Abstract
The focus of this chapter is the effect of defects on the impedance of an eddy-current probe coil. Simple flaw shapes are considered, initially, for the purpose of showing how the various characteristics of a defect (its size, shape, location, and filler material, etc.) influence the observed change in impedance of the eddy- current coil. Two regimes are considered: the “small flaw” regime, when the flaw is significantly smaller than the electromagnetic skin depth of the eddy currents in the material, and the “thin-skin’ regime, when a surface crack is significantly deeper than the electromagnetic skin depth. In these regimes, analytic solutions for the impedance change due to the defect can be derived. The analytic solutions give clear insight into the way in which the coil impedance changes due to these and similar flaws.
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Bowler, N. (2019). Flaw Models. In: Eddy-Current Nondestructive Evaluation. Springer Series in Measurement Science and Technology. Springer, New York, NY. https://doi.org/10.1007/978-1-4939-9629-2_9
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DOI: https://doi.org/10.1007/978-1-4939-9629-2_9
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