Fuzzy time-variant reliability analysis of mechanical structure based on generalized degradation

The character that the specimen number of on-orbit mechanical products in space is small leads to the fuzziness of relative parameters and the dynamic degraded failure criterion. The existing fuzzy reliability model mainly aims at static problems, which cannot describe the time-variant and fuzzy problem. This paper proposes a fuzzy time-dependent reliability modeling and analysis method which is based on the interference model of generalized stress-strength and takes account of the fuzziness of both variables and failure criterion at the same time. First, fuzzy criterion can be transferred into random variables equivalently. Then the theory of cut set in fuzzy math can be used to deal with the fuzzy random variables, and thus the fuzzy time-variant reliability model is built. After that, a new method (FPHI2) is presented, based on the method of PHI2 which is a tool for time-variant reliability computation based on the outcrossing approach, to compute the fuzzy time-variant reliability. In the end, a numerical case and an engineering case are provided to verify the feasibility of the proposed method.