A PEC Thrice Subtraction Method for Obtaining Permeability Invariance Feature in Conductivity Measurement of Ferromagnetic Samples

Conductivity, as an important index of structural health monitoring, can be used to evaluate heat treatment condition, and sort different materials or measure the stress of mechanical parts. However, the permeability of a measured sample has significant impact on the detected signal in pulsed eddy c...

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Bibliographic Details
Published inApplied sciences Vol. 9; no. 13; p. 2745
Main Authors Wen, Dongdong, Fan, Mengbao, Cao, Binghua, Xue, Zhian, Wang, Ping
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.07.2019
Subjects
conductivity
Electrical conductivity
Electrical resistivity
Environmental changes
Environmental effects
Ferromagnetic materials
ferromagnetic sample
Invariance
Inverse problems
Magnetic fields
Magnetic permeability
Permeability
pulsed eddy current
Sensors
Subtraction
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Summary:Conductivity, as an important index of structural health monitoring, can be used to evaluate heat treatment condition, and sort different materials or measure the stress of mechanical parts. However, the permeability of a measured sample has significant impact on the detected signal in pulsed eddy current (PEC) testing, which is prone to measurement errors due to the effect of permeability change. In this paper, a thrice subtraction method is investigated and utilized to obtain a permeability invariance (PI) feature for reducing permeability effect in conductivity measurement of ferromagnetic samples. The thrice subtraction method is based on the PEC signals of sample and air, the difference signal between the difference PEC signal and its normalization signal, and the difference signal between the difference normalization signal and its standard deviation. In the thrice subtraction signals, the behavior of the obtained PI feature is analyzed by experiments and simulations. The results demonstrate that the thrice subtraction method is a practicable program and the PI feature is potential to measure the conductivity of ferromagnetic samples. The work reported in this paper provides an effective approach to obtain a PI feature for estimating the conductivity of ferromagnetic samples without a permeability effect.
ISSN:2076-3417
2076-3417
DOI:10.3390/app9132745