Void collapse in shocked β-HMX single crystals across scales*

Heat generation in the vicinity of a void during shock compression plays a critical role on the initiation of detonation in high explosives (HE). Atomistic simulations of under shock compression have shown that the void collapse regime transitions from visco-plastic to hydrodynamic jetting as the shock strength increases in many energetic materials. However, atomistic simulations are limited to nanometer size voids. On the other hand, void collapse experiments have been performed in micron size samples. Here, we present a mesoscale model informed from atomistic simulations to study the anisotropic response of shocked β-HMX single crystals that bridges nanometer to micrometer scales. The shock response of an β-HMX single crystal containing a void is studied with finite element simulations that include plasticity and heat transport. The effect of crystal orientation over a range of impact velocities are discussed. The continuum model is calibrated with non-reactive molecular dynamics simulations of planar socks. The simulations are compared with both atomistic simulations and gas gun experimental results of β-HMX containing a single void.