Abstract: According to the maintenance features of long-term storage products， the transient storage availability models for two typical kinds of components are established, respectively. A kind of component is inspected periodically. A failure may be missed by inspections with a fixed probability, and as soon as the failure is found, the component is repaired to as good as new condition after a period of time. The other kind of component is preventively replaced periodically, and the length of its replacement cycle is an integral multiple of that of the inspection cycle. Subsequently, the transient and average storage availabilities of the system which is composed of these two kinds of components are deduced, and a maintenance cost model for such a storage system is established. The inspection cycle length and replacement cycle length are optimized comprehensively for minimizing the average maintenance cost rate in a fixed storage period. The computed results indicate that the combination of these two variables has a large effect on the cost rate. A conclusion can be drawn that a reasonable schedule of maintenance cycle contributes to the reduction in the maintenance cost for a long-term storage system.

Key words: system engineering methodology, storage availability, cost analysis, repairable system, periodic inspection, periodic replacement