3rd European LS-DYNA Conference

Paris, 2001

A review of the state-of-the-art in vehicle modeling for crashworthiness analysis using LSDYNA
Paul du Bois
A SEISMIC POST ELASTIC BEHAVIOR OF SPHERICAL TANKS
Pascal Pourcel - TECHNIP, Estelle Coussedière, Claire Gauthier, Nima Edjtemai - DYNALIS

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

A new Eulerian-Lagrangian coupling algorithm and improved multi-material ALE-capabilities have made LS- DYNA an efficient tool for analyzing large deformation processes, such as bird strike events and forging operations. This paper contains two example problems that illustrate the current features of the code.
AN EXPERIMENTAL AND NUMERICAL STUDY ON THE ENERGY ABSORBING CAPABILITY OF ALUMINUM EXTRUSIONS UNDER OBLIQUE LOADING
A. Reyes, M. Langseth, O. S. Hopperstad - Structural Impact Laboratory

Oblique loading was studied through static experiments and numerical simulations. The behavior of square aluminum columns in alloy AA6060 subjected to oblique loading was investigated experimentally for three different load angles. The square columns were clamped at one end and oblique load conditions were realized by applying a force with different angles to the centerline of the column. Numerical simulations were later carried out to validate the numerical model.
ASPECTS OF SEAT BELT MATERIAL SIMULATION
C. Pedrazzi, K. Elsäßer, S. Schaub - TRW Occupant Restraint Systems GmbH & Co. KG

The so-called D-ring dynamic overturning is an instability phenomenon occurring occasionally during car crashes. It can have a negative effect to the restraint function of the seat belt system and lead to increased seat belt forces to the occupant. In order to avoid this phenomenon the influence of different parameters has to be investigated. Therefore a simulation model has been created, using the Finite Element Code LS-DYNA 3D. Major questions to be clarified in this context are: • Define initial geometry for the belt running through the D-ring. • Choice of appropriate material model. • Influence of physical parameters, i.e. D-ring geometry, friction properties, belt material, belt forces, crash pulse, etc. The definition of the initial geometry and a feasibility study have been presented at the 2000 CAD-FEM conference [2]. The modelling method, results for a given baseline geometry, variations in different material models and the pre-simulation of a new concept of the D-ring, the so called “roller D-ring” are presented in the current paper.
CHARACTERIZATION AND COMPONENT LEVEL CORRELATION OF ENERGY ABSORBING (EA) POLYURETHANE FOAMS (PU) USING LS-DYNA MATERIAL MODELS
Babushankar Sambamoorthy - Lear Corporation

Polyurethane (PU) foams are one of the most widely used countermeasures for head impact protection. For accurate prediction of the head injury parameters, studies were conducted to establish a reliable LS-DYNA[1] material model to characterize PU foams. A 5.0pcf (80.09 g/l) PU foam was characterized using four different material models available in LS-DYNA for simulating foams, namely MAT_LOW_DENSITY_FOAM (MAT57), MAT_CRUSHABLE_FOAM (MAT63), MAT_BILKHU_DUBOIS_FOAM (MAT75) and MAT_FU_CHANG_FOAM (MAT83)[1]. The Finite Element Analysis (FEA) results were compared with the physical test results. The FEA material model resulting from the characterization procedure was validated using a component level, head impact correlation study. A simple side rail section was extruded about the SR1 target point and was impacted with a standard headform at an initial velocity of 15mph. Three different cases were investigated; baseline model with body-in-white (BIW) only, BIW with 18mm foam and BIW with 22mm foam. The Head Injury Criterion (HIC)[2] and acceleration curves from the simulation were compared with the physical tests.
CHARACTERIZATION AND COMPONENT LEVEL CORRELATION OF ENERGY ABSORBING (EA) POLYURETHANE FOAMS (PU) USING LS-DYNA MATERIAL MODELS
Babushankar Sambamoorthy, Tuhin Halder - Lear Corporation, Ford Division

Polyurethane (PU) foams are one of the most widely used countermeasures for head impact protection. For accurate prediction of the head injury parameters, studies were conducted to establish a reliable LS-DYNA[1] material model to characterize PU foams. A 5.0pcf (80.09 g/l) PU foam was characterized using four different material models available in LS-DYNA for simulating foams, namely MAT_LOW_DENSITY_FOAM (MAT57), MAT_CRUSHABLE_FOAM (MAT63), MAT_BILKHU_DUBOIS_FOAM (MAT75) and MAT_FU_CHANG_FOAM (MAT83)[1]. The Finite Element Analysis (FEA) results were compared with the physical test results. The FEA material model resulting from the characterization procedure was validated using a component level, head impact correlation study. A simple side rail section was extruded about the SR1 target point and was impacted with a standard headform at an initial velocity of 15mph. Three different cases were investigated; baseline model with body-in-white (BIW) only, BIW with 18mm foam and BIW with 22mm foam. The Head Injury Criterion (HIC)[2] and acceleration curves from the simulation were compared with the physical tests.
CRASH-SIMULATION OF HAT-SECTIONS RELIABILITY OF THE NUMERICAL MODEL
Paul Du Bois - consulting engineer, Thomas Frank - Daimler-Chrysler
CRASHWORTHINESS ANALYSIS OF A LOCK GATE IMPACTED BY THREE DIFFERENT RIVER SHIPS
Hervé Le Sourne, Stéphane Paboeuf, Guy Babaud - French Shipbuilding Research Institute, Jean-Claude Rodet - ECMT

This paper presents a study of the crashworthiness of the Pierre Bénite lock gate using a FEM approach. This gate situated in the Rhône river (south of Lyon) is collided by three different river ships : - a 6000 DWT convoy of barges with an initial velocity of 1m/s, - 3500 DWT carrier Rhône-Liner with an initial velocity of 1m/s, - a 2200 DWT passenger vessel with initial velocities of 1m/s and 2m/s. An analytical elastic analysis of the crashworthiness of a lock gate was carried out by J.C Rodet for the «Compagnie Nationale du Rhône». This analysis showed that : - the kinetic energy of a river ship which impacts a lock gate with a velocity of 1m/s is not entirely dissipated by the elastic energy of the lock gate, - the lock gate elastic response may result in dangerous reaction forces at the supporting chains, - empirical or analytical methods [2] generally used to determine the impact forces and resulting indentations of struck ship hulls may be applied to the lock gate but they have to be validated by a non-linear finite element analysis. An overview of the elastic analysis is presented in section 2 below. As we found that an elastic analysis was insufficient to quantify the damage, we decided to conduct a numerical analysis (section 3).
DEVELOPMENT AND VALIDATION OF A US SIDE IMPACT MOVEABLE DEFORMABLE BARRIER FE MODEL
Abdullatif K. Zaouk, Dhafer Marzougui - The George Washington University

Automotive safety regulations vary in different parts of the world. Dynamic side impact regulations, for example, are different than the ones in Europe. United States National Highway Traffic Safety Administration (NHTSA) and the European Union (EU) have each produced their own distinct testing procedures such as different deformable barriers, impact configurations and anthropomorphic test devices (dummies). Although both test procedures have the same final objective, estimate occupant responses in side impact, they differ greatly in execution. One of the main differences in testing is the Moving Deformable Barrier (MDB) used. The US MDB is designed to represent an average midsize vehicle in the US market, while the European MDB represents a mid size vehicle in Europe. The objective of this paper is to develop a finite element model representing the US deformable barrier for use in side impact simulations. Special emphasis is made on using the various available material models in LS-DYNA and the correct adhesive properties to predict the correct behavior of the honeycomb material. These models are validated to available full-scale tests. As known by many researchers, the main difficulty of MDB modeling is the prediction of the barrier complex failure modes. In side impact tests, the severe shear deformation of the honeycomb material, full densification of barrier edge, rupture of aluminum cover sheets, and tearing of honeycomb blocks are often observed. This complex pattern of honeycomb material failure mode makes it difficult to predict. Numerical instabilities, such as negative volume, sever hourglassing, and inaccurate predictions are often experienced.
Dynamics in Aerospace
Dr. Yves GOURINAT - ENSICA Professor Mechanics & Space Techniques

Airships Aircrafts Spacecrafts
EFFECTIVENESS OF COUNTERMEASURES IN RESPONSE TO FMVSS 201 UPPER INTERIOR HEAD IMPACT PROTECTION
Arun Chickmenahalli - Lear Corporation Michigan, USA

Analysis and development of countermeasures in meeting vehicle upper interior free motion headform (FMH) impact safety requirement (FMVSS 201) has become an important aspect for engineers. FMVSS 201 safety regulation stipulates that the Head Injury Criterion, HIC (d) should be less than 1000 when a FMH is impacted at a speed of 15 mph. The interior components of a vehicle generally do not generate high HIC (d) numbers by themselves but the steel structures behind them to which they are attached do so. The gap between the interior component and the steel structure makes a provision for the introduction of some countermeasures which can absorb the kinetic energy of the FMH in the form of internal energy so that the acceleration response of the FMH does not generate high HIC (d) and Peak G force. This paper discusses a methodology in developing a countermeasure for automotive interior components to comply with FMVSS 201 requirements. The effectiveness of introducing a countermeasure between the headliner and the steel structure or the body in white (BIW) is evaluated through Finite Element Analysis using a dynamic finite element tool, LS-DYNA. Several geometric configurations of the countermeasure have been studied to ascertain its suitability in absorbing the kinetic energy of the FMH. Parametric studies have been carried out by varying the thickness of the countermeasure to see the effect on the injury parameters, HIC (d) and Peak G. Finite element analysis results are compared with the test results as per the FMVSS 201 regulations to deduce concrete conclusions about the effectiveness of the countermeasure.
EFFICIENT MODELING OF PANEL-LIKE TARGETS IN PERFORATION SIMULATION
Guangyu Shi, Junyan Guo and Chun Lu - Institute of High Performance Computing Singapore

This paper studies the application of thin shell elements and solid shell elements in the structural modeling of panel-like targets in finite element perforation simulations. LS-DYNA is used for the present numerical investigation. By comparing the projectile residual velocities and impact pressures given by the shell element targets to those obtained form the solid element target, this work shows that the solid shell element modeling of panel-like targets can not only save a lot of computational effort, but also be able to give good results if the target panels satisfy certain conditions. Therefore, the shell element modeling of targets is an efficient model in the performance simulation of projectiles penetrating through panel-like targets. A preliminary criterion for the validity of the shell element target model is also proposed in the paper.
ESTIMATION OF THE TRANSVERSE CRUSH RESISTANCE OF A SECTION OF THE T23 FRIGATE
Dr. G.S. Kalsi - Cranfield University, UK

Ocean-going vessels are very complex structures, and can have displacements ranging from hundreds to tens of thousands of tons. In the case of bulk carriers and tankers, this can be as much as half-a-million tons. When in motion, they can possess very large amounts of kinetic energy even if their velocities are small. They therefore have the potential to cause serious damage in case they are involved in a collision. Ships moving in ports or harbours often move in limited space and there is always the possibility that an accidental collision may occur, albeit at a low velocity. If either the striking or struck ship carries sensitive or hazardous materials then the consequences of a collision may be far more serious than that consisting simply of structural damage to either ship. One way of reducing potential damage to ships carrying such cargo is to restrict the travel velocities of approaching ships to some limiting values. The reliable estimation of such velocities needs as a minimum a knowledge of the crush characteristics of at least the target vessel, and preferably that of the striking vessel too. The situation addressed in this paper is one where a moored vessel, a T23 frigate, is struck normally by a similar moving vessel. It is required to estimate the crush characteristics of the struck vessel around the chosen impact location. A knowledge of the crush characteristics can then be used to derive limiting approach velocities in order to minimise damage, intrusion, etc. in the struck vessel. A three-dimensional mesh of the struck section of the moored ship has been modelled using finite elements. The implicit algorithms in LS-DYNA3D(1) were used to simulate the crushing of this ship section. The paper presents the method of analysis and the derived crush characteristic, which is then used to estimate limiting velocities for an approaching vessel
F - Ma = 0 The unique certitude in Aerospace ?
Dr. Yves GOURINAT - ENSICA Professor Mechanics & Space Techniques
FEM-PROCESS-SIMULATION OF HYDROMECHANICAL DEEP-DRAWING
Matthias Aust - University of Stuttgart (Germany)

The FEM-Process-Simulation of metal forming processes has been proven to be useful during the design stage of components and toolings. However, this is not valid for relatively new processes, e. g.. hydromechanical deep-drawing. Hydromechanical deep-drawing is related to conventional deep-drawing, but the process is quite different. When using hydromechanical deep-drawing, instead of a rigid female die a counter pressure pot is used to form the sheet metal against the punch. The process modeling and application of conventional deep-drawing is a well-known process with a great amount of practical and theoretical experience. Therefore a large database of knowledge exists. In contrast to conventional deep- drawing, for hydromechanical deep-drawing the practical and theoretical knowledge is limited. Since the application of hydromechanical deep-drawing is becoming more interesting (e.g. for the production of niche cars), the demand of theoretical and practical knowledge is increasing
FINITE ELEMENT ANALYSIS OF DUCTILE FAILURE IN STRUCTURAL STEEL SUBJECTED TO MULTIAXIAL STRESS STATES AND HIGH STRAIN RATES
T. Børvik, O.S. Hopperstad, S. Dey, M. Langseth - Norwegian University of Science and Technology, T. Berstad - LSTC

Notched specimens of the structural steel Weldox 460 E have been tested at high strain rates in a Split Hopkinson Tension Bar. The aim was to study the combined effects of strain rate and stress triaxiality on the strength and ductility of the material. It is further considered important to obtain experimental data that may be used in validation of constitutive relations and fracture criteria. The force and elongation of the specimens were measured continuously by strain gauges on the half-bars, while the true fracture strain was calculated based on measurements of the fracture area. Optical recordings of the notch deformation were obtained using a digital high-speed camera system. Using image processing of the digital images, it was possible to estimate the true strain versus time at the minimum cross-section in the specimen. The ductility of the material was found to depend considerably on the stress triaxiality. Non-linear finite element analyses of the notched tensile specimens at high strain rates have been carried out using LS-DYNA. A computational material model including viscoplasticity and ductile damage has been implemented in LS-DYNA and determined for Weldox 460 E steel. The aim of the numerical simulations was to assess the validity of the material model by comparison with the available experimental results.
HYDROPLANING SIMULATION USING FLUID-STRUCTURE INTERACTION IN LS-DYNA
Masataka Koishi, Toshihiko Okano - The Yokohama Rubber Co.,Ltd., Lars Olovsson - LSTC, Hideo Saito, Mitsuhiro Makino - Fujitsu Ltd.

The hydroplaning phenomenon is a key issue for safe driving on a wet road. However, it has been extremely difficult to predict the onset of hydroplaning using numerical simulation. The hydroplaning is a complex multi-physics problem, involving rolling tires with complex groove geometry and surrounding water. Recently the fluid-structure interaction capability has been developed for both Eulerian and ALE formulations in LS-DYNA. Using this capability, transient hydroplaning can be modeled for both the reference frame fixed on a moving car (Eulerian fluid) and the reference frame fixed on the ground (ALE fluid). In the present work, both tire and fluid are modeled with Finite Elements. Numerical examples of the passenger car radial tire sized 195/65R15 with V-shaped grooves are illustrated. In the proposed simulation, we obtain a tire completely lifted by the water layer. In addition, the difference in lifting velocities between normal rotational direction and reverse rotational direction has been evaluated. The numerical results correspond well to the experimental observations at a proving ground.
IMPROVED SPOTWELD SIMULATION WITH LS-DYNA - NUMERICAL SIMULATION AND COMPARISON TO EXPERIMENTS
Karl Schweizerhof, Werner Schmid - CAD-FEM GmbH, Herbert Klamser - PORSCHE AG

Functioning of the body of a car structure with respect to stiffness, durability and crashworthiness is mainly dependent on the connection between the manufactured parts, in particular, if mainly shell type structural parts are used. Spot welding is the dominant technique used nowadays to connect shell type parts. Though spot welding is a fully automated process and a well known technique since many years, there is little knowledge about the behavior of the spotweld connections under single strong impulse loading. This knowledge, however, is one major ingredient for a proper repre-sentation in FE crashworthiness models. In order to capture the correct mechanical behavior of a spotweld connection with its complex stress state, in prin-ciple a fully 3D continuum mechanical model is needed, e.g. as the welding process itself has a major influence on the material properties in the vicinity of the spotweld due to the high temperatures involved locally. In addition from experiments it is known that the failure process of a spotweld connection is strongly dependent on the form of the spotweld and local rupture takes place. In FE crashworthiness models, however, such detailed models cannot be incorpora-ted for the many thousands of spotweld connections due to efficiency reasons. Thus alternative models have to be developed to include the major effects of the spotweld behavior within full car crash models with only little influence on the efficiency of the FE analysis. Taking the experiences gained from many years of modeling in the automotive in-dustry a number of different FE spotweld models are discussed and the results of the analyses with LS-DYNA are compared to some experimental results from the investi-gations initiated by the FAT- working group 27 (Forschungsvereinigung Automo-biltechnik e.V. AK 27). Within the analysis particular focus is on the sensitivity of the results concerning the various spotweld models tested on single spotwelds. Finally the influence of the vari-ous models on the results for a realistic part under crashworthiness loading is shown.
IMPROVING THE IMPACT RESISTANCE OF MASONRY PARAPETS
G. Beattie, T.C.K. Molyneaux - University of Liverpool, M.Gilbert, B.Hobbs, S.Burnett, P. Newton - University of Sheffield, D.A.Gration - Arup Advanced Technology Group

There are over 60000 masonry bridge parapets in the UK. Whereas steel and concrete parapets are well covered by design standards masonry parapets are not. Initially LS-DYNA was used to model vehicle impacts on various forms of masonry parapet. The results were encouraging, with good qualitative agreement between tests and analysis. The same finite element modelling strategy was subsequently used to help develop a guide for assessment (County Surveyors’ Society Guidance Note, 1995) and a new British Standard (BS 6779 pt 4, 1999). The findings of the initial study demonstrated that unreinforced masonry could perform reasonably well in preventing vehicle penetration and controlling the rebound of impacting vehicles. However the work highlighted two areas that required additional study: (i) in critical situations requiring improved impact resistance, advice on alternative strengthening methods or new build options was needed; (ii) the discrete analysis approach adopted, using LS-DYNA tied interface type 9, required use of unrealistic failure parameters in order to prevent a premature (brittle) failure. The current project is addressing these two issues by the use of both physical tests and finite element analysis. The test work involves a range of small and medium scale tests that provide data for the numerical work. These tests address the issue of dynamic enhancement of the shear and tensile strength of masonry. In addition, the effects of fracture energy and dilatancy under high strain rates are being considered. Test methods have also been developed to evaluate the interaction between the masonry and reinforcement under varying strain rates. Full-scale tests are also being used to both provide analytical data in the early stages of the project and to validate the use of LS-DYNA as a predictive tool in the latter stages of the project. The fullscale test walls range from approximately 9m to 20m in length. In the numerical models the existing LS-DYNA interfaces are being modified to incorporate the effects of fracture energy and dilatancy. Early results are promising, allowing realistic material properties to be used and seeming to explain the apparent high strain rate sensitivity of the measured data. Strategies for modelling reinforcement in a masonry wall are also being developed. Related work where LS-DYNA is being used to model masonry arch bridges is also summarised within this paper.
IN BORE BEHAVIOUR OF LARGE CALIBRE ARMOUR PIERCING FIN STABILISED DISCARDING SABOT PROJECTILES.
N.Eches, N.Paugain, C. Doffémont - Giat Industries

The efficiency of large calibre armour piercing fin stabilised discarding sabot projectiles (APFDS) is primarily linked to their terminal ballistics performances. But other parameters, such as its accuracy and its yaw at the impact have also a large influence on the performance. These two parameters magnitude, as well as the survivability of the projectile during the launch phase are greatly affected by the interaction between the projectile and the gun, also known as the “balloting”. Nowadays, the accurate description of the rod free flight has been made possible thanks to Computational Fluid Dynamics calculations, allowing to predict the flight quality or the retardation, and back calculation of initial disturbances of an unexpectedly odd shot. But this situation is not true for the early moments of the firing sequence, i.e. the projectile inbore travel and the sabot separation. For the latter, a long way to go remains. But, in the field of projectiles in-bore behaviour, a lot of works have been performed, using different numerical methods, which allowed scientists to make significant progress. This paper describes some of the works performed in the Giat Industries Weapon and Ammunition Systems Division (DSAM), whose purpose was to understand how the interactions between the weapon and the projectile could affect its mechanical behaviour and its muzzle exit conditions.
INFLUENCE OF MANUFACTURING PROCESSES ON THE PERFORMANCE OF VEHICLES IN FRONTAL CRASH
Dr.-Ing. Horst Lanzerath, Dr.-Ing. Omar Ghouati, Dr.-Ing. Jürgen Wesemann - Ford Forschungszentrum, Dr.-Ing. Robert Schilling - Ford-Werke AG

The importance of new material applications for improved passive vehicle safety is increasing. Automotive companies are using CAE methods to predict the crash behaviour of cars and to select materials for body structures, which fulfill the safety targets. The quality of crash simulations heavily depends on the material models used for these investigations. In this paper results of research projects on the application of new high strength steel sheet metal in side rail structures are presented. The simulation models used in these studies are described and their importance for Finite Element applications in passive safety is underlined.
INPUT PARAMETERS FOR SPRINGBACK SIMULATION USING LS-DYNA
Bradley N. Maker, Xinhai Zhu - Livermore Software Technology Corporation

LS-DYNA has been applied to springback simulation by a large number of users, with generally mixed results. Some results have demonstrated 70% accuracy or better, while others have been entirely misleading. In order to eliminate inconsistent results, this report presents a standard procedure for conducting springback simulations with LS-DYNA. The “seamless” and “dynain” methods for springback are described, followed by a description of general implicit springback problem set-up. Recommendations are given for anticipating and improving springback prediction accuracy. Wherever possible, LS-DYNA keyword input data is shown to clarify the presentation. Recommended input parameters are identified in boldface type and included in boxed keyword input syntax for quick reference. A boldface zero value is entered for required input data which is model specific, such as the termination time term.
INTEGRATED ANALYSIS OF FORMING AND CRASHWORTHINESS OF HIGH STRENGTH ALUMINIUM BUMPERS USING LS-DYNA
O.P. SØVIK, A. ARTELIUS, T.J. BROBAK - Hydro Automotive Structures

The front and rear bumper beams are important parts of the overall safety system of modern cars. Due to aluminium's high strength to weight ratio, bumper beams made of extruded aluminium profiles have become an attractive contribution to the car manufacturers’ constant strive for reducing the weight of their cars. In order to meet the various demands with respect to weight, strength, functionality, packaging , etc., a significant degree of complex forming after extrusion is normally required. As a leading supplier of high strength aluminium bumpers, Hydro Automotive Structures have for several year been using advanced FE tools in their product and process development. However, due to the close link between crash performance and geometrical shape of the bumper, the need for a tighter integration between process and product simulations has been realised. The present paper shows examples of how such integrated analyses are carried out in an industrial context as well as some results indicating the clear benefits of such an approach.
LS-DYNA PERFORMANCE ON ULTRASPARCTM -III SERVERS AND WORKSTATIONS
Youn-Seo Roh, Henry H. Fong - Sun Microsystems

Sun Microsystems recently announced a new line of high-performance Sun FireTM Midframe servers and Sun BladeTM 1000 workstations based on 750-MHz UltraSPARC-III microprocessors. These new computers offer exceptional performance for numerically intensive MCAE applications at reasonable prices. This paper presents single- and multi-processor performance and scalability results of LS-DYNA running on these systems. Results of both OpenMP and MPI binaries are compared to those of existing server platforms. Scalability and performance results are presented for the OpenMP binary that has been built with Sun's native OpenMP compiler extension. Comparisons with a previous version using libraries from KAI show significant improvements both in the absolute execution time and the scalability. The MPI executable tuned for the new Sun Fire server resulted in a 40-60% improvement in execution time over the entire range of processor counts.
Modelling of an automobile tyre using LS-DYNA3D
W. Hall, R. P. Jones, J. T. Mottram - University of Warwick

This paper describes a finite element model used to investigate the quasi-static behaviour of a stationary automobile tyre vertically loaded against a stiff horizontal surface. The model includes a representation of the tyre, a steel wheel and surface. The tyre is represented in detail by a number of tyre components, the wheel and surface are coarsely modelled. LS-DYNA3D is used to simulate the inflation of the tyre, the fit between the tyre and the wheel and the vertical loading of the tyre against the surface. Simulation results, such as the load-deflection characteristics and the load-tyre/ground contact patch dimensions are compared with mixed success to those obtained experimentally. The stiffness of the tyre components and the inflation pressure are varied independently and the simulation is repeated. The resulting load-tyre/ground contact patch dimensions are discussed in context with the development of a rolling tyre model.
MODELLING THE SHAKEN BABY SYNDROME
I.C. Howard, E.A. Patterson, J. Langley - University of Sheffield (SIRIUS)

Physical child abuse is common. For the UK alone, an informed estimate is that every year more than 200 infants die from brain injuries inflicted by violent shaking (“Shaken Baby Syndrome”). Around twice this number, who actually survive such treatment, are left with severe mental and physical disability including blindness due to associated damage to the retina (the light-sensitive part of the eye). Although it is now distressingly obvious that shaking often causes debilitating brain and eye injuries, it is unclear how it happens, whilst such combined injuries are rare even in severe accidental head trauma with skull fractures. The work involves the use of LS-DYNA to explore some of the mechanical fundamentals of these phenomena. Specifically, it addresses the difference between motions induced in the brain through the “single event” loading that is normally associated with impacts and those induced by shaking. The paper also describes a set of experiments that measured the accelerations induced by shaking an automotive dummy of a 9-month old child. The “shakers” included young men and women, and middle-aged men and women. They also ranged between small and delicate, and large and muscular. The data from this sort of experiment is essential input to the DYNA simulations.
NUMERICAL AND EXPERIMENTAL STUDY OF SAFETY NET SYSTEMS FOR HUMAN AND EQUIPMENT SECURITY (SKI APPLICATION)
BEN YAHIA Fayçal - DYNALIS, GOURINAT Yves - ENSICA

Human and material safety systems evolve continuously to become more perfect and face increasing requirements. Indeed, important changes of usage conditions and precautions have been caused by the technological progress of the various domains of life (means of transportation, sporting equipments etc.). In order to follow this technological expansion and optimize it for the benefit of the human beings, several research projects were carried out. In this framework, the following study is presented, concerning the safety systems by keeping- back nets.
NUMERICAL SIMULATION OF THE WOOD RESPONSE TO THE HIGH VELOCITY LOADING .
J. Buchar - Mendel University of Agriculture and Forestry, Czech Republic, J. Voldrich - Research Center of the West Bohemia University, Czech Republic

The experiments where the freely supported spruce beams have been loaded by the detonation of an explosive charge have been evaluated using of the numerical simulation. The explicit Lagrangean finite element code LS DYNA 3D has been used to analyse the beam response. The wood has been considered as global orthotropic linear elastic material with a material damage. The material damage has been described by the strain at the wood failure. This simple material model seems be better than the Tsai - Wu model widely used in another numerical simulations. Spruce wood , beam , material damage, explosive loading, finite element , numerical analysis Wood is an anisotropic cellular material such as honeycombs, metal ring systems, polymeric foams and some others . These materials are very convenient for the design of impact energy absorbers and as core materials in lightweight structures. Their behaviour under static loading is well summarised in the book (Gibson and Ashby 1988). Wood in particular has also been used as a protective material for high velocity impact events for many centuries (Johnson 1986a, 1986 b) and is very often used as an impact energy absorbing material at the design of the transportation flasks for nuclear fuel etc. There have been only a few systematic studies of the behaviour of wood under high rates of loading following from some impact events (Johnson 1986a). Recently the extensive impact test data have been obtained for some wood species (Reid and Peng 1997, Harrigan et al. 1998) . These data have been used for the development of the models of the macro – deformation and micro – deformation modes resulting from the dynamic uniaxial compression at the specimen impact. The present paper focuses on the other kind of the dynamic loading which is the effect of the detonating explosive. The study of this problem has some practical applications . Wood may be successfully used as a part of a structure which should absorbed most of the energy of the mine explosion etc. It is obvious that there is a variety of different arrangements, kind of wood, thickness of wood layer etc. In order to reduce the number of expensive experiments some reliable numerical simulation is necessary. The present paper deals with the problem of such numerical analysis using of the finite element code LS DYNA 3D.
NUMERICAL SIMULATIONS OF DUCTILE FAILURE IN EXTRUDED ALUMINIUM ALLOYS USING A COUPLED MODEL OF ELASTO-PLASTICITY AND DAMAGE
O.-G. Lademo, O.S. Hopperstad, T. Berstad, M. Langseth - Structural Impact Laborator

A test programme has been carried out to establish the mechanical properties of three extruded aluminium alloys. The investigated alloys exhibited significant anisotropy in strength, plastic flow and ductility. The anisotropy is mainly due to crystallographic texture, and an anisotropic yield criterion is needed to describe the mechanical behaviour. Several yield criteria were evaluated against the experimental data. The yield criterion Yld96 proposed by Barlat and co-workers was found to be superior with respect to accuracy for the actual aluminium alloys. In an attempt to model ductile failure of the investigated materials, a coupled model of elasto-plasticity and ductile damage was implemented in LS-DYNA for plane stress analysis with corotational shell elements. The material model combines the anisotropic yield criterion Yld96 with the associated flow rule, isotropic strain hardening and isotropic damage. The parameters defining the yield criterion and the strain hardening were determined from tensile tests and pure bending tests, while the damage parameters were identified using inverse modelling of tensile tests performed with purpose-made specimens. A series of biaxial tensile tests was also completed, and the results from these tests were used in an attempt to evaluate the constitutive model.
ON TECHNIQUES FOR SIMULATING EFFECTS OF CAVITATION ASSOCIATED WITH THE INTERACTION BETWEEN STRUCTURES AND UNDERWATER EXPLOSIONS USING LS-DYNA
Q.W. Ma, D.J. Andrews - University College London

In this paper, a two-step technique is suggested to reduce the reflection of shock waves from a truncated boundary without significantly smearing the incident shock wave and to suppress spurious oscillations without significantly affecting accuracy. By comparing the results for a one-dimensional case with a wellknown analytical solution, it is shown that the technique works very well.
OPTIMISATION AND ROBUSTNESS OF SIDE AIRBAG DESIGN AND ANALYSIS
Tayeb Zeguer - Jaguar cars

In order to yield significant added value, computer model need to reach to a level of reliability that enables decisions, which are only based on simulation results. Airbag deployment is highly non linear and non reproducible. Scatter in all system properties and boundary conditions also cause scatter in the performance of the system. The aim of this paper is to use stochastic simulation approach to include this natural scatter into the computer models. This allows evaluation of the performance scatter and thus an assessment of reliability and quality of the simulated system. Stochastic simulation can be used for system improvement, which offers a further application tool for system optimisation. The problem is not to find optimum solution in a mathematical sense, but to develop sufficiently good and especially robust solutions for real world situations. In this paper stochastic approach will be introduced and applied to the side airbag deployment.
OPTIMIZATION OF STIFFENED LAMINATED COMPOSITE CYLINDRICAL PANELS IN THE BUCKLING AND POSTBUCKLING ANALYSIS.
A. Korjakin, A.Ivahskov, A. Kovalev

Stiffened plates and curved panels are widely used as primary structural elements in aerospace, marine and civil engineering. Their stable postbuckling behavior and their capability to sustain loads far in excess of their initial buckling loads may lead to considerable weight savings, if their postbuckling strength is fully utilized and possible fatigue problems are eliminated. In the presence of large deflections, bifurcations, load and displacement limit points, the analysis of arbitrary anisotropic shells requires the adoption of incremental and iterative procedures capable of tracing the complete load- displacement path. Although the true response is dynamic in nature, a fully static solution is followed in most cases. Stiffened panels loaded in axial compression were extensively studied and employed in aeronautical structures in the thirties, forties and beyond, yielding the effective width. In the last decades, the trend to optimize the design shear panels, and the employment of composites and higher strength metals, has led to similar required relative stiffnesses in both civil and aeronautical engineering. The civil engineers employ stiffer flanges in order to improve the postbuckling strength of the web and the aeronautical engineers decrease the relative flange cross-sectional area in order to save weight. The nonlinear analysis of shells requires the efficient blend of finite element technology and path-following techniques. Due to the increased computational effort of the incremental and iterative solution process, it is imperative to obtain the structural response by simple, inexpensive and accurate finite elements. In this paper the postbuckling performance of composite shells using computer code LS-DYNA is analysed.
PARALLEL ENGINEERING SIMULATIONS BASED ON FORMING SIMULATION OF A HEAT EXCHANGER PLATE
Gabrielson P. - Alfa Laval Lund AB, Thuvesen D. - The Swedish Institute of Production Engineering Research

Normally, simulation regarding computational fluid dynamics (CDF), structural mechanics and heat transfer simulations in sheet metal applications are made without a forming simulated part. Instead the simulation is based on especially constructed parts, with some kind of nominal geometry, only for the specific simulation. This paper presents the use of sheet metal forming simulation of an advanced thin sheet metal part as input to other simulations. Here forming simulation provides input data for different parallel simulations: simulation of computational fluid dynamics (CFD), simulation of structural mechanics and thermal heat transfer simulations. From the forming simulation output e.g. pressed part geometry, it should be possible to use sheet metal thinning, residual stress and strain as input in other simulations later on. However, today it is not trivial to export and use the result from LS-DYNA to the desired application. We have developed a method for carrying a correct geometry into parallel simulations with input from forming simulated section. A special heat exchanger plate, with intensive and sharp patterns, was developed to study the influence of variations in geometry of the pressing tool. The sheet metal forming simulation was performed with LS-DYNA. A C++ program was developed to calculate new nodes in the surface of forming simulated section. This to be able to created a geometrically correct solid model as input in parallel simulations. A simulation of computational fluid dynamics was performed with forming simulated section of a heat exchanger plate as input to verify method. Result achieved from forming simulation regarding thickness variation and material inflow were compared with real pressing results for stainless steel material. The comparison showed good agreement between the simulations and the measured parameters on a processed heat exchange plate. Previously the design engineer could actually make real test tools and press metal sheets in the workshop. This is very expensive and even more important; it takes a lot of time. Here the forming simulation is a very powerful tool. Geometrically correct model achieved with described method and forming simulation is possible to use as input in simulation of computational fluid dynamics (CFD). In a similar manner the simulation of structural mechanics and thermal heat transfer are possible to perform with thickness variations instead of nominal geometry. The sheet metal simulation is nowadays used for a number of different purposes. The main purpose is to detect problems with the tools. The second aspect is to be able to make other useful simulations with the geometry of the simulated heat exchanger plate and it is necessary to be well established in this IT-area to be a competitive manufacturer of heat exchanger plates in future.
PARALLEL PERFORMANCE OF LS-DYNA ON THE NEXT GENERATION OF COMPUTER SYSTEMS
Jeff Zais - IBM

LS-DYNA is available on a wide variety of computer platforms, ranging from commonplace personal computers to sophisticated vector processors to high-performance scalable servers. This presentation will review historical LS-DYNA performance and look forward to what can be expected in the next generation of computer platforms. The capability of available computer platforms always has a bearing on what type of simulations LS-DYNA end users can run. In the past, departmental machines such as DEC VAX servers provided many computing cycles to users. Porting of the code to Cray vector machines made overnight full-car crash simulations practical. Models grew larger but could still be run overnight as machine speeds increased and SMP parallel versions became available. At the same time, UNIX workstations increased in capability to the point where many sophisticated simulations could be run on desktop machines. Most recently, significant advances in LS-DYNA and computer hardware have taken place in two different areas: scalable servers, and machines based on low-cost processors. The advances are being driven by the growing acceptance of the MPI version of LS-DYNA, the level of performance available from low-cost commodity processors, and the level of performance available from high-performance processors available in scalable systems. Current performance examples and trends in microprocessor improvement can be used to give users guidance on what levels of LS-DYNA performance will be attainable in the next few years.
QUASI-STATIC LIMIT LOAD ANALYSIS BY LS-DYNA IN COMBINATION WITH ANSYS
Wilhelm Rust, Ulrich Franz - CAD-FEM GmbH

It is shown when and how quasi-static limit load analyses can be performed by a tran-sient analysis using LS- DYNA. Then we focus on the remaining benefits of implicit analysis and how a proper combination of ANSYS and LS-DYNA can be used to prepare the transient analysis by common preprocessing and static analysis steps. Aspects of discretization, solution control, consideration of imperfections and methods of checking the results are outlined.
S.P.H. : A SOLUTION TO AVOID USING EROSION CRITERION?
Céline GALLET - ENSICA, Jean Luc LACOME - DYNALIS

A new particle element has been added to LS-DYNA. It is based on Smoothed Particle Hydrodynamics theory. SPH is a meshless lagrangian numerical technique used to modelize the fluid equations of motion. SPH has proved to be useful in certain class of problems where large mesh distortions occur such as high velocity impact, crash simulations or compressible fluid dynamics. First, the basis principles of the SPH method will be introduced. Then, the model of perforation of a bullet through a thin plate will be presented. Two models are realised: one is made of lagrangian brick elements only, and the second one uses SPH elements for the plate. Finally, a discussion is proposed on the different methods used to deal with the penetration problem.
SHAPE OPTIMIZATION FOR HEAD AND KNEE IMPACT FEATURING ADAPTIVE MESH TOPOLOGY AND A DISCRETE VARIABLE
Nielen Stander, Mike Burger, Suri Balasubramanyam - Livermore Software Technology Corporation, Sharath Varadappa - Quantum Consultants, Inc., Detroit

A successive linear response surface method (SRSM) is applied to the shape optimization of vehicle crashworthiness problems involving knee and head impact. A preprocessor is used to parameterize the geometric model and mesh topology. An upper limit on the element size is used as a criterion for the mesh adaptivity. Simulation is conducted using the explicit dynamic analysis method. The study demonstrates the effectiveness of adaptive meshing and simulation-based shape optimization in problems of complex behavior such as crash simulation.
SIMULATION OF A DETONATION CHAMBER TEST CASE
Daniel Hilding - Engineering Research Nordic AB

The purpose of a detonation chamber is to ensure vapor and fragment containment during the destruction of explosive munitions. The toxic vapors generated by the detonation can be vented into a filtration unit. Compared to free air detonations, the use of a detonation chamber reduces the environmental impact of munitions destruction. The manufacture and testing of a detonation chambers is time consuming and expensive. At present, new designs are mainly based on experience with previous designs and rough estimates. A more accurate and reliable method for predicting a chambers performance would therefore be a significant aid in the design process. This paper considers the most straightforward method for predicting the performance of a chamber design, which is to simulate a munitions detonation in the chamber. The simulation is accomplished using LS- DYNA's multi-material Eulerian methods.
SIMULATION OF NONLINEAR VISCO-ELASTICITY
Kazuyoshi Miyamoto, Hiroshi Yoshinaga, Masaki Shiraishi, Masahiko Ueda - Sumitomo Rubber Industries,LTD.

CAE has been applied for the development of various industrial products in many kinds of fields. They are not only products made of metals but also products made of polymeric materials, such as tires, balls for various kinds of sports, press ink rolls, and so on. These materials, such as rubber and synthetic resin have viso-elastic properties. And most of them have nonlinear characteristics. In case of dealing with them, it is very important for accurate simulation to apply nonlinear visco-elasitc material models. Especially it is necessary in the field of Impact. Because impact is in the condition of large strain, or high-speed strain rate, performances as products depend on nonlinearity. Therefore it is not reasonable for the simulation of impact to input material properties measured by visco- elastic spectrometer well known as a typical visco-elastic measurement. They are in the condition of small strain on the order of few percent and low strain rate on the order of a few [/s]. It is necessary to measure them in large strain on the order of more than ten percent and high strain rate on the order of thousands [/s] same as practical condition. However there had not been any testers to measure viso-elastic material properties in the condition of large displacements and high deformation rates before. Recently, the split Hopkinson pressure bar, which is originally for evaluation of metals, has been improved for evaluation of polymeric materials. And material properties of some polymeric materials in that condition have been evaluated. In this study, a nonlinear visco-elastic material model is developed by using the measurement results from the improved split Hopkinson pressure bar. Further, the tests of the split Hopkinson pressure bar are simulated, and good correlation with the experiment is obtained. Finally the restitution tests of golf ball is simulated as an example of application. Agreement between the experiment and the simulation is confirmed.
SIMULATIONS OF HYPERVELOCITY IMPACTS WITH SMOOTHED PARTICLE HYDRODYNAMICS
Dominique Lacerda, Jean-Luc Lacome - DYNALIS, France

This paper is devoted to the results of Smoothed Particle Hydrodynamics (SPH) simulations of high velocity impacts on thin aluminium plates using LS-DYNA computer code. The numerical results of the damage produced on plates are compared with experimental data. Two simulations are presented : - An aluminium sphere impacting an aluminium plate at 6.64 km/s - A steel sphere impacting an aluminium plate at 5.53 km/s Experimental and numerical results are in good agreement.
SOME EXAMPLES OF ENERGETIC MATERIAL MODELLING WITH LSDYNA
Michel QUIDOT -SNPE Propulsion – Centre de Recherches du Bouchet

SNPE is using DYNA codes for more 15 years for characterisation and modelling of energetic materials : high explosives, solid propellants, gun propellants and pyrotechnic systems for functioning, safety, survivability and vulnerability analysis in space and defence applications. This paper presents some examples of the use of LSDYNA in the field of solid mechanics, fluid mechanics and detonics. The first example concerns the development of a constitutive model for a cast PBX. A general dynamic viscoelastic model developed in LSDYNA is used to analyse Split Hopkinson Pressure Bar (adapted for soft materials characterisation) experiments, reverse Taylor test instrumented by high speed framing camera and VISAR system. A postprocessing variable implemented is used for analysing dynamic failure in dynamic Brazilian tests performed with SHPB system. Two others short examples are given : functioning of a pyrotechnic system separation in space application and LSDYNA/Euler simulation of the interaction of blast waves with explosive charges in sympathetic detonation phenomena.
STATE-OF-THE-ART IN THE USE OF (LS-DYNA) FORMING SIMULATION IN HYDROFORMING AND PRECEDING PROCESSES
A. Haas, H. Bauer, I. Lerch -FH Aalen, M. Mihsein, R. Hall - University of Wolverhampton, A. Böhm - Siempelkamp Pressen Systeme GmbH & Co.

Rapid and reliable methods for component development and economic manufacturing layout are today crucial factors for the application of hydroforming techniques in mass production of lightweight components for the automotive industry. Optimum design of components taking into consideration special process-specific factors enhances safety and also the cost-effectiveness. The feasibility study, the component configuration and definition of a production sequence are closely interlinked. Once the approximate product geometry or component design, respectively, is known, a FEA (Finite Element Analysis) simulation has to be performed to study the forming process and appropriate die design. The FEA has become an established feature of hydroforming technology. The objective of FEA study is to replace costly and elaborate experimental testing by fast, low-cost computer simulation.
THE CASE FOR EXPLICIT FINITE ELEMENT ANALYSIS OF FABRIC SYSTEMS, A PRESENTATION OF REAL WORLD APPLICATIONS AND RESULTS
A.P. Taylor - Irvin Aerospace Inc

This paper presents the application of Finite Element Analysis (FEA) to real world problems typically encountered in the Aerodynamic Decelerator Systems field, and to fabric engineering in general. All simulation results are presented from the commercially available Explicit FEA package LS-DYNA, as this has been our most successful application. Our experience with the application of Implicit FEA, is that commercially available codes cannot handle the large deflections associated with fabric systems. The presentation of test to simulation comparisons, now available from several projects, is also presented herein. These provide the reader with a feel for the level of precision/validation possible with today’s simulation tools. Finally, we close with a discussion of where Irvin, and eventually our industry, will apply computational techniques in the coming years.
THE GENERATION OF A MATERIAL MODEL TO REPRESENT THE MECHANICAL BEHAVIOUR OF AN ALIPHATIC POLYETONE (CARILON EP) AT HIGH STRAIN RATE EVENTS AND LOW TEMPERATURES.
Jerome P. J. Coulton - Advanced Car Technology Systems

Although explicit finite element codes have been used for many years to predict the impact performance of plastic components, there are few papers that detail how the constants for material models were determined and the resulting models validated with experimental test results. Aliphatic polyetone materials appear very attractive materials for the developers of automotive fuel systems. This is principally due to their low fuel permeability and the stringent total vehicle evaporative requirements. This paper presents the analysis and results of the analysis of experimental test data to determine a material model for an aliphatic polyetone (Carilon EP) at high strain rates and low temperatures. Two different material models are compared (Johnson/Cook and Kruphowsky) with respect to their suitability to modelling Carilon EP and the chosen model validated with high speed impact tests.
THE IDENTIFICATION OF RATE-DEPENDENT MATERIAL PROPERTIES IN FOAMS USING LS-OPT
Heiner Müllerschön, Ulrich Franz, Thomas Münz - CAD-FEM GmbH, Nielen Stander - Livermore Software Technology Corporation

In the past years more and more complex materials, e. g. plastic and metallic foams, honey-comb materials, different types of glues, epoxy-glass materials etc., were incorporated in a wide range of products, particularly in the automotive industry. For the modeling of such materials within nonlinear dynamic problems numerous material models are available in LS-DYNA. However, the application of these material models require the knowledge of the ma-terial parameters describing the behavior of the specific material. The accuracy of the Finite-Element simulations depend authoritatively on the quality of the involved material parame-ters. In order to obtain these material parameters the calibration of the model is necessary through comparison with experimental data. The main objective of this paper is to demonstrate the calibration of a nonlinear material model by minimizing the difference of the model response and the experimental tests. As an example, a low density styrofoam is considered which is described by a material model with strain rate effects (Fu-Chang Model (LS-DYNA, 1999)). The minimization problem is solved via the Response Surface Method (Myers, 1995) using the commercial optimization code LS-OPT.
THE INFLUENCE OF RESIDUAL EFFECTS OF STAMPING ON CRASH RESULTS
Trevor Dutton, Paul Richardson, Andrew Knight, Richard Sturt - Ove Arup & Partners

The thickness changes and work hardening arising during the forming process are generally ignored in crash analysis. However, LS-DYNA offers a number of options for quantifying these effects. This paper sets out some recommended methods, and quantifies the effect of the forming process on crash response of a typical car of stamped steel construction. LS-DYNA can also be used for accurate stamping simulation, but in this study a one-step code was used, with the aim of finding the fastest method of generating and including the stamping data. The trade-off between the time taken and accuracy is examined.
USING CAE TO EVALUATE STRUCTURAL FOAM ALTERNATIVES IN B-PILLAR AND BUMPER DESIGNS
Sameer Gupta - Honda R&D, Americas, Inc.

This study examined the viability of using structural foam designs as lightweight alternative in B-pillar and bumper designs. The B-pillar was evaluated for side impact performance with respect to intrusion, while the rear bumper was evaluated for low speed impact performance with respect to intrusion and energy absorption. Typical stamped steel structures were used as baselines. Structural foam designs were evaluated using simulation and iterated until similar performance was achieved. Simulation results showed that the final design iteration of both the B-pillar and rear bumper achieved performance equivalent to the baseline with the benefit of reduced weight.
WEB-CENTRIC LS-DYNA
Henry H. Fong HPC Marketing – Enterprise Systems Products Sun Microsystems

The Internet has changed the way business is done – and High Performance Computing (HPC) is no exception. Many firms have launched “dot-com” software to facilitate B2B collaboration, outsource jobs, provide engineering services, or exchange data with suppliers and partners. Recently, however, hundreds of dot-coms have failed, and many high-tech companies have laid off thousands of workers. Now what? The term ASP (application service provider) has become popular in the past several years. ASPs deliver and manage applications and services remotely for multiple users – either through the Internet or a private network. An ASP owns the relationship with the end-user customer. Security tops the list of customers’ concerns. Hundreds of ASPs have sprung up, but most of these (e.g., Exodus, Qwest, Corio, EDS, Applicast, etc.) host computing services for commercial applications rather than technical ones. This paper introduces some basic concepts in portal supercomputing and ASPs, and suggests future directions LSTC and its worldwide distributors may wish to consider to web-enable LS-DYNA to make it accessible to a wider engineering community.