Availability optimization model for stochastically degrading systems under preventive replacement and minimal repair

This paper deals with a system maintenance optimization problem. The system to be maintained is assumed to be continuously monitored and subject to stochastic degradation. The proposed maintenance model considers three types of maintenance actions: minimal repair, preventive maintenance(PM)and replacement. PM are performed at dates kT (k = 1,2,...) while minimal repair are executed at failure occurrence during a PM cycle. The system is completely renewed whenever its corresponding accumulated operating time reaches a given value. The objective of the proposed maintenance optimization model consists on finding the joint optimal PM period together with the number of PM actions to be performed before replacing the system so as to maximize its average availability. A mathematical optimization model is proposed and the solution of which is addressed in a particular case where the system lifetimes are Weibull distributed. A numerical example is provided to illustrate the proposed maintenance optimization approach.