Remaining-useful-lifetime and system-remaining-profit based importance measures for decisions on preventive maintenance

We propose two types of importance measures for component selection in preventive maintenance. The first type evaluates the relative importance of a component in terms of how much the component restoration increases the remaining useful lifetime of the system. The second type of importance measures evaluates the contribution of a maintenance action on a component with respect to the profit that the system can generate during its remaining useful lifetime, considering system reliability, maintenance cost, and uncertain system profit over the remaining useful lifetime. The proposed importance measures take into account various maintenance actions including imperfect repair and replacement, combine the advantages of time-dependent and time-independent lifetime measures on evaluating component importance and are suitable to aid the preventive maintenance decisions on component selection at any time. A numerical example and an application in the preventive maintenance for a wind turbine system are provided to illustrate the proposed importance measures and to compare various time-dependent and time-independent lifetime importance measures.