More Research Status, Multi-stage Tasks System Reliability Analysis Method

With the progress of science and technology, the major equipment continuesmelting towards maximization and complication, and the reliability analysis of majorequipment becomes more and more complex. Major equipment, such as aero-engine,nuclear reactor power control system and space station, which may lead large economiclosses and human causalities once failed during the operation. Therefore, it is necessaryto make full use of reliability engineering technology to improve the reliability of themajor equipment. It finds that the major equipment often having multi-state andphased-mission characteristics, so carrying out research study in multistate systems andphased-mission systems is particularly important.The main contents of this thesis are as follows:(1) Reliability evaluation of multi-state systems with imperfect fault coverage andcommon cause failuresThe imperfect fault coverage introduces multimode failures that must beconsidered in the accurate reliability analysis of multi-state systems. Another difficult inanalysis is common cause failures that can effect different subjects of systemcomponents, and which can occur s-dependently. Our methodology for resolving theabove difficulties is to separate the consideration of both IPC and CCF. According to theseparation order, two equivalent approaches are developed. The applications andadvantages of the approaches are illustrated through examples.(2) Reliability analysis of phased-mission systems with imperfect fault coverageand common cause failuresSimilar as (1), reliability analysis of phased-mission systems with IPC and CCFalso suffer the above two difficulties, to overcome the challenges, we proposed twoequivalent methods for the analysis of PMS with both IPC and CCF.(3) Reliability analysis of multi-state systems with propagated failures and failureisolation effectThis thesis considers the reliability analysis of multi-state systems subject topropagated failure with global effect (PFGE) and failure isolation effect. The PFGE can be caused by an imperfect fault coverage despite the presence of fault-tolerantmechanism or by a destructive effect of failures that originate from some systemcomponents on other components. The failure isolation effect is caused by functionaldependence among system components, where the failure of some component canprevent the propagation of failures that originate from other components within thesame system. In this thesis, a separable and combinatorial method has been proposed,and an example is analyzed to demonstrate the application and advantages of theproposed method.