Flaw sizing method for rod workpieces based on deconvolution of ultrasonic C-scan image
Flaw sizing is the focus of research in the flied of non-destructive testing.The diffusion of ultrasonic waves will cause edge blur of C-scan images,which affects the accuracy of flaw sizing.Based on the multi-Gaussian beam model,according to the propagation law of the ultrasonic wave at a curved interface,the point spread function(PSF)of the rod water-immersion ultrasonic imaging system is deduced.The nylon rod with flat-bottomed holes is scanned by a four-axis ultrasonic water-immersion testing system to obtain the C-scan image,and then the C-scan image is deconvoluted with the Richardson-Lucy iterative algorithm.The 6 dB drop technique is used to quantitatively analyze the original image and the deconvoluted image.The results indicate that the proposed deconvolution method exhibits a higher sizing accuracy.In particular,the error of the 1.5 mm diameter flat-bottom hole is reduced from 88%to 18.7%.
point spread functionmulti-Gaussian beam modelRichardson-Lucy(RL)iterative algorithmrod workpiece
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