Modeling of ductile behavior of metals under a wide range of loading rates : semi-empirical approach
Résumé
It is well-known that impact problems and high rate metal forming processes induce sever loading conditions; therefore, it is necessary to develop robust tools to predict structural response of metals for these applications. In this paper, we propose a semi-empirical elastic-viscoplastic-damage constitutive behaviour for ductile metals. Our description of the plastic deformation behaviour takes into account the physical aspects via a mechanical threshold stress and an Arrhenius type expression relating strain rate to activation energy and temperature. Like in the mechanical threshold stress model, the flow stress is decomposed as the sum of an effective stress and a thermally-activated component. Non-linear isotropic damage evolution law is based on the theory of continuum damage mechanics by assuming the existence of new ductile damage dissipation potential. The models are implemented via a user material subroutine (VUMAT) in the commercial finite element code ABAQUS/Explicit. We performed numerical simulation for high speed blanking process of thin copper sheets and uni-axial loading tests. The numerical results based on our constitutive law are in a good agreement with the experimental results for the stress-train response, damage evolution and the blanking profil