A defect identification and classification method based on multi-frequency eddy current testing technology
An eddy current detection and defect identification technology, which is used in measurement devices, material analysis, material analysis by electromagnetic means, etc., can solve problems such as unsatisfactory internal defect detection results, difficulty in identifying and classifying different defects, and insignificant defect classification effects. , to achieve the effect of wide application, simple process and suppression of lift-off noise
Active Publication Date: 2022-04-05
TIANJIN POLYTECHNIC UNIV
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Problems solved by technology
Due to the skin effect of the inspected workpiece of the conductor material in the electromagnetic eddy current inspection process, the detection effect of the lower surface defect and internal defect of the inspected workpiece of the conductor material is not ideal, so the traditional eddy current inspection method of measuring the coil impedance is difficult to identify and classify different defects
[0003] Aiming at the problems existing in the above eddy current testing technology, the current corresponding solution is to use pulsed eddy current testing technology to identify and classify defects by using the peak time of the transient response signal of the detection signal, zero-crossing time, and spectral separation points as feature quantities, but These methods are more or less difficult to extract feature quantities, and the effect of defect classification is not obvious.
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[0035] A defect identification and classification method based on multi-frequency eddy current detection technology of the present invention will be described below in conjunction with the accompanying drawings and the detection embodiments of aluminum plate surface defects, lower surface defects, and internal defects.
[0036] Such as figure 1 As shown, the multi-frequency eddy current detection system includes a function generator, a linear DC regulated power supply, a V / I conversion circuit, a double air core coil sensor, a signal amplification circuit, an acquisition card, and a computer. The computer-controlled function generator provides a sinusoidal excitation signal to the sensor through the V / I conversion circuit, and at the same time controls the scanning platform equipped with the sensor to perform frequency sweep scanning along the scanning path above the aluminum plate. The signal collected by the sensor is amplified by the signal amplification circuit. The acquis...
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The invention discloses a defect identification and classification method based on multi-frequency eddy current detection technology, which includes using multi-frequency eddy current detection technology to detect the inspected workpiece to obtain a detection signal; and then using phase-sensitive demodulation technology to obtain phase angle change information of the detection signal ;Solve the phase angle gradient in the direction of scanning frequency and scanning position; finally analyze the changing trend of phase angle gradient in the direction of scanning frequency and scanning position to identify and classify defects. The beneficial effect of the invention is that the identification and classification of surface defects, subsurface defects and internal defects can be realized quickly and accurately, and the phase angle gradient can effectively suppress lift-off noise as a feature quantity, and has a certain market application prospect.
Description
technical field [0001] The invention relates to the field of electromagnetic nondestructive testing, in particular to a defect identification and classification method based on multi-frequency eddy current testing technology. Background technique [0002] In the process of electromagnetic eddy current testing, the defect of the inspected workpiece of conductor material is mainly detected by measuring the change of coil impedance. The impedance (or induced voltage) of the detection coil has many interference factors, among which the change of the lift-off height (the lift-off height refers to the vertical distance between the sensor and the surface of the workpiece under inspection) has a particularly obvious impact on the detection effect. Due to the skin effect of the inspected workpiece of the conductor material in the electromagnetic eddy current inspection process, the detection effect of the lower surface defect and internal defect of the inspected workpiece of the cond...
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IPC IPC(8): G01N27/9013
CPCG01N27/9013G01N27/9046
Inventor 张荣华叶松宋观惠李洁
Owner TIANJIN POLYTECHNIC UNIV