燃烧固体药柱内腔表面的典型裂纹及其力学行为

根据燃烧环境中高装填固体推进剂药柱内应力的分布特征，提出了药柱内腔表面的两种典型裂纹， 即横向表面裂纹和纵向表面裂纹， 并分别采用方坯药柱和圆盘药柱表面预制的裂纹进行了模拟。比较燃气作用下两种药柱的有限元分析结果， 明确了挤裂模式对于燃烧环境中固体药柱表面裂纹问题的适用性。这些结论与实验观测现象非常吻合， 对实际发动机工作环境中固体药柱表面裂纹的力学行为预示和故障分析有着重要的指导意义。

TWO TYPES OF CRACKS ON CAVITY SURFACE OF HIGH LOADED SOLID PROPELLANT GRAIN

Associated with the characteristic of stress distribution in the high loaded solid propellant grain under combusting condition, two types of cracks on its cavity surface, the transverse surface crack and the longitudinal surface cracks,are taken into accounted. Respectively, one brick shaped experimental grain and another disc shaped one are employed for simulating above two types of cracks.Through numerical approach by FEM, the Squeezing Propagation Mode (SPM) is concluded to be rational for describing single surface crack propagation of combusting grain. In detail, this model is denoted by an empirical formula, which illustrates effects on transverse tearing stress of the surface crack tip due to three factors, such as pressure of combusting gases on main burning surface, pressure of gases in the gap of surface crack, and deepness of surface crack. According to this model, the longitudinal surface crack is found easier to propagate than the transverse surface crack