Modeling and analyzing repairable safety-critical series-parallel system

The repairable safety-critical series-parallel system has working, fail-safe, and fail-dangerous states. This paper studies the repairable safety-critical series-parallel system by considering its component lifetime possessing general distribution. We first respectively derive the reliability and safety indices of the system including probabilities that the system in these states and mean times for the system under two different failure ways. And then the non-uniform aging model of the system is built, and two virtual age criterions are employed to study the expected repairs of the system during different aging stages of its whole operational cycle. Finally some illustrative examples are employed to show the procedures. These formulas are derived without considering component lifetime distribution assumptions, which have important meanings for improving the system reliability, safety, and maintenance.