Void collapse in shocked β-<u>HMX</u> single crystals across scales

Heat generation in the vicinity of a void during shock compression plays a critical role in the initiation of high explosives (HE). Atomistic simulations of β-HMX under shock compression have shown that the void collapse regime transitions from viscoplastic to hydrodynamic jetting as the shock strength increases. However, they are limited to very small length and time scales and are computationally costly. Then, a mesoscale model informed with atomistic simulations results is needed to study the anisotropic response of shocked single β-HMX crystals at larger scales, and to understand similarities\differences of the deformation response across scales. In this work, the shock response of a β-HMX single crystal containing a void is studied with finite element simulations that include plasticity and heat transport. The effects of crystal orientation and impact velocity on the deformation response of the single crystal are discussed. The model is calibrated with non-reactive molecular dynamics simulations. Results are compared with both atomistic simulations and gas gun experimental results of β-HMX containing a single void.