The effect of crystal orientation on shock loading of single crystal energetic materials

Void collapse under shock loading has become a model problem to study the nucleation of hot spots in high energy density materials. While experimental observation of this phenomenon remains elusive, simulations can help identify the relevant physical mechanisms for heat generation and criticality. A finite element method approach to simulate shock waves that includes crystal plasticity, with a power-law slip rate, hardening law and an equation of state is presented. Numerical simulations of shock loading of single crystal beta-HMX containing a cylindrical hole of diameter 10 mu m are performed with different orientations and impact velocities in 3D and under plane strain conditions. The elastoplastic response, including the temperature increase due to plastic dissipation, is strongly affected by the crystal orientation. Specifically, the ((1) over bar (1) over bar 1)-oriented crystal shows the highest temperature increase. These results can guide the design of experiments to investigate processes at the micrometer length scales in energetic materials.