http://www.dynalook.com daily 1 2009-03-06T17:29:14Z http://www.dynalook.com/european-conf-2007/Developments-in-Occupant-and-Seat-Modelling-with.3.pdf There is constant pressure to reduce the time needed to process design data into crash results (mesh, assemble, create different crash cases, check, run, post-process). The meshing step has been reduced by batch meshing technology, and progress has been made in several other areas such as automatic post-processing. Attention is now turning to the remaining bottlenecks, which include occupant and seat positioning. These steps require careful manual work and cannot currently be automated. The problem is magnified by the large number of seat position/dummy combinations. • It is intended that Primer Version 9.3 will solve these problems, by providing fast methods of dummy positioning, seat positioning, seat foam compression, and belt fitting. No publisher mike 2009-03-23T14:25:24Z File http://www.dynalook.com/european-conf-2007/New-developments-in-LS-OPT-Version-3.2.pdf An overview of LS-OPT features is given with special emphasis on the major new optimization features available in LS-OPT Version 3.2. These include GUI support for parameter identification, confidence intervals for individual optimal parameters, point plotting as an enhancement to 3-D metamodel plotting, matrix expressions, coordinatebased result extraction and retry features for job distribution No publisher mike robust design optimization ls-opt 2009-03-23T14:24:51Z File http://www.dynalook.com/european-conf-2007/a-comparative-review-of-damage-and-failure-models.pdf Reliable prediction of damage and failure in structural parts is a major challenge posed in engineering mechanics. Although solid material models predicting the deformation behaviour of a structure are increasingly available, reliable prediction of failure remains still open. With SAMP (a Semi-Analytical Model for Polymers), a general and flexible plasticity model is available in LS-DYNA since version 971. Although originally developed for plastics, the plasticity formulation in SAMP is generally applicable to materials that exhibit permanent deformation, such as thermoplastics, crushable foam, soil and metals. In this paper, we present a generalized damage and failure procedure that has been implemented in SAMP and will be available in LS-DYNA soon. In particular, important effects such as triaxiality, strain rate dependency, regularization and non-proportional loading are considered in SAMP. All required physical material parameters are provided in a user-friendly tabulated way. It is shown that our formalism includes many different damage and failure models as special cases, such as the well-known formulations by Johnson-Cook, Chaboche, Lemaitre and Gurson among others. No publisher mike 2009-03-23T13:44:23Z File http://www.dynalook.com/european-conf-2007/a-functional-bayesian-method-for-the-solution-of.pdf A Functional Bayesian (FB) methodology is introduced for the calibration of constitutive parameters spatially distributed within a model. The probabilistic solution to the inverse problem consists of assimilating the uncertainty captured from the actual material responses into the material parameters. A case study is introduced to illustrate the applicability of the method, where a soil model built in LS-DYNA is parameterized using surface displacement fields read from stereo digital images taken during a series of triaxial tests performed under similar conditions. The implementation of the FB method yields probability density functions of the parameters and its corresponding correlation structure. The parameters field is efficiently sampled using the Polynomial Chaos Decomposition method (PC) which allows for spatial non-stationary and nonGaussian material representations. The posterior integration is performed via Markov Chain Monte Carlo techniques. Results show extended inferences about the material behaviour due to probabilistic description of the material variability. No publisher mike stochastic monte carlo 2009-03-23T14:05:26Z File http://www.dynalook.com/european-conf-2007/a-new-impact-scenario-for-p-v-tram-certification.pdf Tram crashworthiness is getting a more and more demanding issue. Simulations carried out to verify that the new tram AnsaldoBreda Sirio-Milano fulfils the prEN 15227 requirements for certification are here described. Besides a new impact scenario with characteristics closer to trams accidents is proposed. Structural enhancements so that the tram fulfils also the more severe impact condition of the new scenario are introduced. No publisher mike 2009-03-23T12:53:50Z File http://www.dynalook.com/european-conf-2007/accurate-and-efficient-dummy-models-for-occupant.pdf No publisher mike 2009-03-23T14:25:17Z File http://www.dynalook.com/european-conf-2007/advanced-finite-element-model-for-ae-mdb-side.pdf This paper represents a new Finite Element simulation model for AE-MDB v3.9 side impact barrier and proposes a method on creating suitable assumptions and material data. Cellbond AE-MDB barrier investigation was carried out to produce an advanced FE model. Experimental Flat Wall and Offset Pole test results were used to validate the accuracy of the developed models. The explicit LS Dyna 3D code was used to model the geometries, and the Material Card data was obtained from several static compressive tests at different angles to characterize the yielding function of the aluminum honeycomb parts. The dynamic models were also validated by a Flat Wall test which represents the crash performance of AE-MDB barrier. For dynamic tests the barrier was mounted on a mobile trolley and it was tested at speed of 35 km/h. In Offset Pole test, the AE-MDB barrier was subjected to an asymmetric crush with a rigid vertical pole in which test speed was 20 km/h. The final comparison of the overall results demonstrates a good correlation between test data and CAE results for both the Flat Wall and Offset Pole tests. No publisher mike 2009-03-23T12:31:05Z File http://www.dynalook.com/european-conf-2007/advanced-simulations-of-cellular-structures-with.pdf Cellular structures have an attractive combination of physical and mechanical properties and are being increasingly used in modern engineering applications. In this study the influence of different parameters (type of base material, type of pore filler, relative density, size of the cellular structure, strain rate) on behaviour of open- and closed-cell cellular structures under impact loading was investigated by means of computational simulations using the explicit finite element code LS-DYNA. The influence of gas filler inside the closed-cell cellular structure was analysed using the representative volume element and the airbag model. The analysis of the fluid filler behaviour inside the opencell cellular structures was done with combination of the Finite element method and the Smoothed particle hydrodynamics meshless method. The base material properties and macroscopic behaviour of cellular structures with and without fillers were determined with experimental measurements of appropriate specimens under quasi-static and dynamic uniaxial loading conditions. Computational simulations show that the base material has the highest influence on behaviour of cellular structures under impact conditions. The increase of relative density and strain rate results in increase of the cellular structure stiffness. Parametric computational simulations have also confirmed that the filler influences macroscopic behaviour of the cellular structures, which depends on the loading type and the size of cellular structure. In open-cell cellular structures with higher filler viscosity and higher relative density, increased impact energy absorption is observed. No publisher mike 2009-03-23T14:05:55Z File http://www.dynalook.com/european-conf-2007/advances-in-adaptive-thermal-mechanical-metal.pdf The vision of LS-DYNA is to become multiphysics and adaptive. LSTC endeavours to make the LS-DYNA code as complete, accurate and easy to use as possible. This contribution evaluates the features for adaptive thermal-mechanical simulations that are in recent LS-DYNA versions with a focus on implicit 3D. Implicit solutions do not need mass scaling as explicit forming simulations often use. Implicit element free Galerkin (EFG) elements are successfully used for a bulk metal forming test case (upsetting with a non-trivial stamp) with adaptive remeshing of tetrahedrons. The interplay of adaptive remeshing with the contact algorithm is highlighted. Additionally plastic heating of 3Dshells in a deep drawing benchmark example is assessed Some remarks regarding the features for post-processing adaptive simulations with full remeshing in LS-PrePost are evaluated. No publisher mike 2009-03-23T13:45:23Z File http://www.dynalook.com/european-conf-2007/airbag-simulation-with-ls-dyna-past-2013-present.pdf During the last decade the simulation of the airbag deployment process has become a standard application of explicit finite element codes. At the beginning of the development the focus was to capture the influence and improve the results of dummy impact on fully inflated airbags. Later the deployment kinematics of folded airbags, different folding techniques and vent-hole design became more and more important. With the requirement to comply with FMVSS 208, i.e. Out-of-Position load cases, it became apparently necessary to include the interaction between the internal gas flow and the fabric airbag structure. Hence coupled algorithms that allow for interaction between the discretized gas flow and the airbag structure were the main focus during the past five years. The present paper aims to sketch the development history of airbag deployment simulations from the very beginning of the late 1980s to the current, highly sophisticated models available in LS-DYNA. Different modelling techniques will be shown and their advantages, drawbacks and the necessary effort to gain useful results will be discussed. No publisher mike 2009-03-23T13:44:21Z File http://www.dynalook.com/european-conf-2007/ale-modeling-of-surface-waves.pdf An Arbitrary Lagrange Euler formulation for the propagation of surface waves is developed in LS-DYNA®. The ALE computational time step in this code is divided in two cycles: a Lagrangian cycle in which the mesh follows the material deformation and an advection cycle in which the users through remapping algorithms control the mesh motion. The new feature presented in this paper is one of these remapping algorithms. It enables a Lagrangian behavior of free ALE mesh boundaries whereas, in the direction of the wave propagation, the ALE mesh is Eulerian to avoid distortions. Nodes on the ALE mesh borders moves with the surface waves during the Lagrangian cycle. During the advection cycle, the remap positions of these nodes are computed by interpolating the Lagrangian positions of their neighbors with biquadratic polynomials. If the wave amplitudes are too important, ALE smoothing can be used for the internal nodes and a specific smoothing is applied on the mesh surfaces. No publisher mike 2009-04-07T12:15:07Z File http://www.dynalook.com/european-conf-2007/application-of-shell-honeycomb-model-to-iihs-mdb.pdf This paper describes a new finite element modeling method of Aluminum honeycomb using shell elements. It is our new modeling method that cell size of honeycomb structure is enlarged to increase time step size for FEM analysis, and compressive strength is controlled by thickness of shell elements. New modeling method was applied to IIHS moving deformable barrier model, and side impact analysis with a full vehicle model was performed. The result of simulation using a new barrier model showed much better correlation with a test result than previous simulations. No publisher mike 2009-03-23T12:31:03Z File http://www.dynalook.com/european-conf-2007/concept-design-of-an-a-pillar-mounted-airbag-for.pdf Accident investigations have shown that in pedestrian-versus-vehicle accidents, windshield edges, A-pillars, cowls are the main sources for severe head injuries due to their high stiffness. To mitigate head injury severities, it is necessary to improve the safety performance of these structures. An A-pillar mounted airbag system (AMAS) was devised with the aim to prevent head from directly impacting against stiff structures such as A-pillars, windshield frames and edges. The airbags of the AMAS are installed inside A-Pillars. When a car strikes with a pedestrian, the airbag will break the A-Pillar cover and deploy along the whole APillar to cover the stiff structures. In this study, the safety performance that can be provided by this system was evaluated by mathematical simulations. A finite element (FE) Ford Taurus car model and an EEVC headform model were used to simulate the pedestrian headform tests as proposed by EEVC. FE airbag models were developed and the influence of airbag parameters, including airbag type, inflow mass rate, vent size and deploy timing, were investigated by mathematical simulations. The safety performance of the AMAS was also evaluated by an FE human head model. The results show that this system can greatly reduce the head injury severity in case a pedestrian head impacts with A-pillar areas. No publisher mike 2009-04-07T12:14:35Z File http://www.dynalook.com/european-conf-2007/contact-and-sliding-simulation-of-rubber-disk-on.pdf It is crucial to obtain detailed information about frictional interaction between tire and road surface to estimate performance of vehicle brake system or tire on real road surface. Simulation using Finite Element Method (FEM) in addition to experimental procedure is regarded to be useful to investigate contact behavior between tire and road surface. However, indeed, it is difficult to apply FEM simulation for such a problem since contact and sliding of rubber on rough rigid road surface may cause local large element distortion on rubber material and simulation may fail by negative volume error. In this paper, modeling of a rubber disk and rigid road surface with microscopic roughness, which can be used as a baseline for simulation of contact behavior between tire and road surface, is described. Some investigation for analysis technique to ensure stable computation of rubber disk and road surface model under severe condition has been made. It was shown that proposed modeling technique could avoid extreme mesh distortion during simulation. It is expected that the proposed technique can be used in simulation of rolling/sliding tire on real road surface. No publisher mike 2009-03-23T12:31:00Z File http://www.dynalook.com/european-conf-2007/corpuscular-method-for-airbag-deployment.pdf No publisher mike 2009-04-07T12:14:28Z File