Reliability analysis of phased mission system with non-exponential and partially repairable components

Phased mission systems (PMSs) have wide applications in engineering practices, especially in aerospace industry such as man-made satellite and spacecraft. To achieve high reliability in a PMS, certain critical parts in the system are designed to have a redundant architecture, such as cold standby (structural or functional). State-space models such as Markov processes have been widely used in previous studies to evaluate the reliabilities of these systems. But in practice, many real systems consist of mechanical components or mechatronics whose lifetime follow non-exponential distributions like the Weibull distribution. In this type of system, the Markov process is not capable of modeling the system behavior. In this paper, the SMP (Semi-Markov Process) is applied to solve the problem that the components' lifetime in dynamic systems follows non-exponential distributions. An approximation algorithm for the SMP is proposed to assess the reliability of the PMSs consisting of non-exponential components. Furthermore, the accuracy and calculation efficiency of the approximation algorithm are explored. At last, the reliability assessment of a complex multi-phased altitude and orbit control system (AOCS) in a man-made satellite is presented to illustrate the method.