The authors have developed the layer approximation, a new perturbation method for the change in impedance induced by a three-dimensional defect in a layered metallic structure. The layer approximation becomes exact either in the limit that the relative conductivity change approaches zero or in the limit that the flawed region is nearly layered in the neighborhood of the eddy-current probe. The layer approximation was tested for a benchmark problem that modeled pitting corrosion in a single plate. Agreement between measurement and theory was excellent. An initial study has been reported for pitting corrosion at the faying surface of a model lap-slice. The layer approximation is sufficiently simple that systemativ calculations can be carried out for a variety of defect structures. The dependence of the signal on the probe-defect offset and frequency were reported. Future work should include an optimized coil geometry and a study of the time-domain signal.
Eddy-current detection of pitting corrosion in aircraft lap-splices
Nachweis von Korrosionsnarben in Luftfahrt-Überlappverbindungen mit Wirbelstrom
1996
8 Seiten, 4 Bilder, 8 Quellen
Conference paper
English
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