Estimation of the defects dimension with a GMR eddy current sensor (original) (raw)
This paper presents an experimental system to detect defects in aluminum by eddy currents using a GMR sensor. In three plates of aluminum were constructed defects of 0.6, 1 and 1.4 mm of the width and depths of 0.5, 1, 1.5, 2, 4, 6 and 8 mm, the defects were scanned with the sensing axis perpendicular to the defect length in ten times. The parameters DV and DX were extracted from output voltage signal. Results of this work show that the output voltage of the GMR sensor depends of the width and the depth of the defect. DX depends only on width when the depth of defect is equal or greater than 4 mm. Fitting functions were proposed for the experimental values of DV and DX, these functions show the relationship between the physical dimensions of the defects and parameters DX and DV. Also studied the dependence of DV with the filling factor of the excitation coil.
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