A Comparison of recent Damage and Failure Models for Steel Materials in Crashworthiness Application in LS-DYNA

With increasing requirements on crashworthiness, and light-weight car body structures being a central issue in the future of automotive development, the use of high strength steel grades has become wide-spread in modern vehicles. Since these materials all too often show significantly lower ductility than conventional steels, it is of great importance to precisely predict their failure in crash loading conditions. Hence constitutive models in crashworthiness applications need to be able to correctly predict damage and failure mechanisms. These aforementioned, enhanced models are regularly based on a larger number of variables that define the loading history based on stress or strain measures and on accumulated plastic strain and damage variables more or less accurate. Moreover, these models may require initialization with locally computed history properties prior to a crashworthiness simulation in order to predict the subsequent loading response correctly. Furthermore it should be mentioned that orthotropic properties of steel sheets play a major role in the forming process. Hence one may expect that orthotropic behaviour in damage accumulation may also be a major mechanism when failure prediction along the forming-to-crash process chain is evaluated. It is therefore of great importance to not only evaluate the many available models in LS-DYNA based on their performance achieved in crash loading scenarios but also take the production step with mapping of history data into account. The present paper will focus on the different models available in LS-DYNA, e.g. Gurson, Johnson-Cook, GISSMO etc. and discuss the advantages and disadvantages in application, calibration and predictive performance in the light of the producibility-to-servicability simulation chain.