TITLE

Inversion of open cracks using eddy-current probe impedance measurements

AUTHOR(S)
Bowler, J. R.
PUB. DATE
May 2000
SOURCE
AIP Conference Proceedings;2000, Vol. 509 Issue 1, p529
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Crack profiles have been estimated by the inversion of eddy-current probe impedance data. In the calculations, the direct problem is solved numerically to obtain predictions of impedance. A penalty function is constructed quantifying the overall difference between predictions and measurements. The crack shape is found by minimizing the penalty function using a conjugate gradient algorithm. Clearly, the inversion is limited to the range of frequencies in which the solution of the direct problem is valid. In previous studies, the direct problem has been solved for two limiting cases involving low and high frequency approximations respectively. In the low frequency case, the skin depth is assumed large compared with the crack opening and in the high frequency calculations. It is assumed to be very much smaller than the crack depth and length. Here, intermediate frequencies are considered in which the crack opening is not negligible and the skin depth is of the same order of magnitude as the other crack dimensions. The intermediate frequency calculations of crack shapes from eddy-current probe impedance measurements show good agreement with the observed profiles. © 2000 American Institute of Physics.
ACCESSION #
6029086

 

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