Abstract
An approximate formula for the change in impedance of an eddy current two-coil probe situated above a conducting medium with a volumetric flaw is derived in this paper. The primary field is generated by the superposition of two phase-shifted alternating currents of the same frequency. The Lorentz reciprocity theorem and a layer approximation are used to obtain the change in impedance. Numerical results for different values of the phase difference are presented. These results can be used for developing more selective eddy current testing methods.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
C. V. Dodd, W. E. Deeds, and J. W. Luquire, Integral solutions to some eddy current problems,Int. J. Nondestr. Testing 1(1):29–107 (1969).
A. I. Nikitin, Interaction of cylindrical eddy-current transducers with a multilayered spherical product,Soviet J. Nondestr. Testing 18(4):249–255 (1982).
C. V. Dodd, C. C. Cheng, and W. E. Deeds, Induction coils coaxial with an arbitrary number of cylindrical conductors,J. Appl. Phys. 45(2):638–647 (1974).
J. R. Bowler and S. A. Jenkins, Eddy-current probe impedance due to a volumetric flaw,J. Appl. Phys. 70(3):1107–1114 (1991).
J. R. Bowler, L. D. Sabbagh, and H. A. Sabbagh, A theoretical and computational model of eddy current probes incorporating volume integral and conjugate gradient methods,IEEE Trans. Magnet. 25(3):2650–2664 (1989).
B. Wang, J. P. Basart, and J. C. Moulder, Wavelet expansion in volume integral method of eddy-current modelling, inReview of Progress in Quantitative Nondestructive Evaluation, Vol. 16, D. O. Thompson and D. E. Chimenti, eds. (Plenum, New York, 1996), p. 15.
VIC-3D,An Eddy-Current NDE Code User’s Guide (Sabbagh Associates, Inc., 4635 Morningside Drive, Bloomington, Indiana 47408, September 1993).
M. Ya. Antimirov, A. A. Kolyshkin, and R. Vaillancourt, A perturbation method for asymmetric problems in eddy current testing,Can. Appl. Math. Quart. 1(3):293–310 (Summer 1993).
A. A. Kolyshkin and R. Vaillancourt, Method of solution of forward problems in eddy-current testing,J. Appl. Phys. 77(10):4903–4913 (1995).
R. F. Harrington,Time-harmonic Electromagnetic Fields (McGraw-Hill, New York, 1961).
B. A. Auld, Theoretical characterization and comparison of resonant probe microwave eddy-current methods, inEddy Current Characterization of Materials and Structures, G. Birnbaum and G. Free, eds. (ASTM, Philadelphia, 1981), pp. 332–347.
R. Satveli, J. C. Moulder, B. Wang, and J. H. Rose, Impedance of a coil near an imperfectly layered metal structure: The layer approximation,J. Appl. Phys. 79(6):2811–2821 (1996).
E. N. Derun, A. A. Kolyshkin, and R. Vaillancourt, Interaction of phase-shifted fields of two single-turn coils situated above a conducting medium,J. Nondestr. Eval. 14(4):193–200 (1995).
E. N. Derun, A. A. Kolyshkin, and R. Vaillancourt, Eddy Current Testing Method for Measurements of Electrical Conductivities of Electrically Conducting Materials, Lavian Patent LV 11643 B (International classification G01N27/90), Republic of Latvia, published on December 20, 1997.
Z. Badics, Y. Matsumoto, K. Aoki, F. Nakayasu, M. Uesaka, and K. Miya, Accurate probe-response calculation in eddy current NDE by finite element method,J. Nondestr. Eval. 14(4):181–192 (1995).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Derun, E.N., Kolyshkin, A.A. & Vaillancourt, R. Eddy current probe impedance due to a flaw: The influence of phase-shifted fields. J Nondestruct Eval 17, 47–52 (1998). https://doi.org/10.1007/BF02995482
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF02995482