Reliability assessment of a degradable system with fuzzy lifetime distribution

The reliability estimation of a gracefully degradable system under fuzzy environments is proposed in this paper. The fuzzy parameters are assumed to be fuzzy random variables with fuzzy probability distributions and a computational procedure is developed to evaluate the fuzzy reliability function and its α-cut sets. In order to achieve this purpose, a Markov model of a 3-unit gracefully degradable system with coverage factor is developed to estimate the reliability when the lifetimes of components are described using fuzzy exponential distribution. The proposed methodology may be simply extended to the case of general lifetime probability distributions.