低速撞击下PBX炸药黏弹塑性细观损伤点火模型研究

Viscoelastic Plastic Meso-Damage Ignition Model Study of Polymer Bonded Explosive Under Low Velocity Impact

为研究塑性黏结炸药PBX-9501在低速撞击条件下的力学变形、损伤以及温升情况,发展了基于黏塑性演化方程以及复杂应力状态下微裂纹形核、演化机制的非线性黏弹塑性细观损伤力热化学耦合模型.通过分析低速撞击试验中力学变形-损伤对炸药宏细观温升的影响,可确定炸药发生点火的主导机制及点火速度阈值,结果表明:撞击速度为59 m/s时PBX-9501炸药呈现大变形与破碎响应特征,顶部位置微裂纹和微孔洞演化程度最高,裂纹摩擦热点机制对炸药热点温升起主要作用;随着撞击速度增大,微裂纹热点机制仍为点火主导机制,可预测得到PBX-9501炸药点火临界撞击速度为120~125 m/s.

To investigate the mechanical deformation,damage and thermal response of polymer bonded explos-ive PBX-9501 under low velocity impact,a nonlinear viscoelastic plastic meso-damage mechano-chemical coup-ling model based on viscoplasticity evolution equation and micro-crack nucleation and evolution mechanism un-der complex stress state was developed.By analyzing the influence of mechanical deformation and damage on the macro and micro temperature increase of explosive in the low velocity impact test,the dominant ignition mechanism and ignition velocity threshold of explosive were determined.It is found that PBX-9501 explosive exhibits large deformation and crushing response at an impact velocity of 59 m/s.The damage degree induced by microcracks and microvoids are the highest at the top,and the micro-crack mechanism plays an important role in the temperature increase of hot spot;with the increase of impact velocity,the microcrack mechanism is still the dominant ignition mechanism and the critical velocity of ignition of PBX-9501 is predicted to be 120~125 m/s.