Method for discriminating depth of nonconductor defect based on multi-pair electrode capacitance imaging detection technology

Abstract

The invention discloses a method for discriminating the depth of a nonconductor defect based on a multi-pair electrode capacitance imaging detection technology, and relates to the field of nondestructive detection signal processing. The method comprises the following step: receiving input multi-pair electrode capacitance imaging detection signals, wherein the detection signals include a defect detection signal Yn and a zero-defect detection signal YSn; obtaining the defect signal change value delta Yn= Yn - YSn, and judging whether the defect signal change value delta Yn is greater than or equal to a preset threshold Pn or not; judging that the defect does not exist if not; judging that the defect exists if so; carrying out coordinate transformation on the abscissa Xn corresponding to thedefect signal Yn to obtain a transformed abscissa HXn = Xn-dn / 2; transforming the defect signal Yn to obtain a transformed ordinate HYn =Yn. / YSn; drawing a curve map according to the abscissa HXn andthe ordinate HYn; determining the maximum electrode pair number Ca when the number of a trough, corresponding to the defect, in the curve map is 1; determining the minimum electrode pair number Cb when the number of troughs, corresponding to the same defect, in the curve map is 2; and determining that the depth of the defect is between the effective detection depths of the electrode pair Ca and Cb.

Description

technical field [0001] The invention relates to the field of non-destructive detection signal processing, in particular to a method for discriminating the depth of non-conductor defects based on a multi-pair electrode capacitive imaging detection technology. Background technique [0002] The multi-pair electrode capacitive imaging detection technology is a new type of detection technology developed based on the single-pair electrode capacitive imaging detection technology. The technology of detecting defects by electric field, when the defect is located in the effective detection electric field between the coplanar electrode plates, the defect will disturb the distribution of the effective electric field and affect the number of charges measured on the detection plate, so as to achieve the purpose of detecting defects. [0003] Although single-pair electrode capacitive imaging detection technology can detect conductor surface defects and non-conductor internal defects, the d...

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Problems solved by technology

[0003] Although single-pair electrode capacitive imaging detection technology can detect conductor surface defects and non-conductor internal defects, the detection results can only roughly reflect the length and width information of defects, and cannot reflect the depth information of non-conductor internal defects

With the rapid development of non-destructive testing technology toward refinement and visualization, single-pair electrode capacitance imaging detection, which lacks the important parameter of defect depth information, faces many disadvantages; To a certain extent, it can reflect the depth information of non-conductor internal defects. During the detection process, the conductor material needs to be placed under the non-conductor material, and the reflected defect depth information is only the upper or lower part of the non-conductor material; and for the same It takes a lot of time to scan the defect multiple times, and the efficiency is low; at the same time, when the single-pair electrode capacitive imaging detection technology detects defects under multiple lift-off heights, it is necessary to accurately grasp the variation range of the lift-off height. If the lift-off height If the grasp is not accurate, it will cause misjudgment of the depth information of the internal defects of non-conductor materials, resulting in inaccurate test results

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