Thickness measurement using liftoff point of intersection in pulsed eddy current responses for elimination of liftoff effect

•LOI phenomenon was demonstrated for both absolute and difference PEC signals.•The behaviors of LOI points were investigated and interpreted in physics.•LOI points were compared with typical PEC features for thickness evaluation.•The experiments match well with the simulations. Pulsed eddy current (...

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Bibliographic Details
Published inSensors and actuators. A. Physical. Vol. 251; pp. 66 - 74
Main Authors Fan, Mengbao, Cao, Binghua, Tian, Guiyun, Ye, Bo, Li, Wei
Format Journal Article
LanguageEnglish
Published Lausanne Elsevier B.V 01.11.2016
Elsevier BV
Subjects
Conductivity
Eddy currents
Electromagnetic sensors
Electromagnetics
Liftoff
Liftoff effect
Liftoff point of intersection
Linearity
Nondestructive testing
Nonferrous
Pulsed eddy current
Reliability analysis
Sensors
Signatures
Thickness measurement
Liftoff point of intersection
Nondestructive testing
Liftoff effect
Electromagnetic sensors
Pulsed eddy current
Thickness measurement
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Summary:•LOI phenomenon was demonstrated for both absolute and difference PEC signals.•The behaviors of LOI points were investigated and interpreted in physics.•LOI points were compared with typical PEC features for thickness evaluation.•The experiments match well with the simulations. Pulsed eddy current (PEC) responses would intersect at a point for a nonferrous plate when only liftoff distance is varied. In this paper, the behaviors of liftoff point of intersection (LOI) points due to a plate with varying conductivity and thickness were investigated and interpreted in physics by means of simulations and experiments. LOI points result from the invariance of the phase spectrum of PEC responses to liftoff effect, and the time of LOI points would increase with an increase of phase spectrum. Subsequently, the signatures of LOI points were compared with the peak heights and time to peaks of PEC signals and their derivatives. The results demonstrate that the signatures of LOI points possess the comparable performances in terms of sensitivity, linearity and measurement range. Moreover, the signatures of LOI points are immune to liftoff variations in nature, which shall enhance the accuracy and reliability of PEC evaluation.
ISSN:0924-4247
1873-3069
DOI:10.1016/j.sna.2016.10.003