超弹性橡胶膜片疲劳寿命及可靠性分析

Fatigue Life and Reliability Analysis of Superelastic Rubber Diaphragm

为了提高液体火箭发动机阀门可重复使用性,以某液体火箭发动机球阀气动执行机构的超弹性橡胶膜片为对象,提出了一种超弹性橡胶膜片疲劳寿命及可靠性分析方法。首先针对阀门气动执行机构进行非线性有限元分析,获得超弹性橡胶膜片应力场。其次基于超弹性橡胶连续损伤理论,对超弹性橡胶膜片的疲劳寿命进行计算。之后在中心复合试验设计(Central Composite Experimental Design,CCD)基础上建立了膜片疲劳寿命响应面代理模型,研究了结构尺寸、材料属性和工作载荷对寿命的影响规律。最后结合蒙特卡洛法(Monte-carlo)和可靠性理论进行了超弹性橡胶膜片的可靠性计算。计算结果表明,方法可以针对超弹性橡胶膜片的疲劳寿命及可靠性问题进行准确计算。研究发现疲劳寿命随下腔圆角和工作气压的增大而增大,材料属性能够在一定范围内影响其疲劳寿命值,膜厚度的变化对膜片疲劳寿命影响程度较小。可以通过增大下腔圆角和控制工作气压波动来提高其疲劳寿命及提升可靠性。

In order to improve the reusability of liquid rocket engine valve,a method for fatigue life and reliability analysis of the superelastic rubber diaphragm of a liquid rocket engine ball valve pneumatic actuator is proposed.Firstly,nonlinear finite element analysis is carried out for pneumatic actuator of valve,and the stress field of superelastic rubber diaphragm is obtained.Secondly,the fatigue life of super elastic rubber diaphragm is calculated based on the continuous damage theory of superelastic rubber.Then,a proxy model of diaphragm fatigue life response surface is established based on central composite experimental design(CCD),and the effects of structural size,material properties and working load on the fatigue life are studied.Finally,the reliability of the superelastic rubber diaphragm is calculated by using Monte Carlo method and reliability theory.The calculation results show that the proposed method can accurately calculate the fatigue life and reliability of the superelastic rubber diaphragm.It is found that the fatigue life of the diaphragm increases with the increase of fillet Angle and working pressure.The material properties can affect the fatigue life of the diaphragm in a certain range,and the change of film thickness has little influence on the fatigue life of the diaphragm.The fatigue life and reliability can be improved by increasing the lower chamber fillet and controlling the fluctuation of working pressure.