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9th International LS-DYNA Conference

A Brittle Damage Model: Implementation into LS-DYNA and Application to Normal Plate-on-Plate Impact
Martin N. Raftenberg - U.S. Army Research Laboratory
A brittle damage model developed by M. A. Grinfeld was implemented in the LS-DYNA finite element code and applied to the simulation of normal plate-on-plate impact. The model introduces a state variable measure of damage that evolves in proportion to the elastic strain energy. The model degrades the elastic shear modulus in proportion to the state variable’s current level. The implementation procedure by means of the LS-DYNA user- material ...
A Constitutive Formulation for Polymers Subjected to High Strain Rates
S. Kolling, M. Feucht - DaimlerChrysler AG
A. Haufe - Dynamore GmbH
P.A. Du Bois - Consulting Engineer
Reliable prediction of the behavior of structures made from polymers is a topic under considerable investigation in engineering practice. Especially, if the structure is subjected to dynamic loading, constitutive models considering the mechanical behavior properly are still not available in commercial finite element codes yet. In our paper, we present a new constitutive law for polymers which recovers important phenomena like necking, ...
A Coupled Thermal and Mechanical Model of Sliding Wear
S. S. Akarca, W. J. Altenhof, A. T. Alpas - University of Windsor, Canada
Sliding wear of aluminum alloys induce plastic deformation below the contact surfaces even at light loads. Experimental evidence exists for damage accumulation in the form of nucleation of voids and microcracks around the second phase particles in the material layers adjacent to the contact surface. Crack propagation at a certain depth below the surface may lead to the creation of long and thin wear debris particles. The objective of this ...
A Grid-based Adaptive Scheme for the Three-Dimensional Forging and Extrusion Problems with the EFG Method
H. S. Lu, C. T. Wu - Livermore Software Technology Corporation
Procedures to adaptively refine meshes are emerging as an important tool for improving accuracy and efficiency in large deformation and fracture analysis. Comparing to the mesh- based adaptive method, the grid-based adaptive mesh-free method has several built-in advantages including naturally conforming in shape functions, smoothed interpolations in surface construction and state variable transfer, and the results are less sensitive to ...
A High Strain Rate Model with Failure for Ice in LS-DYNA
Kelly S. Carney - NASA Glenn Research Center
David J. Benson - University of California
Paul Du Bois
Ryan Lee - The Boeing Company
Modeling the high velocity impact of ice was a requirement in the safety calculations for the return-to-flight of the Space Shuttle on July 26, 2005. Ice, however, is not a common structural material and commercial finite element programs didn't have any appropriate models. A phenomenological model with failure was developed to match experimental ballistic tests. The model has a relatively small number of material constants, most of which ...
A Mesh Refinement Study on the Impact Response of a Shuttle Leading-Edge Panel Finite Element Simulation
Karen E. Jackson, Edwin L. Fasanella - US Army Research Laboratory, VTD
Karen H. Lyle - NASA Langley Research Center
Regina L. Spellman - NASA Kennedy Space Center
A study was performed to examine the influence of varying mesh density on an LS-DYNA simulation of a rectangular-shaped foam projectile impacting the space shuttle leading edge Panel 6. The shuttle leading-edge panels are fabricated of reinforced carbon-carbon (RCC) material. Nine cases were executed with all possible combinations of coarse, baseline, and fine meshes of the foam and panel. For each simulation, the same material properties ...
A New Way for Multi-piece and Multi-hit Fragment Impact Simulation Using LS-DYNA
Xudong Xin - Karagozian and Case
The kinetic feature of weapon fragment is many small masses traveling at extremely high velocities and scattering radially from the explosion center. To simplify the fragment impact analysis, people often convert the fragment momentum into a triangular pressure load with very high magnitude and very short duration, and apply the load directly onto the target. This method may over- or under-predict the impact response due to the complicacy ...
A Numerical Investigation into the Injury Potential of Three-year-old Children Seated in Forward Facing Child Safety Seats During Side Impact Crashes in Far Side Configurations
Qian Wang, Tanya Kapoor, William Altenhof - University of Windsor
Andrew Howard - The Hospital for Sick Children
This research focuses on the injury potential of children seated in forward facing child restraint seats during side impact crashes. Side dynamic sled tests were conducted by NHTSA using the existing FMVSS 213 seat fixture oriented at both 90° and 45° relative to the motion of the sled buck. A half sine pulse and a scaled FMVSS 213 pulse were used in the tests. All the tests were conducted at a test velocity of 32 km/h (20 mph) and a peak ...
A Numerical Model for Tri-Axially Braided Composites Under High Velocity Soft Projectile Impact
Jingyun Cheng, Wieslaw K. Binienda - The University of Akron, Akron OH
A simplified methodology has been developed for modeling 2D tri-axially braided composite plates impacted by a soft projectile using an explicit nonlinear finite element analysis code LS-DYNA. Fiber preform architecture is modeled using shell elements by incorporating the fiber preform architecture at the level of integration points. The soft projectile was modeled by an Equation of State (EOS). An arbitrary Lagrangian-Eulerian (ALE) ...
A Simplified Approach for Strain-Rate Dependent Hyperelastic Materials with Damage
D.J. Benson - University of California
S. Kolling- DaimlerChrysler AG
P.A. Du Bois - Consulting Engineer
Simulation of rubber-like materials is usually based on hyperelasticity. If strain-rate dependency has to be considered viscous dampers are added to the rheological model. A disadvantage of such a description is time- consuming parameter identification associated with the damping constants. In this paper, a tabulated formulation is presented which allows fast generation of input data based on uniaxial static and dynamic tensile tests at ...
A Simulation-Driven System Design Methodology with Manufacturing Constraints
Kaushik Sinha - DaimlerChrysler Research and Technology
This paper presents a holistic simulation-driven system design methodology considering multiple performance objectives, performance constraints including formability criterion defined herein, using a genetic algorithm based multi-objective optimization software GDOT, developed in-house. This tool treats multiple objective functions separately without combining them in any form. A decision-making criterion is subsequently invoked to select ...
A Study on a Multi-Disciplinary Optimization Method for the PMP
Soon-Young Seo, Jae-Woo Jeong, Dong-Hyeob Cho, Hyuk Kim - Samsung Electronics Co. Ltd.
In the mobile electronic appliances market, the feature of products is getting smaller, thinner and more multi- functional. Therefore, mobile products are easily damaged from drop/impact and thermal cycling load. To make them more reliable under these conditions, the junction area between chips and PCB should be designed to bear up under drop/impact. And the heat caused by main chip (Memory & DMB channel chip) should be dissipated as quickly ...
A User-Defined Element Interface in LS-DYNA v971
Thomas Borrvall - Engineering Research Nordic AB
The user-defined features in LS-DYNA are powerful tools that allow users in academia or industry to verify research results in the context of general and complicated finite element applications. Implementation work concerns only the special field of interest, and there is no need for the comprehensive task of developing and maintaining the complete finite element software. One of the new user-defined features in LS-DYNA v971 is ...
Accurate Prediction of Projectile Residual Velocity for Impact on Single and Multi-Layered Steel and Aluminum Plates
M. Raguraman and A. Deb - Indian Institute of Science, Bangalore
The present paper deals with the simulation of impact of jacketed projectiles on thin to moderately thick single and multi-layered metal armor plates using explicit finite element analysis as implemented in LS-DYNA. The evaluation of finite element modeling includes a comprehensive mesh convergence study not previously reported in literature, using both shell and solid elements for representing single-layered mild steel target plates. It is ...
Advanced Modeling and Drop Simulation With New Features of LS-DYNA
Jason Wu
Phone drop simulation is an important application of LS-DYNA in electronics industry. The application has been widely used in all leading companies to produce electronic handsets, like Nokia, Motorola, and Samsung. Since more new features complemented in 970 version of LS-DYNA, phone modeling and drop simulation strategy has changed a lot to obtain more accurate and quick results. This paper introduces new methods, and recent development of ...
Advances in the Measurement and Modeling of Plastics for Impact Simulations
Hubert Lobo - DatapointLabs
High strain-rate properties have many applications in the simulation of automotive crash and product drop testing. These properties are difficult to measure. Previously, we described a novel inferential technique for the measurement of the properties of polycarbonate. In this paper, we demonstrate that the technique appears to work for a variety of polymers. We also show that plastics exhibit different kinds of high-strain rate behaviors. It ...
Alternative Models of the Offset and Side Impact Deformable Barriers
Dr. Tore Tryland - Hydro Automotive Structures
The deformable barriers consist mainly of honeycomb blocks with highly anisotropic behaviour. These parts are made from several layers with aluminium foil that is glued and stretched to form the honeycomb structure. Simple compression tests show high stiffness and strength when the cell structure is folded while both stiffness and strength are significantly lower when the deformation mode is mainly bending of the thin foil. Remember that the ...
An Assessment of the Robustness of the European Pedestrian Leg Impact Test Using LS-OPT and LS-DYNA
Tim Keer - Arup
The automotive safety community is currently facing the challenge of new pedestrian impact requirements, introduced in Europe in 2005. These requirements necessitate considerable changes to the vehicle front end (bumper system, hood and fenders). LS-DYNA models of the pedestrian impactors (head, upper leg and leg) are an important tool for analysis of the various tests that comprise the new requirements. One of the criticisms of the current ...
An Efficient Shell Element Based Approach to Modeling the Impact Response of Fabrics
Ali Shahkarami, Reza Vaziri - The University of British Columbia, Canada
An efficient shell element based computational model is developed to capture the mechanical response of fabrics. The approach considers a single yarn crossover as the basic building block (unit-cell) of the fabric panel and uses a specially formulated shell element within LS-DYNA to capture the essential features of the membrane response of this unit-cell accounting for both geometrical and material characteristics of the yarns. The shell ...
An Investigation on the Roll-Over Crashworthiness of an Intercity Coach, Influence of Seat Structure and Passenger Weight
Kadir Elitok, Dr. Mehmet A. Guler, Bertan Bayram - Product Development Dept., TEMSA A.S.
Dr.-Ing. Ulrich Stelzmann - CADFEM GmbH
A roll-over event is one of the most crucial hazards for the safety of passengers and the crew riding in a bus. In the past years it was observed after the accidents that the deforming body structure seriously threatens the lives of the passengers, thus the roll-over strength has become an important issue for bus and coach manufacturers. Today the European regulation “ECE-R66” is in force to prevent catastrophic consequences of such roll-over ...
An Objectivity Algorithm for Strain Softening Material Models
Mauricio V. Donadon, Lorenzo Iannucci - Imperial College London
Predictive techniques for the analysis and design of metallic or composite components and structures subject to severe loading can lead to significant mesh sensitivity if cracking or tearing or penetration occurs. This is especially important for composite materials in which the material has an elastic brittle response with little or no plastic behaviour, in which energy could be dissipated. Hence, the full potential use of composite in the ...
Analysis of Extended End-Plate Connections Under Cyclic Loading Using the LS-DYNA Implicit Solver
Ashish Bhargava, W.M. Kim Roddis, Dhafer Marzougui, Pradeep K. Mohan - The George Washington University
Moment-Resisting Frames (MRF’s) are widely used as lateral-force resisting systems in buildings. Their successful performance depends on the behavior of their moment-resisting beam-column connections. In regions at risk for earthquakes, MRF’s need to resist large cyclic forces and displacements. A variety of beam-column connections are used in practice. Most, including end plate connections, are designed assuming the MRF seismic capacity is ...
Application of Dynamic Relaxation in Thermo-Elastic Structural Analysis of Highway Pavement Structures
Samir N. Shoukry, Gergis W. William, Mourad Riad - West Virginia University
This paper describes the application of the dynamic relaxation technique implemented in LS-DYNA in analyzing large transportation structures as dowel jointed concrete pavements under the effect of temperature variations. The main feature of the pavement model is the detailed modeling of dowel bars and their interfaces with the surrounding concrete using extremely fine mesh of solid elements, while in the bridge structure, it is the detailed ...
Application of New Concrete Model to Roadside Safety Barriers
Akram Abu-Odeh - Texas Transportation Institute
The subject of roadside safety has been seeing a healthy growth in the use of nonlinear finite element analysis in designing and analyzing roadside hardware systems. Some factors that helped researchers include the expanded capabilities of LS-DYNA commercial finite element code, the availability of several public domain vehicle models and the availability of material models explicitly built and modified for roadside safety applications. One ...
BioRID II Dummy Model Development -- Influence of Parameters in Validation and Consumer Tests
S. Stahlschmidt, B. Keding, U. Franz - DYNAmore GmbH, Germany
A. Hirth - DaimlerChrysler AG, Germany
Whiplash injuries frequently occur in low speed rear crashes. Many consumer and insurance organizations use the BioRID II dummy, to assess the risk of whiplash injuries in car accidents. An LS-DYNA model of the BioRID II dummy has been developed by DYNAmore GmbH in cooperation with the German Automotive Industry. In the consortium a huge effort has been made to build a test database for the development of the FE-dummy. This paper describes ...
Bird Strike Modeling Using a New Woven Glass Failure Model
Lorenzo Iannucci, Mauricio Donadon - Imperial College London
The bird strike impact problem is an increasing menace to the composite aerospace designer, especially since more aerospace components are being manufactured from composite materials. The LS-DYNA FE code is often used to model such an event as it can accurately represent the bird material behaviour and the contact between the bird and the structure. However, numerical simulations are usually accompanied by a parallel testing programme to ...
Bird Strike Simulation for BA609 Spinner and Rotor Controls
Cheng-Ho Tho, Michael R. Smith - Bell Helicopter Textron Inc.
Bird strike incidents are not uncommon and cost the U.S. civil aviation industry approximately $495 millions and 631,341 hours of downtime annually [1]. The development test to meet the bird strike certification requirements is very costly and time-consuming. This paper presents the bird strike analysis using the Arbitrary Lagrangian- Eulerian (ALE) technique in LS-DYNA for the BA609 spinner and rotor controls assembly shown in Figure 1. ...
CAE Correlation with Test for Door Slam in Nonlinear Dynamic Stress and Fatigue Life Analysis
Guangtian Gavin Song, Rana Sanghera, Surya Yerva, Hamid Keshtkar - DaimlerChrysler Corporation
In automotive industry, CAE fatigue life analysis is very important in durability evaluation and product optimization to dramatically reduce the design period and minimize the expensive durability testing. In the past time, CAE fatigue life analysis is constrained to the linear stress based methodology in the local strain approach. Generally, the linear stress based methodology is stress analysis with linear material properties. Contact ...
Calibration and Experimental Validation of LS-DYNA Composite Material Models by Multi Objective Optimization Techniques
Stefano Magistrali - Omega Srl, Research and Innovation Centre
Marco Perillo - EnginSoft SpA
Experimental quasi-static tensile and impact tests were conducted over two different types of composite laminates and four different types of sandwich laminates, in order to evaluate their basic mechanical characteristics and energy adsorption capability. The second phase of this research work approaches and resolves the calibration of the mechanical parameters included into the LS-DYNA composite material models. This calibration starts and ...
Comparison of LS-DYNA and NISA in Solving Dynamic Pulse Buckling Problems in Laminated Composite Beams
Haipeng Han, Farid Taheri - Dalhousie University, Canada
In this paper the dynamic pulse buckling of laminated composite beams was analyzed using LS-DYNA and another widely used commercial FE code, namely NISA (Ver.12), developed by EMRC (Engineering Mechanics Research Corp). Two types of impact loadings that could induce dynamic pulse buckling of composite beams were analyzed. The first one was a force applied to the structure in a very short duration (i.e., an impulse load). The other one was ...
Considerations for LS-DYNA Workflow Efficiencies in an HPC Linux Environment
Stanley Posey - HPC Applications Development
Manufacturing industry and research organizations continue to increase their investments in structural analysis and impact simulations such that the growing number of LS-DYNA users continues to demand more from computer system environments. These LS-DYNA workflow demands typically include rapid single job turnaround and multi- job throughput capability for users with diverse application requirements in a high-performance computing ...
Crashworthiness Simulation Using Coupled Meshfree/Finite Element Formulations in LS-DYNA
Hui-Ping Wang, Ye-Chen Pan, Yi-Pen Cheng - General Motors Corporation
This paper demonstrates applications of a coupled meshfree/finite element solver of LS-DYNA in the analysis of crashworthiness components. Two examples are employed in the study. The first one is a European side impact dummy component test problem. It is used to show the robustness of the coupled meshfree/finite element solver in handling large deformation since the finite element analysis of this problem fails due to numerical instability ...
Damage Evolution and Energy Absorption of FRP Plates Subjected to Ballistic Impact Using a Numerical Model
L.J. Deka, S.D. Bartus, U.K. Vaidya - University of Alabama at Birmingham
High velocity transverse impact to laminated fiber reinforced composites is of interest in military and structural applications. Damage evaluation of the targets during impact based upon experimental work can be prohibitively expensive. However recent advances in the field of numerical simulation provide a means of predicting the performance characteristics of layered materials for ballistic protection. There is however, limited ...
Demand Driven Side Impact Restraint System Development Method
Gary Owen - Autoliv
This paper describes a demand driven product development method that applies a synergetic combination of numerical simulation and physical test techniques to guide the development of side impact restraint systems and associated simulation procedures and physical test devices.
Development and Implementation of an Advanced User Material Model for UHMWPE
J.S. Bergström, A.E. Bowden - Exponent, Inc
C.M. Rimnac - Case Western Reserve University, USA
S.M. Kurtz - Drexel University, USA
Ultra-high molecular weight polyethylene (UHMWPE) is a semi-crystalline polymer with excellent strength, impact resistance, and abrasion resistance. These mechanical properties have led to extensive use of UHMWPE as a bearing material in total joint replacements. In order to accurately capture the experimentally observed response of this important polymer we have developed a new advanced material model—the Hybrid Model (HM). ...
Development and Validation of a Headform Impactor Finite Element Model with Application to Vehicle Hood Design for Pedestrian Protection
Costin Untaroiu, Jaeho Shin, Jeff Crandall, Scott Crino - University of Virginia
Head injuries are the most common cause of pedestrian deaths in car-to-pedestrian collisions. To reduce the severity of such injuries, international safety committees have proposed subsystem tests in which headform impactors are impacted upon the car hood. In the first part of the paper, the development and validation of an adult headform impactor finite element (FE) model is presented. The skin material model was assumed as viscoelastic and ...
Development of Aluminum Honeycomb Model Using Shell Elements
Shigeki Kojima - Toyota Technical Development Corporation, Japan
Tsuyoshi Yasuki - Toyota Motor Corporation, Japan
This paper describes a new finite element modeling method of aluminum honeycomb using shell elements. It is our new modeling method that cell size of honeycomb structure is enlarged to keep minimum mesh size, and compressive strength is controlled by thickness of shell elements. New modeling was applied to an offset deformable barrier model, and full vehicle crash analysis was performed. The result of offset frontal collision analysis with a ...
Development of an Energy Absorbing End Terminal for Open Box Beam Guardrail
Nauman M. Sheikh, Roger P. Bligh, D. Lance Bullard, C. Eugene Buth, Dean C. Alberson, Akram Y. Abu-Odeh, Hayes E. Ross Jr. - Texas Transportation Institute
An energy absorbing end terminal was developed for use with the European box beam guardrail system. The European box beam rail sections have an open architecture that is different from what is used in North America. The overall design effort utilized finite element simulation, individual component testing using the bogie and pendulum, and performance validation by full scale vehicle crash testing. The design process involved ...
Development of Simplified Truck Chassis Model for Crashworthiness Analysis
Yucheng Liu, M. L. Day - University of Louisville, USA
In this paper bending resistance of thin-walled channel beam is applied to create simplified model for truck chassis. In the simplified model, beam and nonlinear spring elements are used to model the side-rails, and equivalent beams are applied to represent the cross members. Both detailed and simplified models are used for crashworthiness analyses, and the results are recorded and compared. Relatively good agreement is achieved between ...
Development, Optimization, and Design for Robustness of a Novel FMVSS 201U Energy Absorber
David M. Fox - US Army Tank Automotive Research, Warren, MI
In order to streamline the product development process, the design space for FMVSS 201U impact performance of a steel mechanical energy absorber assembly was investigated by means of LS-DYNA 970 explicit finite element simulation methods in conjunction with statistical analytical procedures. A sequence of response surfaces, based on various levels of design parameters, was developed and used to determine minimal stopping distance for which ...
Drop Test Simulation of a Cooker Including Foam Packaging and Pre-stressed Plastic Foil Wrapping
Dan Neumayer - Bosch-Siemens-Hausgeräte
Madhukar Chatiri, Matthias Höermann - CADFEM GmbH
The present work deals with the numerical simulation of a drop test of a cooker including packaging foam and plastic foil wrapping. Additionally the pre-stressing of cooker and packaging due to thermal shrinkage of the plastic foil has been taken into account in the numerical investigation. For this, a thermal pre-stressing simulation of the plastic wrapping has been included before the actual drop test of the whole assembly has been ...
Evaluation of the Impact Condition for a High Capacity Spent Nuclear Fuel System
Mike Yaksh, S. Alan Lin - NAC International Inc.
Evaluations are performed for the structural component of a fuel basket in a sealed container which is used for maintaining the configuration of spent nuclear fuel during storage. Spent fuel assemblies are placed into a basket structure which is comprised of separate tubes whose positions are maintained by a series of pins and sockets and an exterior frame work of stiffeners. The canister is placed in a vertical storage cask. The controlling ...
Finite Element Modeling and Analysis of Crash Safe Composite Lighting Columns, Contact-Impact Problem
Alexey Borovkov, Oleg Klyavin, Alexander Michailov - St.Petersburg State Polytechnical University,
Martti Kemppinen, Mikko Kajatsalo - Mikkeli Polytechnic Research Centre YTI, Finland
Three Finnish associates, Tehomet Ltd, Fibrocom Ltd and Mikkeli Polytechnic Research Center YTI developed an internationally awarded energy absorbing lighting column product family in 2005. The design and dimensioning were assisted with static FEM computations, preliminary impact tests and full-scale impact tests made by YTI. The CompMechLab helped these associates in product optimization and further development by developing lighting column ...
Finite Element Modeling of Strip Curvature During Hot Rolling
Anup A. Kuldiwar
Finite element techniques have been used to decouple some of the major causes of strip curvature in the finishing stages of a hot strip mill. A plane strain elastic-plastic finite element model (HYPERMESH5.0) is used to predict the direction and severity of strip curvature caused by asymmetrical factors at each pass of the finishing mill. Predictions have been obtained using the elastic-plastic facilities of LS-DYNA Version 960. A full ...
Flexible Body Suspension System Modeling and Simulation Using MD Nastran SOL700 in VPG Environment
Casey Heydari, Ted Pawela - MSC.Software Corporation
Tim Palmer, Arthur Tang - Engineering Technology Associates, Inc.
Automobile durability and fatigue life prediction depend on road load generation approaches including proving ground testing, laboratory measurement and CAE simulations. Traditionally, the road load simulations are done with ADAMS using rigid body and modal flexible body approaches. With the newly available MD Nastran SOL700 capability, a new approach of using FEA-based flexible body modeling for suspension systems will be an attractive ...
Fluid Structure Interaction in LS-DYNA Using Lagrangian Interfaces, Automatic Re-meshing and Adaptivity
Facundo Del Pin, Grant O. Cook, Jr. - Livermore Software Technology Corporation
The present work discusses a new Fluid Mechanics approach that will be introduced in future versions of LS-DYNA to solve incompressible flows. The objective of this new formulation will be to solve fluid-structure interaction problems using Lagrangian interfaces. In this way large deformations of structures are treated in a more natural fashion making it simpler to define the physical domain. Furthermore the proposed approximation will also ...
Front Bumper Crashworthiness Optimization
Shokri El Houssini - Daan Engineering s.n.c
During a vehicles frontal crash, passengers jeopardize high acceleration and energy opposite to the mass follow direction of their bodies. This fact causes high injury to the passengers’ whole body; head, neck, chest, and legs. We started thinking of reducing this deceleration effect on passengers during the crash. This is because succeeding in reducing mass deceleration effect on the passengers’ bodies will lead to save passengers form ...
Honeycomb Sandwich Material Modeling for Dynamic Simulations of Aircraft Interior Components
S. Heimbs, P. Middendorf - EADS
M. Maier - Institute for Composite Materials (IVW)
An approach for modeling sandwich structures with a Nomex® honeycomb core and phenolic composite faces in the commercial finite element code LS-DYNA with solid elements for the core and shell elements for the thin faces is presented, which accounts for the major sandwich failure modes. Extensive material testing was conducted to determine the parameters for the composite face material model and for the orthotropic honeycomb material ...
Implementation of Constitutive Model for Thermoplastics with Some Preliminary Results
Torodd Berstad - SINTEF Materials and Chemistry
Odd Sture Hopperstad, Arild H. Clausen - Norwegian University of Science and Technology, Norway
Håvar Ilstad, Bjørn Melve - Statoil ASA
This paper presents an implementation of a material model for thermoplastics. Such materials have a quite complex behavior involving large elastic and plastic deformations, strong viscous and temperature effects, possible true stress softening and deformation-induced anisotropy. The demand of reliable constitutive models for thermoplastics is increasing, and a promising approach is due to Haward and Thackray (1968), who separated the response ...
Implementations of User Defined Shell Elements and Material Models to LS-DYNA and Their Application
J.W. Yoon, R.E. Dick - Alcoa Technical Center
Robustness, accuracy and good computational performance for large scale models are some of the salient requirements for general purpose finite element programs. A new one point quadrature shell element that meets these requirements has been previously developed in the works of Cardoso & Yoon (2005). In the theory, the finite element strain-displacement matrices are described in a convective coordinate system for the efficient implementation ...