The shock to detonation transition in heterogeneous plastically bonded explosives is dominated by energy localization into hotspots that arise from the interaction of the shockwave with microstructural features and defects. The complex polycrystalline structure of these materials leads to a network of hotspot that can coalesce into deflagration and detonation waves. Significant progress has been made on the formation and potency of hotspots using atomistic simulations, but most of the work has focused on ideal and isolated defects. Hence, developed a method, denoted PBXGen, to build realistic PBX microstructures for all‐atom simulations. PBXGen is generally applicable, and we demonstrate it with two systems: an RDX‐polystyrene PBX with a 3D microstructure and a TATB‐polystyrene with columnar grains. The resulting structure exhibit key features of PBXs, albeit at smaller scales, and are validated against experimental mechanical and shock properties.

We use molecular dynamics simulations to characterize the shock-induced collapse of porosity of 1,3,5,7-tetranitro-1,3,5,7-tetrazoctane. We focus on how pore size and shape affect the collapse mechanism and resulting hotspot temperature distribution. Within the hydrodynamic collapse regime, for particle velocities above 0.7 km/s, we find that a combination of the curvature of the downstream surface and void length affects the terminal velocity of the expanding material and, consequently, temperature. Increasing curvature and length result in faster speeds, including jetting, and higher temperatures. For long and thin voids, there is a maximum in temperature with curvature as lateral collapse restricts the expanding material. The simulations map void size and shape to the resulting hotspot and provide a key piece of information toward the development of predictive modeling of shock-induced initiation.