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Eddy Current Mapping Inside a Plane Conductor with Flaws

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

Review of Progress in Quantitative Nondestructive Evaluation Vol. 32A, Nº 1, pp. 428 - 435, July, 2012.

ISSN (print): 0094-243X
ISSN (online): 978-0-7354-0888-3

Journal Impact Factor: (in 0)

Digital Object Identifier: 10.1063/1.14789079

Abstract
When a constant field probe with sinusoidal excitation is used to detect flaws inside a conductor, the lines of current must be uniform in a limited area under the influence of the constant excitation field. The existence of flaws inside the metallic material forces the current to deviate from the uniform previous configuration. A magnetic field sensor may be used to measure one component of the magnetic field perturbation due to the eddy current anomalies. In this paper a giant magneto-resistor sensor is used to measure the magnetic field perturbation. The measured field is used to infer about the current perturbation, and a final current density map is obtained. The inversion algorithms are based on a deconvolution process with regularization. The kernel is precisely the field of a single eddy as detected by the magnetic sensor.