Opportunistic Maintenance for Heterogeneous Complex Systems Under Continuous Monitoring

We analyze the maintenance strategy for a complex system consisting of two types of components: non-monitored and monitored. Non-monitored components can only be maintained correctively upon failure. Monitored components are monitored continuously and are maintained when they become too degraded, i.e., just before its degradation level hits a threshold. There is an economic dependence between the components, which means that a maintenance intervention for one component can be used as an opportunity for preventive maintenance of monitored components: If the degradation level of a monitored component exceeds a preventive threshold at the time of another maintenance intervention, this component is maintained preventively. Evaluating the costs of a given maintenance strategy is time consuming, especially for a large number of monitored components. However, using semi-regenerative techniques instead of renewal techniques, we are able to drastically shorten the required computation time: For a system with ten monitored components, the computation time to evaluate the optimal maintenance strategy goes from more than a day to few seconds. We give numerical examples to illustrate our results.