成型炸药滑动摩擦系数的测试与修正

Measurement and Modification of Dynamic Friction Coefficient of Pressed Explosive

为研究动摩擦系数对于成型炸药摩擦点火的影响,利用自行设计的基于落锤的摩擦测试系统,以8701压装成型炸药为研究对象,研究了不同压力环境下成型炸药与45号钢之间的动摩擦系数。试验结果表明,当界面压力由1 MPa升高到10 MPa时,动摩擦系数将由0.28降低至0.10,说明动摩擦系数具有压力相关性。基于试验结果,提出了该炸药的摩擦系数计算模型。通过LS-DYNA二次开发,添加了试验所得摩擦系数计算模型,对8701炸药滑道试验进行了摩擦点火热力化耦合数值模拟。计算结果表明,修正的摩擦系数计算模型会延长炸药点火延迟时间,提高临界点火速度和临界点火温度,也说明考虑了压力相关性的摩擦系数计算模型对于研究成型炸药的摩擦点火问题有重要意义。

In order to investigate the effect of dynamic friction coefficient on the friction ignition of pressed explosive,8701 pressed explosive is tested on the friction testing system based on the drop hammer apparatus,and tthe coefficients of dynamic friction between 8701 pressed explosive and 45~# steel at different normal pressures are studied. The experimental results show that,when the normal pressure is increased from 1 MPa to 10 MPa,the dynamic friction coefficient is reduced from 0. 28 to 0. 10,indicating that the dynamic friction coefficient is dependent on pressure. A calculation model of the friction coefficient is proposed based on the experimental results and introduced into the LS-DYNA through secondary development. The thermo-chemo-mechanical coupling numerical simulation is conducted for the skid test of 8701 pressed explosive. The calculated results show that the improved calculation model of friction coefficient prolongs the ignition delay time,increases the critical ignition velocity and raises the critical ignition temperature. The proposed model can be used to study the non-shock friction ignition problem.