围压下固体推进剂的破坏机理分析

贴壁浇筑的固体发动机推进剂药柱在点火状态下处于三向围压状态,而环向承受拉应变,亟待对围压下推进剂的破坏机理展开研究。基于自研的围压加载试验系统,通过开展推进剂在不同围压、温度和应变率下的单轴拉伸试验来研究围压、温度和应变率的耦合作用对推进剂力学行为的影响。针对围压下推进剂的力学响应特征,通过细观力学仿真进一步研究围压下推进剂的破坏形式,同时借助电镜扫描试验分析推进剂试样断面的形貌特征,通过试验和仿真相结合的手段分析了围压下推进剂的破坏机理。研究结果表明,围压下推进剂的损伤界面显著减少,且随着围压载荷的逐渐增加,推进剂的损伤形式从以颗粒脱湿为主转变为以颗粒破碎为主。

Analysis on the failure mechanism of solid propellant under superimposed pressure

In the ignition state, the SRM (solid rocket motor) grain with wall pouring is in the state of superimposed pressure, while the circumferential direction of SRM inner bore is under tensile strain. It is urgent to carry out related research on the failure mechanism of propellant under superimposed pressure. The mechanical behavior of solid propellant under coupling effect of superimposed pressure, temperature and strain rate was investigated through uniaxial tensile tests at different pressure, temperature and strain rates using self-developed superimposed pressure loading system. According to the mechanical response characteristics of the propellant under superimposed pressure, the failure modes of the propellant under superimposed pressure were further studied by means of meso-scale mechanical simulation. At the same time, the morphologic sectional features of the propellant specimens were analyzed by means of scanning electron microscope test. The failure mechanism of the propellant under superimposed pressure was found out by means of combining test and simulation. The results show that the damage interfaces of propellant decrease significantly under superimposed pressure, and with the increasing of superimposed pressure, the damage form of propellant changes from particle dewetting dominated to particle breakage dominated.