University of Tehran Press Journal of Computational Applied Mechanics 2423-6713 56 4 2025 10 01 Computational Optimization of Preventive Maintenance Schedules in Repairable Mechanical Systems Using NSGA-II 882 911 103213 10.22059/jcamech.2025.398973.1554 EN Iman Bavarsad Salehpour Department of Industrial Engineering, Faculty of Engineering, University of Kurdistan, Sanandaj, Iran 0000-0003-3312-3704 Mahmoud Shahrokhi Department of Industrial Engineering, Faculty of Engineering, University of Kurdistan, Sanandaj, Iran Journal Article 2025 07 20 In this study, a computational framework is proposed for optimizing preventive maintenance scheduling in complex mechanical systems, with a focus on minimizing total maintenance costs while preserving system availability and mechanical reliability. The model incorporates multi-level maintenance actions—including inspection, repair, and component replacement—over a defined planning horizon. A nonlinear integer programming formulation is developed to capture cost elements such as random failure, repair, replacement, and planned downtime. To address the combinatorial complexity of the problem, a Non-Dominated Sorting Genetic Algorithm II (NSGA-II) is employed to generate near-optimal solutions. The proposed method is applied to a real-world Cathodic Protection System used in steel gas distribution networks, which are critical mechanical infrastructures subject to electrochemical degradation. Results demonstrate a 36% reduction in total maintenance costs, highlighting the effectiveness of the model in improving asset performance and extending system life through optimized maintenance strategies. https://jcamech.ut.ac.ir/article_103213_fdca8e4b49c4d4f633d82053b461a74f.pdf