Multi-level maintenance and inventory joint optimization for a k-out-of-n hyper-system considering the selection of suppliers with incentive discount policies

Maintenance outsourcing is increasingly applied in industries that rely on complex and critical systems. Effective preventive maintenance (PM) scheduling and spare parts inventory control determine the profitability of maintenance outsourcing services. A multi-level opportunistic maintenance and inventory control joint optimization (M-OMICJO) policy is thus proposed to maximize maintenance outsourcing profit. This study focuses on a hyper-system composed of B systems with shared maintenance resources. Each system is a k-out-of-n: G structure, which faces the maintenance challenges of high-reliability requirements and economic dependence among machines. Besides, spare parts can be purchased from different suppliers based on prices and incentive discounts. We construct a multi-level interactive optimization structure. At the machine level, sequential optimal PM intervals are scheduled based on degradation trends and spare part prices. At the system level, opportunistic maintenance schemes are obtained based on maintenance profit savings (MPS), maintenance resource constraints and intersystem coupling relationships. At the hyper-system level, the multi-system coordinated maintenance personnel dispatching and the multi-supplier ordering scale effect are realized via group PM sets rescheduling and spare parts order integrating. Finally, a numerical experiment has illustrated the effectiveness and robustness of this policy ensuring maintenance cost reduction and reliability improvement of the whole hyper system.