Koch curve fractal geometry excitation probe for eddy current non-destructive testing

Chen, Guolong; Zhang, Weimin; Pang, Weihan

doi:10.1016/j.measurement.2018.04.031

Cited by 23 publications

(12 citation statements)

References 28 publications

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“…The sensitivity of the eddy current sensor is affected by the eddy current distribution. Thus, Chen et al [ 21 ] proposed using the fractal Koch curve as exciting coils of the eddy current sensor. To quantitatively study the eddy current distribution, Zhang et al [ 22 ] and Chen et al [ 23 ] proposed using the angular spectrum and information entropy.…”

Section: Introductionmentioning

confidence: 99%

Two Novel Information Entropy Indices for Analysis of the Eddy Current Distribution

Chen

2018

Entropy

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The Koch curve exciting coil eddy current sensor is a kind of novel flexible planar eddy current probe. In this study, an intersection angle spectrum entropy index and a radial direction energy spectrum entropy were proposed to evaluate the eddy current distribution. Eddy current distributions induced by one turn of a circular coil and one turn of a second order Koch curve coil feed with different exciting frequency alternative currents and at different lift-off distances, were simulated and the eddy current distributions varying with lift-off distance in different exciting frequencies were compared by the two proposed indices. With the increase of the lift-off distance or the decrease of exciting frequency, the similarity between the shape of the Koch curve and the eddy current distribution became weakened and the degree of the concentration of the eddy current distribution in the specimen under the exciting coil was loosened.

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Section: Introductionmentioning

confidence: 99%

Two Novel Information Entropy Indices for Analysis of the Eddy Current Distribution

Chen

2018

Entropy

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“…In Figures 13 and 10, the performance of the Koch A probe is better than that of the circular probe, because the Koch curve can induce the eddy current in the specimen distributed in more directions in a smaller space domain, and the eddy current can be better disturbed by the short defect which is perpendicular to the scanning direction. Then, why the performance of the Koch A probe excels that of Koch B probe may be because of the eddy current distributions induced by the two probes [22]. In the scanning direction, the eddy current distribution of the Koch A probe is convex to external, but the eddy current distribution of the Koch B probe is invaginated internally.…”

Section: Experiments For Different Depth Defect Detectionmentioning

confidence: 99%

“…Chen et al adopted the fractal geometry Koch curves to design the exciting coil of the EC probes for the first time [22]. In that study, the Koch curves were used as the exciting coil and the circular spiral as the pick-up coil.…”

Section: Introductionmentioning

confidence: 99%

A Novel Planar Differential Koch Fractal Eddy Current Probe with Parallel Wound Topological Structure

2021

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Flexible planar eddy current probes are widely used to detect conductive components with complex surface. In this study, topological transformation is applied to design a differential Koch coil exciting eddy current probe. Two kinds of Koch exciting coils, Koch A and Koch B , were obtained by topological transformation from a three-dimensional differential exciting eddy current probe. Finite element model simulation is conducted to visualize the differences of eddy current distributions induced by the probes and get the defect signal. A detailed comparison is made among the two kinds of Koch eddy current probes and a circular eddy current probe by experiments. The experiments demonstrate that the sensitivity of the Koch A eddy current probe is higher than that of another two probes for detecting the defect which is shorter than the size of the probe. This work provides a novel method for improving the performance of eddy current probes in the coil structure design.

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“…For the spaced domain type of the flexible EC probe, the idea of the EC distribution adjustment is proposed by using the fractal geometry Koch curve exciting coil. 18 This idea is based that the shape of eddy current distribution in the specimen is similar to the shape of the exciting coils, so Koch coil may induce a Koch-like EC distribution, which may adjust the ECs distributing in more directions in the small space region to boost the performance of short defects detectable of the planar EC probe.…”

Section: Introductionmentioning

confidence: 99%

Quantitative evaluation of eddy current distribution by relative entropy and cross entropy

Chen

Zheng

2021

Measurement and Control

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Koch curve exciting coil of an eddy current probe can adjust the eddy current distributing in more directions at a small domain to enhance the sensitivity of eddy current probe for short defect detection. In this study, a relative entropy and a cross entropy of tangential intersection angle spectrum are proposed to evaluate the eddy current distributions in the different directions when the eddy current probe is positioned at different lift-off distances and excited by different exciting frequency alternative currents. The eddy current distributions induced by a circular and a fractal Koch curve exciting coils are analyzed by the two entropy indices. With the increasing of the lift-off distance or the decreasing of the exciting frequency, the eddy current distributions induced by the Koch curve exciting coil are close to those induced by the circular exciting coil.

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Koch curve fractal geometry excitation probe for eddy current non-destructive testing

Cited by 23 publications

References 28 publications

Two Novel Information Entropy Indices for Analysis of the Eddy Current Distribution

Two Novel Information Entropy Indices for Analysis of the Eddy Current Distribution

A Novel Planar Differential Koch Fractal Eddy Current Probe with Parallel Wound Topological Structure

Quantitative evaluation of eddy current distribution by relative entropy and cross entropy

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