Exploring Shock-to-Detonation Transitions in Pressed HMX: A Mesoscale Approach Using Surface Regression

The Shock-to-Detonation Transition (SDT) of heterogeneous explosives results from processes occurring at the microstructural level. Therefore, mesoscale modeling is expected to enhance the understanding of the SDT. Recent experimental findings have suggested that hotspots primarily form on the surface of energetic crystals, which are subsequently consumed by the propagation of a deflagration front. In this study, mesoscale simulations of the SDT of pressed HMX were conducted. The reactive model used involved igniting the crystal surfaces after the passage of the shock and reconstructing the propagation of the burning front using a modified Youngs’ method. In this model, the deflagration front velocity was described by a pressure-dependent law, as proposed in the literature. The simulations demonstrated that the Single Curve Initiation principle remained valid. The product of the deflagration velocity and the surface-to-volume ratio was found to enable an equivalence between microstructures. This approach provides a new framework for studying the SDT of heterogeneous explosives by considering how the combustion of energetic crystals contributes to the acceleration of the shock and to the transition to detonation.