Defect identification and evaluation method of metallic conductor based on giant magnetoresistance sensor

Abstract

The invention belongs to the technical field of nondestructive test, and relates to a defect identification and evaluation method of a metallic conductor based on a giant magnetoresistance sensor. A detection probe adopted by the method comprises an exciting coil, the giant magnetoresistance sensor and a permanent magnet, wherein the giant magnetoresistance sensor is fixed at the bottom of the exciting coil; and the permanent magnet is fixed at the outer side of the exciting coil. The method comprises the steps of placing the detection probe at the surface of a tested piece; exerting a sine signal on the exciting coil; moving the detection probe to scan the tested piece; demodulating an output signal of the giant magnetoresistance sensor to obtain amplitude and phase angle information; recording the position of the detection probe in the scanning process; respectively drawing a curve of the amplitude changing along with the position of the probe and a curve of the phase angle changing along with the position of the probe; judging that whether a defect exists at the scanning position; and evaluating the position and the size of the defect. The defect identification and evaluation method of the metallic conductor has the advantages of being easy to operate, high in response speed, good in instantaneity, accurate in judging and evaluating at the same time, easy to carry out and the like.

Description

Technical field [0001] The invention belongs to the technical field of nondestructive testing, and relates to an eddy current defect identification and estimation method. Background technique [0002] Eddy current non-destructive testing is a non-destructive testing technology based on the principle of electromagnetic induction. It has the advantages of no coupling agent, non-contact measurement, easy automatic measurement, simple process, easy operation and fast detection speed. It is used in the non-destructive testing of conductive materials. It has broad application prospects. [0003] Traditional eddy current testing usually uses a coil as a detection probe, the sensitivity is proportional to the frequency, and the detection depth and detection range are limited. The giant magnetoresistance (Giant Magneto Resistance) sensor greatly increases the scope of application of eddy current detection because its detection sensitivity is not affected by the excitation frequency....

AI Technical Summary

Problems solved by technology

This method overcomes the shortcomings of only using the defect signal amplitude for defect judgment, introduces the phase angle as the object of defect judgment, and provides a method for defect location and estimation, which reduces the possibility of missed detection and false detection

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