Maintenance strategy selection for multi-component systems using a combined analytic network process and cost-risk criticality model

Selection of an appropriate maintenance strategy for multi-component systems is a very complex task due to diversity of components and their different failure modes, existence of various dependencies among components, and a large number of competing criteria that need to be taken into consideration. In this study, we propose a combined analytic network process (ANP) and cost-risk criticality analysis model to select a cost-effective, low-risk maintenance strategy for different sets of components associated with the system. The proposed model consists of four maintenance alternatives (i.e., failure-based, time-based, risk-based, and condition-based) among which the most appropriate strategy, on the basis of two criteria of maintenance implementation costs and failure criticality, is to be chosen. The former criterion includes the annual maintenance expenditure required for hardware, software, and personnel training, while the latter focuses on the capability of maintenance in mitigating the failure vulnerability and enhancing the reliability and resilience. The possible dependencies among selection criteria as well as the failure interactions between components are taken into account in evaluating the maintenance alternatives. Finally, the model is applied to determine a suitable maintenance strategy at the design stage for a new wind turbine configuration consisting of several mechanical, electrical and auxiliary components. The results are then compared to the operational practices of maintenance and to the results obtained using an analytic hierarchy process (AHP) model.