The ignition characteristics and the law of hot-spot formation on composite explosive subjected to drop weight impact were investigated by using the coupled thermo-mechanical method, selecting the thermo-elastic-plastic material model from nonlinear dynamics finite element software ANSYS/LS_DYNA,and simulating chemical exothermic reaction of explosive in the heat generation rate and considering the exothermic reaction of composite explosive itself. The finite element model used to simulate impact sensitivities was built by taking comp. B explosives as a caculation example. The results show that the numerical simulation method is feasible to simulate the transient heat release and the fast rise of temperature in composite explosive. The high temperature hot-spot in comp. B explosive is easily formed with the increment of up impact plunger velocity. When the velocity of up impact plunger is 5 m·s-1 , the hot-spot temperature enhances,and at 0.7 ms the hot-spots close to or above the critical temperature are formed,and ignition reaction occurs. The calculated results provide the theoretical foundations to judge the explosive impact ignition.%采用用热力耦合方法,选择有限元软件ANSYS/LS_DYNA中带热效应的弹性-粘塑性材料模型,考虑炸药自身的反应放热,以生热速率模拟炸药发生的化学放热反应,研究了混合炸药在落锤撞击下的点火特性和热点形成规律.以Comp.B炸药为算例,建立了撞击感度的有限元模型.结果表明,该数值模拟法模拟炸药瞬态放热和炸药内部产生的急剧温升是可行的.随着上击柱速度的增大,Comp.B炸药内部的高温热点越易形成.当上击柱速度为5m·s-1时热点温度增大,0.7 ms时形成接近或超过临界温度的热点并发生点火反应.计算结果为判断炸药撞击点火提供了理论依据.
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