柔性接头结构应力经验公式适用性

设计了接头球半径为8cm的柔性接头及其增强件环向应力电测系统，测试了不同燃烧室压强和摆角条件下增强件的环向应力，并与现有经验公式、有限元分析结果进行了对比，基于有限元分析研究了接头球半径变化对增强件环向压缩应力的影响，提出了新的接头球半径在6~10cm范围内增强件环向压缩应力估算公式，另外研究了喷管喉径对柔性接头结构应力的影响，讨论了冷试容器压强和热试车发动机燃烧室压强换算公式的适用性。结果表明:增强件环向压缩应力试验测试结果和有限元计算结果吻合较好，现有增强件环向压缩应力经验公式估算结果值得商榷，柔性接头冷试结构应力与热试结构应力是不同的，冷试容器压强和热试车发动机燃烧室压强换算公式对于增强件环向压缩应力是适用的，但是对弹性件切应力不适用。 

Applicability of empirical formula for flexible joint structural stress

An 8cm pivot radius flexible joint with reinforcement hoop stress measuring system was designed, and the reinforcement hoop stress due to different vessel pressures and vector angles was tested. The results were compared with the empirical formula and finite element analysis. Moreover, the effect of pivot radius on the reinforcement hoop compressive stress was investigated by finite element analysis. New formulas to compute the reinforcement hoop compressive stress for the pivot radius within the 6-10cm were proposed. The effect of throat diameter on the reinforcement hoop compressive stresses of flexible joint was also studied, and the applicability of conversion empirical formula between cold-flow vessel pressure and hot fire motor pressure was discussed. Results showed that a good agreement for the reinforcement hoop compressive stress between test and finite element analysis was obtained. Empirical formulas for reinforcement hoop compressive stresses were not applicable. The flexible joint structural stresses in vessel and the fire test of soild motor rocket were different. The reinforcement hoop compressive stresses for the hot fire test of flexible nozzle can be converted by the joint test in vessel through empirical formula. The elastomer shear stresses were more serious for the joint test in vessel than the fire test of solid motor rocket with flexible nozzle.