Opportunistic maintenance model for load sharing k-out-of-n systems with perfect PM and minimal repairs

Abstract

This paper proposes a novel opportunistic maintenance model for load-sharing k-out-of-n systems where partial failure is allowed with corrective and preventive maintenance combined. We consider a load-sharing k-out-of-n system with identical components having exponential distribution subject to a constant load. Upon components failure, the workload will be redistributed to the survived components increasing the failure rates. This creates a failure dependency among components which complicates finding the optimal cost-effective maintenance policy. The proposed maintenance model consists of two intervals where minimal repairs are sufficient for the failed components until time In the second interval, two scenarios may occur: Corrective Maintenance (CM) of the failed components together with opportunistic Preventive Maintenance (PM) of the survived ones are performed once failures occur, or we reach the end of policy whichever takes place sooner. Tampered Failure Rate (TFR) model is used to explain the failure dependency and failure rate change of load-sharing components. In this paper, we find the optimal and for the opportunistic maintenance policy that minimizes the total expected cost over the lifecycle of a load sharing k-out-of-n system. We derive the analytical solution and present an application to a computer numerical control (CNC) system of a 3-out-of-7 system to illustrate the proposed model.