Constitutive relations for copper with two mechanisms including twinning for a use under shock wave loading

Abstract
A set of compression tests on an annealed copper was at first rather well fitted by an elasto-plastic model elaborated from the one proposed by Zerilli and Armstrong. Then, various shock loading tests were realized on the annealed material. Compression tests on recovered specimens allowed to characterize the post-shock properties, for shock pressures from 10.5 to 61.3 GPa. This post-shock behavior could not be found with a simple pre-strain added in the model built for the material in its initial state because the twinning is activated under shock and not during compression tests on the annealed material. In order to improve the simulation of shock loading phases, a model is proposed which includes two competing plastic deformation mechanisms: dislocations glide and twinning. At last, the effect of a slight pre-strain before a shock loading was experimentally and numerically studied.