A Thick-Walled Structure Defect Detection Method Based on Oblique Incident Ultrasonic Synthetic Aperture Focusing

Abstract

The invention discloses an oblique incident ultrasonic synthetic aperture focusing-based thick wall structure defect detection method, and belongs to the technical field of nondestructive detection. The method comprises the following steps: a thick wall structure test block is detected through using a phased array electron scanning function by using an ultrasonic detection system comprising a phased array ultrasonic flaw detector, a phased array ultrasonic probe and an oblique organic glass wedge in order to obtain the A scanning signal set of all phased array elements; the Fermat's theorem is used to solve the emission point positions of all the phased array elements and image reconstruction points in the wedge / test block interface, and all A scanning signals undergo time delaying and amplitude superposing processing; and the processed A scanning signals undergo Hilbert transformation, and a difference function is used to obtain a reconstructed ultrasonic detection B scanning image. The method has the advantages of high defect detection resolution, large detection range, detection efficiency increase, and provision of an effective solving technology for the nondestructive detection problem of the defect of a thick wall structure. The method also can be embedded to the flaw detector to realize automatic real-time imaging, and has high engineering application values.

Description

technical field [0001] The invention relates to a thick-walled structural defect detection method based on oblique incident ultrasonic synthetic aperture focusing, which belongs to the technical field of nondestructive testing. Background technique [0002] Thick-walled structures are widely used in many industries such as nuclear power, petroleum, chemical industry, and electric power. For example, the main pipes of nuclear engineering are mostly thick-walled structures with a thickness of more than 60mm. These structures are often exposed to harsh service environments such as high temperature, high pressure, high radiation, and strong corrosion for a long time, and are prone to defects, making their safety performance attract much attention. Ultrasonic testing technology has been applied to non-destructive testing of thick-walled structural defects due to its simple principle, intuitive test results, environmental protection and safety. However, the ultrasonic sound beam ...

AI Technical Summary

Problems solved by technology

Its purpose is to solve the problem that the energy attenuation of conventional ultrasonic testing is large in thick-walled structures, and it is difficult to realize large-scale, high-resolution scanning at one time. The phased array electronic scanning function is used to obtain oblique incidence ultrasonic waves with tilted plexiglass wedges. Signal, based on Fermat's theorem and SAFT principle, time delay and amplitude superposition processing are performed on the signal, and then a large-scale, high-resolution ultrasonic detection B-scan image is obtained

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