晶体缺陷对HMX基PBX性能影响的理论计算

Theoretical Calculation of the Effect of Crystal Defects on Properties of HMX-based PBX

为研究晶体缺陷对奥克托今(HMX)基高聚物粘结炸药(PBX)性能的影响,分别建立了2种PBX“完美”模型和4种缺陷模型。采用分子动力学(MD)方法,对6种PBX模型进行了模拟计算,得到了感度、结合能、爆轰性能和力学性能参数并进行了对比。结果表明,晶体缺陷导致PBX炸药的键连双原子作用能和内聚能密度减小,分别下降2.46~5.72 kJ·mol^-1和0.0251~0.0544 kJ·cm^-3,表明缺陷模型的感度增加,安全性降低;缺陷模型的结合能下降509.61~1618.24 kJ·mol^-1,表明炸药的稳定性变差;缺陷模型的密度、爆速和爆压均下降,降幅分别为0.01~0.05 g·cm^-3、36.35~185.69 m·s^-1和0.36~1.79 GPa,其氧平衡和爆热的变化几乎可以忽略不计,表明缺陷模型的毁伤威力降低。晶体缺陷还导致PBX炸药的拉伸模量、体积模量和剪切模量分别下降0.062~1.772、0.261~1.188 GPa和0.012~0.685 GPa,体积模量与剪切模量之比增加0.002~0.366,位错和空位缺陷模型的柯西压分别下降0.822 GPa和0.479 GPa,掺杂和孪晶缺陷模型的柯西压分别上升0.114 GPa和0.491 GPa,表明缺陷模型的抗变形能力下降,柔韧性增强。

To investigate the effect of crystal defects on properties of HMX-based polymer bonded explosive (PBX),two defect-free models and four defective models were established. Using molecular dynamics(MD)method,different models were simulated and the sensitivity,binding energy,detonation performance and mechanical properties of different models were calculated and compared. Results show that the crystal defects cause the interaction energy of trigger bond and cohesive energy density to decrease by 2.46-5.72 kJ·mol^-1 and 0.0251-0.0544 kJ·cm^-3,respectively,indicating that the sensitivity of defective models is increased and safety is decreased. The binding energy of defective models is decreased by 106.89-231.65 kJ·mol^-1,meaning that their stability is deteriorated. The density,detonation velocity and detonation pressure of defective models are decreased by 0.01-0.05 g·cm^-3,36.35-185.69 m·s^-1 and 0.36-1.79 GPa,respectively. However,the variation of oxygen balance and detonation heat can be negligible. The variation of detonation parameter indicates that the damage power of defective models is weakened. Tensile modulus,bulk modulus,shear modulus of defective models are decreased by 0.062-1.772,0.261-1.188 GPa and 0.012-0.685 GPa,respectively. The ratio of bulk modulus to shear modulus is increased by 0.002-0.366. The Cauchy pressure of dislocation and vacancy defective models is decreased by 0.822 GPa and 0.479 GPa,while it is increased by 0.114 GPa and 0.491 GPa in doping and twin defective models respectively,indicating that the deformation resistance of the defective models is decreased and the flexibility is enhanced.