PROFUST RELIABILITY ANALYSIS OF FLY-BY-WIRE SYSTEM FOR AN ACT TEST AIRCRAFT

<正> Conventional reliability theory is based on binary-state assumption and probabilityassumption. However in many cases the binary-state assumption is not acceptable, i.e., thesystem failure cannot be reasonably defined in a crisp way but should be in a fuzzy way,and thus fuzzy-state assumption should be taken in place of the binary-state assumption.Profust reliability theory is a form of fuzzy reliability theory and based on the fuzzy-stateassumption and the probability assumption. Therefore profust reliability is a new reliabilityindex and can be used to comprehensively characterize system reliability behavior. Failuresof the longitudinal fly-by-wire system in an ACT test aircraft are divided into threeclasses: safety-fatal, task-fatal and maintenance-required, and profust reliability analysisfor this system is performed. Further, a new index of failure criticality on top of profustunreliability is defined so that this new index is not only adequate to reasonably distinguisheffects of distinct failure modes, but also able to directly account for the effects of failuremodes on system reliability behavior. The conclusion of this paper is that it is reasonable totake the profust reliability as the system design index.