基于随机载荷和强度退化的可靠性灵敏度分析

针对随机载荷和强度退化所引起的动态可靠性问题，将载荷和强度同时考虑成随机过程，利用顺序统计理论得出最大等效载荷，利用Gamma过程来描述机械零件的强度退化过程，并对零件进行动态可靠性建模.在此基础上，运用随机摄动理论和四阶矩技术给出了动态可靠性灵敏度的求解公式，解决了参数服从任意分布的灵敏度求解问题.以零件螺栓为例建立了可靠性动态模型，给出了各参数变量的灵敏度随时间变化的动态曲线，并用Monte Carlo方法进行了验证，结果表明所建立的模型能准确反映出机械零件的可靠性随使用时间的变化规律.

Reliability Sensitivity Analysis Based on Random Load and Strength Degradation

In order to solve the dynamic reliability problem caused by random load and strength degradation， the load and strength are considered as stochastic processes simultaneously. The maximum equivalent load is obtained by using the theory of sequence statistics， the strength degradation process of mechanical parts is described by Gamma process， and the dynamic reliability model is established. Consequently using the stochastic perturbation theory and the four-order moment technique， the solution formula for the dynamic reliability sensitivity is derived， solving the sensitivity problem of the parameters from arbitrary distribution. For variation， a dynamic reliability model for screw bolts was established. The dynamic curves of the sensitivity of each parameter variable vs. time were calculated with the said model， and were also verified by Monte Carlo method. The results show that the established model indicates the rule of reliability change of mechanical parts vs. time accurately.