Review of Advances in Quantitative Eddy Current Nondestructive Evaluation

A comprehensive review of advancements in eddy current (EC) modeling is presented. This paper contains three main sections: a general treatise of EC theory, the thin skin EC forward modeling, and the EC inverse problem. (1) The general treatise of eddy current theory begins with an exposition of the reciprocity formulas for evaluating probe impedance changes, which are derivable from first principles. Two versions of the reciprocity formulas, one with a surface integral and the other with a volume integral, are given. Any particular type of defect, as well as both one-port and two-port probes, can be treated. Second, a brief account of analytical and numerical methods for calculating the field distributions is presented. Third, theory of probe/material interactions with various defect types is described. (2) The paper then proceeds to the forward modeling section, which contains a detailed treatment of the eddy current forward problem for surface breaking cracks and EDM notches in the thin skin approximation. (3) The inverse problem section begins with a general review of commonly used inversion methods, exemplified by selected references from the literature, followed by more detailed examinations of EC inversions for surface breaking cracks and slots. The last part of this section is devoted to the inverse problem for layered structures. Although being a review in nature, the paper contains a number of new accounts for time-domain eddy current interactions. In particular, a modification is proposed to the reciprocity formula in order to take a better account of pulsed eddy current signals.

[1]  S. K. Burke,et al.  Benchmark problems for defect size and shape determination in eddy-current nondestructive evaluation , 1996 .

[2]  D. Pozar.  Microwave Engineering , 1990 .

[3]  W. E. Deeds,et al.  Induction coils coaxial with an arbitrary number of cylindrical conductors , 1974 .

[4]  William Lord.  Electromagnetic Methods of Nondestructive Testing , 1985 .

[5]  Erol Uzal,et al.  Impedance of coils over layered metals with continuously variable conductivity and permeability: Theory and experiment , 1993 .

[6]  G Birnbaum,et al.  Eddy-Current Characterization of Materials and Structures , 1981 .

[7]  H. Libby.  Introduction to Electromagnetic Nondestructive Test Methods , 1971 .

[8]  D. H. Michael,et al.  The inversion of surface potential measurements to determine crack size and shape , 1988 .

[9]  Zsolt Badics,et al.  Accurate probe-response calculation in eddy current NDE by finite element method , 1995 .

[10]  Erol Uzal,et al.  Thickness and conductivity of metallic layers from eddy current measurements , 1992 .

[11]  J. Bowler.  Eddy current calculations using half‐space Green’s functions , 1987 .

[12]  Wesley E. Snyder,et al.  Eddy current image restoration by constrained gradient descent , 1991 .

[13]  Shridhar C. Nath.  Finite element and boundary element analysis of electromagnetic NDE phenomena , 1992 .

[14]  R. Beissner.  Boundary element model of eddy current flaw detection in three dimensions , 1986 .

[15]  Helmut Ermert,et al.  Broadband holography applied to eddy current imaging by using signals with multiplied phases , 1993 .

[16]  C. Dodd,et al.  ANALYTICAL SOLUTIONS TO EDDY--CURRENT PROBE COIL PROBLEMS. , 1968 .

[17]  R. E. Beissner.  Slots vs. cracks in eddy current NDE , 1994 .

[18]  B. A. Auld,et al.  Spatial frequency analysis and matched filtering in electromagnetic nondestructive evaluation , 1983 .

[19]  Stephen J. Norton,et al.  Eddy-current interaction with an ideal crack. II. The inverse problem , 1994 .

[20]  R. Harrington.  Time-Harmonic Electromagnetic Fields , 1961 .

[21]  Albert Feldman,et al.  Eddy‐current losses due to a surface crack in conducting material , 1977 .

[22]  J. Bowler.  Eddy‐current interaction with an ideal crack. I. The forward problem , 1994 .

[23]  P. Morse,et al.  Methods of theoretical physics , 1955 .

[24]  Analysis of eddy‐current interaction with a surface‐breaking crack , 1994 .

[25]  R. E. Beissner,et al.  Theory of eddy currents induced by a nonsymmetric coil above a conducting half‐space , 1984 .

[26]  D. Paris,et al.  Basic Electromagnetic Theory , 1969 .

[27]  S. A. Jenkins,et al.  Eddy‐current probe impedance due to a volumetric flaw , 1991 .

[28]  Satish M. Nair,et al.  Low‐frequency asymptotics for eddy currents in a conducting half‐space in the absence and presence of inhomogeneities , 1991 .

[29]  B. P. Hildebrand,et al.  The eddy current probe as a holographic transducer , 1993 .

[30]  C. Kittel.  Introduction to solid state physics , 1954 .

[31]  John R. Bowler,et al.  Theory of eddy current inversion , 1993 .

[32]  D. H. Michael,et al.  Thin‐skin electromagnetic fields around surface‐breaking cracks in metals , 1988 .

[33]  R. Collin.  Foundations for microwave engineering , 1966 .

[34]  James H. Rose,et al.  Rapid inversion of eddy current data for conductivity and thickness of metal coatings , 1995 .

[35]  S. K. Burke,et al.  Eddy‐current inversion in the thin‐skin limit: Determination of depth and opening for a long crack , 1994 .

[36]  S K Burke.  Impedance of a horizontal coil above a conducting half-space , 1986 .