Lifetime Prediction and Spares Quantity Optimization for Non-Similar Standby Systems Based on Spares Failure

A standby system is a vital means to extend system operational time, and enhance fault tolerance and reliability. Modern industrial processes are complex and coupled, requiring the design of standby systems with different types of operating components in series or parallel to achieve specific functions. This paper addresses the scenario where spare parts experience random performance degradation during storage, focusing on non-similar standby systems. It establishes degradation models for various types of operating components and spare parts, deriving the life probability density functions (PDFs) for different standby subsystems. By leveraging the logical relationships among the standby subsystems, the paper derives the life formula for the non-similar standby system. Furthermore, with the operational time of the non-similar standby system as the objective function, the paper constructs an optimization function to determine the optimal inventory quantities for different types of spare parts within a given budget.