Optimal Inspection Policy for a Three-Stage System With Imperfect Inspection and Repair

Many production systems undergo a multistate deterioration process before failure, during which inspection and repair are used to detect and remove the defects. Given the limitations of technology and random noise, inspection and repair are always imperfect. This study considered imperfect inspection and repair for a system subject to a three-stage degradation process. The concepts of virtual age and the improvement factor were adopted to characterize the imperfect repair effect. To verify the effectiveness of the proposed model, we applied it to the case of a steel converter plant and used the genetic algorithm to search for the optimal solution. The numerical results indicated that an optimal arrangement of inspection policy could significantly reduce maintenance costs.