Condition-based optimization of non-identical inspection intervals for a k-out-of-n load sharing system with hybrid mixed redundancy strategy

Abstract

This paper aims to minimize the expected daily inspection cost of a k-out-of-n load-sharing system with identical components. We consider a hybrid mixed-redundancy strategy for the components’ utilization at the beginning of each inspection interval when failed components are replaced by standbys using an imperfect switch. The number of active components at the beginning of inspection intervals as well as the duration of inspection intervals are varying, and depend on the number of available components. The components are assumed identical with a constant failure rate, which implies the components’ distribution function is exponential. We optimize both the number of active components at the beginning of each interval and the duration of the inspection intervals to minimize the system’s expected daily cost (SEDC). The SEDC has four components: the system’s inspection cost, the components’ repair cost, the system’s repair cost, and the system’s downtime cost. A new heuristic algorithm is used to optimize the model. Due to the model’s complexity, a genetic algorithm is suggested for large-size problems. The results show the model decreases the SEDC by a maximum of 64.89% compared to other existing strategies with fixed inspection intervals.