Preventive maintenance for heterogeneous parallel systems with two failure modes

Abstract

The parallel structure in the reliability engineering is widely used in many industrial systems such as power generation systems, pump systems, production systems and computing systems. Designing the optimal maintenance policies for these parallel systems can minimize the operation cost while achieving a satisfying system availability. Previous studies have studied various maintenance optimization for parallel systems. However, little research has considered the multiple failure modes that widely exist in many real industrial systems. This research considers a parallel system that consists of heterogeneous components subject to two types of competing failures: a one-stage catastrophic failure and a two-stage delay-time failure. Inspections are conducted periodically to identify the state of each component. Three maintenance policies are proposed in this research. To find the optimal inspection interval, we analyze the renewal process of the system to minimize the long-term expected cost per unit time. A simulation procedure is proposed to evaluate the long-term expected cost per unit time. Numerical experiments are carried out to illustrate the applications of the proposed maintenance policies. The discussion provides useful insights on choosing the best policy under different system performance requirements.