基于加速老化和实测载荷的立式贮存固体发动机药柱寿命评估

Service Life Prediction of Solid Motor during Vertical Storage Based on Accelerated Aging and Actual Loadings

为预估立式贮存固体发动机药柱贮存寿命,综合考虑加速老化和实测载荷的影响,开展推进剂高温加速老化试验,得到推进剂延伸率的变化规律。分别对贮存老化后的发动机在固化降温/静态立式贮存/点火发射和固化降温/动态立式贮存两种载荷历程进行有限元分析,获取药柱危险点von Mises应变规律,并计算药柱在振动条件下的疲劳损伤。以延伸率和应变随时间的变化规律为依据,预估了发动机寿命。结果表明:推进剂延伸率随时间逐渐减小;药柱在重力载荷的长时间作用下会产生蠕变效应;药柱内部各点在实测振动载荷作用下产生周期性的应力,动态立式贮存半年的损伤值为0. 017 12;发动机贮存老化时间与立式贮存次数呈现负指数关系,其可允许的动态立式贮存次数为15次;考虑立式贮存时,总寿命介于8. 24~11. 75年;忽略立式贮存时,总寿命为17. 81年。

The influences of accelerated aging and actual loadings are both considered in predicting the storage life of solid motor grain during vertical storage. The variation law of the extensibility of propellant was obtained by high temperature accelerated aging test. The variation of von Mises strain of grain dangerous point and the fatigue damage of grain under vibration were obtained by the finite element simulation of motor under two loadings of curing/static vertical storage/blast-off and curing/dynamic vertical storage. Service life of motor was predicted according to the variation law of von Mises strain and extensibility with storage time. Test results show that the extensibility of propellant decreases with time;the creep effect appears in the grain under a long-term action of gravitational load,and the periodic stresses are generated at the points in the grain under actual loadings. The fatigue damage of grain storaged for half a year is 0. 017 12. The storage time has a negative exponent relation with vertical storage frequency,and the allowable vertical storage is 15 times. Its storage life during vertical storage is between 8. 24 and11. 75 years,and its storage life under horizontal storage is 17. 81 years.