A Statistical Hot Spot Reaction Rate Model for Shock Initiation of Polymer-Bonded Explosives

A statistical hot spot reaction rate model for shock initiation and detonation of heterogeneous solid explosives is developed to devote a physically realistic description of the formation, growth, or coalescence of hot spots, combustion, and rapid transition to detonation. One of the most significant advantages of the statistical model is that it predicts well the influence of mesoscopic void size distribution and critical size of activated hot spots on the shock initiation and detonation growth of PBXs. The calculated pressure histories in both TATB-based LX-17 and HMX-based PBX9501 are found to be in good agreement with the experimental data. It is found that the shock initiation behavior of the HMX-based PBX is mainly controlled by the number density of hot spots and shows an accelerated reaction characteristic and that of the TATB-based PBX is determined by the combustion reaction process, which featured by a stable reaction characteristic. It is also found that the void size inside the explosive should be restricted as small as possible to effectively reduce the initiation sensitivity. The results could advance our knowledge of shock initiation of PBXs and provide guidelines for the synthesis of insensitive high composite explosives.