Reliability and opportunistic maintenance for a series system with multi-stage accelerated damage in shock environments

In this paper, a new shock model is proposed to fit the situation that the damage process of the component is accelerated with the increase of the degree of damage in shock environments. Shocks with the same magnitude may have more serious consequences as the component gets worse and component states are divided into different stages according to the degree of damage. Reliability indexes of a series system which consists of two components with the above characteristics are derived by using a Markov renewal process. Then, an opportunistic maintenance strategy is proposed for the system and an optimization model is constructed to obtain the optimal maintenance solutions. Finally, a numerical example for a two-rolling bearing system of a wind turbine is presented to illustrate the proposed shock model and maintenance strategy. Sensitivity analysis of maintenance costs is also discussed in order to improve the reliability of the proposed model. This study is of reference value and application significance for similar series systems.