High-speed blanking of copper alloy sheets : material modeling at high rates of strain and numerical prediction of the effects of processing parameters

For a large number of metal forming processes and impact applications, the loading conditions are so severe. Therefore, it is necessary to develop robust tools to predict structural response of metals under these loading conditions. In this paper, we propose a semi-empirical elastic-viscoplastic material model combined with a non-linear isotropic damage evolution law. The effect of strain hardening, strain-rate hardening, pressure and thermal softening have been incorporated in the response of material for a wide range of loading rates. Like in the mechanical threshold stress model, the flow stress is decomposed as the sum of an effective stress and a thermally-activated component. The proposed model is a semi-empirical description of the plastic deformation behaviour of ductile metals where some of the physical aspects are taken into account via the mechanical threshold stress and an Arrhenius type expression relating strain rate to activation energy and temperature. The damage evolution law is based on the theory of continuum damage mechanics by assuming the existence of new ductile damage dissipation potential.