Gas Path Fault Information Fusion Of Aero-enging Based On D-S Evidence Theory And FMECA

Aero-engine gas path structure is complex, and gas path fault in engine occupies a large proportion in the total failure. The gas path fault diagnosis is always company with complicated uncertain informations; the information fusion technology combined with engine fault diagnosis is a popular research in recent years. However, there’s no uniform method and model, so it remains to be further studied the problem.The reliability of aero-engine gas path system affects the reliability of the engine directly, and FMECA method is effective to improve system reliability. So in pneumatic system which is the research object, it is very necessary and meaningful to conduct FMECA analysis for the development of aeroengine.Aero-engine gas path system was used as our research object, and two aspects of research were carried out, including the aero-engine gas path fault information fusion research and aero-engine gas path FMECA analysis.In terms of aeroengine gas path fault information fusion, following work was carried out:(1)Research the D-S evidence theory comprehensively, including the theoretical basis, basic idea, advantages and disadvantages, synthetic rules and basic properties of the D-S evidence theory, and the D-S synthetic rules were completely mastered by an example.(2)With information fusion based on D-S evidence in fault diagnosis of aero-engine gas path, the effective basic framework and model of gas path fault fusion were established. Through an example of gas path fault diagnosis, the information of fault symptoms and decision level were fused respectively.(3)The failure information fusion problem was analysed when evidence conflict. Compard with all kinds of methods to solve the problem of conflict, a kind of effective method to solve the problem of conflict was focused on. On this basis, an effective fault information fusion frame of evidence conflict was established, and the correctness of the framework, rationality and reliability was illustrated by an example in which the gas path fault information fusion evidence is conflict.In terms of aeroengine gas path FMECA, following work was carried out:(1)Research the FMECA method system systematically, such as the purpose, methods, steps, and so on, and then, the block diagram of FMECA analysis steps was given. Then three kinds of calculation methods of RPN to the application of hazard analysis were emphasized.(2)Analyse the structure of turbofan engine comprehensively. As the research object, the structure and function of the parts in the gas circuit system were analysed in detail. The hierarchy relationship of aero-engine gas path system’s function and structure was established. Gas path system FMEA was analysed comprehensively in order to establish an effective gas path system FMEA table.(3)On the basis of expert scoring, three kinds of RPN calculation method for gas path system to quantify the harmfulness of failure mode analysis were used respectively, and the characteristics of the three methods were analysed and compared. The weak link of the engine gas path system was found through analysis and contrast, and a more effective FMECA table was concluded, as a result, the reliability of the gas circuit system was improved.In this paper, the information fusion based on D-S evidence theory was combined with an efficient gas path fault diagnosis, evidence theory was combined with FMECA effectively, effective theoretical models and methods were put forward and a useful FMECA report was summed up which provide the basis for improving the design of aircraft engine and make a contribute to this research area.