Inspection-based Replacement Optimization Integrating Discrete and Continuous System States

Multi-phase, particularly two-phase failure process is widely seen in industrial asset management. This study addresses a joint state-threshold-integrated inspection-based replacement planning model with regard to two-phase continuous failure process. The system is decided to be renewed when equally spaced inspections reveal: (a) the hidden defective state, (b) the performance reduction attaining a threshold and (c) the malfunction occurrence. The expected cost rate model is formulated, and the optimal decision-making in regard to inspection interval and degradation threshold is derived. The applicability and superior performance of this proposed policy is verified via a case study of high-speed railway device.