Mesoscale modeling of the Shock-to-Detonation Transition of pressed-HMX based on a surface regression model

Shock-to-Detonation Transition (SDT) of heterogeneous high explosives results from processes occurring at the microstructural level. Thus, mesoscale modeling is expected to allow a better comprehension of the SDT. Recent experimental evidence suggested that hotspots mainly developed on the surface of the energetic crystals, which are then consumed by the propagation of a deflagration front. In the present study, mesoscale simulations of the SDT of pressed HMX were performed. The reactive model employed consisted of igniting the surface of the crystals after the shock passage, and reconstructing the burn front propagation, using a modified Youngs' method. In this reactive model, the velocity of the deflagration front was modeled by a pressure-dependent law, as suggested by the literature. The simulations showed that the Single Curve Initiation principle remained valid. The parameter deflagration velocity times the surface to volume ratio was found to enable the equivalence between microstructures. This approach provides a new framework to study the SDT of heterogeneous explosives, by considering how the combustion of energetic crystals participate to the shock acceleration and transition into a detonation. This paper serves as a proof of concept, applied to the pressed HMX. image