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6th European LS-DYNA Conference

Krystoffer Mroz, Bengt Pipkorn - Autoliv Development AB, Sweden
Initial evaluation of the particle method for mathematical out-of-position simulations was performed. The evaluation was carried out by means of static inflation and impactor tests. In the out-of-position load case, the occupant is initially positioned very close to airbag module and the interaction airbag-occupant occurs during the early deployment phase of the airbag. Thus a realistic representation of the folding pattern together with an ...
Methodology for Selection of Material Models for Plastics Impact Simulation
Hubert Lobo - DatapointLabs
The volume of plastics that are subjected to impact simulation has grown rapidly. In a previous paper, we discussed why different material models are needed to describe the highly varied behavior exhibited by these materials. In this paper, we cover the subject in more detail, exploring in depth, the nuances of commonly used LS-DYNA material models for plastics, covering important exceptions and criteria related to their use.
Mats Oldenburg, Per Salomonsson - Luleå University of Technology
Paul Åkerström, Greger Bergman - Gestamp Hardtech AB
In the manufacturing of ultra high strength boron steel components with the hot stamping process, it is of great importance that the final product will have the desired material properties. This is especially true for safety related automotive components. Often the preferred microstructure is a mix of martensite and bainite. In this work a model is developed and implemented in order to predict the austenite decomposition into ferrite, pearlite, ...
Model improvement during seat project
Christofer Karlsson, Scania CV AB
To help predict the behaviour of a seat assembly when performing a seat belt anchorage pull test (according to regulation ECE R14/05 and directive 76/115/EEC) a FE-model has been built and improved in several steps. To increase the accuracy of the simulation (quasi static), a number of modifications were made to the initial model. The adjustments include higher mesh density, allowing a better representation of the geometry. A tensile strength ...
Modeling Hailstone Impact onto Composite Material Panel Under a Multi-axial State of Stress
M. Anghileri, L. Castelletti, A. Milanese, A. Semboloni - Politecnico di Milano, Italia
Flying through a hailstorm is dangerous not only for the direct damages but also for the hidden damages which may concur to more serious accidents. In this work, hail impact onto composite structure under a multi-axial state of stress is investigated. Initially, a reliable model of a hailstone is developed referring also to the recent research on ice modelling. In parallel, a numerical model to predict delaminations in pre-stressed composite ...
Modelisation of screen rupture during a mobile phone free fall
C. Lacroix - Sagem Communication, Groupe Safran, France
Sagem brand mobile phone enjoys a strong presence in world markets thanks to continuous technological innovations associated to a high level of quality. We will approach here the case of the mobile phone screen (LCD), major part of a mobile phone whose integrity must be ensured throughout the life of the product. The specifications sheet specifies strict standards concerning the shock resistance: LCD should not be damaged during a series of 2 X ...
Modelling Carpet for Use in Occupant Crash Simulations
Dylan Thomas - Honda R&D Americas
Prediction of occupant injury using crash simulations can require numerical representation of materials that are not normally included within the structural model. Intuitively, it makes sense that the carpet would be required to predict the tibia index during frontal crash events; however, there appears to be little published on the topic. The tibia index is an injury criteria that needs to be predicted during IIHS frontal offset occupant ...
Odd Sture Hopperstad, Torodd Berstad, Odd-Geir Lademo, Magnus Langseth - Norwegian University of Science and Technology
Constitutive models and failure criteria for aluminium alloys have been formulated and implemented in LS-DYNA for corotational shell elements. The applications are largescale simulations of plastic forming and crashworthiness. The constitutive models include plastic anisotropy, non-linear isotropic and kinematic hardening, strain-rate effects and simple fracture criteria. A non-local instability criterion is used to determine the onset of strain ...
Jean Luc Lacome - LSTC Vincent Lapoujade Cril Technology – Groupe Alyotech
SPH, Smoothed Particle Hydrodynamics, is a very efficient tool to model industrial problems where large deformations occur. However, one disadvantage of the SPH technique is the expensive cpu cost compared to standard Finite Elements. Using the MPP version of LS-DYNA allows users to handle large problems (more than a million of particles) in a reasonable time. Due to the meshfree nature of the SPH method, standard decompositions used for finite ...
Multi-Scale Modeling of the Impact and Failure of Fiber Reinforced Polymer Structures using DIGIMAT to LS-DYNA Interface
L. Adam, R. Assaker and R. Ramaya - e-Xstream engineering S.A.
This paper deals with the prediction of the overall behavior of polymer matrix composites and structures, based on mean-field homogenization. We present the basis of the mean-field homogenization incremental formulation and illustrate the method through the analysis of the impact properties of fiber reinforced structures. The present formulation is part of the DIGIMAT [1] software developed by e-Xstream engineering. An interface between LS-DYNA ...
Multi-Scale Modelling of Textile Structures in Terminal Ballistics
Rimantas Barauskas - Kaunas university of technology, Lithuania
An efficient finite element model of the ballistic impact and perforation of the woven fabrics structures has been developed in LS-DYNA. The bullet has been considered as a deformable body in contact with the fabric package presented by interwoven yarn structure. The model of the weave has been created by presenting the multifilament yarns by thin shell elements the thickness of which represents the real thickness of yarns. The total model of ...
New developments in LS-OPT Version 3.2
Nielen Stander, Willem Roux - Livermore Software Technology Corporation
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
New Developments in the Compression of LS-DYNA Simulation Results using FEMZIP
Rodrigo Iza Teran, Clemens-August Thole, Rudolph Lorentz - Fraunhofer Institute for Algorithms and Scientific Computing SCAI
The standard usage of simulation as part of the automotive design process and increased computer power has increased the demand on archiving resources. This data may be reused several times during the development process and reused later for new models. Compression of the simulation results reduces both the archive size and the access times. This is why FEMZIP was developed several years ago. FEMZIP was specially designed for the compression of ...
Numerical Modelling and Biaxial Tests for the Mullins Effect in Rubber
William W. Feng, John O. Hallquist - Livermore Software Technology
The formulation, testing and numerical study of the Mullins effect on rubber are presented. Ogden first modelled the Mullins effect for studying the unloading in filled rubber. It has been extended here to include the Mullins effect on both unloading and subsequent loading. To demonstrate the Mullins effect experimentally, a new biaxial test, inflation of a plane circular membrane, is used. Some experimental test data are presented. An ...
Sunan HUANG, Jikuang YANG - Chalmers University of Technology, Sweden
Rikard FREDRIKSSON, Autoliv Research, Autoliv AB, Sweden
An active hood system was developed in Autoliv to minimize the head injury risk of pedestrians from impacts with car front. In order to detect the car-to-pedestrian impact in time, a contact sensor placed in the car bumper is needed. The stiffness of the bumper foam material is highly dependent on the environment temperature, which will result in unstable output from the contact sensor. A new pedestrian-bumper contact sensor was developed in ...
Optional Strain-Rate Forms for the Johnson Cook Constitutive Model and the Role of the Parameter Epsilon_0
Len Schwer - Schwer Engineering and Consulting Services
A brief review of the standard Johnson-Cook model is presented. Three optional strainrate forms are introduced and calibrated to laboratory data for A36 steel. Next a brief description of the LS-DYNA Version 971 implementation of the new strain-rate forms, within the existing viscoplastic formulation of the Johnson-Cook model, is presented. Finally, all four calibrated strain-rate forms are exercised in single element uniaxial stress test ...
Parameter identification for the simulation of debonding in honeycomb sandwich using LS-Dyna
M Hörmann - CADFEM GmbH
Performance of LS-DYNA with Double Precision on Linux and Windows CCS
Yih-Yih Lin - Hewlett-Packard Company
Although the majority of LS-DYNA jobs are simulated with single-precision arithmetic, the more accurate and robust double-precision arithmetic has to be used for certain situations. Currently, most public LS-DYNA benchmarks are with single precision and few with double precision. As a result, users often try to extrapolate the performance of LS-DYNA with double precision from that with single precision. This paper shows that such extrapolations ...
Practical Optimization for Automotive Sheet Metal Components
Xiao Chen, Omar Ghouati - Ford Research and Advanced Engineering Europe
Forming simulation has now reached an acceptable level of accuracy. It is possible to predict the hardening, the thinning and required forces for sheet metal stamped parts and it is also possible to predict the geometrical defects such as springback, wrinkling and surface appearance problems. Sheet metal forming can therefore be used in a closed loop to help design of parts and required tools in order to achieve a pre-defined geometry and ...
H. Müllerschön, D. Lorenz - DYNAmore GmbH
W. Roux - Livermore Software Technology Corporation
M. Liebscher, S. Pannier - TU Dresden
K. Roll - DaimlerChrysler AG
The purpose of this paper is to account for uncertainties in the manufacturing processes of metal forming in order to evaluate the random variations with the aid of FEsimulations. Various parameters of the Finite-Element model describing the investigated structural model are affected by randomness. This, of course, leads to a variation of the considered simulation responses such as stresses, displacements, and thickness reductions. On this, for ...
Probabilistic Assessment of a Stiffened Carbon Fibre Composite Panel Operating in its Postbuckled Region
D. Elder, R. Thomson - Cooperative Research Centre for Advanced Composite Structures Limited, Australia
This paper presents a probabilistic study on the behaviour and buckling capacity of a thin shell carbon fibre stiffened panel operating in its postbuckling region. The paper is a part of the ongoing world wide research into this phenomena being conducted by the CRC-ACS and many other interested parties including the EU FP6 Project COCOMAT. The aim of the research is to develop proven design methods that will allow an increased specific strength ...
Reduction of Acceleration Induced Injuries from Mine Blasts under Infantry Vehicles
Ala Tabiei, Gaurav Nilakantan - University of Cincinnati, USA
Anti tank (AT) mines and improvised explosive devices (IED) pose a serious threat to the occupants of infantry vehicles. The use of an energy absorbing seat in conjunction with vehicle armor plating greatly improves occupant survivability during such an explosion. The dynamic axial crushing of aluminum tubes constitutes the principal energy absorption mechanism to reduce the blast pulse transmitted to the occupant in this investigation. The ...
Road Safety Devices Assessment for Sliding Motorcyclists Protection
M. Anghileri, L. Castelletti, A. Milanese, M. Pirola, F. Pistochini - Politecnico di Milano, Italia
Statistics show that the impact with a roadside safety barrier of a motorcyclist sliding on the pavement after an accident is potentially more dangerous than the accident itself. In recent years, in effort to avoid the most serious consequences, the approach to barriers design changed and specific devices have been introduced to improve motorcyclists’ safety. At LAST Crash Labs, the effectiveness of one of these devices was experimentally and ...
Willem Roux - LSTC
Robust parameter design creates designs insensitive to the variation of specific inputs. The paper discusses the robust parameter design capability within the context of its implementation in LS-OPT version 3.2. The paper provides the following details: the fundamentals of robust parameter design, the design of experiments based methodology used in LS-OPT, and an example problem.
Robustness Evaluation Crashworthiness Simulation Results
Johannes Will - DYNARDO GmbH
Uli Stelzmann - CADFEM GmbH
The numerical robustness of simulation results from explicit time integration is an important topic. We know for real world applications of passive safety and crashworthiness that we have some numerical noise, but the interesting question is if that really does influence significantly our simulation results. Furthermore, today the robustness of the designs against naturally given input scatter, in loading conditions, geometry or material become ...
Rupture Modeling of Spot Welds Suitable for Crash FE Analysis in Vehicle Development Process
Koushi Kumagai, Masakazu Shirooka, Jirou Ohachi, Toshirou Ogawa - Toyota Motor Corporation
This paper describes the development of rupture modeling of spot welds suitable for crash FE analysis in vehicle development process. The authors presented a detailed spot weld rupture model called ‘spider web model’ in Toyota and confirmed that it closely correlates with actual full vehicle crash test results. Although, the spider web model is accurate, extensive effort is required to construct the model. Also, the spider web model can only ...
Seismic Modelling of an AGR Nuclear Reactor Core
Bruce Duncan,Berislav Kralj - Atkins
The work concerns the seismic response of an Advanced Gas-cooled Reactor (AGR) core. An LS-DYNA finite element model has been developed that represents each graphite brick. The contact between the bricks and their keys has been modelled with non-linear coaxial spring/dampers allowing for limited free motion. The model is a three dimensional representation of all the core layers and a neutron shield, making use of a symmetry by only modelling ...
Simplified modeling of thin-walled tubes with octagonal cross section - axial crushing
Yucheng Liu, Michael L. Day - University of Louisville
This article investigates the collapse characteristics of thin-walled tubes with octagonal cross sections during axial crushing. The tubes’ axial crushing resistance (the relationship between crushing force and axial deformation) is described with a series of mathematical equations, which are derived applying global energy equilibrium theory. The derived axial crushing resistance is then used for developing simplified finite element models for ...
Simulating the Complete Forming Sequence for a Roll Formed Automotive Bumper Beam
Trevor Dutton, Paul Richardson - Dutton Simulation Ltd
Matt Tomlin, Tom Harrison - Wagon Automotive plc
As part of the development of a new automotive bumper beam, a complete simulation of the entire forming process was carried out using LS-DYNA. The material for the beam was an ultra high strength steel presenting many challenges for the forming process. The sequence of forming operations was roll-forming (including forming a sweep in the initially straight roll-formed section), local annealing, forming of an initiator in the wall of the section ...
Simulation of a CMVSS 215 bumper pendulum test series with LS-DYNA
Armin Huß, Heiko Beck, Ingenieurbüro Huß & Feickert, Germany
In the course of an increasing automotive development for international markets many new loadcases have to be tested. The Canadian bumper pendulum test (CMVSS215) is one of these loadcases that form a special challenge for the simulation with LS-DYNA due to its sequential process. For this test four different bumper pendulums have to impact the vehicle, while with each new test the prior damages have to be taken over. Until now the simulation ...
Simulation of a Mine Blast Effect on the Occupants of an APC
A. Brill, B. Cohen - RAFAEL Ballistic Center, Israel
P. Du Bois, Consulting Engineer, Germany
In this paper the use of LS-DYNA for the simulation of a mine blast load on an armoured personnel vehicle is presented with comparison to a full test. The investigated vehicle is an M113 APC with occupants seated in commercial seats. Different approaches to the numerical analysis of this complicated event are presented and results are compared. In particular the blast load is applied using the standard engineering model (CONWEP) because of the ...
Simulation of acoustic and vibroacoustic problems in LS-DYNA using boundary element method
Ahlem Alia, Mhamed Souli - LSTC
James Hargreaves, Brian Walker - ARUP
Mojtaba Moatamedi - University of Salford
The present work concerns the new capability of LS-DYNA® in solving acoustic and vibroacoustic problems. In vibroacoustic problems, which are assumed to be weak acoustic-structure interactions, the transient structural response is computed first. By applying the FFT, it is transformed into a frequency response. The obtained result is taken as boundary condition for the acoustic part of the vibroacoustic problem. Consequently, the radiated noise ...
Simulation of containment-tests of fast-spinning rotors by explicit FEM
Thomas Winter - MAN B&W Diesel, Germany
Armin Huß, Heiko Beck - Ingenieurbüro Huß & Feickert, Germany
The objective of Containment Tests is to demonstrate that the housing of a turbocharger is of sound design and capable to satisfactorily contain fractured rotating parts inside the casing. As of yet these tests were carried out on a test bed during the type approval procedure of the turbochargers. On one hand this is very expensive and time consuming and, on the other hand, the comprehension of high-speed deformation processes is restricted as ...
Simulation of Masonry Wall Failure and Debris Scatter
Stuart C. McCallum, BAE Systems - ATC (Filton)
Paul M. Locking, Steve R Harkness, BAE Systems - Land (Shrivenham)
This paper outlines a methodology for the simulation of masonry wall failure and debris scatter. The aim of this work is to develop simulation techniques which can be used to assess and improve the design of building structures subject to high explosive loading. Masonry walls are constructed from bricks that are modelled as individual parts with tiebreak and single surface contact types. A key requirement of this work is to accurately predict ...
Yves de Lassat de Pressigny, Thierry Baylot - Centre d’Essais en Vol, Ministère de la Défense, France
The French Flight Test Centre in Toulouse (CEV Tl) made in 2004 prototype simulations of ground impact after airdrop (2d-40, 5th European LS-DYNA users conferences.) Its purpose was to enable the test centre to achieve parametric analyses of the shock level produced by airdrop with a combination of simulation and real tests, which was not feasible with tests only (because of the number of test cases required). Indeed a first proposal with ...
Sloshing response of a LNG storage tank subjected to seismic loading
Rosario Dotoli, Daniela Lisi, Danilo Bardaro - CETMA
Marco Perillo, Massimo Tomasi - EnginSoft
The number of Liquefied Natural Gas tanks is continually increasing. These tanks are very large and their capacity is about 150000[m3]. According to safety standards these kinds of tanks consist of an inner steel shell, containing the LNG, and an outer reinforced concrete shell. Nevertheless, they represent a great risk if they fail during an earthquake. Several types of tank failures have been observed. Tanks may be damaged for different ...
Peter Starke, Leonhard Mitterleitner - EADS Military Air Systems
This paper describes the application of LS – OPT for assessment of the influence of stochastic effects in bird strike events. To address the problem, a two – step approach has been chosen. In the first step, LS – OPT has been used in order to automatically determine the penetration velocities for different impact sites. In a second step, LS – OPT was used to create a response surface from the calculated penetration velocities. Subsequently, for ...
Some observations on failure prediction in sheet metal forming
Mats Larsson - Saab Automobile, Sweden
Kjell Mattiasson - Chalmers Univ. of Technology, Sweden
Mats Sigvant -Volvo Cars Manuf. Engng., Sweden
This paper presents results from a FE-study on failure prediction in ductile metal sheets. The studied material, a DP600 dual phase steel, is used throughout the study. The effects of variation of element sizes, material parameters, and friction are shown and discussed. Also results from simulations of in-plane and out-of-plane tests are compared and discussed.
Spotweld Failure Prediction using Solid Element Assemblies
Skye Malcolm - Honda R&D Americas Inc.
Emily Nutwell - Altair Engineering
One current methodology for spotweld modelling utilizes a tied contact to connect the weld elements to the components. In order for this contact to be robust and acceptably mesh independent, multiple solid elements are needed to represent a single weld. Several studies were conducted which concluded that a cluster of eight hex elements provides significantly improved performance over a single beam or hex element. However, ease of use is critical ...
Springback analysis in Andvanced High Strength Steel using a new flexible semi-industrial tool geometry, the flex-rail
A. Andersson - Volvo Cars Body Components, Sweden
The automotive industry is using more and more of Advanced High Strength Steel in order to reduce the weight of the car. Since this will generate more springback, it is of vital importance to be able to predict the amount of springback in the parts. Otherwise, many late changes have to be made in order to fit the parts in their position. In order to increase the ability to understand and test the behavior of the springback in sheet-metal parts, ...
Michael Öman - Linköping University, Sweden
This paper discusses the problem of structural optimization in product family design and different methodologies are evaluated for weight optimization of components that are common for members in the family. First, the benefits of product family design are presented, followed by a discussion of the complexity of the design problem when the product family is exposed to crash loading and multiple load cases. It is concluded that in large problems ...
Ingrid Skogsmo - Director Volvo Cars Safety Centre
Safety has been a Volvo cornerstone from its founding in 1927, and has remained a fundamental core value since. Within the Ford Motor Company, Volvo Cars has been appointed Centre of Excellence for safety. Continuous development and expansion of the concept of automotive safety involve visionary ideas build on earlier innovative passive and active safety approaches to deliver new "intelligent" solutions designed to neutralize risks of driver ...
Uncertainty Assessment with Stochastic Simulation in Aircraft Cabin Development
D. Vogt,R. Hartnack,M. Olbert - EADS Innovation Works
J. Schlattmann, Hamburg University of Technology
To fulfill the need for shorter development cycles in modern product development the increased use of computer-aided engineering is one possibility. While the numerical calculation of a model leads to one single solution, the behavior of systems in the real world is never exactly repeatable due to tolerances and natural scatter in the system parameters. The assessment of the resulting uncertainties is of great importance for systems requiring a ...
Using LS-Dyna as an Aid to the Inclusive Design of Child Resistant Closures
Joe Luxmoore, Dr. Alaster Yoxall - University of Sheffield
The population of most developed countries is ageing. Despite continuing medical advances, ageing brings with it a host of issues, not least a loss in strength and dexterity. One major area of concern is the ability of elderly consumers to access packaged goods such as food and medicines. In previous studies, the authors developed an LS-Dyna model of a human hand that was used to investigate the effect of physical dimensions and the choice of ...
Forsberg Jimmy, Björkman Gunnar - VTEC
This paper summarizes the experiences of using the LSTC environment in a multiattribute optimization. The work was carried out in an on-going project, SuperLIGHTCar (SLC), which aims to reduce the weight of the body in white (BIW) of a compact class car by at least 30%. This objective is made possible by using new materials and a blend of materials in the design. The car should still fulfil user rating, e.g. Euro NCAP demands but also demands of ...
Using LS_DYNA to find Failure modes during design process
Dr. Tayeb Zeguer - Jaguar and Land Rover
Understanding the customer needs Failure Mode List Generation Detection using CAE – Capability and Enablers CAE Execution Process and the use of DFSS principles Conclusions
P.K.C. Wood, C.A. Schley - University of Warwick
M. Buckley - Jaguar and Land Rover
B. Walker - ARUP
T. Dutton - Dutton Simulation
A thin-wall open channel beam, fabricated from high strength Dual Phase sheet steel, subjected to 3-point bending and constant velocity boundary condition, is investigated to validate material performance for automotive crash applications. Specifically quantitative validation of material tensile data determined from high speed tests and component models, and qualitative validation of materials resistance to fracture. The open channel beam is ...
Virtual Modelling of Motorcycle Safety Helmets: Practical Problems
Alessandro Cernicchi, Ugo Galvanetto, Lorenzo Iannucci - Imperial College London
Motorcycle helmets are safety devices that can be optimised to perform better in different impact configurations. It is not easy to determine the mechanical properties of a particular model of helmet which maximise its effectiveness in real impact conditions and it is not surprising that most helmet producers use empirical design procedures and assess the effectiveness of their products by carrying out numerous experimental impact tests. The ...
Gunnar Björkman,Jimmy Forsberg - Volvo Technology
Jan Engström - SCH Incubator AB
With the ever increasing capability in computer power, optimizing a full vehicle structure including most of the crash load cases will be a real possibility in the near future. For example, the Cell chip used in PS3 or the availability of recent GPU of high end PC graphics cards delivers 100 – 1000 GFLOPS. The bottleneck in this scenario will not be the computer power, instead the problem will be how to feed the computers with models and input ...
Marco Anghileri, Luigi Castelletti, Edoardo Francesconi - Politecnico di Milano, Italia
The outcomes of a research focusing on water modelling and fluid-structure interaction, are here presented. A number of water impact drop tests using a typical aircraft skin panel were performed. The tests were numerically reproduced modelling the fluid region using the two meshless methods implemented in LSTC/LS-Dyna 971: the Smoothed Particle Hydrodynamics and the Element Free Galerkin method. The accuracy of the models was evaluated referring ...