A condition-based maintenance policy for continuously monitored multi-component systems with economic and stochastic dependence

In this paper we propose a condition-based maintenance policy for continuously monitored multi-component systems subject to stochastic dependence through load sharing and economic dependence through maintenance set-up costs. Stochastic dependence provides an incentive to replace failed components as soon as possible, since component failures increase the load, and hence the deterioration rates, of the remaining components. In contrast, economic dependence encourages the clustering of component replacements to reduce maintenance frequency, resulting in less downtime and fewer maintenance set-up costs. In this paper, we propose a novel, condition-based maintenance policy to obtain the optimal replacement decisions at maintenance opportunities. Through numerical studies we see the importance of a policy that incorporates both types of system dependence. The policy incorporates a utility/reward function that is a combination of interpretable penalties that encapsulate the costs of stochastic and economic dependence. The utility function trades off the rewards of clustering components with the loss due to load sharing. The policy minimizes the overall cost of the system by choosing actions that minimize the total long-term penalty. We show that the proposed policy outperforms various alternative policies by reducing system life-cycle costs.