Affiliations: [a] School of Information Science and Technology, ShanghaiTech University, Shanghai, China | [b] Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, USA
Correspondence:
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Corresponding authors: Chaofeng Ye, School of Information Science and Technology, ShanghaiTech University, Shanghai, 201210, China. Email: yechf@shanghaitech.edu.cn. Anders Rosell, Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, USA. Email: rosellsv@msu.edu
Abstract: This paper presents an eddy current (EC) probe with orthogonal excitation coils that can change the exciting current direction electrically and tunnel magnetoresistive (TMR) sensor for inspection of stacked CFRP. As CFRP is electrically anisotropic, eddy current excited along the fiber direction is stronger than in other directions. A high sensitivity TMR sensor located at the center of the two orthogonal coils measures the z component of induced magnetic field (Bz) which constitutes the probe signal. The output of the sensor is 0 if the induced currents are symmetric about the sensor. Signals of defects in different orientations depend on the direction of the exciting current. The operation of the probe is validated using a finite element model. A prototype was built and experimental results from CFRP sample with defects in different orientations are presented and analyzed.
