AGE REPLACEMENT POLICY WITH AGE-DEPENDENT MINIMAL REPAIR.

This paper studies a maintenance policy that is concerned with both preventive replacements and the actions to be taken at failures. The proposed policy prescribes age preventive replacements and (minimal) repair at failure if the repair cost is below some limit (otherwise the unit is replaced). The repair-cost-limit is allowed to be age-dependent. The model considered generalizes the various cost factors, the repair cost distribution and the preventive and failure replacement costs, by allowing them to be age-dependent as well. Running costs of the unit, again possibly age-dependent, are also incorporated into the analysis. The expected cost per unit time in the long run - the cost objective function of the policy - is computed in terms of the decision parameters of the policy: the repair-cost-limit function and the critical age for preventive replacement. The optimal value of these parameters is numerically calculated for two examples, and the gains of the proposed policy compared with a constant repair-cost-limit policy and a basic age-replacement policy are evaluated.