关键词: 状态维修, 非周期检测, 不完美维修, 备件订购, 延迟时间

Abstract: A jointly policy of condition-based maintenance (CBM) and spare ordering is proposed for a single-unit system/critical component subject to a two-stage delay-time process. A non-periodic inspection policy with various intervals is presented, in which the system is detected with the relatively longer interval T₁ during the initial deterioration process, but with a shorted interval T₂ after the defective state is firstly found by an inspection. While, the spare is ordered and imperfect maintenance (IPM) is carried out. In the subsequent deterioration process, IPM is required and performed once the defective state is revealed until the number of IPM exceeds the threshold N_max; then, a preventive replacement is needed. If a failure occurs within the inspection interval, a corrective replacement arises. According to the system's state and the spare's availability, all possible renewal events and the corresponding joint decisions are discussed and then the objective function to minimize the expected cost per unit time is established using the renewal award theorem for optimizing T₁,T₂, N_max. The results fromthe numerical example indicate that the proposed policy decreases the expected cost per unit time compared to the comparative models.

Key words: condition-based maintenance, non-periodic inspection, imperfect maintenance, spare ordering, delay-time