Application And Research Of FTA And Fuzzy Theory In Mechanical Fault Diagnosis

The FTA is the one that is more fit for the complicated system. In This thesis,combining the FTA with the fuzzy theory,the uncertainty problem that cannot be solved with the traditional FTA in the mechanical fault diagnosis,the multi-fault phenomenon that faults take place in complex system and the intersectional relation between fault omens and fault reasons is solved. The basic trait and step of the FTA and the fuzzy fault tree analysis are introduced,especially the basic theory of the qualitative analysis and the quantitative analysis. In the aspect of the selection of fuzzy probability of bottom event,the concept of the basic condition in the priority of selecting the fuzzy number model is brought forward,and traits of the fuzzy number model is analyzed and compared. The reason that the accurate probability is replaced with the probability of linear fuzzy number is elucidated. And the definition and arithmetic of the logic gate fuzzy arithmetic operators is established. Combining the Fuzzy Decision-making theory with the analysis method of the interested degree in fault tree analysis,the ideas of ensuring the membership degree with the interested degree and establishing fuzzy matrix is put forward,and is testified with the stringent mathematic theory. Therefore the efficiency and quantity of fuzzy matrix establishment is improved,and further the field of application of fault tree analysis is developed. Based on the fault tree analysis theory,the CAFTA is manufactured,and fault tree that is out of order in braking system is analyzed. The result is preferable.