Application Of Acoustic Emission Technique In Diagnostics Of Rubbing Fault

Rubbing between the rotor and the stator is the frequent fault in the rotatingmachine, which has great harmfulness to the safe and stable running of the rotatingmachine. Thus, it is very significant to study the diagnosis method of the rubbingfault of the rotating machine. It has been proved that rubbing between the rotor andthe stator can produce abundant acoustic emission (AE) signal. Therefore, AEtechnique can be used to study the diagnosis method of the rubbing fault. And AEbased diagnosis method of the rubbing has obvious superiority compared with thevibration based one.This dissertation uses AE technique to perform theoretical and experimentalstudy of AE based diagnosis method of the rubbing fault. The main contents includethe following three aspects: 1. Parameter analysis of the rubbing AE. Classical AEparameters, such as rms, peak amplitude, rising time and AE counts, i.e., are used toanalyze the feature and the propagation characteristic of the rubbing AE. And thecorresponding identification methods for different kinds of AE are proposed. 2.Waveform analysis of the rubbing AE. The wavelet analysis, especially waveletscalogram and reassignment scalogram, is utilized to analyze the time-frequencycharacteristic and propagation characteristic of the rubbing AE. In this study, otherproblems, such as the choice of wavelet family and wavelet transform basedde-noising method, are discussed. In addition, energy percentage of the multi-scalesis calculated to obtain corresponding features of the different AE signals. 3.Cross-correlation based AE source locating method is discussed. Combingcross-correlation method with wavelet transform, wavelet modulus maxima andband-pass filter respectively to perform locating the rubbing AE source throughexperiment. The results are analyzed and compared. And corresponding applicationcondition of these three methods are concluded.