Reliability and maintenance analysis of coherent systems subject to aging and environmental shocks

In reliability engineering, each component of the system, in addition to internal failures, is usually subject to lethal external shocks. Usually, the random shocks are produced by a random environment, and modeled by a stochastic process. In this paper, using the theory of signature and survival signature depending on whether the components of the system are of one type or several types, a general approach in assessing the system reliability is presented. We also propose some preventive maintenance strategies for a multi-component system whose components are subject to both internal failures and fatal shocks. In each policy, based on the maintenance costs of the system and its components, a cost function is computed as a criterion to be optimized. The signature-based representation of the system reliability is especially useful to maintain the system in optimal conditions by considering the component repair costs. To illustrate the theoretical results, extensive graphical and numerical examples are presented. • A general approach in assessing the system reliability is presented. • The system is subject to internal failures and external shocks. • The theory of signature and survival signature is used. • Some optimal maintenance models are proposed.