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15th International LS-DYNA Conference

Detroit, 2018

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  • *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.

  • 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 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 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 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 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 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 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 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 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 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 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 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 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.

  • 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®)

  • 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.

  • 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 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

  • 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.

  • 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.

  • 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 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.

  • 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.

  • 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.

  • 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.

  • 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 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).

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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 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 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 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 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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 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 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).

  • Experience with Material and Fracture Modeling at FCA US LLC
  • 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…).

  • 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.

  • 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.

  • 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.

  • 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 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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 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 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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

  • 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® 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® 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’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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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 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 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 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 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 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 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 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®.

  • 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-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-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 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

  • 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 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.

  • 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 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 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 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 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.

  • 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 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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 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.

  • 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 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 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.

  • 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.

  • 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.

  • 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 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 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 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.

  • 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.

  • 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®.

  • 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.

  • 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 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.

  • 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 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 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 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 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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 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 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 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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].

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.