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Modulation multifrequency eddy current testing method

An eddy current detection and eddy current sensor technology, applied in the direction of material magnetic variables, etc., can solve the problem of long detection time, reduce the detection time, improve the detection speed of defects, and reduce the peak factor.

Inactive Publication Date: 2014-04-16
NAT UNIV OF DEFENSE TECH
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Problems solved by technology

[0006] In the multi-frequency eddy current detection method of the asynchronous synthesis excitation method, the excitation signal uses sinusoidal signals of multiple frequency components to drive the eddy current sensor in turn, and the frequency of the excitation signal needs to be switched continuously, and the detection time is long

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[0038] The working process of the modulated multi-frequency eddy current detection method of the present invention is as follows: image 3 shown.

[0039] see below Figure 3 to Figure 11 , taking the defect detection and classification of aluminum flat panels as an example to specifically illustrate the working process of the modulated multi-frequency eddy current detection method of the present invention:

[0040] The first step, prepare reference test piece, this reference test piece is the test piece without defect: in the present embodiment, if Figure 4 As shown, the reference test piece adopts a defect-free aluminum plate 1 with a size of 200mm×200mm×2mm.

[0041] In the second step, a frequency modulation excitation signal is generated, and after the frequency modulation excitation signal is amplified, the eddy current sensor is driven to detect the reference specimen: in this embodiment, what the frequency modulation excitation signal adopts is the linear frequency ...

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Abstract

The invention relates to a modulation multifrequency eddy current testing method, comprising the following steps: generate a frequency modulation excitation signal, amplify the frequency modulation excitation signal, drive an eddy current sensor, and respectively test a benchmark testing piece and an object to be tested; collect response signals of the eddy current sensor when testing the benchmark testing piece and the object to be tested, perform an FFT (Fast Fourier Transformation) transformation to the response signals of the eddy current sensor to obtain a frequency spectrum of the response signals of the eddy current sensor, and then analyze the frequency spectrum of the response signals of the eddy current sensor and respectively calculate total spectrogram energy, spectrogram center-of-gravity shift, spectrogram kurtosis and spectrogram skewness of each frequency spectrum of the response signals of the eddy current sensor; finally, perform threshold value judgment to the total spectrogram energy, spectrogram center-of-gravity shift, spectrogram kurtosis and spectrogram skewness of the frequency spectrum of the response signals of the eddy current sensor of the object to be tested and the frequency spectrum of the response signals of the eddy current sensor of the benchmark testing piece to judge whether the object to be tested has defects and the defect location or other parameters or not. The modulation multifrequency eddy current testing method can effectively reduce peak factors of the excitation signal and the response signal of an eddy current testing system and increase the testing speed.

Description

technical field [0001] The invention relates to a multi-frequency eddy current detection method adopted in the field of non-destructive testing, in particular to a modulated multi-frequency eddy current detection method, which is suitable for interference suppression in the detection process or multi-parameter detection of a detected object. Background technique [0002] Eddy current testing technology plays an important role in nuclear power plant steam pipe maintenance, aerospace equipment maintenance, pipe, wire, bar production and other industries. Eddy current testing technology has been widely used due to its advantages of non-contact, easy automation and strong detection ability. Applications. [0003] The conventional eddy current detection method uses a single frequency sinusoidal signal to excite the eddy current sensor, and the amount of information obtained is limited, which makes it difficult to meet the increasing demand for nondestructive testing. In 1970, Am...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N27/90
Inventor 高军哲潘孟春罗飞路翁飞兵何赟泽刘波
Owner NAT UNIV OF DEFENSE TECH
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