Reliability and Maintenance Models for a Competing-Risk System Subjected to Random Usage

In this paper, a reliability model is developed for systems subjected to competing risks and random usage. Degradation process, random shocks, and random usage may cause system failure. We assume that random usage which is an additional time-scale can directly affect the degradation measure. In this regard, we study the effect of random usage on degradation process. We propose a time-based and a condition-based maintenance model to maximize the availability of this system. Maintenance models are considered with and without cost constraint. The performance of the maintenance policies are compared through a numerical example.