Suppressing the lift-off effect in eddy current testing by adjusting the reference voltage

SUN Zhenguo; CAI Dong; LI Dong; ZHANG Wenzeng; CHEN Qiang

doi:10.16511/j.cnki.qhdxxb.2016.22.022

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Journal of Tsinghua University(Science and Technology) ›› 2016, Vol. 56 ›› Issue (6) : 622-625,632. DOI: 10.16511/j.cnki.qhdxxb.2016.22.022

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Suppressing the lift-off effect in eddy current testing by adjusting the reference voltage

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Abstract

Lift-off affects the signal in eddy current testing. A circuit designed to reduce the lift-off effect adjusts the reference voltage based on an analysis of the influence of the lift-off effect on the probe coil voltage. A dephasing and amplification circuit is used to decouple the phase and amplitude to separate the phase and amplitude adjustments to improve the reference voltage adjustment efficiency. A test specimen is designed to validate the feasibility of the method. Tests indicate that the defect signal amplitude with this method is 20 times larger than the signal from the lift-off effect. The influence of lift- off effect on the defect signal can then be ignored with this circuit.

Key words

eddy current testing / lift-off effect / reference voltage / decoupling adjustment

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SUN Zhenguo, CAI Dong, LI Dong, ZHANG Wenzeng, CHEN Qiang. Suppressing the lift-off effect in eddy current testing by adjusting the reference voltage[J]. Journal of Tsinghua University(Science and Technology). 2016, 56(6): 622-625,632 https://doi.org/10.16511/j.cnki.qhdxxb.2016.22.022

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