Availability Analysis for General Repairable Series and Parallel Systems with Repair Time Threshold

One of the most important topics in system reliability and performance measurements is availability analysis. In this paper, the availability of both series and parallel systems is addressed considering repair time threshold. A threshold is considered for the repair time, and if the repair time is less than the threshold, the system can be considered as working, and the repair time can be ignored. On the contrary, if the repair time is longer than the threshold, then the system is considered as not working from the beginning of the system failure until the repair time exceeds the threshold. Both constant and random repair time thresholds are considered. Also, to investigate the instantaneous availability of the series and parallel systems, both identical and non-identical components are incorporated. In addition, user-observed and perceived systems are incorporated and analyzed. Numerical analysis is conducted, and the results suggest an increase in the instantaneous and steady-state availability, especially in the series systems. Based on the results, neglecting repair time threshold can lead to a significant difference in the system’s availability, which can have a substantial impact on maintenance plans and company costs.