http://www.dynalook.com daily 1 2009-06-22T08:19:09Z http://www.dynalook.com/european-conf-2009/A-I-01.pdf In this presentation Dr. John O. Hallquist, founder and president of Livermore Software Technology Corporation (LSTC), will give an overview about recent developments in LS-DYNA. LS-DYNA is a highly advanced general-purpose nonlinear finite element program that is capable of simulating complex real world problems. The distributed memory solver provides very short turnaround times on Unix, Linux and Windows clusters. The major development goal of LSTC is to provide within LS-DYNA capabilities to seamlessly solve problems that require • "MULTI-PHYSICS", • "MULTIPLE STAGES", • "MULTI-PROCESSING". Its fully automated contact analysis capabilities and error-checking features have enabled users worldwide to solve successfully many complex crash and forming problems. LSTC develops sophisticated tools for modeling and simulating the large deformation behavior of structures. In addition to LS-DYNA the tools LS-PREPOST for pre - and post-processing, and LS-OPT for optimization are developed by LSTC. The main applications are: • Large Deformation Dynamics and complex Contact Simulations • Crashworthiness Simulation • Occupant Safety Systems • Metal Forming • Explicit/ Implicit Analysis • Metal, Glass, and Plastics Forming • Multi-physics Coupling • Failure Analysis • Sophisticated Material Models • Fluid-Structure Interaction • SPH (Smooth Particle Hydrodynamics) • EFG (Element Free Galerkin) LSTC was founded in 1987 by John O. Hallquist to commercialize as LS-DYNA the public domain code that originated as DYNA3D. DYNA3D was developed at the Lawrence Livermore National Laboratory, by LSTC’s founder, John O. Hallquist. No publisher admin 2009-05-28T21:05:42Z File http://www.dynalook.com/european-conf-2009/A-I-02.pdf Wood is one of the oldest construction materials known to man. Over thousands of years it has been mainly used in a craft framework, so that current design rules are often based on experience and tradition. The scientific knowledge about the material behavior is often surprisingly poor. In order to exploit the extraordinary ecological potential of the material and to enable its structural use also in an industrial framework, improved material models are required. Modern timber construction is characterized by increasing demand of two- and three dimensional bearing components. Dimensioning and design of such sophisticated structures require powerful material models for numerical simulation tools such as the finite element (FE) method. Moreover, the large variability of the macroscopic material properties has to be understood and suitably described to prevent exaggerated safety factors resulting in an uneconomic over-dimensioning of timber members. In order to understand the variability of macroscopic properties of solid wood and the underlying phenomena and to suitably describe them in material models, the hierarchical microstructure of the material has to be considered. At sufficiently small length scales universal constituents common to all wood species and samples as well as universal building principles can be identified. Namely, lignin, hemicellulose, cellulose, and water are such tissue-independent universal constituents with common mechanical properties across the diverse wood species at the molecular level. They build up cell walls resembling fiber-reinforced composites, which are arranged according to a honeycomb pattern. A mathematical formulation of the univeral building principles results in a multiscale micromechanical model for wood which links microstructural characteristics of individual wood samples to macroscopic mechanical characteristics of these samples. Homogenization techniques are employed for this purpose. In particular, the composite structure of the wood cell wall motivates application of continuum micromechanics for estimation of its elastic properties. At the cellular scale, plate-type bending and shear deformations dominate the mechanical behavior, which are more suitably represented by a unit cell approach. Formulation of the localization problem corresponding to the multiscale homogenization scheme allows determination of strain estimates at smaller length scales for given macroscopic loading. Quadratic strain averages (so-called ‘second-order estimates’) over microstructural components turned out to suitably characterize strain peaks in these components. Combination of estimates for such averages with microscale failure criteria delivers predictions for macroscopic elastic limit states. As for solid wood, experimental investigations indicate that wood failure is initiated by shear failure of lignin in the wood cell wall. This can be suitably described mathematically by means of a von Mises- failure criterion. The multiscale models for wood stiffness and elastic limit states are validated by comparison of model predictions for stiffness and strength properties with corresponding experimental results across a multitude of different wood species and different samples. The small errors of the model predictions underline the predictive capabilities of the micromechanical model. For example, the mean prediction errors for the elastic moduli and the shear moduli related to the three principal material directions L, R, and T are each below 10 %. The capability of micromechanical approaches to link macroscopic properties to microstructural characteristics renders such approaches also very appealing for wood products. In this paper, models for a representative of strand-based products, namely the Veneer Strand Board (VSB), as well as for a representative of solid wood-based products, namely the DendroLight panel, are shown. VSB consists of large-area, flat and slender strands with uniform strand shape and dimensions and is typically built up of several layers with different strand orientations. The high-quality strand material results in increased stiffness and strength of the board compared to conventional strand and veneer- based panels. The multiscale model for VSB spans three scales of observations: the strand material, a homogeneous board layer, and the multi-layer board. Continuum micromechanics is applied first in order to estimate the elastic properties of a homogeneous board layer from the stiffness of the strands, their shapes, and their orientations. In the second step, effective stiffness properties of a multi-layer panel are determined by means of classical lamination theory. Thereby, the stacking sequence, the orientation of the principal material directions of the single layers, and the density variation across the board thickness are taken into account. Model validation is again based on independent experiments. Results of tests on specially produced homogeneous boards as well as inhomogeneous boards with a well defined vertical density distribution show a good agreement with corresponding model predictions. This underlines the capability of the model for estimation of the stiffness of strand-based engineered wood products from microstructural features and renders it a powerful tool for parameter studies and product optimization. DendroLight is a three-layered lightweight panel consisting of thin outer layers of solid wood or particle board and a middle layer made up of small cells with webs inclined by an angle of 45° facing alternatively upwards and downwards. The periodic microstructure motivates application of the unit cell method for prediction of the mechanical behavior of this panel. As for plane periodic media, macroscopic unit curvature states are considered as loadings of the unit cell in addition to macroscopic unit strain states. In particular, effective in-plane stiffnesses and bending stiffnesses are obtained. For the purpose of model validation, several panel samples were produced by hand and tested in tension. The experimental results show a good agreement with corresponding stiffness predictions by the model. The multiscale model has already been successfully employed for product characterization and further product development. Since wood is a naturally grown material, it shows growth irregularities, primarily knots and site-related defects. Knots result in a pronounced reduction of stiffness and strength of wooden boards. Due to the highly anisotropic material behavior of wood, the influence of the grain orientation on the mechanical properties of a board is very pronounced and results in high variability in strength and stiffness of structural timber. The latter is a major difficulty in solid wood utilization and brings about the need for wood grading. This motivates investigation of the effects of knots on the mechanical behavior of boards by means of physically-based numerical simulations. In particular, the FE method is combined with sophisticated models for the fiber course and the material behavior. For the description of the local fiber course around a knot, a mathematical algorithm based on a fluid flow approach and polynomial functions fitted to the annual ring course is employed. The algorithm is evaluated at every integration point of the FE model and yields the local three-dimensional fiber orientation there. With respect to the mechanical material behavior, the previously described micromechanical model for solid wood is used, enabling consideration of local variations of microfibril angles or chemical composition of the wood tissue in the vicinity of knots. First results obtained with the numerical simulation tool indicate its capability to estimate the stiffness and strength reduction of wood boards in consequence of knots. On the whole, micromechanical models provide accurate estimates for the mechanical properties of wood and wood products in a fully three-dimensional and orthotropic framework. Also various couplings, e.g. between moisture transport and mechanical behavior, are suitably captured by these models. This makes these models highly valuable for structural simulations, whose predictive and also descriptive capabilities are often limited by the lack of suitable input data or the poor accuracy of available data. Hence, micromechanical modeling activities are expected to support structural analyses of wood structures, but also optimization of processes in wood drying technology. No publisher admin 2009-05-28T16:08:54Z File http://www.dynalook.com/european-conf-2009/A-I-04.pdf Nowadays the engineering and planning process in sheet metal forming is fundamentally supported by CAD and CAE systems. Beside the full 3D design process of parts and tools the simulation of sheet metal forming processes has established itself in the last 15 years within standard industrial practises. Nevertheless the virtual engineering and planning consists of more than just CAD and CAE tools. For a coordinated and effective process it is recommended to make use of the so-called process chain model. Therewith the interactions between different technologies or single processes can be taken into account. The process chain “Painted Car Body” consists of geometry and functionality development as well as forming, joining and coating processes. The backbone of a process chain is generally called “Synchroplan” where the main technical and business milestones for the different technologies and development processes are fixed. The challenges for the virtual planning process are response time and accuracy with respect to the Synchroplan milestones. In the early phase of product development it is helpful to make use of standards. These standards give guidelines for the product design process with respect to feasibility and robustness without restricting “engineering freedom” which will enable new styling and technical innovations. These standards are sometimes much more than just single numbers. For repeatable geometry details (door entrance, rear lights etc.) one can define so called meta models if these details can be represented by few parameters. The benefit of these meta models is the quick assessment of parameter combinations with an adequate accuracy. With this argumentation it is clear that an effective and efficient virtual engineering and planning process consists of three major components: - standards for geometry and process technology - fast CAD tool for creation of geometry proposals - effective CAE tool for fast and accurate assessment enabling definition of improvements The more standards are defined and accepted over the whole process chain the less detailed simulations and CAD loops are necessary. Nevertheless realisation of new styling ideas and technological improvements (new materials, improved crash worthiness etc.) always require CAD and CAE support. The backbone of the CAD process at BMW Group is currently the CAD system CATIA V5. All geometry information in the process chain has to be finally delivered in native CATIA V5 data. But especially in the early or so called concept phase of a project it is not necessary for sub processes that all CAD work is done in the backbone system. A typical example is the concept die face for the geometry definition of a forming simulation. With this geometry no physical tool is built and therefore no native CAD data is required. It is more important to realise the ideas and proposals of the engineer as fast as possible with a sufficient accuracy for FE-simulation. Nevertheless the geometric proposals after the engineering loop should be finally available in the CAD system. For the definition of a concept die face several working steps are (typically) necessary: - import of part geometry (ideally with native CAD data) - flange unfolding and lay out of geometry details from following operations - definition of the basic production idea (double part, symmetry, ...) - definition of drawing direction - part preparation (filling of holes, smoothening of boundary, ....) - creation of blank holder - design of addendum - preparation for simulation All these working steps beside the preparation for simulation can obviously be realised also in the standard CAD system. The most time consuming work is the creation of the addendum in comparison to specialised alternative solutions. This is the main reason why currently the concept die faces are not generally designed in CATIA V5. The accuracy and necessary design work for concept die faces strongly depends on the examination objectives. Especially the prediction of surface quality of outer skin panels necessitates much engineering work for the blank holder. Therewith the first contact of the blank with the forming tools is determined which causes sometimes unacceptable skid or impact lines. For the FE-simulation of concept die faces a powerful CAE tool is necessary. Beside of short calculation times an easy applicability is of high interest. Nevertheless one has need for well described complex material models and powerful user interfaces to solve extraordinary boundary value problems, e.g. for the virtual assessment of new forming technologies. LS-DYNA fulfils most of these demands and has a high application rate in research work at universities. In the past, the main objectives of forming simulations were only the assessment of feasibility (e.g. occurrence of necking and wrinkles). Nowadays additional and more complex examinations are possible due to improvements of the simulation systems. Some examples are press force calculation, multi stage forming, spring-back, surface quality, failure prediction for complex strain paths. Many of these applications need an accurate stress calculation. For new material grades like ultra high strength dual phase steels the classical material description is not sufficient anymore. The advantage in competition for automotive companies is the controllability in the virtual planning and engineering process even without having experience of series production. The more accurate the material description in the simulation tools the less problems and scrap rate occur in the production. Normally the first simulation of a concept die face will not lead to a feasible part geometry. In an effective virtual engineering and planning process it is necessary to show the way to feasible and robust production processes. The fast translation of simulation results in geometric proposals is an essential step. The handling of geometry updates is a big challenge for the work with concept die faces. An easy and robust parametric design of the concept die faces is still one of the biggest problems in this context. Even for specialised systems for the creation of concept die faces there is still much room for improvements. Due to this problem we should not restrict ourselves to single software systems from the general viewpoint of BMW Group. It is necessary to define useful interfaces and data formats. Therewith a fruitful competition and a market also for smaller software companies or university spin offs can exist. An example for such an interface is the description of a forming process based on a concept die face. It is necessary to define links on the tool geometry and sheet material, the forming direction and additional information like cam positions and directions. Tool meshes and detailed material data should not be included in this interface. The big advantage of intelligent interfaces is the possibility to combine different CAD and CAE systems as well as the possibility for fast modification loops. We expect a higher innovation velocity with widely accepted interfaces due to a wider market and more competitors. No publisher admin 2009-05-28T16:09:08Z File http://www.dynalook.com/european-conf-2009/A-I-06.pdf The traditional new-vehicle design cycle is very time consuming due to the sequential approach used. The need to reduce time to market for new vehicles as well as the increased affordability of high- performance computing, which can process hundreds of simulations concurrently, has led to the increased adoption of MDO processes. The goal of an MDO is to provide a more consistent, formalized process for complex system design than that found in traditional approaches, as well as to impact the design cycle through timely, performance-based direction. In essence, MDO aids in the management of the design process workflow itself. The MDO principle allows engineers and analysts to address multiple vehicle attributes such as safety performance, refinement and failure modes e.g. full frontal, offset, side and rear impacts, occupant restraints and total vehicle level NVH. This paper provides a formal and structured approach in the use of MDO at JaguarLandover to address complex and often conflicting requirements; arriving at better quality designs in a faster and more cost- effective manner. The use of MDO solutions increases the efficiency of the simulation processes by the following: Automation of many manual simulation processes to save time. Linking multiple simulation such as Crash, NVH and restrain to perform trade-off analyses Minimizing vehicle weight and meeting all vehicles attribute requirements. Find optimal designs and develop better products No publisher admin 2009-05-28T16:09:14Z File http://www.dynalook.com/european-conf-2009/A-II-02.pdf Long precision tubes are commonly made using the floating plug tube drawing process. The process has been analyzed using various methods e.g. upper bound method and FEM [1-10]. The die land and the plug land are usually cylindrical and form a cylindrical bearing channel between the die land and the plug land. The influence from the length of the bearing channel on the drawing force has only been dealt with in very few papers. In [2] it is recommended to use the shortest possible bearing channel in order to reduce the drawing force. A short bearing channel is also recommended in [6] both in order to reduce the drawing force, but also in order to increase the stability of the drawing process. The authors have not found any papers dealing with which influence the shape of the bearing channel has. The paper describes an analysis of tube drawing with a floating plug carried out using LS-DYNA®. The analysis shows that the drawing force, with conventional tooling, is heavily influenced both by the length and the shape of the bearing channel. The analysis has given inspiration to a new plug design, where the cylindrical plug land is replaced with a circular profiled plug land. Simulations of tube drawing with the new plug design show that the drawing force can be decreased and that the drawing force is nearly independent of the length of the die land and of small variations in the die land angle. With a conventional plug it is necessary at start up to make a dent in the tube behind the plug in order to force the plug into the right position in relation to the die. Without a dent the plug will be pushed ahead of the die and no reduction of the tube wall thickness will take place between the plug land and the die land. The dent is commonly made manually with a hammer and making the dent is difficult. If the dent is not made big enough the plug may pass the dent without being brought in the right position in relation to the die and if the dent is made too large this may lead to tube fracture. To ease the threading process at start up it is suggested to make the plug with a conical front end. By doing so the plug becomes self-catching; that is the frictional forces between the conical front end and the inside tube wall will set the plug in the right position in relation to the die during start up. Simulations show that the “self-catching plug” principle works. No publisher admin 2009-05-28T16:09:10Z File http://www.dynalook.com/european-conf-2009/A-II-04.pdf Deformation processes of structures under dynamic loading have been investigated both experimentally and by simulation for many years now. Various rate dependencies in many materials, wave and shock wave phenomena as well as material tests for their quantitative description have been identified. In parallel, mathematical formulations for the observed material behavior and numerical schemes for time dependent approximations of the governing partial differential equations have been developed. Since both the experimental characterization and the numerical simulation demand for assumptions, e.g. the state and distribution of stress and strain in a specimen or in a discretizing unit, increasing complexity of materials demands for advanced test set-ups and numerical methodologies. In this paper, a brief discrimination between the regimes of quasi-static, low-dynamic and high-dynamic loading conditions is given. Related experimental means for material characterization as well as components in the numerical model needed to represent the relevant physical aspects are given by some example cases. Specific emphasis is placed on the characterization of low-impedance materials and on the implementation of a micro-continuum based fabric model into LS-DYNA. An application of the resulting fabric model to ballistic simulations is shown in the final part. No publisher admin 2009-05-28T16:09:05Z File http://www.dynalook.com/european-conf-2009/A-II-05.pdf This study expounds the multi-objective optimization of a realistic crashworthiness problem with special reference to the incorporation of uncertainty and the visualization of the Pareto Optimal Frontier (POF). LS-OPT® and LS-DYNA® are used for the optimization based on the C2500 truck model developed by NHTSA. The design problem is set up as a Reliability-Based Design Optimization (RBDO) problem which includes specifications for the variation of the input parameters. For the purpose of design, reliability-based constraints on the displacements and stage pulses (interval-based integrals over the acceleration history) are specified. Nine thickness variables were assigned to various parts affecting the crashworthiness performance. Solution of the example employs Radial Basis Function networks as surrogate functions with Space Filling sampling as well as the NSGA-II algorithm for determining the POF starting from an infeasible design. Post-processing is done to determine a subset of optimal points of interest using the Viewer of LS-OPT® Version 4. This post- processor is based on a new architecture which allows window splitting and detachable windows for flexible viewing. It also includes the following new features: (1) Correlation Matrix, (2) Parallel Coordinate plot (POF) and (3) Hyper-Radial Visualization (POF). Thus 3 types of POF viewing are available, including the current 3D scatter plot. The study shows that a complex decision-making process such as optimal design involving uncertainty and multiple objectives can be simplified by using appropriate analysis and visualization tools. No publisher admin 2009-05-28T16:09:11Z File http://www.dynalook.com/european-conf-2009/A-II-06.pdf The introduction of the new LS-PrePost 3.0 will be presented here. A completely redesigned graphical user interface has been implemented in the new version of LS-PrePost 3.0. Tool bars and icons are being used for the main manual system to replace the old text based button system. The icons can be set to have text or without text. The new interface provides the maximum possible graphical area for the model rendering at the same time allow users to define their own toolbar with frequently used icons put together as they like. Besides using icons from the toolbars, a pull down manual system can also be used to reach to the function interfaces. Popup windows are used for each functional operation. Only one functional operational will be active at one time. Users can easily switch between the old and new interfaces if they do not feel comfortable in using the new interface. Also, an old to new interface button system has been implemented to transition users from the old interface to the new interface. Another major feature in LS-PrePost 3.0 is the newly developed geometry processing engine. The geometry processing engine is based on Open Cascade Technology 6.3. LS-PrePost 3.0 supports basic geometry entities such as lines, surfaces, and solids. It supports shape fixing and reshaping, such as fixing hole, small edge removal, vertex reposition and deletion, small face removal or face extension. It also supports faces stitching to provide better meshing result in the auto mesher. Geometry data can be imported via Iges or Step file format, while modified geometry also can be exported in iges file format. Surfaces can also be created from existing mesh using LSTC’s own reverse engineering module. Beside the new interface and geometry processing engine. New applications have been added to the LS-PrePost3.0 such as the Roller Hemming job setup and the LS-DYNA ALE job setup. An application frame work has been created such that new applications can be easily added in the future. No publisher admin 2009-06-25T15:10:49Z File http://www.dynalook.com/european-conf-2009/B-I-02.pdf Formula 1 motorsport is a platform for maximum race car driving performance resulting from high-tech developments in the area of lightweight materials and aerodynamic design. In order to ensure the driver’s safety in case of high-speed crashes, special impact structures are designed to absorb the race car’s kinetic energy and limit the decelerations acting on the human body. These energy absorbing structures are made of laminated composite sandwich materials - like the whole monocoque chassis - and have to meet defined crash test requirements specified by the FIA. This study covers the crash behaviour of the nose cone as the F1 racing car front impact structure. Finite element models for dynamic simulations with the explicit solver LS-DYNA are developed with the emphasis on the composite material modelling. Numerical results are compared to crash test data in terms of deceleration levels, absorbed energy and crushing mechanisms. The validation led to satisfying results and the overall conclusion that dynamic simulations with LS-DYNA can be a helpful tool in the design phase of an F1 racing car front impact structure. No publisher admin 2009-05-28T16:09:09Z File http://www.dynalook.com/european-conf-2009/B-I-03.pdf A growing number of safety systems are implemented in modern vehicles. Thereby vehicles become more complex and in succession the quantity of potential error causes is increasing. Numerical simulation and prototype tests are used to investigate vehicle behaviour and prevent aberrations at an early stage. However, prototype tests on full vehicle level are not feasible in early development stages. Numerical simulation is an effective tool reducing development time and costs, but hardware tests are still necessary to verify the simulation results. To handle these challenges in the development process new developing methods are necessary. In this paper an interface, which provides the implementation of control systems into finite element solvers is presented. This interface allows a more realistic behavior of these systems in numerical simulation. Thereby it is a useful tool, to design and adjust mechatronic systems, like integrated safety systems, at an early stage of the development process. This coupling method can also be used to check actuator configurations in substituted mechanical systems. Needed forces and accelerations are known before experimental testing, but disturbance variables cannot be pre-calculated. Therefore this method offers a possibility to verify, if the range of capacity of the actuator, the frequency and efficiency of the control algorithm are able to handle the prescribed behaviour. In order to consider the behavior of all systems in a close to realistic manner, associated control units must be built into the finite element model. This will be a prerequisite for the realization of an optimized mechatronic system configuration in future vehicles. No publisher admin 2009-05-28T16:09:12Z File http://www.dynalook.com/european-conf-2009/B-II-02.pdf In general, main assembly consists of different sub-assemblies. These sub-assemblies are joined together using rivets/bolts, welds etc. Individual subassembly is often verified for performance using commercial CAE software. To save time, rivet/bolt joints are usually modeled with beam-spider arrangement. Spider represents the rivet/bolt head and a beam connecting two spiders at the centre represents the rivet/bolt diameter. Analyst’s always try to perfect the verification close to practical conditions. In this article, the belt anchorage bracket in seat track assembly is considered for simulation. The performance of rivets joining the belt anchorage bracket to the upper rail of the track is studied in detail. In first simulation, these rivets are modeled with solid hexahedral elements. In the second simulation, these rivets are modeled with beam-spider arrangement. Stresses around the holes, in sheet metal belt anchorage bracket, are studied in both simulations. It has been found, that solid rivet proved to be better option over the beam-spider arrangement. The simulation is carried out as quasi static analysis in Ls-Dyna 971. No publisher admin 2009-05-28T16:09:13Z File http://www.dynalook.com/european-conf-2009/B-II-03.pdf The failure mechanism of common aeronautical structures is influenced by the crash behaviour of the riveted joints. Therefore, crashworthiness analyses of aeronautical structures require accurate models of the joints under crash conditions for a correct prediction of the crash behaviour of the structure. In this work, a method to create reliable FE models able to reproduce the behaviour of rivets under crash conditions is introduced. Using explicit FE codes, it is common practice to model rivets and bolts with rigid links or beams, and adopt as a failure criterion the allowable forces envelope obtained for a single rivet after tests [1]. It is shown here that numerical simulations of tests carried out on a single rivet under different loading conditions can be used to characterise the crash behaviour of riveted joints in place of expensive and time-consuming test campaigns. A specific test device was built in order to apply multi-axial loads to a single rivet and perform tests to evaluate the behaviour of a rivet under different loading conditions: from pure shear to pure tension. Numerical simulations of the single rivet test were then carried out using LS-Dyna [1] to reproduce experimental test and to validate the numerical model of the rivet. The rivet was discretised with solid eight-node elements and the piecewise linear plasticity material model was initially used. However, different constitutive laws were then used to characterise areas with either compressive or tensile loads. The whole loading process, from bucking to failure was simulated. Numerical results and test data were compared and it was observed that the numerical models are able to correctly represent the behaviour of a rivet after a tuning of the material parameters and therefore can be used to characterise a riveted joint. At this stage of the research, only quasi-static loading conditions were considered. This assumption allowed reducing the number of parameters that affects the calculations thus simplifying the model set-up. Future works will investigate the effect of strain rate to reproduce crash conditions. No publisher admin 2009-05-28T16:11:30Z File http://www.dynalook.com/european-conf-2009/B-II-04.pdf The analysis of adhesive bonded joints and structures relies on accurate materials data and mathematical models. In the present study the goal was to develop a method for simulating accurately, using LS-Dyna, the behaviour of aluminium structures bonded with a single part, heat curing epoxy adhesive. This required a structure with known boundary conditions and for which the substrates deformed in a predictable manner. A suitable specimen, formed from two folded aluminium tubes bonded into a T-shape, had been developed by Ford Research Center, Aachen. The MAT 169 material card was selected as a method that showed promise for use in the simulation of bonded joints. A test programme was developed to characterise the adhesive for use with the MAT 169 material card, using tests from the British Standards catalogue. These data were then used to analyse the T-shaped structure under quasi static loading. The results of tests and analysis of the T-shaped structures were used to assess the accuracy of the adhesive characterisation and suitability of the MAT 169 material card. A parametric study was then carried out to determine the robustness of the solutions. Once it had been established that a robust solution had been reached the results from the parametric study were used to develop an optimised set of input data for the adhesive. No publisher admin 2009-05-28T16:11:30Z File http://www.dynalook.com/european-conf-2009/B-III-01.pdf To improve the accuracy of crashworthiness simulation, it is preferable to consider the effects of metal forming. However, this approach was difficult in practice since analyzing the stamping simulation in detail requires much work. This paper describes the influence of residual strain, work hardening and material thickness changes resulting from the stamping process on the crashworthiness simulation. In almost all impact load cases, the results show that deformation is reduced by the work hardening effects. These results are verified by actual experimental data. No publisher admin 2009-05-28T16:11:25Z File http://www.dynalook.com/european-conf-2009/B-III-02.pdf Crashworthiness simulations using explicit Finite Element methods are a central part of the CAE process chain of car body development. Since crash tests of prototype cars at an early development stage are very expensive, a maximum in predictive performance of crash simulations can make a substantial contribution to a cost-efficient car development process. A central issue to ensure this, is an accurate prediction of crack formation in crashworthiness simulations. As the use of advanced high-strength materials in modern car body structures is increasing, crack formation is more likely to occur in such parts of the body-in-white. Typically, structural parts of a car body are manufactured by means of deep-drawing processes. Due to this, the local properties of these parts can be changed remarkably compared to the unprocessed material. In order to be able to accurately predict crack formation, the damage history including local plastic strain and pre-damage has to be considered. Since the use of forming simulations has become usual practice for sheet metal manufacturing, a damage model suitable to be used for both forming and crashworthiness simulations will be presented in the following. Based on the well-known failure criterion of Johnson and Cook, a generalized formulation is proposed that can account for complex failure modes in modern high strength materials. Numerical examples will be presented to demonstrate the practical use of the damage model for the process chain of sheet metal manufacturing. No publisher admin 2009-05-28T16:11:22Z File