Berücksichtigung von Blechumformergebnissen in der Crashberechnung

So far in the numeric simulation of strength-, durability-, NVH- and crash-problems the process history of sheet metals, e. g. hardening of the material and thinning of the sheet due to the forming process, is not taken into account on a regular basis. For many structurally relevant parts a forming-simulation to study producibility and accuracy, based on various algorithmic techniques, is conducted though. Hence for a great number of these parts the necessary simulation data is at hands already. The main objective of the present contribution is the crashworthiness simulation. Thus in order to further increase and improve the prediction capabilities of existing models in crash-simulation, the results of these forming-simulations need to be transferred into the crash models. In this respect the present contribution focuses on two key questions: Which are the history variables (geometrically and materially) that can be meaningfully mapped to crash-models in present automotive applications and how can the integration of the methodology into the product development process be smoothly accomplished. While the answer to the first question is strongly dependent on the applied constitutive model in both, the forming and the crash-simulation, the second one needs to be discussed with respect to the available simulation environment. Special attention is therefore put on the advantages and drawbacks of different possible procedures - which are available at present - to map history variables (in particular sheet thickness and plastic strains) from the finer forming-mesh to a relatively coarse crash-discretization. The expenditure for data preparation and data storage needed as well as the quality of results obtained with the different procedures are evaluated comparatively with respect to the cost effectiveness of the process chain. Gaining more exact predictions of displacements, stresses and strains in the analysis and the possibility to save weight through a better optimized structure are the key factors that drives the present development.

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