Multi-phase sequential preventive maintenance scheduling for deteriorating repairable systems

In this paper, we present a novel multi-phase sequential preventive maintenance (PM) model with multiple maintenance objectives for repairable mechanical systems under deterioration. Although sequential PM scheduling has appeared in literature, conventionally the length of time between maintenance events in the later of replacement process changes very frequently, which has led to poor operability in practice, and has consequently brought a great challenge for maintenance managers. To solve this problem, the concept of multiple phases sequential PM, in which the replacement cycle is divided into several phases, each with equal PM intervals, is proposed to make the policy more suitable in practical applications. A new relationship between cost and maintenance quality, which considers the age reduction factor as a function of maintenance cost and system age, is established to describe the effect of maintenance. The maintenance modeling and optimizing problems are formulated using a multi-attribute value model (MAVM) and a computation algorithm is presented to find the optimum solution. A case study of examining equipment is presented to illustrate the performance of the proposed policy. A comparison with other methods is given to illustrate the effectiveness of our approach. Finally, a sensitivity analysis is performed on the optimality of the maintenance schedule based on related parameters.