Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Inversion of Distance and Magnetic Permeability Based on Material-Independent and Lift-off Insensitive Algorithms Using Eddy Current Sensor

Version 1 : Received: 29 October 2020 / Approved: 30 October 2020 / Online: 30 October 2020 (14:36:29 CET)

How to cite: Lu, M.; Meng, X.; Huang, R.; Chen, L.; Peyton, A.; Yin, W. Inversion of Distance and Magnetic Permeability Based on Material-Independent and Lift-off Insensitive Algorithms Using Eddy Current Sensor. Preprints 2020, 2020100643 (doi: 10.20944/preprints202010.0643.v1). Lu, M.; Meng, X.; Huang, R.; Chen, L.; Peyton, A.; Yin, W. Inversion of Distance and Magnetic Permeability Based on Material-Independent and Lift-off Insensitive Algorithms Using Eddy Current Sensor. Preprints 2020, 2020100643 (doi: 10.20944/preprints202010.0643.v1).

Abstract

Eddy current sensors can be used to test the characteristics and measure the parameters of the conductive samples. As the main obstacle of the multi-frequency eddy current sensor, the lift-off distance affects the effectiveness and accuracy of the measurement. In this paper, a material-independent algorithm has been proposed for the restoration of the lift-off distance when using the multi-frequency eddy current sensor, which is based on the approximation under the thin-skin effect. Experiment testing on the performance of the proposed method is presented. Results show that from the dual-frequency inductance, the lift-off distance could be restored with a maximum error of 0.24 mm for the distance up to 12 mm. Besides, the derived lift-off distance is used for the inversion of the magnetic permeability. Based on a lift-off insensitive inductance (LII) feature, the magnetic permeability of steels can be inversed in an iterative manner, with an error of less than 0.6 % for the lift-off distance up to 12 mm.

Keywords

Eddy current; lift-off; material-independent; permeability measurement; non-destructive testing

Subject

ENGINEERING, Automotive Engineering

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