Optimal inspection for systems with protective auxiliary component in dynamic environments

Abstract

For multi-component systems, components can be classified according to the impact of component failures: failures of the main component cause the system failures, while failures of the auxiliary component cannot be directly detectable and may put the system at some risk. In this paper, we study a system equipped with main and auxiliary components, and what differs this paper from previous studies on maintenance strategies for such systems is that, we consider not only the failure dependence between components due to the protective effect of the auxiliary component, but also the complex scenario where the system operates in dynamically evolving environments. Environmental evolution results in variations of failure rates of the auxiliary component and some dynamic negative impacts on degradation of the main component. Since hidden auxiliary component failures can only be found by inspection, we consider periodic inspection and opportunistic inspection of the auxiliary component in developing the maintenance strategy. Then we model the system operation by using a semi-regenerative process to obtain the long-run average cost, and minimize the longrun average cost using the inspection period τ as an optimizable decision variable.