Defect detection and positioning method of planar array electrical capacitance tomography based on partial fractal dimensions

Abstract

The invention relates to a defect detection and positioning method of planar array electrical capacitance tomography based on partial fractal dimensions. The defect detection and positioning method comprises the following steps: S1, putting a sample to be detected on a planar electrode array sensor in parallel in an alignment manner and measuring a capacitance value at the moment; taking the capacitance value as a capacitance value of a measurement object field; S2, reconstructing an image: reconstructing a dielectric constant distribution image by utilizing an LBP (Local Binary Pattern) algorithm; S3, processing the image: extracting a color matrix corresponding to a defect color in a false-color image; S4, partitioning the reconstructed image into blocks and calculating a fractal dimension of each block; determining a threshold value according to a fractal dimension histogram of the blocks of the reconstructed image; S5, marking a square hole with the fractal dimension which is greater than the threshold value to obtain a final marking result. The invention provides an electrical capacitance tomography detection method based on a planar array electrode, aiming at defects of a sticking layer of a composite material structure for aviation; a fractal theory is applied to defect automatic positioning of the reconstructed image of the electrical capacitance tomography of the planar array electrode, so that the defects of the reconstructed image are automatically marked and the defect positioning precision is improved.

Description

technical field [0001] The invention relates to the field of non-destructive testing of composite materials, in particular to a method for detecting and locating defects in planar array capacitive imaging based on local fractal dimensions. Background technique [0002] In recent years, electrical capacitance tomography (ECT) technology has been widely used in industrial pipeline / multiphase flow monitoring and other fields due to its advantages of non-invasiveness, fast response, and high measurement accuracy, and its electrode arrangement is mainly circular. The planar electrode capacitive imaging sensing technology developed from this not only has the characteristics of traditional ECT technology, but also relies on its own geometric advantages to detect the measured object from a single direction when the geometric space of the measured object field is limited. , has great development prospects in the non-destructive testing of composite materials. [0003] At present, th...

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Problems solved by technology

[0003] At present, the planar array electrode capacitance imaging technology mainly has the following immature problems: (1) low data acquisition accuracy and serious noise interference; (2) the inverse problem of "soft field" effect and ill-posedness; (3) planar array electrode capacitance imaging The selection of high and low calibration of the system in different situations; (4) Detection, quantitative analysis and practical application of small defects of objects

[0004] Due to the serious edge blurring of the image reconstructed by the planar array electrode capacitance imaging system, it affects the measurement accuracy to a large extent. If the defect position is located by artificial marking, the positioning error will be large

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