高温下带金属壳PBX炸药低速撞击敏感性数值模拟

Accidental initiations of the explosive subjected to mechanical or thermal loads have caused numerous catastrophic tragedies. The impact sensitivity and thermal safety of explosive is of great importance for the applications. Previous work showed an evident decline on modulus with increasing cook-off temperature, which suggest that Cook-off temperature may affect the deformation process of the impacted PBX, and further affect the critical impact velocities for initiation. In this work, to investigate the mechanical and thermal response of confined PBX charge under low velocity impact of a small projectile during cook-off events, a finite-element model was established to provide reliable prediction of explosive safety performance at high temperature. A thermal-mechanical-combined experiments from literature enabled comparisons between simulated results and measured data for the critical impact velocities of initiation for a HMX-based PBX charge (HMX/TATB/olefin). The simulation results showed that when it was heated up to 348.15 K, the critical impact velocity of initiation for the explosives reached the maximum (360 m/s). With the increase of cook-off temperature, the localized heating regions change from the surface of explosive charge to the center. This phenomenon was caused by the effect of compression overshadows shearing on the initiation because of the strength decreases in the heated PBX, implying that thermal softening plays an important role in the impact sensitivity of the heated PBX charge.