PROJECT TITLE :

Scheduling Preventive Maintenance as a Function of an Imperfect Inspection Interval

ABSTRACT:

This paper considers a system with periodic inspections and periodic preventive maintenance (PM) to detect and correct hidden failures that generate a penalty price per unit time undetected. Imperfect periodic inspections (IPIs) occur at a selected interval t, and detect hidden failures with chance p ∈ (0,one). Both reactive maintenance (RM), performed when a hidden failure is detected by an IPI, and PM, performed at a selected time (n+1)t, renew the system. The target is to determine the optimal frequency t and amount n of imperfect inspections between PM such that the expected cost (which includes the prices of undetected failures, IPIs, PM, and RM) per unit time is minimized over an infinite horizon. We tend to analytically establish conditions for the existence of a finite optimal t for a given value of n, and discuss the asymptotic behavior of the objective function for large n and t. These results are any exploited to describe convergence properties of a proposed approach for finding a globally optimal solution. Also, for the special case of a Weibull time-to-failure distribution, we tend to derive conditions that guarantee the uniqueness of a regionally optimal solution for a given worth of n.