Reliability and maintenance analysis of a degradation-threshold-shock model for a system in a dynamic environment

In this paper, a degradation-threshold-shock model for a system in a dynamic environment is studied. Unlike most existing works assuming the independence between different failure mechanisms, this study considers a two-fold stochastic dependence between the degradation process and the shock arrival process. First, the evolutions of the two processes depend on the changing environment; secondly, shocks may trigger the system failure or increase the degradation level alternatively. The degradation is generally described by a monotone Stochastic process. Upon periodical inspection, the system is preventively replaced whenever its degradation level exceeds a pre-determined threshold or failure occurs. Under this policy, the reliability measures, the maintenance costs in the short-run and long-run, and the optimization of the maintenance cost with respect to the decision parameters: the preventive maintenance threshold and the inspection period are investigated. Theoretical results are presented and numerical examples are given to illustrate the applicability of the proposed model. (C) 2020 Elsevier Inc. All rights reserved.