柔性接头疲劳摆动寿命分析研究

Analysis of Fatigue Properties and Vectoring Life of Flexible Joint

关键词:  固体火箭发动机  柔性接头  裂纹成核理论  疲劳失效  摆动寿命

Key words:  Solid rocket motor  Flexible joints  Crack nucleation theory  Fatigue failure  Vectoring life

摘要:

通常柔性接头在进行全周大角度摆动时易发生疲劳失效。为探究柔性接头摆动寿命与损伤机理，基于裂纹成核理论，提出了一种预估柔性接头疲劳寿命有限元计算方法，并分别预估了1MPa，3MPa，5MPa，8MPa内压下柔性接头摆动4.5°的疲劳寿命。结果表明，柔性接头疲劳失效最易发生于与前法兰相连的弹性件上，在内压3MPa左右时疲劳摆动次数最大。随后开展了四重片剪切疲劳试验，对仿真寿命预估结果进行验证。四重片剪切疲劳试验与仿真结果对比，循环寿命次数相差15%以内，表明了该寿命预估计算方法的正确性。

Abstract:

Generally， the flexible joint is prone to fatigue failure when it vectors at a large angle throughout the circumference. In order to study the vectoring life and damage mechanism of flexible joint， a finite element calculation method for predicting the fatigue life of flexible joint is proposed， based on the crack nucleation theory， and the fatigue life of flexible joint with vectoring of 4.5° under 1MPa， 3MPa， 5MPa and 8MPa internal pressure is predicted respectively. The results show that the fatigue failure of the flexible joint is most likely to occur on the elastic parts connected with the front flange， and the number of vectoring times is the largest when the internal pressure is about 3MPa. The four-piece shear fatigue test was carried out to verify the simulation life prediction results. The difference between the simulation results and the four-piece shear fatigue test results is less than 15%， which indicates the correctness of the life prediction method.