Reliability and Mean Time to Failure of Unrepairable Systems With Fuzzy Random Lifetimes

In practice, the lifetimes of unrepairable systems contain both randomness and fuzziness. So it is appropriate to assume the lifetimes of systems to be fuzzy random variables. In this paper, the definitions of reliability and mean time to failure (MTTF) of unrepairable systems with fuzzy random lifetimes are given, respectively. Then basic mathematical models of unrepairable systems with fuzzy random lifetimes are established. Furthermore, the reliability and MTTF of series systems, parallel systems, series-parallel systems, parallel-series systems, and cold standby systems are discussed, respectively. Finally, some numerical examples are presented to illustrate how to calculate the reliability and MTTF of unrepairable systems with fuzzy random lifetimes.