Reliability Calculation Model for Repairable Systems Considering Failure Correlation and Variable Hazard Rate

Considered the positive correlation existed in working life lengths of components and repair time lengths of the failure units belonged to the same repairable system based on Copula theories, and extended the distributions for working time lengths and repair time lengths of the components to the general continuous types, rather than confined to exponential distribution. Presented the concept of one step state transition matrix for repairable systems in minimal time difference t→t+△t, then turned out the state transition density matrix, by solving a system state equation, given availability at any time t and steady-state availability computing models for single-unit, series type, parallel repairable system consisting of two different units and a repairman respectively. A practical case calculation demonstrates the feasibility and effectiveness of the theory.