help enhance occupant protection during vehicle development. A commercially available SID-IIs dummy and a Moving Deformable Barrier from LSTC are used in this study.

• Side Member Crumple Section Simulation and Structural Optimization

  Taian Chen, Clive Chirwa, Wei Wang, M. Mao - The University of Bolton

  Energy absorbing structural component in a car front impact The study shows the energy management of the front end structure it’s stiffness, strength and crush mode as function of occupant load. A well designed front end structure will have loads well below the tolerance limit of actual injury criteria (FMVSS 208, ECE R94) Progressive tube axial crushing and s-shape tube bending are commonly used as energy absorbers This paper presents experimental and FE parametric study of side member energy absorption capability, its force characteristic and the collapse mechanism

• Sidewall Indentation and Buckling of Deformed Aluminum Beverage Cans

  Robert W. Bielenberg - University of Nebraska-Lincoln, Scott H. Magner - University of Nebraska-Lincoln, John D. Reid - University of Nebraska-Lincoln

  Previous research has demonstrated that finite element analysis can be used to predict the structural behavior of aluminum beverage cans including the buckling of the sidewall of the can. Buckling of a beverage container can occur when the lid is pressed on dented cans during assembly. The purpose of this research was to simulate the sidewall indentation and the buckling of aluminum cans with a deformed sidewall using LS-DYNA and validate the results through physical testing. Simulation of the sidewall indentation was done with an impacting sphere. Parameters investigated through simulation included the size of the impacting sphere, velocity of sphere, and impact height along sidewall of can. Results from this study are maximum and final can deflection, maximum and final energy absorbed by the can, and force deflection data. Simulation of the buckling of the deformed can was also performed. Results from the deformed can buckling model compared well with physical testing based on buckled geometry, buckling load, and external work to buckle. The deformed can model proved capable of accurately simulating the buckling of the deformed can.

• Sideways launching process of a ship using the Arbitrary-Lagrangian-Eulerian approach

  A. Ulbertus, M. Schöttelndreyer (thyssenkrupp Marine Systems), S. Ehlers (Hamburg University)

  The launching process of ships is always a critical event during its construction. Especially a sideways launching process can be challenging. Besides high loads on the ship’s hull structure at the impact with the water surface, the stability has to be checked carefully to prevent capsizing of the ship. The resulting maximum heeling angle is one of the most critical parameters during such a launching process. If the maximum heeling angle gets too high, the ship can capsize or higher openings (e.g. ventilations) can come in contact with the water resulting in flooding of compartments. Therefore, the movement of the ship and the loads at impact with the water surface have to be assessed as accurately as possible during the design of a ship, if a sideways launching process is planned.

• Similar part identification integrating machine learning approaches with a SDM workflow

  Uwe Reuter, Marcelo Pintado, Marko Thiele, Akhil Pillai, Florian Moldering

  Machine learning (ML) approaches for geometric part recognition have been evaluated with 3D automotive data in [1], where only one vehicle was used (Toyota Yaris with around 200 parts) and the exact match was tested, which means that the model was able to identify only the particular part shown regardless of the other classes (one-to-one match).

• Simple Input Concrete Constitutive Models: An Illustration of Brick Wall & Concrete Cylinder Perforation

  Leonard E. Schwer - Schwer Engineering & Consulting Services

  Analysts faced with making predictions that involve uncharacterized materials need to bound their results in a rational manner. For concrete materials, LS-DYNA® includes three simple input concrete material models that provide strength envelopes ranging from low, to intermediate, and high strength. Using a range of concrete strengths in numerical simulations is rational when little or no other information about the concrete is available. The typical system response quantity of interest (SRQ) in perforation studies is the exit velocity of the projectile. The simple input concrete models provide a range of concrete resistance to penetration that in turn produces a corresponding range of projectile exit velocities. Quantifying this possible range of exit velocities provides the decision maker with an assessment of what to expect in the field or laboratory for uncharacterized concrete targets. The use of multiple simple input concrete models to provide a range of exit velocities is demonstrated for a simple model of a brick wall, where no experimental data was available. To provide the reader with some indication how this approach can be used to compare predictions with laboratory data, the experimental and numerical results for a set of concrete cylinder perforations is provided.

• Simplified FE Simulation of Frontal Occupant Restraint Systems

  Richard Brown, David Coleman, Ian Bruce - Jaguar Land Rover

  A biofidelic flexible pedestrian legform impactor (Flex-PLI) has been developed by Japan Automobile Manufacturers Association, Inc. (JAMA) and Japan Automobile Research Institute (JARI). The Flex-PLI has good biofidelity as well as several knee ligament elongation measurement capabilities, three femur and four tibia bending moment measurement capabilities. For these reasons Flex-PLI is likely to be used for future pedestrian Global Technical Regulation. This paper introduces a finite element model of the Flex-PLI type GT for LS-DYNA and compares a full vehicle Flex-GT impact simulation with test. A very accurate vehicle model is needed to predict Flex- PLI injuries. In this paper, a detailed and correlated vehicle model was used. The Type GT is the 5th version of Flex-PLI and has almost the same structure and performance as final design type GTR. The Flex-PLI type GT LS-DYNA model was carefully created to ensure every important detail was included. Geometries, masses and material properties of all parts were reproduced from drawings and inspection of the real components. Connectivity and component interaction within the model was determined by thorough experiments. Accurate prediction of injury indices and kinematic behaviour was achieved by correlation to static and dynamic calibration tests. A fine mesh was used but reasonable calculation cost assured by imposing an analysis time step of 0.9 micro seconds.

• Simplified FE Simulation of Frontal Occupant Restraint Systems

  Richard Brown, David Coleman, Ian Bruce - Jaguar Land Rover

  A biofidelic flexible pedestrian legform impactor (Flex-PLI) has been developed by Japan Automobile Manufacturers Association, Inc. (JAMA) and Japan Automobile Research Institute (JARI). The Flex-PLI has good biofidelity as well as several knee ligament elongation measurement capabilities, three femur and four tibia bending moment measurement capabilities. For these reasons Flex-PLI is likely to be used for future pedestrian Global Technical Regulation. This paper introduces a finite element model of the Flex-PLI type GT for LS-DYNA and compares a full vehicle Flex-GT impact simulation with test. A very accurate vehicle model is needed to predict Flex- PLI injuries. In this paper, a detailed and correlated vehicle model was used. The Type GT is the 5th version of Flex-PLI and has almost the same structure and performance as final design type GTR. The Flex-PLI type GT LS-DYNA model was carefully created to ensure every important detail was included. Geometries, masses and material properties of all parts were reproduced from drawings and inspection of the real components. Connectivity and component interaction within the model was determined by thorough experiments. Accurate prediction of injury indices and kinematic behaviour was achieved by correlation to static and dynamic calibration tests. A fine mesh was used but reasonable calculation cost assured by imposing an analysis time step of 0.9 micro seconds.

• Simplified Integrative Simulation of Short Fibre Reinforced Polymers under Varying Thermal Conditions

  C. Witzgall, Prof. S. Wartzack (University of Erlangen-Nürnberg)

  The use of injection moulded, short fibre reinforced structural parts in vehicle design is increasing due to their low density and outstanding mechanical properties. As the distribution and orientation of fibres within the components are heavily dependent on the moulding process, product devel-opers do well to take process simulations into consideration before performing anisotropic struc-tural analyses. To enable the use of these integrative simulations within early design stages, a simplified approach has been developed by SCHÖPFER and extended by GRUBER/WARTZACK. It considers the material's anisotropy by using the fibre orientation data gained from the injection moulding simulation.

• Simplified modeling of pouch cells under different loadings

  A. Trondl, D.-Z. Sun, S. Sommer (Fraunhofer IWM)

  Due to increasing requirement on the reduction of CO2-Emissions, the meaning of E-Mobility becomes more and more important. The related development of efficient Li-ions with high charge densities has also a direct impact on the automotive industry. This applies in particular to the crash safety of Li-ion-battery-powered vehicles. The structure of Li-ion batteries is in principle a repetitive layered system.

• Simplified modeling of self-piercing riveted joints for crash simulation with a modified version of *CONSTRAINED_INTERPOLATION_SPOTWELD

  Matthias Bier, Silke Sommer (Fraunhofer Institute for Mechanics of Materials IWM, Germany)

  The requirements for energy efficiency and lightweight construction in automotive engineering rise steadily. Therefore a maximum flexibility of the used materials is necessary and new joining techniques are constantly developed. The resulting large number of joints with different properties leads to the need to provide for each type of joint an appropriate modeling method for crash simulation. In this paper an approach for a simplified model of a self-piercing riveted joint for crash simulation will be discussed. The used simplified model is a modified version of the *CONSTRAINED_ INTERPOLATION_SPOTWELD. Firstly the realized modifications as a changed yield and failure behavior will be explained and illustrated. Therefore simulation results of the default and the modified version of the *CONSTRAINED_INTERPOLATION_SPOTWELD will be compared. Secondly the procedure to identify the appropriate model parameters will be presented and shown in an exemplary manner. At once the advantages and limitations of the model will be demonstrated. At least the quality of the model will be validated using simulations of different loaded T-joint experiments, which represents the connection between the rocker panel and the B-pillar. For this purpose three different characteristics will be taken into account: the global responses like the calculated and measured force vs. displacement curve of the punch, the local failure behavior and the order of failure of the rivet joints, and at last the internal forces in the simplified model.

• Simplified modeling of thin-walled tubes with octagonal cross section - axial crushing

  Yucheng Liu, Michael L. Day - University of Louisville

  This article investigates the collapse characteristics of thin-walled tubes with octagonal cross sections during axial crushing. The tubes’ axial crushing resistance (the relationship between crushing force and axial deformation) is described with a series of mathematical equations, which are derived applying global energy equilibrium theory. The derived axial crushing resistance is then used for developing simplified finite element models for the thin-walled octagonal tubes. The simplified finite element model is composed of beam elements and nonlinear springs, where the nonlinear springs were defined using the derived axial resistance and would be used to simulate the buckling behavior of the simplified model during crash analyses. The developed simplified models are used for crash analyses, and the results are compared to those from corresponding detailed models as well as from the published literatures. Relatively good agreement is achieved through these comparisons, and it shows that the simplified models can save much more computer resources and modeling labor compared to the detailed models. Explicit code LS-DYNA is used for all the modeling and simulation presented in this article.

• Simplifying the Pre-Simulation Set Up of Airbag Folding in LS-DYNA® Using ANSA

  Thanassis Fokylidis, Stavros Porikis (BETA CAE Systems S.A.)

  Crash and Safety simulations of virtual models hold a key role during the design process of a vehicle. Occupant protection analyses combined with laboratory tests ensure that models will offer the necessary safety to passengers. Airbags are one of the many protection systems that ensure this safety. During model set up for occupant safety simulations, significant time is consumed to fold the airbags properly and fit them in the respective cases. Airbag folding in virtual models follows the exact specifications given for the real airbags. LS-DYNA, as a standard solution in Crash and Safety analysis supports the folding of an airbag. The loadcase set up, for preparing the respective pre-crash simulation, may include the definition of several LS-DYNA keywords. BETA CAE Systems has developed an assistant functionality, in the ANSA pre-processor, which streamlines all the necessary steps to set up properly a LS-DYNA pre-simulation for airbag models. The current paper introduces this assistant and demonstrates the advantages of the procedure by ensuring a convenient LS-DYNA loadcase set up with the minimum effort.

• Simulating Dynamic Loads on Concrete Components using the MM-ALE (Eulerian) Solver

  S. K. Tay, R. Chan, J. K. Poon (Ministry of Home Affairs)

  A 3-stage loading on a reinforced concrete beam-column involving pre-load, blast and post-blast compression to failure was analyzed with the S-ALE solver. This paper presents the findings from the simulation and the results were compared to full-scale blast trials of reinforced concrete beam-column test specimens.

• Simulating Global Motion of the Brain in Response to Trauma

  Kyle Villalobos

  This research constructs a three-dimensional (3D) topological model that comprehensively predicts the macroscopic movement of the brain within the skull [5]. The consideration of impact angles and cerebrospinal fluid dynamics highlights the unique forces of various injurious scenarios [1][6]. To accomplish these tasks, the project utilizes ANSYS LS-DYNA's finite element capabilities, which captures the nuanced interactions of the aforementioned factors derived through a series of differential equations. This holistic approach provides unprecedented insights into the brain's dynamic response to forces.

• Simulating Pellet and Clad Mechanical Interactions of Nuclear Fuel Rod for Pressure Water Reactors

  W. Zhao, D. Mitchell, R. Oelrich (Westinghouse Electric Company LLC)

  Pellet-cladding mechanical interaction (PCMI) is a potential failure mode leading to leaking fuel rods. Ever-increasing fuel duty and more demanding power maneuvers for adapting to alternative energy sources create new challenges for maintaining the high standard of fuel rod structural integrity. Towards meeting the new challenges, the paper describes an on-going effort in developing a coupled thermal-structural model suitable for simulating the complicated PCMI phenomena under normal operations, operational transients, and accident conditions. The models and various application examples are presented in the paper, including off-centered pellet, missing pellet surface, and pellet cracking. The work utilizes the commercial finite element software LS-DYNA ® (LS-DYNA is a registered trademark by Livermore Software Technology Corporation, 7374 Las Positas Road, Livermore, CA 94550, www.lstc.com.)

• Simulating Prepreg Platelet Molding Compound Flexure Coupons in LS-DYNA® Using MAT54

  Rebecca A. Cutting, Anthony J. Favaloro, Johnathan E. Goodsell (Purdue University)

  Prepreg platelet molding compound (PPMC) is a composite material system primarily for compression molding comprised of rectangular platelets made from slit and chopped unidirectional prepreg. Prior to processing, the platelets are assumed to be in a planar random orientation state; however, this changes during molding as the platelet orientation state evolves in response to flow. The final orientations of the platelets affect the mechanical performance of manufactured components. As such, it is necessary to incorporate platelet orientations in simulations of PPMC parts to capture the material system behavior. This work introduces a modeling method for simplified PPMC geometries using MAT54 in LS-DYNA. A platelet generation code creates virtual PPMC samples with varying global orientation distributions. These orientations are input into LS-DYNA models of flexure coupons. A study is completed to understand how global platelet orientation affects the flexural stiffness and strength of the virtual samples. In addition, the results of the flexure simulations are compared to experimental results of flow-aligned PPMC coupons to validate the modeling method. The simulation study reveals that an increase in platelet alignment along the longitudinal axis of the sample results in an increase in flexural stiffness and strength in the models. This trend is confirmed experimentally, and the accuracy of the modeling method is discussed.

• Simulating Reinforced Concrete Beam-Column Against Close-In Detonation using S-ALE Solver

  Shih Kwang Tay, Roger Chan, Jiing Koon Poon (Minstry of Home Affairs

  A 3-stage loading on a reinforced concrete beam-column involving pre-load, blast and post-blast compression to failure was analyzed with the S-ALE solver. This paper presents the findings from the simulation and the results were compared to full-scale blast trials of reinforced concrete beam-column test specimens.

• Simulating Safe Landing : A Deep Dive into Parachute Inflation and Float with LS-DYNA

  Suraj Dhomase, Chandra Sekhar Kattmuri, Rodrigo Paz, Karthik Chittepu

  Parachutes for aerospace application is a new research area in the current era of space science. The scope of our project includes parachute design and inflation techniques. The current research project focuses on the following application areas: ● Parachutes for Re-entry Capsule ● RLV Parachutes Parachutes are used as aerodynamic decelerators in airdrop systems, so inflation is a significant fluid-structure interaction (FSI) phenomenon. New patterns of parachutes are constantly being developed and tested for airdrop systems but this research into parachute inflation is heavily reliant on historical experimental data. Till now, no parachute inflation model that is not based on this experimental data was developed. Material and instrumentation have changed significantly since the early experimental testing, yet the methods to develop the parachutes can still be traced to the same techniques used over ninety years ago. Rapid development of computational technology and modern computational mechanics combined with numerical simulation techniques have become more widespread in parachute research field and would enable us to develop the parachutes that are more optimized.

• Simulating Shot Peening: Application on leaf springs

  Christos Gakias, Georgios Savaidis

  Shot peening (SP) is a widely used process of surface treatment, based on the impact of small spheres (shots) on the surface of a component. The impact results on a localized plastic deformation and the development of a compressive residual stress field, that can extend up to a depth of 300-400 μm. This stress field significantly improves the fatigue life of components and prevents the initiation of small cracks. SP treatment can be influenced by various parameters, such as the velocity of shot peening media, many of them, governed by stochasticity.

• Simulating Structural Resistance of D&I Food Cans to Open Up Downgauging Potential

  B. Liebscher, F. Knieps, I. Weinand

  To reduce cost and increase the efficiency of D&I food cans, a lighter can with the same axial stability and paneling resistance is required. Axial stability depends on wall thickness, bead geometry (mainly bead depth) and tensile strength in the wall, whereas paneling resistance is a function of wall thickness, Young’s modulus and bead geometry (mainly bead depth), with the bead depth having an opposite influence on paneling resistance and axial stability. FEA is used to find a bead geometry that satisfies both the paneling resistance and axial stability requirements. For a stable calculation of the paneling resistance, perturbation in the form of an eigenmode is required. The calculation time is significantly reduced by using an implicit solver with arc length method. When simulating axial stability, accurate modeling of the beginning of the flow curve is required. A weight reduction of 5% can be achieved by using next-generation high-strength D&I steel grades (e.g. rasselstein® D&I Solid).

• Simulating the Complete Forming Sequence for a Roll Formed Automotive Bumper Beam

  Trevor Dutton, Paul Richardson - Dutton Simulation Ltd, Matt Tomlin, Tom Harrison - Wagon Automotive plc

  As part of the development of a new automotive bumper beam, a complete simulation of the entire forming process was carried out using LS-DYNA. The material for the beam was an ultra high strength steel presenting many challenges for the forming process. The sequence of forming operations was roll-forming (including forming a sweep in the initially straight roll-formed section), local annealing, forming of an initiator in the wall of the section and then crushing the end of the previously rolled section. The forming results (geometry, thinning and work hardening) were all transferred to the simulation of the bumper performance under various impact conditions. The paper describes the development of certain novel simulation techniques, particularly for the roll-forming for which the implicit analysis options of LS-DYNA were used, representation of the annealing process, as well as the method in which data was transferred between the various simulations. Above all, we describe how the simulations were used to guide the design of the bumper beam system up to the point of prototype manufacture and test.

• Simulating the hot press processing of structural thermoplastic foams

  S. Cassola, M. Duhovic, M. Salmins, P. Mitschang

  Thermoplastic foams allow the manufacture of lightweight parts with good thermal and acoustic insulation properties, particularly suited for aircraft interior and cabins structures. Such foams can be combined with skin layers of organic sheet materials (e.g. glass fiber (GF) polycarbonate (PC)) forming sandwich structures, enhancing the mechanical properties, but which unfortunately do not fulfil strict FST (Fire, Smoke and Toxicity) standards. An alternative approach uses the foam itself to create an integrated sandwich structure of an unmodified core and two skins of high density from the same material.

• Simulating the Impact Response of Composite Airframe Components

  Karen E. Jackson, Justin D. Littell (NASA Langley Research Center), Edwin L. Fasanella (National Institute of Aerospace)

  In 2010, NASA Langley Research Center obtained residual hardware from the US Army’s Survivable Affordable Repairable Airframe Program (SARAP), which consisted of a composite fuselage section that was representative of the center section of a Black Hawk helicopter. The section was fabricated by Sikorsky Aircraft Corporation and was subjected to a vertical drop test in 2008 to evaluate a tilting roof concept to limit the intrusion of overhead mass items, such as the rotor transmission, into the fuselage cabin. As a result of the 2008 test, damage to the hardware was limited primarily to the roof. Consequently, when the post-test article was obtained in 2010, the roof area was removed and the remaining structure was cut into six different types of test specimens including: (1) tension and compression coupons for material property characterization, (2) I-beam sections, (3) T-sections, (4) cruciform sections, (5) a large subfloor section, and (6) a forward framed fuselage section. In 2011, NASA and Sikorsky entered into a cooperative research agreement to study the impact responses of composite airframe structures and to evaluate the capabilities of the explicit transient dynamic finite element code, LS-DYNA®, to simulate these responses including damage initiation and progressive failure. Finite element models of the composite specimens were developed and impact simulations were performed. The properties of the composite material were represented using both a progressive in-plane damage model (Mat 54) and a continuum damage mechanics model (Mat 58) in LS-DYNA. This paper provides test-analysis comparisons of time history responses and the location and type of damage for representative I-beam, T-section, and cruciform section components.

• Simulating the Impact Response of Full-Scale Composite Airframe Structures

  Edwin L. Fasanella (National Institute of Aerospace), Karen E. Jackson, Justin D. Littell (NASA Langley Research Center), Michael D. Seal (Analytical Mechanics Associates, Inc.)

  NASA Langley Research Center obtained a composite helicopter cabin structure in 2010 from the US Army’s Survivable Affordable Repairable Airframe Program (SARAP) that was fabricated by Sikorsky Aircraft Corporation. The cabin had been subjected to a vertical drop test in 2008 to evaluate a tilting roof concept to limit the intrusion of overhead masses into the fuselage cabin. Damage to the cabin test article was limited primarily to the roof. Consequently, the roof area was removed and the remaining structure was cut into test specimens including a large subfloor section and a forward framed fuselage section. In 2011, NASA and Sikorsky entered into a cooperative research agreement to study the impact responses of composite airframe structures and to evaluate the capabilities of the explicit transient dynamic finite element code, LS-DYNA®, to simulate these responses including damage initiation and progressive failure. Most of the test articles were manufactured of graphite unidirectional tape composite with a thermoplastic resin system. However, the framed fuselage section was constructed primarily of a plain weave graphite fabric material with a thermoset resin system. Test data were collected from accelerometers and full-field photogrammetry. The focus of this paper will be to document impact testing and simulation results for the longitudinal impact of the subfloor section and the vertical drop test of the forward framed fuselage section.

• Simulating the Induction Heating Behavior of CFRTPC Laminates

  M. Duhovic, T. Hoffmann, S. Becker, P. Mitschang (TU Kaiserslautern)

  The objective of this work is to create an FEM-based model for the inductive heating of carbon fiber reinforced thermoplastic composite (CFRTPC) laminates. A macroscale simulation model was created using the multi-physics capabilities of LS-DYNA®. Material model parameters were largely determined by micromechanical considerations. In order to further increase the accuracy of the FEM model, dynamic differential calorimetry (DSC) measurements were also carried out to determine the temperature dependence of the heat capacity of the laminates investigated. The model was then validated for laminates reinforced by non-crimped fabrics (NCF) with fiber volume contents (FVC) of 32%, 47% and 60% via induction heating tests. In general, the heating experiments could be approximated well both qualitatively and quantitatively. Furthermore, analyses were carried out in order to investigate the influence of individual ply orientations in the laminate on one another as well as the influence of the layer thickness on the resulting heating behavior.

• Simulating the Induction Spot Welding of Hybrid Material Joints

  M. Didi, D. Wind, M. Duhovic, J. Hausmann (Technical University Kaiserslautern)

  Spot welding is a very common process used to join sheet metal components in the automotive industry mass production environment. Recently, thermoplastic composites as light weight alternatives to metals have begun to make their way into production. The induction spot welding of hybrid materials, in particular aluminum or steel to thermoplastic based composite materials, is one promising method to create the required connections between these dissimilar materials and maintain productivity. As opposed to continuous welding, the spot welding of two materials with different thermal properties can help prevent heat distortion and internal stresses in parts.

• Simulating the Joining of Composite Materials by Electromagnetic Induction

  M. Duhovic, L. Moser, P. Mitschang, M. Maier (Institut für Verbundwerkstoffe GmbH), I. Caldichoury, P. L'Eplattenier (LSTC)

  The development of the electromagnetism module in LS-DYNA (980 solver) was in the past primarily driven by the need for Electromagnetic Metal Forming (EMF) simulation capabilities. As the module matures, new applications in particular in the field of induction heating for thermoplastic composite welding/joining have appeared, providing a crucial simulation tool for composite manufacturing processes utilizing this technology. In this work, induction heating characterization tests involving static plate specimens using different induction heating processing parameters have been performed and then simulated. Finite element models have been built in both LS-DYNA and COMSOL and the results and capabilities of both software codes are discussed and compared.

• Simulating the Motion of Heart Valves Under Fluid Flows Induced by Cardiac Contraction

  Eann A. Patterson, Chris J. Carmody, Ian C. Howard - The University of Sheffield

  The motions of natural and replacement valve leaflets are complex functions of a large number of interactions. The principle concern of the simulation work is the investigation of how natural valves operate whilst attached to a deformable aorta close to its connection with the left ventricle. This involves the interaction of a fluid flow with soft, highly deformable structures. LS-DYNA was used to analyse the system using a series of models with fluid- solid interaction. A ventricle model helped create a detailed prediction of the temporal and spatial variation of flow into the aorta as the ventricle contracts. The principle input to this model was experimental data on displacements. This allowed a flow pattern to emerge naturally in the ventricle. This flow pattern was then available for input into the aortic valve model. The creation of this was a significantly non-trivial task. There are several aspects whose computational demands can be mutually destructive without care in the modelling. These include the effects of contact, spatially moving flow gradients, and the large deformations of the aortic wall and the sinuses. The development of the aortic valve model used linear elastic properties for the different solid materials. Subsequently the simulation progressed to using fully non-linear properties. The paper highlights some of the difficulties encountered and the solutions found, as well presenting some of the results.

• Simulation and Analysis of the Beverage Can Necking Process Using LS-DYNA

  A. Jordan-Cordera, J.C. Miranda-Valenzuela - ITESM Campus Toluca

  Due to their large production quantities, beverage cans have been the subject of many studies. Such studies have as objectives to increase the level of understanding of the structural behavior of the can as well as its manufacturing process. In this work, the necking process is studied by means of a parameter response study carried out with the help of LS-DYNA. Even when the necking process is affected by many factors including can geometry, material properties, tool geometry, friction coefficient between the tools and the can, punch speed, etc., in this study only four variables are taken into account: friction coefficient, punch speed, can thickness and can radius.

• Simulation and Test Validation of Windscreen Subject to Pedestrian Head Impact

  Q. Liu, J. Liu, Q. Miao, D. Wang, X. Tang (SAIC Motor Technical Center)

  Pedestrian head impact with windscreen is one of the major causes for pedestrian severe injury or fatality. A FE model is established with shell and solid elements representing different layers of a laminated windscreen. Major strain criterion is used to deal with the failure of windscreen. Simulation results are validated by Euro NCAP pedestrian head-to-windscreen impact tests. The results show that the FE modeling of windscreen can effectively predict the pedestrian head injury and the failure pattern of the windscreen. This method can be an effective tool for vehicle pedestrian safety evaluation and development.

• Simulation and Testing Assessment of Cruciform Parachutes using LS-DYNA® ALE

  Terence Rose, Gregory Noetscher, Keith Bergeron,, U.S. Army Natick Soldier Research, Development & Engineering Center

  This work presents a model of the coupled aero- and structural dynamics for a cruciform parachute which can then be used to inform development of control schemes for autonomously guided airdrop systems. Currently, the United States Army uses a combination of ram-air parachutes, as part of the Joint Precision Airdrop System (JPADS), and ballistic unguided parachutes to deliver supplies in austere locations. Ram-air parachutes are highly maneuverable systems and when paired with Guidance, Navigation and Control (GN&C) flight software can be highly accurate. While a cruciform or cross parachute is significantly less maneuverable, it may offer a more cost effective alternative to deliver cargo and assist disaster relief efforts. By extending and retracting various suspension lines, which connect the payload to the parachute, different forces and moments can be manipulated for steering control. A two-way fluid-structure interaction (FSI) model was created using the LS-DYNA Arbitrary Lagrangian-Eulerian (ALE) solver. Quantitative and qualitative experimental and flight test data are used to validate the baseline model. Subsequent simulations investigate different control schemes and geometry changes to enable rapid testing and inform/guide future experiments and drop tests.

• Simulation and Validation of FMVSS 207/210 Using LS-DYNA

  Vikas Patwardhan, Tuhin Halder, Frank Xu, Babushankar Sambamoorthy - Lear Corporation

  Federal Motor Vehicle Safety Standard 207 and 210 applies to automotive seats, their attachment assemblies, and seat belt anchorage assemblies. These regulations ensure their proper location for effective occupant restraint, and it also minimizes the possibility of anchorage failure due to the forces resulting from a vehicle crash. These requirements are the most critical in seat development process and are generally considered the benchmark for an automotive seat’s safety performance. Finite Element Analysis (FEA) is widely used to simulate the FMVSS 207/210 on a component level as well as on a complete seat system level. Quasi-static simulation using LSDYNA is one of the chosen methods to simulate the requirement. This paper will discuss a simple but accurate method to simulate and validate the FMVSS 207/210 test. The methodology describes the use of lighter body blocks to reduce the dynamic effect, simpler seat belt formulations, and the right use of element formulations and contact interfaces.

• Simulation and Validation of UNDEX Phenomena Relating to Axisymmetric Structures

  R. Boyd - Altair Engineering Ltd, R. Royles - University of Edinburgh, K. M. M. El-Deeb - Linear & Non-linear Structural Dynamics Ltd

  Numerical modelling of underwater explosion (UNDEX) loading using LS-DYNA was studied in free field conditions and in relation to an axisymmetric thin shell of revolution - an echinodome in a floating submerged and tethered configuration. The formulation utilised was multi-material arbitrary Lagrangian Eulerian. Based on preliminary modelling, backed by existing data, numerically reproducible experiments were designed for validation purposes. The mesh generation and experimental validation are described and compared.

• Simulation and Verification of the Drop Test of 3C Products

  Hsing-Ling Wang - Chinese Air Force Academy, Shia-Chung Chen, Lei-Ti Huang, Ying Chieh Wang - Chung-Yuan Christian University

  Drop test performance has become one of the most crucial evaluations for Computer, Communication, and Consumer (3C) products. Both simulation tool and practical platform for drop test must be established for detailed study. A patented drop test platform is designed for the purpose of impact angle repeatability and instantaneous drop image capture at impact instance. These parameters are two crucial computer-aid-engineering (CAE) inputs used for drop impact simulations. Post data processing procedures such as sampling rate, and signal filtering specifications was also studied and found to be important for the accurate interpretation of drop simulations as well. It was found from simulations that a small angle variation ( 5°) may result in up to 36% difference in predicted ± internal stress. Accurate identification on the impact angle, therefore, is recommended as an important parameter on internal component stress calculation. Good consistency between measured acceleration data and simulated results verifies the practicality of the developed data processing procedure and numerical methodology.

• Simulation Aspects for the Application of High Strength Steel Materials in Forming Processes

  L. Keßler, T. Beier, H. Richter (ThyssenKrupp Steel Europe)

  High-strength, cold-formable steels offer great potential for meeting cost and safety requirements in the auto industry. In view of strengths of up to 1200 MPa now attainable, some aspects need to be analyzed and evaluated in advance when designing with these materials. In addition to early assessment of crash properties, it is also highly important to design the forming process to match the material potential. To address the material potential by simulation a complete row of different tasks has to be fullfilled

• Simulation Data Management from CAD to Results with LoCo and CAViT for Large Scale LS-DYNA® LEGO® Crash Models

  Thorsten Gerlinger, David Koch, Andre Haufe (DYNAmore GmbH), Nils Karajan, Thomas Weckesser (DYNAmore Corporation), Pierre Glay (DYNAmore France SAS), Alexandru Saharnean, Marko Thiele (SCALE GmbH)

  Given that in our professional lives we are dealing with highly sophisticated crash models on a daily basis, it seems obvious that we instantly thought we should be able to simulate a crash of a LEGO® Porsche Technic Model using the LS-DYNA FEM solver after seeing a video of a physical crash of this model on YouTube. Setting up a process, which involves every aspect of working with CAD data, meshing, dealing with solver files, submitting and monitoring the simulations, and finally handling the result files of simulations, is an important step when developing a Simulation Data Management (SDM) system such as LoCo and CAViT. Therefore we decided to use this LEGO® crash as a challenge and benchmark for our software. The real LEGO® models are often assembled with thousands of bricks. Handling so many parts in a SDM system on one hand and maintaining the ability to work on such models in a collaborative way with multiple users on the other is quite challenging. Initially, we set up the whole simulation process for the Porsche which is composed of 2704 individual bricks. But when we showed the results of the LEGO® Porsche crash simulation to the c’t magazine (a widely read German computer magazine) and ADAC (General German Automobile Club) who had performed the initial physical crash test in 2017, they suggested doing another LEGO® crash scenario. This time a LEGO® Porsche was supposed to crash into a LEGO® Bugatti model at 60km/h and a LS-DYNA simulation should predict the outcome of the crash before the physical test was going to be conducted. The LEGO® set number 42083 of the Bugatti Chiron is even bigger than the Porsche model and consists of 3599 bricks. The results of the simulation were then evaluated and presented to ADAC and c’t magazine to provide our prediction of the upcoming real physical crash. Later, the comparison of our prediction with the real crash results revealed that many details have been predicted correctly by the simulation. The final LS-DYNA model of both car models consisted of more than 45 million elements. Preprocessing as well as getting the model to run on an HPC system and handling the few but large result files has proven to be challenging in many ways.

• Simulation for Forming and Performance Evaluation of Structures Developed Based on the Concept of "ORIGAMI Engineering"

  Sunao Tokura (Tokura Simulation Research Corp.)

  The “origami” is known as one of traditional Japanese craftwork. Origami is a technique of paper folding in which various complex shapes of birds, flowers and so on can be made from a simple sheet of paper. Origami is also considered as a technique to produce light weight three dimensional structures from two dimensional material. And the 3D structures of origami can be foldable and/or expandable. Recently origami engineering inspired by traditional origami has been advocated by some researchers. Although several excellent structures have been studied ideally and mathematically so far, from a viewpoint of engineering, formability of the origami structure is a very important engineering issue practically even if the structure has excessively elegant shape. There are two major origami structures, i.e., the “octet-truss core panel (shortly truss core panel)” and the “reversed spiral origami tube”. In this paper the formability, strength and crash performance of these origami structures are discussed. The explicit FE code LS- DYNA® is the main solver of these problems. The press forming simulation software JSTAMP is used for formability assessment and the optimization software LS-OPT® is used to study crash performance.

• Simulation of a clamping ring under high dynamic loading

  S. Edelmann, C. Groß, H. Chladek - INPROSIM GmbH

  Clamping rings are used in a wide range of mechanical applications in order to assemble two or more cylindrical parts, e.g. tubes and pipes, pressure vessels and tanks. Another application area of clamping rings is in turbo engines, where they connect compressor, bearing and turbine casings for example. For normal operating conditions, standard rules or simple static analyses are adequate to determine the relevant design parameters of this device. But these analyses are not sufficient for highly dynamic loading as in case of misuse or failure, e.g. shock waves, compressor surge and in particular the impeller burst. In these cases the loading of the clamping ring is no longer static nor linear. The impulse transmitted and the mass inertia of the parts connected play an essential role for the loading scenario. In addition the non-linear material behaviour, the high geometric deformation and plastification up to material failure as well as the complex contact situation have to be taken into account. For these extensive analyses explicit simulations using LS-DYNA have proven to be a highly efficient tool. This presentation gives an overview on how to use CAE simulation for designing a clamping ring for highly dynamic loading. As a first step in the process described, a quasi-static pullout test is used to achieve a high correlation between hardware testing and simulation. The paper also gives an idea of the influences of some typical design parameters of a clamping ring, e.g. wall thickness and numbers of segments of the v-shaped lower strap. A focus of the development needs to be on the balance of structural stiffness of the clamping ring for one thing and the flanges of the parts connected for another. The presentation concludes by showing a successful simulation using LS-DYNA Explicit for the highly loaded clamping ring due to an impeller burst.

• Simulation of a clamping ring under high dynamic loading

  S. Edelmann, C. Groß, H. Chladek - INPROSIM GmbH

  Clamping rings are used in a wide range of mechanical applications in order to assemble two or more cylindrical parts, e.g. tubes and pipes, pressure vessels and tanks. Another application area of clamping rings is in turbo engines, where they connect compressor, bearing and turbine casings for example. For normal operating conditions, standard rules or simple static analyses are adequate to determine the relevant design parameters of this device. But these analyses are not sufficient for highly dynamic loading as in case of misuse or failure, e.g. shock waves, compressor surge and in particular the impeller burst. In these cases the loading of the clamping ring is no longer static nor linear. The impulse transmitted and the mass inertia of the parts connected play an essential role for the loading scenario. In addition the non-linear material behaviour, the high geometric deformation and plastification up to material failure as well as the complex contact situation have to be taken into account. For these extensive analyses explicit simulations using LS-DYNA have proven to be a highly efficient tool. This presentation gives an overview on how to use CAE simulation for designing a clamping ring for highly dynamic loading. As a first step in the process described, a quasi-static pullout test is used to achieve a high correlation between hardware testing and simulation. The paper also gives an idea of the influences of some typical design parameters of a clamping ring, e.g. wall thickness and numbers of segments of the v-shaped lower strap. A focus of the development needs to be on the balance of structural stiffness of the clamping ring for one thing and the flanges of the parts connected for another. The presentation concludes by showing a successful simulation using LS-DYNA Explicit for the highly loaded clamping ring due to an impeller burst.

• Simulation of a CMVSS 215 bumper pendulum test series with LS-DYNA

  Armin Huß, Heiko Beck, Ingenieurbüro Huß & Feickert, Germany

  In the course of an increasing automotive development for international markets many new loadcases have to be tested. The Canadian bumper pendulum test (CMVSS215) is one of these loadcases that form a special challenge for the simulation with LS-DYNA due to its sequential process. For this test four different bumper pendulums have to impact the vehicle, while with each new test the prior damages have to be taken over. Until now the simulation had to be interrupted after each impact due to the necessity of repositioning the vehicle to the initial state. This demands personal intervention of an engineer after each of the first three impacts costing useful time. In some cases complex scripts are run between the impacts to reposition the car, which has the advantage of being independent of human intervention, but still these are time-consuming methods. Much more practicable and feasible is a solution directly using the possibilities of LSDYNA which neither cost any script processing time nor affords human intervention. At Ingenieurbüro Huß & Feickert a method was developed which links the motion of the impactors to the movement of the car so that each pendulum can start in the right initial position for the specific loadcase. Thus the test can be performed in one single run saving useful time for development.

• SIMULATION OF A DETONATION CHAMBER TEST CASE

  Daniel Hilding - Engineering Research Nordic AB

  The purpose of a detonation chamber is to ensure vapor and fragment containment during the destruction of explosive munitions. The toxic vapors generated by the detonation can be vented into a filtration unit. Compared to free air detonations, the use of a detonation chamber reduces the environmental impact of munitions destruction. The manufacture and testing of a detonation chambers is time consuming and expensive. At present, new designs are mainly based on experience with previous designs and rough estimates. A more accurate and reliable method for predicting a chambers performance would therefore be a significant aid in the design process. This paper considers the most straightforward method for predicting the performance of a chamber design, which is to simulate a munitions detonation in the chamber. The simulation is accomplished using LS- DYNA's multi-material Eulerian methods.

• Simulation of a Mine Blast Effect on the Occupants of an APC

  A. Brill, B. Cohen - RAFAEL Ballistic Center, Israel, P. Du Bois, Consulting Engineer, Germany

  In this paper the use of LS-DYNA for the simulation of a mine blast load on an armoured personnel vehicle is presented with comparison to a full test. The investigated vehicle is an M113 APC with occupants seated in commercial seats. Different approaches to the numerical analysis of this complicated event are presented and results are compared. In particular the blast load is applied using the standard engineering model (CONWEP) because of the obvious computational advantages of this approach. However, a fully coupled finite element analysis simulating the interaction between the blast wave, the detonation gases and the vehicle was also performed. It is shown that the classical engineering model can severely underestimate the load on the APC. The use of the LS-DYNA component dummy models for the simulation of the occupants is also illustrated. The numerical simulations using LS-DYNA hydrocode were in good agreement with the experimental results. Those results show that the normal accelerations measured in the dummies pelvis are lower than the critical acceleration.

• Simulation of a Railgun: A Contribution to the Validation of the Electromagnetism Module in LS-DYNA v980

  I. Caldichoury, P. L'Eplattenier (LSTC)

  A railgun is an electrical gun using electromagnetic forces in order to accelerate and launch projectiles at several times the speed of sound. Railguns have long belonged to the science-fiction world or existed as experimental and demonstrator technology. However in recent years, the U.S Navy has shown an increased interest for Railguns as they offer the potential for reduced logistics and firing power. The purpose of this paper is to simulate a railgun model using the Electromagnetism solver in LS-DYNA, to compare results with existing analytical models and to show how LS-DYNA may help to improve such existing models.

• Simulation of a Thin Walled Aluminum Tube Subjected to Base Acceleration Using LS-DYNA's Vibro-Acoustic Solver

  Ofir Shor, Yoav Lev -Rafael, Yun Huang - LSTC

  A shaker table test, where a simple thin walled aluminum tube was base accelerated at two geometrical locations, was simulated using the vibro-acoustic solver of LS-DYNA. It was shown that the method of modeling the fixture of the tube to the shaker table's moving plate had a great impact on the simulation result. Three modeling methods of the fixture were tested, and acceleration PSD results at various points along the tube were compared to test data. A simple, numerically low-cost method, of modeling the fixture was found which gave very good agreements with the experimental data.

• Simulation of a Vehicle Running on to a Curb by Using Tire and Vehicle FE Models

  Tatsuya Fukushima,, Hitoshi Shimonishi - NISSAN MOTOR CO.,LTD, Kimihiro Hayashi - The Japan Research Institute, Limited, Masaki Shiraishi - SUMITOMO RUBBER INDUSTRIES, LTD

  A simplified FE tire model has capability to solve a large deformation of a tire on a vehicle running simulation with acceptable computational time. We tried to simulate a vehicle running on to a curb, one of vehicle strength tests, by using simplified FE tire models and a vehicle FE model which has detailed suspension models. It is necessary to solve the force to a wheel with good agreement with a car test, in order to estimate the force to suspension systems or a body as a vehicle strength problem. We confirmed that the simulated force to a wheel agreed with the force by car test.

• Simulation of acoustic and vibroacoustic problems in LS-DYNA using boundary element method

  Yun Hang - Livermore Software Technology Corporation, Mhamed Souli - University of Lille Laboratoire Mecanque de Lille, Rogelio Perez - Schneider Electric Industries Calcul & Simulation

  The present work concerns the new capability of LS-DYNA® in solving acoustic and vibroacoustic problems. In vibroacoustic problems, which are assumed to be weak acoustic-structure interactions, the transient structural response is computed first. By applying the FFT, it is transformed into a frequency response. The obtained result is taken as boundary condition for the acoustic part of the vibroacoustic problem. Consequently, the radiated noise at any point into space can be calculated. The new developed LS-DYNA keyword is based on boundary element method (BEM) in which only the surface of the acoustic domain needs to be discretized. Besides BEM that solves the Helmholtz equation as a linear system, the new card allows, also, to use two other approximative Rayleigh and Kirchhoff methods. Both methods do not require a system of equations to be assembled and solved. Consequently, they are faster than BEM. Rayleigh method assumes that the radiating structure is a plane surface clamped into an infinite rigid plane. In Kirchhoff method, BEM is coupled to FEM used for acoustics in LS-DYNA by prescribing non reflecting boundary condition. In this case, at least one fluid layer needs to be merged to the vibrating structure.

• Simulation of acoustic and vibroacoustic problems in LS-DYNA using boundary element method

  Ahlem Alia, Mhamed Souli - LSTC, James Hargreaves, Brian Walker - ARUP, Mojtaba Moatamedi - University of Salford

  The present work concerns the new capability of LS-DYNA® in solving acoustic and vibroacoustic problems. In vibroacoustic problems, which are assumed to be weak acoustic-structure interactions, the transient structural response is computed first. By applying the FFT, it is transformed into a frequency response. The obtained result is taken as boundary condition for the acoustic part of the vibroacoustic problem. Consequently, the radiated noise at any point into space can be calculated. The new developed LS-DYNA keyword is based on boundary element method (BEM) in which only the surface of the acoustic domain needs to be discretized. Besides BEM that solves the Helmholtz equation as a linear system, the new card allows, also, to use two other approximative Rayleigh and Kirchhoff methods. Both methods do not require a system of equations to be assembled and solved. Consequently, they are faster than BEM. Rayleigh method assumes that the radiating structure is a plane surface clamped into an infinite rigid plane. In Kirchhoff method, BEM is coupled to FEM used for acoustics in LS-DYNA by prescribing non reflecting boundary condition. In this case, at least one fluid layer needs to be merged to the vibrating structure.

• Simulation of acoustic and vibroacoustic problems in LS-DYNA using boundary element method

  Yun Hang - Livermore Software Technology Corporation, Mhamed Souli - University of Lille Laboratoire Mecanque de Lille, Rogelio Perez - Schneider Electric Industries Calcul & Simulation

  The present work concerns the new capability of LS-DYNA® in solving acoustic and vibroacoustic problems. In vibroacoustic problems, which are assumed to be weak acoustic-structure interactions, the transient structural response is computed first. By applying the FFT, it is transformed into a frequency response. The obtained result is taken as boundary condition for the acoustic part of the vibroacoustic problem. Consequently, the radiated noise at any point into space can be calculated. The new developed LS-DYNA keyword is based on boundary element method (BEM) in which only the surface of the acoustic domain needs to be discretized. Besides BEM that solves the Helmholtz equation as a linear system, the new card allows, also, to use two other approximative Rayleigh and Kirchhoff methods. Both methods do not require a system of equations to be assembled and solved. Consequently, they are faster than BEM. Rayleigh method assumes that the radiating structure is a plane surface clamped into an infinite rigid plane. In Kirchhoff method, BEM is coupled to FEM used for acoustics in LS-DYNA by prescribing non reflecting boundary condition. In this case, at least one fluid layer needs to be merged to the vibrating structure.

• Simulation of Acoustic and Vibro-Acoustic Problems in LS-DYNA® using Boundary Element Method

  Yun Huang - Livermore Software Technology Corporation, Mhamed Souli - University of Lille, France

  The present work concerns the new capability of LS-DYNA® in solving acoustic and vibro-acoustic problems. In vibro-acoustic problems, which are assumed to be weak acoustic-structure interactions, the transient structural response is computed first. By applying the FFT, it is transformed into a frequency response. The obtained result is taken as boundary condition for the acoustic part of the vibro-acoustic problem. Consequently, the radiated noise at any point into space can be calculated. The new developed LS-DYNA keyword is based on boundary element method (BEM) in which only the surface of the acoustic domain needs to be discretized. Besides BEM that solves the Helmholtz equation as a linear system, the new card allows, also, to use two other approximative Rayleigh and Kirchhoff methods. Both methods do not require a system of equations to be assembled and solved. Consequently, they are faster than BEM. Rayleigh method assumes that the radiating structure is a plane surface clamped into an infinite rigid plane. In Kirchhoff method, BEM is coupled to FEM used for acoustics in LS-DYNA by prescribing non reflecting boundary condition. In this case, at least one fluid layer needs to be merged to the vibrating structure. Keywords: Acoustic, Vibro-acoustic coupling, FFT, Boundary element method

• Simulation of Agricultural Soil Tillage Machine using DEM

  H. Mouradjalian, Z.Asaf, I. Shmulevich (Technion - Israel Institute of Technology); B. Zion (Israeli Agricultural Research Organization)

  Increasing number of hit and run pedestrian accidents highlight the importance of accident reconstruction tools used in forensic investigations. The tools used nowadays are based on simplified assumption of particle – particle interactions (Searle’s model), or real life accidents (Happer’s model) which enable for prediction of the collision velocity based on pedestrian throw distance evidence obtained at the scene of the accident. Unfortunately, vehicle impact speeds can only be estimated as a range of velocities, as the Searle’s model forms a velocity corridor which widens with the increase of measured throw distance giving not accurate predictions. Development of computing architecture together with the advancement in computer human modelling opens the opportunity for bringing accident reconstruction studies to the next level and reducing the predicted velocities range. Nevertheless, to achieve this, the computer human models need to be reliable and robust. In this study, the Total Human Model for Safety (THUMS) was validated against analytical pedestrian throw distance models. The validation studies were performed with THUMS 4.0 at three different model stances and four different impact velocities (20, 30, 40 and 50 km/h) as well as three different stances, namely: standing, walking and running pedestrian. Analyses results were validated against Simulation of agricultural soil tillage machine is important for power consumption reduction during tillage processes. Potato and onion harvesting machines as well as other soil tillage machines need to penetrate into the ground and convey large amount of soil or root crops over a tilted pickup chain conveyor. These types of machines sustain extremely large loads that require heavy pulling tractors. The Israeli Agricultural Research Organization – Volcani Center developed such a machine for weed (Nutsedge) pest control. In this machine as in many others a large blade is placed in front of the conveyor which penetrates into the soil, tills the soil at a required operation depth and directs the tilled soil onto the conveyor. The mechanical design of the tillage blade and its position relative to the pickup conveyor has a great impact on the power efficiency of the machine. A small change in the operating angle of the blade or its position relative to the pickup conveyor can have a significant impact on the operation of the machine and on the acting drag forces that in turn might cause a significant waste of energy. The aim of this work is to simulate the machine-soil interaction as a tool for better machine design and to reduce the power requirements of the machine by the developed tool. The reported work used LS-DYNA dynamic analysis for modeling the machine by Lagrangian elements and the soil by cohesive Discrete Element (DE) particles to represent clay soil. Optimization of the blade’s shape, the position of the conveyor and their combination by trial and error experiments would be a long and expensive process. The parametric examination using the developed model showed significant difference in the drag forces between different blade designs and different blade orientations. The simulation was calibrated and validated by full scale experiments using the soil tillage machine puled by a tractor at an agricultural field. During the experiments two types of blades were compared at different tillage depths. The soil stiffness in field was measured by a dynamic cone penetrometer. Several other parameters were measured during the test: the drag forces and their direction, the tillage velocity and the depth of tillage. The experimental work validates the simulation. The results of the research show that over 25% power reduction can be obtained by optimal design of the blade shape, angle and position relative to the pickup conveyor using LS-DYNA DE model simulation.

• SIMULATION OF AIRBAG DEPLOYMENT USING A COUPLED FLUID-STRUCTURE APPROACH

  Per-Olof Marklund - Linköping University, Larsgunnar Nilsson - Engineering Research Nordic AB and Linköping University,

  This paper explores simulation techniques for airbag inflation using a coupled fluid-structure approach. The application is to be seen as an initial study on the phenomena occurring in an airbag during an Out of Position occupant impact. The application problem is an airbag that is set to impact a head form. The head form is positioned at a very short distance from the airbag. A Multi Material Arbitrary Lagrangian Eulerian technique in LS-DYNA is used for the fluid and it is coupled to the fabric structure using a penalty based fluid structure contact algorithm. The results of the head form acceleration and velocity show good agreement to the corresponding experimental results. The results also show that at the early stages of the inflation a high-pressure zone is built up between the inflow and the head form. The consequence of this is that the pressure difference between the inflow and the high pressure zone is too low for an a priori assumption of sonic flow at the inlet.

• Simulation of back-injection molded parts using MAT_058 and MAT_215

  Kai-Chien Chuang, Sanjay Kumar Sardiwal, Boris Cordero Porras, Patrick Scholz, Olaf Hartmann

  Within the modern automotive industry, long-fiber-reinforced polymers (LFRPs) have gained increasing popularity because of efficient production of complex geometries in combination with relatively high stiffness and strength. Increased mechanical performance can be achieved by combining LFRP with continuous fiber composites, such as UD-Tape while using back-injection molding. The combination of these two material types poses a challenge in CAE, because of their individual anisotropic behavior.

• Simulation of Ball Impact on Composite Plate with PP+30% LGF

  T. Sakakibara, R. Akita, Y. Ohnishi (ITOCHU Techno-Solutions Corp.), S. Kijima, Y. Kanki (UES Software Asia Inc.), M. Seto (Kanazawa Institute of Technology), K. Suda, K. Yamakawa, Y. Ayano (Toray Eng. Co.)

  The failure prediction of the long glass-fiber (LGF) reinforced resin is difficult because of the complicated fiber orientation compare to the short fiber. In order to establish a simulation procedure to represent the failure behavior of the LGF reinforced resin, we have carried out simulations of ball impact on the composite plate with ®polypropylene and 30% LGF using LS-DYNA coupled to DIGIMAT. The fiber orientation was calculated by the mold flow code 3D TIMON and the composite material properties and failure criterion were estimated and verified by DIGIMAT based on mean-field homogenization. The stiffness reduction and fracture progress in the simulation are represented by the First Pseudo Grain Failure model (FPGF). The numerical results of the impact simulation are discussed through comparing the experimental results.

• Simulation of Ballistic Impact on Composite Panels

  Matti Loikkanen - Propulsion Engineering Technology & Research, Grama Praveen - Global Research Center, General Electric Company, David Powell - University of California, Berkeley

  Ballistic impact on composite panels is studied in this work both experimentally and computationally. The purpose was to develop computational methods to analyze a high speed jet engine fragment impacting on composite targets. 12 inch by 12 inch laminated panels with 8, 16, and 32 plies and the standard +-45, 0 /90 degree stacking sequences were considered. With the nominal ply thickness of 0.0075 inches, the corresponding panel thicknesses were 0.06, 0.125 and 0.25 inches. The panels were mounted on a heavy steel frame and spherical and cylindrical projectiles were shot against composite plates. Several shots with varying impact speeds were fired against each panel thickness. The impact damage was observed, and the initial and exit speeds were measured. The ballistic tests indicated that the amount of energy absorbed during impact by a target is nearly constant showing only a slight increase with increasing initial energy. The amount of energy absorbed per ply increases only slightly for the thicker samples. In addition, the tests showed that the cylindrical projectiles required a larger amount of energy to penetrate the composite panels than did the spherical projectiles LS-DYNA® was used to simulate the tests. The panels were modeled with 8-node solid elements. *MAT_COMPOSITE_DMG_MSC (162) was used to model the orthotropic ply material. This model can be used to model progressive failure of composites with unidirectional and woven fabric fibers. One layer of solid elements was used through the thickness of each ply and several mesh densities were studied. A new Cohesive Contact formulation *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE_TIEBREAK (and ONE WAY TIEBREAK) made available as a “DYCOSS” option was defined between each ply to model delaminations. The cohesive contact - DYCOSS option 9 has been developed during this work. This delamination modeling feature is based on fracture mechanics and requires fracture toughness inputs for the composite material. Option 9 has both the power law and BK-law to account for Mode I and Mode II interaction and allows for a better definition of the constitutive laws. The main advantages of cohesive contact are that it allows the user to toggle very easily between ordinary tie-break based delamination models and cohesive contact models and there is no need for separate cohesive elements in the model. Good overall agreement was found between computations and testing.

• Simulation of Bird Strike on Airplane Wings by Using SPH Methodology

  M. Guler (TOBB University of Economics and Technology), T. Kiper Elibol (Turkish Aerospace), I. Uslan (Gazi University), M. Buyuk (Turkish Standards Institution)

  According to the FAA report, 142603 bird strikes were reported for a period of 24 years, between 1990 – 2013. Bird strike with aerospace structures not only threaten the flight security but also cause financial loss and puts life in danger. The statistics show that most of the bird strikes are happening with the nose and the leading edge of the wings. Also, a substantial amount of bird strikes are absorbed by the jet engines and causes damage on blades and engine body.

• Simulation of Blast Load Reduction on Walls with Foamed Concrete Boards

  Yijian Shi, PhD (ZASA - Logan, Zodiac Aerospace)

  A foamed concrete board (FCB), often used as an insulation layer in structures, has been used to study blast attenuation. A LS-DYNA ® explicit solver chosen as a simulation tool reveals the physics of pressure waves, which transfer through materials, and internal stress in detail. The effectiveness of blast attenuation is measured by the reduction of peak pressure acting on a rigid wall (RW) that is immediately behind the FCB. According to the simulation results, the internal stress in FCB can reach much higher than its static strength under the blast loading. The internal stress is a function of not only material's failure stress and strain/deformation, but also its density, elastic modulus, plastic properties, internal speed, and acceleration. This observation might result in the difficulty to measure the internal stress or load, because load cells and strain gages traditionally only measure the strain or deformation, which can be converted to stress statically. The simulation results indicate that the higher the pressure of the blast than the strength of FCB, the higher the reduction for the peak pressure on RW is. On the contrary, if the pressure of a blast is lower than or about the strength of FCB, there is no reduction of the peak pressure on RW, rather than a significant increase. It seems that the increase is getting relatively larger as the pressure of the blast decreases.

• Simulation of charge and structural behaviour in an tumbling mill

  Pär Jonsén, Hans-Åke Häggblad, Bertil I. Pålsson - Luleå University of Technology, Kent Tano - LKAB, Andreas Berggren - Boliden Minerals

  For a long time discrete element methods (DEM) has been used as simulation tools to gain insight into particulate flow processes. Such a process may be grinding in tumbling mills, where the mechanical behaviour is complex. To include all phenomena that occur in a mill in a single numerical model is today not possible. Therefore, a common approach is to model milling charges using the DEM assuming a rigid mill structure. To close the gap between reality and numerical models in milling, more physically realistic methods must be used. In this work, the finite element method (FEM) and the smoothed particle hydrodynamic (SPH) method are used together to model a ball mill charge in a tumbling mill. The mesh free formulation and the adaptive nature of the SPH method result in a method that handles extremely large deformations and thereby suits for modelling of grinding charges. The mill structure consists of rubber lifter and liners and a mantel made of solid steel. It is modelled with the finite element method. For the elastic behaviour of the rubber, a Blatz-Ko hyper-elastic model is used. The supplier of the lining provided experimental data for the rubber. The deflection profile of the lifters obtained from SPH-FEM simulation shows a reasonably good correspondence to pilot mill measurements as measured by an embedded strain gauge sensor. This computational model makes it possible to predict charge pressure and shear stresses within the charge. It is also possible to predict contact forces for varying mill dimensions and liner combinations.

• Simulation of Check Valve Flapper-Housing Impact Using LS-DYNA Fluid-Structure Interaction

  S. Hu (Hamilton Sundstrand Corporation)

  The flapper of a check valve in the aircraft air management system may hit the housing with a very high speed due to the sudden pressure differential caused by duct rupture, which may lead to the damage of the flapper. This event ®can be simulated using transient dynamic finite element tool, such as LS-DYNA . However, the flapper impact speed usually is unknown. The current study is focused on solving for the impact speed with the developed Fluid-Structure Interaction technology in LS-DYNA, using Arbitrary Lagrangian-Eulerian (ALE) formulation. With the aid of a concept of “Source”, “Moving Air”, and “Sink” for the ALE model, which represent the conditions of constant cabin pressure, airflow interacting with the flapper, and non-pressurized ambient environment, respectively, the proposed method successfully simulated the check valve fluid-structure interaction behavior. The predicted impact speed has an excellent agreement with the test. The developed methodology is accurate, easy to use, and applicable to all check valves regardless of size, material, and pressure differential.

• Simulation of Circular Sawing Proccesses

  H. Vazquez Martinez (Fraunhofer IPA)

  Spanende Prozesse sind durch sehr hohe Dynamik und Verformungszuständen gekennzeichnet. Mit Hilfe der Simulationstechnologie sind bereits verschiedene Zerspanungsprozesse mit guten Ergebnissen analysiert worden. Obwohl sich Kreissägeprozesse durch sehr hohe Zerspanungsleistungen auszeichnen, wurden bisher kaum Simulationen auf diesem Gebiet durchgeführt. In der folgenden Arbeit werden Simulationen von Kreissägeprozessen mit LS-Dyna durchgeführt, bei denen die Einflüsse von Prozessparametern und Schneidgeometrien untersucht worden sind. Durch die Auswertung von FESimulationen sind geeignete Modellparameter sowie Optimierungspotenziale für die Simulation von Kreissägeprozessen ausführlich dargestellt.

• Simulation of Cold Roll Forming of Steel Panels

  Fei-chin Jan, Oladipo Onipede Jr. - University of Pittsburgh

  This project uses LS-DYNA to simulate the rolling deformation of a flat steel sheet into a panel of particular shape. The process involves the gradual deformation of the steel sheet by passing it through a series of rollers at a constant speed. Each of these sets of rollers is oriented at a slightly different angle to incrementally increase the deformation of the sheet until the desired geometry is obtained in the panel. Since the sheet could be going through several different sets of rollers at the same time, the deformation process is very complex and highly non-linear. During this process, the sheet metal panel undergoes plastic deformation and develops residual stresses. Some of the problems encountered with these panels include localized buckling, undesirable local deformation at the front (head) of the panel and excessive spring back of the end of the panel (tail). These problems are also observed in the results from the simulation and methods to minimize their effect are investigated. Other issues encountered in the simulation include the contact mechanism between the moving panel and a moving roller, effect of roller size and placement, panel thickness, panel speed and roller friction. An adaptive mesh was used to efficiently mesh the plate and rollers at critical locations. The results obtained should help improve both the simulation process and the actual cold-roll-forming-process especially when new or different metals are being introduced.

• Simulation of Composite Tubes Axial Impact with a Damage Mechanics Based Composite Material Model

  Xinran Xiao - General Motors Corporation

  Composite tube axial impact is a benchmark problem measuring the predictive capability of composite crash simulation. A previous work revealed that MAT58 in LS-DYNA®, a continuum damage mechanics (CDM) composite material law based on Matzenmiller-Lubliner-Taylor (MLT) model, is inadequate in representing the unloading response of composite tubes that form continuous fronds in axial impact testing. To address the issue, two approaches have been attempted. The first one is to modify the compressive unloading response. The second one is to incorporate plasticity in a CDM framework. Both approaches were tested in an MLT theory based user material model. The modified MLT models improved the stability of the tube crush simulations and the simulation results.

• Simulation of Compression Behavior of Paper Product Using *MAT_PAPER

  Sunao Tokura (Tokura Simulation Research Corporation), Kunio Takekoshi (Terrabyte Co., Ltd.)

  Environmental pollution caused by plastic products is now a global serious problem. Plastics dumped in the ocean become into micro plastics and threaten the living environment of various organisms. In order to reduce such environmental pollution, products are being developed using paper materials with less environmental impact as an alternative to plastic products. In developing a paper product, it is necessary to design a strength suitable for the application. Therefore, accurate prediction of product strength by simulation is considered to be very important for product development. In this study, we attempt to predict the strength of paper products using *MAT_PAPER, which is a paper material model implemented in LS-DYNA®. Since *MAT_PAPER is a complex anisotropic elasto-plastic composite constitutive equation, properties of paper materials were measured, and the reliable input parameters were determined. A paper cup compression test and simulation were performed using the paper material model which was constructed from the test. As a result, a good agreement and some differences between the experimental results and the simulation results is shown.

• Simulation of Compressive ‘Cone-Shaped’ Ice Specimen Experiments using LS-DYNA®

  Hyunwook Kim (Memorial University of Newfoundland)

  A laboratory scale compressive cone-shaped ice experiments were performed, and a numerical simulation model using LS-DYNA was developed. Modified material properties were applied based on a crushable foam model (MAT 63) as the ice properties. To simulate a saw-tooth pattern which is commonly observed through experiments in ice, an additional function of failure criteria, which is maximum principal stress, was included. Results of the experimental and numerical simulation were compared and represented a good agreement. The proposed numerical simulation model was extended to a larger scale and verified.

• Simulation of Concurrent Detonation of Multiple High Explosive Charges

  L. Schwer (Schwer Engineering & Consulting Services), S. Stojko, H. Bornstein (Defence Science and Technology Group)

  A 1D spherical LS-DYNA Multi-Material Arbitrary Lagrange Eulerian (MM-ALE) model was constructed to simulate the three single charge events reported in MABS 25 manuscript P-029 Stojko, et al. (2018). These three simulations were repeated using 2D axisymmetric meshes. Multiple charge simulations were made using 2D axisymmetric and 3D models of the double and triple charge experiments. As stated by Stojko et al. “The primary purpose of the experiments was to provide a database of results for the validation of numerical modeling of the effects from multiple high explosive charges.” The model results presented in this manuscript support this statement of the data representing a valuable validation database for both single and multiple charge explosions.

• Simulation of containment-tests of fast-spinning rotors by explicit FEM

  Thomas Winter - MAN B&W Diesel, Germany, Armin Huß, Heiko Beck - Ingenieurbüro Huß & Feickert, Germany

  The objective of Containment Tests is to demonstrate that the housing of a turbocharger is of sound design and capable to satisfactorily contain fractured rotating parts inside the casing. As of yet these tests were carried out on a test bed during the type approval procedure of the turbochargers. On one hand this is very expensive and time consuming and, on the other hand, the comprehension of high-speed deformation processes is restricted as well as the possibilities for measurements and improvements are limited. Due to these reasons containment tests were simulated using the explicit finite element technique, which is implemented in the code LS-DYNA. The results of the simulations which were carried out were used to improve the performance of the turbocharger in containment safety. Regions of high loading of the structure could be identified and improved. For validation purposes a test was carried out on the test bed. The results of this test have shown excellent correspondence to calculation results of the simulation with respect to global and local deformations and the mechanical behaviour of the charger components.

• Simulation of Crack Propagation using Damage- Driven Fission Adaptivity Coupled with Element Erosion or Node Splitting

  Torodd Berstad, Cato Dørum - Structural Impact Laboratory (SIMLab) / SINTEF Materials and Chemistry, Odd Sture Hopperstad, Tore Børvik - Structural Impact Laboratory (SIMLab) / Department of Structural Engineering

  A novel method for simulation of crack propagation has been developed in LS-DYNA. The method combines damage-driven fission adaptivity and element erosion or node splitting to simulate crack propagation in the finite element mesh. A damage model is used to describe the evolution of material damage with plastic straining and fracture is assumed to occur at a critical value of the damage parameter. Coupled or uncoupled damage models may be used. Mesh refinement by fission adaptivity [1] occurs at user-defined damage levels, and further the user defines the maximum number of subdivisions. If element erosion is adopted, this happens when the critical damage level is reached within the element. When node splitting is used, multiple nodes are generated for the sibling elements and nodal values of damage are estimated. As the critical damage value is reached in a multiple node, selected bonds are released to allow for a crack to develop. The direction of the crack propagation is determined based on damage values in neighbour nodes. The method has been developed for 2D continuum elements, axisymmetric elements and shell elements. Applications of the method are shown for two cases: I) tearing of cast aluminium thin-walled profiles discretized with plane-stress elements and II) plugging of steel plates modelled with axisymmetric elements. For each case simulations with element erosion and node splitting are carried out and the results compared with experimental data.

• Simulation of Crack Propagation using Damage- Driven Fission Adaptivity Coupled with Element Erosion or Node Splitting

  Torodd Berstad, Cato Dørum - Structural Impact Laboratory (SIMLab) / SINTEF Materials and Chemistry, Odd Sture Hopperstad, Tore Børvik - Structural Impact Laboratory (SIMLab) / Department of Structural Engineering

  A novel method for simulation of crack propagation has been developed in LS-DYNA. The method combines damage-driven fission adaptivity and element erosion or node splitting to simulate crack propagation in the finite element mesh. A damage model is used to describe the evolution of material damage with plastic straining and fracture is assumed to occur at a critical value of the damage parameter. Coupled or uncoupled damage models may be used. Mesh refinement by fission adaptivity [1] occurs at user-defined damage levels, and further the user defines the maximum number of subdivisions. If element erosion is adopted, this happens when the critical damage level is reached within the element. When node splitting is used, multiple nodes are generated for the sibling elements and nodal values of damage are estimated. As the critical damage value is reached in a multiple node, selected bonds are released to allow for a crack to develop. The direction of the crack propagation is determined based on damage values in neighbour nodes. The method has been developed for 2D continuum elements, axisymmetric elements and shell elements. Applications of the method are shown for two cases: I) tearing of cast aluminium thin-walled profiles discretized with plane-stress elements and II) plugging of steel plates modelled with axisymmetric elements. For each case simulations with element erosion and node splitting are carried out and the results compared with experimental data.

• Simulation of Cure Volume Shrinkage Stresses on Carbon/Vinyl Ester Composites in Microindentation Testing

  Tom Mase, Lanhong Xu, Lawrence T. Drzal - Michigan State University

  Composites made with carbon fibers and vinyl ester have significant higher processing volume shrinkage compared to composites made with epoxies. During the curing, vinyl esters experience as much as three times the volume shrinkage as compared to epoxies (10 %Vol versus 3-4 %Vol). This difference in cure volume shrinkage may be the reason that the mechanical properties of carbon/vinyl esters are low compared to that of carbon/epoxy. Cure volume shrinkage of neat resins have been measured using a dilatometer. Interfacial shear strength (IFSS) measurements for different cure volume shrinkage were completed showing a reduction in strength as the cure volume shrinkage increased. LS-DYNA was used to model the volume cure shrinkage and resulting interface/interphase properties. Modeling results are dependent on the specific representative volume element (RVE) and boundary conditions used in the simulation. Cure volume shrinkage was modeled using a temperature drop on thermoelastic material (*MAT_ORTHOTROPIC_THERMAL). Following the temperature drop, the fiber was loaded with a rigid, spherical indenter to simulate the IFSS test (at constant temperature). Simulated resultant fiber-interphase, interphase-matrix, and fiber-matrix (in the case of no sizing) are reported as a function of cure volume shrinkage. Shearing stress distributions at the fiber-interphase and interphase-matrix are also presented.

• Simulation of Dynamic Delamination and Mode IEnergy Dissipation

  Muhammad Ilyas, Christine Espinosa, Frédéric Lachaud, Michel Salaün - Université de Toulouse

  Delamination initiation and propagation of aeronautic composites is an active field of research. In this paper we present a methodology for critical energy release rate correlation of numerical simulation and experimental data. Experiments of mode I critical energy release rate were carried out at quasi static and pseudo dynamic loading rates. Cohesive finite elements are used to predict the propagation of delamination in a carbon fiber and epoxy resin composite material. A bilinear material model is implemented via user defined cohesive material subroutine in LS-DYNA. The influence of mode I energy release rate in mixed mode loading, due to a low velocity impact, is also investigate.

• Simulation of Dynamic Delamination and Mode IEnergy Dissipation

  Muhammad Ilyas, Christine Espinosa, Frédéric Lachaud, Michel Salaün - Université de Toulouse

  Delamination initiation and propagation of aeronautic composites is an active field of research. In this paper we present a methodology for critical energy release rate correlation of numerical simulation and experimental data. Experiments of mode I critical energy release rate were carried out at quasi static and pseudo dynamic loading rates. Cohesive finite elements are used to predict the propagation of delamination in a carbon fiber and epoxy resin composite material. A bilinear material model is implemented via user defined cohesive material subroutine in LS-DYNA. The influence of mode I energy release rate in mixed mode loading, due to a low velocity impact, is also investigate.

• Simulation of Energy Absorbing Materials in Blast Loaded Structures

  Michael J. Mullin, Brendan J. O’Toole - University Nevada Las Vegas

  Energy absorbing materials such as foam or honeycomb are of interest in blast protection because of their ability to absorb energy through plastic deformation. After reaching their yield stress, these materials exhibit a region of constant stress for increasing strain until the material is completely compacted. The energy needed to crush the material is proportional to the area under the stress-strain curve. Because foams and honeycombs have this “plateau” region, they absorb a considerable amount of energy relative to their low density. These materials are investigated to determine if their energy absorbing abilities can be used to mitigate the load and shock transferred to a vehicle structure subject to blast loading. Ballistic pendulum experiments show that energy absorbing materials increase the imparted impulse from a blast. This behavior was contrary to expected results so computational models were created in LS-DYNA to understand the phenomenon that causes an increase in imparted impulse. ConWep and Arbitrary-Lagrangian- Eulerian (ALE) techniques were used in simulations to demonstrate their efficiency and accuracy. An additional ConWep aluminum foam model was created to directly compare simulations against ballistic pendulum experiments found in the literature.

• Simulation of Energy Absorption in Braided Composite Tubes through Axial Crushing

  Carla McGregor, Reza Vaziri - The University of British Columbia, Canada, Xinran Xiao - General Motors Corporation

  Modeling damage propagation and energy absorption in composite tubular structures under axial compression is a challenging task due to the complex nature of damage growth in composites. In this paper, our model (CODAM for COmposite DAMage), which is incorporated into LS-DYNA® as a user material model, is used to simulate the axial crushing response of braided composite tubes. Recent improvements to the finite element model include the addition of a debris wedge, representation of delamination using a tiebreak contact interface, and more physically based model parameters. It is shown that the damage propagation, fracture morphology and energy absorption predictions correlate well with the experimental results.

• Simulation of Falling Weight Deflectometer for In-Situ Material Characterization of Highway and Airport Pavements

  Waheed Uddin - The University of Mississippi

  Nondestructive evaluation of highway and airport pavements is performed by deflection testing, such as a falling weight deflectometer (FWD). Many agencies use FWD deflection data to backcalculate pavement moduli using subjective inputs and forcing the moduli within a pre-selected range for each material. The failure of many pavement projects can be attributed to the uncertainties in these material inputs. The use of static elastic layered analysis and two- dimensional static finite element analysis programs is inadequate to calculate pavement responses and to relate these to pavement performance. This paper presents some results of advanced three dimensional-finite element (3D-FE) computer simulations carried out on selected pavement-subgrade models of asphalt pavements, subjected to a standard FWD impact load. Good agreement is shown between simulated and measured FWD deflections. Examples of nonlinear FWD moduli for an aircraft wheel load are presented. Effects of viscoelastic material properties on pavement responses to dynamic FWD loading are discussed. The LS- DYNA contact surface definitions are applied for dynamic analysis of pavements. The paper demonstrates the use of advanced finite element dynamic analysis procedures for correctly simulating pavements subjected to dynamic loads produced by nondestructive evaluation equipment and dynamic wheel loads.

• Simulation of Flow Induced Vibrations in Pipes using the LS-DYNA ICFD Solver

  M. Timgren (DYNAmore Nordic)

  Flow induced vibrations (FIV) is an important phenomenon to understand for m-shaped jumpers which are used in offshore applications. To understand how the FIV affects the life time of a m-shaped jumper FSI simulations have been used. Many papers have investigated two-phase flow in m-shaped jumpers and performed FSI simulations to understand how the flow affects the movement of the pipe. No or little information is available on how big impact the two-phase flow has compared to the case with one fluid. This paper will perform FSI simulation of a m-shaped jumper with one fluid in LS-DYNA, water, and compare the results with other studies with two-phase flows.

• Simulation of Fluid-Structure Interaction between Injection Medium and Balloon Catheter using ICFD

  L. Wiesent, M. Wagner(OTH Regensburg)

  Arteriosclerosis is a major health issue worldwide. While it is commonly treated by the implantation of an balloon-expandable stent, micro injuries may occur during stent deployment, and induce in-stent restenosis, whose consequence can be fatal. Studying this undesirable phenomenon is usually limited as experimental data is hard to obtain on ethical ground. Numerical simulation are performed to better understand this problem. To construct a more realistic simulation of a balloon-expandable stent, a partitioned strongly-coupled FSI simulation of the balloon deployment was set up using the ICFD solver of LS-DYNA, - a quite innovative approach. The complex balloon configuration as well as the interaction of the injection medium and the balloon structure was considered. The balloon structure consisting of shell elements was obtained from preliminary balloon folding and pleating simulations. The balloon consists of a flexible thin walled polyamide. The injection fluid is implemented using volume elements. Balloon deployment was initiated by a pressure boundary condition inducing a volume flow into the balloon. The initial feasibility analysis showed promising result including a continuous balloon deployment and a reasonable development of the fluid pressure and velocity field. However, applying this FSI approach to a more complex balloon structure led to a non convergent solution. The non-convergence could be mainly reduced to mechanical factors including the low wall thickness of the balloon (< 0.05 mm) and the flexibility of the polyamide. Further, the ICFD solver shows less accuracy concerning the FSI conditions when dealing with thin flexible structures as well as enclosed volumes. A shell thickness of 0.06 mm is believed to result in a convergent solution. Based on these findings, a more detailed examination of the convergence issues and their possible solutions can be explored as future works. The work presented in this thesis is believed to innovative, and provides a promising approach to a realistic FSI simulation of a balloon-expandable stent.

• Simulation of Forming of Paperboard Packaging using LS-DYNA

  M. Schill, J. Karlsson (DYNAmore Nordic), J. Tryding (Tetra Pak)

  Paperboard is widely used as a package material for food and beverage. The ability to simulate the forming of the packages is of great interest, due to the variety in shapes and paperboard material structure combined with production speed. T

• Simulation of full-scale seismic-resistant structural frame tests using LS-DYNA 960 Implicit Solver

  CAROLINE J.FIELD - Ove Arup & Partners

  This paper focuses on the finite element simulation of two full-scale tests of high performance, seismic-resistant structural frames using the LS-DYNA 960 implicit solver. The frame was physically tested as part of the design validation for the new Stanley Hall building on the University of California Berkeley Campus. The pseudo static non-linear analyses, showed excellent correlation with the measured test data. Two sequential tests were performed on the same frame but with different brace configurations, hence residual stresses and strains, and the process of brace replacement were important. This work illustrates the convenience of implicit LS-DYNA for structural applications – transferring this technology to the built environment. It also provides confidence in and verification of the software. The construction industry tends to shun non-linear analyses, deeming them too complicated; however it is ideal and indeed, essential for seismic applications. This simulation provides an alternative approach to full-scale testing for the future evaluation of this type of structure. It also provides the opportunity for the development of new and improved structural details as well as the retrofit assessment for existing structures.

• Simulation of Granular Ceramic Armor Under Impact from Bullets

  James G. McLean, Seth Frutiger, Robert Dabek, Jeremy Reeves - State University of New York at Geneseo

  Ballistic impact is studied for a novel form of armor, granular ceramic armor. Ceramic granules, in the millimeter size range, are closely packed and bonded together using a relatively soft polymer. This composite layer rests on a rigid backing. In field tests such panels have already shown the capability to stop armor piercing rifle rounds. The goal of the study is to determine the detailed mechanisms of energy and momentum dissipation. Because of the granular structure, the armor performance depends on the exact impact position. We are particularly interested in determining the weakest points for further design improvements. Mapping of exit velocities indicates that some of the stronger and weaker points are at surprising impact positions due to grain tumbling.

• Simulation of High-Voltage Discharge Channel in Waterat Electro-Hydraulic Forming Using LS-DYNA®

  V. Mamutov (St. Petersburg State Polytechnical University), S. Golovashchenko (Ford Motor Company), A. Mamutov (Oakland University)

  The method of simulating of expansion of plasma channel during high-voltage discharge in water at electro-hydraulic forming (EHF) is developed using finite-element software package LS-DYNA® 971. The energy input into the plasma channel from the discharge circuit is taken into account. The energy deposit law is calculated from the experimentally obtained pulse current and voltage in the discharge circuit measured between the electrodes. The model of discharge channel is based on assumption of adiabatic channel expansion when the energy introduced into the channel from the external electrical circuit is only spent on increasing the internal energy of plasma and on the work of plasma expansion. Water is simulated as an ideally compressible liquid with bulk modulus of K = 2.35 GPa. The cavitation threshold for the liquid is defined as 0.1 MPa. The interaction between the channel and the water is simulated using Arbitrary Lagrange Eulerian (ALE) technique. The deformable blank is simulated using shell elements. The results of simulation of two variants of the discharge chamber are presented: for the long cylindrical chamber with long axisymmetrical discharge channel and for the compact chamber of arbitrary shape with short discharge distance. The developed numerical method is verified by comparing the results of simulation with the results from the test simulation, which is a one-dimensional axisymmetric finite-difference based problem with the same parameters. It is also verified by comparing the results of simulation and the experimentally measured pulse pressure in the discharge chamber with a known function of energy input.

• Simulation of Hollow Embossing Rolling for Bipolar Plate Forming using LS-DYNA©

  Franz Reuther, Verena Psyk, Verena Kräusel, Martin Dix

  Hollow embossing rolling constitutes a promising forming technology for metallic bipolar plates due to the high achievable production rates. The simulation-based process optimization is impeded by the incremental forming character and modeling of fine channel structures, which leads to large model sizes and computation times. This paper presents a shell-based finite element modeling approach using LS-DYNA© for bipolar plate forming simulation. Essential boundary conditions of the modeling are discussed, and recommended setting parameters are derived.

• Simulation of Hot Plate Rolling using LS-DYNA©

  M. Schill, J. Karlsson (DYNAmore Nordic), H. Magnusson, F. Huyan (Swerim), N. Safara Nosar, Jonas Lagergren, T. Narström (SSAB)

  Creating a virtual model of a hot plate rolling process involves many challenges. In an attempt to address these, a research project called FINBEAM (“Full Scale Integrated Workability Modelling”) was initiated by Jernkontoret and the Swedish steel industry, financed by the Swedish innovation agency, VINNOVA. The purpose was to bring research institutes, industry and software developers together to reach a common modeling ground for simulation based design of hot working processes for the steel industry in Sweden.

• Simulation of Hydrodynamic Ram and Liquid Aeration

  S.C.McCallum, D.D.Townsend - BAE SYSTEMS

  During the past several years, research within BAE SYSTEMS has concentrated on developing a capability for simulating Hydrodynamic Ram (HRAM). In this paper we demonstrate how the ALE technique in LS-DYNA can be used to simulate the principal stages of HRAM with liquid aeration. LS-DYNA is used to simulate the impact of a small steel sphere at 2km/s into a water-filled container manufactured from 3.2 mm thick aluminium alloy L165. The simulation results are compared with laboratory experiments from a two-stage gas-gun facility showing close agreement with peak pressure and impulse values. In additional simulations, aeration is modelled using an effective equation of state, which describes the compressibility of the water (on a macro-scale) inside the container. The simulation results show that aeration can be used to alleviate the shock wave that forms ahead of the projectile in order to reduce damage on the surrounding structure.

• Simulation of ice action loads on off shore structures

  Dr. Daniel Hilding , Dr. Jimmy Forsberg - Engineering Research Nordic AB, Dr. Arne Gürtner - Statoil ASA

  During the last years, there has been an increasing amount of work published regarding simulation of ice action on structures using finite element models of the ice. The effect of ice fracture is in these models approximated using cohesive elements. In this article we give an overview of the cohesive element method for ice modelling including recent improvements made by the authors. A description is given of the implementation of the cohesive element method for modelling floating ice sheets in LS- DYNA including effects such as buoyancy. To demonstrate the performance and robustness of the implementation, numerical results are presented from a full scale simulation of an ice sheet impacting an offshore structure.

• Simulation of Impact Proof Testing of Electronic Sub-Systems

  P. Glance (Naval Air Warfare Center Weapons Division)

  The purpose of this paper is to document the development of a new simulation tool which is being employed to simulate the deceleration vs. time pulse imposed on electronic systems during impact tests as shown in Figure 1. The simulation tool has also been employed to predict the stress, strain, fracture, and structural failure of electronic sub-systems. Cannon tests and rocket propelled sled tests are the standard test methods employed to “proof test” the successful operation of hardened electronic systems under extreme operating conditions. The proof test consists of placing the electronic sub system into a generic steel carrier and launching into concrete or soil blocks. The peak deceleration is determined by the lower stiffness material which is the concrete / soil. Previous LS-DYNA and “Hydrodynamic” code simulations of these tests required super computers, expert consultants, extensive computer run times, and relatively high cost. The new LS-DYNA concrete material model (*MAT 159) with eroding contact option, allows rapid simulation of impact penetration and by-passes the need for excessive computer run times often required for Arbitrary Lagrangian Eulerian (ALE) LS-DYNA models and equation of state (EOS) material models. This paper describes a simple, robust, and fast running, LS-DYNA application for simulating high g cannon and sled tests. This application will run on a Dell workstation employing one Intel processor and accurately predicts; deceleration, stress, strain, fracture, and overall deformation and damage of electronic systems

• Simulation of Loads from Drifting Ice Sheets on Offshore Structures

  D. Hilding, J. Forsberg (DYNAmore Nordic AB), A. Gürtner (Statoil ASA)

  In later years, there has been an increasing amount of work published regarding simulation of ice action on structures using finite element models of the ice. Here we will present results from a method development project aimed at evaluating the feasi- bility of full scale simulation of ice action from drifting ice sheets on offshore structures. The used methodology is presented including new developments, the implementation in LS-DYNA®, and results from a benchmark study where simulation results are compared with full scale meas- urements of ice forces. The methodology is based on using the cohesive element method for modeling the ice fracture in conjunction with an ad hoc homogenization method developed by the authors. The homogen- ization method is used to capture sub element size cracks in a cost efficient manner.

• Simulation of Masonry Wall Failure and Debris Scatter

  Stuart C. McCallum, BAE Systems - ATC (Filton), Paul M. Locking, Steve R Harkness, BAE Systems - Land (Shrivenham)

  This paper outlines a methodology for the simulation of masonry wall failure and debris scatter. The aim of this work is to develop simulation techniques which can be used to assess and improve the design of building structures subject to high explosive loading. Masonry walls are constructed from bricks that are modelled as individual parts with tiebreak and single surface contact types. A key requirement of this work is to accurately predict the final landing position and scatter pattern of any bricks. If the acceleration of a separated brick is significantly high, the trajectory and final landing position of the brick will be influenced by air-drag. In this work we simulate the air-drag force using a user FORTRAN subroutine and demonstrate its accuracy with comparison to theory. The strength of the mortar-masonry brick bond is validated by comparison with laboratory experiments conducted in previous work showing close agreement. A series of simulations are then presented which demonstrate the failure and debris scatter of a simplified building structure.

• SIMULATION OF NONLINEAR VISCO-ELASTICITY

  Kazuyoshi Miyamoto, Hiroshi Yoshinaga, Masaki Shiraishi, Masahiko Ueda - Sumitomo Rubber Industries,LTD.

  CAE has been applied for the development of various industrial products in many kinds of fields. They are not only products made of metals but also products made of polymeric materials, such as tires, balls for various kinds of sports, press ink rolls, and so on. These materials, such as rubber and synthetic resin have viso-elastic properties. And most of them have nonlinear characteristics. In case of dealing with them, it is very important for accurate simulation to apply nonlinear visco-elasitc material models. Especially it is necessary in the field of Impact. Because impact is in the condition of large strain, or high-speed strain rate, performances as products depend on nonlinearity. Therefore it is not reasonable for the simulation of impact to input material properties measured by visco- elastic spectrometer well known as a typical visco-elastic measurement. They are in the condition of small strain on the order of few percent and low strain rate on the order of a few [/s]. It is necessary to measure them in large strain on the order of more than ten percent and high strain rate on the order of thousands [/s] same as practical condition. However there had not been any testers to measure viso-elastic material properties in the condition of large displacements and high deformation rates before. Recently, the split Hopkinson pressure bar, which is originally for evaluation of metals, has been improved for evaluation of polymeric materials. And material properties of some polymeric materials in that condition have been evaluated. In this study, a nonlinear visco-elastic material model is developed by using the measurement results from the improved split Hopkinson pressure bar. Further, the tests of the split Hopkinson pressure bar are simulated, and good correlation with the experiment is obtained. Finally the restitution tests of golf ball is simulated as an example of application. Agreement between the experiment and the simulation is confirmed.

• Simulation of Overhead Crane Wire Ropes Utilizing LS-DYNA®

  Andrew Smyth, P.E., LPI, Inc., New York, NY, USA

  Overhead crane wire ropes utilized within manufacturing plants are subject to extensive cyclic loading due to near continuous service operation. An LS-DYNA model was developed to assist in determining the expected fatigue life of the crane wire ropes by calculating both the dynamic cyclic stress and the total number of bending reversals per lift.

• Simulation of Process Dependend Properties with MAT_254 Demonstrated for the ‚Bake-Hardening‘ of an 6xxx Aluminum Alloy

  M. Merten, T. Klöppel (DYNAmore), S. Jurendic, Z. Liang (Novelis)

  Taking into account the strain and thickness distributions of cold formed parts is well established in LS-DYNA. Additionally, *MAT_TAILORED_PROPERTIES offers the possibility to use a tabulated set of flow curves dependent on a history variable. The physical quantity represented by the chosen history variable can be defined by the user. Getting the distribution of this history variable may be a difficult task. For press-hardening simulation exclusively, LS-DYNA offers *MAT_244/248 to calculate the distribution of mechanical properties based on the distribution of metallurgical phases. The phase distribution is a result of the thermo-mechanically coupled simulation of the production process. To overcome the limitations of these two material models, *MAT_GENERALIZED_PHASECHANGE was implemented. This material has been used successfully for the simulation of press-hardening, welding and 3D-Printing. The current work presents a new field of application for *MAT_GENERALIZED_PHASECHANGE, simulating the “bake-hardening”-effect of specific aluminium alloys. The local final strength of hardenable aluminum alloys for automotive applications depends on the local pre-strain from the forming process and the local time-temperature-profile during paint bake. An initial approach to model this behavior is given. Implemented extensions to *MAT_GENERALIZED_PHASECHANGE, which enable are more precise description of the underlining mechanisms, will be shown.

• Simulation of Progressive Damage Development in Braided Composite Tubes Undergoing Dynamic Axial Crushing

  Carla McGregor, Reza Vaziri, Anoush Poursartip - The University of British Columbia, Canada, Xinran Xiao, Nancy Johnson - General Motors Corporation

  Composite tubular structures are of interest as viable energy absorbing components in vehicular front rail structures to improve crashworthiness. Desirable tools in designing such structures are models capable of simulating damage growth in composite materials. CODAM (COmposite DAMage), which is incorporated into LS- DYNA as a user material model, is a continuum damage mechanics based model for composite materials with physically based input parameters. In this paper, the CODAM model is used to simulate tube crush experiments. It is shown that the damage propagation, fracture morphology and energy absorption predictions correlate well with the experimental results.

• Simulation of Progressive Deformable Barrier (PDB) Tests

  Chung-Kyu Park, Seong-Woo Hong, Pradeep Mohan, Richard M. Morgan, Cing-Dao (Steve) Kan - The George Washington University, Kisu Lee, Shinhee Park, Hanil Bae - Hyundai Motor Co. & KIA Motors Corp.

  This paper describes the Finite Element (FE) model development of the Progressive Deformable Barrier (PDB). The FE model of the PDB incorporates shear tearing effect and air pressure effect of the honeycomb in the PDB. The developed PDB is used in several vehicle-to-PDB simulations to check its robustness. Five different makes and models of passenger vehicles are selected for the simulation of PDB tests. Finally, the aggressiveness of these vehicles is presented based on the simulation results.

• Simulation of proposed FMVSS 202 using LS-DYNA Implicit

  Vikas Patwardhan, Babushankar Sambamoorthy, Tuhin Halder - Lear Corporation

  Federal Motor Vehicle Safety Standard 202 applies to automotive seat head restraints, and their attachment assemblies. The regulation is aimed at reducing the frequency and severity of neck injuries due to huge forces resulting from vehicle crashes. The main objective of this paper is to discuss the LS-DYNA IMPLICIT code vis-à-vis the simulation of the proposed FMVSS 202 regulation. The proposed changes to the FMVSS 202 standard incorporates a permanent set requirement for the head restraints. Since a quasi-static FE simulation cannot do permanent set calculations, LS-DYNA IMPLICIT code was used for this purpose. The paper explains in detail about the setting up of a seat model for the test, the various modeling techniques used and the correlation of results for the seat model.

• Simulation of Reinforced Concrete Structure under Impact Loading using Meshfree Cohesive Failure Approach

  H. S. Lu, J. Y. Zhao (Shanghai Hengstar Technology Co), X. W. Wang, X. Lei (Shanghai Nuclear Engineering Research and Design Institute), C. T. Wu (LSTC), Y. C. Wu (Karagozian & Case)

  Reliable numerical simulation of failure is important for the design and planning of new solids and structures, as well as for the safety assessment of existing ones. In the past two decades, gradient and non-local models for regularizing loss of ellipticity due to material failure using non-standard finite element method and more recently the meshfree method have been the topic of considerable research. Alternatively, discontinuous partition of unity enrichments and meshfree visibility concepts were proposed and used in finite element method (also called extended finite element method - XFEM) and meshfree method to model cracks. Due to the fact that the description of crack plane in XFEM using level set method still presents several difficulties in the three-dimensional simulation of solids, the meshfree method using visibility concept is tested for the solid failure analysis of reinforced concrete structure under impact loading. The current method incorporates the discontinuous field into the generalized meshfree approximation [1] by the introduction of visibility approach [2]. To determine the onset of fracture and subsequently the crack propagation, a stress-based initial-rigid cohesive cracking model was developed for the brittle and semi-brittle materials. After the insertion of new crack, the state variables are interpolated and transferred to the new stress point using second-order meshfree approximation [3]. To integrate the discrete equations involving the crack plane, the strain smoothing algorithm developed in SCNI method [4] was adopted in this development. A typical reinforced concrete structure under impact loading failure involving multi-cracks is modeled using the developed method and results are presented.

• Simulation of residual deformation from a forming and welding process using LS-DYNA®

  Mikael Schill (DYNAmore Nordic AB), Eva-Lis Odenberger (Industrial Development Centre in Olofström AB)

  Predicting the finished geometry of a part is a major issue for the manufacturing industry. This is a complex task, especially if the manufacturing involves several types of processes. In order to succeed, the complete manufacturing process has to be included in the simulation. For sheet metal forming, this has been done for quite some time where trimming, forming and springback are simulated in consecutive order. However, there are other manufacturing processes which affect the geometry of the finished part. In this paper, a welding process is added to the manufacturing process chain. The welding simulation is done using the novel material model *MAT_CWM with ghost element functionality. The aim of the paper is to investigate how the different process stages affect the final geometry of the part and how this is efficiently and accurately simulated with LS-DYNA. Further, an attempt is made to improve the part tolerance by springback compensation of the forming tools accounting for deviance from both springback and weld deformation.

• Simulation of Self-Piercing Riveting Process and Joint Failure with Focus on Material Damage and Failure Modelling

  A. Rusia (Daimler/University of Stuttgart), M. Beck (Daimler), Prof. S. Weihe (University of Stuttgart)

  Weight reduction is one of the main objectives that has played a pivotal role in designing Automobiles in the past decades. Various methods can be employed in this direction such as replacing traditional steel with lightweight aluminum alloys or using a combination of multiple lightweight materials. Joining techniques like spot welding, which generally perform well for joining of steel body panels, do not yield satisfactory results in joining of aluminum sheets. Consequently, there has been an increasing interest in developing alternative joining techniques as a replacement for spot welding in the automotive industry.

• Simulation of Self-Piercing Rivet Insertion Using Smoothed Particle Galerkin Method

  Li Huang, Shiyao Huang, Materials and Process Research, Ford Motor Research and Engineering Center;, Youcai Wu, Livermore Software Technology Corporation;, Garret Huff, Andrey Ilinich, Amanda Freis, George Luckey, Research and Advanced Engineering Center, Ford Motor Company

  Self-piercing rivets (SPR) are efficient and economical joining elements for lightweight automotive body structures. In this paper, a meshfree Smoothed Particle Galerkin (SPG) method was applied to the simulation of the SPR insertion process. Two layers of aluminum alloy 6111-T4 were joined using a full three-dimensional (3D) model with LS-DYNA® explicit. The severely deformed upper sheet was modeled using the SPG method with activated bond failure, while the rest of the model was modeled using the traditional finite element approach. An extensive sensitivity study was conducted to evaluate the proposed approach, including bond failure criteria, kernel update frequency, kernel support size, mesh refinement, et

• Simulation of Sheet Metal Forming using Elastic Dies

  M. Schill (DYNAmore Nordic), J. Pilthammar, M. Sigvant (Volvo Cars), V. Sjöblom, M. Lind (Blekinge Institute of Technology)

  Simulation of sheet metal forming is one of the major applications of LS-DYNA. Today, a majority of the forming industry is using Finite Element models to design the stamping dies in order to prevent excessive thinning, wrinkling and producing parts within tolerance by compensating for springback deformation. All these simulations are made using the assumption of rigid forming surfaces. Depending on the type of press, tool design and sheet metal part, this assumption could prove to be incorrect which yields a forming result that depends on the elastic deformation of the stamping die and in some cases the entire stamping press. Such deformations are usually compensated during die try-out by manual rework which is costly and time consuming.

• Simulation of Sheet Metal Forming Using Solid Elements using ANSYS LS-DYNA©

  Mikael Schill, Xinhai Zhu

  Simulation of sheet metal forming has long been a fundamental application of ANSYS LS-DYNA, predominantly relying on shell elements under a plane stress assumption. While effective in many cases, situations arise where a full 3D representation becomes imperative, particularly when modelling thicker sheets or parts with tight radii. However, transitioning from shell to solid elements poses immediate challenges related to e.g. element size and the simulation model size.

• Simulation of Sheet Metal Forming – New Developments

  Dr. M. Fleischer, C. Babel, M. Guru, Dr. J. Strauß-Ehrl

  The use of finite element (FE [12], [16]) simulations to conduct a virtual validation of the forming process for sheet metal parts has been introduced in the mid 1990s and is state of the art in the automotive industry today. Two challenging tasks for determination of feasibility of a tool design and its process parameters [17] are the prediction of the material behavior during the forming process and the springback of the final part [2,3,4].

• Simulation of shock absorbers behavior during a 9m drop test

  Fabien Collin - TN International

  TN International designs, manufactures and licenses packages for the transportation of radioactive materials. To justify the leaktightness and then insure the safety of a package during an accident event, a 9m drop test onto an unyielding target has to be considered. The corresponding kinetic energy is generally absorbed by shock absorbers filled with wooden blocks. In order to improve the numerical simulation of those shock absorbers, a benchmark has been performed using a specific drop test exhibiting an important crushing. This study has led to the improvement of the wood material law, including shear damage effect. The welds failure was also implemented to improve results. This paper will show the main results of this study.

• Simulation of Shock Wave Mitigation in Granular Materials by Pressure and Impulse Characterization

  C. Guéders, J. Van Roey, J. Gallant, F. Coghe - Royal Military Academy, Brussels

  The detonation of an explosive charge has two major effects, blast wave generation and fragmentation. New technologies of energy dissipation, based on granular materials, seem to have good shock attenuation capabilities. Plastic deformation, brittle fracture and comminution are different mechanisms of dissipation which can take place in granular media, allowing blast energy absorption and reduction of dynamic solicitation applied on structures. Dynamic solicitation of structures is determined by the reflected pressure in a quasi-static loading case or by the reflected impulse in an impulsive loading case. Blast pressure and impulse damping represent in a macroscopic way the effects of energy dissipation mechanisms appearing in granular materials. Material efficiency can be determined by the study of the attenuation of these two parameters. Vermiculite, a porous crushable material and CRUSHMAT®, a ceramic granular material made of alumina have been tested. Blast impulse amplification has been observed with thin layers of vermiculite while with CRUSHMAT® only attenuation has been observed. Efficiency stagnation has also been noticed for thick layers of CRUSHMAT® in which pressure and impulse, after being passed through the sample’s upper part, seem to be too low for further attenuation in the lower part of the layer. LS-DYNA has been used to simulate the experimental setup in which reflected pressure and impulse measurements have been realized on the different samples. The simulation model has been developed for a better understanding of pressure and impulse decrease, dissipation mechanisms and macroscopic behaviour of granular materials when they are subjected to blast. The CRUSHMAT® stress-strain curve has been optimized with LS-OPT trying to allow a better correlation between simulations and experimental observations.

• Simulation of Short Fiber Reinforced Plastics in LS- DYNA® Using Envyo® Mapped Fiber Orientations Obtained from Process Simulation in Moldex3D®

  M. Gustavsson, D. Aspenberg (DYNAmore Nordic), B. Stoltz (IKEA)

  Accurate representation of materials is an essential part of the quest for realistic and predictive simulation, not least for anisotropic materials such as short fiber reinforced plastic (SFRP). Still, it is common to neglect the anisotropic properties of SFRP components when evaluating the structural performance of the design in FE simulation, thereby often failing to predict a realistic mechanical behavior. Neglecting the anisotropic features of SFRP, especially at an early stage in the design development, may lead to a design that is not viable for the component in question.

• Simulation of Structural Latches in an Automotive Seat System Using LS-DYNA

  Tuhin Halder - Lear Corporation

  Latches play an increasingly vital role in an automotive seat system due to the recent introduction of the mandatory 3-point restraint system for center occupants. Traditionally, latches were designed to carry the seat back load, the head restraint load, and the luggage intrusion load. For the new Seat Integrated Restraint (SIR) systems, latches have to meet a very high load requirement with a very low range of allowable displacement. Hence, a latch has to meet its basic function, which is to fold and tumble, and it has to pass this stringent non-linear loading condition. Finite Element Analysis (FEA) has been widely used to simulate latches on a component level. With the introduction of the displacement requirement limitation for the SIR retractor, component level analysis is redundant. The paper discusses an efficient new method to simulate the seat system along with latches that yield meaningful results and a consistent level of correlation.

• Simulation of the Braiding Process in LS-DYNA®

  Seyedalireza Razavi, Lorenzo Iannucci, Imperial College London, Department of Aeronautics, London, UK

  Textile braids and the over-braiding manufacturing technology have been attracting a lot of recent interest, particularly in the aerospace and automotive industries, in response to increasing demands for a low cost manufacturing process to produce high-performance composites. The application areas extend from the over-braided structural components of super-cars (e.g. Lamborghini Aventador) to 2D and 3D triaxial braided composite fuselages, wings, and circumferential frames of the transport aircraft. Thus with such potentials, it is essential to use virtual simulation tools to predict final mechanical properties of the textile preforms through resembling the actual braiding process condition before the part is physically fabricated.

• Simulation of the Crash Performance of Crash Boxes based on Advanced Thermoplastic Composite

  Matthias Hörmann - CADFEM GmbH, Germany, Marco Wacker - Jacob Composite GmbH, Germany

  Because of their superior mechanical properties in combination with a relative low density Fiber Reinforced Composites (FRC) are of great potential in the area of lightweight structures respectively applications. Consequently FRC is gaining influence and acceptance not only in the automotive industry. Unfortunately the application of endless reinforced composites with duroplastic matrix was mainly restricted by a production technique unsuitable for a full production run. Up to date it was only possible for short and long fiber reinforced duroplastic SMC (Sheet Molding Compound) and thermoplastic GMT (Glass Mat Reinforced Thermoplastic). Compared with conventional reinforced duroplastics the continuous reinforced thermoplastic composites (Advanced Thermoplastic Composites) have the capability for a full production run in terms of a thermoforming procedure (see Figure). With this technique Jacob Composite and partners were able for the first time to deliver fiber reinforced composite bumper beams in a number of 50.000 pieces/year for the automotive industry.

• Simulation of the Electromagnetic Flux Compression using LS-DYNA Multi-Physics Capability

  K. Takekoshi (Terrabyte)

  The Electro-Magnetic Flux Compression system can generate ultra-high magnetic flux over 700 T with an electromagnetically imploded coil and is employedto study electronic physical properties of condensed matterssuch as carbon nano-tubes.Predicting the generation of electro-magnetic flux using computer simulation techniquesrequires electro-magnetic –thermal –structural coupling analysis. Since the electromagnetism (EM) module has been introduced into LS-DYNA starting from Ver. R7.

• Simulation of the forming process of the Metal-Plastic-Metal sheets

  Dr. R. Borg - Engineering Research Nordic AB

  Metal-Plastic-Metal (MPM) sheets consists of two metal sheets bonded together by a thin polymer layer. Modelling this sheet structure with a single shell element gives a too stiff response. The large shear deformation in the polymer layer can not be represented correctly. A method is presented on how to simmulate the forming process of MPM-sheets by which the two metal sheets are modelled with two layers of shell elements. The bonding polymer is not modelled as elements. Instead its effect on the structure is implemented as a Tie-Break contact algorithm. The shell thickness is necessarily accounted for in this contact interface such that the midsurfaces of the metal plates are possitioned correctly with respect to each other. Results from simulations and experiments are examined and forming criteria such as wrinkling, necking and failure are discussed.

• Simulation of the high velocity impact of railway ballast on thermoplastic train underbody structures

  M. Vinot, D. Schlie, T. Behling, M. Holzapfel (DLR)

  Railway transportation represents an environmentally friendly alternative to automotive transportation for long distance travel. In the project Next Generation Train of the DLR, new railway solutions are developed for passenger and freight transportation for a broad range of applications (intercity, cargo, long distance). Specifically, the high-speed train NGT HST aims at reducing travel times and specific energy consumption with new technologies. At the maximal operating speed of 400 km/h, the coupling of mechanical and aerodynamical forces leads to increasing risks of ballast stone impact on the train structures (in particular underbody structures), thus threatening primary components underneath [1]. Through the repetition of stone impacts during the entire lifetime of a structure, critical damage can occur and reparation or replacement concepts are required. The present work aims at investigating an impact-resistant underbody structure made out thermoplastic composite materials for the HST train on numerical and experimental basis. By considering multiple impact scenario in the structure sizing process, the project intends to reduce the interval at which the structure has to be replaced.

• SIMULATION OF THE IMPACT ON GROUND OF AIRDROP LOADS TO DEFINE A STANDARD WORST CASE TEST

  Yves de Lassat de Pressigny, Thierry Baylot - Centre d’Essais en Vol, Ministère de la Défense, France

  The French Flight Test Centre in Toulouse (CEV Tl) made in 2004 prototype simulations of ground impact after airdrop (2d-40, 5th European LS-DYNA users conferences.) Its purpose was to enable the test centre to achieve parametric analyses of the shock level produced by airdrop with a combination of simulation and real tests, which was not feasible with tests only (because of the number of test cases required). Indeed a first proposal with several hundreds test cases had been rejected by the French Army Headquarters because of its high cost and length. An alternate solution with about a hundred simulation results and fifty four life tests was finally accepted and realised throughout 2005 and 2006. LS-DYNA was used to demonstrate what were the cargo fitting techniques and impact conditions that could produce the highest shock levels with the current state of airdrop technology. This gave the experts early hints in their purpose to design a standard test case to assess weapon systems reliability after airdrop. The testing campaign afterwards was focused on checking key points of the simulation analysis and evaluate the importance of non deterministic effects that could not be simulated, which is needed to estimate the actual value of the future standard qualification test for airdrop.

• Simulation of the Manufacturing Process of Self-Piercing Rivets with LS-DYNA with Focus on Failure Pediction for Sheets and Rivet

  M. Buckley (Jaguar Land Rover), H. Gese, M. Reissner, G. Oberhofer (Matfem Partnerschaft)

  There are many two-sheet and three-sheet material combinations in a body-in-white which can be joined via self-piercing rivets (SPR). A physical trial-and-error approach to ensure the feasibility of all combinations would be very time consuming and expensive. In addition the physical manufacturing test will not deliver the amount of accumulated damage in the sheets which is relevant for the strength of the SPR in a successive crashworthiness load case. An appropriate virtual simulation of the manufacturing process can be used to assess manufacturability and to evaluate the accumulated damage.

• Simulation of the Performance of Passenger Rail Vehicles under Blast Conditions in LS-DYNA®

  Francois Lancelot, Ian Bruce, Devon Wilson, Kendra Jones, Arup, Przemyslaw Rakoczy , Transportation Technology Center Inc.

  The protection of the national transportation systems in the face of increasing terrorist threats is of critical importance. Arup North America Ltd (Arup) and Transportation Technology Center, Inc. (TTCI) have been contracted to conduct research to quantify the vulnerability of railcars and infrastructure to damage caused by the use of explosives. The main objectives of this ongoing research program is to develop tools to evaluate the performance of existing railcar structures, develop potential mitigation measures for current railcars, and investigate advanced security systems for future designs under blast conditions.

• Simulation of the Temperature Distribution in Ship Structures for the Determination of Temperature- Dependent Material Properties

  J. M. Kubiczek, H. Herrnring, L. Kellner, S. Ehlers (TUHH), R. Diewald (TÜV NORD EnSys)

  Several Arctic waters are no longer ice-covered throughout the year. As a result, the Northern Sea Routes are getting into the focus of the maritime industry [1]. In addition less ice coverage in other sea areas such as the Baltic Sea leads to increased shipping traffic in the winter season. This repeatedly leads to damages to ships when sailing in ice-covered waters, but also when colliding with ice floes and icebergs but also with ships, such as icebreakers, in convoys [2, 3]. It is of great importance for the structural simulation of these events to model the material properties of the ship structure under consideration of the environmental conditions. These material properties such as yield strength and tensile strength as well as fracture strain, however, are strongly influenced by the material temperature [4]. Therefore the question arises how cold a ship structure can actually become in winter and in arctic waters and how this affects the structural response in the event of a collision. In the rules and guidelines of the classification societies -60 °C can be found as the lowest temperature for material tests on steels used in shipbuilding [5]. This value corresponds well with different temperature measurements where extreme values below -50 °C were measured in the area of the Northern Sea Route [6, 7]. In contrast, liquid seawater cannot become colder than -2 °C [8]. If the interaction with ice is considered, the structural temperature in the waterline area is of particular interest. It is influenced by both water and air temperature. Therefore, the structure temperature is estimated by thermal simulations in order to determine suitable temperature depended material curves and to predict the influence on the structural response in the collision scenario.

• Simulation of thermoplastic 3D-printed parts for crash applications

  Mathieu Vinot, Lars Bühler, Tobias Behling, Martin Holzapfel, Nathalie Toso

  The rapid development of additive manufacturing techniques in aeronautic and automotive industry opens new possibilities in the design of metallic or composite parts compared to traditional subtractive processes. In particular, 3D printing allows the design of complex parts with a high lightweight potential through optimal use of material along the load paths. In the composite field, various printing techniques emerged in the last decade such as Selective Laser Sintering (SLS) or Fused Deposition Modelling (FDM) [1]. On the downside, 3D printing is confronted to the large influence of process parameters on the geometrical and optical quality as well as on the mechanical properties of the manufactured structures [2]. Moreover, simulation techniques with finite-element methods are still at their very beginning and improvements should be achieved to predict structural performances in crash applications.

• Simulation of Various LSTC Dummy Models to Correlate Drop Test Results

  Ken-An Lou (ArmorWorks), David Bosen, Kiran Irde, Zachary Blackburn (ShockRide)

  Hybrid III Anthropomorphic Test Dummy (ATD) is primarily validated for frontal impacts from physical sled tests in an automotive incident but not for a military vehicle incident related to mine blast vertical impacts. Vertical drop tests were conducted using Hybrid III 50th percentile ATD. The purpose of conducting these tests was to identify which LSTC dummy model shows the best correlation with the test results. This paper presents the modeling correlation between LSTC’s 50th percentile RIGID, FAST, and DETAILED dummy models. A rigid seat without seat cushion was used in the drop tests so the surroundings the dummy interacted with during the test were very predictive. A total of three drop tests from the same drop height were completed to ensure consistency and repeatability of the test data. The simulation was correlated to the test data for occupant responses.

• Simulation of viscoelastic two-phase flows with LS-DYNA ICFD

  Z. Solomenko, F. Del Pin, I. Caldichoury

  Simulations of viscoelastic flows are presented. Viscoelasticity is accounted for by solving a constitutive equation for the conformation tensor - the viscoelastic stress tensor is directly related to the conformation tensor [1] and the divergence of the viscoelastic stress tensor yields an extra momentum source. The Oldroyd-B constitutive model is here considered [1]. Results of several benchmark tests are presented. Implementation is first tested on a two-dimensional lid-driven cavity flow. Results of two-dimensional and three-dimensional Oldroyd-B liquid jets are then presented. Viscoelastic models are used in applications like food-processing, polymer melt processing, blood flow modeling.

• Simulation of Warm Forming of 5754 Sheet Aluminium

  Trevor Dutton (Dutton Simulation Ltd)

  In November 2009 a project was set up to implement an innovative metal forming process into the automotive industry with the goal of producing lightweight, high accuracy, complex-shaped automotive aluminium panels using one main forming operation. The project was known as WAFT - Warm Aluminium Forming Technology - and was part-funded by the UK Technology Strategy Board. The opening premise was that increased formability could be achieved with existing aluminium grades when heated to temperatures in the range 200°C to 350°C [1]. At these temperatures the material does not undergo re-crystallization or achieve superplasticity yet still exhibits increased formability - but the optimum settings for blank and tool temperatures, and also forming rate, were not known. The project aim was to industrialise the warm forming concept to align with conventional cold processing in order to develop a manufacturing process that could achieve steel formability with aluminium. This was to be confirmed in an industrial cell running a demonstrator tool, at rates optimised for premium vehicle production. The grade of aluminium chosen for the study was 5754; this is widely used for cold forming automotive body-in-white structural panels, and issues regarding assembly and behaviour in the vehicle are well understood. However, the reduced formability of 5754 compared with steel drives body-in-white design to adopt simpler forms and more numerous parts in sub-assemblies to create the required levels of complexity - all of which has significant cost implications and an impact on the overall carbon footprint of the manufacturing process.

• Simulation of Warm Forming of Aluminium 5754 for Automotive Panels

  T. Dutton (Dutton Simulation Ltd), M. Mohamed, J. Lin (Imperial College London)

  The work described in this paper has been carried out as part of a project investigating implementation of an innovative metal forming process into the automotive industry to produce lightweight, high accuracy, complex-shaped automotive Aluminium panel components using one operation. The project, lasting three years, is a collaboration between industrial and academic partners lead by a Premium Automotive Manufacturer with funding from the UK Technology Strategy Board. As part of the objective to not only investigate but also industrialize the technology, finite element simulation methods have been included in the scope of work. This paper will report on the extensive program of material characterization carried out by the academic partner Imperial College London in order to develop and correlate the simulation models. Focus is on the sensitivity of key material properties to both temperature and forming rate, as well as the variation of friction with temperature for various lubricants. The Simulation method has been developed on two fronts. The initial approach takes an existing model and applies it to warm forming processes, chiefly under isothermal conditions; the required input parameters will be discussed. In parallel, a new and more comprehensive user- defined material model incorporating not only thermal and strain rate parameters but also a continuum damage mechanics (CDM) approach has been developed at Imperial College. The capability of the model to predict Forming Limit Curve measurements of 5754 aluminium sheet at various temperatures will be shown. The project is now in its final phase of forming trials using a prototype tool that has been manufactured based on the simulation work to date.

• Simulation of Wave-Dissipating Mechanism on Submerged Structure using Fluid-Structure Coupling Capability in LS-DYNA

  Sunao Tokura, Tetsuji Ida - The Japan Research Institute, Ltd.

  Understanding the wave-dissipating mechanism of seashore structures is important to design effective seashore protection system against high waves. From the engineering point of view, wave dissipation with seashore structures is considered as a kind of fluid-structure interaction (FSI) problem. Recently constructing a submerged structure "flexible mound" is increasing for some advantages. The flexible mound is made of rubbery material and is deformable. Authors tried to apply the ALE (Arbitrary Lagrangian Eulerian) capability in an explicit finite element program LS-DYNA to this problem and compared the behavior of conventional "rigid mound" (breakwater) and flexible mound. Through this preliminary study authors showed that the FSI analysis using LS-DYNA could widely be used to design shore structures.

• Simulation of Wear Processes in LS-DYNA ®

  Thomas Borrvall, Anders Jernberg, Mikael Schill (DYNAmore Nordic AB), Liang Deng, Mats Oldenburg (Luleå University of Technology)

  Wear is an important life-limiting factor of hot forming tools and contributes to the high costs involved in the event of tool replacements and consequential lost production. It is therefore important to understand the complex mechanisms behind wear and to be able to assess the damage it leads to in order to improve tool design. By means of computer simulations and sophisticated wear laws this can be done in a virtual environment, and the aim of this paper is to demonstrate how LS-DYNA in combination with LS-PrePost can be used for this purpose. In version R9 of LS-DYNA, the keyword *CONTACT_ADD_WEAR associates wear laws with contact interfaces and allows for post-processing wear depth on associated surfaces. A goal has been to extend this to a fully-fledged simulation tool for complete wear processes. This includes not only performing a wear simulation, but also using the resulting wear data to modify geometries of interest, and then repeating the procedure for a sufficient number of cycles. It is demonstrated herein that this goal has in principle been reached.

• Simulation of woven composite structures consider-ing manufacturing effects

  Mathieu Vinot, Tolga Usta, Christian Liebold, Martin Holzapfel, Nathalie Toso

  In recent years, advanced material models have emerged in finite-element codes for the simulation of composite materials reproducing realistic failure mechanisms. Through the increased reliability in simulation, less conservative designs of composite structures have been made possible. However, most of the current numerical solutions are considering the composite material independently of real manufacturing conditions, which can strongly affect the local material architecture and properties. To extend the potential of composite structures, it is therefore necessary to enhance the simulation models by including additional information from the production processes. To answer this problematic, many works have focused on the detailed simulation of these processes and on the transfer of information between the simulation steps [1, 2].

• Simulation Technique for Pre-forming of AHSS Edge Stretching

  X. Chen (United States Steel Automotive Center), J. Sun, X. Zhu (LSTC)

  Edge cracking in advanced high strength steels (AHSS) is one of the main failure modes in many sheet metal stamping processes. Pre-forming into a wave (or scallop) shape at the edge is a common technique used to gain material at high edge stretch regions in preparation for the subsequent edge stretch processes. The accurate simulation of this multi-stage forming process remains a challenging task since these edges experience complicated forming processes including bending, unbending, and stretching deformations. In this study, a simulation variable study is performed and the effect of various material models, hardening rules and solvers on the simulation results is also investigated. A simulation technique is established for this multi-stage forming process. Simulation results are compared to experimental data and reasonable agreement is achieved. Different failure criteria are also evaluated and discussed for use in this type of application.

• Simulation-Based Airbag Folding System JFOLD Version 2: New Capabilities and Folding Examples

  Shinya Hayashi (JSOL Corporation), Richard Taylor (Ove Arup & Partners International Limited)

  Computer simulation is playing an increasingly important role in the design, development and application of airbag safety systems. As folding patterns and airbag structures become more and more complex, users are turning to simulation based folding solutions to generate accurately folded models in a short space of time. To meet this demand, a new software tool called JFOLD has been developed by JSOL Corporation to enable successful airbag folding using LS-DYNA®. JFOLD’s intuitive and interactive system guides the user through the folding steps using flow-chart graphics, interactive tool positioning/resizing, tool motion control, animation preview and more. This paper introduces the new capabilities of JFOLD Version 2 and demonstrates various folding examples. JFOLD runs inside the powerful and popular pre-processor Primer.

• Simulations of Axial Impact of Composite Structures with a Coupled Damage-Plasticity Model

  X. Xiao (Michigan State University)

  Under axial impact, a composite structure can split into pieces at the crush front while maintaining an apparent structural integrity in its uncrushed portion. In this way, the structure is capable of sustaining large deformation under a sufficiently high load. To simulate this behavior, the constitutive model must be able to describe the response of a substantially damaged composite under dynamic loading. The constitutive behavior beyond the peak loading is not well represented in common composite constitutive models. This paper presents the recent development of a coupled damage-plasticity model for composites and its applications in crush simulations.

• Simulations of Axially Loaded Straight Aluminium Profiles with Random Geometric Imperfections

  Ø. Fyllingen, O.S. Hopperstad, M. Langseth - Norwegian University of Science and Technology

  Stochastic simulations of square aluminium tubes of 6060 T6 aluminium alloy subjected to axial crushing have been performed in LS-DYNA and compared to existing experiments. The main variables of the experimental study were the extrusion length, the wall thickness and the impact velocity. Three different buckling modes were observed; progressive buckling, a transition from progressive to global buckling and global buckling. In the present study it has been investigated if it is likely that geometric imperfections modelled by assumed Gaussian random fields can explain the experimentally observed behavior. Variation of the random field parameters by use of a factorial design resulted in variations in especially the buckling modes and consequently the average force.

• SIMULATIONS OF HYPERVELOCITY IMPACTS WITH SMOOTHED PARTICLE HYDRODYNAMICS

  Dominique Lacerda, Jean-Luc Lacome - DYNALIS, France

  This paper is devoted to the results of Smoothed Particle Hydrodynamics (SPH) simulations of high velocity impacts on thin aluminium plates using LS-DYNA computer code. The numerical results of the damage produced on plates are compared with experimental data. Two simulations are presented : - An aluminium sphere impacting an aluminium plate at 6.64 km/s - A steel sphere impacting an aluminium plate at 5.53 km/s Experimental and numerical results are in good agreement.

• Simultaneous Exploration of Geometric Features and Performance in Design Optimization

  Nivesh Dommaraju (Technical University of Munich), Mariusz Bujny, Stefan Menzel, Markus Olhofer (Honda Research Institute Europe GmbH), Fabian Duddeck(Technical University of Munich / Queen Mary University of London)

  Topology optimization (TO) algorithms generate novel concepts to inspire and propel the design iteration process. LS-TaSC® is an industrial tool that implements TO algorithms and generates designs optimized for performance objectives such as maximum stiffness or energy absorption, under specified constraints e.g. allowed mass fraction of material in the design space. A multi-objective design exploration framework based on LS-OPT® and LS-TaSC to generate designs is already available. The framework yields a Pareto set of designs by varying a parameter representing the relative preference of the user among the different objectives. A challenge persists as to how potentially large datasets of designs, generated using such an approach, can be reviewed efficiently by a designer. In this paper, we propose a method to identify a few representative design prototypes, which can be more easily reviewed by a designer. More concretely, the approach identifies classes of designs that look significantly different from a geometric point of view. For this purpose, we encode the information about the geometry using a voxel representation of the design. Subsequently, we use Principal Component Analysis (PCA), to reduce the high dimensionality of the representation, and extract features that encapsulate the geometric variation in the set of designs. Design prototypes are derived based on clustering algorithms using weights of principal components as features. To evaluate the proposed approach, we consider a solid beam model that is optimized for high stiffness under a static load case and high-energy absorption in a crash load case. Similar design problems are especially common in the car body design. We generate a Pareto set of designs for this test case and identify design prototypes. An interesting application of this method is to find designs with similar geometric appearance but very different performances. This can help us to estimate the robustness of a design. By helping in design exploration and selection, the proposed approach shows promise in large-scale industrial applications.

• SimWeld and DynaWeld Software tools to setup simulation models for the analysis of welded structures with LS-DYNA

  Tobias Loose (Ingenieurbüro Tobias Loose), Oleg Mokrov (ISF Aachen)

  The analysis of residual stresses or distortion of welded structures requires a welding structure analysis. This kind of analysis incorporates some specifics compared to other FEM-simulations. Apart from the definition of geometry (mesh) and clamps, the welding structure analysis requires the definition of heat sources, trajectories and time schedules. The heat source applies the heat in the model according to the welding process. An equivalent heat source is used which needs to be calibrated for tests or predictively calculated from a welding process analysis. The trajectories describe the path of the moving welding heat source in the simulation model. Most welding heat sources are not rotational symmetric. Their trajectories require a path to define the local origin of the heat sources and a reference line to define the orientation of the heat source. Welding is a transient process where the time schedule of the actions - welding time, intermediate time - has an impact on the result. The process plan defines the welding time schedule and has to be considered in the simulation model.

• Sled Tests and Simulation Results with Q10 Update Kit Euro NCAP 2020

  H. Ipek (Daimler)

• Sloshing response of a LNG storage tank subjected to seismic loading

  Rosario Dotoli, Daniela Lisi, Danilo Bardaro - CETMA, Marco Perillo, Massimo Tomasi - EnginSoft

  The number of Liquefied Natural Gas tanks is continually increasing. These tanks are very large and their capacity is about 150000[m3]. According to safety standards these kinds of tanks consist of an inner steel shell, containing the LNG, and an outer reinforced concrete shell. Nevertheless, they represent a great risk if they fail during an earthquake. Several types of tank failures have been observed. Tanks may be damaged for different reasons. Large shell hoop tensile stresses, resulting from a combination of hydrostatic pressure and hydrodynamic pressure, due to horizontal and vertical ground motions, could fail the tank. A more common type of failure is known as “elephant’s foot buckling”[3]. This is caused by the large overturning base moments, resulting from the impulsive and convective liquid loading on the tank wall during an earthquake. The high vertical compressive stresses, which develop in the tank wall, may cause the buckling of the structure. The aim of this work is to simulate the seismic behaviour of an LNG tank during an earthquake. The analyses have been performed with Ls-Dyna code using a Lagrangian Conference approach [1],[5]. The applied seismic loads have been registered during a Richter magnitude 7.1 earthquake (Magnitude Moment 6.9). Simulations have shown that fluid motion and fluid-structure interaction are responsible of a failure type known as “elephant’s foot”. 3-D results of the large model (76 [m] in diameter) have been visualized with the support of a multi-wall screen at CETMA Virtual Reality Centre (CVRC). This BARCO visualization system is based on ORAD pc cluster with Digital Video Graphics DVG-10, with tracking and stereo capabilities. The FEM model consists of a flat anchored bottom and a cylindrical metallic wall in contact with the LNG: Diameter Wall high Liquid level Liquid volume Tank mass Liquid mass 76[m] 41[m] 38[m] 172000[m3] 4470[ton] 68954[ton]

• Small Electric Car Front Cross-Member Assembly Low Speed Impact Simulation

  Prof. G. Lampeas; I. Diamantakos, K. Fotopoulos (University of Patras); I. Benito (Batz S.);

  In the frame of EVolution project a small electric car has been developed. One of the demonstrators of car structure design is the front cross-member assembly. In the present work the numerical simulation of the front cross-member assembly low speed impact is presented. The crash is considered according to Allianz test protocol. The basic features of the front cross-member assembly structure comprise the application of foam type materials (more specifically low density poly-urethane foams) and crash boxes design, which are assembled behind the transversal beam; both features aim at the maximum possible impact energy absorption during a crash event. FE models of all assembly parts are built and the FE model of the whole front cross-member assembly is constructed applying proper contact definitions and initial conditions. The developed FE model is solved using LS-DYNA explicit FE code. Strain-rate depended material properties are utilized for the foam materials. Numerical simulation results concerning structural deformations, absorbed kinetic energy and force applied on the vehicle during impact evolution are drawn and presented. For the validation of the numerical model a physical test according to Allianz test protocol has been performed. Numerical simulation results compare well with experimental test measurements, leading to successful validation of the developed FE model.

• Small-overlap Crash Simulation Challenges and Solutions

  S. R. M. Arepalli, G. Kini, A. Gittens (ESI Group)

• Smart Manufacturing: CAE as a Service, in the Cloud

  W. Gentzsch (The UberCloud)

  The benefits for small and medium size businesses (SMBs) and research departments of using High Performance Technical Computing (HPTC) within their design and development processes can be huge. For example enormous cost savings; reducing product failure during design, development, and production; develop optimized processes; achieve higher quality products; and shorten the time to market or scientific result. Potentially, all this can lead to increased competitiveness, deeper insight, and more innovation. However, the vast majority of SMBs perform virtual prototyping or large-scale data modeling still on their desktop computers.

• SMILE – Alternative Input Language for LS-DYNA (and Other Solvers)

  B. Näser (BMW Group), D. Friedemann, J. Rademann (HTW Berlin)

  To ensure today’s development cycles for products and components, the main part of the development process has to be supported by numerical simulations. For complex parts, many simulation disciplines have to be considered to meet all the requirements. This results in a usage of different simulation tools with different input file languages. Moreover, a typical simulation engineer has to be an expert for numerical simulation (in most cases for a specific solver), and also an experienced engineer (for a specific development discipline).

• Smooth Particle Hydrodynamics (SPH): A New Feature in LS-DYNA

  Jean Luc LACOME - DYNALIS

  A new particle element has been added to LS-DYNA. It is based on Smoothed Particle Hydrodynamics theory. SPH is a meshless lagrangian numerical technique used to model the fluid equations of motion. SPH has proved to be useful in certain class of problems where large mesh distortions occur such as high velocity impact, crash simulations or compressible fluid dynamics. First, we introduce the basis principles of the SPH method. Then the coupling of this technique to LS-DYNA is presented and the input needed for such analysis is provided.

• Smoothed Particle Galerkin Method with a Momentum-Consistent Smoothing Algorithm for Coupled Thermal-Structural Analysis

  X. Pan, C.T. Wu, W. Hu, Y.C. Wu, Livermore Software Technology Corporation

  This paper introduces a momentum-consistent smoothing algorithm to Smoothed Particle Galerkin (SPG) method [1] in LS-DYNA® for the coupled thermal-structural analysis. In contrast to the kernel approximation in conventional Lagrangian particle methods, the system of equations of the present method is discretized and approximated following that in the SPG method. The momentum-consistently smoothing algorithm provides the desired stability and accuracy in the thermal structural coupling applications. Furthermore, the algorithm is coupled with FEM with sharing nodes to increase the computational efficiency. Two benchmarks including heat flux and thermal expansion are studied to demonstrate the accuracy of the present method. In addition, the frictional drilling test is simulated to demonstrate the effectiveness of the proposed method in the coupled thermal-structural analysis involving material failure.

• Smoothed Particle Hydrodynamics Modeling of Granular Column Collapse

  Y. Li, N. Zhang, R. Fuentes (RWTH Aachen)

  Granular column collapse is a commonly studied granular flow problem, where an initially cylindrical column of dry granular materials collapses onto a flat surface under gravity. In this study, the meshless method Smoothed Particle Hydrodynamics (SPH) is used to model this phenomenon examining in particular the effect of aspect ratio, defined as the ratio of the initial height h0 and radius r0 of granular column. The numerical results are consistent with experimental results in terms of three aspects: (1) description of flow shapes; (2) runout distance and (3) final deposit height. Further observations and measurements are obtained to explore the collapse.

• Soft Soil Impact Testing and Simulation of Aerospace Structures

  Edwin L. Fasanella, Karen E. Jackson, Sotiris Kellas - NASA Langley Research Center, VA

  In June 2007, a 38-ft/s vertical drop test of a 5-ft-diameter, 5-ft-long composite fuselage section that was retrofitted with a novel composite honeycomb Deployable Energy Absorber (DEA) was conducted onto unpacked sand. This test was one of a series of tests to evaluate the multi-terrain capabilities of the DEA and to generate test data for model validation. During the test, the DEA crushed approximately 6-in. and left craters in the sand of depths ranging from 7.5- to 9-in. A finite element model of the fuselage section with DEA was developed for execution in LS-DYNA®, a commercial nonlinear explicit transient dynamic code. Pre-test predictions were generated in which the sand was represented initially as a crushable foam material MAT_CRUSHABLE_FOAM (Mat 63). Following the drop test, a series of hemispherical penetrometer tests were conducted to assist in soil characterization. The penetrometer weighed 20-lb and was instrumented with a tri-axial accelerometer. Drop tests were performed at 16- ft/s and crater depths were measured. The penetrometer drop tests were simulated as a means for developing a more representative soil model based on a soil and foam material definition MAT_SOIL_AND FOAM (Mat 5) in LS- DYNA. The model of the fuselage with DEA was re-executed using the updated soil model and test-analysis correlations are presented.

• Software for Creating LS-DYNA® Material Model Parameters from Test Data

  Eric Strong, Hubert Lobo (Matereality), Brian Croop (DatapointLabs)

  LS-DYNA contains a wealth of material models that allow for the simulation of transient phenomena. CAE Modeler is a generalized pre-processor software used to convert material property data into material parameters for different material models used in CAE. In a continuation of previously presented work, we discuss the extension of the CAE Modeler software to commonly used material models beyond MAT_024. Software enhancements include advanced point picking to perform extrapolations beyond the tested data, as well as the ability to fine-tune the material models while scrutinizing the trends shown in the underlying raw data. Advanced modeling features include the ability to tune the rate dependency, as well as the initial response. Additional material models that are quite complex and difficult to calibrate are supported, including those for hyperelastic and viscoelastic behavior. As before, the written material cards are directly readable into the LS-DYNA software, but now these can also be stored and cataloged in a material card library for later reuse.

• Soil Modeling for Mine Blast Simulation

  Frank Marrs, Mike Heiges (Georgia Tech Research Institute)

  This paper presents the results of an effort to correlate an LS-DYNA® simulation of a buried mine blast with published experimental test data. The focus of the study was on simulating the effects of soil moisture content on the blast characteristics. A mathematical model for sand is presented that is based on several previously proposed models. The simulation correlates well with the results of a mine blast experiment, thus validating the material model for sand at varying levels of saturation. The model provides an excellent baseline for blast simulations of buried mines and a soil material model that can be expanded to include higher fidelity modeling, different soil types, and real-world applications.)

• Solid Elements with Rotational Degree of Freedom for Grand Rotation Problems in LS-DYNA

  Hailong Teng - Livermore Software Technology Corporation

  The goal of this paper is to further enhance the solid elements with rotational degree of freedom (DOF). Three- dimensional finite elements with rotational degree of freedom have been proposed elsewhere, however, these elements are restricted to linear analysis. In this paper, by improving the mid-side node velocity update algorithm, we enhance the elements performance. Numerical results are presented, showing that the enhanced elements are capable of dealing with grand rotation problem. The enhanced formulation has been implemented into LS-DYNA® for solid element 3 and solid element 4.

• Solution Explorer in LS-PrePost – a GUI for Nonlinear Implicit FE

  T. Borrvall (DYNAmore Nordic)

  The evolvement of multiphysics capabilities in LS-DYNA has made it a very powerful, albeit somewhat complicated, simulation product. To this end, the Solution Explorer was introduced to simplify modeling setup in fluid mechanics, and this has now been complemented with a framework for nonlinear implicit mechanics. The vision of the Solution Explorer is to combine simplicity and power in an integrated pre- and post-environment, and this workshop presents its current state. We cover pre- and post-processing for single and multiple cases, in hope that it will provide a clear picture of its future potential.

• Solving of Crash Problems of the Fuel Supply Modules in the Fuel Tank

  M. Dobeš, J. Navratil (Robert Bosch)

  This article in the first part deals with the experimental measurement of the material data used for explicit computational FEM analyses. The second part of this paper devotes practical application of the FEM simulation in fuel tank domain and fuel supply modules (FSM). The main focus is on the material computational models, especially material models with strain rate dependence. These computational models are used for polymer materials, like TSCP (Typical Semi-Crystal Polymer).

• SOME APPLICATIONS OF LS-OPT TO BIRD IMPACT SIMULATION

  Peter Starke, Leonhard Mitterleitner - EADS Military Air Systems

  This paper describes the application of LS – OPT for assessment of the influence of stochastic effects in bird strike events. To address the problem, a two – step approach has been chosen. In the first step, LS – OPT has been used in order to automatically determine the penetration velocities for different impact sites. In a second step, LS – OPT was used to create a response surface from the calculated penetration velocities. Subsequently, for a given scatter in the impact site the resultant statistical distribution has been determined by LS – OPT.

• SOME EXAMPLES OF ENERGETIC MATERIAL MODELLING WITH LSDYNA

  Michel QUIDOT -SNPE Propulsion – Centre de Recherches du Bouchet

  SNPE is using DYNA codes for more 15 years for characterisation and modelling of energetic materials : high explosives, solid propellants, gun propellants and pyrotechnic systems for functioning, safety, survivability and vulnerability analysis in space and defence applications. This paper presents some examples of the use of LSDYNA in the field of solid mechanics, fluid mechanics and detonics. The first example concerns the development of a constitutive model for a cast PBX. A general dynamic viscoelastic model developed in LSDYNA is used to analyse Split Hopkinson Pressure Bar (adapted for soft materials characterisation) experiments, reverse Taylor test instrumented by high speed framing camera and VISAR system. A postprocessing variable implemented is used for analysing dynamic failure in dynamic Brazilian tests performed with SHPB system. Two others short examples are given : functioning of a pyrotechnic system separation in space application and LSDYNA/Euler simulation of the interaction of blast waves with explosive charges in sympathetic detonation phenomena.

• Some New Features of the Dual CESE solver in LS-DYNA and its applications

  Grant Cook Jr, Zeng-Chan Zhang

  In this paper, we briefly review the dual-CESE solver that is an improved version of the regular CESE solver. For instance, compared to the regular CESE solver, it is more accurate and stable, and particularly more stable for triangle (2D) /tetrahedral (3D) meshes, all while maintaining the core features of the CESE method. Some of the new features of the Dual CESE solver in the R15 release will then be explained.

• Some observations on failure prediction in sheet metal forming

  Mats Larsson - Saab Automobile, Sweden, Kjell Mattiasson - Chalmers Univ. of Technology, Sweden, Mats Sigvant -Volvo Cars Manuf. Engng., Sweden

  This paper presents results from a FE-study on failure prediction in ductile metal sheets. The studied material, a DP600 dual phase steel, is used throughout the study. The effects of variation of element sizes, material parameters, and friction are shown and discussed. Also results from simulations of in-plane and out-of-plane tests are compared and discussed.

• Sonic weld characterization and FEA modeling method development for automotive applications

  ABM Iftekharul Islam, Salvador Beltran Ruelas, Lisa Koch, Onkar Akolkar

  Joining is a critical part of any structure for transferring load and maintaining integrity for the product. Ultrasonic weld is one of the popular methods for joining plastic parts in automotive industry. Along with providing a visually demanding finish, the method has been established for tight, strong, and dimensionally accurate joints. With the increase of complexity and integration of electrical and sensing instrumentation in autonomous and electric vehicles, sonic weld provides a necessary means of attaching plastic parts without compromising visual impact. However, the sonic weld performance is yet to be quantified, and the criteria for capturing weld separation, and losing this connected load path during structural vehicle analysis, has not been studied extensively. Sonic welds, even though it is a very effective joining method, the whole tooling process is expensive and time consuming. Ideally, to optimize the welding spot number and develop future cost-effective welding methods, it is crucial to understand the actual weld performance under several variables such as material type, temperature, strain rates, etc.

• Sound Absorbing Porous Material in Statistical Energy Analysis

  Zhe Cui, Yun Huang, LSTC Livermore California USA;, Mhamed Souli, Lille University France;, Tayeb Zeguar, Jaguar Land Rover UK

  For high frequency analysis, Statistical energy analysis (SEA) has proved to be a promising approach to the calculation of sound transmission in complex structures. In automotive industry and also in civil engineering, most of noise transmission is due to high-frequency structural vibrations, where the characteristic wavelength is small compared to the dimensions of the structure. For these applications classical methods of structural analysis, such as the finite element method (FEM), and Boundary Elements Method (BEM), cannot be used due to the large number of degrees of freedom required to model structural deformation. Statistical Energy Analysis (SEA) considers the vibrations of the structure in terms of elastic waves which propagate through the structure and are partially reflected and partially transmitted at structural connections. For the last few years, there has been an increase in the application of SEA techniques to study noise transmission in motor vehicles.

• Sound Radiation Analysis of a Tire with LS-DYNA

  Zhe Cui, Yun Huang (LSTC)

• Spectral Element Methods for Transient Acoustics in ANSYS LS-DYNA®

  T. Littlewood, Y. Huang, Z. Cui (Ansys/LST)

  Increasingly there is an emphasis in the engineering simulation community on ultrasonic devices. They are seen in medical imaging, structural health monitoring, and of course, in the rapidly emerging world of autonomous/semi-autonomous vehicles. These devices operate at frequencies of 50KHz and above, sometimes well above. Wavelengths at those frequencies are measured in millimeters, sometimes even micrometers. The simulation of the propagation of such short waves over any substantial distance is a very demanding endeavor. This is especially true if tri-linear/quadratic iso-parametric finite elements are used. Newer, higher-order finite element methods exist [1]. Among those methods is the spectral element method (SEM). Many SEM references are available in the literature, a sampling being [1-6.] Spectral elements are appealing because they are highly accurate and can be efficiently incorporated in an explicit solver like LS-DYNA. In a massively parallel setting, they allow for the solution of models with billions of degrees-of-freedom in a reasonable amount of time.

• Speeding Up LS-DYNA Implicit with Mixed Precision, Low Rank Approximations, and Accelerators

  Cleve Ashcraft, Jason Cong, Florent Lopez, Roger Grimes, Robert Lucas, Francois-Henry Rouet, Linghao Song

  The multifrontal method of Duff and Reid [1] dominates the runtime of most LS-DYNA im-plicit analyses. Its complexity will range from O(N1.5) to O(N2), depending on the model. This paper will give an overview of attempts to reduce the run time of solving large systems of linear equations, both on the host processor as well as with accelerators. Most of what is discussed herein is available today in the development version of LS-DYNA and should be released with R15. Everything discussed herein only applies to our symmetric indefinite solver.

• Speeding up the Pedestrian Protection CAE Process

  G. Newlands, C. Archer (Arup)

  Pedestrian protection is increasingly important to the design and development of the front end of vehicles. The various protocols, impactors and methods relating to pedestrian protection mean that the CAE process can be complex and time consuming. Arup has developed various tools to aid in this process which are used internally within Arup when working on automotive consultancy projects as well as being available externally in the Oasys LS-DYNA® environment software. These tools are available for both head and leg impact analyses. This paper describes the tools and also how they have been used on real world projects.

• SPH Coupled Simulation for Blast and Impact study on Reinforced Concrete Bunker buried under Soil

  Priya Gautam, Hrishkesh Sharma

  This study examines how concrete structures respond to extreme conditions, particularly coupled simulation for blast and impact analysis, using LS-DYNA software for simulations. By analyzing displacement, pressure, strain, and stress, we aim to understand failure mechanisms and quantify damage in buried bunkers, providing insights for structural design and resilience assessments. In addition, coupled simulation for blast impact analysis, we consider durability and survivability under extreme conditions. This includes assessing long-term structural integrity, understanding environmental effects on material properties, and ensuring structures can function effectively after extreme events.

• SPH Formulations: New Developments in LS-DYNA

  J. L. Lacome - Livermore Software Technology Corp

  “Standard” SPH methods are based on an Eulerian kernel. In most cases, the support remains constant and the neighbors search is carried out at each time step. This allows to deal with large deformation problems. However, this technique may suffer from instabilities (such as the so-called tensile instability [Xiao 05]). In the case of a Lagrangian kernel, the neighbors’ list remains constant throughout the calculation. This formulation overpasses the tensile instability problems but the treatment of large deformations becomes limited [Xiao 05]. In order to solve this problem, Vidal et al. [Vidal 07] proposed a very interesting approach based on a formulation with updated Lagrangian kernel. They showed that the reference state update and the neighbor list update allow large deformations modeling. Nevertheless, when this reference state is too frequently actualized, numerical instabilities can appear. Recent developments based on Eulerian and Lagrangian kernel SPH coupling have been introduced in lS-DYNA version 971. First, we present a coupling between Lagrangian kernel particles and Eulerian kernel particles. Then, an impact of a rigid projectile on a composite material modeled with a lagrangian kernel is showed in order to visualize the advantages of this new element technology.

• SPH Formulations: New Developments in LS-DYNA

  J. L. Lacome - Livermore Software Technology Corp

  “Standard” SPH methods are based on an Eulerian kernel. In most cases, the support remains constant and the neighbors search is carried out at each time step. This allows to deal with large deformation problems. However, this technique may suffer from instabilities (such as the so-called tensile instability [Xiao 05]). In the case of a Lagrangian kernel, the neighbors’ list remains constant throughout the calculation. This formulation overpasses the tensile instability problems but the treatment of large deformations becomes limited [Xiao 05]. In order to solve this problem, Vidal et al. [Vidal 07] proposed a very interesting approach based on a formulation with updated Lagrangian kernel. They showed that the reference state update and the neighbor list update allow large deformations modeling. Nevertheless, when this reference state is too frequently actualized, numerical instabilities can appear. Recent developments based on Eulerian and Lagrangian kernel SPH coupling have been introduced in lS-DYNA version 971. First, we present a coupling between Lagrangian kernel particles and Eulerian kernel particles. Then, an impact of a rigid projectile on a composite material modeled with a lagrangian kernel is showed in order to visualize the advantages of this new element technology.

• SPH Modeling of Cutting Forces while Turning of Ti6Al4V Alloy

  A. A. Olleak, H. El-Hofy (Egypt-Japan University of Science and Technology)

  A growing interest in modelling and simulation of machining processes has been witnessed in the past few decades. Smoothed particles hydrodynamics (SPH), one of the latest and developing methods used for that purpose, is a powerful technique that can be efficient in handling problems in which large deformation occurs. This technique is able to overcome the shortcomings of the traditional finite element methods. One of these shortcomings is the need to adopting a damage model that artificially initiates the crack, and therefore, the accuracy will be affected.

• SPH Performance Enhancement in LS-DYNA

  Gregg Skinner, Dennis Lam - Advanced Technical Computing Center, Masataka Koishi - Yokohama Rubber Corporation, Hiroki Shimamoto - NEC Corporation

  The Smoothed Particle Hydrodynamic (SPH) method had been implemented in LS-DYNA for some time. However, SPH had not been used extensively; therefore, performance issues were never highlighted and never addressed. Recent efforts to run SPH on NEC SX systems revealed substantial performance problems. NEC, Yokohama Rubber Corporation and LSTC collaborated to enhance the performance of SPH. As a result, the performance of SPH function in LS-DYNA has been improved on NEC SX-6 vector-parallel supercomputer by a factor of four. This article provides some background information about the code tuning effort, the SX series vector-parallel supercomputers, and the performance improvement achieved

• SPH Simulations of High Velocity Impacts on Concrete Plate

  Dr. Tatsuo Sakakibara, Dr. Toru Tsuda and Ryo Ohtagaki - ITOCHU Techno-Solutions Corporation

  The local damages of the concrete plate are produced by high velocity impact of rigid projectile. In order to represent the cracking or perforation behaviours of the concrete, SPH is appropriate method because of completely mesh free. In this paper, SPH simulations for the local damage of the concrete plate due to high velocity impacts are performed to study the effects of the impact velocity and the strength of the concrete plate. To represent the nonlinear failure behaviour of concrete, MAT_PSEUDO_TENSOR is used as constitutive model in LS-DYNA. The strain rate effects of concrete are also take into account. The numerical results of the local damage of concrete plates are discussed through comparing with experimental results.

• SPH Simulations of High Velocity Impacts on Concrete Plate

  Dr. Tatsuo Sakakibara, Dr. Toru Tsuda and Ryo Ohtagaki - ITOCHU Techno-Solutions Corporation

  The local damages of the concrete plate are produced by high velocity impact of rigid projectile. In order to represent the cracking or perforation behaviours of the concrete, SPH is appropriate method because of completely mesh free. In this paper, SPH simulations for the local damage of the concrete plate due to high velocity impacts are performed to study the effects of the impact velocity and the strength of the concrete plate. To represent the nonlinear failure behaviour of concrete, MAT_PSEUDO_TENSOR is used as constitutive model in LS-DYNA. The strain rate effects of concrete are also take into account. The numerical results of the local damage of concrete plates are discussed through comparing with experimental results.

• Spotweld Failure Prediction using Solid Element Assemblies

  Skye Malcolm - Honda R&D Americas Inc., Emily Nutwell - Altair Engineering

  One current methodology for spotweld modelling utilizes a tied contact to connect the weld elements to the components. In order for this contact to be robust and acceptably mesh independent, multiple solid elements are needed to represent a single weld. Several studies were conducted which concluded that a cluster of eight hex elements provides significantly improved performance over a single beam or hex element. However, ease of use is critical to the application of these spotwelds since thousands of welds can be present in a single full vehicle model. Therefore, a single output is generated for each weld assembly rather than on an element basis. The time step for these hex clusters is controlled by the smallest edge length so using multiple elements does not result in a time step penalty since the thickness of the weld is usually the smallest edge length. This paper will present the development of the eight hex cluster weld, followed by the validation process of these cluster spotwelds. Failure parameters for the resultant-based Mat 100 Damage-Failure model were derived by simulating coupon tests of single welds in shear and tension failure. These failure parameters were then used in a component test model with dozens of welds, several of which failed under the applied load. Finally, these parameters were applied to a full vehicle model using automatic sorting of the welds by the pre-processing software. At both the component and full vehicle level, good agreement was found between simulation and test results. The additional mass scaling and run time penalties of the cluster spotwelds were not significant. Furthermore, the effort needed to apply automatic methods to organize the welds is small enough to be practical in the production CAE environment.

• Spotweld Modeling Methodologies and Failure Characterization of Aluminum Resistance Spotwelds (RSW) using LS-DYNA

  Akshay Kulkarni, Ashwin Yeagappan, Joao Moraes, Lily Slabbert, Martin Vézina

  With an increased use of aluminum in automotive body structures, developing a deep understanding, and capability to model failure of aluminum resistance spotwelds (RSWs) is critical [1]. This paper discusses failure card development of aluminum RSWs using LS-DYNA for certain 5000 and 6000 series flat rolled sheet alloys used in automotive structural applications.

• Springback Analysis and Optimization in Sheet Metal Forming

  Abdulaziz Alghtani, P.C. Brooks, D.C. Barton, V.V. Toropov (School of Mechanical Engineering University of Leed)

  An accurate prediction of springback in sheet metal forming processes requires complex hardening material models. In this research, numerical analysis of the springback in U-bending was conducted using the well-known Yoshida model, available and known as the YU model in LS-DYNA. This model has seven main parameters which describe the behaviour of the material as it undergoes metal forming processes. Initially, mesh sensitivity studies were conducted to derive a suitable mesh that represents an appropriate compromise between accuracy and computer time. Secondly design of experiment (DoE) was employed to make 30 combinations of two design variables (die radius and clearance) uniformly through a design space. Parametric optimisation studies were also conducted to investigate the influence of these variables and to make recommendations to minimise the springback. The results show that the blank element mesh density has a significant effect on the springback prediction. Additionally the results demonstrate that certain geometrical parameters have a significant impact in controlling the springback but that optimised values can be identified to minimise the effect.

• Springback analysis in Andvanced High Strength Steel using a new flexible semi-industrial tool geometry, the flex-rail

  A. Andersson - Volvo Cars Body Components, Sweden

  The automotive industry is using more and more of Advanced High Strength Steel in order to reduce the weight of the car. Since this will generate more springback, it is of vital importance to be able to predict the amount of springback in the parts. Otherwise, many late changes have to be made in order to fit the parts in their position. In order to increase the ability to understand and test the behavior of the springback in sheet-metal parts, a new semi-industrial experimental tool, the flex-rail, has been developed. This is a very flexible tool, which can be used for various kinds of materials, from mild steel and aluminum to advanced high strength steel such as TRIP-steel and CP-steel by using different inserts. The tool is designed for experimental analysis of 3D-springback, which is the case in the more complicated automotive parts, such as bpillars and side members. The scope of this work is to analyze the springback behavior and prediction for Advanced High Strength Steel both numerically and experimentally. Sheet-metal-forming simulations were made in LS-DYNA. The results proved that the new geometry, flex-rail, gave a complex springback behavior for all tested materials. Furthermore, the prediction of springback showed good correlation in sections with small amounts of twist but that LS-DYNA underpredicts the springback for sections with large amounts of twist for all materials.

• Springback Calculation of Automotive Sheet Metal Sub-assemblies

  Volker Steininger, Xinhai Zhu, Q. Yan, Philip Ho (Tiwa Quest AG, LSTC)

  In recent years the spring back calculation of a sheet metal part after forming has achieved a high accuracy. Today we are able to calculate the spring back amount after all forming operations of the part including trimming, piercing and reforming. But the spring back of a single sheet metal part is only the first step to solve the problem. What matters at the end is the spring back of the assembly or the sub-assembly of multiple sheet metal parts. This paper describes a GUI for an efficient setup of a spring back calculation of multiple sheet metal parts, taken into account the complete forming history of the parts. It will be shown how to position the sheet metal parts, how to define an assembly sequence and joining method and the hemming process of outer and inner panels and how to launch the LS-DYNA® simulation.

• Springback in Assembly of Mirror Panels with Stamped Supports for Concentrating Solar Power Applications

  J. Pottas, J. Coventry (The Australian National University)

  Solar collector fields consisting of a large number of heliostats are used to reflect and concentrate sunlight onto a tower receiver (Figure 1a) in concentrating solar power (CSP) plants. In the most common tower CSP configuration, shown in Figure 1b, the concentrated light is used to heat a recirculating molten salt heat transfer fluid. A portion of this flow is used to generate steam immediately to drive a Rankine power cycle, while the remainder is stored in insulated tanks to enable 24 hour dispatchable power generation.

• Springback in High Strength Anisotropic Steel

  Oladipo Onipede, Carlos J. Gomes - University of Pittsburgh

  This paper presents the finite element analysis and results of springback in a U-shape cross section made of high strength anisotropic steel. The results are compared with those obtained from two isotropic materials that have the same yield stresses as those of the principal directions of the anisotropic steel sheet. The principal directions are the directions of the sheet that have the largest and smallest yield stresses respectively. The results show the discrepancy between springback predicted by the isotropic and anisotropic materials, but also the variability of springback with respect to the angle of orientation of the anisotropic steel sheet. This may help address the question of when it is appropriate to use isotropic material properties for anisotropic materials when it comes to predicting springback.

• Springback Simulation of the Numisheet 2005 Benchmark II Using DP600

  Tim Lim, Tim Dietrich - Dofasco Inc, Canada

  This study uses a design of experiments (DOE) methodology to investigate the sensitivity of springback prediction to various numerical parameter for the Numisheet 2005 cross member (Benchmark II). The parameters investigated are; through thickness integration points (21 Gaussian integration points through the thickness vs. 7), using a static implicit finish in the forming simulation, element size (number of adaptive levels), and coulomb friction. The average effect of these parameters on the resulting springback was then quantified. Overall, it was found that element size and friction have the greatest effect on the predicted springback and that little is gained by using an implicit finish and 21 integration points through the thickness. Possible reasons for this are discussed and it is then stressed that, these results cannot be generally applied to all situations. In other words, the results point to the possibility that some parts (such as this one) are not sensitive to increasing integration points (from 7 to 21) or an implicit finish. It was also found that despite all combinations of numerical parameters, the wall curl on one side of section I of the Benchmark could not be reproduced

• Stability of THUMS Pedestrian Model and its Initial Trauma Response Against a Real-Life Accident

  L. Wen, C. Bastien, M. Blundell, C. Neal-Surgess (Coventry University), K. Kayvantash (CADLM)

  With dramatically rapid development of computing and modelling technology, occupant and pedestrian safety models went through the development of crash test dummies and multi-body mathematical dynamic modelling to finite element pedestrian human model (THUMS 4.0). THUMS 4.0 is a state of art human model which includes a skeleton structure, as well as internal organs and soft tissues, which makes it a suitable candidate to analyse accident trauma.

• Stabilized DSG Elements – A New Paradigm in Finite Element Technology

  Manfred Bischoff, Frank Koschnick, Kai-Uwe Bletzinger - Technische Universität München

  The Discrete Shear Gap Method, initially proposed for the elimination of transverse shear locking in plate and shell finite elements is extended to a more general concept, applicable to other locking problems, typically causing severe trouble in structural analysis, especially in the case of thin-walled structures. The outstanding feature of the proposed formulation is the fact that one unique method is used to avoid various different kinds of locking phenomena. It is applicable to beam plate and shell elements, but also to two-dimensional and three-dimensional solid elements. The fact that approximation quality is often subject to strong sensitivity to mesh distortion can be alleviated with the help of stabilization methods.

• Stacked Shell Modeling for Evaluation of Composite Delamination in Full Vehicle Simulations

  Olaf Hartmann (ARRK Engineering)

  Accurate prediction of delamination in composite materials is a challenge and often limits the application of lightweight materials in safety relevant components, as it may reduce the available strength significantly. Very detailed modeling (e.g. with solid elements) can be employed to correctly recreate this phenomenon, but this can normally not be simulated in a full vehicle simulation in an acceptable amount of time. Single shell modeling is widely used in full vehicle simulations because of its high runtime performance but cannot support the physical separation of layers. In order to correctly evaluate delamination of composites while retaining a good runtime performance, a new modeling approach in LS-DYNA® was studied in this paper. A stacked shell modeling technique was developed. The new modeling approach was firstly investigated at coupon level with comparison with experimental results for assessing its accuracy and capability of delamination prediction. Furthermore, stacked shell modeling was adopted into components under more complex loading and its performance was evaluated in terms of accuracy and run time compared with conventional modeling. At the end, this modeling technique was studied in full-vehicle simulation. Our stacked shell modeling approach has shown promising results at coupon and component level. At the full-vehicle simulation scale, the new modeling approach has presented robust delamination prediction capability while still retaining high run time performance. The approach presented in this paper can be adopted in full-vehicle crash and also aerospace simulations in order to evaluate composite delamination.

• Staged Construction of an API 650 Tank on a Settling Foundation

  Alexander Hay, Rudy du Preez, Roelof Minnaar (Advanced Structural Mechanics (Pty) Ltd)

  The staged construction of an API 650 tank is analyzed in this paper. The tank is considered to be erected on a foundation that is initially irregular, and which then experiences differential settlement during the course of construction. The consequence of foundation settlement and initial irregularity is that the final shape of the tank deviates from the intended cylindrical shape. During construction, each strake is added to the tank by positioning the (relatively flexible) rolled plate segments on the top edge of the strake below, while at the same time maintaining a fixed gap between vertical edges of adjacent plates. Once positioned, the vertical welds between plates are executed, and then the circumferential weld to the strake below. As such, the strakes can be considered to be placed on top of each other in a deformed (as dictated by the shape of the top edge of the strake below), but essentially stress-free manner. The structural response of the tank as a whole is also affected by a wind girder, which is moved up the tank in a sequence of temporary positions as the strakes are added, until it is fixed in its final position to the top strake of the tank. In its sequence of temporary locations, the wind girder not only provides stability to the tank shell, but is also used to assist in maintaining the cylindrical shape of the tank. Analysis was made possible by LS-DYNA ® 's staged construction functionality. In addition to the standard staged construction keywords, special provisions were required to enable sequential placement of the strakes in deformed but stress- and strain-free states. This was accomplished by running a sub-problem for each successive strake, where the displacement boundary conditions of the sub-problem enforced shell displacement continuity between the current strake and previous strake. Once the constructed shape of the current strake had been determined, it was transferred to the main model. The strake part was then activated in the main model for further analysis, as further foundation differential settlement occurred. Data transfer between the main model and sub-models was accomplished by means of custom Python scripts. The analyses allowed for the quantification of the effect of differential foundation settlement and initial foundation irregularity (while also including the effect of the wind girder) on the final constructed shape of the tank.

• STATE-OF-THE-ART IN THE USE OF (LS-DYNA) FORMING SIMULATION IN HYDROFORMING AND PRECEDING PROCESSES

  A. Haas, H. Bauer, I. Lerch -FH Aalen, M. Mihsein, R. Hall - University of Wolverhampton, A. Böhm - Siempelkamp Pressen Systeme GmbH & Co.

  Rapid and reliable methods for component development and economic manufacturing layout are today crucial factors for the application of hydroforming techniques in mass production of lightweight components for the automotive industry. Optimum design of components taking into consideration special process-specific factors enhances safety and also the cost-effectiveness. The feasibility study, the component configuration and definition of a production sequence are closely interlinked. Once the approximate product geometry or component design, respectively, is known, a FEA (Finite Element Analysis) simulation has to be performed to study the forming process and appropriate die design. The FEA has become an established feature of hydroforming technology. The objective of FEA study is to replace costly and elaborate experimental testing by fast, low-cost computer simulation.

• Statistical Analysis of Process Chains : Novel PRO-CHAIN Components

  Daniela Steffes-lai. Tanja Clees - Fraunhofer Institute for Algorithms and Scientific Computing SCAI

  The robustness of production processes and the quality of resulting products suffer from variations in important material and process parameters, geometry and external influences, which can have substantial and critical influences. Therefore these variations have to be analyzed and transferred over process steps in order to achieve considerably better forecasting quality. We developed the PRO-CHAIN strategy for statistical analysis of sensitivity and stability as well as multi-objective robust design-parameter optimization of whole process chains, even for simulation results on highly resolved grids. PRO-CHAIN constructs an ensemble of simulation results; this data base reflects local variations of functionals. Newly developed PRO-CHAIN components deal with transforming and ensemble compression of the data base via a fast principal component analysis with user-controlled accuracy. Essential features are the classification of design parameters into importance and nonlinearity classes in order to reduce the design space and to get an adequate accuracy for an efficient optimization. In this paper we address the importance of this classification and appropriate kinds of classification measures. Another main novel PRO-CHAIN component is the fast and accurate interpolation of new designs on the whole grid. This interpolation works also for nonlinear applications like crash if the design of experiments is adequate for a high-quality metamodel. The interpolation is based on a nonlinear metamodel with radial basis functions accelerated by a specialized principal component decomposition. Summarized, PRO-CHAIN is now able to fully locally analyze a chain consisting of several process steps with regard to sensitivity and robustness and to predict new designs with user-controlled accuracy. In each step, the influence of parameters onto criteria is classified and sensitivity is measured. PRO-CHAIN is able to propagate the essential scatter due to parameter uncertainty locally over the steps, keeping the necessary number of simulation runs small. Additionally, PRO-CHAIN allows for predicting new designs fully locally, allowing for immediate answers to what-if scenarios, without additional time-spending simulation runs. Thus PRO-CHAIN is a very efficient strategy for statistical analysis of process chains, involving parameter uncertainties, in order to get a robustly optimized solution. Recently, we integrated the efficient interpolation method described into DesParO along with LS- DYNA d3plot readers/writers: on one hand, as a so-called “mixing functionality” for constructing and dumping interpolated results, on the other hand into the novel DesParO Geometry Viewer. Now, DesParO allows for an interactive exploration of the design space, connected with direct interpolation and visualization of the new design and its functionals, like thickness, effective plastic strains and damages as well as statistical measures, locally on the whole grid. Results are presented for the forming-to-crash process chain for a ZStE340 metal blank of a B-pillar. In detail, results of importance and nonlinearity classifications in each process step are shown as well as the prediction of new designs by means of DesParO.

• Statistical Energy Acoustic for High Frequencies Analysis

  M. Souli, R. Messahel (University Lille), Y. T. Zeguer (Jaguar Land Rover), Y. Huang (LSTC)

  For high frequency analysis, Statistical energy analysis (SEA) has proved to be a promising approach to the calculation of sound transmission in complex structures. In automotive industry and also in civil engineering, most of noise transmission is due to high-frequency structural vibrations, where the characteristic wavelength is small compared to the dimensions of the structure.

• Statistical Energy Analysis for High Frequency Acoustic Analysis with LS-DYNA 

  Zhe Cui, Yun Huang (LSTC), Mhamed Souli (Lille University Laboratoire Mecanque de Lille), Tayeb Zeguar (Jaguar Land Rover Limited)

  The present work concerns about the new capability of LS-DYNA  in solving high frequency vibration and acoustic problem, using statistical energy analysis (SEA). As the frequency increases, the number of modes increases. As the result, the traditional numerical methods like finite element (FEM) and boundary element method (BEM) are difficult to use due to the large number elements requirement. It is more practical to consider average responses and their distribution over the structure, using a technique such as statistical energy analysis (SEA). In this paper, several numerical examples are investigated by SEA method with LS-DYNA  . The numerical results are in good agreement with other code.

• Statistics and Non-Linear Sensitivity Analysis with LS-OPT® and D-SPEX

  H. Müllerschön, M. Liebscher - DYNAmore GmbH, Germany, W. Roux, N. Stander - LSTC, U. Reuter - TU Dresden, Germany

  For stochastic simulations usually many simulations are performed, therefore much information is available for the simulation engineer. In order to evaluate this information and to assess the results of stochastic investigations soft- ware tools such as LS-OPT and D-SPEX are available. Good and clearly arranged presentation of the results is important, so that the engineer really benefit from the data mining. D-SPEX is intended to provide features that are not currently implemented in the LS-OPT viewer. Therefore, it is a complement to the visualization capabilities of LS-OPT. Its primary focus is on the visualization of meta-models although it also provides features to visualize stochastic results. D-SPEX is also thought of as a testing platform for new features that might evolve in LS-OPT. By opening the command file of LS-OPT, D-SPEX reads all data of the optimization or robustness project. The current version of D-SPEX is fully compatible with LS-OPT version 3.3. For more information on the features of D-SPEX, see [12].

• Stochastic Analysis and Optimization of Full Vehicle System for Offset Crush

  Hassan El-Hor, Nagappan Sekappan, Hamid Keshtkar - DaimlerChrysler Corporation

  This paper attempts to account for the uncertainties inherited in the parameters involved in the offset crush of full vehicle system. The main objective of this work is to perform a reliability-based analysis to obtain the statistical characteristics of dash and toe intrusion responses in a 40 mph offset crush for a full vehicle system due to manufacture, material and design variability that will be defined in this study. Monte Carlo simulation Method (MCS) will be used in the analysis. Also, a reliability optimization will be performed to search for design solutions for the intrusion that meet the specified requirements on probability of constraint violation on an existing design. Single Loop, Single Variable (SLSV) approach will be used for this analysis. Finally, Six Sigma robust design will be performed to reduce the sensitivity of performance to uncertainties and therefore reduce the probability of constraint violation.

• Stochastic Approach to Rupture Probability of Short Fiber Reinforced Polypropylene for Automotive Crash Applications

  N. Sygusch, B. Lauterbach (Adam Opel); N. Ruesch (Hochschule Darmstadt); S. Kolling (THM Gießen); J. Schneider (TU Darmstadt)

  Due to the ongoing advancements for safety regulations parts made out of fiber reinforced polymers (FRP) gain more and more importance in the area of pedestrian and occupant safety. When studying the rupture behavior of FRP one can observe it’s stochastically distributed nature. Furthermore, these rupture distributions are dependent of fiber orientation angle and strain rate. However, these effects are usually not covered in today’s simulations and simplified rupture criteria are chosen. In crash simulations, for example, rupture of structural parts is assumed to occur when a critical stress or strain threshold is exceeded. Experiments have shown, that the state of rupture is more complex. Rupture behavior of FRP is not restrained to a particular value but is rather described mathematically as a distribution function. Utilizing a spectrum of rupture values instead of a fixed one by incorporating the stochastically distributed rupture behavior into the material model could improve rupture prediction in CAE.

• Stochastic Simulation of Aircraft Fuselage Assembly Considering Manufacturing Uncertainties

  Dietmar C. Vogt, Sönke Klostermann (EADS)

  In aircraft production the use of rivets as permanent mechanical fastener to assemble lightweight sheet metal structures is very common. At assembly the rivet is placed in a through boring and the buck-tail is plastically deformed to create a second head. Thus rivets are positive locking and can carry axial tension loads. However, rivets are mainly used to transfer shear loads via the seating stress of their cylindrical shaft. The remaining pre-stress in the rivet and its local area after the riveting process is subject to immanent manufacturing scatter. When assembling the fuselage of commercial aircrafts additional inherent uncertainties are impacting the riveting process. The cylindrical barrels of a fuselage are typically manufactured from large thin walled shell structures underlying geometric tolerances and variations of the boundary conditions. Managing these uncertainties has a significant impact on the geometrical and structural product quality. In this paper the resulting variations of the three-dimensional residual stress condition will be analysed by simulation. To simulate the fuselage assembly process the model must be able to predict the influence of manufacturing uncertainties appropriately. Therefore these uncertainties will be considered already during the modelling by stochastic parameters and random fields. While most application examples in the literature are quite simple [1], the present paper aims to apply random ® fields in an industrial application using LS-DYNA . By utilizing non-invasive methods the approach can be adapted to different FE-Solvers without too much effort.

• Stochastic Simulations for Crash Worthiness and Occupant Protection

  T. Yasuki (Toyota Motor)

  Reduction of mass of vehicle is a high priority of design targets in automotive industries. To achieve the design targets, several quality control methods are employed in crashworthiness and occupant simulations by LS-DYNA at Toyota Motor Corporation. Some topics using quality control methods in the simulations including LS-TASC are introduced, and its effectiveness and limitations are discussed.

• Stochastic Spray and Chemically Reacting Flow in LS-DYNA

  Kyoung-Su Im, Zen-Chan Zhang, Jr. Grant O. Cook (LSTC)

  The injection of fuel sprays into an automotive engine and liquid jets into a high-speed flow stream is an important process in modern automotive gasoline and diesel engines, and propulsion in gas turbine and supenonic vehicles. ln such applications, the combustion peformance depends strongly on spray atomization, penetration, and the mixing process bemeen the free stream air and the liquid fuel. As a result, the study of liquid spray in such areas has become an important research topic.

• Stone Skipping Simulation by ALE and SPH

  Mitsuhiro Makino - Dynapower Corporation

  Stone skipping is the play at sea shore and river. The flat stone, which is thrown, skips on the surface of water. This phenomena is simulated by ALE and SPH capability of LS-DYNA®. The dependency of the parameters such as the angle between stone and water, incident angle of stone will discuss.

• Strain Rate and Temperature Dependent Testing in Support of the Development of MAT224 and MAT213

  Amos Gilat and Jeremy Seidt, The Ohio State University Department of Mechanical and Aerospace Engineering, Columbus OH, USA

  The deformation and failure of metals and composites is known to be affected by strain rate and temperature. Material models in LS-DYNA® account for these effects and material coupon testing is required for determining the input parameters for the models. The present paper presents a new experimental setup that provide means for investigating the coupled effects of temperature and strain rate during plastic deformation, and new strain rate sensitivity data for fibrous composites that was obtained from static and dynamic tests. Although coupled, the effects of strain rate and temperature are usually determined separately in tests at different strain rates and different initial temperatures, neglecting temperature increase that might be taking place during the deformation. In the present paper a new experimental setup is introduced in which full-field deformation and full-field temperature are measured simultaneously during tensile tests in various strain rates (including high strain rates). The results show a significant rise in the temperature in the necking region even at relatively low strain rates. The data from these tests can be used for determining the Taylor-Quinney coefficient and for determining more accurate parameters in the material models. Limited data is currently available on the response of fibrous composites at high strain rates. New data from testing unidirectional T800/F3900 composite at low and high strain rates shows significant strain rate effect in tension and compression in the 90° direction.

• Strain Rate Dependent Micro-Mechanical Composite Material Model for Finite Element Impact Simulation

  Ala Tabiei, Weitao Yi - University of Cincinnati, Robert Goldberg - NASA Glenn Research Center

  The present study aims at implementation of a strain rate dependent, non-linear, micro- mechanics material model for laminated, unidirectional polymer matrix composites into the explicit finite element code LSDYNA. The objective is to develop an accurate and simple micro- mechanical, rate dependent material model, which is computationally efficient. Within the model a representative volume cell is assumed. The stress-strain relation including rate dependent effects for the micro-model is derived for both shell elements and solid elements. Micro Failure Criterion (MFC) is presented for each material constituent and failure mode. The implemented model can deal with problems such as impact, crashworthiness, and failure analysis under quasi- static loads. The developed material model has a wide range of applications such as jet engine jackets, armor plates, and structural crashworthiness simulation. The deformation response of two representative composite materials with varying fiber orientation is presented using the described technique. The predicted results compare favorably to experimental values.

• Strain Rate Induced Strength Enhancement in Concrete: Much ado about Nothing?

  Leonard E Schwer - Schwer Engineering & Consulting Services

  When concrete impact and penetration simulations are discussed, the question of increased strength due to high strain rates arises. Many concrete material modelers cite and use the seminal work of Bischoff and Perry (1991), or the widely accepted standard reference for concrete Comite Euro-International du Beton (1993) or CEB for short. Bischoff and Perry amassed a large amount of concrete laboratory data addressing strain-rate induced Dynamic Increase Factors (DIF) or the ratio of the measured dynamic to quasi-static strength. Figure 1 is taken from Bischoff and Perry (1991) and shows the large amount of data they collected, along with the strain-rate equations recommended in the CEB for two concrete strengths. The data shows a large amount of scatter in reported strength increases. The depicted CEB equations approximately bound the data. The CEB recommended strain-rate induced strength increase equations are: [ ... ] "It should be noted that the sharp increase predicted at rates greater than 30/s is only tentative, and other recent recommendations [113]1 have also been made which disregard this effect for concrete strength in compression." The data collected by Bischoff and Perry clearly indicates there is some measurable increase in unconfined compressive strength of concrete with increasing strain rate, and we can accept the CEB formulass as being representative of the data. However, the unanswered question is "Does this unconfined compression data translate into the simulations of interest, e.g. blast and penetration of concrete targets, and in particular, do the strain-rate forms used in constitute models?" The above question is addressed in two parts: 1. What do simulations of dynamic unconfined compressive strength tests predict? 2. What do the corresponding simulations of dynamic confined compressive strength tests predict? And, what data, if any, can be used to verify these models.

• Strain Rate Induced Strength Enhancement in Concrete: Much ado about Nothing?

  Leonard E Schwer - Schwer Engineering & Consulting Services

  When concrete impact and penetration simulations are discussed, the question of increased strength due to high strain rates arises. Many concrete material modelers cite and use the seminal work of Bischoff and Perry (1991), or the widely accepted standard reference for concrete Comite Euro-International du Beton (1993) or CEB for short. Bischoff and Perry amassed a large amount of concrete laboratory data addressing strain-rate induced Dynamic Increase Factors (DIF) or the ratio of the measured dynamic to quasi-static strength. Figure 1 is taken from Bischoff and Perry (1991) and shows the large amount of data they collected, along with the strain-rate equations recommended in the CEB for two concrete strengths. The data shows a large amount of scatter in reported strength increases. The depicted CEB equations approximately bound the data. The CEB recommended strain-rate induced strength increase equations are: [ ... ] "It should be noted that the sharp increase predicted at rates greater than 30/s is only tentative, and other recent recommendations [113]1 have also been made which disregard this effect for concrete strength in compression." The data collected by Bischoff and Perry clearly indicates there is some measurable increase in unconfined compressive strength of concrete with increasing strain rate, and we can accept the CEB formulass as being representative of the data. However, the unanswered question is "Does this unconfined compression data translate into the simulations of interest, e.g. blast and penetration of concrete targets, and in particular, do the strain-rate forms used in constitute models?" The above question is addressed in two parts: 1. What do simulations of dynamic unconfined compressive strength tests predict? 2. What do the corresponding simulations of dynamic confined compressive strength tests predict? And, what data, if any, can be used to verify these models.

• Strain Rates in Crashworthiness

  Moisey B. Shkolnikov

  Strain rates related tests, strain rates measurements, strain rates states during vehicle collisions, crashworthiness tests and simulations are discussed in the paper. Several papers (on which some of LS-DYNA strain rates options in constitutive models for metals are based) are considered in this paper from an automotive vehicle crashworthiness point of view. Strain rates effect on structure’s metals during explosions are mathematically described in the papers. The objective of crashworthiness is not (like under explosion) to save a structure, but to sacrifice (making failing in a control manner) the structure to save its occupants during vehicle collisions. Sufficiently taking (during crashworthiness design) into account strain rates in vehicle structures during collisions will increase the structures energy absorption capability and increase their occupants’ survival probability.

• Strain-Rate Dependant Damage Material Model for Layered Fabric Composites with Delamination Prediction for Impact Simulations

  S. Treutenaere, F. Lauro, B. Bennani (University of Valenciennes and Hainaut Cambrésis), T. Matsumoto, E. Mottola (Toyota Motor Europe)

  The use of carbon fabric reinforced polymers (CFRP) in the automotive industry increased very significantly due to their high specific stiffness and strength, their great energy absorption as well as the reduced manufacturing cost. The behaviour understanding and modelling of these materials become essential for their implementation into the design loop, needed for the deployment on mass-produced vehicles. In order to ensure the protection of pedestrians and drivers/passengers in case of collision with a CFRP panel, a model dedicated to the finite element analysis (FEA) of impacts is needed. The nonlinear material behaviour which leads to differences in the impact response of composites is attributed to fibre failure, intra- and interlaminar matrix cracking, fibre-matrix debonding and strain rate sensitivity of the matrix

• Strain-softening in continuum damage models: Investigation of MAT_058

  Karla Simone Gemkow, Rade Vignjevic (Cranfield University)

  Composite materials are of increasing interest to automotive and aviation industry due to their high strength and stiffness. Therefore they are commonly used to replace metallic materials. However their mechanical behaviour is complex, especially when damage is considered. Composite damage leads to degradation of material properties which results in behaviour known as strain-softening. ® An implementation of strain-softening in numerical codes, such as LS-DYNA , leads to mesh sensitivity of results and therefore those models are not reliable. The user of damage models with strain-softening needs a good understanding of those material models to evaluate results critically. This work aims to provide an insight on strain-softening behaviour in a mathematical sense and its consequences on numerical codes. An analytical solution is derived for a one-dimensional dynamic bar problem which allows a direct comparison with numerical results. It was found that deformation localises in an area which is governed by the chosen element size and therefore causes mesh sensitivity. Strain grows infinitely in the strain-softening area with a simultaneous drop of stress. Outside the strain-softening area the problem unloads elastically. The dissipated energy tends to vanish.

• Strength Analysis of Seat Belt Anchorage According to ECE R14 and FMVSS

  Klaus Hessenberger - DaimlerChrysler AG

  To guarantee proper function of the seat belt system, belt anchorages have to resist defined static test loads that represent an vehicular impact. ECE R14 and FMVSS210 are tests to ensure sufficient strength of all anchorage points. In these tests high forces are applied to the seatbelts over loading devices. All components of the sytems, namely seats, seat and belt anchorages have to resist the defined loads without damage. The loads are applied slowly and are sustained over a long period of time, so one can assume a quasi static test. The correct modelling and simulation of the complex load application system is essential for significant and accurate computational results. The experimental test with an existing drivers cab according to FVMSS 210 was simulated with Abaqus Standard (implicit) and LS-Dyna (explicit). During the application of both tools, problems specific to each system were encountered. In Abaqus, problems were caused by large deformations of the sheet structure and possible local buckling phenomenons. In the LS-Dyna calculations the presence of dynamic effects have to be minimized to yield a good correlation with the quasi static tests. The problems encountered and the approach used are presented and a comparison between test and analysis will be given.

• Strength Assessment of a Plastic Component considering local Fiber Orientation and Weld Lines

  Natalja Schafet, Marta Kuczynska (Robert Bosch GmbH), Sascha Pazour, Wolfgang Korte, Marcus Stojek (PART Engineering GmbH)

  The aim of the study was to provide static strength assessments for a short fiber reinforced plastic part considering anisotropic material properties and strength drop caused by weld lines. The sequential coupling of process and structure simulation opens up additional potential for the development process. It is shown how significantly this additional information influences the quality of the assessment. In focus are methods used to assess the strength distribution in the plastic part as well as the comparison between the results of the measurement and final structural-mechanical simulation. More over various failure assessment approaches, ranging from simple estimating procedures, like reduction factors, to the full consideration of fiber orientations, are presented to compare their performance.

• Stress Analysis of Connector Pin Produced by Reverse Stamping Process with LS-DYNA Numerical Simulation and Comparison to Experiments

  Won Yong-Hee, Kim Jeong-Ho, Lee Young-Jun - LG Cable Ltd

  The conventional progressive stamping process used in producing connector pin makes the pin-shift from side to side due to elastic recovery reffered to springback phenomenon. As the solution of this problem, the reverse stamping process was introduced to the production process of connector pin in LG Cable. In this study, we performed research on the feasibility of reverse stamping process to support a design guide of which process. For this research, we tested specimens made of the connector pin materials, and built up the finite element model to simulate the failure mode of the section of the connector pin. The nonlinear analysis for these stamping process was performed using LS-DYNA. Through these nonlinear finite element analysis, we suggest the level of lifter force letting the section shape of the connector pin better and we used LS-DYNA for the practical approach than theoritical appoach.

• Stretching Failure Prediction in LS-PrePost® by a SCL Realized Ductile Failure Criterion

  Z.Q. Sheng, Body Manufacturing, General Motors Company

  The LS-PrePost Scripting Command Language (SCL) is a C like computer language that executed inside LS-PrePost. The SCL enables user to process the simulation results and visualize the resultant data back in the LS-PrePost. In this study, the SCL is used to realize a proposed ductile failure criterion (DFC). With the help of the SCL, the stretching failure in the draw simulation results can be predicted. The effectiveness of SCL is demonstrated by a convenient realization of the proposed DFC, which accurately predicts failure in a rectangular cup draw FEM simulation.

• Structural Analysis of an Automotive Forming Tool for Large Presses Using LS-DYNA

  K. Swidergal , Prof. M. Wagner (OTH Regens­burg), C. Lubeseder, I. von Wurmb, J. Meinhardt (BMW Group), S. Marburg (University of the Federal Armed Forces)

  To improve efficiency in automotive press shops, press systems with increasingly high stroke rates are being implemented, raising thereby the structural dynamic load on the press and especially on the forming tool. A detailed knowledge of the vibrations and resulting critical loads is thus essential for accurate and reliable designs of forming tools. In this paper, dynamic finite element method (FEM) simulation of a selected automotive tool is presented enabling the identification of the vibration of its components. Furthermore regions of critical stress of those structures can be determined.

• Structural Analysis with Vibro-Acoustic Loads in LS-DYNA

  Mostafa Rassaian, JungChuan Lee, Thomas T. Arakawa - Boeing Phantom Works Structures Technology, Yun Huang, Livermore Software Technology Corporation

  Many structures are designed to operate in hot temperature and stringent aero-acoustic fatigue environment, e.g. the engine inlet and the heat shield of aircraft are subject to high temperature and sonic pressure level. It is important to evaluate the dynamic response of the structures exposed to both vibration and acoustic sources of excitations. A new feature of structural analysis with vibro-acoustic loads has been implemented in LS-DYNA®. This feature is based on N-FEARA® finite element analysis tool developed by The Boeing Company. This new capability in LS- DYNA treats the structural response by finite element method coupled with acoustic field based on a known acoustic source behavior by spatial correlation function. The added capabilities enable the users to evaluate the response of structure to both base-excitation, or vibration and acoustic source in the frequency domain. Various acoustic environments and sources of excitations can be considered, including base excitation defining random vibration, in addition to plane wave, progressive wave, reverberant wave, turbulent boundary layer, shock wave, representing various fields for acoustic sources of excitation. Modal acceleration method as well as modal superposition method is used to evaluate the dynamic behavior of structures in the frequency domain. The acceleration power spectral density (PSD) is defined in term of g2/Hz used for vibration analysis. The input spectrum for the acoustic excitations can be either pressure PSD in psi2/Hz or sound pressure level (SPL) in dB. For the latter, sound pressure level is first converted into pressure PSD. The coupling between the structures (represented by the modal shapes) and the acoustic excitations is expressed through the concept of joint acceptance. The results are presented in terms of PSD of the nodal displacements, velocities, accelerations, and element stresses, and the RMS (Root Mean Square) of those variables for a frequency range of interest. Several efficient numerical techniques have been implemented to accelerate the solution phase, including the partition of the panel and subdivision of the range of frequencies. A restart option is provided in case users need to change the input acoustic spectrum or change the range of frequency in the output. Furthermore, this novel feature of LS-DYNA provides users a method to replace an acoustic test environment by a shaker table test as a virtual qualification for testing method. This method is based on a conversion factor between the maximum of root mean square of displacement response due to acoustic pressure load and due to base acceleration load. Several keywords have been introduced in LS-DYNA to facilitate this new feature. Numerical examples are given to demonstrate the new vibro-acoustic analysis capability which will be available in the next release of LS-DYNA.

• Structural Crashworthiness of Rail Vehicles - from the Requirements to the Technical Solutions

  Dr. Markus Seitzberger, Richard Graf, Dr. Philipp Heinzl, Andreas Rittenschober - Siemens Transportation Systems GmbH & Co KG, Sebastian Haupt, Gerhard Schmidt - Siemens AG

  Rail transit provides a very safe means of public transport, which is due to the railroad specific principle of track guidance in combination with high active safety measures during operation. However, train accidents cannot totally be excluded and in the last two decades the subject of passive safety has become an issue of growing importance also in the railway industry. Administrations, operators, railway research institutes, and manufacturers have been active in investigating train collisions and defining relevant recommendations and standards for the realisation of a crashworthy rail vehicle design, providing the last means of protection when all possibilities of preventing an accident have failed. An analysis of structurally significant accidents shows that most fatalities and serious injuries of occupants occur as a result of end-on collisions, often accompanied by overriding of the coach bodies. Consequently, the most effective means of reducing passenger and crew casualties in railway accidents is to concentrate on the design of crashworthy vehicle ends and to avoid overriding, which is also reflected in customer specifications and mandatories, e.g. the British Group Standard GM/RT 2100, the new crashworthiness standard EN15227, the TSI requirements for high speed trains, or the US APTA and FRA regulations. In this paper an overview of current requirements for a structural crashworthiness design of rail vehicles is given. Herein, a focus is put on the new EN15227, which will be the relevant passive safety standard for the next generation of rail vehicles in Europe, covering all kind of passenger carrying rolling stock, from light rail, metro and commuter up to long-distance and high speed main line trains. With regard to design and verification usually a combination of different steps of simulation and prototype testing is applied to consider the individual crash zone design, but also the dynamic behaviour and the crash energy management over the whole train rake. An outline of the methods and tools usually applied for the design and verification process is given. Different examples from Siemens for the development of modern crashworthy trains are shown for both steel and aluminium railway vehicle structures, with an emphasis put on metro and commuter trains. The principles and main challenges of a crashworthiness design are stated and different design variants like car body structures with fully integrated crash zone areas or deformation zones with replaceable attached crash elements are shown. For the latter, particular consideration has to be put on the behaviour under non-perfect loading conditions, e.g. caused by colliding vehicles, which are vertically offset, because such a configuration may be particularly prone to overriding.

• Structural Crashworthiness of Rail Vehicles - from the Requirements to the Technical Solutions

  Dr. Markus Seitzberger, Richard Graf, Dr. Philipp Heinzl, Andreas Rittenschober - Siemens Transportation Systems GmbH & Co KG, Sebastian Haupt, Gerhard Schmidt - Siemens AG

  Rail transit provides a very safe means of public transport, which is due to the railroad specific principle of track guidance in combination with high active safety measures during operation. However, train accidents cannot totally be excluded and in the last two decades the subject of passive safety has become an issue of growing importance also in the railway industry. Administrations, operators, railway research institutes, and manufacturers have been active in investigating train collisions and defining relevant recommendations and standards for the realisation of a crashworthy rail vehicle design, providing the last means of protection when all possibilities of preventing an accident have failed. An analysis of structurally significant accidents shows that most fatalities and serious injuries of occupants occur as a result of end-on collisions, often accompanied by overriding of the coach bodies. Consequently, the most effective means of reducing passenger and crew casualties in railway accidents is to concentrate on the design of crashworthy vehicle ends and to avoid overriding, which is also reflected in customer specifications and mandatories, e.g. the British Group Standard GM/RT 2100, the new crashworthiness standard EN15227, the TSI requirements for high speed trains, or the US APTA and FRA regulations. In this paper an overview of current requirements for a structural crashworthiness design of rail vehicles is given. Herein, a focus is put on the new EN15227, which will be the relevant passive safety standard for the next generation of rail vehicles in Europe, covering all kind of passenger carrying rolling stock, from light rail, metro and commuter up to long-distance and high speed main line trains. With regard to design and verification usually a combination of different steps of simulation and prototype testing is applied to consider the individual crash zone design, but also the dynamic behaviour and the crash energy management over the whole train rake. An outline of the methods and tools usually applied for the design and verification process is given. Different examples from Siemens for the development of modern crashworthy trains are shown for both steel and aluminium railway vehicle structures, with an emphasis put on metro and commuter trains. The principles and main challenges of a crashworthiness design are stated and different design variants like car body structures with fully integrated crash zone areas or deformation zones with replaceable attached crash elements are shown. For the latter, particular consideration has to be put on the behaviour under non-perfect loading conditions, e.g. caused by colliding vehicles, which are vertically offset, because such a configuration may be particularly prone to overriding.

• Structural Design and Analysis of Hit-To-Kill Projectile

  Michael M. Chen - U.S. Army Research Laboratory

  This paper introduces the very first step on the development of a guided ammunition system. It presents high level physics based simulations of a guided 60-mm projectile system, which intention is to enable the sub-projectile to hit and kill an incoming hostile missile at an extended range within a very limited time frame. The projectile requires a very high muzzle exit velocity in order to carry out the mission. Due to high inertia loads derived from immense breech pressure, understanding the survivability of the projectile system during launch becomes very important. The structural system of interest includes sub-projectile body, sabot, penetrator and electronics. This study focuses on overall projectile system configuration design and addresses the concern of structural integrity among components due to propellant pressure forces. LS-DYNA, a popular transient dynamics finite element program, will be adopted to perform in-bore dynamic analysis. The topology of the projectile was initiated based on gun barrel specifications and certain aerodynamics characteristics. Preliminary structural design of sabot and sub-projectile was then performed with pseudo-static analysis. Subsequently, a 3-D finite element model was created and validated by LS-DYNA explicit dynamic analysis. A characteristic centerline variation of a gun barrel was also taken into account in the study. From simulation results, the muzzle velocity reached only 85% of target value due to 25% overweight of the launch package. However, the projectile system shall survive according to effective stress responses. No material failure is anticipated through in-bore travel. It should be noted that the structural configuration is not optimal as far as the launch package mass is concerned. In the next development phase, rigorous optimization efforts will be made on the projectile system, particularly sabot component.

• Structural Design Review of LCD-TV Module by Impact Analysis

  Seong-Sik Choi, Jeoung-Gwen Lee - Samsung Electronics, Korea

  Display performance of LCD is going to be continuously high definition, high brightness, wide viewing angle. On the other hand, outline dimensions are demanded to be slimer and lighter. As the result of above demand, the space of each part becomes gradually narrow and tight. Therefore, the importance of design to prevent weakness for impact is embossed greatly. LCD products have to be subjected to various impact test for consumer's using environments. During the design, toolcorrection or modification caused by damage or large deformation of weak part give rise to time consumption and cost-up. For development of LCD-TV module, these problems become more important because of its large size and heavy weight. To improve these problems, we performed impact analysis of 40 inch LCD-TV module using LS-DYNA and applied the results to the development. In this analysis, we found out the weak regions and obtained improved reliability after design modification. Impact analysis using LS-DYNA is going to be applied in the all of LCD product developments hereafter, and development period reduction and reliability improvement are highly expected.

• Structural Dynamic Response of a Track Chain Complete Undercarriage System using Virtual Proving Ground Approach

  Marco Perillo, Vito Primavera - EnginSoft SpA, Giorgio Bonello, Marco Cavedoni - Italtractor ITM Spa

  ITM Group Engineering Department uses advanced tools as finite element method for static structural analyses of undercarriages, side frames or undercarriage components, as track chain, rollers and tension devices. In order to integrate the recent prototype concepts into this design process combining full system real time dynamic simulations able to represent a typical situation due to operation manoeuvre, experimental test information and 30 years experience of ITM group, a new design procedure is proposed to design and to develop complete undercarriage systems. This paper focuses on the employ of the explicit finite element code LS-DYNA® for predicting reliably the structural behavior of a track chain undercarriage system during usual road obstacles impacts and on the following fatigue life damage analyses of undercarriage (frame components using eta/VPG concept and tools. Part of activity is also developed to investigate how the new simulation procedure could be implemented into ITM Group Engineering Department for increasing design chain efficiency. While the big technical challenge is related to model representation of particular components and to the application of standard operating conditions. Stress and strain field results for full structure and its components are presented and fatigue life of frame principal component is determined and its integrity is evaluated. Finally merits and limits analysis is made in term of quality simulation results, numerical model complexity, design procedure efforts and computational time consuming in comparison to ITM Group Engineering Department experiences.

• STRUCTURAL OPTIMIZATION OF PRODUCT FAMILIES EXPOSED TO CRASH LOADING

  Michael Öman - Linköping University, Sweden

  This paper discusses the problem of structural optimization in product family design and different methodologies are evaluated for weight optimization of components that are common for members in the family. First, the benefits of product family design are presented, followed by a discussion of the complexity of the design problem when the product family is exposed to crash loading and multiple load cases. It is concluded that in large problems the number of combinations of product and load case can get very large and due to the large number of simulations needed, it becomes practically impossible to solve the optimization problem with traditional methods. Therefore, a new methodology is presented that reduces the number of simulations by identifying the most critical combination of product and load case for every boundary condition and iteration. Different optimization methodologies are applied to a family of crash boxes and, finally, results and efficiencies are compared.

• STRUCTURAL OPTIMIZATION USING SPACE MAPPING AND SURROGATE MODELS

  Marcus Redhe - Linköping University, Larsgunnar Nilsson - Engineering Research Nordic AB and Linkoping University

  The aim of this paper is to determine if Space Mapping technique using Surrogate Models in combination with the Response Surfaces Methodology (RSM) is useful in optimization of crashworthiness applications. In addition, the efficiency of optimization using Space Mapping will be compared to conventional structural optimization using the Response Surface Methodology (RSM). To determine the response surfaces, several evaluations must be performed and each simulation can be computationally demanding. Space Mapping technique uses surrogate models, i.e. less costly models, to determine these surfaces and their associated gradients with respect to the object and constraint functions. The original full model is used to correct the gradients from the surrogate model for the next iteration. Thus, the Space Mapping technique makes it possible to reduce the total computing time, needed to find the optimal solution. Two application problems are used to illustrate the algorithm. All examples are constrained optimization problems with one or two design variables. In all applications, the algorithm converged to the optimum solution. For the crashworthiness design problems the total computing time for convergence was reduced with 53% using Space Mapping compared to the conventional RSM. The conclusions are that optimization using Space Mapping and Surrogate Models can be used for optimization in crashworthiness design with maintained accuracy but with a significant reduction in computing time compared to traditional RSM.

• Structural Optimization with the Incremental Equivalent Static Load Method for Nonlinear Dynamic Responses

  Hong Dong, Brian Watson, Juan Pablo Leiva

  This paper presents an efficient approach for optimizing structures under dynamic impact loading conditions. We introduce an improved method called the Incremental Equivalent Static Load Method that enhances the accuracy of the original ESL method. In the original ESL method, equivalent static loads are computed based on the initial geometry and nonlinear displacement results from a nonlinear analysis software. With the Incremental ESL method, we update the stiffness matrix at selected time steps using deformations from a base time step. This enables us to compute and apply equivalent static loads based on incremental displacements for ESL loadcases, resulting in a more precise capture of geometric and material nonlinearity.

• Structure-Fluid Interaction Analysis of an Existing Water Tank

  Mohammad Ghorbanie, Glen Norlander - AMEC Americas

  An analytical study was completed investigating the cause and consequences of significant vibrations resulting from the operation of a hot water storage tank. Deformations and strain readings of the tank wall were measured during the operation and used to calibrate and validate results from the analytical model. The steel storage tank is supported on a concrete foundation. The diameter of the tank is 18 meters and the height is 28 meters. The shell wall thickness varies in steps as plate segments reduce in thickness from 16.2mm at the bottom to 6.7 mm near tank mid height and above. A 64 inch diameter pipe at the top of the tank supplies the inflow water. Three 42 inch and two 36 inch diameter discharge nozzles are located near the bottom of the tank. The tank wall has been observed to be “breathing” at low water levels. These vibrations reduce as the tank water level increases. In order to evaluate the deformations and stress level of the tank, optical measurement of the deformations and strain gauge readings for inflow rates of 4500, 6000 and 8500 m3/hr were performed. The results were then used within a calculation to check for fatigue failure. To study the dynamic behavior of the hot water tank, a set of FE (Finite Element)-CFD (Computational Fluid Dynamics) models were prepared at flow rates of 4500 to 12500 m3/hr. Standard shell elements were used to model the tank shell and both content and inflow water were modeled using the SPH (Smooth Particles Hydraulics) elements available in LS-DYNA®. Interaction between the structure and fluid was defined using contact scenarios. These models were calibrated using the results of strain gauge readings and optical measurements. The size of the elements, geometry and physical properties were decided after numerous test analyses results were adjusted for consideration of certain variables. The final model represented the most critical arrangement considered. Results of the analyses were within an acceptable range of the readings from the strain gauges. Scale factors were used to calibrate the FE results for better compliance. Field measurements and results from the analysis demonstrate stress levels and displacement increase with higher inflow rates.

• Structured ALE Solver with Large Models

  Hao Chen (Ansys Livermore)

  In 2015, LS-DYNA® introduced a new structured ALE (S-ALE) solver option dedicated to solve the subset of ALE problems where a structured mesh is appropriate. As expected, recognizing the logical regularity of the mesh brought a reduced simulation time for the case of identical structured and unstructured mesh definitions. In this paper we will introduce the recent enhancements to facilitate running large models using S-ALE solver.

• Studies on Behavior of Carbon and Fiberglass Epoxy Composite Laminates under Low Velocity Impact Loading using LS-DYNA

  Bhushan S. Thatte, Gautam S. Chandekar, Ajit D. Kelkar - North Carolina A&T State University, Pramod Chaphalkar - Grand Valley State University

  The desired characteristics of materials in modern aircraft applications require high specific modulus and high specific strength for low specific weight. Composite structures, fabricated using carbon and glass fabrics in conjunction with epoxy resin manufactured via the heated vacuum assisted resin transfer molding (H-VARTM) process are now being considered as a low cost alternative to conventional materials without compromising the mechanical properties. It is important to study the response of composite structures under out-of-plane impact loading which may cause considerable damage to the different layers even at low impact energy levels. In the present study, response of composite laminates under low velocity impact loading was investigated using LS-DYNA. The composite laminates were manufactured by the H-VARTM process using basket weave E-Glass fabrics and plain weave AS4 carbon fabrics with the Epon 862 resin system and Epicure-W as a hardening agent. A composite laminate, with 10 layers of carbon and fiberglass fabrics, was modeled using 3D solid elements in a mosaic fashion to represent plain and basket weave patterns. Mechanical properties were calculated by classical micro-mechanical theory and assigned to the elements as orthotropic elastic material properties. The LS-DYNA results were compared with experimental drop test results using the Dynatup Low Velocity Impact Test Machine. The main considerations for comparison were maximum impact load and the energy absorption by the laminates. Progressive damage for fiberglass laminates was reported for six impact energy levels from 128 ft-lbf (incipient damage) to 768 ft-lbf (upper bound) with the increasing increments of 128 ft-lbf. For carbon laminates impact energy levels are half as that of fiberglass.

• Studies on the Efficiency of LS-DYNA in Sheet Metal Stamping for Feasibility and Formability Analyses

  C. Roman (General Motor Company), J. Sun (LSTC), G. Hsiung (General Motor Company), X. Zhu (LSTC)

  Feasibility and formability analyses serve different purposes in automotive panel designing. The turnaround cycle of forming simulation is essential, since the designs change very frequently in early stage of vehicle development. The goal of this study is to evaluate the feasibility by using LS-DYNA ® as an alternative to Autoform for both early product evaluations, as well as more detailed formability analysis in GM’s production developments. Targeting the requirements of feasibility and formability analyses, the key techniques of using LS-DYNA® in sheet metal forming simulations are systematically studied, such as element formulation, material model, adaptive meshing, and mass scaling, etc. The study shows that the simulation time is able to be significantly reduced by choosing proper combination of the numerical parameters, while the accuracy of the results remains satisfying. In this study, 21 production developments by Autoform were translated to LS-DYNA so that they could be run using the LS-DYNA solver on GM’s HPC server. These 21 parts encapsulate all three engineering modules and contain a wide variety of parts. Given the computational resources available in GM, the simulation time and results by LS-DYNA are competitively comparable to Autoform.

• Study of a Driver Airbag Out-Of-Position Using ALE Coupling

  Wenyu Lian - General Motors, Dilip Bhalsod - Livermore Software Technology Corporation

  The new FMVSS 208 regulation specifies the airbag performances under Out-of-Position conditions. During the past 10 years, the thermodynamic-based airbag models have been successfully used in analyzing the occupant interaction with the airbag under regular crash conditions (in-position). However, these models are not suitable for the airbag OOP applications since they can not accurately predict the flow forces that dominate the occupant-airbag interactions under these conditions. Recently, new computational fluid dynamic features were developed, validated and implemented into the current version (v970) of LS-DYNA [1,2,3]. These features, such as the MAT_GAS_MIXTURE gas model, and the POINT_SOURCE inlet flow model, enable users to simulate airbag OOP applications using the ALE coupling techniques. Thus, the influence of design changes, such as the inflator orifice direction, vent locations, and the flow diverse straps in the bag can be investigated. The study of a driver airbag with a 5th%ile dummy under the ISO P2 OOP condition using the ALE coupling techniques is presented here. In this study, the modeling methods for the inflator gas jets, vents, and bag folds are discussed. The results of ALE model are compared with the AIRBAG_HYBRID model and the test data. The ALE simulations show a significant improvement over the HYBRID model. The technical issues associated with OOP simulations, merit & limitations of the current ALE model, and future works are also discussed.

• Study of Drop Test Parameters Using Design of Experiments

  Pritesh Jain, Rushab Oswal, Ameya Khisty, Tata Technologies Ltd

  Various products such as refrigerators, mobile phones, televisions, washing machines, remote controls, telecommunication and military equipment, etc. are subjected to drop tests to assess their fragility and impact tolerance. It is difficult and expensive to understand the effect of various parameters that affect product performance during the test. Finite element simulations using LS-DYNA® effectively help to understand the effect of these parameters. However, as the number of iterations required can be large, design of experiments approach is used in combination with finite element simulation to extract suitable information. Moreover, it is observed that most of the parameters are common across drop test simulations of different products.

• Study of Occupant Lower Leg Injury Value Using Interface New Function

  T. Ishihara, H. Sugaya, K. Maehara, H. Mae (Honda R&D)

  ■ Background In recent years, development at CAE in automotive development is an indispensable technology to shorten the development period and reduce the prototype cost. The crash safety CAE has been used for development as well, but the occupant injury value (especially Lower Leg injury value) is predicted to be greatly affected by deformation of the vehicle frame in addition to modeling of Restraint device. In addition, occupant dummy models contain a large number of soft tissues in order to raise the biofidelity, so there are cases in which the results differ greatly even with a slight difference in the amount of deformation. From the above, in order to predict the influence on lower Leg injury value, a tool is required to examine the influence of body deformation. ■ Objective In order to examine the lower leg injury value due to the frame deformation difference, we developed a function to confirm the sensitivity of the deformation amount difference easily by scaling the deformation amount calculated by the frame CAE, in collaboration with LSTC and JSOL . This function is named Interface_local and will be released in the future In this presentation, we report on the results of verification of the implemented functions and the effects of occupant lower Leg injury values due to differences in frame deformation.

• Study of the Behavior of Dummy Hybrid III Upper Extremities

  Sascha Kutschenreuter, Maxime Dagonet - Takata Petri AG

  Studies of crash simulations resulted in the assumption that an interaction of the upper occupant extremities with the vehicle interior has effects on the occupant loadings, e.g. the chest acceleration. Quantifying this effect requires a dummy model also valid for the area of upper extremities. A suitable test procedure shall help to identify possible force paths via the arms into the dummy torso and, as a result, to evaluate the resulting dummy loadings. This test procedure will be transferred into a virtual model and compared with the results gained in physical testing. The final analysis shows the potential and the limits of the modular FTSS dummy for the quantitative evaluation of interactions between the upper extremities and the vehicle interior.

• Study of the Behavior of Dummy Hybrid III Upper Extremities

  Sascha Kutschenreuter, Maxime Dagonet - Takata Petri AG

  Studies of crash simulations resulted in the assumption that an interaction of the upper occupant extremities with the vehicle interior has effects on the occupant loadings, e.g. the chest acceleration. Quantifying this effect requires a dummy model also valid for the area of upper extremities. A suitable test procedure shall help to identify possible force paths via the arms into the dummy torso and, as a result, to evaluate the resulting dummy loadings. This test procedure will be transferred into a virtual model and compared with the results gained in physical testing. The final analysis shows the potential and the limits of the modular FTSS dummy for the quantitative evaluation of interactions between the upper extremities and the vehicle interior.

• Study of Thin-Walled Box Beams Crushing Behavior Using LS-DYNA

  Yucheng Liu - University of Louisiana

  This paper investigates the dynamic crushing behaviors of steel beams with box cross sections. Systematic parametric studies were conducted in order to reveal the effect of material properties, including strain hardening ratio and strain rate effect, length of the beam, and initial impact velocity on the crushing behaviors of the steel beams. A number of finite element models were constructed with various sets of parameters and used for crashworthiness analyses. Maximum crushing force, mean force, and specific energy absorption (SEA) were recorded after analyses and compared to reflect the influences of parameters. An explicit finite element solver, LS-DYNA®, was used in this study for modeling and analyses.

• Study of Vehicle Aerodynamics with the ICFD Solver and its Application to the Quarkus P3 Pikes Peak Version

  Nicolas Van Dorsselaer, Morgan Le Garrec, Vincent Lapoujade

  The study of external aerodynamics is now an integral part of the development of new vehicles. Indeed, in the current context of reducing energy consumption, it is essential for a vehicle to minimize losses wherever possible. Optimizing external aerodynamics limits the aerodynamic drag generated by the vehicle and therefore optimizes its energy efficiency. Moreover, in a car race context, it is also important to improve downforce to keep the vehicle on track in corners.

• Study on Analytical Verification Method for Dynamic Load Profile-based Joint Design

  J.H. Kim, S.D. Kim, K.T. Lee

  Fastening is clamping and fixing objects using tensile force generated by applying torque to bolts or nuts. In this process, the applied torque doesn’t entirely convert to bolt’s axial force (clamping force); It is mostly lost due to friction, and only a portion is transmitted as axial force. Typically, around 90% of the torque is lost. These frictional losses are influenced by factors like the shape and material of the joint parts and surface finishing. As depicted in Fig.1, even small change in friction coefficient can have a significant impact on the resulting clamping force.

• Study on Blast and Ballistic Loading of Auxetic Composite Sandwich Panels with LS-DYNA

  N. Novak, L. Starčevič, M. Vesenjak, Prof. Z. Ren (University of Maribor)

  Response of novel structures designed for impact, blast and ballistic protection can be enhanced using composite sandwich panels, which are able to extend the energy absorption capabilities [1]. Cellular metals offer very good energy absorption to weight ratio and are consequently used as the core of such composite structures [2]. One of the most promising for this kind of application are auxetic cellular structures, which are modern metamaterials with some unique and superior mechanical properties [3]. They exhibit a negative Poisson’s ratio, i.e. they get wider when stretched and thinner when compressed, as a consequence of their internal structure deformation. The effect of negative Poisson’s ratio is useful for many different applications to enhance properties in density, stiffness, fracture toughness, energy absorption and damping [3]. In case of impact the auxetic material moves towards the impact zone and thus increases the penetration resistance. The conventional cellular materials with a positive Poisson’s ratio in contrast move away from the impact area. The benefits of using auxetic materials as core layers in sandwich panels are obviously crucial to increase the impact energy absorption capability.

• Study on Impact Loading Reduction Performance of "Origami Hat"

  Sunao Tokura, Toshie Sasaki, Ichiro Hagiwara

  With the enforcement of the revised Road Traffic Act, wearing helmets has become a mandatory effort for all cyclists since April 1, 2023 in Japan. However, there are still many people who do not wear helmets. Therefore, we considered developing a foldable helmet that can be easily carried by applying the concept of origami engineering. Origami engineering is a research field proposed with the aim of developing lightweight, high-strength structural components based on the idea of origami, a traditional Japanese paper craft in which various shapes are created by folding paper-like materials. Under the same conditions of the safety test for industrial helmets, a 5 kg striker was dropped from a height of 1.0 m onto a dummy head wearing the hat in which impact energy absorption material was installed, and the impact load received by the dummy head was computed in the simulation. As a result, it was confirmed that it was possible to reduce the impact load by devising the proper material properties and folding shape.

• Study on Optimal Design of Automotive Body Structure Crashworthiness

  Wang Hailiang, Lin Zhongqin, Jin Xianlong - Shanghai Jiao Tong University

  In this paper the optimal model of thin-walled sections of automotive body for structural crashworthiness is built. With computer design of experiment (DOE), the response surface model (RSM) of design can be obtained by carefully choosing a small quantity of samples in the design space. Pareto genetic algorithm (GA) is used in subsequently optimal design. With optimal design of thin-walled sections, the effects of the section parameters such as dimension and thickness on crashworthiness property are researched.

• Study on the Effects of Numerical Parameters on the Precision of Springback Prediction

  Zhongqin Lin, Gang Liu, Weili Xu, Youxia Bao - Shanghai Jiaotong University

  Accurate prediction of springback is the precondition of controlling the springback. The precision of springback prediction is affected by many parameters in both forming process and springback process. The 2-D draw bending benchmark of NUMISHEET’93 is used as an example to investigate the influencing of numerical parameters in LS-DYNA and LS-NIKE3D, which includes solution approach, dynamic effect, number of the dies’ corner elements and blank element size on the springback simulation. Comparing the simulation results with experimental results, some basic principles have been given for springback simulation.

• Study on the Electromagnetic Flux Generation using the new 2D Axisymmetric Capability of Electromagnetism Solver in LS-DYNA

  K. Takekoshi (Terrabyte)

  Study on the electromagnetic flux generation using the new 2D axisymmetric capability of electromagnetism solver introduced in LS-DYNA version R9 will be presented by comparing with the result calculated using 3D electromagnetism solver previously reported.

• Study on Ultra-high Electro-Magnetic Flux Generation using LS-DYNA ® Multi-Physics Capability

  Kunio Takekoshi (Terrabyte Co., Ltd.)

  Simulation results about two kinds of Electro-Magnetic Flux Generation Methods using LS-DYNA Multi-Physics capability are reported in this paper. It is revealed that the Burgess Model should be considered to model electrical conductivity as functions of relative volume as well as temperature, and that hourglass control type 6 should be used in order to precisely predict the generation of magnetic flux density and the deformation of coil for the methods.

• Subject-Specific Modeling of Human Ribs: Finite Element Simulations of Rib Bending Tests, Mesh Sensitivity, Model Prediction with Data Derived From Coupon Tests

  Keegan Yates, Costin Untaroiu, Virginia Tech, Blacksburg, VA, USA

  Rib fractures are common thoracic injuries in motor vehicle crashes. The main objective of this study was to investigate the predictability of subject specific rib models under bending loading. The exterior geometries of two human ribs as well as the boundaries between the trabecular and cortical layers were extracted from corresponding CT-images. Then, the mesh of one rib was developed in a parametric fashion. To investigate the mesh influence on the model response, three models with solid elements (1, 2, 3 elements into rib thickness) and one with shell elements with non-uniform thickness (extracted from CT-images) were developed. The meshes of other rib (4 models for each rib) were obtained using an in-house morphing program specially developed for ribs. Briefly, this algorithm used an automated landmark-based approach to define both the outer and inner boundaries of the cortical layer.

• SuperLIGHT-CAR - the Multi-Material Car Body

  Lutz Berger, Micha Lesemann, Christian Sahr - RWTH Aachen University, Simon Hart, Richard Taylor - ARUP

  Over the last years, total vehicle weights have risen significantly. With their direct influence on the power demand of vehicles, the reduction of weight is one among other measures in order to decrease the fuel consumption and CO2-emissions. The European project SuperLIGHT-CAR (SLC) is aiming at a weight reduction for the body-in-white (BIW) of a compact class passenger car, following the multi- material approach. By this, the perfect material is chosen for every component of the body structure, based on criteria such as energy absorption, structural integrity, stiffness etc.. Simulations are required in order to assess the concept and to show further potential for improvement. LS-Dyna is used in this project to a large extent since it offers excellent opportunities for both static and dynamic load cases that are regarded. The model is therefore built-up from different include files which offer the capability to change quickly between load cases and concept versions. In addition, a multidisciplinary optimisation based on LS-Opt reveals further potential for weight reduction. The main goal of the project, a weight reduction of 30 % for the BIW, is overachieved while the structural performance of the reference vehicle is maintained or even improved. The fact that only one model had to be used for all simulations decreased the required time for a full analysis run and hence accelerated the development process.

• SuperLIGHT-CAR - the Multi-Material Car Body

  Lutz Berger, Micha Lesemann, Christian Sahr - RWTH Aachen University, Simon Hart, Richard Taylor - ARUP

  Over the last years, total vehicle weights have risen significantly. With their direct influence on the power demand of vehicles, the reduction of weight is one among other measures in order to decrease the fuel consumption and CO2-emissions. The European project SuperLIGHT-CAR (SLC) is aiming at a weight reduction for the body-in-white (BIW) of a compact class passenger car, following the multi- material approach. By this, the perfect material is chosen for every component of the body structure, based on criteria such as energy absorption, structural integrity, stiffness etc.. Simulations are required in order to assess the concept and to show further potential for improvement. LS-Dyna is used in this project to a large extent since it offers excellent opportunities for both static and dynamic load cases that are regarded. The model is therefore built-up from different include files which offer the capability to change quickly between load cases and concept versions. In addition, a multidisciplinary optimisation based on LS-Opt reveals further potential for weight reduction. The main goal of the project, a weight reduction of 30 % for the BIW, is overachieved while the structural performance of the reference vehicle is maintained or even improved. The fact that only one model had to be used for all simulations decreased the required time for a full analysis run and hence accelerated the development process.

• Survey of four material models for ballistic simulations of high-strength concrete

  A. Antoniou, M. Kristoffersen, T. Børvik (NTNU)

  This study briefly presents four concrete models used for ballistic impact simulations. The models are the RHT model (*MAT_272 or *MAT_RHT), the CSCM model (*MAT_159 or *MAT_CSCM), the K&C model (*MAT_072R3 or *MAT_CONCRETE_DAMAGE_REL3) and a modified Holmquist-Jonson-Cook model (MHJC). The first three are available as standard models in LS-DYNA with the option to automatically generate their constitutive parameters. The MHJC model has been implemented as a user subroutine. In the present study, we calibrated the MHJC model parameters for C75 high-strength concrete by using laboratory material experiments and data from the literature. Ballistic simulations of C75 concrete slabs impacted by ogival projectiles validated the accuracy of the calibrated parameters. We evaluated the default parameter generation of the former three models compared to the latter.

• Systematic assessment of isogeometric sheet metal forming simulations based on trimmed, multi-patch NURBS models in LS-DYNA

  Christoph Hollweck, Lukas Leidinger, Stefan Hartmann, Liping Li, Marcus Wagner, Roland Wüchner

  Isogeometric sheet metal forming simulation is a promising numerical technique utilized for predicting the behavior of sheet metal parts during the forming process, aiming to establish a stronger connection with Computer Aided Design (CAD) descriptions. This approach combines the well-established framework of traditional finite element analysis (FEA) with the power of non-uniform rational B-splines (NURBS), known as isogeometric analysis (IGA). Unlike the conventional FEA framework, IGA directly employs the ansatz space of the CAD geometry for analysis, thereby enabling analysis on the exact geometry. Additionally, the smoothness of NURBS basis functions offers enhanced simulation accuracy and a larger timestep in explicit dynamics.

• Systems Engineering Approach in Development of Delphi Driver Protection Module (DDPM) by Virtual Engineering

  Mohamed Sahul Hamid, Minoo J. Shah, Jason R. Ridgway, Richard K. Riefe - Delphi Corporation, Troy, MI

  In this paper, the design and development of the Delphi Driver Protection Module (DDPM) using a systems and virtual engineering approach is presented. LS-DYNA software tool was used in virtual prototype studies. The DDPM consists of driver side energy absorbing components. The components included in this module are 1) an adaptive Energy Absorbing (EA) steering column, 2) driver air bag, 3) steering wheel, 4) energy absorbing knee bolster, and 5) adjustable pedals. Each individual component was designed virtually and the virtual design was validated with limited test results. Further, a sub-system mini-sled model using a Blak Tuffy dynamic test was developed to study the functioning of the module due to upper torso loading during a crash. The results of this mini sled model were correlated with actual physical tests. For system level response study, a full finite element sled model was developed. The results of these studies using virtual engineering approach are presented.

• Taking into Account Glass Fibre Reinforcement in Polymer Materials: the Non Linear Description of Anisotropic Composites via the DIGIMAT to LS-DYNA Interface

  Dr. Jan Seyfarth, Dr.-Ing. Matthias Hörmann - CADFEM GmbH, Dr.-Ing. Roger Assaker - e-Xstream Engineering, Chandra S. Kattamuri, Bastian Grass - BSH Bosch und Siemens Hausgeräte GmbH

  In the context of light weight construction the replacement of metal parts with substitutes made from plastic plays a major role. These devices commonly are manufactured through injection moulding and reinforced by different amounts of glass fibres to enhance the strength of the material. In everyday application this poses a challenge to the engineer as due to this processing the local orientation of the reinforcements is varied on a broad scale leading to pronounced different material properties. Finally this can influence the overall stability of the part which is especially true for regions where welding lines occur. In the early stages of the virtual development of such plastic parts it is therefore significant to the take into account the material microstructure while carrying out macroscopic simulations. For explicit calculations non linear material properties, strain rate dependency and the failure of material play an important role in this context. The DIGIMAT to LS-DYNA interface allows to couple microstructure information coming from injection moulding simulations to be integrated in the structural mechanics calculation. Within this approach DIGIMAT is implemented as LS-DYNA user material and offers an independent description of the local composite in each element. The interface uses homogenization schemes which take constitutive laws for fillers and matrix, the percentage of fillers and the filler shape as an input and calculate the average macroscopic stiffness of the material based on the local microstructure. In the standard workflow of a coupled analysis several steps have to be carried out. Within DIGIMAT the constitutional laws are described by mathematical functions. These functions are fitted to the experimental measurements of the material. Usually these experiments are already carried out for fibre reinforced samples leading to the necessity that within DIGIMAT the full composite has to be reverse engineered for the fixed microstructure of the samples. The result is a set of material parameters which can then be taken for a coupled analysis connecting the injection moulding with the structural simulation for the full part under multiaxial load. As both types of simulation usually bear vastly different meshes a preparing step is required in which the local fibre orientations is mapped from the injection moulding mesh to the mesh used in the structural simulation. DIGIMAT offers all tools necessary to carry out the above described steps. In the presentation the workflow of a coupled DIGIMAT to LS-DYNA is demonstrated. Within the virtual material laboratory DIGIMAT-MF the composite is reverse engineered. The resulting parameter set is compared to coupled MOLDFLOW/LS-DYNA calculations on tensile bars under uniaxial strain as well as three point bending. For the application in explicit calculations also failure indicators can be defined within the coupling scheme. As at each step of an analysis DIGIMAT automatically offers all information about the microstructure failure criteria can be derived from the matrix phase or fibre phase separately and used for element deletion within the explicit calculation. All necessary descriptions for composites in explicit simulations can be defined within DIGIMAT, from nonlinear materials over strain rate dependency to failure. On that base the results of a coupled analysis show convincingly better results for an impact through an injection moulded plate than with the conservative approach with isotropic material.

• Taking into Account Glass Fibre Reinforcement in Polymer Materials: the Non Linear Description of Anisotropic Composites via the DIGIMAT to LS-DYNA Interface

  Dr. Jan Seyfarth, Dr.-Ing. Matthias Hörmann - CADFEM GmbH, Dr.-Ing. Roger Assaker - e-Xstream Engineering, Chandra S. Kattamuri, Bastian Grass - BSH Bosch und Siemens Hausgeräte GmbH

  In the context of light weight construction the replacement of metal parts with substitutes made from plastic plays a major role. These devices commonly are manufactured through injection moulding and reinforced by different amounts of glass fibres to enhance the strength of the material. In everyday application this poses a challenge to the engineer as due to this processing the local orientation of the reinforcements is varied on a broad scale leading to pronounced different material properties. Finally this can influence the overall stability of the part which is especially true for regions where welding lines occur. In the early stages of the virtual development of such plastic parts it is therefore significant to the take into account the material microstructure while carrying out macroscopic simulations. For explicit calculations non linear material properties, strain rate dependency and the failure of material play an important role in this context. The DIGIMAT to LS-DYNA interface allows to couple microstructure information coming from injection moulding simulations to be integrated in the structural mechanics calculation. Within this approach DIGIMAT is implemented as LS-DYNA user material and offers an independent description of the local composite in each element. The interface uses homogenization schemes which take constitutive laws for fillers and matrix, the percentage of fillers and the filler shape as an input and calculate the average macroscopic stiffness of the material based on the local microstructure. In the standard workflow of a coupled analysis several steps have to be carried out. Within DIGIMAT the constitutional laws are described by mathematical functions. These functions are fitted to the experimental measurements of the material. Usually these experiments are already carried out for fibre reinforced samples leading to the necessity that within DIGIMAT the full composite has to be reverse engineered for the fixed microstructure of the samples. The result is a set of material parameters which can then be taken for a coupled analysis connecting the injection moulding with the structural simulation for the full part under multiaxial load. As both types of simulation usually bear vastly different meshes a preparing step is required in which the local fibre orientations is mapped from the injection moulding mesh to the mesh used in the structural simulation. DIGIMAT offers all tools necessary to carry out the above described steps. In the presentation the workflow of a coupled DIGIMAT to LS-DYNA is demonstrated. Within the virtual material laboratory DIGIMAT-MF the composite is reverse engineered. The resulting parameter set is compared to coupled MOLDFLOW/LS-DYNA calculations on tensile bars under uniaxial strain as well as three point bending. For the application in explicit calculations also failure indicators can be defined within the coupling scheme. As at each step of an analysis DIGIMAT automatically offers all information about the microstructure failure criteria can be derived from the matrix phase or fibre phase separately and used for element deletion within the explicit calculation. All necessary descriptions for composites in explicit simulations can be defined within DIGIMAT, from nonlinear materials over strain rate dependency to failure. On that base the results of a coupled analysis show convincingly better results for an impact through an injection moulded plate than with the conservative approach with isotropic material.

• TaSC® Product Status

  Willem Roux (LSTC)

  The LS-TaSC product status is presented. The current capabilities are discussed together with illustrative examples and release dates. In addition, the current development directions, such as new capabilities and CAE integration, are also revealed.

• TB11 Test for Short W-Beam Road Barrier

  K. Wilde, S. Burzyński, D. Bruski, J. Chróścielewski (Gdańsk University of Technology)

  In this report we investigate numerical crashtests performed on short section of w-beam road barrier. In typical in-situ test, 60 m section of barrier is tested, while in real life application, shorter sections are often employed. In our numerical analysis, 20 m long section is simulated, hit by 900 kg car at 20°. angle. Total number of 31 simulations were performed, giving insight into cars behaviour and ASI parameter value with variation to initial place of contact along the barrier.

• Techniques for Modeling Torque Transfer between Concentric Cylindrical Components

  Richard Tejeda (InForm Product Development, Inc.)

  Finite elements that use a piecewise linear approximation of geometry are perfectly adequate for modeling cylindrical components such as shafts and hubs in many applications. However, linear elements present a challenge to the assessment of contact interfaces between curved surfaces, namely that faceted surfaces have peaks and valleys that can interlock with each other. A good example is when torque is transferred between a shaft and a hub via a key, collar, pin, or some other means. In this case, it can be difficult or impossible to control how the applied torque is shared between the interlocking mesh and the intended torque transfer device. If the goal of the analysis is to determine the strength of the actual torque transfer features (e.g., a keyway or spline), then it is critical to apply the correct load to them by eliminating or at least minimizing mesh interlocking. This paper discusses various strategies for circumventing the mesh interlocking problem.

• Template-driven management of model and loadcase variants for LS-DYNA simulations

  Irene Makropoulou

  In recent years, crash and safety simulations have reached a very high level of accuracy in the prediction of the crashworthiness of the vehicle and the probability of injury for occupants and pedestrians under a multitude of loading scenarios. Among several factors, this achievement is also attributed to the fine resolution of finite element models that enables the precise representation of even the smallest parts and geometric features affecting the simulation results and the increase in the number of simulated loadcases. However, accuracy does come with a cost: Model size and variability have considerably increased, together with the number of loading scenarios that need to be simulated on each model variant.

• Tensile and Shear Element Erosion in Metal Foams

  S. Szyniszewski (Dept. of Civil Eng., Johns Hopkins University), B. Smith, S. Arwade (Dept. of Civil and Env. Eng., University of Massachusetts), J. Hajjar (Dept. of Civil and Env. Eng., Northeastern University), B. Schafer (Dept. of Civil Eng., Johns Hopkins University)

  The goal of this paper is to simulate fracture observed in tensile and shear tests of steel foam specimens. Deshpande-Fleck plasticity was employed for numerical modeling, and calibrated against compressive and tensile experiments. Steel foam has plastic yield stress, and can deform under compressive load beyond 60% engineering strain. Unlike in compression, steel foam fractures at a small strain in tension. Weak tensile behavior is captured with the element deletion. In order to enhance the realism of the simulated fracture patterns, yield stress, Young modulus, and failure strain were randomly varied between all elements. Unfortunately, default material erosion produced shear fracture patterns significantly different from the experiments. Thus, alternative element erosion was postulated, and it was based on the maximum principal strain. The proposed criterion was shown to give adequate agreement with the experimental results. Tensile and shear fracture modeling of steel foams may benefit from inclusion of spatial variability of material properties. The proposed principal strain based element erosion performed better than the principal stress fracture cut-off.

• Teraflops and Beyond

  Robert F. Lucas - Lawrence Berkeley National Laboratory

• Test and Analysis Correlation of High Speed Impacts of Ice Cylinders

  Edwin L. Fasanella, Richard L. Boitnott - US Army Research Laboratory, VTD, Sotiris Kellas - General Dynamics

  During the space shuttle return-to-flight preparations following the Columbia accident, finite element models were needed that could predict the threshold of critical damage to the orbiter’s wing leading edge from ice debris impacts. Hence, an experimental program was initiated to provide crushing data from impacted ice for use in dynamic finite element material models. A high-speed drop tower was configured to capture force time-histories of ice cylinders for impacts up to approximately 100 ft/s. At low velocity, the force-time history depended heavily on the internal crystalline structure of the ice. However, for velocities of 100 ft/s and above, the ice fractured on impact, behaved more like a fluid, and the subsequent force-time history curves were much less dependent on the internal crystalline structure.

• Test and Analysis Correlation of Foam Impact onto Space Shuttle Wing Leading Edge RCC Panel 8

  Edwin L. Fasanella - US Army Research Laboratory, Vehicle Technology Directorate, Hampton, VA, Karen H. Lyle - NASA Langley Research Center. Hampton, VA, Jonathan Gabrys - The Boeing Company, Philadelphia, PA, Matthew Melis and Kelly Carney - NASA Glenn Research Center, Cleveland, OH

  Soon after the Columbia Accident Investigation Board (CAIB) began their study of the space shuttle Columbia accident, “physics-based” analyses using LS-DYNA were applied to characterize the expected damage to the Reinforced Carbon-Carbon (RCC) leading edge from high-speed foam impacts. Forensic evidence quickly led CAIB investigators to concentrate on the left wing leading edge RCC panels. This paper will concentrate on the test of the left-wing RCC panel 8 conducted at Southwest Research Institute (SwRI) and the correlation with an LS- DYNA analysis. The successful correlation of the LS-DYNA model has resulted in the use of LS-DYNA as a predictive tool for characterizing the threshold of damage for impacts of various debris such as foam, ice, and ablators onto the RCC leading edge for shuttle return-to-flight.

• Test and Numerical Simulation of Fixed Bollard and Removable Bollard Subjected to Vehicle Impact

  Choon-Keat ANG, Siew-Fern LIM, Jing-Yan KONG (Prostruct Consulting Pte Ltd)

  Crash bollard system is a type of physical security measures used to prevent forced entry by vehicles, as well as to provide adequate standoff distance between the target and a Vehicle-Borne Improvised Explosive Device (VBIED). Thus, the design of crash bollard system will have to take into consideration against high- energy vehicle impact and minimizing the post-impacted penetration. In this paper, fixed bollard and removable bollard systems are developed as inelastic transient finite element models. Both systems are simulated against a vehicle crash impact using LS-DYNA analysis tool. Full-scale vehicle crash tests have been carried out to validate the design and analysis.

• Test and simulation approach towards the certification of an aircraft structure subjected to a bird strike

  H. Abdulhamid, F. Plassard (Thiot-Ingenierie)

  Thiot-Ingenierie worked with a compagny specialised in Retrofit packages for the aviation industry. To improve Satcom and connectivity systems, the compagny developed a dedicated structure able to handle a radome with communication means inside. The goal of the project is to design and certify a structure that is an interface between the radome and fuselage. This radome can be subjected to a bird strike and the study aims is to ensure that the loads transmitted by the radome and its interface structure do not cause any critical damage on aircraft fuselage. The challenge of this project was to design the structure within a time development less than 8 months and with only one shot certification test performed at Thiot-Ingenerie laboratory. A development strategy mixing numerical simulations and experimental tests has been performed to get material behavior of composite materials and to numerically optimize the response of the structure. This mixed strategy allowed us to perform the certification test with an improved structure. This method improves the development efficiency to save time and money.

• Test and Simulation Comparison using Titanium Material Models based on MAT224

  Leyu Wang, Sean Haight, Kelly Carney, Paul DuBois, Cing-Dao Kan (George Mason University), Filippo Dicecca (Department of Aerospace Science and Technology), William Emmerling (Federal Aviation Administration)

  Titanium plate impact tests are simulated with *MAT_224, an elasto-visco-plastic material model in LS-DYNA ® with tabulated stress versus strain curves as well as tabulated strain rate and temperature dependency. The *MAT_224 input deck is built upon a series of tensile, shear and compression tests at different strain rates and temperatures conducted on a 0.5" commercial off-the-shelf titanium plate. The input of *MAT_224 is generated so that it predicts all the material property tests conducted on this plate. The 0.5" plate titanium *MAT_224 model is later used to simulate the 0.5" plate impact tests as well as impact tests of the 0.09", 0.14" and 0.25" plates. The predictive performance of the material model for each plate, including exit velocity, failure mode and the profile of the intrusion, are evaluated using the test results. It is shown that the 0.5" plate Ti-6Al-4V *MAT_224 predicts the impact test of the 0.5" titanium plate with great accuracy. However, the predictions for the impact tests of the 0.09", 0.14" and 0.25" plates, using the same material model, are not as accurate. All of these plates meet the specification of AMS-4911, but vary in yield stress from the 0.5” plate, as well as varying between states and material direction. The 0.5 inch plate is the most isotropic and as such most suited for a Von Mises material model. The other plates are from different lots, and clearly have had different processing to produce thinner material thickness. These differences within the same specification are thought to be the cause of the larger difference between test and simulation of the other plates.

• Test Validated Multi-Scale Simulation of a Composite Bumper Under Impact Loading

  Cody Godines, Frank Abdi, Saber Dormohammadi, Michael Lee, AlphaSTAR Corporation, Long Beach, California;, Akbar Farahani, Morteza Kiani, Engineering Technology Associates, Inc. Troy, Michigan

  In a recent USAMP-DOE Validation of Material Models study sought to evaluate efficacy of computational software against physical test. The undertaking started with material characterization and sub-element verification in Phase I and continued to full bumper assembly evaluations. A multiscale ICME building block approach for calibration, verification, and validations resulted in good agreement between test and simulation and served as the foundation for the blind prediction of a composite bumper under impact loading. Comparisons show that simulations, utilizing LS-DYNA® User Material with GENOA’s Multi-Scale Progressive Failure Analysis (MS-PFA), under predicted test displacement vs time and generally over-predicted force curves.

• Testing in Support of the Development of Accurate Numerical Simulations of Plastic Deformation and Failure

  A. Gilat, J. Seidt (The Ohio State University)

  Testing in support of the development of materials models in numerical simulations consists of material characterization tests and validation tests. Testing at various strain rates, temperatures, and loading conditions is used for characterizing plastic deformation and failure of materials. The data from the tests is used for developing constitutive equations (material model) that are utilized in numerical codes that are used for simulations of practical applications. Emphasis in the present paper is on the significance of the Digital Image Correlation (DIC) method for measuring full-field deformations and the development of new tests. It includes the use of DIC in Split Hopkinson (Kolsky) Bar (SHB) tests (compression, tension and torsion), a special apparatus, consisting of a hydraulic actuator and a very long transmitter bar, for tests at intermediate strain rates (50 s-1 –200 s-1), tensile tests with DIC at elevated temperatures (up to 850°C), and simultanious full-field deformation and temperature measurement in tensile tests at low and high strain rates. Many of these tests have been used during in the development of the deformation and failure model (MAT224) in LS-DYNA. The model is based on experimental determination of a failure surface that gives the equivalent plastic strain to failure as a function of stress triaxiality and the Lode parameter. In validation tests material specimens or components are subjected stress states that are different than the ones used for determining the material models. The tests are simulated and predictions of loads, deformation and failure are compared with measurements. Two examples of validation tests, the punch test and the spot weld test, are presented.

• Textile and Composite Modeling on a Near Micro-Scale: Possibilities and Benefits

  O. Döbrich, T. Gereke, C. Cherif (Technical University Dresden)

  Textile materials are increasingly used in civil engineering for the purpose of reinforcing high performance composites, acting as membranes or fulfil technical tasks like filter contaminated media. Therefore, the demand for accurate numerical models which are able to predict the textile mechanics and the forming behaviour of dry and consolidated textiles is increasing and the requirements on the models accuracy and fineness rises. Many numerical models have been introduced in the literature for the different levels of objectivity. For macro-scaled models, complex material models have been carried out to account for the various deformation mechanisms and the anisotropic mechanic of textile fabrics.

• Textile Process Simulation as Part of Process Chain

  H. Finckh, F. Fritz, G. Gresser (Institut für Textil- und Verfahrenstechnik)

  By simulation of the whole textile generation process at a micro-/mesoscopic level, the interaction between machine parts and the textile as well as the threads among each other can be studied in detail. The result is a highly detailed virtual textile which can be either used for further process simulations like draping or virtual testing. In the latter the computation of mechanical properties for macroscopic draping or structural applications can be determined. Enhancements are presented referring braiding simulations using LS-DYNA. It is shown how the braid attaches to a complex change of contour dependent on chosen process and material parameter. Another emphasis is put on a new kind of multiaxial woven fabric called Open Reed Weaving (ORW). Multiaxial weaving technology allows for the addition of two independent thread systems under a nearly arbitrary angle on to the conventional 0°/90° woven fabric. These additional warp fibers can be added partially or covering the whole width of the textile and therefore allowing a wide range of textiles with various designs and textile constructions and also varying materials. The resulting mechanical properties of production parameters shall be investigated by the developed fabric-models. This presentation will give an overview on the newly developed simulation of the multiaxial weaving process and the braiding simulations developed in the BMBF-project DigitPro, a sub-project of the government funded research project Active Research Environment for the Next generation of Automobile (ARENA2036).

• The 3rd Generation Crash Barrier Modeling Method and Application on MPDB

  Y. Wang (VAYU-TECH)

  As the car crash protocol evolves, crash barrier becomes stronger and stronger, Figure 1 shows the deformation comparison of frontal barrier ODB and MPDB, side barrier EU-MDB and IIHS-Side after crashing with a compact SUV, ODB bottoms out while MPDB has half depth left, EU-MDB has very large deformation while most part of IIHS-Side barrier even does not deform.

• The “Shaken Baby” Syndrome; Computational Studies of a New Hypothesis of its Cause

  J.Cheng, S. Cirovic, I.C. Howard, A. Yoxall, M.A. Parsons - The University of Sheffield

  The term “shaken baby syndrome” refers to a unique pattern of non-accidental traumatic injury occurring in children by shaking. Typical injuries include subdural haemorrhage, retinal haemorrhage as well as tears to cortical bridging veins. Infants younger than 6 months are significantly more vulnerable to the shaken baby syndrome than older infants and children, a fact that has been difficult to reconcile with all previous explanations of the phenomenon. The paper explores a new hypothesis for the unique vulnerability of infants (i.e. those younger than about 6 months) to shaking: - the different motions of the brain in skulls with and without the flexibility provided by the fontanelles. The investigation involved the study of two highly simplified finite element models of a skull and brain subjected to shaking, namely, one with a representation of the fontanelle, and one without. The results revealed dangerously enhanced local accelerations and shear strains in the region of the fontanelle. These findings provide a potential mechanism for the special vulnerability of infants to shaking, and suggest some reasons why shaking motions can be much more dangerous than those associated with impact.

• The ACP Process Applied to the FutureSteelVehicle Project: The Future of Product Design and Development

  Akbar Farahani, Paul Dolan, Hamed Sharifi - ETA Inc., Jody Shaw - U. S. Steel, Marc Lambriks - Tata Steel

  WorldAutoSteel launched Phase 2 of its FutureSteelVehicle programme (FSV) with the aim to help automakers optimise steel body structures for electrified vehicles. The Phase 2 objective is to develop detailed design concepts and fully optimise a radically different body structure for a compact Battery Electric Vehicle (BEV) in production in the 2015-2020 timeframe. This paper will provide an overview of the product design methodology and how it was applied to WorldAutoSteel FutureSteelVehicle (FSV) program and result in 35% BIW mass reduction and how it has continued to evolve with each application. The Accelerated Concept to Product (ACP) ProcessTM was applied in this project. The ACP ProcessTM is a proprietary, performance-driven, holistic product design development method, which is based on design optimization. ACP incorporates the use of multiple CAE tools in a systematic process to generate the optimal design solution. The ACP ProcessTM is a methodology that provides solutions, which address the challenges facing the modern product development environment. It achieves this by synchronizing the individual facets of the product development process, resulting in an overall reduction in development costs and time to market. Material selection and utilization, product performance requirements and manufacturing and assembly processes are all considered as early as possible in the design cycle. The resulting design offers a robust and highly efficient solution; which when combined with the strength and design flexibility of Advanced High Strength Steel (AHSS) or other materials; facilitates significant mass reduction for the final design. For the development of a vehicle structure, the methodology offers four key benefits, including a demonstrated capability to reduce product development costs by 40%, reduce product mass by 25% and more, improve product performance (stiffness, durability, NVH, crash/safety, durability) as well as improve fuel efficiency based on the mass reduction results. The paper will further disclose the results of the FSV programme, detailing steel body structure concepts for the aforementioned vehicles that meet aggressive mass targets of 190 kg, while meeting 2015-2020 crash performance objectives as well as total life cycle Greenhouse Gas emissions targets. FSV’s steel portfolio, including over 20 different AHSS grades representing materials expected to be commercially available in the 2015 – 2020 technology horizon, is utilised during the material selection process with the aid of full vehicle analysis to determine material grade and thickness optimisation. Achievement of such aggressive weight reduction with steel will set a new standard for vehicle design approaches for the future. Radically different powertrains, such as the BEV and the PHEV proposed for FutureSteelVehicle, and their related systems make new demands for increasingly efficient body components to handle the new loads. This will require innovative use of AHSS grades and steel technologies to develop structures that are stronger, leaner, greener and affordable. The presentation will explain the “state of the future” design optimisation process used and feature the aggressive steel concepts for structural subsystems incorporated into the FSV structure.

• The ACP Process Applied to the FutureSteelVehicle: The Future of Product Design and Development

  A. Farahani (ETA Inc.), J. R. Shaw (United States Steel Corporation)

  WorldAutoSteel completed FutureSteelVehicle program (FSV) in May of 2011 with the aim to help automakers optimize steel body structures for electrified vehicles. The program objective was to develop detailed design concepts and fully optimize a radically different body structure for a compact Battery Electric Vehicle (BEV) in production in the 2015-2020 timeframe. This paper will provide an overview of the development of an multi- disciplined optimization product design methodology and how it was developed in concert with the WorldAutoSteel FutureSteelVehicle (FSV) program. This optimization technology combined with the advanced high strength steels and the design flexibility of these products enabled 35% BIW mass reduction, exceeding the mass reduction o previous steel programs. This methodology is being made commercially available through the proprietary Accelerated Concept to Product (ACP) ProcessTM. The ACP ProcessTM is a performance-driven, holistic product design development method, which is based on design optimization. ACP incorporates the use of multiple CAE tools (i.e; LS-DYNA) in a systematic process to generate the optimal design solution. The ACP ProcessTM is a methodology that provides solutions, which address the challenges facing the modern product development environment. It achieves this by synchronizing the individual facets of the product development process, resulting in an overall reduction in development costs and time to market. Material selection and utilization, product performance requirements and manufacturing and assembly processes are all considered as early as possible in the design cycle. The resulting design offers a robust and highly efficient solution; which when combined with the strength and design flexibility of Advanced High Strength Steel (AHSS) or other materials; facilitates significant mass reduction for the final design.

• The Advantages of HP-MPI for MPP LS-DYNA

  Yih-Yih Lin - Hewlett-Packard Company

  The standard portable message-passing library MPI is the software tool that drives the parallelism in MPP LS- DYNA. MPI is required to operate in a complex environment: Currently, the major computer architectures include X86, X86_64, and Intel Itanium 2; the major operating systems include Linux, Window, and UNIX; diverse interconnects and switches, using different protocols, are offered by various vendors; and furthermore, in recent years most computer architectures have been evolved into multiple-core from single-core architecture. A well- implemented MPI should achieve the following goals in such a complex environment: (1) supporting all major computer architectures, operating systems, interconnects and switches; (2) being user friendly; (3) being optimized for the performance of the application. In this paper, an in-depth demonstration, using MPP LS-DYNA, on how HP- MPI achieved these goals is presented.

• The ANSA / LS-DYNA approach for IGA Simulations

  L. Rorris (Beta CAE Systems)

  Isogeometric Analysis (IGA), is maturing and becoming capable to be incorporated in industrial applications. Widely used in the automotive industry for crash analysis, LS-DYNA is the first commercial solver to provide IGA features. Highest accuracy and shorter run times make IGA effective for crash analysis. Nevertheless, the complexity of the current automotive models and the maturity of the already established methods and processes require the development of the respective IGA tools and processes to reach and exceed the current levels of effectiveness. The new technical challenges offer the opportunity for new solutions and improvements in engineering simulation technology.

• The Applicability of the Universal HP-MPI to MPP LS-DYNA on Linux Platforms

  Yih-Yih Lin

  In addition to its parallel algorithm, MPP LS-DYNA for cluster computing derives its parallelism from the MPI library and the interconnect. MPI has always had a standard since its inception. On the other hand, there are diverse interconnects and switches in the market, each with unique low-level interface and performance considerations. This variety of interconnects has resulted in a difficult support burden for LSTC, the software developer, and also resulted in inconvenience for MPP LS-DYNA users. To address this difficulty in portability HP-MPI was invented. HP-MPI has enabled a single MPP LS-DYNA executable to work on most prevailing interconnects on a given Linux hardware platform, HP or non-HP. In this paper, the universal applicability of HP-MPI to diverse interconnects on Linux platforms will be verified by the MPP LS-DYNA simulation on the well- known 3-Vehicle-Collision model. Furthermore, it will be shown that the performance of HP-MPI is on a par with, and often better than, other MPI libraries. HP-MPI is ensured with the highest quality because every one of its release is qualified with a suite of 2000 tests. Thus we can safely claim that HP- MPI, being a supported product and requiring no end-users licensing, is the only MPI that MPP LS-DYNA users need on most Linux platforms.

• The Application of a New Material Porosity Algorithm for Parachute Analysis

  Benjamin Tutt - Irvin Aerospace Inc.

  This paper documents the simulation of parachute performance and the role of LS-DYNA in the design of parachutes at Irvin Aerospace Inc. It has long been known that fabric permeability is an important weapon in the arsenal of a parachute designer. In the careful balance of payload rate of descent and parachute stability, the permeability of the parachute material often plays a vital role. The substitution of an impervious material with a highly permeable fabric can turn a parachute from a wandering sloth into a plummeting stabilizer. An accurate consideration of fabric permeability has long eluded the parachute designer. The implementation of a penalty coupling method to describe the interaction of components defined by Eulerian and Lagrangian formulations permits the effect of fabric permeability to be accounted for within the coupling definition. The majority of this paper discusses the implementation of a new porosity algorithm that allows the effect of fabric permeability to be accurately assessed. Correct consideration of material permeability has existed within LS-DYNA for many years, however, these methods were only accurate for the applications originally conceived, namely the airbag. Although both parachute and airbag analyses investigate fabric structures, they differ in many respects, perhaps most significant is that the parachute designer is as concerned about the air that has passed through the parachute as he is with that remaining inside the parachute. Whereas the air that has passed through the airbag is of minimal concern to the automotive engineer. The influence of the air once it has passed through the structural medium can now be assessed within LS-DYNA. This paper provides a level of validation for the technique when considering parachute applications and discusses the importance of this breakthrough to the parachute designer.

• The Application of Optimization and Robustness Technology to a Martian Lander Concept

  Paul Sharp,Royston Jones - Altair Engineering Limited, Richard Slade - Astrium Limited

  Optimization and robustness technologies provide a gateway for the rapid assessment of an engineering design. Following the development of a design concept, optimization technology can automatically modify design variables of the system (i.e. airbag geometry, vent area etc.) to achieve the optimum performance characteristics. Once the design has been optimised, a robustness assessment can be performed. This culminates in the determination of a probability value which provides a scientific basis to quantify the success of a design concept. Many industries require the risk of an engineering operation to be quantified in order to convince licensing authorities or key decision makers. There are fewer clear cut cases where a design is required to perform in an alien environment (i.e. wind velocity, rock height, pitch attitude etc.). The paper showcases new and innovative technology available in Altair HyperStudy to determine optimization and robustness assessments using a minimum amount of LS-DYNA runs.

• The application of the damage & fracture material model to crashworthiness evaluations for Aluminum cars

  Tsuchida T., Yamamoto S. -Toyota Motor Corp., Isomura K. - Toyota Industries Corp.

  In an evaluation of crashworthiness for the cars that are made of aluminum alloys, the evaluations that consider a fracture phenomenon come to be needed because conventional aluminum alloys have low fracture strain (10 - 20%). Since an original damage & fracture material model of LS-DYNA, namely MAT_PLASTICITY_WITH _DAMAGE: MAT81 has a damage & fracture characteristic in case of compressive strain state, real collision phenomena can not be simulated in some cases. Therefore, we reviewed the damage & fracture criterion of this material model. We newly introduced some sort of a damage & fracture criterion into the MAT81 of LS-DYNA V960 in later revision and performed crashworthiness evaluations for an aluminum car using this improved damage & fracture model. This criterion has nondamage & non-fracture characteristic in compressive strain state and it is known as "Orthogonal an-isotropic (Orthotropic) damage & fracture model".

• The Benefit of True Fracture Strain on Material Model Parametrization

  M. Schneider, M. Teschner, S. Westhäuser (Salzgitter Mannesmann Forschung)

  By means of numerical simulation, cars have become much saver and lighter at the same time (when focusing on chassis and body in white). The ongoing improvement of steel grades for the automotive sector has additionally supported this development. Nowadays, the last percentages of improvements can only be obtained by using the latest steel grades and a very realistic modeling of their strain hardening and failure behavior. In case of hot rolled steels with a thickness of 4.0 mm, this leads more and more often to a modeling based on solid finite elements. Focusing hot rolled steels with high yield strength and high formability, there is in addition the need for a modeling of anisotropic hardening.

• The Benefits of Scripting for CAE Engineers – How a Little Can Go a Long Way

  G. Newlands, M. Thornton (ARUP)

  The pressure on a CAE engineer can be great at times, with tight schedules and demands for results. Sometimes the exact tools you require are not available – but what if you could create them yourself? Writing a script or tool to speed up a process may seem daunting, or not worth the effort. Why would you spend a day writing a script to do something when it will take you a couple of hours to actually do the task? The answer is often it will not be the only time you will do the “something”. It might be once, or it may be 10’s or 100’s of times. This is where scripting can really help you. But it is not confined to “speeding things up”. Scripting can be used in a number of areas to aid the CAE engineer: - Custom tools to do exactly what you want. - Custom checks specific to company guidelines to make sure your model is up to scratch. - Model manipulation tools. - Specify a process for others to follow. - And many more… This paper looks at how scripting can have a part to play in the everyday work of a CAE engineer. Using the Oasys LS-DYNA Environment software we will demonstrate the benefits of scripting through a number of worked and real-life examples. We will also show that it is actually very quick and easy to learn and to write useful scripts. Introduction to scripting We will have a brief introduction into the world of scripting, and how you don’t need to spend days and weeks training to gain knowledge and skills that are useful. Pre processing Here we will look at examples of using scripts within the pre-processing environment. This will relate to: - Model assembly. - Model modification. - Building multiple models. - Reading and manipulating external data. - Following a process. - Custom model checking. - Automation. Post processing Here we will look at examples of using scripts within the post-processing environment. This will relate to: - Interrogating and combining LS-DYNA output to produce user defined components that are applicable to your situation. - Automatic post processing of results. Conclusions We will conclude with the benefits of scripting, and how they apply to real world projects.

• THE CASE FOR EXPLICIT FINITE ELEMENT ANALYSIS OF FABRIC SYSTEMS, A PRESENTATION OF REAL WORLD APPLICATIONS AND RESULTS

  A.P. Taylor - Irvin Aerospace Inc

  This paper presents the application of Finite Element Analysis (FEA) to real world problems typically encountered in the Aerodynamic Decelerator Systems field, and to fabric engineering in general. All simulation results are presented from the commercially available Explicit FEA package LS-DYNA, as this has been our most successful application. Our experience with the application of Implicit FEA, is that commercially available codes cannot handle the large deflections associated with fabric systems. The presentation of test to simulation comparisons, now available from several projects, is also presented herein. These provide the reader with a feel for the level of precision/validation possible with today’s simulation tools. Finally, we close with a discussion of where Irvin, and eventually our industry, will apply computational techniques in the coming years.

• The CASIMIR Model for Simulation in Seating Comfort Applications – A Status Update for LS-DYNA

  N. Lazarov, D. Fressmann (DYNAmore), A. Siefert (Wölfel Beratende Ingenieure)

  For those who spend a lot of ti me driving, issues of comfort can become issues of health and safety. Therefore seating comfort is an important point in the seat development. Currently, the OEM and Tier - 1 are mainly using experimental setups with test drivers for the evaluation of seating comfort.

• The Development of the new XJ Jaguar in Advanced Aluminium; Opportunities and Challenges

  Zeguer, T. - Jaguar Cars

• The Digital Prototype as Part of Envyo - Developent History and Applications within the ARENA2036 Environment

  C. Liebold, A. Haufe (DYNAmore); M.Vinot (DLR)

  DigitPro, a sub-project of the government funded research project Active Research Environment for the Next generation of Automobile (ARENA2036) deals with the development of a Digital Protoype, a closed simulation process chain which not only covers different simulation disciplines such as crushing or process analysis, but also various material modeling approaches on the micro-, meso-, and macro level. Various software tools are being used by the project partners, namely the German Aerospace Center (DLR), the Institute of Textile Technology and Process Engineering (ITV), and the Institute of Aircraft Design (IFB) at the University of Stuttgart. Within recent years, the capabilities needed to close the simulation process chain have been implemented into the mapping tool ENVYO® which was officially introduced at last year’s German LS-DYNA users meeting. This paper will give an overview on recently implemented features and will point out the significance of ENVYO® for a closed simulation process chain and data management during the component’s design and verification lifetime. Within this context, an overview on future topics which will be realized within the succeeding project “Digital Fingerprint” will be given.

• The Dynamic Problems in High Speed Transfer Stamping System

  Ming-Chang Yang, Hsing-Chih Tsai and Tien-Chi Tsai - Metal Industries Research and Development Centre

  In this paper the authors would like to disclose the application of LS-DYNA, the dynamic explicit finite element method, in high speed transfer stamping system development. Transfer stamping process has the advantages of material saving and automation especially for stamping parts with complicated geometry. The dynamic effects will be induced as the stamping speed up to 200 SPM i.e. the contact dynamics of barrel cam and followers, transient dynamic effect as grippers contact with blanks and the die swell caused dimension inaccuracy problems, etc. According to the numerical results, we have modified the original design for barrel cam structure and dimension, roller size and transfer bar diameter to enhance the component endurance life. We used the NURBS curves in the cam curves design, which reduced the impact force as the rollers crossed over the contact sides at each groove and traveled smoothly. The gripper designer referred the simulation results to avoid the parts tilting after the grippers closed. All the dynamic problems of transfer system were under controlled via the computer simulation and we have designed our system stamping speed up to 250 SPM successfully.

• The Effect of Element Formulation on FSI Heart Valve Simulations

  G. Luraghi, F. Migliavacca, J. F. R. Matas (Politecnico di Milano)

• The Effect of HDR InfiniBand on LS-DYNA Simulations

  O. Maor, G. Shainer, Y. Qin, D. Cho (HPC-AI Advisory Council)

  From concept to engineering, and from design to test and manufacturing, engineers from a wide range of industries face the ever-increasing need for complex and realistic models to analyze the most challenging industrial problems; Finite Element Analysis is performed to secure quality and speed up the development process. Powerful virtual development software aims to tackle the need for finite element-based Computational LS-DYNA simulations with superior robustness, speed, and accuracy. These simulations are designed to run effectively on large-scale computational High-Performance Computing (HPC) systems.

• The Effect of Inconel-718 High Strain Rate Sensitivity on Ballistic Impact Response using *MAT_224

  Stefano Dolci, Kelly Carney, Leyu Wang, Paul Du Bois, Cing-Dao Kan, Center for Collision Safety and Analysis, George Mason University, Fairfax, VA

  A research team from George Mason University, Ohio State University, NASA and FAA has developed material data and analytical modeling that allows for precise input of material data into LS-DYNA® using tabulation and the *MAT_224 material model. The input parameters of this model are based on data from many experimental coupon tests including tension, compression, impact, shear and biaxial stress states. The material model also includes temperature and strain rate effects. The impact physics of Inconel-718 has been incorporated into LS-DYNA using the *MAT_224 material model. Material model failure is based on the results of tests conducted by Ohio State University under many differing states of stress and differing test geometries and on the ballistic impact tests performed by NASA Glenn Research Center. Validation of the set of material constants for this particular alloy, utilizing the tabulated input method of *MAT_224 includes comparisons both to the mechanical property, and ballistic impact tests, with emphasis given to strain rate and temperature effects. The predictive performance of the *MAT_224 material model, including exit velocity and failure mode are evaluated using the test results. It is demonstrated that the strain rate sensitivity of Inconel-718, at strain rates which are currently difficult to obtain in mechanical property tests, has a significant effect on ballistic impact predictions. *MAT_224 is an elastic-plastic material with arbitrary stress versus strain curve(s) and arbitrary strain rate dependency, all of which can be defined by the user. Thermo-mechanical and comprehensive plastic failure criterion can also be defined for the material. This requires a process of test data reduction, stability checks, and smoothness checks to insure the model input can reliably produce repeatable results. Desired curves are smooth and convex in the plastic region of the stress strain curves.

• The Effect of InfiniBand and In-Network Computing on LS-DYNA® Simulations

  Ophir Maor, Gilad Shainer, David Cho, Gerardo Cisneros-Stoianowski, Yong Qin (HPC-AI Advisory Council)

  High-performance computing (HPC) technologies are used in the automotive design and manufacturing industry. One of the applications is computer-aided engineering (CAE), from component-level design to full analyses for a variety of use cases, including: crash simulations, structure integrity, thermal management, climate control, modeling, acoustics, and more. HPC helps drive faster time-to-market, significantly reducing the cost of laboratory testing and enabling tremendous flexibility. HPC’s strength and efficiency depend on the ability to achieve sustained top performance by driving the CPU performance toward its limits. The motivation for high-performance computing has long been associated with its tremendous cost savings and product improvements; the cost of a high-performance compute cluster can be just a fraction of the price of a single crash test, for example, and the same cluster can serve as the platform for every test simulation going forward. Recent trends in cluster environments, such as multi-core CPUs, GPUs, and advanced high-speed and low latency interconnect with In-Network Computing capabilities, are changing the dynamics of cluster-based simulations. Software applications are being reshaped for higher degrees of parallelism and multithreading, and hardware is being reconfigured to solve new emerging bottlenecks to maintain high scalability and efficiency. Applications like LS-DYNA and others are widely used and provide better flexibility, scalability, and efficiency for such simulations, allowing for larger problem sizes and speeding up time-to-results. CAE applications rely on Message Passing Interface (MPI), the de-facto messaging library for high performance clusters that is used for node-to-node inter-process communication (IPC). MPI relies on a fast, unified server and storage interconnect to provide low latency and a high messaging rate. Performance demands from the cluster interconnect increase exponentially with scale, due in part to all-to-all communication patterns. This demand is even more dramatic as simulations involve greater complexity to properly simulate physical model behaviors. In this paper, we will focus on the value of HDR InfiniBand interconnect technology for LS-DYNA applications, by comparing different InfiniBand network transport options and MPI libraries.

• The Effect of MPI Collective Operations and MPI Collective Offloads on LS-DYNA Performance

  Gilad Shainer, Tong Liu, Pak Lui - Mellanox Technologies, Dave Field - Hewlett-Packard

  From concept to engineering, and from design to test and manufacturing, the automotive industry relies on powerful virtual development solutions. CFD and crash simulations are performed in an effort to secure quality and accelerate the development process. The recent trends in cluster environments, such as multi-core CPUs, GPUs, cluster file systems and new interconnect speeds and offloading capabilities are changing the dynamics of clustered- based simulations. Software applications are being reshaped for higher parallelism and hardware configuration for solving the new emerging bottlenecks, in order to maintain high scalability and efficiency. In this paper we cover new hardware based accelerations and offloads for MPI collectives communications and how is affect LS-DYNA performance and productivity.

• The Effect of using Rigid ISOFIX on the Injury Potential of Toddlers in Near-side Impact Crashes

  Tanya Kapoor, William Altenhof - University of Windsor, Andrew Howard - The Hospital for Sick Children

  This research focuses on the injury potential of children seated in forward facing child safety seats during side impact crashes in a near side seated position. Side impact dynamic sled tests were conducted by NHTSA at Transportation Research Center Inc. using a Hybrid III 3-year-old child dummy in convertible forward/rearward child safety seat. The seat was equipped with a LATCH and a top tether and the dummy was positioned in forward-facing/near-side configuration. The test was completed using an acceleration pulse with a closing speed of 24.1 km/hr, in the presence of a rigid wall and absence of a vehicle body. A fully deformable finite element model of a child restraint seat, for side impact crash investigations, has been developed which has also been previously validated for frontal and far side impacts. A numerical model utilizing a Hybrid III 3-year-old dummy, employing a similar set-up as the experimental sled test was generated and simulated using LS-DYNA®. The numerical model was validated by comparing the head and the chest accelerations, resultant upper and lower neck forces and moments from the experimental and numerical tests. The simulation results were observed to be in good agreement to the experimental observations. Further numerical simulations were completed employing a rigid ISOFIX system with two different cross-sectional geometries for the anchoring mechanism. It was observed from the simulation results that the use of both rigid ISOFIX geometries was effective in reducing resultant chest accelerations by approximately 40 percent. A reduction of approximately 20 to 30 percent was observed in lateral shear and lateral bending of the dummy’s neck. Of the two rigid ISOFIX geometries considered, the cross-shaped system effectively reduced the lateral head displacement by 27 percent (6.8 cm).

• The Effects of Active Muscle Contrac­tion into Pedestrian Kinematics and Injury During Vehicle-Pedestrian Collision

  I. Putra, J. Carmai, S. Koetniyom (King Mongkut’s University of North Bangkok), B. Markert (RWTH Aachen/University of Agder)

  The objective of this study is to develop a finite element model of active human skeletal muscle, which can mimic the contraction behavior of the skeletal muscle and also to analyze the effects of active muscle contraction into pedestrian kinematics and pedestrian injuries during vehicle-pedestrian collision. The skeletal muscles are modeled by combination of solid tetrahedral elements and line beam elements.

• The Effects of Forming and Parameter Mapping on Further Simulation

  Brian Cowell, Anthony Kellicut, Adam Fisher - Tower Automotive

  This paper describes the effects of forming simulation results on crash and durability performance and the impact of the method of transferring results from one simulation to the next. Forming simulation may not always result in a mesh that is ideally suited for static or crash analysis. Tower Automotive has developed software to map forming simulation results from the formed mesh to an entirely different LS-DYNA or NASTRAN mesh of the same part. Simulations of part fabrication represent both hydroforming and mechanical forming. Static simulation is performed in NASTRAN using the work-hardened state as the material input for each element. Other formed parts are subjected to a representative crush load. The effect of transferring results on the same mesh and mapped onto a dissimilar mesh is compared. Results of several crush simulations will be shown, including with forming results, without forming results, and forming results mapped onto a different mesh.

• The Effects of Numerical Result and Computing Time Due to Mass Scaling in Rolling Analysis

  J.Y. Chin, S.W. Lee, S.H. Paik, W.S. Chung - Theme Engineering Inc.

  To enhance the structural performance for vehicle, a patch is attached. For various section shapes, each patch has different performance in energy absorption. In despite of efficient patch, formability may be a problem. Because the depth of groove is about 0.2mm, it needs a large FEM model for rolling analysis and has very small time step. We have to choose a method to reduce analysis time. This paper presents the effects of mass scaling in rolling analysis of a reinforcement patch for vehicle. We examined applicable mass or velocity scaling range. Besides to resolve severe mesh distortion in the sharp pattern forming, we apply efg formulation that is a new function in LS-DYNA version 970 and compare it with standard method.

• The Evaluation of Crashworthiness of Vehicles with Forming Effect

  Hyunsup Kim, Sungoh Hong, Seokgil Hong - KIA Motors, Hoon Huh - Korean Institute of Science and Technology, Korea

  This paper is concerned with a crash analysis for vehicle structures considering forming effects. The properties of formed vehicle structures have been effected and changed by such as work hardening, non-uniform thickness distribution resulted from the forming process. The crash analysis of vehicle structures with the forming effects leads to different results from those without such effects. In this study, the forming effects of the front side member assembly of vehicle structures are considered. The plastic strain and thickness distribution from the simulation results of the forming process have been used as an initial condition for crash analysis. The crash analysis of a full vehicle structure has been performed with those forming effects, and the results are compared to those without the forming effects. The deceleration pulse and deformation from the results are calculated and investigated in order to identify forming effects. Analysis results demonstrate that crash analysis of vehicle structures with forming effects can be more effective for accurate approximation of deceleration pulse and deformation mode.

• The Evolution of Sheet Metal Forming Simulation in Stamping Industry

  Arthur Tang, Wing Lee , Jeanne He - Engineering Technology Associates, Inc., Michigan, C. C. Chen - Dyna Forming Engineering & Technology Sdn. Bhd., Malaysia

  The field of sheet metal forming has experienced numerous innovative changes over the past few decades, such as new forming techniques and application of computer technologies. New forming techniques include application of tailor-welded blank, high strength steel forming, hydroforming, press automation and so on. One of the computer technologies is the implementation of Computer Aided Engineering (CAE), such as sheet metal forming simulation. The application of sheet metal forming simulation has been commonly utilized in the stamping industry to predict the forming feasibility of a wide variety of complex components, ranging from aerospace and automotive components to household products. Since the early 1990s, engineers have adopted LS-DYNA, because of its "incremental solution" capabilities, as their solver of choice for sheet metal forming simulations. Through continuous improvement and implementation, the incremental solution has proven to be accurate, reliable and effective. eta/DYNAFORM with its engine driven by the powerful LS-DYNA solver, has over the years been developed and changed from a FEA oriented approach to a process oriented environment that is most suitable for the tool & die industry. It is widely utilized by the tool and die industry to troubleshooting stamping defects, improving tooling design and product quality. Combining the strengths of the solver accuracy, enhanced computer processing speed, and user-friendly graphic user interface (GUI), eta/DYNAFORM has greatly assisted the tool and die industry in shortening tool making lead time and reducing it’s associated cost. As the demand for sheet metal forming simulation technology accelerates, the need for new technology and requirements have also grown rapidly. In this paper, the evolution of LS-DYNA based sheet metal forming simulation technology from a FEA based environment has been changed to a tooling process based application. The key features include Blank Size Engineering (BSE), Die Face Engineering (DFE), Die Structure Analysis (DSA), Springback Compensation Process (SCP) and Tubular Hydroforming (THF).

• The Future of CAE Software How to Achieve Process Automation

  Brian Huf - Ford Motor Company

  Achieving Process Automation is goal of all software – Automatically do what a user needs to get done. CAE software is no exception. In previous years, technological advances have driven most of the progress in CAE software. CAE software development is now starting to follow the lead of many other software companies by leveraging the concept of Process Guidance (a.k.a. Wizards). This approach has been found to be very effective as well being an advantageous resting spot on the road to Process Automation. Developing and deploying Process Guidance software introduces new questions and opens new possibilities. Several scenarios and strategies are discussed and analyzed. Also included is a list of criteria that could be used to rate prospective software companies on their ability to successfully lead Ford on the path to Process Automation via Process Guidance.

• THE GENERATION OF A MATERIAL MODEL TO REPRESENT THE MECHANICAL BEHAVIOUR OF AN ALIPHATIC POLYETONE (CARILON EP) AT HIGH STRAIN RATE EVENTS AND LOW TEMPERATURES.

  Jerome P. J. Coulton - Advanced Car Technology Systems

  Although explicit finite element codes have been used for many years to predict the impact performance of plastic components, there are few papers that detail how the constants for material models were determined and the resulting models validated with experimental test results. Aliphatic polyetone materials appear very attractive materials for the developers of automotive fuel systems. This is principally due to their low fuel permeability and the stringent total vehicle evaporative requirements. This paper presents the analysis and results of the analysis of experimental test data to determine a material model for an aliphatic polyetone (Carilon EP) at high strain rates and low temperatures. Two different material models are compared (Johnson/Cook and Kruphowsky) with respect to their suitability to modelling Carilon EP and the chosen model validated with high speed impact tests.

• THE IDENTIFICATION OF RATE-DEPENDENT MATERIAL PROPERTIES IN FOAMS USING LS-OPT

  Heiner Müllerschön, Ulrich Franz, Thomas Münz - CAD-FEM GmbH, Nielen Stander - Livermore Software Technology Corporation

  In the past years more and more complex materials, e. g. plastic and metallic foams, honey-comb materials, different types of glues, epoxy-glass materials etc., were incorporated in a wide range of products, particularly in the automotive industry. For the modeling of such materials within nonlinear dynamic problems numerous material models are available in LS-DYNA. However, the application of these material models require the knowledge of the ma-terial parameters describing the behavior of the specific material. The accuracy of the Finite-Element simulations depend authoritatively on the quality of the involved material parame-ters. In order to obtain these material parameters the calibration of the model is necessary through comparison with experimental data. The main objective of this paper is to demonstrate the calibration of a nonlinear material model by minimizing the difference of the model response and the experimental tests. As an example, a low density styrofoam is considered which is described by a material model with strain rate effects (Fu-Chang Model (LS-DYNA, 1999)). The minimization problem is solved via the Response Surface Method (Myers, 1995) using the commercial optimization code LS-OPT.

• The Immersed Smoothed Particle Galerkin Method in LS-DYNA® for Material Failure Analysis of Fiber-Reinforced Solid Structures

  Wei Hu, C. T Wu, Livermore Software Technology Corporation;, Shinya Hayashi, JSOL Corporation

  This paper presents a novel immersed meshfree approach [1-3] for modeling and failure analysis of fiber-reinforced composite solids. The fiber and solid parts are discretized by finite element truss/beam and solid element formulations respectively and independently. This modeling process does not require a conforming mesh. In other words, the fiber elements, e.g. truss or beam elements, are embedded into FEM mesh for immerse computation. The Smoothed Particle Galerkin (SPG) method [4] is employed for the immerse computation. Both fiber inclusion and base material are allowed to fail correspondingly in the nonlinear analysis. Since the base material is modeled by SPG method, a bond-based failure criterion is utilized to model the failure in base material. In contrast, the failure in trust/beam element is modelled by finite element erosion.

• The influence of bird-shape in bird-strike analysis

  S.C. McCallum, C. Constantinou - BAE SYSTEMS

  This paper describes the results of simulations to assess the influence of bird shape during bird-strike. In the first part of this paper, simulations are presented which compare the results of a traditional bird shape model (hemispherical ended cylinder) impacting a square flat panel using the ALE and SPH techniques. In each case the bird is modelled with a mass of 8 lb and has physical dimensions (torso) representative of a Canadian goose. The simulation results show close agreement with one another for stagnation pressure and displacement of the panel. Biometric data obtained from the IBRG (International Bird-Strike Research Group) is then used to construct a more detailed bird model of a Canadian goose that includes multi-material parts. The model is simulated using SPH and compared to the results of the hemispherical ended cylinder. The simulation results obtained using this new bird model indicates that a target may become pre-stressed from the initial impact of the head and neck, prior to the impact of the torso. This may have an important consequence for damage initiation and failure of the target.

• The Influence of Johnson-Cook Parameters on SPH modeling of Orthogonal Cutting of AISI 316L

  A. A. Olleak, H. El-Hofy (Egypt-Japan University of Science and Technology), M. N. A. Nasr (Alexandria University)

  Over the past few decades, there has been a growing interest in modelling of machining processes. In this regard, smoothed particle hydrodynamics (SPH) is one of the latest methods used for that purpose. SPH is a powerful technique that can be used in handling problems of large deformation that are difficult to be tackled using traditional finite element methods. The current work aims to present and evaluate the use of SPH in modelling the machining process.

• The Influence of Permanent Volumetric Deformation on the Reduction of the Load Bearing Capability of Plastic Components

  P.A. Du Bois - Consultant, Germany, S. Kolling - Gießen University of Applied Sciences, Germany, M. Feucht - Daimler AG, Germany, A. Haufe - DYNAmore GmbH, Germany

  During the past years polymer materials have gained enormous importance in the automotive industry. Especially their application for interior parts to help in passenger safety load cases and their use for bumper fascias in pedes- trian safety load cases have driven the demand for much more realistic finite element simulations. For such applica- tions the material model 187 (i.e. MAT_SAMP-1) in LS-DYNA® has been developed. In the present paper the authors show how the parameters for the rather general model may be adjusted to allow for the simulation of crazing effects during plastic loading. Crazing is usually understood as inelastic deformation that exhibits permanent volumetric deformations. Hence a material model that is intended to be applied for polymer components that show crazing effects during the experimental study, should be capable to produce the correct volu- metric strains during the respective finite element simulation. The paper discusses the real world effect of crazing, the ideas to capture these effect in a numerical model and exemplifies the theoretical ideas with a real world struc- tural component finite element model.

• The influence of pretension on reinforced concrete beams subjected to fuel tanker explosions

  Joel Smith, James Bache, Jessica Klimenko, Ben Smith

  Pretension in reinforced concrete beams is commonly used within the construction industry to provide sufficient precompression to the tension face of an element, such that static dead and live loads develop low or no tension stress within the concrete components of the element. While this is advantageous for conventional structural design, allowing the element to carry more load over longer spans, beam elements subjected to significant uplift loading, such as those experienced during an accidental explosion, can develop additional tensile stresses on the element's top surface.

• THE INFLUENCE OF RESIDUAL EFFECTS OF STAMPING ON CRASH RESULTS

  Trevor Dutton, Paul Richardson, Andrew Knight, Richard Sturt - Ove Arup & Partners

  The thickness changes and work hardening arising during the forming process are generally ignored in crash analysis. However, LS-DYNA offers a number of options for quantifying these effects. This paper sets out some recommended methods, and quantifies the effect of the forming process on crash response of a typical car of stamped steel construction. LS-DYNA can also be used for accurate stamping simulation, but in this study a one-step code was used, with the aim of finding the fastest method of generating and including the stamping data. The trade-off between the time taken and accuracy is examined.

• The Influences of Tensile Test Directions and Yield Stress Selections on the FE Results of TBF1180 U-Channel

  Zhiguo Qin, Ching-Kuo Hsiung (General Motor Company)

  There is no standard on how to decide the yield stresses of Advanced High Strength Steel (AHSS) sheet materials. Is it necessary to decide the accurate yield stresses of AHSS materials in stamping FE simulations? A U-Channel part and TBF1180 material were selected to study this question.TBF1180 is a new third generation AHSS sheet metal. Three uniaxial tensile tests on 0 o (L), 45 o (D) and 90 o (T) directions with respect to the rolling direction are available for this material. All the three uniaxial tensile test stress-strain curves and three yield stresses for each tensile curve were used in FE simulations. The simulation results show that the different tensile curves and different yield stresses have the same Draw-Ins. The three tensile curves have limited differences in forming force (2% difference) and springbacks (about 5% difference). The three given yield stresses have very little forming force differences (less than 0.6%), but have big springback differences (up to 46%). Therefore yield stress has big influence on springbacks. What is the relationship between the yield stress and the springbacks and how to decide a yield stress for better formability and springbacks prediction need more study.

• The Investigation of Parachute Suspension Line Fluid-Structure Interactions using LS-DYNA® ICFD

  Catherine P. Barry, Bradford G. Olson, David J. Willis, James A. Sherwood, University of Massachusetts Lowell;, Keith Bergeron, U.S. Army Natick Soldier Research, Development & Engineering Center

  The U.S. Army uses autonomously guided parachute systems to deliver supplies to troops in the field. Each system consists, primarily, of a lightweight canopy, braided polyester suspension lines, and payload. As a system descends, the suspension lines generate and shed vortices as a result of the cross-flow of air, and these vortices induce fluctuating drag and lift forces. These fluctuating forces introduce system performance degradations, and the excited vibrations can often be heard for several kilometers. One method to assist in developing a fundamental understanding of the relationship between the suspension-line architecture, e.g. surface geometry and tensile and torsional stiffnesses, and the associated vortex-induced vibrations is the running of cyber-physical fluid dynamics (CPFD) experiments.

• The Latest Developments of the ANSA Preprocessor for IGA Applications of LS-DYNA®

  Lambros Rorris (BETA CAE Systems International AG), Ioannis Chalkidis (BETA CAE Systems SA)

  Iso Geometric Analysis (IGA), is maturing and becoming capable to be incorporated in industrial applications. Widely used in the automotive industry for crash analysis, LS-DYNA is the first commercial solver to provide IGA features. Better accuracy, potential shorter run times, accurate geometry representation make IGA effective for crash analysis. Nevertheless, the complexity of the current automotive models and the maturity of the already established methods and processes require the development of the respective IGA tools and processes to reach and exceed the current levels of effectiveness. The new technical challenges give the opportunity for new solutions and improvements in engineering simulation technology. During the last year ANSA has developed the needed tools and algorithms to successfully convert CAD geometry to IGA ready part descriptions, thus making the first successful complex hybrid IGA - FEA models possible. We continue our work towards full integration of IGA in current complex LS-DYNA FEA crash models and processes. All latest development will be presented.

• The LS-TaSCTM Multipoint Method for Constrained Topology Optimization

  Willem Roux (LSTC)

  The new multi-point constrained optimization scheme is for the constrained topology design of highly nonlinear structures for which analytical design sensitivity information is hard to compute. These highly nonlinear structures are designed for multiple load cases and multiple constraints, which means that the final design should have load paths for each load case as well as satisfy the constraints. This is done here by using two sets of variables: the local variables describing the part topology on the element level and the global variables consisting of the load case weights and part masses. The two sets of variables are treated differently in the design algorithm: the local variables are computed using a suitable method such as fully stressed design, while the values of the global variables satisfying the constraints are computed using numerical derivatives and mathematical programming.

• The New CE/SE Fluid Solver and Fluid/Structure Coupling

  Zeng-Chan Zhang, Grant O. Cook, Jr. - Livermore Software Technology Corporation

  In this paper, we will discuss a new compressible fluid solver (it will be included with the release of LS980) and its fluid/structure coupling strategy. This fluid solver is based upon the Space-Time Conservation Element and Solution Element Method (or the CE/SE method for short), while a quasi-constraint method is used in the fluid/structure couplings.

• The New Incompressible Flow Capabilities in LS-DYNA

  Mark A. Christon - Livermore Software Technology Corp.

  Over the past year, efforts have been underway to extend LS-DYNA’s extensive list of capabilities to include an incompressible CFD solver. The focus of this paper is on the second-order approximate projection method used in LS-DYNA to solve the time-dependent Navier-Stokes equations. In order to address the computational demands of the implicit pressure field, LS-DYNA relies, in part, upon an A-conjugate projection technique coupled with the preconditioned conjugate gradient method and sub-domain preconditioners. Results of time-dependent laminar and large-eddy simulations are used to illustrate the effectiveness of the projection-based preconditioned conjugate gradient method coupled with the second- order approximate projection flow solver. As a new physics option in LS-DYNA, the incompressible flow solver complements the existing compressible fluid/ALE simulation capabilities.

• The New Paradigm Shift for High-Performance Computing

  Dr. Herbert Cornelius - Intel EMEA

• The new Topcrunch Benchmark Data CAR2CAR for LS-DYNA MPP971R5

  M. Makino (Dynapower Corp.)

  CAR2CAR-ver10 has been used as benchmark data of Topcrunch since 2006. By the enhancement of tied contact in MPP971R5, this data do not work, since the slave nodes of constrained tied contact are released when master segments contain rigid body. CAR2CAR is revised to work for MPP971R5. This paper summarizes tied contact, then explain how to modify the data.

• The Numerical Failure Prediction by the Damage Model GISSMO in Various Materials of Sheet Metal

  S. Chinzei, J. Naito (KOBE Steel)

  Responding to continuous demands for weight saving and enhancement of collision safety of vehicles, high-strength steel sheets are widely used for car bodies. Also, the applications of aluminum sheets are increasing for seeking more lightweight, recently. In applying sheet metals with thinner thickness and higher strength to car bodies, numerical fracture predictions are strongly required to ensure collision safety, since the reduction of ductility becomes key issure for these materials. As a failure model, we use a well examined damage model GISSMO which includes incremental formulation for the description of material instability and localization.

• The Optimization of Servo Press Method for Sheet Metal Forming

  Jun-Ku Lee, Hyun-Cheol Kim (Theme Engineering, Inc.)

  Recently in the field of sheet metal forming, servo press, which can control the speed and position of the tool using a servo motor, is attractive method. Development process of servo press method is accelerated as the capacity of servo motor become bigger. In the future, it’s expected as a great alternative plan to replace conventional press method in order to improve quality, increase productivity, maintain integrity of tools, and reduce energy consumption. Motion control in servo press method has to be effectively optimized depending on the shape and characteristics of the material. However, in the industrial field, the controls of motion relied on experience or intuition of most skilled worker, so the workers can’t avoid many trials and errors to find the optimized motion. We try to implement the servo press method using a finite element analysis with LS-DYNA® in order to shorten the trials and errors [1]. And furthermore, we try to find optimal motion with LS-OPT® [2]. The front side member model of Numisheet 2011 BM03 was chosen for the analysis. We carefully consider stress relaxation and time scaling in order to implement servo press method. Then, we try to compare the following three cases to look into utility of optimized motion for the formability and productivity. - Conventional press method - Conventional press method controlled by speed - Servo press method Finally, we hope that the application of LS-OPT could be effectively used for the optimization of servo press method.

• The Optimization of the LSTC Hybrid III Dummies to enhance the numerical stability and to fulfill the current standards

  Wolfgang Lietz - CAD-FEM GmbH

  • Many years ago LSTC developed Hybrid III-Dummies. One group of these have on the outer surface deformable parts. The dummies are free and without charge for user’s of LS-DYNA. • In the last years on on hand the dummies changed and on the other hand the expectations on the dummies were growing. • This paper describes the the overall validation and optimization process of the whole dummy and in detail the optimization work for the neck validation of the 95% Dummy.

• The Performance of 10-Million Element Car Model by MPP Version of LS-DYNA® on Fujitsu PRIMEPOWER

  Mitsuhiro Makino - Computational Science and Engineering Solution Center, Fujitsu Limited

  In automotive industries, car crash analysis by finite element methods is a very important tool for reducing the development time and cost. In order to get the accurate results, in addition to the improvement of the finite element technology, such as full-integrated shell elements, smaller size of finite element mesh is used, because finer meshes represent the car geometry more accurately, and reduce the noise of contact force. The batch mesh generator, which is enhanced recently, also needs fine mesh. The use of these fine mesh model increases the computational time. In this paper, we examine the performance of the fine mesh model. We developed a 10-million elements car model, which is 10 time larger than the current production car model. The performance of large number of CPU by Massively parallel processing( MPP ) version of LS-DYNA, is measured on Fujitsu PRIMEPOWER.

• The Performance of Car Crash Simulation by LS-DYNA Hybrid Parallel Version on Fujitsu FX1

  Kenshiro Kondo - Fujitsu Limited, Mitsuhiro Makino - DYNAPOWER Corporation

  The number of elements of car simulation for crash analysis has increased rapidly over recent years in order to achieve better accuracy. Several MPP versions of LS-DYNA using variations of MPI have been widely applied to car crash simulation for better job turnaround. The modern computing hardware has been exploring multi-core CPU technology since the performance of single-core can not meet the current and future demands. The Hybrid Parallelization version of LS-DYNA, taking the advantage of multi-core computing platforms, provides an efficient tool for large- model car crash simulation. This hybrid version combines threads parallelization using OpenMP across multiple cores within a node as well as process parallelization using MPI between nodes to achieve maximum parallelization of the analysis. In this paper, we revealed performance bottle neck of MPP version for highly parallelization first; then we showed performance and examined accuracy of solution of LS-DYNA Hybrid version. We tested both 2-million and 10-million elements Caravan crash models on both LS-DYNA MPP and Hybrid versions. The superior performance of Hybrid version demonstrated the feasibility of car crash simulation using massively parallel processors.

• The Performance of Large Car Model by MPP Version of LS-DYNA on Fujitsu PrimePower

  Mitsuhiro Makino - Fujitsu Limited

  In order to get the accurate results, the car models become large and the computational time becomes long. I developed 1.2million elements car models based on NCAC Caravan model, for studying the performance of large number of elements models and large number of CPUs on MPP version of LS-DYNA. 1., The selection of parts of surface to surface contact is sensitive for the large number of CPUs. 2. Soft=2 contact is good performance compared with Soft=1 contact for large number of CPUs

• The Potential Impact of GPUs on LS-DYNA Implicit

  Roger Grimes, Robert Lucas, and Gene Wagenbreth - Livermore Software Technology Corp.

  This talk will report the on-going efforts of LSTC to study the impact of GPUs on LS-DYNA. GPUs offer very high performance computational power at the cost of importing and exporting of data between the host computer and the GPU. The GPU has restricted memory, requires programming in a special language, and suffers performance reduction for double precision arithmetic. Still GPUs appear to offer a potential speed-up of a factor of 2 to 3. Initially our study is focusing on the impact on Implicit Mechanics. The most important computational kernel for Implicit Mechanics is in the direct solution of the sparse systems of linear equations. We will focus on how one can use GPUs for this computational kernel and the probable performance improvement.

• The pressure response in the brain during short duration impacts

  C. Pearce, P.G. Young (University of Exeter), L. Cowlam, and B. Walker (Arup)

  The mechanisms which lead to brain injury in response to blunt head impacts are investigated using three finite-element models of the human head, which range from low to high biofidelity. The models were developed directly from MRI image data using a technique adapted from the marching cubes approach which automates the generation of meshes and allows for a number of different structures (e.g. skull, scalp, brain) to be meshed simultaneously. Experiments were carried out on the finite- element models to validate an analytical representation of head impact based on full 3D elasticity equations developed by one of the authors, and good agreement was observed. The analytical and numerical models were used in parallel to explore the phenomenon of large transient pressure magnification in the brain. This behaviour, proposed by one of the authors, occurs as a result of low duration low velocity impacts. The implications of these high pressure transients are also discussed. Finally individual case studies demonstrate the relevance of this research to realistic head injury scenarios.

• The Recent Developments of the Metal Forming Modules in LS-PrePost ® (1) - The EZSetup and 3D-Drawbead Modules

  Quanqing Yan, Kevin Zhang, Philip Ho, Li Zhang, Yuzhong Xiao, Xinhai Zhu (LSTC)

  New functions have been continuously implemented into LS-PrePost to enhance the metal forming analysis with LS-DYNA. In this paper, two important updates – the EZSetup and the 3D Drawbead - will be introduced. The EZSetup module, which has been used in the production simulations, is further enhanced now by incorporating springback compensation, lancing operation as well as the multi-stage simulation setup with unlimited sets of processes and tools. The 3D Drawbead module, as a newly added metal forming module, can be used to generate the mesh of the real beads given the corresponding line beads. Therefore the accurate simulation with the real beads can be performed readily when the feasibility analysis with the line beads is completed. These modules will be under constant development to meet the requirement of our metal forming users.

• The recent developments of the metal forming modules in LS-PrePost ® (2) - The Die System Module

  Chunjie Zhang, Philip Ho, Yuzhong Xiao, Li Zhang, Xinhai Zhu (LSTC)

  New functions have been continuously implemented into LS-PrePost for users to set up the metal forming simulations with LS-DYNA ® . In this paper, the newly added Die System Module will be briefly introduced. Given the designed part shape, the Die System Module can be used to create the forming tool for the subsequent simulation setup in the EZSetup module of LS-PrePost. The functions that would be needed in the tool creating process are, e.g. flange separation, part tipping, flange unfolding, binder and addendum generation, are provided by the Die System Module in a step-by-step manner. This new module will be under constant development to meet the requirements of our metal forming users.

• The Recent Progress and Potential Applications of Corpuscular Method in LS-DYNA

  Hailong Teng, Jason Wang, Dilip Bhalsod - Livermore Software Technology Corporation

  The corpuscular method is a coarse-grained muti-scale method developed for gas dynamics simulation. It is based on the kinetic molecular theory, where molecules are viewed as rigid particles obeying Newton’s laws of mechanics. Each particle in the corpuscular method represents a group of gas molecules. The only particle-particle and particle--fabric interactions are perfectly elastic collisions. The corpuscular method has been applied to airbag deployment simulation. This paper describes the recent progress of corpuscular method in LS-DYNA®; its application to airbag deployment simulation and other gas related process.

• The Relation between Initial Yaw and Long Rod Projectile Shape after Penetrating an Oblique Thin plate

  M. Arad, D. Touati , I. Latovitz

  The effect of yaw on the ability of an eroding long rod projectile to penetrate oblique thin targets was investigated. Numerical simulations of an eroding long tungsten rod projectile penetrating an oblique thin steel plate target were conducted using the LSDYNA code with a user-written subroutine. The numerical results were found to agree with the experimental data. From the simulation results it may be concluded that following penetration of a thin target, for non-zero initial yaw values, the projectile nose bends toward the velocity vector, while for zero yaw the bending is negligible. In addition, for a non-zero initial yaw angle, the side of the projectile pointing in the direction of its velocity is damaged (this side is in greater contact with the target because of the velocity vector direction).

• The RHT concrete model in LS-DYNA

  Dr. Thomas Borrvall - Engineering Research Nordic AB, Dr. Werner Riedel - Fraunhofer Institut fur Kurzzeitdynamik

  The RHT concrete model is implemented in LS-DYNA. It is a macro-scale material model that incorporates features that are necessary for a correct dynamic strength description of concrete at impact relevant strain rates and pressures. The shear strength of the model is described by means of three limit surfaces; the inelastic yield surface, the failure surface and the residual surface, all dependent on the pressure. The post-yield and post-failure behaviors are characterized by strain hardening and damage, respectively, and strain rate effects is an important ingredient in this context. Furthermore, the pressure is governed by the Mie-Gruneisen equation of state together with a p-α model to describe the pore compaction hardening effects and thus give a realistic response in the high pressure regime. Validations have been performed on smaller test examples and a contact detonation application is presented to illustrate the performance of the proposed model.

• THE ROLE OF CAE MODELLING IN VOLVO SAFETY ENGINEERING

  Ingrid Skogsmo - Director Volvo Cars Safety Centre

  Safety has been a Volvo cornerstone from its founding in 1927, and has remained a fundamental core value since. Within the Ford Motor Company, Volvo Cars has been appointed Centre of Excellence for safety. Continuous development and expansion of the concept of automotive safety involve visionary ideas build on earlier innovative passive and active safety approaches to deliver new "intelligent" solutions designed to neutralize risks of driver error while enhancing motoring enjoyment. The basis for the safety development is a solid understanding of what happens in the real world. Since 1970, Volvo Cars' Accident Research Team has investigated accidents with Volvo cars in Sweden and today we have a database containing more than 36.000 accidents – resulting in valuable in-depth studies as well as comprehensive accident statistics. This knowledge plays an important role when Volvo Cars sets its targets and it is also used as a basis for developing in-house test methods that are similar to real-life accidents, product development and new car projects. Examples of safety systems that have been pioneered as a result of the accumulated experience include the world first systems SIPS (Side Impact Protection System) and WHIPS (Whiplash Protection System), as well as a patented frontal collision structure. Testing, both physical and virtual, and analysis are essential parts in the development of a new car. The Volvo Cars Safety Centre has state-of-the art facilities for car testing, verification and innovative technology that enables us to recreate real traffic situations. Developing a new car model has traditionally been a very test intensive activity. As hardware and software were developed, full car crash simulation and other advanced CAE methods became available, and the product development has become more and more CAE-driven. The ultimate goal - analytical sign off -where production tools are ordered without full scale physical testing, seems to be within reach. To some extent we are already there.

• The Role of LS-DYNA® in the Design of the New London Electric Taxi

  Jamie Dennis, Simon Hart, Arup (Advanced Technology and Research), Solihull, UK

  The iconic London taxi is known worldwide. The London Taxi Company (LTC) has produced this much loved vehicle for many years with few radical changes. Recently, zero-emission legislation in London and the global demand for cleaner vehicles has prompted an evolution in its design. With investment from owner Geely, the newly branded London EV Company (LEVC) will produce several thousand electric taxis per year from its new headquarters in Coventry, UK. The designers, Emerald Automotive Design (EAD), engaged Arup to analyse all structural and safety load cases. This paper discusses how the versatility of LS-DYNA and the modularity of the keyword file enabled Arup to use a single-model approach for all analysis - from full vehicle crashworthiness through to component-level durability checks - and how this facilitated an efficient division of activity between remote teams in the UK and China. The application of both explicit and implicit LS-DYNA to the various load cases is considered, together with the correlation against physical testing. Special challenges were posed by the requirement to comply with Transport for London’s (TfL) Conditions of Fitness and the need to protect the high-voltage components. Reliance on the LS-DYNA predictions was high, with few prototype stages afforded by the accelerated programme. Successful progression directly from simulation to legislative testing sign-off was achieved for cases including pedestrian protection. Arup’s use of LS-DYNA was key in bringing this lightweight bonded aluminium taxi to market, whilst minimising energy consumption and delivering a solution to the issue of sustainable city transport.

• The Shotgun Pellets Interior Ballistics Analysis by Discrete Element Method (DEM) of LS-DYNA®

  Shigan Deng, Ta-Chiang Wu (National Defense University, Taiwan), Jason Wang (Livermore Software Technology Corporation)

  This research used the Discrete Element Method (DEM) of Finite Element Software (LS-DYNA) successfully simulated the interior ballistics performance of shotgun pellets and the deformation of wad and shot cup. This research used 12-gauge shotgun with #9 bird shot which has 433 pellets inside the shot, as an example. There are four components are modeled by finite element: barrel, wad with shot cup, case, and pellets of the shot. The input forces are the chamber pressure on the bottom of wad, which is calculated by Vallier-Heydenreich empirical formula, and the air resistance in the front faces of shot cup. The outputs are velocity/acceleration history of the wad with shot cup and pellets, the distribution of pellets after exits muzzle, and the deformation of the wad with shot cup. The calculated muzzle speed of pellets is 423m/s, compare to 412m/s of Sporting Arms and Ammunition Manufactures Institute (SAAMI) tested, there is only 2.67% error. The results of this research could lead the traditional test-oriented shotgun industry into contemporary Computer Aided Engineering (CAE) by introducing the DEM of FEM to the industry.

• The Significance of the Production Process of FRP Parts for the Performance in Crashworthiness

  Christian Liebold, Andrea Erhart, André Haufe (DYNAmore GmbH)

  As there is a trend in the automotive industry towards using FRP composites for reducing the weight of vehicles, adequate simulation tools to effectively and accurately predict the structural response of composite structures in crashworthiness are needed. Due to the manufacturing induced fiber orientation, which is particularly for short fiber reinforced composites locally varying, the pointwise mechanical behavior of (S)FRP is a priori unknown and accordingly the prediction of the mechanical behavior of FRP-components is challenging. A promising approach is an analysis that covers the complete process chain from the molding process to the crashworthiness modelling: fiber orientation are determined by process simulation and transferred to the structural analysis model through a data-mapper. Using this information, the local anisotropic material behavior can be determined by means of a homogenization procedure and used for the structural analysis. In this paper two recently implemented possibilities for LS-DYNA ® are presented. For the first approach, the data-mapper “DYNAmap” transfers the fiber orientation tensor, which is evaluated in a MoldFlow ® simulation, to the structural analysis model. Using a recently developed constitutive model, pointwise effective anisotropic material properties for this composite are automatically determined and used for the structural simulation. This calculation of homogenized macroscopic properties is done in two steps: At first, effective properties of an associated “pseudo uni-directional” composite are determined by analytical homogenization (see Dvorak [2013]). In a second step an orientation averaging of these uni-directional properties in accordance with the mapped local fiber orientation is carried out; see Advani & Tucker [1987]. While for elasticity the determination of effective properties is done only once in a preprocessing step, for considering inelastic behavior, an update of the material properties during the simulation is necessary from time to time. Alternatively, DYNAmap provides the possibility to perform a homogenization for evaluating the pointwise effective anisotropic elastic stiffness parameters and to transfer the resulting local stiffness values to *MAT_ANISOTROPIC_ELASTIC_PLASTIC. This approach can be extended to an anisotropic elasto-plasticity model with rate dependent hardening. For this purpose, the user has to provide the appropriate Lankford-coefficients and hardening curves, while the mapper provides the dominant fiber orientation pointwise. Damage and failure can be added through *MAT_ADD_EROSION. Within the presentation applications of both approaches will be discussed and compared.

• The Simulation and Formability Prediction of a DP600 Steel Reverse Draw - NUMISHEET 2014 Benchmark 1

  Changqing Du, Kaiping Li (Chrysler Group LLC), Xiaoming Chen (U.S. Steel Corporation), Yuzhong Xiao, Xinhai Zhu (LSTC)

  In this study, the simulation and formability prediction of the DP600 Steel Revers Draw in the NUMISHEET 2014 Benchmark 1 is conducted using LS-DYNA®. The combinations of the material models and element formulations are evaluated for better strain path correlations between the simulation and the measurement at the specified points. Various input factors are considered in this study, including different material model and element type, mesh sizes, integration points and locations. In addition to the conditions given in the benchmark description, extra factors such as the friction effects and springback after drawbead forming process are also considered. The simulation results show that the properly selected yield function is critical for the stain path predictions to be in better agreement with the experimental measurements under such loading condition. In simulation the Formability-Index method is applied to determine the forming limit strains. With this method, the predicted limit strains of the on-set necking points, as well as the locations are compared with the measurement results reported in Benchmark 1 Analysis.

• The Structural Conjugate Heat Transfer Solver - Recent Developments

  T. Klöppel (DYNAmore)

  It is the objective of this contribution to present and discuss recent developments in the structural conjugate heat transfer solver in LS-DYNA to be used mainly for the thermo-mechanical coupled simulation of complex manufacturing processes such as for example hot forming, heat treatment and welding. Beside the multi-physics nature the complexity of these processes is due to the usually challenging constitutive behavior of the employed materials. In the next section some of the thermo-mechanical material models in LS-DYNA are briefly discussed and recent modifications and enhancements to those models are shown. Furthermore, the new material *MAT_GENERALIZED_PHASECHANGE (*MAT_254) is introduced, which features a very flexible and widely applicable modelling approach for phase change kinematics. The paper also addresses two new options for the thermal contact. First of all, heat transfer between a shell edge and a surface (either shell or solid face) can now be considered. Second, a special welding contact formulation has been implemented. Above a certain temperature, the formulation switches from a sliding to a tied formulation and uses different parameters for the heat transfer. Although both modifications have been motivated by welding applications, they have also proven to be helpful for other applications. The presentation of a new heat source boundary condition in the fourth section completes this work’s list of developments. It is defined with the keyword *BOUNDARY_THERMAL_WELD_TRAJECTORY and allows modelling of a moving heat source for coupled and thermal-only simulations and provides a very flexible input for the shape of the heat source.

• The thick shell element type 3

  Andre Stühmeyer - CAD-FEM GmbH

• The use of an Oasys PRIMER model management database during accelerated vehicle development programs such as the 2005 Ford GT

  Tim Keer, Simon Iregbu - Arup

  The role of CAE (Computer Aided Engineering) in the automotive vehicle development process continues to grow in importance. CAE has been one of the key enablers in the recent reduction of vehicle development times, as it allows less reliance on time-consuming and costly prototype testing. Impact CAE has been at the forefront of this CAE revolution. Various additional factors continue to place increased demands on the impact CAE team: The increased number of loadcases required to be analyzed (side o impact alone can require analysis of FMVSS214, SINCAP, IIHS, ECER95 barrier, FMVSS201 pole and EuroNCAP pole impacts, as well as additional OEM-specific loadcases) The increased use of a single underbody for multiple vehicles (e.g. a o sedan and a wagon) The need to analyze different vehicle options (e.g. different powertrains o for front impact; an optional sunroof for side impact) The increased detail in today’s models (in terms of the number of o components modeled as well as the number of elements in the model) Analysis is increasingly expected to be the active driver of the vehicle o design process, not just a passive predictor of performance These factors have combined to place increased pressure on CAE engineers to achieve rapid creation of multiple loadcases for multiple vehicle options. This paper describes a process for management of impact CAE models during vehicle development programs. It is based around the Oasys PRIMER model management software. Arup used this process during the development of the 2005 Ford GT (see Figure 1). Arup performed all the structural CAE for the Ford GT, working for Mayflower Vehicle Systems and Ford Motor Company. The design and analysis of this vehicle has been described elsewhere (Reference 1) and is not repeated here. In this paper, the discussion is limited to the use of Oasys PRIMER Databases and Templates.

• The use of different CSF representations in a numerical head model and their effect on the results of FE head impact analyses

  K. Baeck, J. Vander Sloten, J. Goffin - K.U.Leuven

  To gain better insight in the mechanopathogenesis of brain and skull lesions and to improve the design of protective devices like helmets, finite element (FE) head models are used. Current FE head models have a detailed geometrical description of the anatomical components of the head but often lack an accurate description of the behavior of the cerebrospinal fluid (CSF). Different material properties, mesh resolutions and numerical implementations are used to represent the CSF in those head models. To examine the effect of those different CSF representations on the brain mechanical responses such as strain energy, Von Mises stress, strain and intracranial pressure, this paper starts with the development of a simplified head model and small adaptations are made to the representation of the CSF, both in mesh resolution and constitutive modeling. From this study it follows that depending on which material definition is used for modeling the CSF, the mesh resolution of the CSF can have an important effect on the brain mechanical responses. The study also highlights the need for a more accurate description of CSF material, since the CSF material properties, both material definition and property values, have a significant effect on the results of a head impact analysis.

• The use of Generic Entities for Multidisciplinary preprocessing. A simple but powerful pattern in ANSA

  Yianni Kolokythas, Lambros Rorris - BETA CAE

  Today’s multidisciplinary CAE environment demands for rapid FE Model development cycles, thus the efficient processing of repetitive and complex modeling tasks is vital. This creates a need for highly automated processing steps and effective data sharing between the different CAE disciplines. BETA CAE Systems SA, in order to meet the above requirement, came up with a series of technologies, integrated within its preprocessor ANSA. These technologies allow the handling of the preprocessing environment in the engineering entities level rather in the solver entities level, making possible the treatment of model data as generic engineering data and not as specific FE solver entities. For simple tasks, such as the spotweld connection modeling, to more complex ones, such as a seatbelt or that of a stamping result mapping, there are ANSA entities that hold all the engineering data needed for its realization to the respective e.g. LS-DYNA entities. All the different types of those Generic Entities are similar in their definition and realization. At realization time the generalized entities, automatically adapt to the solver-specific FE (e.g. LS- DYNA). Thus making it straightforward to master the ANSA model-build-up capabilities and share and re-use the engineering data among different disciplines. This technology essentially creates a single, generic, pattern that is re-used throughout ANSA modeling tasks. This pattern driven technology provides a very practical and powerful solution for recurring modeling processes where the engineering data and the solver’s data are kept separately, and associated as required. This paper on ANSA’s Generic Entities presents the latest advances in model build-up technologies in the specific areas of connections and connectors, mass trimming, results mapping, dummy positioning and restraining, pedestrian and FMVSS 201U model set-up. As it is demonstrated, the exploitation of this modeling approach makes the LS-DYNA model built up process more time, effort and cost efficient.

• The use of LS-DYNA fluid-structure interaction to simulate fluid-driven deformation in the aortic valve

  Chris Carmody - MG Bennett & Associates Ltd, Gaetano Burriesci - Sorin Biomedica Cardio, Ian Howard, E.A. Patterson - Sheffield University

• The Use of LS-DYNA for the Development of a Topology-Optimized Thin-Walled Shell Structure Manufactured by Die-Less-Hydroforming

  A. Metzger, T. Ummenhofer (KIT)

  Within the framework of sovereign research at the KIT Steel & Lightweight Structure and an accompanying research project [1], the aim was, following an idea by Ummenhofer and Metzger, to develop a hinged column with a cross-section tapering from the centre to the two ends. The result is an elegant minimalistic pillar called “Hybridstütze PERFECTO” (in English: Hybridcolumn PERFECTO) that is made of an outer thin stainless steel shell, a core of ultra high-strength steel located in the cross section center and a filling of the space in-between by self-compacting concrete.

• The Use of LS-DYNA in the Columbia Accident Investigation and Return to Flight Activities

  Jonathan Gabrys, Josh Schatz - The Boeing Company, Kelly Carney, Matthew Melis - NASA Glenn Research Center, Edwin L. Fasanella - US Army Research Laboratory/VTD, Karen H. Lyle - NASA Langley Research Center

  During the launch of the Space Shuttle Columbia on January 16, 2003, foam originating from the external tank impacted the shuttle’s left wing 81 seconds after lift-off. Then on February 1st, Space Shuttle Columbia broke- up during re-entry. In the weeks that followed, the Columbia Accident Investigation Board had formed various teams to investigate every aspect of the tragedy. One of these teams was the Impact Analysis Team, which was asked to investigate the foam impact on the wing leading edge. This paper will describe the approach and methodology used by the team to support the accident investigation, and more specifically the use of LS-DYNA for analyzing the foam impact event. Due to the success of the analytical predictions, the impact analysis team has also been asked to support Return to Flight activities. These activities will analyze a far broader range of impact events, but not with just foam and not only on the wing leading edge. The debris list has expanded and so have the possible impact locations. This paper will discuss the Return to Flight activities and the use of LS-DYNA to support them.

• The Use of LS-DYNA to Simulate the Water Landing Characteristics of Space Vehicles

  Benjamin A. Tutt, Anthony P. Taylor - Irvin Aerospace Inc

  Irvin Aerospace, Inc. has been involved with the recovery/landing systems of re-entry and interplanetary space vehicles spanning a number of years. A significant aspect in the assessment of recovery and escape systems is the performance of such vehicles in the event of a water landing. One method used to reduce the loads imparted to the crew as the vehicle enters the water is to increase the drag area of the falling body. Increasing the drag area of the recovery system is a simple resolution, however, integration leads to an unfavorable increase in the total system mass and volume requirements. An alternative solution, utilized by the Apollo Earth Landing System, is to dictate the orientation of the vehicle prior to water impact. The results of an exhaustive test program showed that the accelerations experienced by the crew could be reduced by a factor of five simply by changing the vehicle water entry angle. This paper presents an application of the Eulerian-Lagrangian penalty coupling algorithm and multi- material ALE capabilities within LS-DYNA. Documented in the report are the results of a series of validation simulations undertaken by Irvin in an IRAD program to ascertain the capacity of LS-DYNA to replicate the water- landing characteristics of an Apollo Command Module and predict the performance of future landing systems

• The Use of LS-DYNA® Models to Predict Containment of Disk Burst Fragments

  Eric Stamper, Steven Hale - CAE Associates Inc.

  Turbomachinery manufacturers commonly test the centrifugal strength of their rotors in a vertical axis spin test, often called a disk burst test. The design of the containment shell that encloses the disk burst event is critical to ensure the safety of the area surrounding the test. A common method used to design the containment shell for a turbine disk burst test is based on the assumption that the kinetic energy lost by the disk fragments during impact is converted into kinetic energy in the containment shell and energy loss to plastic strain and shear failure in the shell. Containment shells are sized such that the energy required to fail the shell material exceeds the kinetic energy loss during impact. This method is approximate because it assumes fully inelastic impacts and does not account for losses due to friction or heat, nor does it account for stress concentrations in the impact zone or complex disk geometries. ANSYS/LS-DYNA was used to develop an analysis method that could provide more accurate predictions of containment failure limits for a wider range of disk and containment geometries. The ANSYS/LS- DYNA models used a piecewise linear plasticity material law with strain rate dependence, segment based eroding contact , nonlocal failure methods, and a consistent element size. Model results showed good correlation with burst test data [1] relative to the prediction of containment, shell perforation, and overall deformation.

• The Use of User Defined Elements and Extra Degrees of Freedom

  Kelly S. Carney, Paul DuBois (Forming Simulation Technology LLC), Thomas Borrvall (DYNAmore GmbH)

  The capabilities of the LS-DYNA® User Defined Features, allowing for modifications to LS-DYNA analyses, are powerful. It would be impractical to fully exercise their extensive capabilities, and so many of the features have also not been fully documented. Specifically, several undocumented actions are required to use User Defined Elements, when using extra degrees of freedom. This brief paper will explain the additional steps required for the LS-DYNA integrator to update the extra degrees of freedom, when using User Defined Elements. Additional details of extra degrees of freedom usage will also be given.

• The Winfrith Concrete Model : Beauty or Beast ? Insights into the Winfrith Concrete Model

  Len Schwer - Schwer Engineering & Consulting Services

  The so called Winfrith concrete model in LS-DYNA (MAT084 and MAT085) provides: • A basic plasticity model that includes the third stress invariant for consistently treating both triaxial compression and triaxial extension, e.g. Mohr-Coulomb like behavior, • Uses radial return which omits material dilation, and thus violates Drucker’s Postulate for a stable material, • Includes strain softening in tension with an attempt at regularization via crack opening width or fracture energy, • Optional strain rate effects: MAT084 includes rate effects and MAT085 does not, • Concrete tensile cracking with up to three orthogonal crack planes per element; crack viewing is also possible via an auxiliary post-processing file, • Optional inclusion of so called ‘smeared reinforcement.’ This introductory document describes the basic plasticity model, the strain rate formulations and tensile cracking options. The *MAT_WINFRITH_CONCRETE model is another of the so called LS-DYNA ‘simple input’ concrete models, that include the *MAT_PSEUDO_TENSOR (MAT016), *MAT_CONCRETE_DAMAGE_REL3 (MAT072R3) and *MAT_CSCM_CONCRETE (MAT159). The Winfrith model requires the user to specify the unconfined compression and tensile strength. A note on sign convention: in geomechanics compression is usually considered as positive, since most stress states of interest are compressive. However, the Winfrith model uses the standard engineering mechanics convention of compression as negative.

• Theoretical and LS-DYNA® Analysis of Springback Effect on U-Shape Part Top Shape

  Zhiguo Qin, Ching-Kuo Hsiung, General Motors

  In our AHSS U-Shape part springback study, small curvature on the U-Shape part flat top was observed after spring-back. Two mechanics models were used to explain the top bending and unbending deformation processes and the top curve forming mechanism. LS-DYNA simulation results and theoretical analysis results have good correlation. Based on the analysis, 5 methods were proposed to control the flat top spring-back.

• Theoretical Development of an Orthotropic Elasto-Plastic Generalized Composite Material Model

  Robert K. Goldberg and Kelly S. Carney (NASA Glenn Research Center), Paul Du Bois (George Mason University), Canio Hoffarth, Joseph Harrington, Subramaniam Rajan (Arizona State University), Gunther Blankenhorn (LSTC)

  Several key improvements in the state of the art have been identified by the aerospace community as desirable for inclusion in a next generation material model for composite materials to be incorporated within LS-DYNA®. Some of the specific desired features that have been identified include the incorporation of both plasticity and damage within the material model, the capability of using the material model to analyze the response of both three-dimensional solid elements and two dimensional shell elements, and the ability to simulate the response of composites composed with a variety of composite architectures, including laminates, weaves and braids. In addition, a need has been expressed to have a material model that utilizes tabulated experimentally based input to define the evolution of plasticity and damage as opposed to utilizing discrete input parameters (such as modulus and strength) and analytical functions based on curve fitting. To address these needs, a multi-institution consortium has been formed to develop and implement a new composite material model within LS-DYNA. To date, the model development efforts have focused on creating and implementing an appropriate plasticity based model. Specifically, the Tsai-Wu composite failure model has been generalized and extended to a strain-hardening based orthotropic plasticity model with a non-associative flow rule. The coefficients in the yield function are determined based on tabulated stress-strain curves in the various normal and shear directions, along with selected off-axis curves. The non-associative flow rule is used to compute the evolution of the effective plastic strain. Systematic procedures have been developed to determine the values of the various coefficients in the yield function and the flow rule based on the tabulated input data.

• Theory and Evaluation of Concrete Material Model 159

  Yvonne D. Murray - APTEK, Inc.

  The roadside safety community supplements real world crash test data with LS-DYNA simulations performed on the computer. The accuracy of the simulations depends, in part, upon the material models that are formulated to simulate the behavior of the roadside structures and vehicle materials. One important roadside structural material is concrete. A comprehensive concrete material model was developed, implemented in the LS-DYNA finite element code, and evaluated for simulating the deformation and damage to reinforced concrete beams from dynamic impact. For ease of use, default material properties for concrete are incorporated into the model as a function of concrete compressive strength. Correlations with drop tower and bogie vehicle impact tests are used to evaluate the model and finalize the default material properties.

• Thermal Coupling Method Between SPH Particles and Solid Elements in LS-DYNA

  J. Xu, J. Wang (LSTC)

  Smooth particles hydrodynamics is a meshfree, Lagrangian particle method and a simple, yet flexible method for modeling fluid flows and solid bodies in a robust way. It has been applied extensively to the multiphase flows, heat conduction, high explosive problems and so on. For the thermal coupling between any two parts in LS-DYNA, the standard way is through thermal contacts which require the contact areas between those two parts. Due to particle property, SPH particles can handle extremely large deformations, particles can be moved without limitation. In real engineering applications, SPH particles may have very complex free surface and material interface behaviors, including break-up into fragments, and new surfaces will be generated automatically every cycle when interacting with Solid elements. It is quite difficult to update new contact surfaces and calculate the true contact areas between SPH particles and Solid elements. In this paper we introduce a new thermal coupling method between SPH particles and Solid elements through keyword *DEFINE_ADAPTIVE_SOLID_TO_SPH with icpl=3 and iopt=0 options without using thermal contacts, the ghost SPH particles inside the solid elements are used as the coupling medium between original SPH particles and the Solid elements. Some examples are presented to show the robustness of the coupling method.

• Thermal Runaway in Electric Vehicle Crash Simulation using LS-DYNA

  Pierre L’Eplattenier, Inaki Caldichoury, Kevin Kong, Vidyu Challa, Dilip Bhalsod, Srikanth Adya, Mike Howard

  Safety is an important functional requirement in the development of large-format, energy-dense, lithium-ion (Li-ion) batteries used in electrified vehicles. Many automakers have dealt with this issue by enclosing the batteries into robust protective cases to prevent any penetration and deformation during car crashes. While this worked well for first-generation vehicles, consumers are increasingly interested in higher range, which makes overengineered heavy protective cases detrimental for range. A more detailed understanding of battery cell behavior under abuse becomes is therefore necessary to properly make design trade-offs.

• Thermal Structural Forming & Manufacturing Simulation of Carbon and Glass Fiber Reinforced Plastics Composites

  Ala Tabiei and Raguram Murugesan (University of Cincinnati)

  The forming process of composites is presented in this paper. A computational micro-mechanical model of loosely woven fabric is presented and used to simulate the thermos-forming of woven fabric composites. The *PART_COMPOSITE is utilized to represent the resin and woven fabric as integration points through the thickness of the ply. The model, which is incorporated in LS-DYNA ® , accounts for the fiber reorientation, trellis mechanism of the yarn and viscoelasticity of the fibers. The resin material model used is a temperature dependent elastic plastic thermal. The behavior of the woven fabric is studied with the classical hemispherical draping and cantilever bending simulations which are validated against experiments. The thermal structural analysis of the carbon/epoxy woven fabric composites is carried out through the bias extension and thermo-forming simulations. This method of incorporating the resin within integration points of the fabric proved satisfactory as the simulation results were in good agreement with the experiment. The proposed model and simulation techniques would be an efficient tool in evaluating factors related to the composite manufacturing process.

• Thermal-Structure Coupling Simulation Analysis on Rolling Process of H-shape Steel

  Zhiyuan Shi - ShouGang Steel Group, Guoming Zhu - University of Science and Technology Beijing

  Today CAE technology is seeing its rapid development and got widely application in nearly all industries. For metallurgy CAE is also becoming the highlight in many specialties and playing important roles in process optimization and property prediction for R&D of new product development. In this paper a typical example, i.e. thermal-structure coupling simulation analysis on rolling process of H-shape steel with LS-DYNA is introduced.

• Thermo-Mechanical Approach Using LS-DYNA® to Predict Tool Shape for Insert Molded ARPRO® (EPP) Rear Seat Cushion/Riser

  Nurul Huda, JSP International

  Shrinkage and warpage is widely observed phenomenon in molding process where parts are molded at a higher temperatures than the ambient temperature. This paper demonstrates thermo-mechanical approach in aiding to design an insert molded ARPRO® (EPP) seat cushion. When the molded ARPRO® seat cushion is being ejected from press at high temperature than ambient, and, cools down to ambient temperature - it deforms due to thermal shrinkage. This deformation causes final part to warp and results in myriad of issues in achieving good nominal shaped parts. Thermo-mechanical approach using LS-DYNA simulation results were in good agreement with the physical outcome. The presented simulation technique is an efficient tool in evaluating factors related to predicting post-molding warpage.

• Thermo-mechanical homogenization of composite materials

  S. Alameddin, F. Fritzen (University of Stuttgart)

  This work presents a multiscale simulation framework that will be used for the simulation and experimental validation of eigenstresses in composite materials generated via laser-dispersion. These materials are obtained by adding tungsten carbide particles into the melt pool of a base metal to generate surface coatings. Such coatings are used to boost wear-resistance, more precisely to protect metallic surfaces against abrasion, erosion or corrosion. The coating significantly extends the part's lifetime due to the outstanding material characteristics of the locally produced metal matrix composite (MMC). Eigenstresses, which are the residual stresses left in the MMC material after the coating process, shall be investigated and predicted within the framework of this project and their effect on the lifetime shall be estimated.

• Thermomechanical Analysis of the Turbo-Compressor Sliding Bearing Mount Units

  M. Petrushina, S. Klambozki, O. Tchij - UIIP NAS of Belarus

  On SKIF k-1000 supercomputer the temperature fields in turbo-compressor sliding bearings were defined. Dynamic temperature loads were estimated by calculating of heat conduction in the rotor shaft from 600 C heated turbine to the compressor wheel. Conduction and radiation losses were taken into account. The role of friction in heating the contacting parts of the bearing mount assembly was estimated. The calculation of heat conduction through the rotor shaft were made for different exploitation regimes namely for the starting and working regimes and for the lubrication absence conditions. Different constructive shaft variations were used that made it possible to smooth the temperature peaks in thickening ring of the shaft. The temperature fields in bearing mount assembly details were calculated and the thermal stresses were estimated. The role of lubrication was estimated in two ways. In preliminary calculations its influence was estimated by taken into account only its convection and radiation properties as the properties of the environment in the bearing unit. Then the whole process of the oil- bearing unit parts interaction was modeled. The problem was solved in ALE formulation. The gap between rotor shaft and sliding bearing was filled with lubrication. The areas of the ALE- mesh that corresponded to the inflow of the oil was prescribed its initial cool temperature. Then the incoming oil was taken with rotating rotor shaft, the later conducting the heat from the turbine wheel.

• Thin-Walled Beams Research and Development

  Moisey B. Shkolnikov

  An integrated warped FEM beam element has been implemented in LS-DYNA and is considered here as a very important beginning. Accounting for warping is a fundamental part of Thin-walled beam theory, having more than three quarters of century history of research and developments, which are still active. Information related to thin- walled beams looks to be very useful to LS-DYNA users, may define steps for further beam FEM elements implementations and wider usage, and therefore some of the information is presented in this paper. The principal idea of the Thin-walled beam theory to represent three-dimensional thin-walled cylindrical shell structures as one- dimensional thin-walled warping beams was very useful in the past and very important today taking advantage of that beams computational efficiency. So far, however, thin-walled beams are modeled mostly using shell FEM elements, which is computationally more expensive

• Three -Dimensional Integrated Simulation for Composite Sheet Compression Molding

  Jim Hsu, Srikar Vallury, Anthony Yang, Moldex3D Northern America Inc., MI

  Sheet molded composite (SMC) or glass-mat-reinforced thermoplastic (GMT) material is widely used in the automotive industry with the compression molding process to achieve a higher residual length of the glass strands. In this work, an integrated simulation procedure is developed for SMC/GMT composite compression process. First, LS-DYNA® is used to conduct the draping analysis to predict the deformed shape of the initial charge before compression. The deformed shape and other data is then exported to Moldex3D to do the compression molding analysis to get the final part shape and fiber orientation. This work demonstrates a cost-effective analysis tool for sheet composite manufacturing.

• Three Dimensional Analysis of Induced Detonation of Cased Explosive

  Devon Downes, Manouchehr Nejad Ensan (Aerospace Portfolio, National Research Council), Amal Bouamoul (Defence Research & Development Canada–Valcartier)

  Fragments of aluminum impacting on Composition B explosive encased in rolled homogenous armour (RHA) steel were investigated through the LS-DYNA®. The investigation focused on shock to detonation simulations of Composition B, with the objective of determining both the critical velocity which would generate a shockwave strong enough to cause detonation of the explosive, as well as the resulting pressure profile of the detonation wave. Detonation scenarios at low, intermediate and high impact velocities were investigated. It was observed that at low impact velocity the explosive failed to detonate. At intermediate velocities, detonation was due to the development of localized hot spots caused by the compression of the explosive from the initial shockwave. Detonation was also caused by pressure waves reflecting against the casing of the explosive leading to the so-called sympathetic detonation. At high impact velocity, initiation of the explosive was caused by the initial incident pressure wave located immediately behind the top casing/explosive interface.

• Three Point Bending Analysis of a Mobile Phone Using LS-DYNA Explicit Integration Method

  Feixia Pan, Jiansen Zhu, Antti O. Helminen, Ramin Vatanparast - NOKIA Inc.

  In this article, the 3 point bending analysis of a mobile phone using LS-DYNA explicit integration method is discussed. Since there are a large number of contact pairs defined in the FEA model, and the FEA model is very large in a 3 point bending analysis of a phone, it is much more convenient to use the explicit method than the implicit method. However, using explicit procedure to a quasi-static analysis requires some special consideration. Since a quasi-static solution, is by definition, a long-time solution. It often requires an excessive number of small time increments. It is computationally impractical to conduct the simulation in its natural time scale. In real analysis, the quasi-static event is artificially accelerated by two approaches to reduce the computation time. One approach is to use mass scaling. Another approach is to increase the loading rate. These two approaches are closely related and should work together. If they are properly used, the speed of the analysis could be increased substantially without severely degrading the quality of the quasi-static solution. We discuss in this article how the loading rate and mass scaling factor affect each other, how to select proper values of these two parameters, and how to use these two approaches in the 3 point bending analysis of a mobile phone.

• Three-Point Bending Crack Propagation Analysis of Beam Subjected to Eccentric Impact Loading by X-FEM

  T. Tsuda, Y. Ohnishi, R. Ohtagaki (Itochu Techno-Solutions), K. Cho, T. Fujimoto (Kobe University)

  When analyzing a failure or crack propagation problem by FEM, there are the following challenges to solve. (1)It’s necessary to make element boundary match to the failure surface or the crack surface. (2)The failure shape and the crack propagation direction depend on the mesh. (3)It’s necessary to express a singularity of crack tip field.

• Through Process Modelling of Self-Piercing Riveting

  R. Porcaro, A.G. Hanssen, M. Langseth, A. Aalberg - Norwegian University of Science and Technology

  Self-piercing riveting is a relatively new process for joining sheet metals in automotive structures. Information obtained from the riveting process simulation can lead to an improvement in the process design achieving reduction in cost and improvement in the quality of the joint. The process data can also be used to set initial parameters for a 3D simulation of the self-piercing rivet connection under combined tensile and shear loading conditions. Comparison of the results from the 3D simulation with experimental data will give a further proof of the quality of the self-piercing riveting process simulation and a better understanding of the behaviour of the connector. Such information can then lead to an improvement of a numerical model of self-piercing riveted joints using shell elements in crash analysis. In this paper, simulations of the self-piercing riveting process using LS-DYNA are presented. An implicit solution technique with r-adaptivity has been used. The advantages and the limits of using r-adaptivity in this class of metal forming process are discussed. In addition, parametric studies on important parameters for the forming process, i.e. friction, mesh size and failures criteria are presented. Finally, the mapping of data, the 3D simulation of the rivet specimen and the comparison with experimental results are presented.

• Through-Thickness Element Splitting for Simulation of Delamination in Laminated Composite Materials

  Ofir Shor and Reza Vaziri (The University of British Columbia)

  The increasing use of laminated composite materials in advanced industrial applications requires the ability to predict their behavior under the expected service loads. Laminated composite materials exhibit various damage and failure mechanisms, which can cause a degradation of their mechanical properties and lead to catastrophic structural failure. The debonding of adjacent laminate layers, also known as delamination, is considered to be one of the most dominant damage mechanisms in the failure of composite laminates; hence it is important to have numerical analysis tools that are able to predict its initiation and growth. Although methodologies to simulate delamination in composite materials exist, they are limited to small-scale models and are therefore not suitable for large-scale applications of practical significance. A new method is presented here that allows simulation of this type of failure mode in large-scale composite structures. This is achieved by locally and adaptively splitting the structural elements through their thickness, while introducing cohesive zones in regions where delamination has the potential to initiate. The delamination damage can thus propagate in the structure as the simulation progresses. A mechanical benchmark example (Figure 1) is solved using this approach and the results are verified against those obtained using other numerical methods.

• Time and rate dependent constitutive model coupled with nonlocal damage at finite strains for semi-crystalline polymers

  Romain Balieu, Franck Lauro, Bruno Bennani (Univ Lille Nord de France), Tsukatada Mastumoto, Ernesto Mottola (Toyota Motor Europe)

  Many constitutive models were developed in the literature to model the complex behaviour of polymer materials. These models can be sorted in two categories: the physical based models where the microstructure of the material is taken into account for representing the macroscopic behaviour [1,2] and the phenomenological based models where the material discontinuities, in the microstructural scale, are homogenised in a representative volume element. In this way, elasto-plastic constitutive models based on the 3RYHUVWUHVV ́ FRQFHSW 9%2 > @ Xsing the unified state variable theory were extended for polymeric materials [4,5]. The addition of mineral fillers in the semi-crystalline matrix increases the cavitation phenomenon. In this case, the viscoelastic-viscoplastic deformation of the material is accompanied by damage in the form of nucleation, growth and coalescence of cavities. Many damage model were developed for polymer application in order to represent this phenomenon [6,7,8,9]. The damage present in this kind of material induces a softening behaviour which leads to the localisation of the strain in a narrow zone of the structure accompanied by numerical solutions depending of the finite element mesh. The nonlocal model where introduced in the literature in this way, in order to overcome the mesh dependency phenomenon [10,11]. In this work, a non-associated viscoelastic-viscoplastic model coupled with nonlocal damage is developed in order to model a mineral filled semi-crystalline polymer used in the automotive industry. The constitutive equations of the model are stated under finite strain framework by using a hypoelastic formulation. The interesting properties of the logarithmic tensor linking the work conjugate pair Cauchy stress and Henky strain are used in the proposed model. In order to obtain a mesh independent solution with the material exhibiting softening, an integral-type nonlocal damage is developed in this work.

• Tippe Top Simulation by LS-DYNA

  Mitsuhiro Makino - Fujitsu Limited

  The tippe top is a toy consisting of a section of sphere and a short rod. When tippe top, whose rod is at top, is rotating, it automatically inverts and the position of center of mass is raised. This toy is simulated by LS-DYNA.

• Today’s Challenges in Crash Simulation

  Jürgen Kohler, Thomas Frank, Markus Feucht - Daimler AG

  Crashworthiness simulations of car body structures are an important part of the CAE development chain for car design. In recent years, the requirements on passive safety of cars have grown to high standards, leading to a permanent demand on an increase in simulation accuracy. Additionally, demands on fuel efficiency and CO2-reduction are confronting the car body designers with the need of weight reduction to an immense effort. One way to achieve light-weight structures is to replace conventional body-in-white materials, like conventional deep-draw steels, by more sophisticated materials. Besides of using metals such as advanced high strength steel grades, aluminium or magnesium alloys, the use of composite materials and hybrid metal-polymeric structural components is increasing in the automotive industry. Since these materials often show rather complex mechanical behaviour, it is of great importance to precisely predict failure under crash loading conditions. Additionally, especially for metals it seems more and more evident that the before going treatment of the material through the manufacturing process chain significantly influences crash performance of the respective material. Here, an emphasis has been laid on identification of damage parameters and a comparison of relevant damage accumulation models and theories from forming to crash simulation. Special attention was paid to existing differences regarding stress states between forming and crash loading, to clarify differences in failure prediction models respectively. The numerical simulation of structural parts made from plastics is becoming increasingly important nowadays. The fact that almost any structural requirement can be combined in a lightweight, durable and cost effective structure is the driving force behind their widespread application. More and more structurally relevant parts are being constructed and manufactured from plastics. This, on the other hand, drives the demand for reliable and robust methods to design such parts and to predict their structural behaviour sufficiently close to reality. The key ingredients that need to be available are verified, calibrated and validated constitutive models for any family of polymeric materials. This holds true not only for crashworthiness applications – which are the main focus of this contribution - but for any other field of application, too. The application of new materials in body-in-white structures is leading to higher requirements in the joining techniques, too. One example is the conventional spot welding of press hardened steels, where the heat affected zone loses its properties that were achieved by heat treatment. This local change in properties has to be taken into account for a sufficiently precise description of spot weld failure mechanisms. The actual development here is to consider the amount of fracture energy that is dissipated during spot weld failure. This seems to play an important role even regarding the global behaviour of structural parts in full car crash simulations. Finally, it will be shown that for ensuring a maximum in predictive performance, advanced modelling techniques have to be used simultaneously for all topics described above in order to capture possible interactions of the phenomena described above.

• Today’s Challenges in Crash Simulation

  Jürgen Kohler, Thomas Frank, Markus Feucht - Daimler AG

  Crashworthiness simulations of car body structures are an important part of the CAE development chain for car design. In recent years, the requirements on passive safety of cars have grown to high standards, leading to a permanent demand on an increase in simulation accuracy. Additionally, demands on fuel efficiency and CO2-reduction are confronting the car body designers with the need of weight reduction to an immense effort. One way to achieve light-weight structures is to replace conventional body-in-white materials, like conventional deep-draw steels, by more sophisticated materials. Besides of using metals such as advanced high strength steel grades, aluminium or magnesium alloys, the use of composite materials and hybrid metal-polymeric structural components is increasing in the automotive industry. Since these materials often show rather complex mechanical behaviour, it is of great importance to precisely predict failure under crash loading conditions. Additionally, especially for metals it seems more and more evident that the before going treatment of the material through the manufacturing process chain significantly influences crash performance of the respective material. Here, an emphasis has been laid on identification of damage parameters and a comparison of relevant damage accumulation models and theories from forming to crash simulation. Special attention was paid to existing differences regarding stress states between forming and crash loading, to clarify differences in failure prediction models respectively. The numerical simulation of structural parts made from plastics is becoming increasingly important nowadays. The fact that almost any structural requirement can be combined in a lightweight, durable and cost effective structure is the driving force behind their widespread application. More and more structurally relevant parts are being constructed and manufactured from plastics. This, on the other hand, drives the demand for reliable and robust methods to design such parts and to predict their structural behaviour sufficiently close to reality. The key ingredients that need to be available are verified, calibrated and validated constitutive models for any family of polymeric materials. This holds true not only for crashworthiness applications – which are the main focus of this contribution - but for any other field of application, too. The application of new materials in body-in-white structures is leading to higher requirements in the joining techniques, too. One example is the conventional spot welding of press hardened steels, where the heat affected zone loses its properties that were achieved by heat treatment. This local change in properties has to be taken into account for a sufficiently precise description of spot weld failure mechanisms. The actual development here is to consider the amount of fracture energy that is dissipated during spot weld failure. This seems to play an important role even regarding the global behaviour of structural parts in full car crash simulations. Finally, it will be shown that for ensuring a maximum in predictive performance, advanced modelling techniques have to be used simultaneously for all topics described above in order to capture possible interactions of the phenomena described above.

• Tool Cooling Simulation for Hot Forming

  T. Kuroiwa (JSOL)

  Our solution development status on hot forming technique will be reported with a special focus on tool cooling. Hot forming is one of the most promising techniques among which contribute to saving weight of automobiles. Thermal management of blank material is especially important to ensure the hardness of it, since sufficiently rapid cooling of heated blank is needed to cause martensitic transformation. There are two reasons to do a CAE analysis of hot forming, to our knowledge. 1. Save cost in prototyping of tools with pipes for cooling water. 2. Accurate prediction of distribution of martensitic phase. Our goal is to develop designer’s CAE tool of hot forming which predict cooling performance of tools and martensitic phase distribution of blank materials. Simulation of hot forming is a kind of multiphysics problem since it is consist of many physical processes: plastic deformation of blank materials, phase transition of blank, conjugate heat transfer between blank-tool-cooling water, and flow of cooling water. In this paper we limit our scope on tool cooling and present how recent development of LS-DYNA contributes to the performance increase of the simulations.

• Tool Cooling Simulation for Hot Forming II. Experiments and Simulations

  T. Kuroiwa (JSOL)

  To fulfill recent regulations for automobile fuel economy great demand on saving weight of automobiles is growing. Since making a lighter car with conventional material loses occupant safety, at least stiffer materials with the same weight are needed. For example, use of CFRP (Carbon Fiber Reinforced Plastics), Aluminum, Magnesium or Titanium is attracting our attention in these days. But technique to handle these materials is still under developmental stage. High-tensile steels made by hot forming is one of the most promising candidate since it can realize better balance between cost and weight saving. In hot forming technique, heated blank material is pressed by tools and then quenched by various methods to cause martensitic transition of the blank to obtain high tensile steel. It is not only stiff but also has good shape freezing property, causing smaller springback of the stamped materials. As an another advantage of hot forming, steels as raw materials can be easily obtained all over the world, compared with other materials listed above. On the other hand its disadvantages is relatively large investment in plant and equipment such as chiller or cooling tower and costs for prototyping production of tools with pipes to run cooling water. In order to cause the martensitic transition of the blank materials, one needs to quench it sufficiently fast. We, JSOL, think that a CAE tool to calculate and predict the stiffness of high-tensile materials contributes to ensure their strength in mass production stage. Important points in accurate prediction are following: (i) to calculate phase transition of the materials correctly (ii) to predict cooling performance of the tools to ensure (i). By making these uncertainties clear it is expected that CAE is capable of reducing trials-and-errors on prototyping, causing reduction of tool designing costs. LSTC, Dynamore and JSOL have been working on formulating a manufacturing CAE solution to the hot forming techniques. For example, development of phase transition material models (*MAT_244, *MAT_254) will overcome the uncertainty (i) described above. We also have been investigating simulation technique for thermal-structural-fluid coupling calculation to demonstrate the behavior of cooling water flowing in pipes of the tools, corresponding to item (ii) above. In this paper we report the results of recent solution developments on the latter point.

• Tool Design for a High Strength Steel Side Impact Beam with Springback Compensation

  Trevor Dutton - Dutton Simulation Ltd, Richard Edwards, Andy Blowey - Wagon Automotive Ltd

  Prediction of formability for sheet metal pressings has advanced to a high state of confidence in recent years. The major challenge is now to predict springback and, moreover, to assist in the design of tooling to correctly compensate for springback. This is particularly the case for materials now being routinely considered for automotive production, such as aluminium and ultra high strength steels, which are prone to greater degrees of springback than traditional mild steels. This paper presents a case study based on the tool design for an ultra high strength steel side impact beam. The forming and springback simulations, carried out using eta/DYNAFORM (based on the LS-DYNA solver), are reported and compared to measurements from the prototype panels. The analysis parameters used in the simulation are presented, and the sensitivity of the results to variation in physical properties is also reviewed. The process of compensating the tools based on the analysis prediction is described; finally, an automated springback compensation method is also applied and the results compared with the final tool design.

• Topology and Geometry Based Structure Optimization using Implicit Parametric Models1 and LS-OPT

  H.Zimmer, M.Prabhuwaingankar - SFE GmbH, F.Duddeck - Privatdozent

  Today’s vehicle development process demands for quick evaluation of new designs considering the various attributes in the conceptual phase. Various CAx tools and methods are essential to realize these assessments in a very narrow time frame. New design variants with desired criteria should be quickly created and analyzed. Beside NVH behavior and other criteria crash safety needs to be addressed too as early as possible. Synergy in CAE analysis and geometry description is an absolute necessity for a seamless vehicle development process. Where to position beads and how to shape these beads considering the design space and manufacture criteria is a challenging task. Geometry based shape and topology optimization is an enabler for such a seamless vehicle development process. Function driven geometry and geometric requirements based on other criteria are the key factors to determine the design space and the non-design space. Application of realistic load cases based on experience and best practices is a prerequisite for optimization. The geometry based topology and shape optimization offers the necessary flexibility in proposing new design alternatives by modifying the geometry and respecting the manufacturability aspects. This procedure includes more valuable “engineering” information compared to the knowledge of “material distribution” of the standard topology optimization. This paper describes the feasibility of above mentioned seamless vehicle development network where CAE analyses and geometry description go hand in hand. To demonstrate this, optimization of a crash box of a car body structure by inserting and optimizing the position and shape of beads is carried out.

• Topology and Geometry Based Structure Optimization using Implicit Parametric Models1 and LS-OPT

  H.Zimmer, M.Prabhuwaingankar - SFE GmbH, F.Duddeck - Privatdozent

  Today’s vehicle development process demands for quick evaluation of new designs considering the various attributes in the conceptual phase. Various CAx tools and methods are essential to realize these assessments in a very narrow time frame. New design variants with desired criteria should be quickly created and analyzed. Beside NVH behavior and other criteria crash safety needs to be addressed too as early as possible. Synergy in CAE analysis and geometry description is an absolute necessity for a seamless vehicle development process. Where to position beads and how to shape these beads considering the design space and manufacture criteria is a challenging task. Geometry based shape and topology optimization is an enabler for such a seamless vehicle development process. Function driven geometry and geometric requirements based on other criteria are the key factors to determine the design space and the non-design space. Application of realistic load cases based on experience and best practices is a prerequisite for optimization. The geometry based topology and shape optimization offers the necessary flexibility in proposing new design alternatives by modifying the geometry and respecting the manufacturability aspects. This procedure includes more valuable “engineering” information compared to the knowledge of “material distribution” of the standard topology optimization. This paper describes the feasibility of above mentioned seamless vehicle development network where CAE analyses and geometry description go hand in hand. To demonstrate this, optimization of a crash box of a car body structure by inserting and optimizing the position and shape of beads is carried out.

• Topology and Topometry Optimization of Crash Applications with the Equivalent Static Load Method

  Katharina Witowski, Heiner Müllerschön, Andrea Erhart, Peter Schumacher (DYNAmore GmbH)

  This paper deals with topology and topometry optimization of structures under highly nonlinear dynamic loading such as crash using equivalent static loads. The basic idea of the “Equivalent Static Load”- Method (ESL) is to divide the original nonlinear dynamic optimization problem into an iterative “linear optimization ↔ nonlinear analysis” process. The displacement field of the nonlinear dynamic analysis is transformed to equivalent linear static loads for a variety of time steps. This leads to an optimization with multiple linear static load cases. In an outer loop the nonlinear analysis is repeated to correct and adapt the displacement field. There are several previous papers on the idea of equivalent static loads, e.g. Shin MK, Park KJ, Park GJ: Optimization of structures with nonlinear behavior using equivalent load. Comp. Meth. Appl. Math.,196, p.1154-1167, 2007. This paper reports about experiences in the application of the ESL methodology on industrial problems from the automotive industry. For the nonlinear dynamic analysis LS-DYNA® is used, for linear topology and topometry optimization GENESIS from Vanderplaats R&D is applied. The investigations have been performed within a research project, founded by the association BMBF, with several partners from German automotive companies. On the application of the method on large scale problems numerous problems are encountered. Setting up a fully automated and robust process on an HPC cluster with nested linear and nonlinear finite element analysis and optimization for multiple load cases was a challenging task. The general objective of the investigations was to evaluate the suitability of the method for different types of crash and impact problems. The appraisement is with respect to quality and usability of the results and with respect to the numerical costs.

• Topology Design using LS-TaSCTM Version 2 and LS-DYNA

  Willem Roux - Livermore Software Technology Corporation

  This paper gives an overview of LS-TaSC version 2, a topology optimization tool using LS-DYNA for the analysis of nonlinear structural behavior. The focus is on its capabilities, current development directions, and integration into an industrial design environment. Examples of using the new developments such as global constraints, geometric definitions such as symmetry and casting directions, and shells are given.

• Topology optimisation method for crashworthiness design using Hybrid Cellular Automata and thin-walled ground structures

  Stephan Hunkeler, Milan Rayamajhi (Queen Mary University of London), Fabian Duddeck (Technische Universität München)

  Crashworthiness is one of the most demanding design cases for vehicle structures. Until a few years ago, it was mainly addressed using trial and error approaches; but recently, automated structural optimisation for crashworthiness design got more and more popular. So far, most relevant applications use size or shape optimisation. Nevertheless, the ultimate way to achieve significant mass reduction is to use topology optimisation. While topology optimisation for static mechanics is a well established field of research, applications to crashworthiness can be rarely found. Due to high non-linearity of crash simulation, classic topology optimisation methods cannot be applied directly to crashworthiness design. Therefore, alternative methods have been developed. This paper first presents the available methods for topology optimisation in crashworthiness design. A discussion of these methods highlights the opportunity to develop an alternative method which is detailed in the second section of this paper. Then two application examples are presented to showcase the interest and capabilities of this method.

• Topology Optimization for Crash

  K. Witowski, A Erhart, P. Schumacher, H. Müllerschön (DYNAmore GmbH)

  This paper is contributed to the topology optimization of structures under highly nonlinear dynamic loading, e.g. crash. We present our experiences with two software tools: LS-TaSCTM (developed by LSTC, available since 2009, the first version was named LS-OPT/TopologyTM) and Genesis-ESL ® (developed by VR&D) and highlight the possible application areas, capabilities and limitations of the implementations. LS-TaSC nonlinear topology optimization with LS-DYNA can be applied to nonlinear static and dynamic problems. The underlying method is “Hybrid Cellular Automata” (HCA) which is a heuristic, gradient-free approach. The objective is to obtain a structure with uniform internal energy density subject to a given mass fraction. The basic idea of the “Equivalent Static Load”- Method (ESL) is, to divide the original nonlinear dynamic optimization problem into an iterative “linear optimization ↔ nonlinear analysis” process with linear static multiple loading cases for the optimization. The iterative optimization ↔ analysis process is to capture the nonlinearities and the multiple loading cases reflect the nonlinear dynamic deformation progress of the structure within the optimization.

• Topology Optimization for Giga-Casting Design in Automotive Bodies Using LS-TASC & LS-DYNA

  Akshay Kulkarni, Chaithanya Rachayyanavar, Carrie McGowan

  Topology optimization plays a crucial role in generating initial design concepts during the early stages of vehicle development. It is a Finite Element Analysis (FEA) based technique that helps to optimize the shape and distribution of the material in a desired packaging space. This paper explores the application of LS-TaSC and LS-DYNA for topology optimization of giga casting in a vehicle’s underbody. This paper touches on the importance of topology optimization in the design development process and elaborates how the LS-TaSC tool can be used to get directional guidance before initiating detailed design (CAD) work. BIW (Body-in-White) global static bending and torsional stiffness load cases were considered while setting up the optimization model. Various optimization setting parameters, constraints, and post-processing tools available in LS-TaSC were explored and have been elaborated in the paper. The use of LS-TaSC and LS-DYNA in this project enabled the generation of an initial giga casting design concept, indicating the critical areas where material is needed or can be removed. These design concepts were further refined by the design team using CAD tools, considering more realistic manufacturing and performance constraints.

• Topology optimization in crashworthiness design

  Larsgunnar Nilsson - Engineering Research Nordic AB and University of Linköping, Jimmy Forsberg - University of Linköping

  Topology optimization has developed rapidly, primarily with application on linear elastic structures subjected to static loadcases. In its basic form an approximated optimization problem is formulated using analytical or semi-analytical methods in order to perform the sensitivity analysis. When an explicit finite element method is used to solve contact-impact problems, the sensitivities cannot easily be found. Therefore, an alternative formulation for topology optimization is investigated in this work. The fundamental approach is to change the element thicknesses based on the internal energy density distribution in the structure. Within this formulation it is possible to treat nonlinear effects, e.g. contact-impact and plasticity.

• Topology Optimization Methods based on Nonlinear and Dynamic Crash Simulations

  Prof. F. Duddeck, M. Bujny, D. Zeng (TU München)

  Topology optimization for crashworthiness has been investigated during the last years, starting from methods based on linear elastic and static simulations1 or so-called equivalent static loads (ESL) obtained by a single nonlinear crash simulation with a subsequent optimization loop based on the linear stiffness matrix and the corresponding sensitivities2. Both methods do not consider material nonlinearities in their optimization process, which are essential for structural components designed for energy absorption, although it is well-known that plasticity and failure play an important role. As alternative, optimization methods have been proposed, which use fully nonlinear and dynamic crash simulations. The first method, proposed for example in Patel’s PhD thesis, uses a hybrid cellular automata approach (HCA) and derives optimal structures using a homogenized energy density approach where each finite element is modified until the highest degree of homogeneity is achieved3. Because this is not fully appropriate for thin-walled structures, Hunkeler modified the approach (HCATWS – Hybrid Cellular Automata for Thin-walled Structures) such that deformation energy is only homogenized between larger structural entities (i.e. thin walls)4. The most recent method, a combined level set method (LSM) and evolutionary approach, was then proposed by Bujny et al. where more appropriate objectives and constraints can be used with the drawback of higher computational costs5. In this paper, the latest results for HCATWS and LSM will be presented, see also6,7. Special focus is here the investigation of the influence of different material models for plasticity and failure. Examples are, for example, inspired by recent material model development for magnesium alloys with a characteristic anisotropy in the plasticity model8. As a result, it is shown that the optimal topologies depend on the correct material model and that it is necessary to use nonlinear and dynamic finite elements for crash topology optimization. 1

• Topology Optimization of a Stamping Die Structure using LS-DYNA® and LS-TaSC™

  Jithesh Erancheri, Ramesh Venkatesan, Nanda Kumar, Kaizenat Technologies Pvt Ltd

  Cost of Stamping Dies accounts for about 45% of total cost of a vehicle program. The construction cost of these dies is used as benchmark by the automotive companies to evaluate the cost of any new vehicle program and also to determine where they stand compared to their competitions. The cascading effect goes down to the TIER-1 suppliers to optimize their die structure designs in order to stay afloat in the business. FE Simulation tools like LS-DYNA along with optimization tools like LS-TaSC to predict come out with the lighter and optimal die structure designs. In this paper we used LS-DYNA & LS-TaSC to optimize a die structure under loads due to stamping.

• Topology Optimization of a U-Bend Tool using LS-TaSC

  D. Aspenberg (DYNAmore Nordic), N. Asnafi (School of Science & Technology)

  Metal additive manufacturing of stamping tool and die has a potential of reducing the lead time of forming processes, while at least not increasing the cost. As a part of a research project exploring the possibilities to use this type of tool manufacturing techniques, topology optimization using LS-TaSC has been utilized and one example case is presented in this paper, namely a U-bend tool. This paper looks at the possible benefits from using nonlinear simulations in topology optimization, the effect of chosen target mass fraction value, the interpretations needed of optimal results and the effects on the formed specimen after using an optimized tool. Results show that accounting for the time dependent pressure on the tool, rather than applying a form of equivalent static load, gives a different optimal topology. Some manual interpretations of the optimal results are also recommended, as well as studying the effects on the specimen from removing material on the tool side.

• Topology optimization of an automotive hood for multiple load cases and disciplines

  W. Roux, I. Gandikota, W. Roux, G. Yi (Ansys/LST)

  To reduce the head impact injuries in case of traffic accidents, the design of an automotive hood must consider many design requirements including impact of the head against the hood at different locations, be lightweight but with enough stiffness to resist various loads imposed on the hood, and have NVH characteristics such as the fundamental frequency. Methodologies to solve this type of design optimization problem that integrates multiple design criteria are rare to non-existent in the automotive design field. This paper shows how to conduct the worst-case design of the hood for multiple head impact locations, which is required by the pedestrian safety code. In addition, a topology optimization problem of the hood that combines statics, impact, and eigen frequency load cases is solved by using LS-TaSC to provide the optimal lightweight hood structure satisfying the design constraints. This is possibly the first demonstration of both the worst-case design and multi-disciplinary design optimization considering both impact and frequency load cases on an industrial problem.

• Topology Optimization of Transient Nonlinear Structures – A Comparative Assessment of Methods

  E. J. Wehrle, F. Duddeck (Technical University Munich), Y. H. Han (Hyundai Motor Group)

  Topology optimization considering transient nonlinear behavior of mechanical structures, e.g. automotive crash, remains a challenge in both the implementation as well as computational effort. In recent years, efficient optimization algorithms and increased computer technology has begun to allow the development of methodologies to examine optimal topology of structures undergoing such behavior.

• Topometry and Shape Optimization of a Hood

  Y. H. Han (Hyundai Motor Group), K. Witowski, N. Lazarov, K. Anakiev (DYNAmore)

• Towards an Automatic Evaluation of a Car Floor Module in a Pole Crash Load Case

  Verena Diermann, Christoph Boese, Pascal Schlaak, Daimler AG;, Prof. Dr.-Ing. Peter Middendorf, Institute of Aircraft Design, University of Stuttgart

  Nowadays crashworthiness simulations are regarded as not suitable for optimization. One reason is the lack of hard evaluation criteria. A small part of the evaluation of crashworthiness simulations is done by comparing numerical criteria to given boundaries. The larger part of the evaluation consists of visual evaluation based on engineering experience. This visual evaluation on the one hand contains the influence of the engineer’s subjective perception, which endangers the quality and the reproducibility of the overall evaluation. On the other hand, those visual criteria cannot be evaluated automatically and, thus, make the use of them as restriction in a weight optimization impossible. With the example of the full vehicle simulation of the ARENA2036 project lightweight through integrated functions in the pole crash load case, the manual visual evaluation has been analyzed. Therefore, only geometry and displacement of LS-DYNA® d3part files containing the car floor module of several variants have been presented to 45 crashworthiness simulation engineers, who had to evaluate and rank those variants. Based on this analysis, evaluation patterns have been deduced. The possibilities to analyze those patterns automatically, with either an analytical analysis or image analysis, have been checked. The most promising alternative has been implemented, which generates additional numerical output parameters based on the existing LS-DYNA output files. Those parameters have been compared to the feedback given during the manual evaluation, to check to what extent the analysis can be automated and, thus, which criteria can be used as restrictions in a weight optimization based on LS-DYNA models.

• Towards Location Specific Statistical Fracture Prediction in High Pressure Die Castings

  R. Watson, W. Griffiths (Univerity of Birmingham), T. Zeguer (Jaguar Land Rover); S. Ruffle (JVM Castings)

  High pressure die casting is an economical means of producing a high volume of aluminium parts, with a design freedom that can enable lighter structures to be envisioned, compared with wrought assemblies. However, cast aluminium parts have been shown to be vulnerable to damage by defects caused by the entrainment of air during the casting process. A recently developed entrainment prediction algorithm, which is believed to more quantitatively predict the distribution of entrainment defects within a casting, was used to predict the distribution of these defects for two variants of the casting process for a commercial part. Using a novel fuzzy statistical correlation method, the predicted distribution of entrainment damage was correlated with the statistical distribution of entrainment damage, as determined by tensile testing

• Towards the Solution of Cross-Talk in Explicit Isogeometric B-Rep Analysis

  Zeyu Lian, Lukas F. Leidinger, Stefan Hartmann, Frank Bauer, Roland Wüchner

  Driven by the increasing need for seamless integration between Computer-Aided Design (CAD) and Computer-Aided Engineering (CAE), Isogeometric Analysis (IGA) emerged with the groundbreaking research conducted by Hughes et al. [1] in 2005. Unlike standard Finite Element Analysis (FEA) that typically employs 𝐶0-continuous Lagrange polynomials as basis functions, IGA utilizes smooth spline-based basis functions, the same as the ones used to describe the CAD geometries. The usage of consistent basis functions offers the potential to bridge the gap between CAD and CAE.

• Trailing edge failure analysis of a friction pad in a clutch using thermal fluid structure interaction with LS-DYNA® ICFD solver

  A. Nair, I. Caldichoury (Ansys/LST)

  A Clutch is a mechanical link used to transmit torque from engine to transmission and typically rotates at very high RPMs. The clutches continuously engage with friction pads to transmit power for motion and only disengage when a gear ratio change is required. During this process of engaging and disengaging the clutch goes from stationary to moving instantaneously. A combination of friction pads and disks are used to transmit the power. There is a significant increase in temperature due to friction between the pads and plate at transition and during rotation. This temperature increase leads to thermal expansion of parts and can cause uneven shape changes. The deformation leads to increase in frictional energy and eventual rise in heat generation. Friction and temperature along with pressure applied during the high rpm rotation leads to high probability of failure at the leading edge of the pads. Uneven distribution of heat can cause failure in the friction pads. To alleviate the effect of temperature, lubricating oil is injected via channels in the friction pad.

• Transient Dynamic Implicit Analysis for Durability Testing of Bus Seats

  A. Jensen, G. Laird (Predictive Engineering)

  A core challenge to any finite element analysis (FEA) is figuring out loads and how to apply them. For static events, it is usually straightforward. In the case of durability testing, loads are obtained from accelerometers mounted on vehicles that are driven for hours, if not days on test tracks or routes that hopefully replicate the most severe road conditions possible. These accelerations can then be numerically processed and used for various frequency domain analyses such as a random vibration analysis (i.e., PSD), a frequency response analysis, or steady state dynamics. Although powerful and useful, these solution sequences are all based on the linear normal modes response and do not account for the nonlinear evolution of the structure as it shakes, rattles and rolls. As for a nonlinear material response, forget about it. Our approach is to describe how one can take the full acceleration time history and with little sacrifice in accuracy, perform a nonlinear, transient dynamic implicit analysis over a time span of 5 to 10 seconds. The reason for choosing implicit analysis is based on two factors: (i) the necessity for finely detailed meshes in regions of high-stress, and (ii) quick solution times. A series of bus seats was analyzed using this technique and showed good validation against test track data. From a simulation viewpoint, this work could not have been accomplished without the use of the implicit solver since run times were in hours whereas trial explicit runs indicated run times in days on equivalent hardware running with 32 CPU-cores.

• Transient Dynamics of Slicing-Impact Loading on Jet Engine Fan Blades during a Bird-strike Event

  Sunil K. Sinha, Ph.D., Adjunct Faculty, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, 43210-1142

  Based upon numerous field events involving bird-strikes on aircraft propulsion system components, the engine manufacturers have long recognized the need for better understanding and insight in the physics of slicing action for analytically predicting the damage to the fan blade. A medium or large size bird being ingested in a running engine with aircraft velocity in the range of 100-120 m/second, essentially during the take-off time, is capable of doing a catastrophic damage to multiple blades on the fan rotor. The slicing action during oblique impact at the thin leading edge of the metal airfoil can cause non-linear plastic deformation, which is highly transient in nature with peak magnitude becoming large enough to block the airflow to an extent that can result into engine stall. Precise analytical modeling of an actual bird-strike event on a jet engine fan blade is a very difficult and highly challenging problem in the area of transient nonlinear dynamics. LS-DYNA® offers many different options such as Lagrangian bird, SPH bird as well as ALE approach to simulate the dynamic loading on the fan-blade, which is generally localized at the sharp leading edge and peaks usually within 0.1 milliseconds of initial contact. The present paper provides a historical and current perspective from the modeling considerations of fan blade airfoil during the design and development cycle and its implementations in LS-DYNA simulations for accurately determining its dynamic response under bird-strike.

• Transient Fluid Structure Simulation of Ground Vehicles

  Facundo Del Pin, Iñaki Çaldichoury, Rodrigo R. Paz, Chien-Jung Huang (Livermore Software Technology LLC)

  Ground vehicle aerodynamics is an important stage in the design of a car. The field is currently well established, and the final goal is to decrease the lift to drag ratio functional by maintaining certain design constraints. Traditionally the studies are performed in wind tunnels but with the advance of hardware and software in the past two decades most of the design is now performed by simulation using Computational Fluid Dynamics (CFD). The automotive industry has embraced these techniques due to their low cost and high accuracy. But in recent year the tougher environmental regulations together with the natural evolution of technology have pushed the industry into new lighter materials, thinner panels and more compact parts distribution. These changes bring new challenges to the design process. The clay models traditionally used in wind tunnels cannot predict the response of the real structures subject to aerodynamic or thermal loads. Traditional CFD simulations are faced with similar limitations. Furthermore the internal organization of the CAE departments are not catching up fast enough to adapt to this new reality and the result is that last minute unexpected behaviors happen during drive test conditions forcing late modifications and the retooling of parts, greatly increasing the design cost. It is our goal to introduce in the design cycle intermediate steps where coupled Multiphysics simulations will be used to anticipate unexpected behaviors and correct the design before the tooling stage. In this work a real world model of a mid-size sedan is used as a showcase of the different possibilities that are available in LS-DYNA® to perform CFD together with Fluid Structure Interaction (FSI) to study the response of different structural parts of the vehicle subject to aerodynamic loads. One of the main advantages is that complex structural parts are "borrowed" from a LS-DYNA crash model and easily introduced into the CFD model greatly simplifying the process. All the material settings and geometry will be automatically ready for the FSI simulation.

• Transient Response of a Projectile in Gun Launch Simulation Using Lagrangian and ALE Methods

  Ala Tabiei - University of Cincinnati, Mostafiz R. Chowdhury - U.S. Army Research Laboratory

  This paper describes the usefulness of Lagrangian and arbitrary Lagrangian/Eulerian (ALE) methods in simulating the gun launch dynamics of a generic artillery component subjected to launch simulation in an air gun test. Lagrangian and ALE methods are used to simulate the impact mitigation environment in which the kinetic energy of a projectile is absorbed by the crushing of an aluminum honeycomb mitigator. Issues related to the effectiveness of these methods in simulating a high degree of distortion of Aluminum honeycomb mitigator with the commonly used material models (metallic honeycomb and crushable foam) are discussed. Both computational methods lead to the same prediction for the deceleration of the test projectile and are able to simulate the behavior of the projectile. Good agreement between the test results and the predicted projectile response is achieved via the presented models and the methods employed.

• Transitioning From SMP To MPP-DYNA3D For The Simulation Of Large Thermal-structural Implicit Problems

  Dr. Gurdip S. Kalsi (AWE)

  The LS-DYNA family of codes have been used at AWE for many years. For a long time they were used on our shared memory platforms (SMPs) to carry out implicit structural and coupled thermal- structural analyses, amongst others. Over time processor speeds have continually increased and larger memory has become available at reducing costs. This has led to an increase in the size of models as meshes have been refined for better definition and realism of the problems under investigation. However the simulation of the long-term responses of engineering structures poses special difficulties when large models need to be analysed encompassing non-linear behaviours. These non-linearities can arise through sliding interfaces, and more commonly through the complex constitutive responses of non-traditional fabrication materials, such as foams and explosives, that act as structural, load-bearing components. Unlike explicit analysis, in implicit problems the equations cannot be decoupled from each other, and so implicit simulations immediately make large demands on the amount of memory required to solve the problem in-core, and these requirements increase rapidly as the model is refined. For the most complex analyses the turnaround times can grow from weeks to potentially months, as model size increases. This problem is being addressed by re-writing implicit solvers to run in parallel mode on distributed memory platforms (DMPs). Although these developments have helped these codes to reduce turnaround times, work is required to further enhance their scalability. Shared memory and MPI-versions of LS-DYNA have been used at AWE to investigate the transition from SMPs to DMPs for the solution of large, contact-dominated thermal-structural implicit problems. The hybrid version of these codes was also used in some simulations, but this is early work at AWE. This paper reports our findings. It also examines the influence of code characteristics on computing platform requirements. The significant reduction in turnaround time that was realised using MPI instead of the SMP version for a major test problem will be presented, and the scaling characteristics of the MPI and hybrid versions of LS-DYNA for this problem will be shown.

• Transitioning LS-Dyna workloads to the Cloud in the path to Digital Maturity

  I. Fernández (Gompute), D. Dorribo (Gompute)

  Industries worldwide are going through a Digitalization process towards industry 4.0 where cloud resources play a key role, forcing a transition for CAE engineers from traditional, in-house HPC to more flexible solutions in the cloud. On the digital maturity journey there are different dimensions to consider when transitioning a CAE team to the cloud as a permanent solution, being the needs and requirements of the different industries not always covered with a single solution, what requires an analysis of the different layers involved (IT/Network, Licensing, Security, Engineering).

• Transmissionlosssimulation of acoustic elements in LS-DYNA®

  Marko Krebelj (Akrapovič d.d.)

  This paper presents validated simulations of transmission loss in LS-DYNA for basic acoustic elements in exhaust systems. According to [1] there are several indicators available that describe the acoustic performance of an exhaust system and its components. These mainly include transmission loss (TL), insertion loss (IL) and noise reduction (NR). The TL is a ratio of sound power level between the inlet wave entering and the transmitted wave exiting the element. Acoustic element termination has to be anechoic, since the TL is a property of the acoustic element only. The NR is sound pressure level difference across the element. The IL is the loss of sound power from the insertion of an arbitrary acoustic element. In this paper we will focus on the TL only. There are several applicable methods in use to measure the TL. The most common and popular approach for measuring transmission loss is decomposition method or VRPHWLPHV FDOOHG 3WKUHH-pole PHWKRG ́ The method is based on the decomposition theory. The basic idea of the method is that the sound pressure may be decomposed in its incident and reflected waves. When the pressure wave is decomposed, the TL can be calculated. 6RXQG LV RQH RI WKH NH\ WULJJHU HOHPHQWV WKDW PDNH FXVWRPHU ZDQW WR EX\ DQ $NUDSRYLþ H[KDXVW system. Well-done sound solutions have been so far developed with the testing of different exhaust system prototype configurations. This demands time and costs to build and test every new configuration. Therefore, we had been always looking for faster solutions. The goal in our company was to create measurement-validated probational simulation models in LS-DYNA to examine the acoustic performance of such parts. Acoustic component performance prediction is a good example of the use of simulation software in industrial applications. LS-DYNA is one of the widely used finite element codes for solving complex mechanical problems. One of the recent developments is the addition of a vibro-acoustic solver, which enables users to perform a number of vibro-acoustic analyses in the frequency domain. In order to obtain a numerical solution in our case we have used the recently implemented *FREQUENCY_DOMAIN_ACOUSTIC_BEM keyword in LS-DYNA. This new keyword allows users to run acoustic computations based on boundary element method (BEM).

• Trim Curve Development in Forming Simulation

  Pablo Hernandez-Becerro, Xinhai Zhu

  Numerical simulations are increasingly used to design and optimize sheet metal forming manufacturing processes [1]. ANSYS FORMING® [2] offers a comprehensive, process-centric solution for metal stamping simulation. It simplifies the setup of multi-stage forming simulations, making it accessible and efficient for users. Relying on the ANSYS LS-DYNA® multiphysics solver, the platform offers easy job submission and monitoring. The interface integrates post-processing capabilities that allow for detailed analysis of the resulting part.

• Trimmed IGA B-Spline Solids vs. Standard Tetrahedra Finite Elements

  Stefan Hartmann, Lukas Leidinger, Frank Bauer, Dave Benson, Attila Nagy, Liping Li, Marco Pigazzini, Lam Nguyen

  In 2005, Hughes et al. [1] introduced isogeometric analysis (IGA). As opposed to standard Lagrange polynomial-based finite element analysis (FEA), IGA utilizes the same shape functions employed in computer-aided design (CAD) for numerical analysis. In the last decade, the development of IGA in LS-DYNA was mainly focused on thin-walled structures modelled as either structured trimmed or unstructured isogeometric shells. Currently, there is growing interest in the analysis of more complex engineering parts. This requires the use of accurate solid finite elements. It is well known however that rather poor computational performance can be achieved by invoking low-order solid elements. Recently, the potential benefits of volumetric B-spline finite elements have been successfully demonstrated by Meßmer et al. [2], [3]. This led to an increased customer interest and thus to the development of trimmed isogeometric solids in LS-DYNA. This paper provides an overview of basic concepts and current capabilities of trimmed isogeometric solids in LS-DYNA.

• Truck Frame Optimization Considering Crashworthiness, NVH and Static Responses

  H. Dong, J. P. Leiva, B. Watson (OmniQuest), W. Gao, F. Pan (ShareFEA Engineering Technology)

  This paper demonstrates how to efficiently perform optimization for vehicle structures, taking into account nonlinear responses from LS-DYNA crash simulation, as well as responses from linear loading conditions such as NVH and Static. The optimization process is based on the Equivalent Static Load (ESL) method and uses an iterative process which utilizes the non-linear structural analysis results from LS-DYNA and the linear structural analysis and optimization capabilities of GENESIS. With this integration, the combined multidiscipline problem can be solved with only a few LS-DYNA simulations (5 to 10). In addition, large-scale optimization techniques, such as topology, topometry, topography and freeform, can easily be employed. The optimization process and results will be demonstrated using two examples: topology optimization of a beam cross-section under impact and static loading and topometry design of a truck frame under crash, normal modes, and static loading conditions simultaneously.

• Tube Adaptivity for Mesh Fission/Fusion in LS-DYNA®

  Xinhai Zhu, Houfu Fan, Li Zhang, Yuzhong Xiao, Livermore Software Technology Corporation;, NinShu Ma, Osaka University

  A new feature named tube adaptivity for sheet metal forming is implemented in LS-DYNA. It conducts adaptive mesh fission/fusion at the beginning of an adaptive step according to a predefined load path and a set of user defined parameters. Automatically mesh refinement is carried out in the neighborhood of the tool path. Tube adaptivity can help in reducing the computational time of incremental forming or roller hemming while maintain the overall accuracy at the place of interest, which can be considered as a major improvement on the original box adaptivity in LS-DYNA.

• Two Modelling Approaches of Lithium-Ion Pouch Cells for Simulating the Mechanical Behaviour Fast and Detailed

  A. Schmid (TU Graz), A. Schmid (TU Graz)

  For the simulation of the mechanical behaviour of pouch cells, there are varieties of modelling approaches, which differ greatly in the level of detail. In macroscopic models the single plies constituting the cell are not discretized separately, but are homogenized in thickness (pouch cell) or in radial direction (cylindrical cell), respectively. The main advantage of macroscopic models lies in their computational efficiency. However, these models fail in predicting short-circuit on a component-based level. Determination of the component behaviour is only possible to a very limited extent, which means that a component-based short-circuit criterion is also not an option.

• U-splines for Unstructured IGA Meshes in LS-DYNA®

  Dr. Michael Scott, Brigham Young University, Coreform LLC

  The isogeometric analysis (IGA) paradigm [5] eliminates the CAD/CAE data translation problem by using the CAD geometry directly as a basis for analysis. IGA was introduced by Dr. Thomas J.R. Hughes et. all in 2005 (Dr. Hughes is now a senior advisor and co-founder of Coreform), and has produced over 1500 academic papers to date, multiple annual conferences dedicated to IGA, and numerous eye-popping results [7]. In other problems, it gives an accurate answer when FEA gives an inaccurate answer. IGA especially shines in nonlinear structural simulations like contact, highly nonlinear deformations, and fracture, with examples showing dramatic increases in efficiency and robustness over traditional FEA [4, 6].

• Ultra High Power applications designed using the LS-DYNA EMAG solver

  Gilles Mazars, Gilles Avrillaud, Anne-Claire Jeanson, Jean-Paul Cuq-Lelandais (Bmax)

  Bmax offers industrial solutions based on Ultra High Power (UHP) technology and provides manufacturing solutions for Magnetic Pulse (MP) Forming, Welding and Crimping as well as Electro- Hydro-Forming (EHF) processes. The LS-DYNA® Emag solver version 1.7 used in the Eddy’s current approximation allows modelling different parts of the system like coils, workpieces and the dynamic interactions between them. This module is used as an advanced design tool to for example optimize the Lorentz forces generated in the workpiece. To achieve accurate numerical results, many comparisons have been done using Photon Doppler Velocimeter (PDV) measurements implemented in specific test beds. The described case is of a tube crushing. We will also show how LS-OPT® identification and sensitivity capabilities have been used for material identification using the Magnetic Pulse Forming process. The main objective is to characterize the material dynamic behaviour in the strain rate ranges generated by the Bmax processes (around 1000 to 10,000/s). To summarise the LS-DYNA and the LS-PrePost® capabilities greatly aides the engineering team to provide a feasible industrial solutions from tool design to building predictive models to study the feasibility of a project. We can then now respond faster to customer specifications, but also better understand the physical processes and ultimately reduce design costs by limiting the number of physical testing.

• Uncertainty Assessment with Stochastic Simulation in Aircraft Cabin Development

  D. Vogt,R. Hartnack,M. Olbert - EADS Innovation Works, J. Schlattmann, Hamburg University of Technology

  To fulfill the need for shorter development cycles in modern product development the increased use of computer-aided engineering is one possibility. While the numerical calculation of a model leads to one single solution, the behavior of systems in the real world is never exactly repeatable due to tolerances and natural scatter in the system parameters. The assessment of the resulting uncertainties is of great importance for systems requiring a high level of reliability (such as aerospace systems), therefore they should be treated with special care in the development process and in particular in computer-aided engineering. This paper describes the execution and analysis of an uncertainty management technique with Stochastic Simulation for an LS-DYNA model of an exemplary system consisting of an overhead stowage bin and carry-on baggage excited by external acceleration. The Stochastic Simulation results are evaluated using statistical methods. It is shown which parameters are of paramount influence on system behavior and may hence result in a critical load due to carry-on baggage.

• Uncertainty Sources in WorldSID-50M Dummy

  Stefan Kronwitter, Karin Birkefeld, Markus Kösters

  Full vehicle crash tests are never fully identical in terms of their results, even when conducted with the same configuration. This variability arises from the existence of a diverse set of uncertain input parameters, which induces uncertainty in the relevant quantities of interest (QoI). The classical engineering approach, dealing with scattering system behavior and QoI, is to introduce safety factors and thus ensuring the system’s robustness with respect to the adherence of performance-relevant criteria. However, using this strategy within the vehicle safety design process carries the risk that the margins to specific limits might be exceeded in initial hardware tests.

• Undamped Extension of a Nose Landing Gear

  H. Frey (Liebherr Aerospace), W. Lietz, U. Stelzmann (Cadfem)

  In aviation, components are categorized based on the consequences of a failure. This categorization significantly determines the development costs, test quantities and maintenance cost. A simulation can show how serious such a failure can be and thus simplify the classification of the components and finally may reduce costs. This paper describes the simulation of the undamped extension of a nose landing gear of an aircraft. Normally, a hydraulic cylinder is used to extend the landing gear in a controlled manner. The simulation will investigate what happens when this hydraulic cylinder fails completely. Then the landing gear drops down when opening the flaps simply due to its own weight and pushes hard into its end stop. The simulation should show, if afterwards a safe landing is possible.

• Under the Hood of Implicit LS-DYNA

  Cleve Ashcraft, Roger Grimes, Brad Maker - LSTC

• Universal Data Space for Vehicle Development: Managing and Orchestrating Workflows via Policy-driven Data Transfer in Global Enterprises

  Nikhil Mitapalli, Nadine Riske, Christopher Woll, Sebastian Fink

  The car of the future thinks ahead - and, based on the analysis and processing of data, can do far more than humans alone behind the wheel. Radar, lidar sensors as well as cameras, already collect and evaluate large amounts of information in real time and detect hazards such as black ice, objects such as stationary cars or the ends of traffic jams. If desired, the automobile of tomorrow will even drive autonomously. But it will be some time before all offline vehicles have disappeared from the roads and most of all cars are navigating through traffic completely autonomously. A study by the Prognos research institute for the ADAC [1] shows that autonomous driving is not expected to become established until 2040. By the time the first driverless cars are on the roads in Germany, both the volume and variety of data will have exploded. According to estimates by the international market research and consulting firm IDC [2], the volume of data worldwide will grow to as much as 143 Zbytes by 2024. And an end to the flood of data is not in view. In its latest study, IDC forecasts a globally generated data volume of around 284 Zbytes by 2027.

• Unsteady Aerodynamic Analysis around Oscillating Ahmed body by LS-DYNA ver.980

  Hiroyuki Sawamoto Tsuyoshi Yasuki, Hiroshi Tanaka, Kazuyoshi Ishii (Toyota Motor Corporation)

  This paper describes an aerodynamic effect of the Ahmed body model in sinusoidal pitching motion. Relationships of pitching angle to lift coefficient were analyzed by computational fluid dynamics (CFD) of LS-DYNA ver.980. Those numerical results showed good agreements with wind tunnel test results reported in the past. The flow field was investigated by using this numerical analysis result and the relationship of bottom surface pressure distribution to the lift coefficient was clarified.

• Update in dummy model enhancements and effective pre-processing

  Sebastian Stahlschmidt, Alexander Gromer, Reuben D´Souza, Ulrich Franz (DYNAmore GmbH)

  The FAT and PDB dummy models have been developed for more than a decade. The models are used by almost all OEMs and restraint system suppliers to enhance the passive safety performance of their vehicles. Nevertheless, the PDB is still launching new projects to further enhance the predictability of the ES-2, ES-2re, BioRID-II and WorldSID models. This paper presents the current enhancement projects at a glance. With the increasing quality of the dummy and the restraint system models, additional details related to model assembly have a significant influence on the overall accuracy. Thus, a more advanced pre-processing to assemble the finite element input is required. Such pre-processing might involve a sequence of pre-simulations and might take pre-stresses into account. In some cases the computational effort for the pre-processing exceeds the time needed to simulate the final load case. The paper presents ideas and solutions to simplify and to speed-up the pre-processing of the above mentioned dummy models without a loss in accuracy. The solutions utilize standard pre-processing tools and scripts as well as LS-DYNA® implicit and explicit time-stepping schemes.

• Update of a Linear Regression Model to Predict Forming Limit Curves from Tensile Test Data

  G. Trattnig, M. Schmid, H. Pauli, L. Wagner, A. Grünsteidl

  Forming limit curves (FLCs) are widely used for the feasibility analysis of deep drawn steel components and the final tool design. The experimental determination of the FLC is usually based on Nakajima tests, which are evaluated according to the ISO 12004-2 standard with the intersection line method. In recent years the additional determination with the time dependent method [1] is used since it more accurately describes the increased forming potential of modern high ductility steel grades found in practical experiments.

• Update on Resistive Spot Welding Capabilities in LS-DYNA®

  Iñaki Çaldichoury, Pierre L’Eplattenier, Sarah Bateau-Meyer, LSTC, Livermore, USA;, Tobias Loose, DynaWeld GmbH & Co. KG, Germany;, Uwe Reisgen, ISF - Welding and Joining Institute, RWTH - Aachen University, Germany

  Resistance Spot Welding (RSW) is a very important welding process for thin sheet metals with many applications, in particular in the automotive industry. In this method, the contacting metal surfaces are joined by the heat obtained by Joule heating of an electrical current flowing through resistances. These resistances are composed of the bulk resistance of the parts being welded, and of the contact resistances at the interfaces between the electrodes and the sheets, and between the sheets.

• Update on the Electromagnetism Module in LS-DYNA

  P. L'Eplattenier, I. Caldichoury (Livermore Software Technology Corp.)

  An electromagnetism module is being developed in LS-DYNA version 980 for coupled mechanical/thermal/electromagnetic simulations. The physics, numerical methods and capabilities of this module will be introduced. Some examples of industrial applications will be presented. These include magnetic metal forming and welding in different configurations, high pressure generation for equation of state studies and material characterization, induction heating, resistive heating, electromagnetic launchers, magnetic levitation and so forth.

• Updates on trimmed IGA B-Spline Solids

  Stefan Hartmann, Lukas Leidinger, Frank Bauer, Dave Benson, Liping Li, Attila Nagy, Lam Nguyen, Marco Pigazzini

  Recently, trimmed Isogeometric B-Spline solid elements have been introduced in Ansys LS-DYNA ® nonlinear dynamics structural simulation software [1]. The numerical analysis methodology Isogeometric Analysis (IGA) dates to the paper by Hughes et al. [2] in 2005. While in standard Finite Element Analysis (FEA) polynomial basis functions are typically used for the discretization of the geometry and the unknown fields, IGA aims to use the same shape functions employed in the Computer Aided Design (CAD) environment for numerical analysis. This paper reviews the main ideas and concepts of the trimmed IGA B-spline solid finite elements in LS-DYNA and provides an update on the available capabilities. The current modeling workflow for these new element types will be first introduced. Modeling strategies for boundary conditions, contact and connections, and in-core refinement possibilities will be presented, and some recommendations and best practices will be discussed. The potential benefits of this new type of solid finite elements will be illustrated by two numerical examples. The paper closes with a summary and an outlook on future development activities.

• Updates to LSTC's LS-DYNA Anthropomorphic Models

  C. Maurath, S. Guha (LSTC)

  This paper shows the progress of LSTC's LS-DYNA crash test dummy model development effort. It is an update to the presentation and paper “Overview of LSTC’s LS-DYNA ® Anthropomorphic Models”, presented at the 11th International LS-DYNA Users Conference. Updates and details of all released models are presented. The development status of models currently under development is addressed. Outlook to future models is given.

• Usage of fully detailed CAE models for concept design with the ANSA Morphing Tool

  George Korbetis - BETA CAE

  During the concept phase of product development, simplified CAD and CAE models are used to retain model versatility and minimize the set up time and the analysis complexity. However, this process often leads to simplified calculations with inaccurate results diverting from a realistic solution. Additionally, considerable time is spent to convert the simplified CAE models to full detailed ones at a later stage. This paper describes a recommended process for the usage of full detailed CAE models during the concept design phase. The resulting models are ready to run in LS-DYNA and their results are validated. This process is accomplished by the functionality of the ANSA Morphing Tool. The engineer is able to use former versions of full detailed CAE models or even CAE models of similar product versions and transform them according to the new layout within a few work days. Using this process the engineer is able to run the first analysis without the need to add feature details and solver specific entities to the concept model.

• Usage of LS-DYNA in Metal Forming

  M. Fleischer, A. Lipp, J. Meinhardt, P. Hippchen, I. Heinle, A. Ickes, T. Senner (BMW Group)

• Usage of LS-DYNA in the Development of Professional Hammer Drills

  A. Syma - Black & Decker GmbH, M. Hörmann - CADFEM GmbH

  The development of modern electric power tools for professional use requires special attention. Characteristic aspects such as efficiency and user comfort along with robustness and durability are always of importance to the manufacturer. For the fulfillment of these attributes computer-aided simulation combined with the finite element software LS-DYNA® is a central point during the development process at Black & Decker GmbH, i.e. from the predevelopment phase up to testing near series prototypes. The area of application of LS-DYNA® is not limited to classical drop test cases for devices (see Figure 1), but goes far beyond that. DeWALT uses LS-DYNA® for their hammer drill development in order to account for different hammer sub-assemblies and various structural mechanical concerns. Particularly during the hammer work interpretation regarding unwanted idle impacts, LS-DYNA® can simulate harmful shock waves in the drilling spindle and tool holder for the equipment. Further LS-DYNA® allows the computational illustration of the entire hammer drive train (see Fig. 2) as well as the simulation of comprehensive misuse. Based on case examples from the daily employment of LS-DYNA® in development practice the various types of applications at Black & Decker GmbH, DeWALT are shown.

• Usage of LSTC_NCAC Hybrid III 50th Dummy in Frontal Occupant Simulation

  Ming-Pei Lin, Chih-Min Chang, Cho-Hsuan, Tsai, Chia-Hui Tai, Chun-Te Lee (HAITEC)

  Occupant simulation is very useful for vehicle restraint system and passive safety development. Since the requirements of safety assessment are more and more demanding, the occupant simulation models have to be more and more accurate. Dummy model is very crucial in occupant simulation, and is difficult for most vehicle manufacturer to build. To purchase a commercial dummy model is a very reasonable and safe choice. Alternatively, LSTC offers LSTC dummy models, which are free for LS-DYNA® users. It is foreseeable that LSTC dummy models may not be as stable as commercial ones. This article describes the usage of LSTC_NCAC Hybrid III 50th dummy in frontal occupant simulation, and try to give a preliminary guideline of usage in vehicle development.

• Use of Data Reduction Methods for Robust Optimization

  Dominik Borsotto, Lennart Jansen, Robin Strickstrock, Clemens-August Thole (SIDACT GmbH)

  Data reduction methods like principle component analysis, singular value decomposition and independent component analysis methods allow analyzing huge sets of data. Applied to simulation results they allow the characterization of major trends in the variation of these results. For the public Chevrolet Silverado example all thicknesses are initially varied independent of each other among a number of simulation results and its correlations are computed to the variation of the behavior of the firewall. The behavior of the firewall is approximated using data reduction methods. It turns out, that the variation of the firewall can be characterized by one basic deformation mode. The thickness variation of a part may show strong or weak correlation to the behavior of this deformation mode. In several steps now, the sensitivity analysis is repeated using only those parts for thickness variation, which had a strong correlation in the previous step. Finally it turns out, that the thicknesses of the longitudinal rails as well as certain bifurcation behavior of the longitudinal are responsible for this variation mode of the firewall.

• Use of Forming Limit Curve as a Failure Criterion in Maritime Crash Analysis

  B. Atli-Veltin, L. Vredeveldt (TNO)

  The crashworthiness of marine structures is one of the main area of interest of several parties active in maritime area. The ability of structural material to absorb mechanical energy without fracture, is a very important safety feature. For offshore structures, the general approach towards a fracture criterion is based on the Norsok standards. For inland waterways, it is based on ADN Guidelines.

• Use of LS-DYNA for Structural Fire Engineering

  G. Flint, E. Rackauskaite, A. Maani, A. Temple, P. Kotsovinos (Arup)

  Structural response in fire is complex and can only be properly investigated using finite element analysis considering non-linear geometry and material properties. Full scale fire testing to investigate the real response of structural forms to severe fires represents significant risks to researchers and is also expensive and difficult to undertake effectively. Therefore, computational tools are necessary for the safe design of structures under fire conditions. The majority of the computational tools currently used for structural fire analyses use static solvers. Explicit dynamic solvers such as in LS-DYNA are rarely used even though they are capable of dealing with highly non-linear problems.

• USE OF LS-DYNA SHELL ELEMENTS IN THE ANALYSIS OF COMPOSITE PLATES WITH UNBALANCED AND UNSYMMETRIC LAYUPS

  Saiphon Charoenphan, Lawrence C. Bank, Michael E. Plesha - University of Wisconsin-Madison

  In order to obtain the desired coupling between deformation modes that can occur in composite material plates having unbalanced and/or unsymmetric lamination schemes, the appropriate shell element formulation must be selected from the available formulations in LS- DYNA. An investigative study was conducted to determine which of the shell element formulations in LS-DYNA 950 can be used for modeling such plates prior to performing in- depth studies on the behavior of more complex composite material structures. Unbalanced/symmetric and balanced/unsymmetric lamination schemes were studied for single-element and four-element “patch” tests. The elastic response of these models to in- plane tensile loads and out-of-plane bending loading was investigated. The shell elements were used with material model 54 (MAT_ENHANCED_COMPOSITE_DAMAGE). The study focused on determining which of the shell element formulations would produce the expected coupling between deformation modes. The Belytschko-Leviathan shell formulation was found to be the best choice for coupled elastic response. Progressive failures of laminates under in-plane tensile and compressive loads were also investigated using this element formulation.

• Use of LS-DYNA to Assess the Energy Absorption Performance of a Shell-Based KevlarTM/Epoxy Composite Honeycomb

  Michael Polanco - NASA Langley Research Center

  The forward and vertical impact stability of a composite honeycomb Deployable Energy Absorber (DEA) was evaluated during a full-scale crash test of an MD-500 helicopter at NASA Langley’s Landing and Impact Research Facility. The lower skin of the helicopter was retrofitted with DEA components to protect the airframe subfloor upon impact and to mitigate loads transmitted to Anthropomorphic Test Device (ATD) occupants. To facilitate the design of the DEA for this test, an analytical study was conducted using LS-DYNA®* to evaluate the performance of a shell-based DEA incorporating different angular cell orientations as well as simultaneous vertical and forward impact conditions. By conducting this study, guidance was provided in obtaining an optimum design for the DEA that would dissipate the kinetic energy of the airframe while maintaining forward and vertical impact stability.

• USE OF MPP-DYNA FOR SIMULATING SHEET METAL FORMING PROCESSES

  P. Christopher Galbraith, Dylan N. Thomas - Medusa Computing Corporation

  Sheet forming simulations have been shown to have a profound impact on the tool and die industry, but accurate solutions for large panels often require large amounts of CPU time. The development of MPP-DYNA has allowed a large number of CPUs to be applied to a single problem thus reducing total elapsed time. This paper discusses the use of MPP-DYNA for obtaining accurate solutions in small amounts of elapsed time using inexpensive PC-based clusters of computers

• Use of Prepreg Carbon and Aluminum in Satellite Shielding Submitted to High Velocity Impacts

  Tess LEGAUD, Morgan LE GARREC, Vincent LAPOUJADE (Dynas +), Hakim ABDULHAMID, Paul DECONINCK (Thiot Ingénierie)

  A substantial number of debris coming from human production gravitates around the Earth. Their size, nature, orbit and velocity can extremely vary, but all these debris represent an increasing collision risk and a threat for the current and future spatial activity. The spatial researchers are looking for solutions to limit this risk, by better controlling the launched objects number and by improving the protection of their structures. All those debris are classified depending on their size. The ReVuS European project showed that the most dangerous debris, according to the satellite mission failure probability, have a diameter included in the range 1mm to 5mm. Following this reference, the aim of the ATIHS project, funded by French region Occitanie, is to improve the satellite protection from millimetric debris impacts. Multiple solutions exist in order to do so, ATIHS focuses on the shielding one. The project global aim consists in: - Improving the satellites resistance on strategic locations to prevent it from the mission failure, - Working on the secondary debris generation limitation during a non-lethal impact in order to minimize the satellite contribution in the debris increasement. The project is composed of three main tasks: - Evaluating new material solutions showing an optimised mass/resistance combination, - Evaluating new hypervelocity testing devices which should permit to go further than the currently available devices (goal: 8 to 12 km/s for millimetric to centimetric projectiles), - Setting up numerical methodologies that should permit to increase the capacities and the hypervelocity computations reliability, by accurately modelling the materials behaviour during this kind of extreme solicitations. This article focuses on the hypervelocity impact response. It especially deals with the evaluation of new structures composed of carbon prepreg or/and zylon laminates to better protect the satellite equipment and there SPH modelling methodologies. As a first step, some tests have been performed on a unique sheet made of composite (carbon prepreg or zylon). Then, it is used to compose a mixed Whipple shield such as the assembly of two skins using various materials.

• Use of Simpleware Software for LS-DYNA® Analyses

  Brian Walker, Rajab Said - Arup, Philippe Young - Simpleware Ltd

  Simpleware have developed a suite of programs that are used to convert imaging data obtained from CT, microCT, MRI or Ultrasound scanning equipment into finite element meshes for use in LS-DYNA. Simpleware provides what is effectively a 3D photocopier: three dimensional replicas can be generated automatically based on scans. In parallel, computer simulations can be used to assess the suitability or performance of objects in operation. Simpleware's technology has opened up FEA and RP manufacturing to a variety of applications and research fields including: • Industrial reverse engineering • Research in materials and composites • Non-destructive evaluation (NDE) • Biomechanical Research • Implant design and manufacturing • Surgery simulation and planning • Forensics • Biomimicry • Archeology ScanIP is used to import 3D imaging data from MRI, CT, Micro CT and Ultrasound scans. It provides a series of image processing and segmentation tools which allow the user to define areas of interest in the image based on grey scale values. The smoothing algorithms used by ScanIP are volume, topology and geometry preserving. This ensures the accuracy of both the generated surface reconstructions and mesh models is based on image accuracy alone. The segmented areas can then be exported as a 3D stereo lithography file or exported into +ScanFE for meshing. The stereo lithography files can either be used directly for producing rapid prototype parts or imported into CAD software. + ScanCAD allows you to import a CAD model, position it interactively within the 3D imaging data and then generate a Scan IP mask. Scan CAD can be used to obtain patient specific models by positioning CAD models of different implants within a pre-operative scan. Post-operative performance can be simulated using the combined models and multiple scenarios can be tested easily. The paper describes the software and illustrates its use in different fields of application.

• USE OF STOCHASTIC ANALYSIS FOR FMVSS210 SIMULATION READINESS FOR CORRELATION TO HARDWARE TESTING

  Amit Sharma, Ashok Deshpande, Raviraj Nayak - General Motors Corporation

  The FMVSS210 regulation establishes requirements for seat belt assembly anchorage. The Federal government mandate requires use of Pelvic and Torso Body Blocks for testing belt anchor strengths for lap and shoulder belts respectively. The belt anchorages are to be designed to withstand loads of 13.34 kN if both lap and shoulder belts are used and 22.24 kN if only lap belts are used. The analytical simulation of the hardware test is done using LS- DYNA. Hardware testing is of quasi-static nature while the simulation uses the dynamic code. However the analysis could be made to approach the quasi-static test by adjusting some input parameters in the simulation. In addition, some input parameters need adjustment for making the model more robust and to make it correlate with the hardware test. This study involves the use of Optimal Symmetric Latin Hypercube Design to explore the design space, and to develop a fast surface response model. This response model can be viewed as a surrogate model to the actual LS- DYNA simulation. This response model is used to rank the input parameters by its percent contribution towards the variation of the output responses. After determining the fit of the response model, it is used to perform the stochastic simulation. The confidence interval for test correlation prediction can then be estimated. This technique can further be used for design sensitivity studies and for improving the vehicle structure with respect to FMVSS210 regulation.

• Use of the Combustion and Stochastic Water Spray Modules in the LS-DYNA Compressible Flow Solver

  K.-S. Im, Z.-C. Zhang, G. Cook, Jr (LSTC)

  Recent development of the chemistry and stochastic water spray modules in the CESE LS-DYNA® compressible flow solver will be reported in this presentation. For the chemistry, detailed descriptions about CHEMKIN input files including the thermodynamics and transport data files will be presented. How to construct of the keyword files is also demonstrated for the various chemically reactive flows. Limitations of the current chemistry module and future development with reduced chemistry will be discussed. For the stochastic water spray, the concept of the stochastic particle, breakup models such as the TAB and KH&RT hybrid models, and collision models are described and corresponding keyword setups are explained with water spray flows. Limitation and current developments including fuel vaporization models will be also presented.

• Use of the FTSS Modular Crash Dummy Models in Frontal Occupant Simulation

  Richard Brown - Jaguar Land Rover

  Legal and consumer crash tests use crash dummies as the key measurement device in the assessment of crash severity. The dummies are complex assemblies in themselves, and sophisticated DYNA FE models are available, with a significant amount of validation testing to support them. In a large vehicle crash model, the dummy is typically responsible for 10-20% of the CPU time, and there is no strong motivation to reduce its size; in fact, the tendency is to make the dummy models more complex, and the latest versions have undergone a significant refinement, which has increased the CPU time needed to run the dummy on its own by a factor of 2. If the size of the vehicle crash model is reduced, however, the proportion of CPU time taken by the dummy increases, and can constitute 90% of the total. Recent developments in the use of DYNA for frontal occupant modelling at Jaguar Land Rover require a significant reduction in overall run-time, and the standard full dummy models impose a limit on the reduction that can be achieved. For this reason, simpler dummy models have been created by FTSS, which allow the selection of the full, sophisticated representation, where maximum fidelity of measurement is necessary, but provide a simpler model, where this is adequate. The model is constructed using a modular structure, allowing any combination of complex and simple dummy parts to be assembled, and ensuring that geometry, joint configurations and output references are maintained. A set of component validation comparisons has been made at FTSS and Jaguar Land Rover between the simple and complex models, to demonstrate the degree of approximation inherent in the new models. Additionally, a comparison has been made in vehicle sled models to demonstrate the usefulness of the approach. The CPU requirement has been compared, using a number of configurations of dummy and vehicle models. The validation results show that the simple models are a valid representation of the dummy in areas where the detail of the local behaviour is not required. In many areas the simple model can also provide adequate dummy measurements. There is scope for further development of the simple dummy parts, but the modular nature allows current limitations to be avoided, through the use of the fine model, where the application requires it. The CPU demands of the dummy model can be significantly reduced, allowing the demands of the smaller vehicle crash models to be met. Additionally, the criteria for usability, such as maintenance of geometry, and of positioning configuration are fulfilled.

• Use of the FTSS Modular Crash Dummy Models in Frontal Occupant Simulation

  Richard Brown - Jaguar Land Rover

  Legal and consumer crash tests use crash dummies as the key measurement device in the assessment of crash severity. The dummies are complex assemblies in themselves, and sophisticated DYNA FE models are available, with a significant amount of validation testing to support them. In a large vehicle crash model, the dummy is typically responsible for 10-20% of the CPU time, and there is no strong motivation to reduce its size; in fact, the tendency is to make the dummy models more complex, and the latest versions have undergone a significant refinement, which has increased the CPU time needed to run the dummy on its own by a factor of 2. If the size of the vehicle crash model is reduced, however, the proportion of CPU time taken by the dummy increases, and can constitute 90% of the total. Recent developments in the use of DYNA for frontal occupant modelling at Jaguar Land Rover require a significant reduction in overall run-time, and the standard full dummy models impose a limit on the reduction that can be achieved. For this reason, simpler dummy models have been created by FTSS, which allow the selection of the full, sophisticated representation, where maximum fidelity of measurement is necessary, but provide a simpler model, where this is adequate. The model is constructed using a modular structure, allowing any combination of complex and simple dummy parts to be assembled, and ensuring that geometry, joint configurations and output references are maintained. A set of component validation comparisons has been made at FTSS and Jaguar Land Rover between the simple and complex models, to demonstrate the degree of approximation inherent in the new models. Additionally, a comparison has been made in vehicle sled models to demonstrate the usefulness of the approach. The CPU requirement has been compared, using a number of configurations of dummy and vehicle models. The validation results show that the simple models are a valid representation of the dummy in areas where the detail of the local behaviour is not required. In many areas the simple model can also provide adequate dummy measurements. There is scope for further development of the simple dummy parts, but the modular nature allows current limitations to be avoided, through the use of the fine model, where the application requires it. The CPU demands of the dummy model can be significantly reduced, allowing the demands of the smaller vehicle crash models to be met. Additionally, the criteria for usability, such as maintenance of geometry, and of positioning configuration are fulfilled.

• User-Defined Nonlocal Models in LS-DYNA

  F.X.C. Andrade, J.M.A. Cesar de Sa , F.M. Andrade Pires - University of Porto, M. Vogler - Leibniz Universität Hannover

  In this paper, we present an implementation technique that aims to easily incor- porate the benefits of a nonlocal formulation to existing local constitutive models. In order to avoid pathological mesh dependency, an approximation of the nonlocal strategy is adopted. The technique is designed in such manner that the nonlocal extension of previously existing local models is carried out straightforwardly, requiring only minor modifications in the local routines. The implementation in LS-DYNA is depicted in detail for which a FORTRAN code excerpt is provided. In order to validate the proposed nonlocal scheme, we have considered two different constitutive models: one of them intended for the description of ductile materials, the other one suitable for the simulation of fiber-reinforced composites. The numerical analysis of different specimens shows that the proposed nonlocal strategy is able to eliminate spurious mesh dependency under different stress states and using different material models.

• USGA Rule 4-1e Optimization of a Golf Driver Head Using LS-DYNA and Altair HyperStudy®

  Tom Mase - Michigan State University, Eric Nelson, Jeff Brennan - Altair Engineering, Bruce Pettibone - Independent Consultant

  A simulation of USGA’s test procedure for Rule 4-1e was optimized using 3 shape and 10 size design variables. The optimized solution increased the coefficient of restitution from 0.845 to 0.917 while maintaining stresses below 150 ksi and club head mass at 200 g.

• Using *MAT_213 and *MAT_187 to Predict Failure in Unidirectional Composites

  Bilal Khaled, Loukham Shyamsunder, Josh Robbins, Yatin Parakhiya, Subramaniam D. Rajan (Arizona State University)

  Failure in composite materials is due to various complex mechanisms often occurring simultaneously. The heterogeneous, anisotropic nature of composites provides challenges in deriving analytical models for failure similar to what has historically been done with homogeneous, isotropic metals. However, as composites continue to be used in the design of large structures, finite element material models which homogenize the composite response become the only logical choice as modeling the entire microstructure is currently impractical. Thus, relating the microscale behavior caused by the macroscopic excitations is required. A modeling methodology where plasticity, damage, and failure related experimental data are obtained for each constituent and subsequently used to generate high fidelity computational micromechanical models. The ultimate goal is to utilize information from the micromechanical computational models to drive the failure sub-model of *MAT_213 in LS-DYNA®. The first step is to obtain high fidelity experimental data and refine the respective material models for each constituent. This research presents the experimental results from tests performed on the F3900 epoxy resin. The data is then used to populate the input deck for *MAT_187 in LS-DYNA. Verifications tests are presented showing how the derived experimental data performed in virtual finite element tests.

• Using a Rolls-Royce representative engine model to evaluate scalability of LS-DYNA thermal solvers

  G. Blankenhorn, J. Wang, R. Grimes, F.-H. Rouet (LSTC), J. Ong (Rolls-Royce)

  In the Finite Element Modeling community there is a trend to use models with increasing modeling details which raises the numbers of elements and solution variables. The increase in solution variables has a big impact on the run time of the analysis. Reducing wall clock time is an important item in using numerical analysis in production. The wall clock time can be reduced by using improved CPU technology and hardware with a higher throughput and lower latency for memory, storage and interconnect. On the software side, the use of parallel models to utilize more cores in an analysis reduces the wall clock time. Key measure for reducing wall clock time is scalability, which is in general expressed as the reduction of the run time due to an increase of cores used for the analysis. LSTC is currently offering LS-DYNA in three different parallel models, namely shared memory parallel (SMP), massive parallel processor (MPP) and the combination of both models (HYBRID). The focus on these developments is scalability for all three parallel models. Scalability is influenced by several factors. Beside the already mentioned hardware environment, main contributors are the decomposition (MPP and HYBRID) of the model, the model size and application type. Scalability can not only be evaluated on a global implementation level. It needs to be evaluated on the application at hand and the features utilized in this analysis. This contribution discusses the scalability of thermal solvers offered by LS-DYNA MPP using a surrogate engine model from Rolls-Royce. Three thermal solver types are used with three different MPP rank count (4, 8 and 16). The scalability is measured using the wall clock time summary of the LS-DYNA runs found in the d3hsp files.

• USING CAE TO EVALUATE STRUCTURAL FOAM ALTERNATIVES IN B-PILLAR AND BUMPER DESIGNS

  Sameer Gupta - Honda R&D, Americas, Inc.

  This study examined the viability of using structural foam designs as lightweight alternative in B-pillar and bumper designs. The B-pillar was evaluated for side impact performance with respect to intrusion, while the rear bumper was evaluated for low speed impact performance with respect to intrusion and energy absorption. Typical stamped steel structures were used as baselines. Structural foam designs were evaluated using simulation and iterated until similar performance was achieved. Simulation results showed that the final design iteration of both the B-pillar and rear bumper achieved performance equivalent to the baseline with the benefit of reduced weight.

• Using CAE to evalute a structural foam design for increasing roof strength

  Sameer Gupta - Honda R&D

  In recent years, there has been increased discussion of the strength of vehicle roofs in rollover crashes. NHTSA recently revised the federal roof strength requirement and the IIHS has published an even more stringent roof strength goal. While working to increase roof strength, automakers are also working to reduce vehicle mass for improved fuel economy and other benefits. Developing technology to achieve both of these goals is challenging. This paper investigates the use of CAE to evaluate the addition of structural foam to an existing design to maintain or increase roof strength. A concept solution that combines nylon and structural foam material was developed and analyzed using an explicit finite element model and later tested on a body-in-white to evaluate the CAE predictions. The main evaluation method was the FMVSS 216 test procedure. Through CAE analysis and actual testing, the modifications were found to have increased roof strength. A performance target was set and a conceptual steel-only assembly was created in CAE to meet this target. The foam/steel assembly met the performance target but at a reduced weight compared to the steel-only assembly. These analyses demonstrated that CAE is useful for predicting the performance of foam/steel assemblies and that foam/steel assemblies can yield greater strength with lower mass than a steel-only assembly. Questions regarding field performance and the feasibility of mass-production must still be addressed.

• Using Cloud Computing to Reduce Simulation Turnaround Times and Increase Simulation Throughput

  S. Yang (IMMA), A. Dittmer (Pengium Computing)

  FEA simulation throughput directly impacts productivity in any engineering organization that uses computational simulations in their design workflows. In the typically iterative design process, higher simulation throughput and shorter turnaround times allow for exploring more design parameters which in turn results in product designs that are closer to the elusive ‘optimal’ solution. On the other hand, the limited availability of computational resources often limits simulation throughput and increases the turnaround time for simulations resulting in less optimal solutions or delayed schedules. Offering scalability and a pay-as-you go payment model cloud computing promises a way out of this dilemma. This paper provides an overview of Penguin Computing’s public cloud infrastructure Penguin on Demand (POD) including a discussion of POD’s security model. The paper then discusses how IMMI, a provider of advanced safety systems reduced job turnaround time and increased job throughput of LS-DYNA simulations, using a hybrid model of in-house compute resources and Penguin Computing’s public cloud offering Penguin Computing on Demand (POD). Specific examples such as design of IMMI’s FlexSeat, a three point belted seat for school buses, frontal crashing simulation of fire trucks as well as respective benchmark data will be provided.

• Using Data from Physical Experiments to Train Machine Learning Material Models

  Daniel Sommer, Pauline B¨ohringer, Markus Stoll, Peter Middendorf

  Structural analysis of mechanical components, such as predicting the deformation behavior of sheet metal or assessing the crash safety of a vehicle, typically relies on finite element analysis (FEA). One critical aspect influencing the quality of these simulations are the material models that describe the relationship between strains and stresses. However, the development and selection of the most appropriate models is a significant challenge that involves costly and time-consuming testing and calibration procedures.

• Using history variables in materials to reduce modelling effort and increase model accuracy

  M. Styrnik (BMW Group), T. Erhart (DYNAmore)

  In crashworthiness simulation the definition of material properties is one of the key aspects to obtain reasonable results. However, a lot of materials come with properties that either change locally or are generally of stochastic nature. Additionally, production processes (e.g., welding) might change the behavior of certain materials. To overcome the necessity of defining an individual part for each region where material properties differ a new approach was developed. With the new keyword *DEFINE_TABLE_COMPACT it is now possible to define material properties by means of a multi-dimensional table with arbitrary variables controlling for example the plastic flow curve or the damage behavior. Secondly, the keyword *INITIAL_HISTORY_NODE enables the user to set these variables individually on each node in the model. This presentation shows possible applications of this approach and the benefits on parametric modelling and simulation.

• Using JFOLD & LS-DYNA to Study the Effects of Folding on Airbag Deployment

  R. Taylor (Arup), S. Hayashi (JSOL)

  Today's engineers and designers need accurately folded airbags in their deployment simulations. Minor changes in the way the airbag is folded can cause different deployment behaviour, which can lead to trim fracture, hang-ups and unintended injury. There is a growing demand for robust, accurate analysis to study and mitigate these problems, but creating an accurate model of a folded airbag is still a challenge. JFOLD is a software tool developed to meet the growing demand for fast and easy simulation based airbag folding.

• Using JFOLD and LS-DYNA to Study the Effects of Passenger Airbag Folding on Occupant Injury

  R. Taylor (Arup), S. Hayashi, M. Murase (JSOL)

  JFOLD is a software tool for simulation-based airbag folding in LS-DYNA®. This paper presents how JFOLD and LS-DYNA can be used effectively to research how slight changes in automotive passenger airbag folding can lead to significant changes in occupant injury prediction. The demands placed on today’s occupant safety teams continue to increase, driving up the need for airbag complexity and simulation accuracy whist driving down the time to deliver. Accurate airbag simulation is critical to improve occupant safety in an increasing number of crash scenarios and out-of-position cases, including passengers of autonomous vehicles. In addition, airbag simulation is now being used to assess the performance of interior trim components during early break-out and deployment.

• Using LoCo for Multi Run Simulations

  R. Luijkx (AUDI), M.Thiele (SCALE)

  For several years now AUDI and DYNAmore (now SCALE) have been working on a new generation of SDM-System called LoadcaseComposer, Short: LoCo. This SDM-System applies several new approaches to Simulation Data Management, such as strict offline capabilities with permanent synchronization of relevant data, consequent and strict version management of all related objects of simulations, novel ontology based approaches for the assembly of components as well as easy customizability and supporting a sustainable process by means of a “continuous integration” approach for frequent upgrades of the entire LoCo deployment.

• Using LS-Dyna as an Aid to the Inclusive Design of Child Resistant Closures

  Joe Luxmoore, Dr. Alaster Yoxall - University of Sheffield

  The population of most developed countries is ageing. Despite continuing medical advances, ageing brings with it a host of issues, not least a loss in strength and dexterity. One major area of concern is the ability of elderly consumers to access packaged goods such as food and medicines. In previous studies, the authors developed an LS-Dyna model of a human hand that was used to investigate the effect of physical dimensions and the choice of grip type on joint stresses and hence levels of discomfort. The work was supported by consumer ethnography studies and lead to recommendations for inclusive packaging design. In the present paper, the model is applied to a product that is known to cause particular difficulties for the elderly, the “squeeze and turn” child resistant closure, identifying the specific ergonomic issues associated with it.

• Using LS-Dyna for Hot Stamping

  Arthur B. Shapiro - LSTC

  Presented is a methodology for finite element modeling of the continuous press hardening of car components using ultra high strength steel. The Numisheet 2008 benchmark problem BM03 [1] is selected as the model problem to be solved. LS-DYNA [2] has several features that are useful to numerically model hot sheet metal stamping, such as: (1) modeling high rate dynamics for press forming; (2) conduction, convection and radiation heat transfer; (3) tool-to-part contact conductance as a function of interface pressure; (4) material models that account for temperature dependent properties, phase change, phase fractions, and Vickers hardness prediction; and (5) a CFD solver for tool cooling.

• Using LS-Dyna for Hot Stamping

  Arthur B. Shapiro - LSTC

  Presented is a methodology for finite element modeling of the continuous press hardening of car components using ultra high strength steel. The Numisheet 2008 benchmark problem BM03 [1] is selected as the model problem to be solved. LS-DYNA [2] has several features that are useful to numerically model hot sheet metal stamping, such as: (1) modeling high rate dynamics for press forming; (2) conduction, convection and radiation heat transfer; (3) tool-to-part contact conductance as a function of interface pressure; (4) material models that account for temperature dependent properties, phase change, phase fractions, and Vickers hardness prediction; and (5) a CFD solver for tool cooling.

• Using LS-DYNA Implicit for Metal Forming Applications

  Cleve Ashcraft, Roger Grimes, Xinhai Zhu - LSTC

• Using LS-DYNA MM-ALE capabilities to help design a wall mitigating accidental blast effects

  Julien Lacambre, Laurent Delmas - Alyotech TS&I

  A solution had to be found in order to protect buildings neighboring an industrial site from the blast effects of possible accidental explosions on the site. One of the main issues was that the point of detonation would occur relatively close to the endangered buildings. A possible answer was to build a blast-mitigating wall between the buildings and possible blasts. The MM-ALE features of LS-DYNA provided a way to evaluate the effects of the wall on the pressure waves around the building. As the amount of explosive was rather small when compared to the distances involved, the new 2D to 3D and 3D to 3D re-mapping methods came in handy to avoid the use of an impractically large numerical model. After a first series of computation showed that the proposed solution was indeed promising, a series of simulation runs enabled the design of a wall tall enough to achieve the desired mitigation effect on the pressure waves experienced by the building’s walls and roof.

• Using LS-DYNA to Computationally Assess the V0-V100 Impact Response of Flexible Fabrics Through Probabilistic Methods

  Gaurav Nilakantan, Michael Keefe, John W. Gillespie Jr. - University of Delaware, Eric D. Wetzel, Travis A. Bogetti, Rob Adkinson - US Army Research Laboratory

  The probabilistic nature of the impact performance of flexible woven fabrics arises from a number of sources. The statistical nature of yarn tensile strengths on impact response is modeled in this study. Currently the probability of penetration of a fabric at a given velocity (Vx is the impact velocity having a probability of penetration of x ranging from 0 to 100%) is determined experimentally, by shooting fabric panels over a range of velocities and fitting the response data to a likely probabilistic function. This approach requires a large number of experimental test shots associated with significant cost, labor, and time in order to generate statistically meaningful results. In this study, we use the finite element (FE) analysis to study the impact response of flexible woven fabrics. A probabilistic framework is developed, that maps experimentally obtained yarn tensile strength distributions directly onto the FE model comprised of a yarn level architecture. Multiple impact simulations are run using a Monte Carlo approach. Through this novel probabilistic approach, the V0-V100 response of flexible woven fabrics can be predicted numerically. Further, a direct relationship between the statistical nature of yarn material properties and the probabilistic impact response of fabrics is established. This correlation allows an investigation into the effects of weaving and scouring degradations on the impact performance.

• Using LS-DYNA® from ANSYS Workbench Environment

  Dr.-Ing. Matthias Hörmann - CADFEM GmbH, Germany

  Numerical simulations as integral part in the virtual product development process exhibit a huge spectrum. Ranging from simple modal analyses over linear and nonlinear stiffness and strength based problems up to coupled multi- physic analyses, where different physical disciplines interact with each other. Thereby simulation tools in combination with preprocessors must enable users to perform product development tasks faster and therefore more efficient. One essential part is hereby the seamless model file transfer from and to 3D CAD systems. Additionally model and assembly handling in-between the different simulation disciplines in combination with an automatic mesh generation and automatic contact detection is also important to speed up development time. With the Workbench environment, ANSYS took a quantum leap into model analysis and handling different simulation disciplines in one standard user interface in combination with a tight interface from and to almost all common 3D CAD systems. An interface between ANSYS Workbench and LS-DYNA therefore provides the opportunity to use Workbench preprocessing functionalities for LS-DYNA simulations. The German ANSYS and LS-DYNA distributor CADFEM has thus created a unidirectional, interactive graphic interface “Workbench LS-DYNA“ for the transfer of data from ANSYS Workbench to LS-DYNA. This not only enables users to transfer the pure structure in form of nodes and elements, but also sections, materials, contact definitions and boundary conditions, including prescribed motions and force loading. LS-DYNA specific control and database options are included from a template file, which can be customized by the user. Moreover any LS-DYNA keyword command can be defined within the Workbench GUI and will be added into the LS-DYNA input file. Besides using CAD interfaces, automatic mesh generation and contact detection of Workbench, LS-DYNA users will benefit from this interface. With an existing ANSYS Workbench license and LSTC’s free of charge LS-PrePost an additional preprocessor causing cost and training effort may no longer be necessary. Even more important, the interface enables easier data exchange with other analysis departments using already ANSYS Workbench. Moreover the CAD interfaces in ANSYS Workbench also allow a closer link to construction departments.

• Using LS-DYNA® to Simulate the Thermoforming of Woven-Fabric Reinforced Composites

  Corey D. Morris, Lisa M. Dangora and James A. Sherwood (University of Massachusetts)

  Thermoforming of fabrics is a composite manufacturing process that has the potential to yield quality parts with production costs and cycle times comparable to the fabrication of stamped metal parts. The thermoforming process, illustrated in Figure 1, begins with alignment of the fabric in a rigid frame. Typically, multiple ply layers are simultaneously stamped into the mold to achieve the desired part thickness and mechanical properties. The individual plies can be oriented and aligned in the frame to give the desired directional performance. The loaded frame is transported along shuttle rails to an oven where it is heated until the polymer matrix is hot enough to flow with reasonably low viscosity. Because the traditional materials used for this manufacturing process are fabrics with commingled tows or pre-impregnated sheets, there is no need for a resin infusion step. The frame is moved from the oven to the molding area and aligned between a punch and die; binder plates are conventionally used to apply force around the circumference of the part. The application of pressure to the binder plate induces in-plane forces in the fabric that can reduce wrinkling as it is drawn into the die by the punch. A velocity is then prescribed to the punch to force the ply stack into the die mold. The tools (punch, die and binder plate) are often heated to slow the rate at which the polymer matrix cools. The finished piece assumes the geometry of the die and punch and hardens into a solid part after the matrix has cooled.

• Using LS-OPT for meta-model based global sensitivity analysis

  Uwe Reuter, Zeeshan Mehmood, Clemens Gebhardt - TU Dresden, Martin Liebscher, Heiner Müllerschön, Ingolf Lepenies - DYNAmore GmbH

  Popular sensitivity analysis methods such as ANOVA and SOBOL indices are widely used in LS-OPT in order to measure the importance of different input variables with respect to the model response. These methods are applied using meta-models in LS-OPT. In contrast, sensitivity information can be directly extracted from the meta-models using weight-based and derivative-based approaches. Meta-models capture the non-linear relationship of the underlying input parameters to the design response. In this paper, powerful sampling and pre-processing capabilities of LS-OPT are coupled with a user-defined neural network based meta-model in order to perform weight based and derivative based sensitivity analysis. The results of these sensitivity measures are compared with the default SOBOL approach by using an analytical as well as an industry relevant crash analysis example.

• USING LS-OPT/LS-DYNA IN A MULTI-ATTRIBUTE OPTIMIZATON

  Forsberg Jimmy, Björkman Gunnar - VTEC

  This paper summarizes the experiences of using the LSTC environment in a multiattribute optimization. The work was carried out in an on-going project, SuperLIGHTCar (SLC), which aims to reduce the weight of the body in white (BIW) of a compact class car by at least 30%. This objective is made possible by using new materials and a blend of materials in the design. The car should still fulfil user rating, e.g. Euro NCAP demands but also demands of production rate, cost, life cycle analysis, stiffness demands, etc.. The VTEC involvement in the SLC project is to perform structural optimization of the BIW with respect to the defined loadcases and corresponding target values for responses defined for each loadcase. In this paper the set up of the current optimization problem, resources needed and “work-arounds” are presented. The current optimization formulation requires the solution of 6 impact loadcases, 2 static loadcases and an eigenvalue problem. The final results from this investigation are still to be seen.

• Using LS_DYNA to find Failure modes during design process

  Dr. Tayeb Zeguer - Jaguar and Land Rover

  Understanding the customer needs Failure Mode List Generation Detection using CAE – Capability and Enablers CAE Execution Process and the use of DFSS principles Conclusions

• Using MAT213 for Simulation of High-Speed Impacts of Composite Structures

  Loukham Shyamsunder, Bilal Khaled, Canio Hoffarth and Subramaniam D. Rajan,, School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ;, Robert K. Goldberg, NASA-GRC, Cleveland, OH;, Kelly S. Carney and Paul DuBois, George Mason University, Fairfax, VA;, Gunther Blankenhorn, LSTC, Livermore, CA

  A general purpose orthotropic elasto-plastic computational constitutive material model has been developed to predict the response of composites subjected to high velocity impact. The three-dimensional orthotropic elasto-plastic composite material model is being implemented in a special version of LS-DYNA® for solid elements as MAT213. In order to accurately represent the response of a composite, experimental stress-strain curves are utilized as input, allowing for a more general material model that can be used on a variety of composite applications. The experimental procedures are discussed in a companion paper. This paper documents the implementation, verification and validation of the material model using the T800-F3900 fiber/resin composite material, a commonly used composite in the aerospace industry.

• Using MAT_ADD_INELASTICITY for Modelling of Polymeric Networks

  T. Borrvall, F. Bengzon, A. Jonsson (DYNAmore Nordic), M. Lindvall (IKEA)

  Thermoplastics are widely used in many industries today. Products such as packaging solutions, consumer goods, medical devices, furniture, electronic devices and vehicles are constantly demanding more and more sophisticated polymer components. In addition, sustainability agendas at many companies today means a necessity to transition from high spec petroleum-based polymers to recycled and biobased alternatives [1]. This creates a pressure on the CAE departments to assess candidate resins at a high pace and make fact-based judgements on their predicted life cycle performance. In a competitive market, there are good reasons to adopt best practice for predicting the life cycle performance of these polymers already during the design phase with the use of realistic simulation.

• Using Platform LSF To Harness Non-Dedicated Computational Resources for LS-DYNA Crash Simulations at DaimlerChrysler

  Dale Dunlap, Joseph Cieslak P.E. - Platform Computing, John Picklo - DaimlerChrysler Corporation

  Computer aided engineering (CAE) tools are an important part of the product development lifecycle. These tools are used to perform complex simulation and analyses during the design phase. CAE requires significant computational resources in order to meet the response time requirements of the design engineers that use these applications. The speed and volume of CAE work provides a competitive advantage to the manufacturer by helping to bring products to market faster, reducing the need to build costly prototypes, and by increasing the quality of the end product. This paper documents a comprehensive approach to extending the HPC cluster grid to DaimlerChrysler’s engineering workstations. This approach will allow DCX to transparently make use of idle workstation CPU cycles and thereby significantly increase overall computing power at a fraction of the cost of a comparable dedicated HPC solution. This solution will also provide the foundation for further grid deployment to the DCX infrastructure so that additional benefits can be achieved in the future. By collectively harnessing the latent power of existing resources, Platform and DCX feel it maximizes the value of assets already owned while it gains compute power to accelerate and refine research and analysis, without any impact on the daily usage of these workstation users. The typical utilization of a desktop in the enterprise is about 5-7%, and large enterprises have tens of thousands of desktops. This will provide a cost effective path for increasing computing power while avoiding additional procurements of HPC cpu’s during usage spikes.

• Using Tabulated Experimental Data to Drive an Orthotropic Elasto-Plastic Three-Dimensional Model for Impact Analysis

  C. Hoffarth, B. Khaled, S. D. Rajan (Arizona State University, Tempe), R. Goldberg, K. Carney (NASA-GRC, Cleveland), Gunther Blankenhorn (LSTC)

  An orthotropic elasto-plastic-damage three-dimensional model with tabulated input has been developed to analyze the impact response of composite materials. The theory has been implemented as MAT 213 into a tailored version of LS-DYNA ® being developed under a joint effort of the FAA and NASA and has the following features: (a) the theory addresses any composite architecture that can be experimentally characterized as an orthotropic material and includes rate and temperature sensitivities, (b) the formulation is applicable for solid as well as shell element implementations and utilizes input data in a tabulated form directly from processed experimental data, (c) deformation and damage mechanics are both accounted for within the material model, (d) failure criteria are established that are functions of strain and amage parameters, and mesh size dependence is included, and (e) the theory can beefficiently implemented into a commercial code for both sequential and parallel executions. The salient features of the theory as implemented in LS-DYNA are illustrated using a widely used composite – the T800S/3900-2B[P2352W-19] BMS8-276 Rev-H-Unitape fiber/resin unidirectional composite. First, the experimental tests to characterize the deformation, damage and failure parameters in the material behavior are discussed. Second, the MAT213 input model and implementation details are presented with particular attention given to procedures that have been incorporated to ensure that the yield surfaces in the rate and temperature dependent plasticity model are convex. Finally, the paper concludes with a validation test designed to test the stability, accuracy and efficiency of the implemented model.

• Using the CESE Immersed Boundary FSI Solver to Simulate the FSI of the Front Portion of a Turbofan, including Damage

  Grant Cook, Jr, Zeng-Chan Zhang, Gunther Blankenhorn (Livermore Software Technology, an ANSYS Company)

  In this paper, we demonstrate use of the LS-DYNA®. Conservation Element/Solution Element (CESE)[1] solver doing fluid-structure interaction (FSI) calculations employing its immersed boundary FSI method[2,3]. The fan rig used is a portion of the fan blade-off rig test for a generic fan rig model. The model is available through the LS-DYNA. Aerospace Working Group (AWG) at http://awg.lstc.com. In this model, programmed failure of some of the structural elements is set up in one blade near the fan hub. Two cycles of operation are analyzed with and without FSI, and then the failure situations will be demonstrated with and without FSI active.

• Using the Latest Cloud Technology to Accelerate LS-DYNA®

  Rodney Mach (TotalCAE)

  This paper will focus on the latest technologies available on cloud to accelerate LS-DYNA using the major IaaS vendors including Amazon AWS and Microsoft Azure, and how they impact the total simulation job cost of a LS-DYNA benchmark model.

• Using the New Compressible Fluid Solver in LS-DYNA CESE Solver and the Input File Setup

  Zeng-Chan Zhang - Livermore Software Technology Corporation

  In this new compressible fluid solver, the conservation element and solution element (CESE) method[1, 2] is used. The CESE method is a novel numerical method for solving conservation laws and it has many nontraditional features, such as: • Space and time conservation ⎯ Flux conservation can be maintained very well both locally and globally in space & time. • Accurate ⎯ It is 2nd order for both flow variables and their spatial derivatives. Thus, it is more accurate than other 2nd order schemes. • Novel & simple shock-capturing strategy ⎯ only a simple weighted averaging technique is used, no Riemann solver and no special limiters are needed to capture shocks. • Both strong shocks and small disturbances can be handled very well simultaneously. Because of these advantages, this CESE solver is a good choice for the following problem simulations: • Compressible flow problems, especially for high speed flows with complex shocks. • Acoustic (noise) problems (near field). This solver is also combined with the LS-DYNA® structure solver to solve the fluid structure interaction (FSI) problems. There, the fluid solver is based on the Eulerian frame while the structure solver is the Lagrangian one. These meshes are independent of each other, and the interfaces will be tracked by the fluid solver automatically. A quasi-constraint method is used in the interface treatment, i.e., the fluid solver get the displacements and velocity of the interfaces from the structure solver and feeds back the fluid pressures (forces) on the interfaces. Currently, both serial & MPP models are available for this compressible fluid & FSI solver (in LS-DYNA® 980 β- version). The fluid mesh can be made up of hexahedra, wedges, tetrahedra, or a mixture of these elements, while the structural mesh can be made up of shells (thin) or solid volume elements. In this talk, a brief review of this new compressible fluid solver will be given first. Then, an introduction of how to use this new solver will be emphasized, including: • Computational domain & mesh determinations, especially for FSI problems • Input deck (keywords cards) setup ⎯ some general control parameters for the method ⎯ initial flow field setup ⎯ boundary condition (BC) choice at each boundary • The use of LS-PrePost® for this new solver’s output In addition, some new features will be introduced, followed by some remarks. The limitations of this solver will be pointed out too. Finally, some features under development will be mentioned.

• UsingLS-OPT for Parameter Identification and MAT_FABRIC with FORM=-14

  David Dubois (Autoliv), Jimmy Forsberg (DYNAmore Nordic AB)

  This work was carried out as a methodology development project in a joint venture between Autoliv and DYNAmore Nordic AB. The outset of the project was to obtain a better component behavior due to a more realistic material behavior in the simulation of airbag models. The observation underlying the project was that the current fabric model used in most airbag models is *MAT_FABRIC and FORM=14. In FORM=14 there is no consideration taken to a stiffened response due to a bi-axial stress state in the fabric. To consider the bi-axial stress state, FORM=-14 was implemented some years ago but has, until now, not been used. The objective with this implementation is to increase the stiffness in the fabric when subjected to a bi-axial stress state. This paper presents a resume of the features found in *MAT_FABRIC, a methodology to fit the simulation model to material test data using LS-OPT and finally a comparison between the behavior of the different FORM options.

• Utilizing a Validated Laminated Glass Model to Simulate Pedestrian Head Impact on a Windshield

  Marc Tatarsky, Ben Crone, Daniel Aggromito

  The authors have previously published a paper characterizing a laminated glass pane to simulate the delamination and fragmentation response of glass in a blast event. In this study, a computational model in LS-DYNA was developed and correlated with physical testing of laminated safety glass panes subjected to blast loads. To generate an accurate model, validation of the component parts including Polyvinyl Butyral (PVB), adhesion and glass that make up the laminated safety glass was completed.

• VALIDATED CRASH SIMULATION OF THE MOST COMMON GUARDRAIL SYSTEM IN THE USA

  Jin Wu - University of Cincinnati

  Ala Tabiei Director CENTER OF EXCELLENCE IN DYNA3D ANALYSIS Department of Aerospace Eng. & Eng. Mechanics University of Cincinnati The subject of this investigation is the development of an accurate simulation of a truck impacting a strong-post w-beam guardrail system, the most common system in the USA. Detailed methods for system simulation are proposed and three major issues, which involve the use of springs to simulate component crashworthiness behavior, are investigated. Rail to blockout bolt connection, soil-post-dynamic interaction, and effect of ends of guardrail are modeled and simulated. Soil-post interaction is modeled using both Lagrangian and Eulerian meshes and the results using the two methods are presented. Both qualitative and quantitative validation of the crash simulation is presented and discussed. The present paper provides a roadmap for simulation of highway safety structures.

• VALIDATING DYNAMIC TENSILE MECHANICAL PROPERTIES OF SHEET STEELS FOR AUTOMOTIVE CRASH APPLICATIONS

  P.K.C. Wood, C.A. Schley - University of Warwick, M. Buckley - Jaguar and Land Rover, B. Walker - ARUP, T. Dutton - Dutton Simulation

  A thin-wall open channel beam, fabricated from high strength Dual Phase sheet steel, subjected to 3-point bending and constant velocity boundary condition, is investigated to validate material performance for automotive crash applications. Specifically quantitative validation of material tensile data determined from high speed tests and component models, and qualitative validation of materials resistance to fracture. The open channel beam is subjected to quasi-static and increasing loading speed and in all cases, large displacement in which deformation involves formation of a plastic hinge. This paper describes development of test procedure, notably beam specimen design, measurement system and boundary conditions, using both experimental and numerical techniques. The new test procedure, as a compliment to crush testing, will increase confidence in the modeling and application of new advanced higher strength materials in automotive crash structures.

• Validating Innovative Design Solutions - Analysis of the Gerald Desmond Bridge Replacement

  Francois Lancelot, Dong-Ling Li, Mark Nelson, Matt Carter (Arup)

  In 2011, the Port of Long-Beach, in collaboration with Caltrans and LA Metro, awarded the Design and Build contract for the replacement of the deteriorating Gerald Desmond Bridge to SFI Construction (Schimmick / FCC /Impregilo joint-venture). Arup had been lead designer for SFI’s tender proposal, providing structural andgeotechnical engineering, traffic operations analysis, lighting design and civil engineering services. Arup designed an elegant mono-pole stayed-cable solution that met all the project requirements while providing dramatic cost- savings to the Client. The team’s innovative solution earned the judges’ highest ratings for both technical design and price and ultimately won the job. The deployment of advanced LS-DYNA ® analysis capabilities was instrumental in assessing the structural options against the stringent project requirements. The extreme seismic demands of the 1000-year Safety Evaluation Event (SEE) could be addressed by isolating, by means of viscous dampers, the Main Bridge deck from the Towers and by introducing a ground-breaking approach for the design of the ductile hollow-section columns. These innovative solutions, among other particular features of the bridge, required detailed Finite Element modelling and validation through explicit nonlinear time-history analysis. This paper presents some of the key modelling techniques and analyses results that contributed to the successful development of this new landmark.

• Validating Material Information for Stochastic Crash Simulation Part 1: Quasi-Static Properties

  P.K.C Wood, C. A. Schley, S. Kenny - University of Warwick, T. Dutton - Dutton Simulation

  This paper describes the steps in validating material information for stochastic simulation using a quaisi-static tensile test experiment. Sources of physical noise usually present in a testing environment such as variation in material properties, geometry and boundary conditions are included as inputs to Finite Element models. This work is carried out in the context of a research project supported by the Automotive Industry in the Midlands. The broad aim of the project is to establish a material properties validation process for crash simulation. Stochastic models of representative components and small assemblies in a vehicle structure, in addition to tensile testing of coupons, will be created and will form an essential part of the verification process. All models will be validated through experimental testing and these investigations will establish variations in material properties and the significance of dependencies such as strain rate and form induced thinning. Stochastic simulation is a CAE tool, enabling the support of robust engineering design. Robust engineering design is viewed as an essential part of automotive product development.

• Validating Performance of Automotive Materials at High Strain Rate for Improved Crash Design

  K.C. Wood, C. A. Schley, S. Kenny - University of Warwick, IARC, T. Dutton - Dutton Simulation, M. Bloomfield - Land Rover, R. Bardenheier - Inston Ltd, J. R. D. Smith - ARRK Technical Services

  This paper investigates sources of performance variability in high velocity testing of automotive crash structures. Sources of variability, or so called noise factors, present in a testing environment, arise from uncertainty in structural properties, joints, boundary conditions and measurement system. A box structure, which is representative of a crash component, is designed and fabricated from a high strength Dual Phase sheet steel. Crush tests are conducted at low and high speed. Such tests intend to validate a component model and material strain rate sensitivity data determined from high speed tensile testing. To support experimental investigations, stochastic modeling is used to investigate the effect of noise factors on crash structure performance variability, and to identify suitable performance measures to validate a component model and material strain rate sensitivity data. The results of the project will enable the measurement of more reliable strain rate sensitivity data for improved crashworthiness predictions of automotive structures.

• Validating wear simulations in heat exchanger plate stamping process through comparative analysis for enhanced productivity and quality

  Donghui Fang, Kang Shen, Xiaolong He

  Tool wear is a common problem in the manufacturing process of heat exchanger plates. The shape of HP changes due to tool wear, causing issues in subsequent processes such as welding, brazing, and assembling. In this paper, a simulation model of heat exchanger plates using Ansys Forming® is created to predict tool wear. It provides guidance for the shape design of heat exchanger plates, aiding in the planning of tool repair and replacement.

• Validation and Material Modeling of Polymers by Employing MAT_SAMP-1

  K. Takekoshi, K. Niwa (Terrabyte Co.)

  We have developed a method to determine plastic Poisson’s ratio and its corresponding stress – strain curves, where newly redefined true stress expression including elastic and plastic Poisson’s ratios is employed. The plastic Poisson’s ratio is used to predict permanent volumetric deformation which is one of the mechanical characters associated with crazing. Although the crazing is one of the most important issues to be tackled in analysis, methods to determine the plastic Poisson’s ratio and its corresponding data have not been discussed sufficiently in previous papers. Thus we show and discuss how we determine and validate these data. Additionally, in order to complement the method, we provide two techniques to utilize MLYS (Multi-Linear Yield Surface) and to evaluate damage property. We show MLYS could make analysis incorporating isochoric plasticity in compressive state stable. Furthermore we show that these methods are valid and useful through the numerical results.

• Validation and Material Modelling of Plastics

  A. Haufe , V. Effinger - DYNAmore GmbH, P. Reithofer , M. Rollant , M. Fritz - 4a engineering GmbH

  The virtual estimation of physical product properties is only as good as the virtual description of the behaviour of its material. On the one hand there are well known material cards like *MAT_PIECEWISE_LINEAR_PLASTICITY in LS-DYNA© developed to describe a simplified behaviour of metallic materials. The reduced complexity of these material cards makes it possible to determine its parameters with less effort in actual material testing. Main advantages are high numerical stability and less machine time. On the other hand complex material models like *MAT-SAMP-1 can also handle varying compression and tension behaviours by defining a load case dependent yield surface as well as unloading by using damage functions. With the exception of visco-elasticity the description of visco-plasticity fulfills many requirements to describe a realistic behaviour of thermoplastics. For acceptable use of the above mentioned models a higher amount of load cases like tension, compression, shear have to be carried out to determine the material parameters and to represent the thermoplastic characteristics in crashworthiness simulations. At the moment there is no standardized method to determine material card properties for arbitrary material models from basic (i.e. tension, compression or shear) test setups. 4a impetus represents a standardized method, an efficient and reliable process starting with realistic test scenarios and finally ending up with a validated material card. The method of reverse engineering is used behind this process to generate material cards like *MAT_PIECEWISE_LINEAR_PLASTICITY as well as more complex *MAT_PLASTICITY_COMPRESSION_TENSION with regard to easy and favourable testing. We have compared different ways to determine and validate material cards with the example of PA6. Limits and opportunities of different test methods and material card implementations are shown and compared to each other especially focused on typical polymer behaviour.

• Validation of a Loading Model for Simulating Blast Mine Effects on Armoured Vehicles

  Kevin Williams, Robert Durocher, Benoit St-Jean, Jocelyn Tremblay - Defence R&D Canada - Valcartier, Scott McClennan - University of British Columbia

  An ongoing program at Defence R&D Canada to reduce the vulnerability of Light Armoured Vehicle (LAVs) to anti-vehicular blast mines is relying heavily on LS-DYNA to help design and optimize add-on armour systems. A significant challenge in the numerical modelling work is the development of an accurate, or at least representative, loading history for the pressure and momentum transfer from the detonation of a buried blast mine. Arbitrary Lagrange-Eulerian (ALE) techniques offer some promise but the analysis is very computationally intensive. Another option that is more attractive from the point of view of simplicity (implementation and computation time) is an empirically based loading model. The LS-DYNA implementation of the CONWEP blast equations (*LOAD_BLAST) is one such example. While some authors have used this model to predict the effects of mine blasts on vehicle structures, there are significant limitations in this model. A more advanced empirical model for predicting the effects of blast mines on structures was developed for the U.S. Army Tank Automotive Command (TACOM) by Southwest Research Institute. This model has been implemented by the Defence R&D Canada - Valcartier (DRDC - Valcartier) in a pre-processor for LS-DYNA. A parameter study has been conducted using this implementation of the impulse model and the results are compared to those obtained from the CONWEP blast model. Validation is based on a series of experiments conducted at DRDC - Valcartier using square aluminium and steel test panels subjected to detonations of buried charges (surrogate mines) of 6 kg of C-4 explosive.

• Validation of a Newly Developed Cross-Flow High Temperature Heat Exchanger (HT-HE) using Multiphysics Simulation

  M. Rübsam, Prof. R. Altensen, Prof. M. Pitzer (THM)

  Heat-exchangers are devices used to transfer heat between two or more fluids and can be found in both heating and cooling processes. At high temperatures during operation, thermal induced stresses occur and can lead to the failure of the device. The Technische Hochschule Mittelhessen has, in cooperation with the company WK, started a research project for the development of a HT-HE, which is designed for operating temperatures up to 1100°C and the contact with aggressive chemical media. In order to develop an efficient HT-HE regarding the heat recovery, semi analytical calculations have been carried out to optimize the geometry of the heat exchanger. This study focusses on the validation of these semi-analytical calculations by using Multiphysics simulation. Due to the time costly simulation of transient fluid-structure-interactions (FSI) while taking high temperatures into account, special emphasis has been placed on the reduction of simulation time without losing accuracy. Initially, a number of simplified models were set up to control the bug-free operation of the relatively new ICFD-Solver. It has been shown that the necessary workarounds, due to some implementation errors, only had a minor effect on the heat transfer. Modifications have been added to the input data in order to significantly reduce simulation time without affecting the quality of results. The results of the simulations done with LS-DYNA show a qualitatively good correlation with the semi analytical calculations and improve the understanding of the thermo- and fluid dynamic processes inside the HT-HE during operation.

• Validation of a Thermal Radiation Problem using *BOUNDARY_RADIATION_ENCLOSURE

  G. Blankenhorn, R. Grimes, F.-H. Rouet, I. Gandikota (LSTC), B. Gysei, S. Malcom (Honda R&D)

  Thermal radiation problems are gaining interest in the automotive industry. Examples include paint drying and curing processes, determining material characteristics and deformation due to heat treatment, temperature distributions in muffler systems and heat shields in engine compartments. LS-DYNA has capabilities to couple the thermal solver with mechanical and multi physics solver. Solving for thermal convection, conduction and contact in three dimensions are already available in all parallel models LSTC are offering, namely shared memory parallel (SMP), massive parallel processor (MPP) and the combination of both models (HYBRID). Lately the thermal radiation feature has been extended to be used with massive parallel processor (MPP) version and a new solver to solve for radiosity. New developments are tested with verification examples and small test cases to determine the code functionality and expected results. Furthermore they have to show their applicability with validations of numerical models with experimental data. They also need to be evaluated regarding their scalability of wall clock time to reduce costs of compute resources. This contribution addresses two of these subjects, the scalability and the validation. The validation example used here is a part of a B-pillar which is heated up in an oven. Temperatures were measured at several locations of the sheet metal. Test data was provided by Honda R&D Americas, Inc. The test was modeled as a thermal radiation problem in an enclosure. Thermal radiation was modeled using the keyword *BOUNDARY_RADIATION_ENCLOSURE and was performed in LS-DYNA MPP. An LS-DYNA MPP scalability study was performed. Due to missing data for the thermal parameters, the heat capacity, thermal conductivity and emissivity were determined with LS-OPT.

• Validation of Finite Element Crash Test Dummy Models for the Prediction of Orion Crew Member Injuries during a Simulated Vehicle Landing

  Ala (Al) Tabiei - Mason, Ohio, Charles Lawrence - NASA Glenn Research Center, Cleveland, OH, Edwin L. Fasanella - NASA Langley Research Center, Hampton, VA

  A series of dummy response during a simulated Crew Exploration Vehicle (CEV) module landing is conducted at the Wright-Patterson Air Force Base (WPAFB). These tests consisted of several crew configurations with, and without astronaut suits. Finite element models of the tests are developed and presented herein. The finite element models are validated using the experimental data. Several outputs from the dummy are collected and presented here in. These outputs are compared with the outputs of the finite element model. Occupant crash data such as forces, moments and accelerations are collected from simulations and compared to the presented injury criteria to assess Occupant Survivability and Human Injury. Some of the injury criteria published in the literature are summarized herein for sake of completeness. These injury criteria are used to determine potential injury during such impact event.

• Validation of Fluid Analysis Capabilities in LS-DYNA Based on Experimental Result

  S. Tokura (Tokura Simulation Research)

  The latest LS-DYNA provides several excellent capabilities for modeling of fluid like materials. These capabilities contains ALE, SPH and CESE for compressible fluid and ICFD for incompressible fluid. Each capability has its own numerical method for computation and characteristics, and is used properly for different target of modeling and purpose of each simulation. For example, ALE and SPH can treat free surface problem automatically without any additional definition of free surface boundary, whereas, explicit definition of free surface boundary is required in ICFD computation.

• Validation of Hydraulic Gas Damper Coupler and Crash Simulation of Large Rolling Stock Model in LS-DYNA®

  F Lancelot (ARUP), YH Zhu2, BH Li, KF Wang, CL Li (Changchun Railway Vehicle Co., Ltd)

  The hydraulic gas damper coupler (HGDC) is the most important energy absorbing component in rolling stock crash impact. The HGDC can effectively dissipate crash energy and reduce excessive structural loads at all impact speeds. In this paper, the LS-DYNA material *MAT_HYDRAULIC_GAS_DAMPER_DISCRETE_BEAM (*MAT_070) is used to simulate the HGDC coupler. Using this formulation, both static and dynamic characteristics have been replicated. The validated HGDC models have been incorporated into rolling stock frontal impact simulations. A simple mass-beam representation for the carriages and a full scale detailed model – containing 16 carriages and more than 28 million elements – have successively been analysed. This paper also presents the innovative pre-postprocessing and data storage methods developed by CNR and Arup to handle the very large FE models and results files.

• Validation of LS-DYNA Computer Code for Seismic Qualification of Reactivity Control Mechanisms

  A.S. Banwatt, C. Manu, C. Yao - Atomic Energy of Canada Ltd.

  Reactivity control mechanisms of CANDU reactors fall under two categories: The first are mechanisms to control the reactivity and power output of the reactor and the second are mechanisms to control the reactor and provide instrumentation for indication. In this paper the shut off mechanism, which is of the second category, is analyzed to seismically qualify it using LSDYNA, a general-purpose finite element computer code based on the explicit time integration method. One of the objectives of this work is to determine the drop time of the shut off mechanism that ensures the safe shut down of the reactor when required. This mechanism consists of a slender structure that extends over a relatively long travel. During the mechanism’s drop, the shut off rods are guided by stationary components, which results in surface-to-surface contact and friction. Drag and damping forces are also acting on the moving parts. Due to a built-in eccentricity in the mechanism, it generates forces in the horizontal directions while the reactivity mechanism is dropping. Maximum stresses during the drop of the mechanism are evaluated to demonstrate that the jurisdictional requirements for the various components are met. The results obtained from the finite element analysis are compared with those from static drop tests performed in the laboratory. The drop test results are used to modify the finite element model by fine-tuning various variables such as the drag force, spring constants, damping and friction coefficients between the components, etc. Once the model has been verified, the seismic motion is applied and the results are compared with test data from similar reactors. It is shown that the results of the analysis of the reactivity mechanism compare well with the test data and the deformation and stresses are well within the acceptable values. These results demonstrate that the LSDYNA code can be successfully applied to seismically qualify a CANDU reactivity control mechanisms.

• Validation of LS-DYNA MMALE with Blast Experiments

  Y. Huang, M. R. Willford (Arup), L. E. Schwer (Schwer Engineering & Consulting Services)

  The general multi-material arbitrary Lagrangian-Eulerian (MMALE) solver is available in the finite element ®analysis software LS-DYNA . In the context of blast simulation, this solution approach involves explicit modeling of the explosive, the blast transmission media and the structure subjected to the blast within the MMALE solver. This paper presents a validation study of the LS-DYNA MMALE approach with existing experimental studies of blast wave clearing and blast in an urban environment, as well as numerical results from the finite volume method software Air3d. The overpressure histories, peak overpressures and impulses are compared. It is demonstrated that the results from LS-DYNA produce excellent correlation with experimental and Air3d simulation results. Whilst this is a validation with prior knowledge of the experimental results, it suggests that the LS-DYNA simulation capability is accurate for the cases studied.

• Validation of Material Models for the Numerical Simulation of Aluminum Foams

  Marco Perillo, Vito Primavera - EnginSoft SpA, A. Carofalo, M. De Giorgi, R. Nobile - University of Salento

  In the last years a lot of studies dealt with the material modeling of metallic foams, especially for the Aluminum ones. All these activities were performed especially for automotive field applications because the high energy- absorbing property of such foams fits very well the requirement to carry impacting loads efficiently. In spite of this, the industrial applications are not yet so widespread both for manufacturing costs and for a lack of knowledge regarding a whole mechanical characterization. The anisotropic properties of the foams induced mainly by the manufacturing processes, like the continuous casting procedure [1,2] is the reason due until now it has not been possible to assess in a well-known way the foams mechanical performances. In function of the wide spectrum of loading configurations, foaming direction, open and closed cells typology, cells morphology, density, thickness, etc., the output data regarding the mechanical tests are largely scattered (e.g. the stress/strain curves change according to the direction along the experimental test is performed), so a numerical model designed to reproduce accurately the foam behavior needs to take into account the parameters affecting the foam response...

• Validation of Mine Blast Simulations with Field Tests

  İlker Kurtoğlu, Berkay Salihoğlu, Y. Caner Taşan, Gökhan Tekin (FNSS Savunma Sistemleri A.S.)

  In this work, LS-DYNA® simulation results of mine blast of flat aluminum/steel plates and validation studies using mine blast tests are presented. The buried mine simulations are performed using ALE initial volume fraction and SPH methods. The high strain rate Johnson Cook material models of the plates are obtained through Split Hopkinson Pressure Bar tests, for both high strength steel and aluminum specimen. The soil parameters such as density and humidity ratio are determined by appropriate tests. Structural acceleration and strain data as well as blast pressures are measured during the field mine blast tests. A test setup is designed and manufactured in order to conduct the tests. This setup consists of dead weights for constraining the plate during the explosion. For measuring the plastic and total deformation of the plates, a novel method using thin walled aluminum cones are used. High speed and high bandwidth data acquisition systems are used to capture the highly dynamic behavior of the plates. Moreover, incident and reflected blast pressures from various distances are measured and compared with analytical methods, LS-DYNA simulations and bikini gage measurements. In this way, explosive and blast characteristics are verified. The correlation and similarity of simulation and test results for acceleration and deformation characteristics are presented. The results obtained by LS-DYNA simulations show very good agreement with results obtained in the field tests.

• Validation of the ALE Methodology by Comparison with the Experimental Data Obtained from a Sloshing Tank

  Alexander L. Kozak, Payman Khalili Tehrani, T. Eric Abrahamson, Alexander V. Krimotat (SC Solutions, Inc., Sunnyvale)

  Arbitrary Lagrangian – Eulerian (ALE) methodology has been used in Fluid - Structure Interaction (FSI) analyses with LS-DYNA ® for a variety of problems. Validation of ALE solutions by comparison with experimental data provides assurance that the solutions represent the physical world. A water tank under horizontal harmonic excitation tested by O. M. Faltinsen and O. F. Rognebakke [1] is used for validation. The experimental time histories of water surface motion are compared to those obtained from the ALE solution. Both free surface sloshing and the wave impact with the roof are analyzed and compared. The LS-DYNA analytical results match the experimental data very well. Different ALE formulations and mesh densities are explored and their respective solution times are compared. In addition, the ALE and experimental maximum wave heights are compared with the prediction by closed form solutions.

• Validation of the CHEMISTRY Solver in LS-DYNA

  R. Nasouri (University of Texas), H. Rokhy (Amir Kabir University), A. Montaya, A. Matamoros (University of Texas), R. Backzadeh (Urmia University)

  The CHEMISTRY solver has been added to the LS-DYNA software, enabling users to model and predict accidental gas explosions in refinery plants, pipelines, and coal mines. Although this new solver has shown theoretical potential in chemical, oil and gas refineries, there are limited studies implementing the capabilities provided by the CHEMISTRY solver. In this study, a series of fundamental chemistry problems were simulated, to compare the numerical results with existing experimental data. This study finds excellent agreement between solver results and experimental data, proving a high level of precision obtained through the CHEMISTRY solver.

• Validation of the Simulation Methodology for a Mobile Explosive Containment Vessel

  David Karlsson (DYNAmore Nordic AB)

  A Mobile Explosive Containment Vessel (MECV) is a chamber for protection against effects caused by explosions and is used to safely secure, contain, transport, store or test explosive materials. The MECV has been tested for a charge equivalent to 8 kg of TNT and strain levels at several positions were measured. These test data were used for comparison and validation of two simulation techniques and if necessary improve the simulation methodology. The first technique uses a separate 2D-axisymmetric MMALE simulation for the explosive blast load calculation and it showed good agreement to the test. In this case, an axisymmetric blast simulation is first made and the pressure is recorded at the fixed boundary. Then an in-house developed program is used to map the blast load to the 3D structure simulation. The second, much more compute intensive technique, is to do a full 3D coupled MMALE simulation of the blast and structure. The second technique lead initially to lower strain levels compared to the test and a more detailed parameter study had to be performed to improve the simulation results. As conclusion, we now have two validated simulation techniques and procedures to make realistic explosive simulations of containment vessels.

• Validation of Thums Human Model Throw Distance in Pedestrian Accident Scenarios

  M. Orlowski, C. Bastien, M. Bhagwani (Coventry University)

  Increasing number of hit and run pedestrian accidents highlight the importance of accident reconstruction tools used in forensic investigations. The tools used nowadays are based on simplified assumption of particle – particle interactions (Searle’s model), or real life accidents (Happer’s model) which enable for prediction of the collision velocity based on pedestrian throw distance evidence obtained at the scene of the accident. Unfortunately, vehicle impact speeds can only be estimated as a range of velocities, as the Searle’s model forms a velocity corridor which widens with the increase of measured throw distance giving not accurate predictions. Development of computing architecture together with the advancement in computer human modelling opens the opportunity for bringing accident reconstruction studies to the next level and reducing the predicted velocities range. Nevertheless, to achieve this, the computer human models need to be reliable and robust. In this study, the Total Human Model for Safety (THUMS) was validated against analytical pedestrian throw distance models. The validation studies were performed with THUMS 4.0 at three different model stances and four different impact velocities (20, 30, 40 and 50 km/h) as well as three different stances, namely: standing, walking and running pedestrian. Analyses results were validated against Searle’s and Happer’s throw distance models. THUMS kinematics agreed well with the current accident reconstruction tools in terms of model behavior and predicted throw distance. The behavior of the THUMS model is different for low and high velocity impacts showing good agreement to the field data in terms of body kinematics. In particular, low impact velocities cause forward projection of the human body, while high impact velocities are characterised by the wrap trajectory of the THUMS model.

• Validation ofModel fora Thermoplastic Composite Material Low Carbon Vehicle Applications

  Oliver Tomlin (GRM Consulting Ltd), Neil Reynolds (WMG, University of Warwick)

  The methods developed for creating and validating a thermoplastic composite (TPC) material model in LS-DYNA are presented. Included are details of the mechanical characterisation methods and test types required to fulfil the input requirements of MAT058. Model input data are validated through correlation between coupon and sub-system physical tests and simulations with justification of the boundary conditions. The test methods are explored in more detail following the sub-system model validation, giving a clear understanding of the need for integration between CAE and test. Validation of the material model is further explored with results from quasi-static and impact tests. Results show that confidence in the predictive capabilities of MAT058 is high.

• Validation Process of the Electromagnetism (EM) Solver in LS-DYNA v980: The TEAM Problems

  I. Caldichoury, P. L'Eplattenier (Livermore Software Technology Corp.)

  LS-DYNA version 980 includes an electromagnetic (EM) solver that can be coupled to the solid mechanics and thermal solvers of LS-DYNA to take full advantage of its capabilities to successfully solve complex industrial applications such as magnetic metal forming or welding, induced heating, and so forth. This paper will provide some insight on the validation process that is currently under way and focus on the so-called TEAM (Testing Electromagnetic Analysis Methods) problems. TEAM Workshops are meetings of an open international working group aiming to compare electromagnetic analysis computer codes. A series of TEAM Workshops was started in 1986 and has been organized in two-year rounds, each comprising a series of "Regional" workshops and a "Final" Workshop, as a satellite event of the COMPAQ Conference. The TEAM problems consist in a set of test-problems, with precisely defined dimensions, constitutive laws of materials, excitations, etc., each backed by a real laboratory device, on which measurements can be made. The range of the TEAM problems cover a wide area of applications and features such as moving or non-moving conductor parts, magnetic elements, conductors in time dependent magnetic fields and so forth. Several TEAM test cases and their simulation results that are part of the global validation process of the solver will therefore be presented highlighting some features and application domains of the solver.

• Validation Simulation of New Railway Rolling Stock Using the Finite Element Method

  Martin Wilson, Ben Ricketts

  Bombardier Transportation is the largest manufacturer of rail vehicles in the world. The current product portfolio includes a wide variety of vehicles from low speed ‘people movers’ through to high speed inter-city trains. Bombardier offers products in every sector of the passenger rail equipment market and therefore is required to meet a number of national and international crash safety requirements. These requirements range from simple static collapse loadcases to full collision events with other rail vehicles and obstacles. As part of the validation procedure for new designs, finite element (FE) models are produced to simulate new vehicle crash performance against targets set by these requirements. The simulation of bolted and welded aluminium structures is particularly important for the Carbodies part of the business, since recent ‘real life’ crash cases have shown bolt failure and weld ‘unzipping’ as critical collapse modes for extruded aluminium carbody designs. The current technique used for modeling welded aluminium sections and particularly the heat affected zone (HAZ) is presented. Bolt failure modeling within large structures is also addressed and results are presented from calibration tests and simulations carried out to evaluate the failure behaviour of Huck Bolted connections. This paper presents an overview of the current state of the art in the rail industry and describes, through various case studies, the approach that Bombardier Transportation uses for validation of new vehicles. These case studies also show novel aspects of new vehicle design, which increase safety and highlight the commitment of Bombardier Transportation to a ‘design for crashworthiness’ approach to new passenger vehicles.

• Validation Studies for Concrete Constitutive Models with Blast Test Data

  Youcai Wu, John E. Crawford, Shengrui Lan, Joseph M. Magallanes (Karagozian & Case)

  Many concrete constitutive models are available for use in LS-DYNA®. A thorough validation related to their applicability for the types of problems at hand should be made before application of any of these models. The process for validating a constitutive model includes examining the results produced with the model related to the behaviors it exhibits, gathering a suite of measured data collection pertinent to the problem to be addressed, and comparisons of measured and computed data. This paper addresses issues related to blast response analyses, which include simplification of boundary conditions (such as support condition and contact interfaces), numerical discretization, and material modeling. It was found important that the strain rate effects should be imposed properly since blast loadings usually excite high frequency and high strain rate responses. The impact of boundary conditions was also identified through the numerical studies.

• Variable Complexity Modeling for Speeding Up Multi- Run-Design-Tasks with Computationally Expensive Simulations

  Dr.-Ing. Holger Wenzel - SIMULIA SLM Europe

  Optimization and the improvement of robustness and reliability in the early stages of the product development is often attempted today using simulation methods together with algorithms that run these simulations in an automated manner. In this context the need often arises, to run the simulation models with small changes of the geometry hundreds to tenth of thousands times. If these simulations are computationally expensive, like a full vehicle crash analysis, the wall clock time to perform the runs is often prohibitively large. Even the usage of big compute clusters cannot always remedy this problem. For this reason approximation methods are often used. But no matter what actual technique is employed, polynomial approximations, radial basis functions, kriging or support vector machines, these techniques are purely mathematical and don’t have any knowledge about the physical problem they approximate. This paper presents a different approach. Here the same physical phenomenon is modeled using two different simulation models. One is very accurate but computationally expensive, the other is less accurate but computes faster. Both models are used to simulate the baseline design and the difference is recorded either as an additive correction delta or multiplicative correction factor. Then the multiple runs of the optimization algorithm or stochastic technique are performed using only the low fidelity quick code, and the correction is applied. When the baseline point is sufficiently far away from the actual point the correction delta or factor needs to be updated. This methodology is explained on a Taguchi Robust Design study for a full vehicle side crash using LS-Dyna. The focus of this paper is to explain the methodology, not to discuss the results.

• Variable Complexity Modeling for Speeding Up Multi- Run-Design-Tasks with Computationally Expensive Simulations

  Dr.-Ing. Holger Wenzel - SIMULIA SLM Europe

  Optimization and the improvement of robustness and reliability in the early stages of the product development is often attempted today using simulation methods together with algorithms that run these simulations in an automated manner. In this context the need often arises, to run the simulation models with small changes of the geometry hundreds to tenth of thousands times. If these simulations are computationally expensive, like a full vehicle crash analysis, the wall clock time to perform the runs is often prohibitively large. Even the usage of big compute clusters cannot always remedy this problem. For this reason approximation methods are often used. But no matter what actual technique is employed, polynomial approximations, radial basis functions, kriging or support vector machines, these techniques are purely mathematical and don’t have any knowledge about the physical problem they approximate. This paper presents a different approach. Here the same physical phenomenon is modeled using two different simulation models. One is very accurate but computationally expensive, the other is less accurate but computes faster. Both models are used to simulate the baseline design and the difference is recorded either as an additive correction delta or multiplicative correction factor. Then the multiple runs of the optimization algorithm or stochastic technique are performed using only the low fidelity quick code, and the correction is applied. When the baseline point is sufficiently far away from the actual point the correction delta or factor needs to be updated. This methodology is explained on a Taguchi Robust Design study for a full vehicle side crash using LS-Dyna. The focus of this paper is to explain the methodology, not to discuss the results.

• Variable Screening Using Global Sensitivity Analysis

  Tushar Goel, Christoph Maurath - Livermore Software Technology Corporation

  The cost of optimization increases with the dimensionality of the problem irrespective of using metamodels or direct methods. It is recommended to explore the opportunities to reduce the number of variables. One method to reduce the dimensionality is to fix the variables that do not influence the response significantly. ANOVA based on polynomial response surfaces is often used to identify the least important design variables. The global sensitivity analysis, proposed by Sobol, is another very useful technique to reduce the dimensionality. This method can be used with any surrogate model and is often used as a variable screening tool. While the dimensionality reduction based on a single response is widely used, this study presents an easy approach, facilitated by LS-OPT®, to reduce the number of design variables when a system comprising of multiple responses is considered. The benefits of reducing the problem dimensionality are demonstrated using a crashworthiness example.

• Vehicle Dynamic Simulation Using A Non-Linear Finite Element Simulation Program (LS-DYNA)

  G. S. Choi, H. K. Min - Kia Motors Technical Center

  The reason manufacturers invest their time and money in order to improve the performance of dynamic characteristics, fatigue stiffness, NVH and crash safety during the process of vehicle development is directly linked to their competitiveness. Due to the rapid development of the computer CPU and application software, it is possible to perform dynamics analysis and durability design using CAE tools before making a prototype vehicle to reduced time and money in testing and developing a vehicle.

• Vehicle Restraint System Optimization and Robustness Assessment using the Coupling between LS-DYNA, LS-OPT and DEP MeshWorks Software

  C. Goubel (DynaS+)

  Road safety structures are CE (European Commission) marked safety systems which need to be crash tested. Structure performances during the crash tests and the associated rating have a significant marketing impact for the system manufacturer and unfortunately depend on parameters subjected to stochastic variation (raw material mechanical properties, test conditions, vehicle design, …). Numerical simulation has been widely used for several decades to assist in the design of these new road safety devices. Historically, in order to identify a design likely to pass the experimental tests, simulation has mostly been used without taking into account the variability of the modelled system parameters but only its nominal design. However, in too many cases, the great variability of such devices (materials characteristics, ground type, assembly conditions, impact parameters, etc…) leads to unexpected behaviour (and results) and jeopardizes the test validation. In the following sections the full process of one road safety system optimization will be presented starting with the correlation between the numerical model results and the corresponding real crash test results. Then, a design optimization on a reduced model will be performed using an innovative approach based on an advanced use of the DEP MeshWorks morphing capabilities coupled with LS-OPT© and LS-DYNA©. Finally, based on the optimal design found previously, an additional sensitivity study using LS-OPT and LS-DYNA will be conducted to better assess the device robustness and its sensitivity to material characteristics changes. The aim is to enable designers of new systems to better assess the risk of failure when performing the experimental tests required by the standard.

• Vehicle Roof Crush Modelling & Validation

  Mingzhi Mao, E. C. Chirwa,T. Chen - The University of Bolton, UK

  Real roof crush tests, quasi-static or dynamic, have been widely used to evaluate the safety integration of vehicle structure, especially in the USA, where there are specified standards such as FMVSS 208 and 216. Europe is endeavouring to reach the same target for vehicle safety taking into account the different road condition. However, carrying out full experimental tests is shown to be costly and in many cases unrepeatable. That is why the development of good reliable models can be the key to the solution of successful roof crush simulation that predict real world accidents. For this particular paper, the modelling was partially carried out in Radioss FE model and then translated into LS-DYNA3D. The complete model was finalised in LS-DYNA3D, where it was made available for the roof crush simulations. To improve the structural integrity, spotwelds were remodelled and new Nodal_Rigid_Bodies were built-in manually due to the different definitions and interpretations in these two codes. Roof mesh refinements were done in order to remove roof stiff behaviour in some areas and therefore match the roof deformed pattern shown in real test. Local Cartesian coordinate system was established for rigid planes’ spatial position. In addition, time integration algorithms in LS- DYNA3D were also discussed for roof crush prior to performing quasi-static and dynamic simulations on a small European car. Thereafter the results were verified against the real tests which showed very good agreement, especially in the time history crush characteristics. However, despite the force peak values to be nearly the same there is still a small discrepancy between the quasi-static roof crush simulation and its real test characteristic.

• Vehicle Seat Bottom Cushion Clip Force Study for FMVSS No. 207 Requirements

  Jaehyuk Jang (CAE Body Structure Systems General Motors)

  Federal Motor Vehicle Safety Standard (FMVSS) No. 207, "Seating Systems," establishes requirements for seats, their attachment assemblies, and their installation, to support robust design for seat attachment to Body under vehicle impact. General Motors has been continuously improving the CAE procedure for this Safety Standard. This presentation introduces a CAE simulation method that was specifically developed to accurately simulate a deformational behavior of the plastic clip that is installed at seat bottom cushion attachments to the vehicle floor. The focus of this study was on how to precisely predict the separation point in load, if it occurs, so that the design of the attachment can be updated to ensure the success of the respective test. This paper discusses a customized model setup for the clip removal force measurement using *DATABASE_JNTFORC with separation criteria at the latch that successfully enables the model results to match the empirical force data at separation. In this newly developed method, an interface management between three-dimensional seat foam and one-dimensional wireframe elements embedded inside the foam without depending on rigid links is introduced. This method uses *CONSTRAINED_LAGRANGE_IN_SOLID keyword that is primarily intended for modeling Fluid-Structure Interaction (FSI). Its CAE simulation process flow from benchmarking up to a proof run to demonstrate a correlation to its empirical data is also introduced.

• Vehicle Structures Experimental Analyses

  Moisey B. Shkolnikov

  This paper is a summary of previous developments, publications and usage of special strain gages sets (referred to here as experimental finite elements, FEs) in experimental analyses of vehicle structures. The experimental FEs developments were based on Structural Mechanics, Math Statistic theories and experience of their applications in vehicle structures analyses and tests. The summary’s objective is to describe the LS-DYNA® optional participation in experimental analyses by using experimental FEs for confirmation of analytical simulation results. Currently LS- DYNA (and its pre and post processors) have enough capability to use experimental measurement results for analytical results confirmations. However not always LS-DYNA users are familiar with the details of strain gage technology, and experimental specialists are not always familiar with the details of LS-DYNA usage of measured strains. Experimental FEs in LS-DYNA would provide a bridge between those analytical and experimental technologies. LS-DYNA users would be able to generate experimental FEs based on a vehicle structure analytical FEs model simulations results and defining structure’s areas needed the simulation results experimental confirmations. That information and information specifying types of strain gages and rosettes and their locations on a vehicle structure under tests may be provided by the LS-DYNA users to experimental specialists. Based on that information the experimental specialists will conduct the structure tests and provide to the LS-DYNA users the required types and amount of strain gage measurements results.

• Verification and Validation of LS-DYNA for the Transport and Storage of Radioactive Materials

  G. Marchaud, V. Saint-Jean (Areva)

  solutions for radioactive material with the highest levels of safety and security. Transportation and storage casks are designed to comply with stringent regulations. For instance, a cask designed to transport radioactive material may be required to withstand a 9m drop onto a flat unyielding target. AREVA TN performs LS-DYNA analyses to evaluate the crashworthiness of casks and to reduce the number of costly real tests. Such a methodology relies on the capability of the computer code to model the main physical phenomena that occur in a cask and its content when they are subject to a transient mechanical event. The validity of LS-DYNA is confirmed by comparing its results with reference results, for a variety of test cases covering these phenomena. The reference results are obtained either analytically or from real tests. AREVA TN defined specific test cases to validate: - The main constitutive laws suitable for shock-absorbing materials (e.g. woods) and containment vessel materials (namely metals), - The time integration scheme, with a view to the conservation of total energy, - The implementation of geometric nonlinearities (large displacements and rotations), - The correct representation of mass/stiffness distribution (vibrations, rigid-body displacements), - Shockwave propagation, - Energy dissipation in a complex structure composed with components in contact with each other. Such a qualification is performed every time AREVA TN chooses to use a more recent version of LSDYNA. The present paper will focus on a selection of these test cases and present their features as well as their results.

• Verification and Validation of a Three-Dimensional Generalized Composite Material Model

  Canio Hoffarth, Joseph Harrington, Subramaniam D. Rajan (Arizona State University), Robert K. Goldberg, Kelly S. Carney (NASA-GRC, Cleveland), Paul Du Bois (George Mason University), Gunther Blankenhorn (LSTC)

  A general purpose orthotropic elasto-plastic computational constitutive material model has been developed to accurately predict the response of composites subjected to high velocity impact. The three-dimensional orthotropic elasto-plastic composite material model is being implemented initially for solid elements in LS-DYNA® as MAT213. In order to accurately represent the response of a composite, experimental stress-strain curves are utilized as input, allowing for a more general material model that can be used on a variety of composite applications. The theoretical details are discussed in a companion paper. This paper documents the implementation, verification and validation of the material model using the T800-F3900 fiber/resin composite material.

• Verification of a New Fracture Criterion Using LS-DYNA

  Liang Xue, Tomasz Wierzbicki - Massachusetts Institute of Technology

  Several fracture models are available in the material library of LS-DYNA. This paper is concerned with a newly developed constitutive model that covers the full range of plasticity till the onset of fracture. It is understood that the fracture initiation in uncracked solids is an ultimate result of a complex damage accumulation process. Such damage is induced by plastic deformations. A new damage model is proposed to incorporate the pressure sensitivity and the Lode angle dependence through a nonlinear damage rule using a reference fracture strain on a restricted loading path. The onset of fracture is predicted by integrating incremental damage along the actual loading path. In this cumulative fashion, fracture can be predicted for complex loading paths, which are not limited to the restricted loading in which the pressure is constant. This modified model also incorporates the coupling between the damage and the strain hardening function. The new fracture model is implemented to LS-DYNA as a user defined material subroutine. A series of benchmark tests and simulations have been performed to verify this model. The loading situations of these tests cover a wide range of standard laboratory testing, which include uniaxial tension of a round bar, uniaxial tension of a hollow bar and the three-point bending of a rectangular bar. A remarkable agreement between the experimental and numerical results is achieved.

• Verification of Concrete Material Models for MM-ALE Simulations

  Swee Hong TAN, Roger CHAN, Jiing Koon POON and David CHNG (Ministry of Home Affairs, Singapore)

  Although there are many concrete material models in LS-DYNA®, very few appear to be valid for Multi-Material Arbitrary Lagrangian-Euler (MM-ALE) simulations. From a rudimentary point of view, it makes sense at the first instance, that the typical method of verification via simulating cylinder tests in triaxial and/or uniaxial stress states for Lagrangian format should work for MM-ALE as well. This paper shares the experiences gathered from attempts at simulating cylinder tests involving MM-ALE concrete material models. Useful insights were gained and they would form part of the considerations for future work.

• Verification of Concrete Spalling Simulation with Wave Propagation Theory

  Sunao Tokura

  It is well known that spalling failure occurs when concrete walls are subjected to impact loading. This is explained by the fact that the compressive stress wave generated by the impact propagates from the front surface to the back surface and is reflected at the back surface as a tensile stress wave that exceeds the tensile strength of the concrete. Spalling failure is one of the most important failure modes in evaluating the response of concrete structures subjected to impact loading. Ansys LS-DYNA has several capabilities to simulate spalling failure, but whether the depth from the surface where spalling occurs is accurately simulated is an important indicator for predicting the actual response of the structure with high accuracy. Therefore, in this study, the accuracy of the simulation of spalling failure using LS-DYNA was investigated based on the wave propagation theory. As a result, it was confirmed that LS-DYNA could reproduce the behavior of spalling failure with high accuracy.

• Verification of cylindrical interference fits under impact loads with LS-Dyna

  Prof. Dr.-Ing. Helmut Behler, Jan Göbel, M.Eng. - Hochschule Mannheim, Steffen Heute, M.Eng. - Alpha Engineering Services GmbH

  Interference fits are a commonly used means to couple shafts and wheels for example. The usual dimensioning is performed by a static verification. As long as the system geometry is not too complicated and the deformation is assumed to be linear elastic, the interference pressure can easily be calculated with the more familiar solutions of the equations of elasticity. The maximum static contact forces can be calculated together with an assumed coefficient of static friction. In order to investigate whether a cylindrical interference fit provides sufficient stability against slip the real loads have to be known. However in various applications this is not the case and the interference fit is subjected to dynamic loads, especially to impact loads. We simulate a model interference fit that is first axially mounted and later also axially loaded. This is a typical case in hydraulic systems. Similar problems occur in gears, e.g. worm gears, especially if there are reverse torques as in many applications. The crucial number a design engineer seeks is the safety against slip, S. A dimensional analysis shows that S is dependent on the length l of the interference fit, its interference Z, the velocity v and the mass of the impacting body m and the static friction coefficient μ. Altogether we find: S ~ Z l μ v-1 m-0.5. Numerical experiments have shown that the easiest way is to vary the velocity of the impacting body to find the design with minimum safety S = 1. The desired safety can then be achieved by simply changing the parameters. We investigate the influence of different contact types, and find the OSTS contact as optimal for the shaft-hub contact. The same way we consider the NTS contact as optimal for the shaft-impacting body contact. The results also show that the forces due to an impact are huge and that it is not possible to make an appropriate design without a numerical or experimental analysis.

• Verification of cylindrical interference fits under impact loads with LS-Dyna

  Prof. Dr.-Ing. Helmut Behler, Jan Göbel, M.Eng. - Hochschule Mannheim, Steffen Heute, M.Eng. - Alpha Engineering Services GmbH

  Interference fits are a commonly used means to couple shafts and wheels for example. The usual dimensioning is performed by a static verification. As long as the system geometry is not too complicated and the deformation is assumed to be linear elastic, the interference pressure can easily be calculated with the more familiar solutions of the equations of elasticity. The maximum static contact forces can be calculated together with an assumed coefficient of static friction. In order to investigate whether a cylindrical interference fit provides sufficient stability against slip the real loads have to be known. However in various applications this is not the case and the interference fit is subjected to dynamic loads, especially to impact loads. We simulate a model interference fit that is first axially mounted and later also axially loaded. This is a typical case in hydraulic systems. Similar problems occur in gears, e.g. worm gears, especially if there are reverse torques as in many applications. The crucial number a design engineer seeks is the safety against slip, S. A dimensional analysis shows that S is dependent on the length l of the interference fit, its interference Z, the velocity v and the mass of the impacting body m and the static friction coefficient μ. Altogether we find: S ~ Z l μ v-1 m-0.5. Numerical experiments have shown that the easiest way is to vary the velocity of the impacting body to find the design with minimum safety S = 1. The desired safety can then be achieved by simply changing the parameters. We investigate the influence of different contact types, and find the OSTS contact as optimal for the shaft-hub contact. The same way we consider the NTS contact as optimal for the shaft-impacting body contact. The results also show that the forces due to an impact are huge and that it is not possible to make an appropriate design without a numerical or experimental analysis.

• Verification of Sound Absorption Characteristics Constituted Porous Structure

  Toru Yoshimachi, Ryo Ishii, SOL Corporation, Japan;, Kuniharu Ushijima, Naoki Masuda, Tokyo University of Science, Japan;, Takao Yamaguchi, Gunma University, Japan;, Yun Huang, Zhe Cui, Livermore Software Technology Corporation, USA

  This paper presents the verification the level of acoustic solver in LS-DYNA® and availability of LS-DYNA evaluating acoustic issue interior problem. We made sound in a Rectangular empty box made from aluminum and measured sound there by microphone in order to compare the experiment and simulation. We prepare fundamental material as sound absorption and attached it to the Rectangular empty box. In LS-DYNA, The characteristics of the sound absorbing material are considered as acoustic impedance boundary conditions. The analysis result is good agreement with the peak frequency measured in the experiment.

• Verification of the Part-Composite Approach for Modeling the Multi-Layered Structure of a Rolling Truck Tire

  S. Shokouhfar, S. Rakheja (Concordia University)

  Accurate modeling of a truck tire for predicting dynamic characteristics requires an adequate representa- tion of its composite plies. This study compares two approaches in modeling the multi-layered structure of a rolling radial-ply truck tire using LS-DYNA. In the first approach, different layers in the tire structure are modeled using individual elements; whereas, in the second, all layers are represented by a single element with layered configuration managed by the PART_COMPOSITE keyword. Hence, in this article, these tire models are named as the Individual-Element (IE) model versus the Part-Composite (PC) model.

• Vibration Analysis of a Compressor Blade at High Temperature

  Devon Downes, Manouchehr Nejad Ensan (Aerospace Portfolio, National Research Council)

  This paper summarizes the vibration analysis of a stage two T56 compressor blade at high temperature. First, an implicit thermal analysis was performed to elevate the blade’s temperature to 700°C. The output parameters of this analysis were then used as a “pre-stress” condition of the blade prior to starting the vibration analysis. Velocity results obtained using numerical simulations were compared to experimental results. The simulation was able to capture the peak velocity within 10% of the experimental result. This analysis was also used to estimate the peak equivalent stress location under combined vibration and high temperature loading. Increased stress was found around the base of the blade where the physical geometry changed abruptly and where the loading was applied.

• Virtual Ballistic Testing of Kevlar Soft Armor: Predictive and Validated Modeling of the V0-V100 Probabilistic Penetration Response using LS-DYNA®

  Gaurav Nilakantan, Teledyne Scientific & Imaging, Thousand Oaks, CA 91360, USA

  Over 15 years of worldwide research into the ballistic impact modeling of woven aramid fabrics used in soft armor based on yarn-level fabric finite element models has been unable to achieve any quantitatively-predictive and validated capability to predict the V0-V100 probabilistic penetration response of the fabric against various threats. For the first time ever, we demonstrate such a capability and the comprehensive framework behind it that brings together highly focused research across several fronts enabling a close synergistic interplay between experiments, statistical analysis, and finite element modeling. The exemplar scenario chosen to demonstrate this capability comprises a fully-clamped, single-ply, Kevlar S706 plain-weave fabric impacted by two types of 0.22 cal projectiles: a 11-gr sphere and a 17-gr FSP. The fabric model comprises individually-modeled 3D yarns with a user-defined material model. Observed stochastic variability in material properties and testing are mapped into the model to enable probabilistic outcomes. The model accurately predicts the experimental V0-V100 curves for both the 0.22 cal projectiles. The model also captures the spread in projectile residual velocities over the range of penetrating experimental test shots conducted, including variability in projectile exit trajectories.

• Virtual Die Tryout of Miniature Stamping Parts

  Ming-Chang Yang, Tien-Chi Tsai - Metal Industries R&D Center, Taiwan

  The authors would like to present the whole procedure of using dynamic explicit finite element method to aid multi-stage miniature stamping die design. How to cost down and time saving are the key issues for tool maker in Taiwan. It has been applied to many automobile components and metalwork successfully by computer aided design and engineering analysis. In this paper, we dedicated our application of these technologies to small scale stamping parts. The trick of mass scaling for speed up the computation of LS-DYNA and control its effect in dynamic behavior for miniature blank sheet will be described in this paper. Die designers can operate die try out many times during one day on their desk top personal computer for their different processes changed. A mini scale ball bearing retainer stamping part was demonstrated. The history of metal flow and its thickness variation for pre-form stage and finished-form stage in real test were matched with the simulation results. It has been approved that the accuracy of numerical result is good for miniature sheet metal part. By this way, we have saved many try and error tests for die modify and try out in reality.

• Virtual engineering and planning process in sheet metal forming

  Dr. Wolfram Volk, Pierre Charvet - BMW AG

  Nowadays the engineering and planning process in sheet metal forming is fundamentally supported by CAD and CAE systems. Beside the full 3D design process of parts and tools the simulation of sheet metal forming processes has established itself in the last 15 years within standard industrial practises. Nevertheless the virtual engineering and planning consists of more than just CAD and CAE tools. For a coordinated and effective process it is recommended to make use of the so-called process chain model. Therewith the interactions between different technologies or single processes can be taken into account. The process chain “Painted Car Body” consists of geometry and functionality development as well as forming, joining and coating processes. The backbone of a process chain is generally called “Synchroplan” where the main technical and business milestones for the different technologies and development processes are fixed. The challenges for the virtual planning process are response time and accuracy with respect to the Synchroplan milestones. In the early phase of product development it is helpful to make use of standards. These standards give guidelines for the product design process with respect to feasibility and robustness without restricting “engineering freedom” which will enable new styling and technical innovations. These standards are sometimes much more than just single numbers. For repeatable geometry details (door entrance, rear lights etc.) one can define so called meta models if these details can be represented by few parameters. The benefit of these meta models is the quick assessment of parameter combinations with an adequate accuracy. With this argumentation it is clear that an effective and efficient virtual engineering and planning process consists of three major components: - standards for geometry and process technology - fast CAD tool for creation of geometry proposals - effective CAE tool for fast and accurate assessment enabling definition of improvements The more standards are defined and accepted over the whole process chain the less detailed simulations and CAD loops are necessary. Nevertheless realisation of new styling ideas and technological improvements (new materials, improved crash worthiness etc.) always require CAD and CAE support. The backbone of the CAD process at BMW Group is currently the CAD system CATIA V5. All geometry information in the process chain has to be finally delivered in native CATIA V5 data. But especially in the early or so called concept phase of a project it is not necessary for sub processes that all CAD work is done in the backbone system. A typical example is the concept die face for the geometry definition of a forming simulation. With this geometry no physical tool is built and therefore no native CAD data is required. It is more important to realise the ideas and proposals of the engineer as fast as possible with a sufficient accuracy for FE-simulation. Nevertheless the geometric proposals after the engineering loop should be finally available in the CAD system. For the definition of a concept die face several working steps are (typically) necessary: - import of part geometry (ideally with native CAD data) - flange unfolding and lay out of geometry details from following operations - definition of the basic production idea (double part, symmetry, ...) - definition of drawing direction - part preparation (filling of holes, smoothening of boundary, ....) - creation of blank holder - design of addendum - preparation for simulation All these working steps beside the preparation for simulation can obviously be realised also in the standard CAD system. The most time consuming work is the creation of the addendum in comparison to specialised alternative solutions. This is the main reason why currently the concept die faces are not generally designed in CATIA V5. The accuracy and necessary design work for concept die faces strongly depends on the examination objectives. Especially the prediction of surface quality of outer skin panels necessitates much engineering work for the blank holder. Therewith the first contact of the blank with the forming tools is determined which causes sometimes unacceptable skid or impact lines. For the FE-simulation of concept die faces a powerful CAE tool is necessary. Beside of short calculation times an easy applicability is of high interest. Nevertheless one has need for well described complex material models and powerful user interfaces to solve extraordinary boundary value problems, e.g. for the virtual assessment of new forming technologies. LS-DYNA fulfils most of these demands and has a high application rate in research work at universities. In the past, the main objectives of forming simulations were only the assessment of feasibility (e.g. occurrence of necking and wrinkles). Nowadays additional and more complex examinations are possible due to improvements of the simulation systems. Some examples are press force calculation, multi stage forming, spring-back, surface quality, failure prediction for complex strain paths. Many of these applications need an accurate stress calculation. For new material grades like ultra high strength dual phase steels the classical material description is not sufficient anymore. The advantage in competition for automotive companies is the controllability in the virtual planning and engineering process even without having experience of series production. The more accurate the material description in the simulation tools the less problems and scrap rate occur in the production. Normally the first simulation of a concept die face will not lead to a feasible part geometry. In an effective virtual engineering and planning process it is necessary to show the way to feasible and robust production processes. The fast translation of simulation results in geometric proposals is an essential step. The handling of geometry updates is a big challenge for the work with concept die faces. An easy and robust parametric design of the concept die faces is still one of the biggest problems in this context. Even for specialised systems for the creation of concept die faces there is still much room for improvements. Due to this problem we should not restrict ourselves to single software systems from the general viewpoint of BMW Group. It is necessary to define useful interfaces and data formats. Therewith a fruitful competition and a market also for smaller software companies or university spin offs can exist. An example for such an interface is the description of a forming process based on a concept die face. It is necessary to define links on the tool geometry and sheet material, the forming direction and additional information like cam positions and directions. Tool meshes and detailed material data should not be included in this interface. The big advantage of intelligent interfaces is the possibility to combine different CAD and CAE systems as well as the possibility for fast modification loops. We expect a higher innovation velocity with widely accepted interfaces due to a wider market and more competitors.

• Virtual engineering and planning process in sheet metal forming

  Dr. Wolfram Volk, Pierre Charvet - BMW AG

  Nowadays the engineering and planning process in sheet metal forming is fundamentally supported by CAD and CAE systems. Beside the full 3D design process of parts and tools the simulation of sheet metal forming processes has established itself in the last 15 years within standard industrial practises. Nevertheless the virtual engineering and planning consists of more than just CAD and CAE tools. For a coordinated and effective process it is recommended to make use of the so-called process chain model. Therewith the interactions between different technologies or single processes can be taken into account. The process chain “Painted Car Body” consists of geometry and functionality development as well as forming, joining and coating processes. The backbone of a process chain is generally called “Synchroplan” where the main technical and business milestones for the different technologies and development processes are fixed. The challenges for the virtual planning process are response time and accuracy with respect to the Synchroplan milestones. In the early phase of product development it is helpful to make use of standards. These standards give guidelines for the product design process with respect to feasibility and robustness without restricting “engineering freedom” which will enable new styling and technical innovations. These standards are sometimes much more than just single numbers. For repeatable geometry details (door entrance, rear lights etc.) one can define so called meta models if these details can be represented by few parameters. The benefit of these meta models is the quick assessment of parameter combinations with an adequate accuracy. With this argumentation it is clear that an effective and efficient virtual engineering and planning process consists of three major components: - standards for geometry and process technology - fast CAD tool for creation of geometry proposals - effective CAE tool for fast and accurate assessment enabling definition of improvements The more standards are defined and accepted over the whole process chain the less detailed simulations and CAD loops are necessary. Nevertheless realisation of new styling ideas and technological improvements (new materials, improved crash worthiness etc.) always require CAD and CAE support. The backbone of the CAD process at BMW Group is currently the CAD system CATIA V5. All geometry information in the process chain has to be finally delivered in native CATIA V5 data. But especially in the early or so called concept phase of a project it is not necessary for sub processes that all CAD work is done in the backbone system. A typical example is the concept die face for the geometry definition of a forming simulation. With this geometry no physical tool is built and therefore no native CAD data is required. It is more important to realise the ideas and proposals of the engineer as fast as possible with a sufficient accuracy for FE-simulation. Nevertheless the geometric proposals after the engineering loop should be finally available in the CAD system. For the definition of a concept die face several working steps are (typically) necessary: - import of part geometry (ideally with native CAD data) - flange unfolding and lay out of geometry details from following operations - definition of the basic production idea (double part, symmetry, ...) - definition of drawing direction - part preparation (filling of holes, smoothening of boundary, ....) - creation of blank holder - design of addendum - preparation for simulation All these working steps beside the preparation for simulation can obviously be realised also in the standard CAD system. The most time consuming work is the creation of the addendum in comparison to specialised alternative solutions. This is the main reason why currently the concept die faces are not generally designed in CATIA V5. The accuracy and necessary design work for concept die faces strongly depends on the examination objectives. Especially the prediction of surface quality of outer skin panels necessitates much engineering work for the blank holder. Therewith the first contact of the blank with the forming tools is determined which causes sometimes unacceptable skid or impact lines. For the FE-simulation of concept die faces a powerful CAE tool is necessary. Beside of short calculation times an easy applicability is of high interest. Nevertheless one has need for well described complex material models and powerful user interfaces to solve extraordinary boundary value problems, e.g. for the virtual assessment of new forming technologies. LS-DYNA fulfils most of these demands and has a high application rate in research work at universities. In the past, the main objectives of forming simulations were only the assessment of feasibility (e.g. occurrence of necking and wrinkles). Nowadays additional and more complex examinations are possible due to improvements of the simulation systems. Some examples are press force calculation, multi stage forming, spring-back, surface quality, failure prediction for complex strain paths. Many of these applications need an accurate stress calculation. For new material grades like ultra high strength dual phase steels the classical material description is not sufficient anymore. The advantage in competition for automotive companies is the controllability in the virtual planning and engineering process even without having experience of series production. The more accurate the material description in the simulation tools the less problems and scrap rate occur in the production. Normally the first simulation of a concept die face will not lead to a feasible part geometry. In an effective virtual engineering and planning process it is necessary to show the way to feasible and robust production processes. The fast translation of simulation results in geometric proposals is an essential step. The handling of geometry updates is a big challenge for the work with concept die faces. An easy and robust parametric design of the concept die faces is still one of the biggest problems in this context. Even for specialised systems for the creation of concept die faces there is still much room for improvements. Due to this problem we should not restrict ourselves to single software systems from the general viewpoint of BMW Group. It is necessary to define useful interfaces and data formats. Therewith a fruitful competition and a market also for smaller software companies or university spin offs can exist. An example for such an interface is the description of a forming process based on a concept die face. It is necessary to define links on the tool geometry and sheet material, the forming direction and additional information like cam positions and directions. Tool meshes and detailed material data should not be included in this interface. The big advantage of intelligent interfaces is the possibility to combine different CAD and CAE systems as well as the possibility for fast modification loops. We expect a higher innovation velocity with widely accepted interfaces due to a wider market and more competitors.

• Virtual Modeling of Forming Processes in Metal Packaging Industry

  I. Moldovan, M. Linnepe, L. Keßler (thyssenkrupp Steel Europe), M. Köhl (thyssenkrupp Packaging Steel)

  Nowadays the finite element method is technical standard in many industry sectors such as automotive manufacturing. Thus the material behaviour for steel applications in this field is extensively developed. In packaging industry, virtual approaches in process- and product development are more the exception. Instead, the cost-intensive and time-consuming trial-and-error method is commonly used to approach the limits of the material specific formability. Packaging steel is characterised by thicknesses between 0.1 to 0.49 mm and thyssenkrupp Packaging Steel offers strengths between 180 to 750 MPa. However, with tougher process limits, especially due to continuous thickness reduction, this method has its limitations. Speaking of material saving and optimisation simulation tools are gaining increasingly importance. In contrast to the automotive industry, established approaches for material characterisation do not exist and not all norms cover that low thickness range for sheet materials. The following work gives an indication of current possibilities for material characterisation of thin steel sheet. A completed validation ensures process and product designing with available material models.

• Virtual Modelling of Motorcycle Safety Helmets: Practical Problems

  Alessandro Cernicchi, Ugo Galvanetto, Lorenzo Iannucci - Imperial College London

  Motorcycle helmets are safety devices that can be optimised to perform better in different impact configurations. It is not easy to determine the mechanical properties of a particular model of helmet which maximise its effectiveness in real impact conditions and it is not surprising that most helmet producers use empirical design procedures and assess the effectiveness of their products by carrying out numerous experimental impact tests. The application of advanced computational techniques (i.e. Finite Element Method) to the study of the mechanical behaviour of helmets has been conducted with a variable degree of success in several cases. The use of virtual methods clearly provides a superior flexibility during the design process due to the simplicity by which the model is modified and retested. This work is an attempt to clarify modelling aspects encountered in helmet virtual testing, such as mesh dependency of the results, the influence of retention system on the response and composite shell modelling. A Finite Element model of a commercially available helmet has been developed and impact tested reproducing the test conditions prescribed by the ECE 22.05 standards. Particular emphasis has been given to the analysis of fibre reinforced plastic helmets, which are currently under further development, due to their superior performance. The results have been compared with experimental data and possible reasons for discrepancies have been analysed.

• Virtual product development in the Digital Engineering Center: Greater innovative capacity through interdisciplinary organization and automation

  C. Woll (GNS Systems)

  While the traditional development cycle of "design-build-test" often lasted several years, today it is imperative to bring innovations to market readiness with simulation-driven design and digital twin in shorter time spans. Virtual tests on vehicles make a significant impact in effectively reducing development times and costs. Companies must master two fundamental challenges for their efficient use: on the one hand, complex and time-intensive engineering tasks have to be mastered quickly. On the other hand, solutions are increasingly required that organise the complex product development across organizational units. The Digital Engineering Center, an engineering workplace in the cloud, meets these challenges.

• Virtual Prototyping for Safer Product Development: Integrated Marine Propulsion and Steering System Example

  M. Perillo, D. Schiavazzi, V. Primavera (EnginSoft SpA), D. Sacchi (ZF Marine)

  Abstract ZF Marine’s POD Drive is an innovative marine integrated propulsion and steering system with increased performances compared to traditional shaftline systems in term of efficiency, manoeuvrability, ease of control and dimensions. The system comprises an inboard/outboard transmission and double motor electrical steering pod system equipped with counter-rotating propellers. An electronic control system manages one or more PODs and each of them rotates independently, depending on maneuver typology, speed and turning circle. Due to their manoeuvring orbital functions ̧ operating conditions and under hull position, underwater impact risk assessment is demanded as important safety design requirement. To decode any potential impact scenario into its design specification is a technical challenge concerning the capability to predict structural consequences. A new design methodology, that incorporates statistical approaches to investigate non deterministic factors that affect design impact conditions (e.g. impact velocity and angle, debris mass and stiffness, etc.) and Virtual Prototyping tools is developed to increase safety reliability of the design choices respect to accidental underwater impacts. Sensitivity analyses, parametric numerical models with increasing complexity and different simulation methods are employed during design process to design different sacrificial components able to break or to shear below the hull for minimizing damage to POD system or to the primary boat structures. Complete 3D numerical simulations are performed through LS-DYNA and full scale experimental tests are carried out either to validate design process and numerical models or to compare numerical and experimental results.

• Virtual Proving Ground – A CAE Tool for Automotive Durability, Ride & Handling and NVH Applications

  Arthur Tang, Nasser Tamini, David Yang - Engineering Technology Associates, Inc.

  The Virtual Proving Ground approach has been developed for simulation of dynamic nonlinear events as applied to automotive durability, ride & handling and noise/vibration/harshness applications. This finite element analysis technique provides a unique method to create and analyze vehicle system models, capable of including vehicle suspensions, powertrains and body structures in a single simulation. Through the development of this methodology, event-based simulations of the vehicle performance, over a given three-dimensional road surface can be performed. The development of methodologies and approaches for performing this type of analysis will be discussed, which make up a "Virtual Proving Ground" environment. Case studies will be presented to show the application of this methodology to a full vehicle system for vehicle durability, ride & handling and noise/vibration/harshness applications. The results of this case study will highlight the potential applications of this approach, as well as the challenges associated with the method.

• Virtual Reality in Crash Simulation

  Friedhelm Birk - 3Dims GmbH Frankfurt, Germany

  Since simulation of complex things like crashing a car becomes more precise and more affordable its only natural that one wants to analyze the results in a way a humans nature can intake complexe data best: visually.

• Virtual Reality Visualization (VRV) of Realistic Weapons Effects Predicted Using LS-DYNA

  David W. Nicholson – University of Central Florida, Orlando,, Ricardo F. Moraes - Major of the Army of Brazil, Eduardo Divo, Brian Cahill – Dual Incorporated

  A prototype of low cost system is described for visualization of realistic weapons effects experienced by targets undergoing blast and impact, to be used in training of personnel for livefire environments. The system is based on integrating two tools: (a) The Finite Element (FE) impact code LS-DYNA (b) A Virtual Reality Visualization (VRV) system The VRV system was recently developed by DUAL Incorporated of Lake Mary, FL in partnership with the University of Central Florida (UCF). It consists of a PC- level graphics workstation, a head mounted display, motion trackers, a multi-degree of freedom mouse, drivers and a software toolkit, all of which have been established at DUAL and UCF.

• Virtual ROPS and FOPS Testing on Agricultural Tractors According to OECD Standard Code 4 and 10

  D. Hailoua Blanco, C. Martin, A. Ortalda (EnginSoft S.p.A)

  The Roll Over Protection Structure (ROPS) and Falling Object Protective Structure (FOPS) are key safety features in agricultural and forestry tractors in order to avoid or limit risks to the driver in case of roll over or falling objects during normal use. The Organization for Economic Co-operation and Development (OECD) in an effort to improve operator’s safety in Agricultural and Forestry Tractors has set up harmonized testing procedures for ROPS and FOPS systems. The current OECD Codes for tractors relate to several features of performance. In particular, Code 4 and 10 are related to the strength of protective structure in case of roll over and falling objects, respectively [1-2]. On the one hand, Code 4 foresees a sequence of loadings that the protection system has to withstand until the prescribed energy or force is satisfied. The magnitude of the required energy and forces depend upon the reference mass of the tractor. In addition to successfully resist the loading sequence, the ROPS has to guarantee a clearance zone during any part of the tests around the seat index point (SIP), where the operator is placed. By fulfilling all these conditions, the structure is classed as a roll-over protective structure in accordance with the OECD Code 4. On the other hand, Code 10 implies a series of object drop tests from a height to develop a specific energy. Likewise, the clearance zone shall not be entered by any part of the protective assembly or the impacting object itself to pass the test. In light of the complex testing scenarios, numerical simulations with LS-DYNA ® were carried out to virtually assess the performance of a ROPS and FOPS system designed by the Italian tractor manufacturer. As a matter of fact, ROPS and FOPS simulations turned out to be very useful to understand the behavior of the protection system subjected to complex loading and get valuable insights into performance. The main goal of the simulations was to virtually test the tractor according to the Code 4 and 10 prior to official test approval and, if necessary, introduce the necessary structural changes in order to successfully pass the ROPS and FOPS tests.

• Virtual testing developments of the LS-DYNA® WorldSID 50th dummy model

  Alexander Schif, Yupeng Huang, Sebastian Stahlschmidt

  In 2024 the European New Car Assessment Programme (Euro NCAP) Virtual Testing Crashworthiness (VTC) procedure for far-side impact is introduced. The LS-DYNA DYNAmore WorldSID 50th dummy model will be part of this procedure. Separate qualification criteria must be satisfied for the WorldSID model. They are specified in Technical Bulletin TB043-1 [1]. LS-DYNA DYNAmore WorldSID 50th version 8 will be the first model with the official certificate to satisfy all the defined criteria of TB043-1. TB043-1 includes three different stages of certification. Normative dummy requirements are checked in the first stage. Component level tests of head-neck and lumbar spine represent the second stage. The last stage includes a new full dummy sled test scenario representing the far-side load case. The dummy model must pass all three stages to be fully certificated.

• Virtual Testing of Curved Vehicle Restraint Systems

  B. Fröhlich (Bundesanstalt für Straßenwesen)

  Real crash tests against vehicle restraint systems according to the standard EN 1317 are performed with straight barriers. The objective of this study is to investigate the performance of a curved barrier. A validated model of a real tested vehicle restraint system was subjected to a modification. The straight barrier in the original simulation model was modified with different constant curvatures. Virtual crash tests with straight and differently curved barriers were carried out with the same boundary conditions as the real test. The results concerning the behavior of the vehicle and the barrier were compared. The expected consequences of a barrier in a curve are the following: The vehicle is contained by the barrier. The dynamic deflection of the barrier during the crash is lower than the dynamic deflection of the unmodified straight barrier. The acceleration severity increases due to the curvature of the barrier.

• Virtual Testing Protocols and LS-DYNA – Pre and Post Processing Solutions in the Oasys LS-DYNA Environment

  Alasdair Parkes, Rory Bradshaw

  The Oasys LS-DYNA Environment is a key part of many LS-DYNA workflows, used to ensure quality models and results. The introduction of virtual testing crashworthiness (VTC) protocols is changing how CAE teams create and process LS-DYNA crash models and poses several challenges for CAE workflows. Good correlation is moving from beneficial to mandatory, and we can no longer rely on conservative assumptions. The format and quality of outputs is increasingly important to meet the requirements of regulatory bodies. CAE teams will need to work more with physical test data, and safety teams will need to work more with simulation data – how do we improve collaboration and processing? How can we manage large amounts of data for virtual testing?

• Virtual Tool Commissioning using LS-DYNA Functional Mock-up Interface

  S. Heiland, L. Penter, S. Ihlenfeldt (TU Dresden), L. Klingel, F. Jaensch, A.Verl (University of Stuttgart), C. Schenke (Fraunhofer IWU)

  The commissioning of forming tools includes the mechanical spotting of the active surfaces and the identification of suitable actuator set values. It represents a time-consuming and expensive step in the tool development process. A major cause for the necessity of this manual die spotting is the elastic compliance of press and die that results in geometric deviations between predicted and produced part geometry as well as the control characteristics and the resulting accuracy of the drives. The interactions between the machine and the forming process can be computed numerically. An integration of simulation models that includes the machine behavior into the tool development process offers potential for time and cost savings for die manufacturers and machine operators.

• Virtual Try Out and Process Optimization for an Innovative Conic Poles Production Concept

  A. Anglani, G. Papadia - University of Lecce, Italy, A.Del Prete - Altair Engineering s.r.l.

  This paper describes how the production Process for conic poles has been reviewed in order to provide innovative solutions for the forming process which has been considered the most critical operation. Finite Element Analysis using an explicit code has provided a virtual way to investigate possible solutions evaluating advantages or disadvantages before that any prototype tool has been developed. More than one solution was possible, FEA has given the chance to evaluate the more promising one which was based on a different forming philosophy, that is the usage of profiling forming, which has an innovative aspect if it is applied on conic shapes like in this case. Tools shapes and process parameters were tuned through a massive usage of numerical simulations. The defined innovative solution allows to cut the production times of a considerable amount with an higher quality for the final product.

• Virtual Vehicle Company Overview.pdf
• Visions and Latest Developments in Dynaform

  Arthur Tang, Jeanne He - Engineering Technology Associates, Inc.

  DYNAFORM has been evolved from a Draw Die analysis tool to a Die System analysis tool kits. As the simulation technology and computer resources have been growing rapidly, more demands emerges from different stage of the product and process development sector. Stamping simulation technology is facing more challenges. Based on LS- DYNA ® implicit and explicit solver, DYNAFORM provide simulation tools that support not only the incremental analysis for validation of Draw Die face design, also provides an one-step analysis based cost estimating tool (BSE), Die Face Design tool (DFE) and Die structure analysis, motion transfer and scrap shedding Analysis. DYNAFORM helps the product and process development cycle and makes them more efficient and reliable. Evolving into a process based simulation tool is the future of DYNAFORM. Upgrading the user interface to be flexible for customization and supporting script function are the focus of the next generation DYNAFORM. This paper will also discuss our visions and the future development of DYNAFORM.

• Visual-Environment Integrated Pre and Post Environment for LS-DYNA

  Shivakumara H Shetty, Velayudham Ganesan, Suthy C Sivalingam - ESI Group

  Visual-Environment (VE) is an open collaborative engineering environment framework or platform called as Open VTOS (Virtual Try-Out Space). VE is an integrated suite of solutions, which has different contexts seamlessly linked for Crash and Safety, Durability, NVH and others. The applications of interest for supporting LS-DYNA based processes are: Visual-Crash DYNA (VCD)-a pre processor for LS-DYNA, Visual-SAFE-an advanced pre-processor for safety features, Visual-Mesh a general purpose mesher, Visual-Viewer (VVI)-a general purpose plotting and simulation application, Visual, Visual-Process Executive-an application for CAE process customization and repetitive tasks automation. These are some of the contexts available in VE but focused to support LS-DYNA. Globalization, new regulations and changes in technologies are influencing the simulation life cycle. These changes are driving the pre and post processing environments for remarkable improvement in productivity, usability and innovative approaches. This paper describes the key features of Visual-Environment 4.0 for LS-DYNA and usefulness of these features in Crash and Safety simulation with productivity examples and process automation.

• VisualDSS CAE Data Management and Decision Support System for Simulation Life Cycle Management

  Velayudham Ganesan, Suthy C Sivalingam, Shivakumara H Shetty - ESI Group, Daniel Dooge - ESI North Americas

  Simulation industry has matured enough to carry out the design iterations using just the simulation results without relying on expensive prototype testing. Such simulation approaches have drastically reduced the product development lead time, cost and product failures. Engineers and managers spend most of their time on non engineering activities searching for information, learning simulation tools and workflows, hackneyed repetitive simulations, manual communication and manual simulation data management. The integrated simulation management system such as VisualDSS® (Visual Decision Support System) helps to outwit the current performances of simulation by addressing such non engineering areas of simulation. VisualDSS is a simulation lifecycle management system from ESI’s Visual-Environment suite which aims at providing end-to-end decision support for the simulations such as LS-DYNA® by providing integrated multi disciplinary simulation management features such as simulation data management, compute model management, simulation automation and workflow management, knowledge capture and reuse, simulation project management, results and audit trails processing, smart search and queries, inter enterprises simulation collaboration management and much more. This enables the enterprises to make better decisions, increase the simulation productivity, reduce the project lead time and cost, eliminate the simulation assets loss and improve the simulation reliability. This paper describes the application of VisualDSS in the CAE industry catering multi domain simulation and data management with the objective of supporting decision making process.

• Visualising Vehicle Platoon Aerodynamics Using ICFD in LS-DYNA

  Edward Pettitt, Max Resnick (ARUP)

  Since the fuel crisis in the 1970s, platooning of vehicles has been considered as a method of reducing fuel consumption and improving traffic congestion. Up till now, research has primarily considered homogeneous platoons with varying separation distances. Furthermore, the basis of much of the work so far has been experimental instead of computational and so fluid flow interactions between the platooning vehicles are not well understood. The Incompressible Computational Fluid Dynamics (ICFD) solver in LS-DYNA® provides a powerful method to simulate flow interaction around a body and produce data to be used in understanding the aerodynamic behaviour. This paper shows some of the capabilities of LS-DYNA in visualising fluid flow around complex bodies when in platooning formation. Of interest in this paper is the variation of geometry of the vehicles within a platoon with a set separation distance. This paper considers the ability of LS-DYNA to analyse fluid flow interaction between multiple bodies and explores how this could be of use for future platooning research.

• Visualization of Pareto Optimal Fronts for Multiple Objectives with D-SPEX

  Katharina Witowski, Marko Thiele - DYNAmore GmbH, Tushar Goel - Livermore Software Technology Corporation

  Most engineering optimization problems require multi-objective optimizations that have no unique optimum because the objectives often conflict. LS-OPT 3.3 offers the capability to simultaneously compute many Pareto optimal solutions using a multi-objective genetic algorithm. The optimization post processing tool D-SPEX provides advanced features to visualize these Pareto optimal solutions and to approximate the Pareto optimal front using the moving least squares method. In addition, the moving least squares method may now be used in D-SPEX as an additional option for building response surfaces as well as for the computation of virtual histories.

• VMAP enabling interoperability in integrated CAE simulation workflows

  K. Wolf, P. Gulati (Fraunhofer SCAI) G. Duffett (NAFEMS)

  With the progress in CAE simulation leading to more complicated and integrated workflows, data control and transfer becomes essential. This is extremely important in the manufacturing industry where complicated simulation workflows are necessary in tracking material changes throughout the manufacturing proclete software interoperability.

• Volume-Averaged Stress States for Idealized Granular Materials using Un­bonded Discrete Spheres in LS-DYNA

  M. T. Davidson, J. H. Chung, V. Le (Bridge Software Institute), H. Teng, Z. Han (LSTC)

• VOLVO TECHNOLOGY VEHICLE STRUCTURAL OPTIMIZATION ENVIRONMENT

  Gunnar Björkman,Jimmy Forsberg - Volvo Technology, Jan Engström - SCH Incubator AB

  With the ever increasing capability in computer power, optimizing a full vehicle structure including most of the crash load cases will be a real possibility in the near future. For example, the Cell chip used in PS3 or the availability of recent GPU of high end PC graphics cards delivers 100 – 1000 GFLOPS. The bottleneck in this scenario will not be the computer power, instead the problem will be how to feed the computers with models and input decks to analyze in a reliable and stable way with little or no manual interventions. At Volvo Technology, we have, in different research and internal projects, developed a Vehicle Structural Optimization Environment that has the capability to enable the use of global optimization, in the development and evolution of vehicle structure. This environment integrates and manages the analysis software, the optimizer, our Linux cluster together with its queuing system, the model and concept generator, and finally the management of all generated models and analysis results. Currently we are using LSdyna for crash and static analysis, LSopt for controlling the optimizations and AML for creating models and input decks. An important factor in this environment is to have a stable model and input deck generator, without any manual interaction, capable of generating input decks for analysis for all types of concept that is of interest. Except for just changing thicknesses we may want to: find the most effective material to use, both from a weight and a cost perspective, determine the best layout for tailor welded blanks, change the cross section dimensions, find needed stiffeners or investigate new way of subdividing the design in parts. As an example, a global optimization of a BIW, including approximately 100 design variables, analyzing the Euro NCAP crash cases for five stars, handling, comfort and cost, running approximately 10-12 iterations for the optimization, will result in approximately 2500-3000 crash analysis, 1500-2000 eigenvalue analysis, and 4000

• VPG Solutions Using MotionView

  Michael White - Altair Engineering

  The MotionView® product has been extended in version 6.0 to support LS-DYNA input and output. MotionView is a template based pre and post processor with a long history in the automotive industry. An example of an automotive handling event, and several examples of durability events will be shown. A vehicle model with a complete powertrain (engine and transmission) will be simulated, to demonstrate the “plug and play” templated model methods used by MotionView. The Altair Swingset benchmark problem will be run in LS-DYNA, and the results of this will be shown, to illustrate a consumer products application of the tool.

• Vulnerability of Bridge Piers to Impact by Heavy Vehicles

  Sherif El-Tawil - University of Michigan

  My talk presents work undertaken to investigate the effects of vehicle collision on bridge piers. Inelastic transient finite element simulations are used to investigate the structural demands on bridge piers generated during such events, which have occurred in the past, sometimes with catastrophic consequences. Two different types of trucks and two different bridge/pier systems are used in the simulations. The approach speeds for the trucks range from 55 to 135 kph. Various quantities of interest are extracted from the finite element results and used to develop a better understanding of the vehicle/pier crash process and to critique current specifications addressing such events.

• Warm Forming Simulation of 7075 Aluminium Alloy Tubes Using LS-DYNA

  G. D’Amours, J.F. Béland - National Research Council Canada

  The demand for lightweight tubular products, designed specifically for transportation and recreational applications, is currently on the rise. In general, performance increase and energy cost reduction are the main reasons justifying the need for these specialty products. Hence, to reach these goals, both industries are turning to complex-shaped tubes for various types of applications. However, high performance aluminium tubes, such as 7075 alloy, provide very low formability characteristics at ambient temperature and do not have the ductility needed for hydroforming-based applications. A 1,000-ton hydroforming press, located at the Aluminium Technology Centre, was equipped with a + 600 oC heating die designed for such tube and sheet forming applications. The die has 10 separate heating zones that can be adjusted independently. The first application was employed to form a tubular bicycle component. To achieve this, a thermo-mechanical model was developed using LS-DYNA to determine the tube temperature distribution around the heating zones. To this end, conduction, convection, radiation and contact heat transfer conductance were the physical phenomena considered in the thermal model. Prior to developing the mechanical model, a heating chamber was designed and fabricated. Tube samples underwent in-chamber testing using a servo-hydraulic system at various temperatures and strain rates. With the results, an elastic viscoplastic temperature-dependent material constitutive law was used to properly predict tube strains and stresses. The finite-element model can predict the necessary tube temperature and gas pressure during the heat-based forming process, thus enabling to obtain optimum formability of 7075 aluminium alloy tubes.

• WATER IMPACT: EXPERIMENTAL TESTS AND NUMERICAL SIMULATIONS USING MESHLESS METHODS

  Marco Anghileri, Luigi Castelletti, Edoardo Francesconi - Politecnico di Milano, Italia

  The outcomes of a research focusing on water modelling and fluid-structure interaction, are here presented. A number of water impact drop tests using a typical aircraft skin panel were performed. The tests were numerically reproduced modelling the fluid region using the two meshless methods implemented in LSTC/LS-Dyna 971: the Smoothed Particle Hydrodynamics and the Element Free Galerkin method. The accuracy of the models was evaluated referring to the data collected in the tests.

• Wear Analysis of Machinery Components in Buildings

  John Puryear, Ben Harrison (ABS Group), Lynsey Reese (NAVFAC Engineering and Expeditionary Warfare Center)

  Buildings incorporate a variety of mechanical systems for the convenience of occupants. These systems may include machinery for heavy lifting. Excessive wear in the machinery components can result in unanticipated maintenance and loss-of-service costs. The Wear Analysis utility in LS-PrePost® was used to quantify component wear over the service life for a vertical lift system. Candidate materials for a roller and jamb geometry were modeled. The wear predictions were then used to evaluate the candidate material combinations. The methodology provided by Jernberg and Borvall was followed for the analysis. Due to the relative low loading rate in the problem (i.e. much less than the loading rate in automotive impact), the contact force history between the roller and plate was calculated using implicit dynamics. This force history was the input into the Wear Analysis utility using the dynain file from *INTERFACE_SPRINGBACK_LSDYNA, and Archard’s wear law was used to calculate wear depth. The wear law returns wear volume as a function of surface hardness, normal force (as calculated in the implicit analysis), sliding distance and wear coefficient. The above methodology was applied to three combinations of materials for the roller and jamb plate selected from hardened steel, stainless steel and aluminum. *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE_MORTAR was necessary for the implicit calculation to converge. Static and dynamic coefficients of friction (COFs) were obtained from the CRC Handbook; the decay constant from static to dynamic COF was from Stembalski. In this paper, the remaining details of the analysis are discussed, including the constitutive models used for the metals. The wear predictions are provided. Finally, recommendations are made for increasing confidence in the calculations and convenience of the calculation method.

• WEB-CENTRIC LS-DYNA

  Henry H. Fong HPC Marketing – Enterprise Systems Products Sun Microsystems

  The Internet has changed the way business is done – and High Performance Computing (HPC) is no exception. Many firms have launched “dot-com” software to facilitate B2B collaboration, outsource jobs, provide engineering services, or exchange data with suppliers and partners. Recently, however, hundreds of dot-coms have failed, and many high-tech companies have laid off thousands of workers. Now what? The term ASP (application service provider) has become popular in the past several years. ASPs deliver and manage applications and services remotely for multiple users – either through the Internet or a private network. An ASP owns the relationship with the end-user customer. Security tops the list of customers’ concerns. Hundreds of ASPs have sprung up, but most of these (e.g., Exodus, Qwest, Corio, EDS, Applicast, etc.) host computing services for commercial applications rather than technical ones. This paper introduces some basic concepts in portal supercomputing and ASPs, and suggests future directions LSTC and its worldwide distributors may wish to consider to web-enable LS-DYNA to make it accessible to a wider engineering community.

• Web-Centric LS-DYNA - Development of a Technical Computing Portal

  Dan Fraser, Youn-Seo Roh, Henry H. Fong - Sun Microsystems, Inc.

  The development of a Technical Computing Portal (TCP) for monitoring and managing of LS- DYNA runs is described. The Sun TCP is a new collaborative tool for High Performance and Technical Computing. It facilitates access, workload distribution, job monitoring, and management of LS-DYNA and other technical application jobs in a heterogeneous computing environment. It can be easily customized by LS-DYNA users, and by LSTC and its distributors. TCP is based on Sun's iPlanet Portal Server, Java, and Sun Grid Engine technologies.

• Wood and wood products - linking multiscale analysis and structural numerical simulations

  Karin Hofstetter, Josef Eberhardsteiner, Reinhard Stürzenbecher, Christoph Hackspiel - Vienna University of Technology

  Wood is one of the oldest construction materials known to man. Over thousands of years it has been mainly used in a craft framework, so that current design rules are often based on experience and tradition. The scientific knowledge about the material behavior is often surprisingly poor. In order to exploit the extraordinary ecological potential of the material and to enable its structural use also in an industrial framework, improved material models are required. Modern timber construction is characterized by increasing demand of two- and three dimensional bearing components. Dimensioning and design of such sophisticated structures require powerful material models for numerical simulation tools such as the finite element (FE) method. Moreover, the large variability of the macroscopic material properties has to be understood and suitably described to prevent exaggerated safety factors resulting in an uneconomic over-dimensioning of timber members. In order to understand the variability of macroscopic properties of solid wood and the underlying phenomena and to suitably describe them in material models, the hierarchical microstructure of the material has to be considered. At sufficiently small length scales universal constituents common to all wood species and samples as well as universal building principles can be identified. Namely, lignin, hemicellulose, cellulose, and water are such tissue-independent universal constituents with common mechanical properties across the diverse wood species at the molecular level. They build up cell walls resembling fiber-reinforced composites, which are arranged according to a honeycomb pattern. A mathematical formulation of the univeral building principles results in a multiscale micromechanical model for wood which links microstructural characteristics of individual wood samples to macroscopic mechanical characteristics of these samples. Homogenization techniques are employed for this purpose. In particular, the composite structure of the wood cell wall motivates application of continuum micromechanics for estimation of its elastic properties. At the cellular scale, plate-type bending and shear deformations dominate the mechanical behavior, which are more suitably represented by a unit cell approach. Formulation of the localization problem corresponding to the multiscale homogenization scheme allows determination of strain estimates at smaller length scales for given macroscopic loading. Quadratic strain averages (so-called ‘second-order estimates’) over microstructural components turned out to suitably characterize strain peaks in these components. Combination of estimates for such averages with microscale failure criteria delivers predictions for macroscopic elastic limit states. As for solid wood, experimental investigations indicate that wood failure is initiated by shear failure of lignin in the wood cell wall. This can be suitably described mathematically by means of a von Mises- failure criterion. The multiscale models for wood stiffness and elastic limit states are validated by comparison of model predictions for stiffness and strength properties with corresponding experimental results across a multitude of different wood species and different samples. The small errors of the model predictions underline the predictive capabilities of the micromechanical model. For example, the mean prediction errors for the elastic moduli and the shear moduli related to the three principal material directions L, R, and T are each below 10 %. The capability of micromechanical approaches to link macroscopic properties to microstructural characteristics renders such approaches also very appealing for wood products. In this paper, models for a representative of strand-based products, namely the Veneer Strand Board (VSB), as well as for a representative of solid wood-based products, namely the DendroLight panel, are shown. VSB consists of large-area, flat and slender strands with uniform strand shape and dimensions and is typically built up of several layers with different strand orientations. The high-quality strand material results in increased stiffness and strength of the board compared to conventional strand and veneer- based panels. The multiscale model for VSB spans three scales of observations: the strand material, a homogeneous board layer, and the multi-layer board. Continuum micromechanics is applied first in order to estimate the elastic properties of a homogeneous board layer from the stiffness of the strands, their shapes, and their orientations. In the second step, effective stiffness properties of a multi-layer panel are determined by means of classical lamination theory. Thereby, the stacking sequence, the orientation of the principal material directions of the single layers, and the density variation across the board thickness are taken into account. Model validation is again based on independent experiments. Results of tests on specially produced homogeneous boards as well as inhomogeneous boards with a well defined vertical density distribution show a good agreement with corresponding model predictions. This underlines the capability of the model for estimation of the stiffness of strand-based engineered wood products from microstructural features and renders it a powerful tool for parameter studies and product optimization. DendroLight is a three-layered lightweight panel consisting of thin outer layers of solid wood or particle board and a middle layer made up of small cells with webs inclined by an angle of 45° facing alternatively upwards and downwards. The periodic microstructure motivates application of the unit cell method for prediction of the mechanical behavior of this panel. As for plane periodic media, macroscopic unit curvature states are considered as loadings of the unit cell in addition to macroscopic unit strain states. In particular, effective in-plane stiffnesses and bending stiffnesses are obtained. For the purpose of model validation, several panel samples were produced by hand and tested in tension. The experimental results show a good agreement with corresponding stiffness predictions by the model. The multiscale model has already been successfully employed for product characterization and further product development. Since wood is a naturally grown material, it shows growth irregularities, primarily knots and site-related defects. Knots result in a pronounced reduction of stiffness and strength of wooden boards. Due to the highly anisotropic material behavior of wood, the influence of the grain orientation on the mechanical properties of a board is very pronounced and results in high variability in strength and stiffness of structural timber. The latter is a major difficulty in solid wood utilization and brings about the need for wood grading. This motivates investigation of the effects of knots on the mechanical behavior of boards by means of physically-based numerical simulations. In particular, the FE method is combined with sophisticated models for the fiber course and the material behavior. For the description of the local fiber course around a knot, a mathematical algorithm based on a fluid flow approach and polynomial functions fitted to the annual ring course is employed. The algorithm is evaluated at every integration point of the FE model and yields the local three-dimensional fiber orientation there. With respect to the mechanical material behavior, the previously described micromechanical model for solid wood is used, enabling consideration of local variations of microfibril angles or chemical composition of the wood tissue in the vicinity of knots. First results obtained with the numerical simulation tool indicate its capability to estimate the stiffness and strength reduction of wood boards in consequence of knots. On the whole, micromechanical models provide accurate estimates for the mechanical properties of wood and wood products in a fully three-dimensional and orthotropic framework. Also various couplings, e.g. between moisture transport and mechanical behavior, are suitably captured by these models. This makes these models highly valuable for structural simulations, whose predictive and also descriptive capabilities are often limited by the lack of suitable input data or the poor accuracy of available data. Hence, micromechanical modeling activities are expected to support structural analyses of wood structures, but also optimization of processes in wood drying technology.

• Wood and wood products - linking multiscale analysis and structural numerical simulations

  Karin Hofstetter, Josef Eberhardsteiner, Reinhard Stürzenbecher, Christoph Hackspiel - Vienna University of Technology

  Wood is one of the oldest construction materials known to man. Over thousands of years it has been mainly used in a craft framework, so that current design rules are often based on experience and tradition. The scientific knowledge about the material behavior is often surprisingly poor. In order to exploit the extraordinary ecological potential of the material and to enable its structural use also in an industrial framework, improved material models are required. Modern timber construction is characterized by increasing demand of two- and three dimensional bearing components. Dimensioning and design of such sophisticated structures require powerful material models for numerical simulation tools such as the finite element (FE) method. Moreover, the large variability of the macroscopic material properties has to be understood and suitably described to prevent exaggerated safety factors resulting in an uneconomic over-dimensioning of timber members. In order to understand the variability of macroscopic properties of solid wood and the underlying phenomena and to suitably describe them in material models, the hierarchical microstructure of the material has to be considered. At sufficiently small length scales universal constituents common to all wood species and samples as well as universal building principles can be identified. Namely, lignin, hemicellulose, cellulose, and water are such tissue-independent universal constituents with common mechanical properties across the diverse wood species at the molecular level. They build up cell walls resembling fiber-reinforced composites, which are arranged according to a honeycomb pattern. A mathematical formulation of the univeral building principles results in a multiscale micromechanical model for wood which links microstructural characteristics of individual wood samples to macroscopic mechanical characteristics of these samples. Homogenization techniques are employed for this purpose. In particular, the composite structure of the wood cell wall motivates application of continuum micromechanics for estimation of its elastic properties. At the cellular scale, plate-type bending and shear deformations dominate the mechanical behavior, which are more suitably represented by a unit cell approach. Formulation of the localization problem corresponding to the multiscale homogenization scheme allows determination of strain estimates at smaller length scales for given macroscopic loading. Quadratic strain averages (so-called ‘second-order estimates’) over microstructural components turned out to suitably characterize strain peaks in these components. Combination of estimates for such averages with microscale failure criteria delivers predictions for macroscopic elastic limit states. As for solid wood, experimental investigations indicate that wood failure is initiated by shear failure of lignin in the wood cell wall. This can be suitably described mathematically by means of a von Mises- failure criterion. The multiscale models for wood stiffness and elastic limit states are validated by comparison of model predictions for stiffness and strength properties with corresponding experimental results across a multitude of different wood species and different samples. The small errors of the model predictions underline the predictive capabilities of the micromechanical model. For example, the mean prediction errors for the elastic moduli and the shear moduli related to the three principal material directions L, R, and T are each below 10 %. The capability of micromechanical approaches to link macroscopic properties to microstructural characteristics renders such approaches also very appealing for wood products. In this paper, models for a representative of strand-based products, namely the Veneer Strand Board (VSB), as well as for a representative of solid wood-based products, namely the DendroLight panel, are shown. VSB consists of large-area, flat and slender strands with uniform strand shape and dimensions and is typically built up of several layers with different strand orientations. The high-quality strand material results in increased stiffness and strength of the board compared to conventional strand and veneer- based panels. The multiscale model for VSB spans three scales of observations: the strand material, a homogeneous board layer, and the multi-layer board. Continuum micromechanics is applied first in order to estimate the elastic properties of a homogeneous board layer from the stiffness of the strands, their shapes, and their orientations. In the second step, effective stiffness properties of a multi-layer panel are determined by means of classical lamination theory. Thereby, the stacking sequence, the orientation of the principal material directions of the single layers, and the density variation across the board thickness are taken into account. Model validation is again based on independent experiments. Results of tests on specially produced homogeneous boards as well as inhomogeneous boards with a well defined vertical density distribution show a good agreement with corresponding model predictions. This underlines the capability of the model for estimation of the stiffness of strand-based engineered wood products from microstructural features and renders it a powerful tool for parameter studies and product optimization. DendroLight is a three-layered lightweight panel consisting of thin outer layers of solid wood or particle board and a middle layer made up of small cells with webs inclined by an angle of 45° facing alternatively upwards and downwards. The periodic microstructure motivates application of the unit cell method for prediction of the mechanical behavior of this panel. As for plane periodic media, macroscopic unit curvature states are considered as loadings of the unit cell in addition to macroscopic unit strain states. In particular, effective in-plane stiffnesses and bending stiffnesses are obtained. For the purpose of model validation, several panel samples were produced by hand and tested in tension. The experimental results show a good agreement with corresponding stiffness predictions by the model. The multiscale model has already been successfully employed for product characterization and further product development. Since wood is a naturally grown material, it shows growth irregularities, primarily knots and site-related defects. Knots result in a pronounced reduction of stiffness and strength of wooden boards. Due to the highly anisotropic material behavior of wood, the influence of the grain orientation on the mechanical properties of a board is very pronounced and results in high variability in strength and stiffness of structural timber. The latter is a major difficulty in solid wood utilization and brings about the need for wood grading. This motivates investigation of the effects of knots on the mechanical behavior of boards by means of physically-based numerical simulations. In particular, the FE method is combined with sophisticated models for the fiber course and the material behavior. For the description of the local fiber course around a knot, a mathematical algorithm based on a fluid flow approach and polynomial functions fitted to the annual ring course is employed. The algorithm is evaluated at every integration point of the FE model and yields the local three-dimensional fiber orientation there. With respect to the mechanical material behavior, the previously described micromechanical model for solid wood is used, enabling consideration of local variations of microfibril angles or chemical composition of the wood tissue in the vicinity of knots. First results obtained with the numerical simulation tool indicate its capability to estimate the stiffness and strength reduction of wood boards in consequence of knots. On the whole, micromechanical models provide accurate estimates for the mechanical properties of wood and wood products in a fully three-dimensional and orthotropic framework. Also various couplings, e.g. between moisture transport and mechanical behavior, are suitably captured by these models. This makes these models highly valuable for structural simulations, whose predictive and also descriptive capabilities are often limited by the lack of suitable input data or the poor accuracy of available data. Hence, micromechanical modeling activities are expected to support structural analyses of wood structures, but also optimization of processes in wood drying technology.

• Wood-steel structure for vehicle restraint systems

  C. Goubel, M. Massenzio, S. Ronel - Université de Lyon

  Certain roadside safety barriers are structures made of steel and wood. This kind of structure is currently in fashion in location where the safety equipments need to be discreet (mountains, countryside). In Europe, to be installed on the roadside, the vehicle restraint systems have to pass two crash tests, as defined in the European standard EN1317. Our aim is to develop a dynamic model of the multi material structure in order to understand and optimize the safety barriers i.e. to define the best association of the mechanical properties of both materials. The first part of this paper concerns three point bending experimental tests at different energy levels. These laboratory tests were used as a basis for the evaluation of a material constitutive law. Then, a numerical parametric study which takes into account the variation of moisture content and temperature, as observed in the experiment, will be exposed. After that, a model of a roadside safety barrier and a procedure based on variation of failure modes analysis will be presented in order to correlate the numerical model to the real crash test results. Finally, a parametric study, concerning wood mechanical properties, will be performed in order to check the effect of this variation on the device performances.

• Workflow-based Material Characterization for LS-DYNA® in d3VIEW

  Suri Bala, LSTC and d3VIEW;, Paul Du Bois; Independent Consultant;, Shashank Dhanakshirur, d3VIEW

  Abstract Characterization of material models involves a series of operations, verifications and eventual use of developed material card in simulation models. LS-DYNA presents over 300 material models and provides a wide-variety of materials that can be modeled. In this paper, we hope to present a workflow based material characterization in d3VIEW for Metals, Polymers, Cellular Solids, and Elastomers. A simple workflow example will be included to demonstrate the process of importing data from an Uni-Axial test, create a preliminary material card, run LS-DYNA simulations to optimize the post-necking behavior using LS-OPT®, and generation of the LS-DYNA keyword that incorporates parameters identified in LS-OPT. With the workflow capability, we hope to significantly reduce the time and effort involved in developing material cards for LS-DYNA.

• WorldSID 5% Dummy Model Development in Cooperation with German Automotive Industry

  Sebastian Stahlschmidt, George Dumitru, Yupeng Huang, Ulrich Franz (DYNAmore GmbH)

  The paper describes the methodology used to develop the PDB and FAT Dummy models. The models are used by almost all OEMs and restraint system suppliers to enhance the passive safety performance of their vehicles. Nevertheless, the PDB is still launching new projects to further enhance the predictability of the ES-2, ES-2re, BioRID-II and WorldSID models. This paper presents the current state of a new project to develop the WorldSID 5% model. The project is still in definition phase but there are first results available of the Modell. The test database generated to build and validate the models is described as well as the performance of the current development release.

• WorldSID 50th The Next Generation Side Impact Dummy

  Bhavik Shah, Yi Liu - FTSS

• WorldSID 50th vs. ES-2 A Comparison Based on Simulations

  Sebastian Stahlschmidt, Alexander Gromer - DYNAmore GmbH, Matthias Walz - Daimler AG

  For testing side impact performance of vehicles two recent male-sized dummies are available. Currently only the ES-2(re) is used in regulations and consumer test. It is expected that the WorldSID will be used for some load cases as substitute or in addition to the ES-2(re). Since only limited experience with the WorldSID is available, simulation is a ideal tool to face the upcoming challenge. The comparison employs detailed finite element dummy models of the ES-2(re) and WorldSID which have been developed in cooperation with the German Association for Automotive Research (FAT) and the Partnership for Dummy Technology and Biomechanics (PDB) during the last years. The paper compares the behavior of the dummy in selected body regions. It showcases in different load cases if the experiences gained with the ES-2(re) can be used to design a vehicle for tests with the WorldSID.

• WorldSID Dummy Model Development in Cooperation with German Automotive Industry

  Alexander Gromer, Sebastian Stahlschmidt - DYNAmore GmbH, Peter Schuster - Dr. Ing. h.c. F. Porsche AG

  The paper describes methodology used to develop the PDB WorldSID model. The test database generated to build and validate the models is described, as well as the design process of a new barrier shape to validate the model in respect to the new FMVSS 214 oblique pole test. Finally, the performance of the current development release is presented.

• Worst-Case Topology Optimization

  Imtiaz Gandikota, Willem Roux, Guilian Yi

  This paper presents a worst-case design approach for the multidisciplinary topology optimization of an automotive hood design. The study considers the impact of a pedestrian’s head against the hood, static loads, and the minimum weight of the hood – all required to meet general design code requirements in automobile industry. Among the design code requirements of the hood design, the biggest challenge is to handle hundreds of head impact locations specified in the Euro NCAP pedestrian testing protocol, due to the high computational expense of hundreds and thousands of structural analyses demanded in the structural optimization. To overcome this challenge, we accordingly introduce a general framework for the worst-case topology optimization which investigates the worst impact locations on the hood by evaluating the maximum head injury criterion and the maximum deflection of the hood separately, reducing the burden to consider multiple disciplines simultaneously at hundreds of impact locations all at once. At the end, these worst impact locations are combined with a static load case and formulated into a single multidisciplinary design optimization problem that needs only tens of structural analyses per iteration for numerical gradients computation, enabling the proposed design framework suitable for large scale topology optimization problems.

• X760 Bumper Automation and Optimization Process

  T. Zeguer (Jaguar Land Rover)

  Currently the bumper system is developed through a wide variety of individual virtual test methods, the majority of which also have to be verified with physical testing. This paper will describe a new process that produced a one combined virtual process to encompass the full bumper as a system development method by creating One model for a bumper as one system with multiple attributes and requirements and using only one code “ LS-DYNA and LS-OPT”.

• XFEM and EFG Cohesive Fracture Analysis for Brittle and Semi-Brittle Materials

  Yong Guo, C.T. Wu - Livermore Software Technology Corporation

  The finite element analysis of dynamic fracture in solids and structures is challenging due to the modeling of arbitrary crack growth in the continuum domain. The well-known mesh size and mesh orientation dependences add more difficulties into the analysis of this type of problems. In this presentation, we are going to introduce two numerical methods in modeling the dynamic fracture in brittle materials for solid and structures in LS-DYNA®. Both methods were developed by Belytschko and his group [1, 14] and were based on a strong discontinuity approach combined with cohesive forces for the crack initiation and propagation. In EFG method, a visibility method is utilized to define the cracks in the solids and a fast transformation method [18] is applied to handle the boundary conditions in the cracked media. The XFEM method is implemented to model the dynamic fracture in structures. The XFEM method can be viewed as a combination of level sets method and partition of unity method [15] in the description of cracks.

• Yield Locus Exponent Modelling of Packaging Steel for an Optimized Simulation of Limited Dome Height Experiments

  F. Knieps, I. Moldovan, B. Liebscher, M. Köhl (thyssenkrupp), M. Merklein (IMT)

  In packaging steel forming processes, conditions in-between plane strain and biaxial tension are mostly relevant as they lead to failure in deep drawing applications and characterize e.g. the process of the rivet forming in easy-open end applications. To receive precise simulation results in finite element analysis, it is important to consider an accurate modelling of the yield locus in this area. Complex anisotropic yield functions like e.g. Yld2000-2d which was proposed by Barlat and is implemented in LS-DYNA using keyword *MAT_133 do not consider the characterization of this area and maintain an uncertain variable by the yield locus exponent.

• Zoning Method for Efficient Material Properties Calculation

  J. Kronsteiner and E. Kabliman, Leichtmetallkompetenzzentrum Ranshofen GmbH, AIT Austrian Institute of Technology GmbH, Lamprechtshausenerstr. 61, 5282 Braunau am Inn - Ranshofen, AUSTRIA.

  When material models are enhanced by calculating additional effects such as microstructure evolution for every Gauss point and time step, considerable numerical effort must be expected. Interfacing third-party software from within user defined material subroutines can even be more time consuming. In many applications, however, considerable parts of the material domain give similar results. Strain, strain rate and temperature are the most important properties for the material behavior. During the thermo-mechanical processing such as rolling and especially extrusion, material deformation is concentrated in small areas. This means that strain, strain rate and thus temperature remain almost constant for large parts of the material during most of the simulation runtime.