With the trend towards lightweight construction, advanced high-strength steel (AHSS) is increasingly being used in automotive structural components. Since the ductility of high strength steels is relatively low, damage behaviour of these materials must be accurately modelled. In automotive structures AHSS components are usually discretized with shell elements. With the increase of computation capacity attempts with solid elements are made to capture the loading state more accurately, especially after necking. For this reason, it is convenient to develop a method which enables a systematic model calibration from the 3D to the 2D loading situation. The failure strain of metallic materials depends on stress state. In the past years several studies have shown that the stress triaxiality is not sufficient to describe failure and empirical models were extended to consider the effect of Lode parameter. Recently it was also shown that the amount of bending seems to influence failure, namely i.e. the failure strain increases with the amount of bending.
GISSMO has become an incredibly flexible tool since its inception. An overview is not to be presented here owing to the fact it is coved extensively by other authors. This body of work aims to show that even using simple techniques and features a robust GISSMO card is possible using only *MAT_024 and *MAT_ADD_EROSION, that can be useful in automotive safety, even with larger type 16 shell elements 3-6mm in edge length for gauges approx. 1-2mm. 3-6mm quad elements are a very useful size for automotive structures and allows accurate meshing of holes, flanges and joints for example.
This paper describes an engineering process to generate material cards for forefront crashworthiness CAE analysis that properly capture both plastic and fracture behaviour of car body structural metals. The main objective of the paper is to show that advanced plasticity approaches can be used without significantly increasing the complexity of the overall material characterization process. The paper is mainly centred in metals plastic characterization for shell elements although some important relationships with the fracture characterization will be also discussed. Before defining the engineering process, it is necessary to tackle some misleading general ideas that the automotive CAE community normally assumes as correct for metals like steel or aluminium alloys.
In this research work, the effective Taylor-Quinney Coefficient (TQC) table of *MAT_224 for Aluminum 2024-T351 alloy was developed to replace the current constant TQC. The methodology to create the effective TQC table was developed by using a two-step approach. In Step 1, the thermal-structural analyses of tensile tests were conducted to verify the referenced TQC values and generate the additional temperature-strain curves at additional rates which were not covered by the physical tensile tests. In Step 2, the structural-only analyses of tensile tests were conducted to calibrate the effective TQC values at all the rates for the effective TQC table and validate the calibrated effective TQC table.
In this paper, a strategy for numerical simulation of cutting during concurrent pressing of stainless steel sheet metal is investigated while accounting for the stress triaxiality and Lode angle parameter. An inverse modelling approach is used, where both a material model and a damage model are calibrated. The damage model is developed using the GISSMO damage model (Generalized Incremental Stress State dependent damage Model).
Failure model calibration of a DP1000 dual phase steel using solid and shell elements for crash simulation