Shock initiation of RDX, emerging behavior at micron-scale investigated with molecular reactive model

Shock initiation of high explosive (HE) is a multiscale phenomenon involving both physical and chemical processes. To investigate such process, simulation methods with resolutions ranging from atomistic, mesoscale, to continuum methods have been utilized. Recently, we have developed a reactive, particle-based model of RDX that coarse grain (CG) the entire RDX molecule as a CG bead. The model, under Generalized Dissipative Particle Dynamics with Reactions (GenDPDE-RX) framework, has demonstrated that it can capture the role of microstructure on shock response of RDX and can display accurate decomposition chemistry with respect to reactive atomistic simulations through extensive validation experiments while exhibiting several orders of magnitude improvement in computational efficiency compared to atomistic methods. Here, we utilize the model to investigate the shock-to-deflagration transition of RDX at μm scales. Our investigation demonstrates that many aspects of the shock response, such as its time-dependent behavior, are only observable at O(100 ps, μm). Overall, these results suggest additional factors that can advance development of predictive models for HE.