Effect of shock-induced plastic deformation on mesoscale criticality of 1,3,5-trinitro-1,3,5-triazinane (RDX)

BH Lee and JP Larentzos and JK Brennan and A Strachan, JOURNAL OF APPLIED PHYSICS, 134, 105901 (2023).

DOI: 10.1063/5.0163358

Shock-induced plasticity and structural changes in energetic molecular crystals are well documented. These processes couple with the leading shock wave and affect its propagation, resulting in long, transient responses that are challenging to capture with all-atom simulations due to their time scale. Hence, the effects of this coupling and the transient shock response on the formation of hotspots and the initiation of chemistry remain unclear. To address these challenges, we investigate the role of shock-induced plastic deformation on shock initiation with a recently developed particle-based, coarse-grain model for 1,3,5-trinitro-1,3,5-triazinane (RDX) that utilizes the generalized dissipative particle dynamics with reactions framework. This model enables reactive simulations at micron length scales, which are required to achieve steady-state shock propagation. The simulations show that the shock Hugoniot response of RDX can involve transient behavior for up to 150 ps before steady-state behavior is achieved for shock strengths above the elastic limit. Pore collapse simulations demonstrate that the intensity of the resulting hotspot will weaken as the shock transitions from transient to steady-state behavior, ultimately affecting the shock- to-deflagration transition. Our results highlight the importance of considering the mesoscopic effects of shock-induced plastic deformation in simulations of shock-to-deflagration transitions of high explosives.

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