(A) study on imperfect preventive maintenance models with two types of failures

Abstract

This thesis presents the optimal age-policy with imperfect actions in preventive maintenance(pm). The imperfectness of preventive maintenance is categorized by two parts : 1) the preventive maintenance is imperfect in the sense that it can cause failure of a non-failed system, 2) the system after pm has the same failure rate as it has been before pm with probability p. The reliability behaviour of systems is investigated, in the case of which two types of failures can happen. Type 1 failure is removed by minimal repair and type 2 failure is removed by replacement. A lower bound on mission reliability, as well as long-run cost-rate, is considered as a criterion.