Condition-Based Maintenance Scheduling Integrating Multi-Level Defect Information under Multivariate Environmental Affection

The degradation resistance of equipment in natural environments directly impacts its operational safety and performance, underscoring the significance to accurately describe the underlying degradation process followed up by timely maintenance procedures. In this study, we delve into a multi-state corrosion degradation process under multifaceted environmental impacts, whose prevention is exemplified by a multi-stage condition-based maintenance scheduling. To be specific, we use a delay-time concept to capture the health transition process, which defines a minor and severe defects stage prior to ultimate failure. By integrating failure-based corrective maintenance, inspection-based preventive maintenance and proactive coating action, the model aims to determine the optimal inspection interval that minimizes the expected cost per unit time. The model applicability is validated through comparative experiment over some heuristic maintenance strategies.