Research On Acoustic Emission Source Localization Technology Based On Time Difference Method

Acoustic Emission(AE)detection technology is a non-destructive testing technology,which can monitor the AE signals generated by various faults in the measured parts in real time,so as to realize real-time monitoring and prediction of the health status of the measured parts.Rub-impact is one of the common faults of rotating machinery,and the rub-impact is very harmful to rotating machinery.Therefore,real-time monitoring of this fault is necessary.AE source positioning technology is a key part of AE detection technology.The principle is to calculate the location and status of the fault point through the information contained in the signal collected by the sensor.In the positioning of rub-impact acoustic emission sources in complex rotating machinery systems,it is difficult for the conventional General Cross Correlation(GCC)delay estimation algorithm to obtain accurate delay values,and thus cannot accurately locate the acoustic emission sources.In order to solve this problem,this thesis starts from the basic theory of acoustic emission detection technology,and combines Cross Correlation(CC)algorithm,quadratic crosscorrelation algorithm,GCC delay estimation algorithm,Hilbert difference method and AE source localization algorithm.A double-weighted quadratic cross-correlation delay estimation algorithm based on Smoothed Coherence Transform(SCOT)is proposed to calculate the arrival time difference of AE source signal.Then,the Hilbert difference method is used to sharpen the relevant peaks,reduce the noise interference during the collision process,and obtain more accurate delay estimation results.Finally,the obtained delay value is used for AE source positioning.The experimental results show that compared with the conventional GCC algorithm,the algorithm has high positioning accuracy in the positioning of rub-impact sources in complex rotating machinery systems.