Influence of Dislocations on the Shock Sensitivity of RDX: Molecular Dynamics Simulations by Reactive Force Field

Molecular dynamics simulations of the chemical responses of shocked dislocation-contained and perfect (p) 1,3,5-trinitro-1,3,5-triazinane (RDX) crystals were performed using the ReaxFF force field combined with the multiscale shock technique. The shear dynamics of four types of dislocated RDX crystals are also modeled. The predicted mobilities of the crystals decrease in the order of (010) [001]/screw (s2) > (010) [001]/edge (e2) > (010) 1/2[100]/screw (s1) > (010)­1/2[100]/edge (e1) according to their shear stress barriers, thus revealing the initial driving force required to activate a slip system. In view of the evolution of temperatures, pressures, and reactant decay rates of the shocked perfect and dislocated RDX, we confirm that shock sensitivity follows the order of e2 > e1 > s1 ≈ s2 > p. In particular, all dislocations enhance the shock sensitivity of RDX; in particular, edge dislocations enhance shock sensitivity significantly, whereas screw dislocations enhance it slightly. Shock sensitivity is not proportional to the shear stress barrier, which implies other factors influence shock initiation besides shear