Head-to-Head Comparison of Molecular and Continuum Simulations of Shock-Induced Pore Collapse in β-Octahydro-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine (β-HMX)

Shock-induced pore collapse in the energetic molecular crystal β-HMX is examined using all-atom molecular dynamics (MD, LAMMPS) and continuum mechanics (SCIMITAR3D) for nearly identical simulation domains under the same impact conditions. Treating MD predictions as ‘ground truth’, a hierarchy of increasingly MD-informed continuum material models was systematically ‘upgraded’ with temperature- and pressure-dependent MD-derived material parameters. Starting with a simple isotropic, elastic-perfectly plastic material model, the model is improved stepwise by adding strain-, strain-rate-, and temperature-dependent isotropic plasticity (Johnson-Cook J2), pressure-dependent melting temperature from MD, and pressure-dependent mechanical properties from MD. Continuum predictions of shear-band patterns, pore-collapse profile and mechanisms, and hotspot formation during collapse of circular and elongated pores using the MD-guided material model are in overall good agreement with MD results.