Towards an Efficient and Robust Maintenance Decision-Making

In the literature, the effectiveness of a maintenance strategy is usually assessed through a cost criterion which is the long-run expected maintenance cost rate (i.e., performance viewpoint). However, such a criterion does not allow evaluating the variability of maintenance costs from a renewal cycle to another, and classical maintenance strategies seem inappropriate in the sense of risk management (i.e., robustness viewpoint). Therefore, this paper aims at (i) re-evaluating classical strategies from both performance and robustness aspects, and hence (ii) suggesting more suitable maintenance decisions. Especially, by defining the long-run expected maintenance cost rate as the performance criterion and the variance of maintenance cost per renewal cycle as the robustness criterion, we consider two representatives of time-based and condition-based maintenance families: a block replacement strategy, and a periodic inspection and replacement strategy. Their mathematical cost models are developed on the basis of the homogeneous Gamma degradation process and the theory of probability. The comparison results of both maintenance strategies show that the strategy which has a higher performance incurs a higher level of risk. So, it is necessary to assess jointly the performance and the robustness of maintenance strategies to find out a more reliable decision.