Electromagnetic ultrasonic signal superposition method

Abstract

The invention discloses an electromagnetic ultrasonic signal superposition method which comprises the following steps: sequentially providing pulse voltage strings with the same pulse width for multiple transmitting coils according to the scheduled time interval so as to generate multiple ultrasonic wave signals; receiving the echo signals of the multiple ultrasonic waves through multiple receiving coils; carrying out the phase shift on multiple voltage signals corresponding to the multiple received echo signals, thereby enabling the phases of the multiple voltage signals to be same; and superposing the multiple voltage signals subjected to phase shift. According to the electromagnetic ultrasonic flaw detection method provided by the invention, the echo signals of the ultrasonic waves which have the scheduled phase difference are subjected to phase shift and superposition; the echo signals are received by the multiple receiving coils; and the signal amplitude is increased, thereby improving the single to noise ratio.

Description

technical field [0001] The invention relates to an electromagnetic ultrasonic flaw detection method, more specifically, an electromagnetic ultrasonic flaw detection method based on signal superposition. Background technique [0002] Electromagnetic ultrasonic testing is a new ultrasonic testing technology. Place the excitation coil (transmitting coil) with high-frequency pulse current on the conductive metal surface of the measured object, and the alternating magnetic field generated by the coil acts on the surface layer of the measured object to induce eddy currents with the same frequency and opposite directions. The eddy current is generated by the moving charged particle, and the eddy current interacts with a constant magnetic field (such as a permanent magnet or a DC electromagnet) applied to another part of the measured object at the same time. When flowing in the magnetic field, it is displaced by the Lorentz force, which is perpendicular to the direction of the magn...

AI Technical Summary

Problems solved by technology

However, the acoustic-electric conversion efficiency of electromagnetic ultrasonic waves is low, resulting in weak ultrasonic signals transmitted and received, and the signal-to-noise ratio of flaw detection is low in occasions requiring high detection sensitivity or long-distance guided wave detection

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