A multi-frequency excitation field array electromagnetic non-destructive detection method for metal surface cracks

A non-destructive testing, metal surface technology, applied in the direction of material magnetic variables, etc., can solve the problems of detection sensitivity of randomly distributed crack defects, single amplitude and frequency excitation source, etc., to achieve strong use value and improve reliability.

Active Publication Date: 2022-05-20
NORTHEASTERN UNIV LIAONING
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Problems solved by technology

[0004] The known techniques for detecting crack defects using alternating magnetic fields mostly rely on a single amplitude and frequency excitation source, which has a good effect on detecting the length and depth of crack defects, but the change of excitation frequency is very important for the detection of randomly distributed cracks. Defect Sensitivity Not Mentioned

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  • A multi-frequency excitation field array electromagnetic non-destructive detection method for metal surface cracks
  • A multi-frequency excitation field array electromagnetic non-destructive detection method for metal surface cracks
  • A multi-frequency excitation field array electromagnetic non-destructive detection method for metal surface cracks

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Embodiment

[0036] In this embodiment, the test piece is made of commonly used low-carbon steel Q235 steel, with a length of 160 mm, a width of 64 mm, and a thickness of 10 mm.

[0037] In this embodiment, the excitation device such asfigure 1 As shown, it consists of a U-shaped yoke and a square excitation coil wound in the middle. The excitation coil is made of enameled wire with a wire diameter of 0.6mm. The inner length of the coil is 20mm, and the outer length of the coil is 32mm. The effective length The U-shaped yoke is made of No. 10 steel, and its relative magnetic permeability is 10000. The outer size is 100mm*20mm*35mm, and the inner size is 80mm*20mm*15mm.

[0038] In this embodiment, the excitation signal in the excitation coil is as figure 2 As shown, it is formed by superposition of 2kHz, 5kHz and 10kHz sinusoidal currents whose amplitudes are all 0.5a, and the excitation period of the multi-frequency signal is 0.5ms.

[0039] A multi-frequency excitation field array elec...

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Abstract

A multi-frequency excitation field array electromagnetic non-destructive detection method for metal surface cracks, the method: 1) generate a standard defect at the center of the test piece; 2) connect the excitation device with the test piece to build a detection model; 3) The component is collected while the coil is excited, the detection signal of each data is extracted, and the EMD is used for empirical mode decomposition to obtain the intrinsic mode function signal; 4) According to the characteristics of the component data, the angle and axial direction of the crack defect are realized Accurate identification of length, circumferential length and radial length, and then convert the actual size of the defect; the invention uses a U-shaped yoke wound with a energized rectangular coil to excite the leakage magnetic field of the defect to realize the magnetic field disturbance above the defect. Signal collection, detection and identification of metal surface defects, improve the reliability of detection results, and have strong use value for electromagnetic nondestructive testing of specimens with complex defect shapes.

Description

technical field [0001] The invention belongs to the technical field of electromagnetic nondestructive detection of metal damage, and in particular relates to a method for electromagnetic nondestructive detection of metal surface cracks by a multi-frequency excitation field array. Background technique [0002] The scope of my country's oil development has moved towards seabed resources, and the number of my country's offshore oil exploration platforms along the coast continues to increase. These platforms are subject to routine safety hazard inspections every year. Under normal circumstances, the inspections are subsea steel frames and pipelines. Ordinary detection methods can no longer meet the detection needs. With the emergence of alternating electromagnetic field detection technology, this technology has been widely used in seabed detection. However, the high cost of foreign detection is not conducive to the vigorous development of this technology. Therefore, research exc...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N27/83
CPCG01N27/83
Inventor 刘金海杨金崎汪刚张化光马大中卢森骧冯健贾茹杨鑫
Owner NORTHEASTERN UNIV LIAONING
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