Study On The Signal Processing Technology For Ultrasonic Testing Of The Liner Grain Debonding Based On EMD

The interface debonding is generally detected by ultrasonic testing, which causesthe inconsistency of the noise and collected signals during the automatically detectingprocess. Aimed at this issue, the article takes the automatic ultrasonic testing signal asthe object, researches the extractive method of debonded signal through cross correlationtechnology and EMD method, and explores debonding-imaging processing technologythrough BEMD method, providing a foundation for the precise location and the areameasuring of debonding area.At first, the article discussed the immersive pulse-echo automatic ultrasonictesting processing of liner/propellant. By analyzing the unusual disturbance of echosignal and the inconsistency of debonding ultrasonic testing images, it provides aproposal about cross correlation technology combining EMD to extract the characteristicof debonded signals and combining BEMD to process ultrasonic imaging.Second, aimed at the feature of liner/propellant of ultrasonic-testing echo, itadopts cross correlation technology to revise the echo position of water/liner interface.Based on the foundation of traditional one-dimensional EMD method, combining thethreshold denoise technology of wavelet analysis, the article chooses proper threshold todenoise IMF by comparing the result of different threshold denoising echo signal, whichcan keep the characteristically debonded signal and eliminate the disturbing noise.Through analysis, the ultrasonic testing images are obviously better than the originalimages, showing the debonded area.Third, on the basis of collecting echo signal feature, the article respectively usesthe mean filtering, wiener filtering, and median filtering about debonding-ultrasonictesting images, and adopts iterate-selecting-threshold method to make a binarization onthe images after filtering. However, the information of debonded region is not ideal.Therefore, on the basis of the BEMD calculating process, through five-level decomposing and information-rebuild, it decreases the noise in the testing process andthe inconsistency of area.At last, the article also adopts iterate-selecting-threshold method to make abinarization on debonding-ultrasonic testing images after BEMD decomposing andrebuilding. After comparing these results with the traditional filtering binarizationimages, it shows that the method of the article has more effective result, which canproperly gain the debonded area and calculate the area.