损伤累积下PBX炸药低速撞击点火行为的数值模拟

To study the effect of the microcrack damage accumulation on ignition behavior of PBXs under low-velocity impact, the mechanical-thermal-chemical coupled model of PBXs considered the asymmetric evolution of microcrack under tension and compression, was used to simulate the ignition behavior of HMX-based PBXs with damage accumulation. The damage accumulation was generated by multiple impact. In addition, the ignition behavior of PBXs under multiple impacts of flat and pin projectiles was simulated. The calculation results showed that with damage accumulation, the ignition threshold of PBXs under the second impact nonlinearly decreased as the first impact velocity increased. It was becasue that multiple impacts increased the damage degree of cracks which propagated circumferentially in the impact area, and the accumulation of circumferential cracks strengthened the shear deformation of PBXs, which leaded to the generation of frictional heat between the surface of cracks, and hotspots formed. The damage degree of PBXs increased around the edge of the projectile under impacts of the flat projectile, and ignition occurred at the same position. Under multiple impacts of pin projectile, the crack damage significantly increased, which also leaded to the ignition of PBXs.