Generalized reliability models and preventive maintenance policy for systems subject to competing dependent failure processes

Abstract

We investigate in this paper systems reliability analysis using shock models. Two known modeling approaches are considered: the first one is a mixed shock model and the second one is based on mixed degradation and shocks. We generalize each of these two models considering a vulnerability level, L(t), which is a shock magnitude under which a shock has no effect on the system degradation process. A preventive maintenance policy is proposed for systems subject to mixed degradation and shocks. A mathematical model is developed in order to determine simultaneously the optimal age T* and the optimal number of shocks N* at which a preventive maintenance action should be undertaken (whichever comes first), minimizing the average long-run maintenance cost per time unit. Obtained numerical results are discussed.