Temperature evolution in plastic bonded explosives during impacts

The heterogeneous, polycrystalline structure of plastic-bonded explosives (PBX) leads to temperature localization under impacts. The thermo-mechanical responses of PBXs span processes from dislocation-mediated plasticity at small-scales to interfacial stress wave reflection and diffusion at higher scales. The thermal and deformation localization response under impact of a RDX/estane PBX have been studied using finite element simulations with ABAQUS. The modeling framework combines a dislocation-based, anisotropic, single crystal plasticity model with a visco-elastic constitutive model for estane. We systematically studied how heating arising from wave interactions and localized plasticity in the PBX depends on the impact velocity, slip resistance, grain orientation, position, and proximity to stress concentrators. The broadening of the shock front with increasing run distance by the microstructure of the PBX was found to play an important role in the evolution of temperature in the PBX. Grains with certain orientations produced higher temperatures and larger localized zones. Higher intrinsic resistance to slip restricts the dislocation density growth and thermal localization.