Reliability evaluation of phased mission system under multiple correlated failure modes

Many large complex equipment, such as spacecraft and satellite, are typical Phased Mission Systems (PMSs). Due to sophisticated structure and complex missions, the components and systems of PMS have multiple failure modes which are correlated. On the one hand, taking multiple correlated failure modes in to consideration can describe the multistate characteristics of the system more accurately and decouple the correlation between different phases of the system more clearly. On the other hand, its complexity makes the reliability evaluation of PMS more difficult. To solve this problem, this paper discusses the modeling method of multiple failure modes and their correlation, proposes an improved combination method of Multiple Failure Mode Tree (MFMT) and Multistate and Multivalued Decision Diagram (MMDD) model, and realizes the reliability evaluation of PMS in cross-level (failure mode-component-system) and cross-scale (single phase-multiple phases). Finally, the proposed method is applied to evaluate the reliability of the satellite attitude orbit control system (AOCS) in order to verify its feasibility.