Version 1
: Received: 28 September 2020 / Approved: 29 September 2020 / Online: 29 September 2020 (15:05:41 CEST)
How to cite:
Lu, M.; Chen, L.; Meng, X.; Huang, R.; Peyton, A.; Yin, W. Thickness Measurement of Metallic Film Based on a High-Frequency Feature of Triple-Coil Electromagnetic Eddy Current Sensor. Preprints2020, 2020090717. https://doi.org/10.20944/preprints202009.0717.v1
Lu, M.; Chen, L.; Meng, X.; Huang, R.; Peyton, A.; Yin, W. Thickness Measurement of Metallic Film Based on a High-Frequency Feature of Triple-Coil Electromagnetic Eddy Current Sensor. Preprints 2020, 2020090717. https://doi.org/10.20944/preprints202009.0717.v1
Lu, M.; Chen, L.; Meng, X.; Huang, R.; Peyton, A.; Yin, W. Thickness Measurement of Metallic Film Based on a High-Frequency Feature of Triple-Coil Electromagnetic Eddy Current Sensor. Preprints2020, 2020090717. https://doi.org/10.20944/preprints202009.0717.v1
APA Style
Lu, M., Chen, L., Meng, X., Huang, R., Peyton, A., & Yin, W. (2020). Thickness Measurement of Metallic Film Based on a High-Frequency Feature of Triple-Coil Electromagnetic Eddy Current Sensor. Preprints. https://doi.org/10.20944/preprints202009.0717.v1
Chicago/Turabian Style
Lu, M., Anthony Peyton and Wuliang Yin. 2020 "Thickness Measurement of Metallic Film Based on a High-Frequency Feature of Triple-Coil Electromagnetic Eddy Current Sensor" Preprints. https://doi.org/10.20944/preprints202009.0717.v1
Abstract
Previously, various techniques have been proposed for reducing the lift-off effect on the thickness measurement of the non-magnetic films, including the peak-frequency feature and phase feature in the Dodd-Deed analytical formulation. To realise a real-time feedback response on the thickness monitoring, the phase term in the Dodd-Deeds formulation must be taken off the integration. Previous methods were based on the slow change rate of the phase term when compared to the rest of the term – the magnitude term. However, the change rate of the phase term is still considerable for a range of working frequencies. In this paper, a high-frequency feature has been found. That is, the ratio between the imaginary and real part of the phase term is proportional to the integral variable under high frequencies. Based on this proportion relationship, the phase term has been taken out; and a thickness algorithm has been proposed. By combing the measured impedance from the custom-built sensor (three coils), the thickness of the metallic film can be reconstructed. Experiments have been carried out for the verification of the proposed scenario. Results show that the thickness of the metal film can be reconstructed with a small error of less than 2 %, and immune to a reasonable range of lift-offs.
Keywords
Eddy current testing; thickness measurement; non-destructive testing; lift-off; real-time monitoring
Subject
Engineering, Automotive Engineering
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.