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Papers submitted personally by authors

Recent Developments in Damage and Failure Modeling with LS-DYNA
Haufe, A., Neukamm, F., Feucht, M., Du Bois, P., and Borvall, T.
2010 Nordic LSDYNA Users Forum, Gothenburg, Sweden, October, 2010.
OBSERVATIONS DURING VALIDATION OF SIDE IMPACT DUMY MODELS - CONSEQUENCES FOR THE DEVELOPMENT OF THE FAT ES-2 MODEL
Ulrich Franz, Werner Schmid, Peter Schuster - DYNAmore GmbH
Detailed finite element side impact dummy models of the USSID and EUROSID have been developed in cooperation with the German Association for Automotive Research (FAT) dur- ing the last 5 years. Both models are validated using tests at material and component levels as well as fully assembled models. The development of the LS-DYNA dummy models has been performed by the authors. Both models are used by nearly all car manufacturers ...
DEVELOPMENT OF A COUPLED FINITE ELEMENT AND MESH-FREE METHOD IN LS-DYNA
Cheng-Tang Wu - Livermore Software Technology Corporation
Mark E. Botkin, Hui-Ping Wang - GM R & D Center
A coupled finite element and mesh-free method for the solid and structure analysis has been proposed. This method is developed to minimize the mesh distortion problems encountered in the finite element analysis and to reduce the high CPU cost associated with the mesh-free computation. To couple the mesh-free method with the LS-DYNA, an interface constraint has been developed. This interface constraint is introduced onto the interfaces ...
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, ...
ON THE ROBUSTNESS OF A SIMPLE DOMAIN REDUCTION SCHEME FOR SIMULATION-BASED OPTIMIZATION
Nielen Stander - Livermore Software Technology Corporation
K.J. Craig - Multidisciplinary Design Optimization Group (MDOG)
This paper evaluates a Successive Response Surface Method (SRSM) specifically developed for simulation-based design optimization, e.g. that of explicit nonlinear dynamics in crashworthiness design. Linear response surfaces are constructed in a subregion of the design space using a design of experiments approach with a D-optimal experimental design. To converge to an optimum, a domain reduction scheme is utilized. The scheme requires only ...
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 ...
MULTIDISCIPLINARY DESIGN OPTIMIZATION OF AUTOMOTIVE CRASHWORTHINESS AND NVH USING RESPONSE SURFACE METHODS
K.J. Craig - Multidisciplinary Design Optimization Group
Nielen Stander - Livermore Software Technology Corporation
D.A. Dooge - Advanced Vehicle Engineering
S. Varadappa - Quantum Consultants
This paper describes the multidisciplinary design optimization of a full vehicle to minimize mass while complying with crashworthiness and Noise, Vibration and Harshness (NVH) constraints. A full frontal impact is used for the crashworthiness simulation in the nonlinear dynamics code, LS-DYNA. The NVH constraints are evaluated from an implicit modal analysis of a body-in-white vehicle model using LS- DYNA. Seven design variables describe ...
MATERIAL IDENTIFICATION IN STRUCTURAL OPTIMIZATION USING RESPONSE SURFACES
Nielen Stander - Livermore Software Technology Corporation
K.J. Craig - Multidisciplinary Design Optimization Group (MDOG
H. Müllerschön - CAD-FEM GmbH
R. Reichert - DaimlerChrysler
This paper evaluates the use of a response surface optimization algorithm for structural material or parameter identification. The algorithm used is the Successive Response Surface Method (SRSM) as implemented in LS-OPT. Two methods are used in the formulation of the optimization problem. The first is to minimize the maximum deviation of the distance function between the simulated and experimental results at selected points, while the ...
An Optimization Procedure For Springback Compensation Using LS-OPT
Nielen Stander, Mike Burger, Xinhai Zhu, Bradley Maker - Livermore Software Technology Corporation
The purpose of this study is to develop a methodology for springback compensation in sheet metal stamping operations. An optimization method is employed to minimize the difference between the simulation results and the intended design. This procedure results in an optimized die shape. LS-DYNA, LS-OPT and TrueGrid are used to input original tool geometry, material, and process parameters, identify design variables, perform springback ...
RESPONSE SURFACE AND SENSITIVITY-BASED OPTIMIZATION IN LS-OPT: A BENCHMARK STUDY
Nielen Stander - Livermore Software Technology Corporation
K.J. Craig - Multidisciplinary Design Optimization Group
This paper evaluates the robustness of LS-OPT for response surface and design sensitivity-based optimization. The methodology uses linear response surfaces constructed in a subregion of the design space. These are constructed using either a design of experiments approach with a D-optimal experimental design or the available analytical or numerical gradient. The approach utilizes a domain reduction scheme to converge to an optimum. The scheme ...
New LS-DYNA Fluids Solvers
Grant O. Cook, Jr.., Zeng-Chan Zhang - Livermore Software Technology Corporation
This paper discusses two new fluid solvers that will be included with releases of LS-DYNA after LS960. The first one is a new compressible solver based upon the Space-Time Conservation Element and Solution Element Method (or the CE/SE method for short), and the second one is an incompressible fluid FEM solver.
Processing of Equality Constraints for Implicit in LS-DYNA v. 970
C. Cleve Ashcraft, Roger G. Grimes, Bradley N. Maker - Livermore Software Technology Corporation
LSTC is committed to building an implicit capability into LS-DYNA that is as capable as the flagship explicit capability. Over the years LSTC has added many different types of constraint handling capabilities in explicit that now have to be handled by implicit. The vast majority of these constraints are equality constraints imposed on the linear or nonlinear solution required at each time step. We will describe a new approach for handling ...
Input Parameters for Metal Forming Simulation using LS-DYNA
Bradley N. Maker, Xinhai Zhu - Livermore Software Technology Corporation
LS-DYNA has been widely used to study automotive crash. Default input parameters are generally chosen to give efficient, accurate crash simulation results. These defaults are not necessarily optimal for metal forming simulations. The following presents a standard procedure for conducting metal forming simulations with LS-DYNA. Recommended input parameters are identified in boldface type and included in boxed keyword input syntax for quick ...
Two-Stage Stochastic and Deterministic Optimization
Tim Rzesnitzek, Dr. Heiner Müllerschön, Dr. Frank C. Günther, Michal Wozniak
The purpose of this paper is to explore some interesting aspects of stochastic opti- mization and to propose a two-stage optimization process for highly nonlinear automotive crash problems. In the first stage of this process, a preliminary stochastic optimization is conducted with a large number of design variables. The stochastic optimization serves the dual purpose of obtaining a (nearly) optimal solution, which need not be close to ...
From complex 3D-foam parts to ready LS-DYNA inputdata in less than one hour? Examples from occupant simulation at Daimler Chrylser
Andreas Hirth - Daimler Chrysler
Paul Du Bois - consulting engineer
 
Comparison of different element types in structural analysis
K. Elsäßer,C. Pedrazzi - TRW Automotive
B. Keding, H. Müllerschön - DYNAmore GmbH
Components for occupant restraint systems usually undergo structural analysis before hardware prototypes are made. In most cases the simulation is nonlinear in geometry, material and boundary conditions. Additionally, the load case often is highly dynamic. For this purpose explicit FEM is a suitable tool. It is well known, that the accuracy of deformations and especially stresses has to be checked carefully in some cases. Therefore, a ...
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 ...
Multi-Objective Optimization Using LS-OPT
Goel T., Stander N.
Most engineering optimization problems have more than one objective. Often these objectives conflict such that no single solution can be considered optimum with respect to all objectives. Then, the optimum to this problem is a set of solutions known as Pareto optimal set....
On the Robustness of a Simple Domain Reduction Scheme for Simulation-Based Optimization
Stander N., Craig K.J. - Livermore Software Technology Corporation
This paper evaluates a Successive Response Surface Method (SRSM) specifically developed for simulation-based design optimization, e.g. that of explicit nonlinear dynamics in crashworthiness design. Linear response surfaces are constructed in a subregion of the design space using a design of experiments approach with a D-optimal experimental design...
Comparison of different element types in structural analysis
K. Elsäßer,C. Pedrazzi - TRW Automotive
B. Keding, H. Müllerschön - DYNAmore GmbH
Components for occupant restraint systems usually undergo structural analysis before hardware prototypes are made. In most cases the simulation is nonlinear in geometry, material and boundary conditions. Additionally, the load case often is highly dynamic. For this purpose explicit FEM is a suitable tool. It is well known, that the accuracy of deformations and especially stresses has to be checked carefully in some cases. Therefore, a ...