Overhaul Scheduling, considering the limited access to spare parts, reliability, and equipment availability by using fuzzy data

This article presents a mathematical model to develop the optimal planning for equipment overhaul under limited access to spare parts, uncertainty, and lack of accurate and complete information. The parameters of repair cost, demand, device efficiency, the selling price of each product unit, and production rate are considered fuzzy parameters. First, the system availability is modeled. The results are used in the development of a non-linear mixed integer programming model so that by solving it, the time of equipment overhaul can be determined in such a way as to minimize the total costs of repairs and operation. The presented approach is implemented for a numerical example, including a hypothetical production system. Finally, with the exact solution, using GAMS software, the optimal answer to the desired problem has been obtained and analyzed. The optimal solution sensitivity analysis facing the change of the main parameters of the model is done, and the results are shown in the graphs. Then the problem is resolved again using the fuzzy optimization approach, and the results are compared with the previous solution method. These results indicate that the fuzzy approach has excellent flexibility in transferring decision-maker's expectations to the modeling process. In this way, the analyst's opinion regarding the prioritization of the objective functions can be well reflected in the mathematical programming model.