A reliability-based approach to optimize preventive maintenance scheduling for coherent systems

In this paper, the problem of reliability-based periodic preventive maintenance (PM) planning for systems with deteriorating components has been considered. The objective is to maintain a certain level of reliability with minimal total maintenance related cost. In the proposed approach, the planning horizon is divided into pre-specified inspection periods. For any given interval, a decision must be made to perform one of the three actions on each component (simple service, preventive repair and preventive replacement). Any of these activities has a distinct effect on the reliability of the components and the corresponding cost based on the required resources. The cost function includes repair cost, replacement cost, system downtime cost and random failure cost. It is assumed that the random failures follow a Non-Homogeneous Poisson Process. Minimum system reliability and PM resources are the main constraints considered. Since the problem under study is combinatorial in nature involving several non-linear decision variables, a simulated annealing algorithm is employed to provide good solutions within reasonable search time. Some illustrative examples have been solved to assess the performance of the proposed approach.