固体发动机药柱完整性失效的判据

Failure criterion of solid motors at ignition pressurization loading

固体发动机工作过程中,燃烧室药柱处于三向受压状态下,围压条件对推进剂力学性能有增强。该增强作用在细观结构上表现为延缓推进剂中微裂纹与真空孔穴(脱湿)的出现,并限制其在固体填料周围粘合剂中的扩展;在宏观力学性能上表现为在低温高应变率下推进剂的最大伸长率εm由常压下的较小值增大到接近断裂伸长率εb。通过围压环境对推进剂力学性能的影响分析,提出以推进剂断裂伸长率εb作为药柱在工作内压下的失效判据,并结合某翼柱型装药结构的有限元分析、完整性评估及地面试验,验证了该判据的合理性。

During the working process of solid rocket motors,the propellant grains are under the three-dimensional pressure,which increases the mechanical properties of the propellant. The enhancement seems to delay the occurrence of micro-cracks and vacuum cavities（ dewetting） in the propellant,and meantime limit their extension in the binder surounding the solid fillers in the micro-structure.In the case of macro-mechanical properties,it shows that the maximum elongation of the propellant increases from a relatively small value under normal pressure to near the breaking elongation at low temperature and a high strain rate. Based on the analyses of the effects of the confining pressure on the mechanical properties of the propellant,the breaking elongation is proposed as the failure criterion under operation pressure.On the basis of the finite element analysis,integrity evaluation and ground test of the SRM with a finocyl grain,the rationality of the criterion is verified.