Defect quantitative evaluation method based on transient characteristics of pulse magnetic flux leakage signal
A technology of transient characteristics and quantitative evaluation, applied in the fields of material magnetic variables, electromagnetic measurement devices, and electric/magnetic depth measurement, etc., it can solve the problem of inability to provide detailed defect information, unfavorable maintenance work, defect depth, defect location and other parameters that are difficult to do. issues such as accurate assessments
Active Publication Date: 2019-09-06
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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[0003]
At present, the magnetic flux leakage detection technology can only judge whether the defect exists, but it is difficult to make an accurate assessment of the defect depth, defect position and other parameters, and cannot provide more detailed information about the defect, which is not conducive to the next maintenance work
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[0045] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.
[0046] The invention discloses a defect quantitative evaluation method based on the transient characteristics of a pulse magnetic flux leakage signal, which includes the following steps:
[0047] (1) Design and manufacture a pulse magnetic flux leakage detection device, including a magnetic core, an excitation coil, and a magnetic sensor, etc., and use the device to detect samples to be tested (such as figure 1 shown).
[0048] (1.1) When using a magnetic flux leakage detection device to detect defects, apply pulsed square wave voltage excitation to the excitation coil, the excitation voltage is U (unit: V), move the probe to detect standard defect samples, and collect data in the y direction (perpendicular to the steel plate surface direction) sensor output signal;
[0049] (1.2) When there is no defect in the detection position, the outp...
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The invention discloses a defect quantitative evaluation method based on transient characteristics of a pulse magnetic flux leakage signal. The defect quantitative evaluation method comprises the following steps that (1) a pulse magnetic flux leakage detecting device, including a magnetic core, an excitation coil, a Hall sensor and the like is designed and manufactured, and the device is utilizedto detect a sample to be tested; (2) a standard defect sample with the same material and thickness as the sample to be tested is manufactured, and a standard defect is detected by using the magnetic flux leakage detecting device; the magnetic flux leakage signal output by the sensor is recorded, and a first-order derivative to time is worked out; (3) the maximum value time t1 and the minimum valuetime t2 of the derivative of the magnetic flux leakage signal are extracted, and a "maximum value time t1-buried depth b" curve a "minimum value time t2-defect depth d" curve are drawn; and (4) the sample to be tested is detected by using the pulse magnetic flux leakage detecting device, and the measured magnetic flux leakage signal is subjected to first-order derivative calculation of time. Themaximum value time T1 and the minimum value time T2 of the derivative are extracted, and the depth and buried depth of the defect can be simultaneously evaluated by comparing the two curves. The defect quantitative evaluation method can quickly, effectively and accurately determine the depth and buried depth of the defect of a tested steel plate, and assistance and guidance are provided for the later repair and maintenance.
Description
technical field [0001] The invention belongs to the technical field of non-destructive testing, and in particular relates to a method for judging the depth and burial depth of steel plate defects based on pulse magnetic flux leakage testing. Background technique [0002] Magnetic flux leakage detection technology is a technology that uses sensors to pick up and analyze the leakage magnetic field at defects. It has the advantages of low cost, fast detection speed, non-contact, high sensitivity, and easy implementation. The pulsed magnetic flux leakage detection technology uses a pulsed square wave signal with a rich spectrum as the excitation, and can obtain defect information at different depths, so it is widely used in the detection of ferromagnetic components such as pipelines, tracks, and cables. [0003] At present, the magnetic flux leakage detection technology can only judge whether the defect exists, but it is difficult to make an accurate assessment of the defect dep...
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Login to View More IPC IPC(8): G01N27/83G01B7/26
CPCG01N27/83G01B7/26Y02E30/30
Inventor 许鹏方舟王平
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS