Ultrasonic TOFD dead zone inhibition method based on synthetic aperture focusing and mode converted wave

Abstract

The invention discloses an ultrasonic TOFD dead zone inhibition method based on synthetic aperture focusing and mode converted wave, and belongs to the technical field of the nondestructive detection. The method adopts a TOFD detection system composed of an ultrasonic flaw detector, a TOFD probe, an inclined organic glass wedge and a scanning device; the method comprises the following steps: implementing scanning and image collection along a surface of a to-be-tested workpiece, acquiring an A scanning signal set at different scanning locations; performing time delay and amplitude overlapping processing on all A scanning signals when solving the shortest propagation sound of the mode converted waves at various locations according to Fermat theorem, and realizing TOFD scanning image reconstruction through point-by-point focusing, weakening a lateral redundancy signal, and improving imaging quality. The end point depth of the defect in the dead zone range can be computed by utilizing the relevancy between the mode converted display depth and the defect end point depth in the reconstructed image. Compared with the existing mode converted wave method, the method can improve the defect quantitative precision when inhibiting the TOFD dead zone, and the method has high engineering application and popularization value.

Description

technical field [0001] The invention relates to an ultrasonic TOFD blind zone suppression method based on synthetic aperture focusing and mode conversion waves, which belongs to the technical field of nondestructive testing. Background technique [0002] TOFD (Time of Flight Diffraction, TOFD) is a non-destructive testing method that utilizes the time difference of longitudinal wave diffraction at the end of the defect to implement defect quantification. It has the advantages of high quantitative accuracy and high defect detection rate, and is widely used in petrochemical, electric power and Isotropic material detection in fields such as natural gas. However, when ultrasonic TOFD scanning is performed on near-surface defects, due to the certain width of the ultrasonic pulse, the diffraction wave signal at the end of the defect is easily lost in the through-wave, forming a near-surface detection blind area, and it is difficult to quantify the depth of defects in the blind are...

AI Technical Summary

Problems solved by technology

Its purpose is to solve the problem of horizontal redundant signals in the mode-converted wave in the defect scanning image in the TOFD blind zone, combine the synthetic aperture focusing technology to implement point-by-point focusing imaging on the mode-converted wave, and use the mode-converted wave in the reconstructed image to display the depth and defect The correlation of the end point depth realizes the accurate quantification of the defect end point depth in the TOFD blind zone

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