Sheet air coupled ultrasonic Lamb wave total-focusing imaging detection method

Abstract

The invention discloses a sheet air coupled ultrasonic Lamb wave total-focusing imaging detection method. Different from traditional ultrasonic array signal acquisition, only aiming at a single soundvelocity medium, propagation time of sound waves in air needs to be taken into consideration for acquisition of air coupled array signals. Therefore, the sound velocity ca in the air and the propagation speed cg of the Lamb wave in a plate are measured by using a standing wave method and a wave velocity method respectively. The acquired air coupled ultrasonic Lamb wave array signals exist in the form of a three-dimensional matrix Nti x Ntj x A, the acquired air coupled ultrasonic Lamb wave array signals are subjected to division of an imaging grid region, according to the arrangement positionof a probe, the defect position, and the sound wave propagation speed, the delay time of each scanning path is calculated, and delay superposition total-focusing imaging of the signals is realized according to a delay rule of the sound waves. According to the method, the high-quality ultrasonic total-focusing technology is expected to be expanded to the sheet air coupled ultrasonic Lamb wave imaging detection, so that the defect detection capability is effectively improved.

Description

technical field [0001] The invention relates to the field of ultrasonic non-destructive testing, in particular to a thin-plate air-coupled ultrasonic Lamb wave all-focus imaging detection method. Background technique [0002] As a new type of non-destructive testing technology, non-contact air-coupled ultrasonic testing makes up for the traditional ultrasonic testing due to its characteristics of no coupling agent, no secondary pollution of material components, and the ability to arrange sensors on one side for in-service testing. lack of. Furthermore, due to the characteristics of fast propagation speed, long propagation distance, and sensitivity to defects in laminates, combined with air-coupled ultrasonic testing technology, Lamb waves have become one of the most widely used detection methods for thin-plate components today, and have been recognized in China. Highly recognized by foreign research scholars. However, due to the use of air medium coupling, the acoustic imp...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a thin-plate air-coupled ultrasonic Lamb wave omni-focus imaging detection method to solve the problem of low Lamb wave echo signal resolution and signal-to-noise ratio in the existing detection technology. The present invention is based on the omni-focus The basic principle of imaging, improving the traditional total focusing method, making it suitable for imaging detection of thin plate air-coupled ultrasonic Lamb wave

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