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Investigation of directional eddy current complex measurements for defect mapping

Lookup NU author(s): Anthony Simm, Professor Gui Yun TianORCiD


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This paper reports an experimental study investigating the interaction of the real and imaginary components of eddy currents with defects and the resulting change in magnetic field under rectangular (directional) coil and circular (non-directional) coil excitation, for the purposes of evaluating surface defects in conductive materials. Eddy currents are induced when an excitation coil is placed near the surface of a conductive material. Discontinuities such as cracks disturb the flow of the eddy currents and thus affect the induced current and magnetic field. These changes can be detected using a magnetic field sensor (Hall sensor). Measurements using an eddy current probe moved over a defect with an X-Y scanner were obtained experimentally. The results illustrate that the imaginary component of the magnetic field responses under directional magnetic field excitation using a rectangular-shaped excitation coil can provide further defect sizing information alongside the real component of the magnetic field, in comparison with a circular-shaped excitation coil.

Publication metadata

Author(s): Simm A, Tian GY

Publication type: Article

Publication status: Published

Journal: Insight

Year: 2010

Volume: 52

Issue: 6

Pages: 320-325

Print publication date: 01/06/2010

ISSN (print): 1354-2575

ISSN (electronic): 1754-4904

Publisher: British Institute of Non-Destructive Testing


DOI: 10.1784/insi.2010.52.6.320


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Funder referenceFunder name
EP/E010458/1Engineering and Physical Sciences Research Council