Research On Ultrasonic Imaging Testing For The Thin-diameter Titanium Alloy Rod

Ultrasonic imaging testing for the Titanium alloy small diameter rod is adifficulty in ultrasonic nondestructive testing. Not only there is a blind spot in thedetection of small diameter rods, but also titanium coarse grain materials scatteringcaused excessive noise signal and other issues. TC11titanium alloy bars is the mainraw material for manufacture aircraft engine parts, Ultrasonic testing for the TC11titanium alloy rods is of great significance to ensure product quality.This paper using the combination of theoretical analysis, numerical simulationand experimental detection method to research flooding focused ultrasound imagingdetection method for the small diameter TC11titanium alloy rods. Firstly, This paperis from the angle of the matched filter signal processing to overview the basicprinciple of synthetic aperture focusing. On this basis, for the contradiction betweenthe resolution and signal-to-noise ratio in the actual defect detection is proposed tocarry out the synthetic aperture focus imaging algorithm which transformed in theFourier domain and based on correlation analysis of non-linear, and the actual processof this algorithm is given.Secondly, the project carried out the experimental study on ultrasonic syntheticaperture focus imaging detection for the small-diameter rod of titanium alloy TC11.Ultrasonic c-scan imaging device based on Physical Acoustics Corporation toestablish the experimental system, design and process a small diameter rod sample,manufacture reflected cross-hole and reflected flat bottom hole. The experimentalresults show that the application of the imaging method of the synthetic aperturefocusing imaging method in order to achieve optimal imaging results on the basis ofthe A-scan data in series, the advantages of this technique was that the small size ofthe probe unit and low frequency of the transducer can be obtained a high lateralresolution; Synthetic aperture focusing imaging technology handle the A-scan datathen could improve the lateral resolution of the image, the signal-to-noise ratio,sharpness enhancement; In addition, the synthetic aperture focusing is based on thesuperposition algorithm delay of the time-domain signal, the ultrasonic echo signalsand then transformed by Fourier change space for the frequency domain data,superimposed and then inverse Fourier transform; The Fourier reconstruction imagedata can be obtained two-dimensional image of a small diameter rods. Meanwhile, in consideration of the degree of correlation of the linear scanning signal factors,analyzed the correlation coefficient numerical size of the echo signals received byadjacent scan points, after correlation weighting processing data can be enhancedaround the defect at the amplitude level of the defect signal; The results obtained bythe pretreatment data and then delay superimposed which help eliminate the noise ofthe material itself and the level of clutter signals, the image has a certain degree ofoptimization.The research project of the small diameter rod provide a theoretical and methodbase of high-precision ultrasound automatic imaging detection and defect recognition,it has a certain value.