Thermodynamically consistent and microstructure informed porosity-based dynamic ductile damage model

A thermodynamically consistent finite deformation macroscale damage model for the nucleation and growth of voids under dynamic loading conditions is presented. Voids are modelled as thick-walled spheres within a representative volume element (RVE). Thick-walled spheres are distributed according to a physically informed probability distribution function which serves as integration weight for formation of the volume averaged macroscale porosity from the distributed microscale porosity. An isotropic finite deformation thermomechanical dislocation-based macroscale plasticity model is extended to include the energetic cost of free surface creation. The effects of inertia, compressibility, and creation of free surfaces are included for the high triaxiality shock conditions. The complete damage model is used to describe three different plate impact experiments conducted with high-purity tantalum. These three experiments differ in their impact velocity and imposed stress profile via graded flyer plate design and result in significantly different damage fields and free-surface velocity traces. The results are interpreted in the context of energy partitioning and numerical simulations are compared directly with the experimental damage fields and free-surface velocity profiles.