Analysis of a production/inventory system with randomly failing production unit subjected to a minimum required availability level

In this paper, we consider a repairable production unit subject to random failures, which supplies input to a subsequent assembly line. The production unit is submitted to a maintenance action as soon as it reaches a certain age 'T' or at failure whichever occurs first. A buffer stock 'h' is built up in order to guarantee a continuous supply of the assembly line at a constant rate during repair and preventive maintenance actions whose respective durations are random. This production unit operating strategy is investigated taking into account a minimum required stationary availability level 'A'. We find the optimal operating characteristics (h* and T*) which minimize the total average cost per time unit and satisfy the availability constraint.