A simple recursive Markov chain model to determine the optimal replacementpolicies under general repairs

A repairable system (machine) is subject to failure. At each failure epoch, a general repair is performed. Such repairs return the system to a working condition somewhere between 'good-as-new' (a perfect repair) and 'bad-as-o ld' (a minimal repair). An important question for such systems is at what t ime should a major overhaul be conducted to return the unit to a 'good-as-n ew' state. Two. policies are investigated in this research: (1) overhaul at fixed intervals and (2) overall at variable intervals by conducting each o verhaul on the first failure following a predetermined time. We show in thi s research that both of these policies can be analyzed using a simple recur sive Markov model thereby permitting the best of these policies to be ident ified in any particular situation. The Markov model is quite general, permi tting a wide variety of structures to be investigated.