Identification of an elasto-viscoplastic flow stress in large strains and large strain rates of a paint film from impacts

International audience ; To achieve computer simulations of forming processes using the finite element method (FEM), we need input data such as non linear material behaviour laws and friction laws. In the majority of cases these data are very specific to the studied process because they transfer the physical phenomena acting in the studied process. Thus there are no direct experimental means that can provide us these data. Inverse problems give us an answer to this lack of input data. This consists of evaluating the parameters that would lead to the most accurate model, minimizing the difference between the experimental and its simulation results. In this paper, we propose to identify the parameters of the material behaviour law in the case of impact loading of a polyurethane paint film (PAC33) by solving the corresponding inverse problem. This inverse problem consists of adjusting the paint's behaviour law parameters in the finite element model until the calculated crater dimensions match the measured dimensions in the least square sense.