An inspection-maintenance strategy for heterogeneous systems with measurable degradation

Products are often designed to be very reliable such that even a defective unit can function for a long time. Instead of degradation-based burn-in for these kinds of products, this study advocates an inspection-maintenance strategy to make use of these weak units. Under this policy, an inspection is conducted in the midway of the system operation with the purpose of identifying and replacing a defective unit, while an age-based preventive replacement is carried out at a later stage to prevent a wear-out failure. By capitalizing on the gamma process, the mean cost rate function of this policy is derived. Optimal inspection and preventive maintenance times are discussed. We compare the average cost of this policy with the joint burn-in and maintenance policy to demonstrate its advantages.