Selective preventive maintenance scheduling under imperfect repair

The demand for a system is sometimes available only for a finite time horizon. It thus becomes necessary to schedule maintenance activities during a given planning horizon such that the desired system performance is maintained and the available resources are optimally allocated. In this paper, a mathematical model is proposed for periodically planning preventive maintenance activities for a system comprising multiple components. Due to resource limitations, it may not be possible to perform all desired maintenance options; hence, a selective maintenance approach is used to find the components to be maintained and maintenance actions to be performed on the selected components. An imperfect maintenance based hybrid model is considered here which includes age reduction as well as hazard adjustment after maintenance. Due to the high dimension of the solution domain, evolutionary approach is used to solve the problem. The optimal number of intervals is found under reliability and maintenance time constraints. During each maintenance break, the optimal maintenance option is selected for each component such that the overall cost of maintenance and possible failures for the entire planning horizon is minimized. It is also found that considering one interval at a time will incur higher cost.