Maintenance policy for a non-stationary deteriorating system

This paper deals with the maintenance optimization of a system subject to a stressful environment. The behavior of system deterioration can be modified by the environment. Reciprocally, the environment condition can be influenced by the system state and so, a change in the environment can be an indicator of the system state. We propose a condition-based maintenance decision framework to tackle the potential variations in the system deterioration, and especially in the deterioration rate, and the new information on the system state given by the evolution of the environmental variable. In this work, a degradation model is first developed to integrate the reciprocal influence on the system behaviour and the environment. A specific maintenance policy is constructed which combines a classical condition-based maintenance policy for the system state with a condition monitoring method to track the environmental changes. A long-run maintenance cost criteria is developed and numerical experiments are provided to highlight the benefits of our approach. The main conclusion of this study is the necessity to take into account the environment influence on the system state and we provide here an adequate maintenance framework for the decision-maker.