A pulsed eddy current detection device and method based on frequency domain lift-off cross point

Abstract

The invention provides an impulse eddy current detection device and method based on frequency domain lift-off intersections and belongs to the field of electromagnetic nondestructive testing. An impulse eddy current thickness measuring method comprises specific steps as follows: firstly, differential signals of a standard sample under different lift-off distance and different conductivities are acquired by the impulse eddy current detection device; secondly, frequency domain real-part spectrum signals are obtained by Fourier transform, and the frequency domain lift-off intersections in the real-part spectrum are extracted; thirdly, thickness of the standard sample is changed, and the frequency domain lift-off intersections under different thicknesses and different conductivities are obtained; finally, amplitudes at the frequency domain lift-off intersections are extracted respectively, and a curve of the amplitudes changing with the thicknesses of the standard sample is obtained by fitting; when a tested piece with known conductivity and unknown thickness is subjected to the same transform treatment, obtained amplitudes at the frequency domain lift-off intersections of the unknowntested piece are substituted into the fitted curve, and thickness parameters of the tested piece can be obtained. The device and the method have the advantages as follows: the application of signal characteristics of the impulse eddy current lift-off intersections is expanded, and detection precision and reliability are improved.

Description

technical field [0001] The invention relates to the field of electromagnetic non-destructive testing, in particular to a pulsed eddy current testing device and method based on frequency-domain lift-off intersections. Background technique [0002] In the fields of aerospace, petrochemical and rail transportation, steel structures and aluminum alloy components are widely used to support loads or transport liquid media to reduce corrosion, improve strength and reduce component weight. Generally, structural components are coated with an insulating coating, and the load changes are relatively complex, which makes the pressure and supporting structures bear greater pressure and surface impact. At the same time, the environment will also bring strong corrosion and wear, resulting in structural components. Different degrees of corrosion lead to thinning of the wall thickness, seriously affecting the safety and quality of the component structure, and causing major safety accidents an...

AI Technical Summary

Problems solved by technology

[0005] The object of the present invention is to provide a pulsed eddy current detection device and method based on the frequency domain lift-off cross point, to solve the problem caused by the different thickness of the coating when the structural parts with coating coatings are inspected for corrosion and thinning. The problem of lift-off effect caused by the change of probe lift-off

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