Optimizations problems for a k -out-of- n system under interval replacement

This paper studies interval replacement policies with minimal repair for the k-out-of-n system that consists of independent and identical components. The expected cost rate function of the k-out-of-n system was derived. The upper and lower limits of the optimal replacement interval were determined, and the optimal number of system components was obtained by minimizing the expected cost function. The proposed model assumes that the preventive maintenance of the system in the interval is more reasonable than the maintenance at the given time point. In comparison with conventional maintenance strategies, the developed policy offers greater flexibility and diversity. The findings of the present paper extend the results in the literature from age replacement policy to interval replacement policy. This study was illustrated through detailed numerical examples, and two specific practical systems were provided to verify the proposed model.