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2D Geometry Characterization of Cracks From ECT Image Analysis using Planar Coils and GMR-Sensors

Pasadas, D. ; Ribeiro, A. L. ; Ramos, H. ; Rocha, T.

2D Geometry Characterization of Cracks From ECT Image Analysis using Planar Coils and GMR-Sensors, Proc IEEE International Instrumentation and Technology Conf. - I2MTC, Taipei, Taiwan, Vol. 0, pp. 0 - 0, May, 2016.

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Abstract
This paper presents the characterization of cracks in a metallic material using an eddy current testing technique called alternating current field measurement (ACFM). This technique has already shown good results in the field of defect detection because, the current is forced to flow in a uniform direction, making it more predictable and easy to interpret the behavior of the induced current when a crack is present in the metal. However, this technique is limited in the ability to detect cracks when induced currents flow parallel to it. In this paper, a planar probe was built to remove this difficulty. The probe includes two planar coils that induce current in the conductor in different directions and two giant magnetoresistive (GMR) sensors positioned perpendicularly to each other to measure the two perpendicular components of the magnetic field. The Inverse problem technique was applied to get the current density maps from the magnetic field maps. 2D eddy current density images were obtained to visualize the crack geometry.