缓慢加热条件下壳装PBX炸药响应特性研究

Study on response characteristics of insensitive PBX explosive in shell under slow cook-off

为了研究弹药在热刺激作用下的响应规律,进行了壳装PBX炸药慢速烤燃试验,获得了1 K/min升温速率下壳体内部的压力-时间曲线,壳体内部压力变化过程表现为炸药热分解产气段、点火燃烧段和壳体破裂段3个阶段。提出了一种模拟计算慢速烤燃时壳装PBX炸药发生低等级响应过程的理论方法,首先计算炸药点火前的温度场分布,引入热分解系数k描述炸药热分解消耗的程度,在此基础上建立改进的内弹道方程组,模拟计算了因炸药点火燃烧导致壳体内部压力快速上升的行为,理论值和试验值吻合良好,随后应用LS-DYNA软件模拟了壳体在内部压力作用下的破裂行为。计算了1.0~10.0 K/min之间6种不同升温速率条件下炸药点火后的压力-时间曲线,当升温速率为1.0 K/min时,炸药点火后压力增长速率明显高于其他工况。

To study the response law of ammunition under thermal stimulation,a slow cook-off test of PBX explosive in a shell was carried out and the heating rate was 1 K/min.The pressure-time curve inside the shell was obtained.The pressure change process inside the shell is divided into three sections:a section in which the pressure increases slowly due to the thermal decomposition of the explosive,a section in which the pressure increases rapidly due to the combustion of the explosive,and a section in which the pressure is maintained briefly when the shell breaks.A theoretical method is proposed to simulate the low-grade response of explosives in the shell during a slow cook-off.First,the Fluent software is used to calculate the temperature distribution of the explosive before ignition.It is assumed that a thermal decomposition reaction occurs in the region where the temperature is higher than the RDX decomposition temperature,and the RDX is consumed.The thermal decomposition coefficient k is introduced to describe the amount of the explosive where the thermal decomposition reaction occurred.On this basis,an improved interior ballistic equation set is established to describe the rapid rise of the internal pressure of the shell due to the combustion of the explosive,and the MATLAB program is compiled to perform iterative calculations on the equation set.The theoretical values and the experimental values are in good agreement.Then,using the calculated pressure-time curve as the input condition,the nonlinear dynamics software is used to simulate the fracture of the shell under the internal pressure.This method is used to calculate the thermal decomposition coefficients and pressure-time curves in the shell after ignition at different heating rates.The results show that when the heating rate is 1.0 K/min,the pressure growth rate after ignition is significantly higher than in other processes.