关键词: 二阶可靠性方法, 可靠性指数, 失效概率, 失效区, 最小割集

Abstract: According to the nonlinearity and the multiple extreme value points of performance function, it is dealt with piecewise and a new computing method of failure probability based on the minimum cut set is put forwards. Multiple quadratic performance functions are used to replace the original complicated performance function piecewise, and the combination of failure domains of these quadratic performance functions is as close as to the failure domain of original performance function. The reliability indexes of quadratic performance functions are calculated by second order reliability method. All the minimum cut sets to describe the original failure domain are obtained by using the failure domains of quadratic performance functions according to the concept of the minimum cut set. All the minimum cut sets of equivalent failure domains were obtained to express the original failure domain by substituting quadratic failure domains with equivalent failure domains. Reliability index calculated by first order reliability method is redefined so that it could be suitable to the case that the origin of coordinates is in failure domain. And then, the combination of failure probabilities of multiple equivalent failure domains could be computed and the approximate probability of the original failure domain could be obtained. The example shows that the method is feasible and the calculation accuracy of failure probability could be improved greatly.

Key words: Failure domain, Failure probability, Minimum cut set, Reliability index, Second order reliability method