Application of Probabilistic Maintenance Models for Selecting Optimal Inspection Rates Considering Reliability and Cost Tradeoff

In this paper, we study the application of probabilistic maintenance models to determine the optimal inspection rates considering the tradeoff between reliability and cost. The study considers several measures of reliability and costs, namely, first passage time from new state to failure state (FPT), unavailability, frequency of interruption, cost of inspection, maintenance and repair, interruption cost and loss of profit due to interruptions. Typically, the objective of maintenance optimization problems is to minimize or maximize one or more of the reliability and cost measures. In this work, we show that unavailability and frequency of interruption are implicitly included when the objective function considers the cost of inspection, maintenance and repair and the cost of interruption, respectively. A sensitivity analysis shows that it is more appropriate to incorporate FPT as a constraint. The objective of the optimization problem is set as minimizing total cost which is the sum of all considered cost measures. A grid search algorithm is employed to find optimal inspection rates. The analysis is performed using two probabilistic maintenance models. Results show that practical solutions can be obtained for the optimal inspection rates with the careful selection of appropriate probabilistic maintenance models.