A micromechanical constitutive model for dynamic damage and fracture of ductile materials

摘要

This paper proposes a detailed theoreticalanalysis of the development of dynamic damage inplate impact experiments for the case of high-puritytantalum. Our micro-mechanical model of damage isbased on physical mechanisms (void nucleation andgrowth). The model is aimed to be general enough tobe applied to a variety of ductile materials subjected tohigh tensile pressure loading. In this respect, the workof Czarnota et al. (J Mech Phys Solids 56:1624-1650,2008) has been extended by introducing the conceptof nucleation law and by entering a nonlinear formula-tion of the elastic response based on the Mie-Gruneisen equation of state. This later aspect allows us to con-sider high impact velocities. All model parameters aredirectly assessed by experimental measurements to theexception of the nucleation law which is characterizedby the way of an inverse identification method usingthree free-surface velocity profiles (at low, intermedi-ate and high impact velocities). It is shown that thenucleation law can be consistently determined in therange of operating pressures. The nucleation law beingidentified, the development of internal damage happensto be a natural outcome of the modelling. The model isapplied to predict damage development and free-sur-face velocity profiles for various test conditions. Thevariety and the quality of results support the physicalbasis (in particular micro-inertia effects) upon whichthe proposed model of dynamic damage is based.