Longitudinal wave type electromagnetic ultrasonic probe and detection method

Abstract

The invention discloses a longitudinal wave type electromagnetic ultrasonic probe and a detection method, the probe is composed of a plurality of rectangular magnet sets with same magnetic poles arranged face to face, excitation and detection signal coils, signal connecting lines and a probe shell for fixing the magnet sets, the coil conductor part is located under the magnet, and the coil gap directly faces the magnet gap. The electromagnetic ultrasonic probe is directly close to the surface of a detected test piece, magnetic lines of force are emitted by N poles of two magnets which are arranged face to face, penetrate through a gap between the two magnets and return to S poles of the two adjacent magnets, and high-strength horizontal bias magnetic fields which are alternately arranged left and right are formed under the magnets; eddy currents which are alternately arranged front and back are sensed on the near surface of the detected test piece and interact with the horizontal magnetic field to form Lorentz force which is perpendicular to the surface of the detected test piece and is in the same direction, and therefore efficient excitation and receiving of ultrasonic longitudinal waves are achieved in the detected test piece.

Description

technical field [0001] The invention relates to a non-contact ultrasonic detection technology, in particular to a novel longitudinal wave electromagnetic ultrasonic probe and a detection method, which are easy to excite and receive ultrasonic longitudinal waves in non-ferromagnetic materials. Background technique [0002] Since the excitation and reception of longitudinal waves in body waves are mostly generated by traditional piezoelectric ultrasound. The advantages of traditional piezoelectric ultrasound are wide frequency band, high sensitivity, high signal-to-noise ratio, simple structure, reliable operation, and light weight. The disadvantages are the need for couplant and some piezoelectric materials require moisture-proof measures, and the output DC response is poor. The electromagnetic ultrasonic (EMAT) non-destructive testing technology has the characteristics of flexible generation of various waveforms, low requirements for the surface quality of the test workpiece...

AI Technical Summary

Problems solved by technology

Therefore, it is very necessary to develop a new type of longitudinal wave electromagnetic ultrasonic sensor. The longitudinal wave electromagnetic ultrasonic probe provided by the present invention overcomes the problem that the traditional electromagnetic ultrasonic probe is mainly used for transverse wave detection, and the longitudinal wave is difficult to excite and receive.

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