OPTIMAL REPLACEMENT POLICY FOR A DETERIORATING PRODUCTION SYSTEM

An optimal replacement policy for a deteriorating production system is considered. A minimal repair model is defined which assumes the syste m to be replaced after a specified time, during which a number of fail ures may occur The probability of failure can be given any arbitrary ( increasing) form. The model is based on a technique which permits to d eal with large repair times (non-negligible with respect to the replac ement time and the interval time) and to calculate the probability of k breakdowns over the replacement interval rigorously. The average dow ntime relevant to k minimal repairs is obtained, on the contrary, from a semiempirical formula that appears in good agreement with the resul ts of Monte Carlo simulations. The theory permits an accurate analysis of the error that is introduced when move conventional and approximat e models are used