Kah. Kobbacy et al., A FULL HISTORY PROPORTIONAL HAZARDS MODEL FOR PREVENTIVE MAINTENANCE SCHEDULING, Quality and reliability engineering international, 13(4), 1997, pp. 187-198
This paper is concerned with the development of a realistic preventive
maintenance (PM) scheduling model. A heuristic approach for implement
ing the semi-parametric proportional-hazards model (PHM) to schedule t
he next preventive maintenance interval on the basis of the equipment'
s full condition history is introduced. This heuristic can be used wit
h repairable systems and does not require the unrealistic assumption o
f renewal during repair, or even during PM. Two PHMs are fitted, for t
he life of equipment following corrective work and the life of equipme
nt following PM, using appropriate explanatory variables. These models
are then used within a simulation framework to schedule the next prev
entive maintenance interval. Optimal PM schedules are estimated using
two different criteria, namely maximizing availability over a single P
M interval and over a fixed horizon. History data from a set of four p
umps operating in a continuous process industry is also used to demons
trate the proposed approach. The results indicate a higher availabilit
y for the recommended schedule than the availability resulting from ap
plying the optimal PM intervals as suggested by using the conventional
stationary models. (C) 1997 John Wiley & Sons, Ltd.