Performance measures for a deteriorating system subject to imperfect maintenance and delayed repairs

Abstract

A system subject to an accumulating deterioration and continuous monitoring is analyzed in this article. The system deterioration is modeled using a gamma process, and the system is considered as failed when its degradation level exceeds a failure threshold. The maintenance team lasts a fixed time to start the maintenance actions. To prevent downtime, an alert signal is sent in advance to the maintenance team when the degradation level of the system exceeds a preventive threshold. At the maintenance time, three maintenance actions can be performed: preventive replacement, corrective replacement, and imperfect repair. We assume that the repair is imperfect, in a sense that it reduces a part of the degradation accumulated by the system from the last maintenance action. Under these assumptions, integral equations fulfilled by different performance measures are obtained. Numerical examples are given that illustrate the analytical results.