Theory of thin-skin eddy-current interaction with surface cracks
- Department of Physics, University of Surrey, Guildford, Surrey GU2 5XH (United Kingdom)
Eddy-current non-destructive evaluation is commonly performed at relatively high frequencies at which the skin depths are significantly smaller than the dimensions of a typical crack. A thin-skin analysis of eddy currents is presented in which the electromagnetic fields on the crack faces are described in terms of a potential which obeys a two-dimensional Laplace equation. Solutions of this equation for defects in both magnetic and non-magnetic materials are determined by applying thin-skin boundary conditions at the crack perimeter. The impedance change of an eddy-current coil due to the defect is then calculated by numerical evaluation of one-dimensional integrals over the line of the crack mouth, the impedance integrals having been derived with the aid of a reciprocity relationship. Theoretical predictions are compared with experimental data for long, uniformly deep slots in aluminium and mild steel and good agreement between theory and experiment is obtained. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 543784
- Journal Information:
- Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 9 Vol. 82; ISSN JAPIAU; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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