Reliability analysis of PMS with failure mechanism accumulation rules and a hierarchical method

Phased-mission systems (PMSs) are featured by the variety of system configuration, environment or load condition in different phases which can attribute to the alteration of system behavior. From the view of failure mechanism development, the damage accumulation of each mechanism in different phases should be considered for calculating the system reliability. A hierarchical model based on the binary decision diagram (BDD) is proposed to integrate four types of damage accumulation rules into PMS reliability modeling, including the homogeneous failure mechanisms with phase constant stress or combinational profile and inhomogeneous failure mechanisms which have the same damage effect in one phase or different phases. An extended BDD was combined into the traditional BDD model to integrate three different levels of the failure accumulation, including the failure mechanism level, the phase level and the mission level. As a study case, the reliability of a phased-mission control and drive system was modeled and analyzed. Results showed that the proposed method can effectively describe the changing behavior of a PMS and obtain the system reliability by calculating the model.