Quantitative prediction and ranking of the shock sensitivity of explosives via reactive molecular dynamics simulations

Abstract

A deep understanding of explosive sensitivities and their factors is important for safe and reliable applications. However, quantitative prediction of the sensitivities is difficult. Here, reactive molecular dynamics simulation models for high-speed piston impacts on explosive supercells were established. Simulations were also performed to investigate shock-induced reactions of various high-energy explosives. The fraction of reacted explosive molecules in an initial supercell changed linearly with the propagation distance of the shock-wave front. The corresponding slope could be used as a reaction rate for a specific shock-loading velocity. Reaction rates that varied with the shock-loading pressure exhibited two-stage linearities with different slopes. The two inflection points corresponded to the initial and accelerated reactions, which respectively correlated to the thresholds of shock-induced ignition and detonation. Therefore, the ignition and detonation critical pressures could be determined. The sensitivity could then be a quantitative prediction of the critical pressure. The accuracies of the quantitative shock sensitivity predictions were verified by comparing the impact and shock sensitivities of common explosives and the characteristics of anisotropic shock-induced reactions. Molecular dynamics simulations quantitatively predict and rank shock sensitivities by using only crystal structures of the explosives. Overall, this method will enable the design and safe use of explosives.