Maximization of system reliability with the consideration of component sequencing

Highlights: • Component order affects the reliability of standby systems with imperfect switch. • The optimal sequence depends on mission time, reliabilities of parts and switch. • New redundancy allocation problem with mixed components (RAPMC) is proposed. • The RAPMC involves the determinations of the sequence and redundancy strategy. • The RAPMC achieves higher system reliability than the previous version of RAPs. This article deals with the optimal reliability design for a system with heterogeneous components, i.e., redundancy allocation problem with mixed components (RAPMC). Furthermore, it is confirmed that the component sequence affects the reliability of a cold-standby system with an imperfect fault detector/switch, and the optimal order depends on the mission time of the system, the reliabilities of a switch and components. Thus, the suggested RAPMC includes a new decision variable for the optimal component order. The usefulness of the RAPMC has been demonstrated by comparing the optimal system reliabilities by it and other RAPs in a well-known example. That is, under the same constraints on system specifications such as cost and weight, it recommended the system configuration with higher reliability than the previous version of RAPs. Finally, introducing the notion of the optimal component sequence for cold-standby subsystems results in a meaningful improvement in the system reliability.