Inversion of eddy-current data and the reconstruction of three-dimensional flaws

Author

Sabbagh, H.A. ; Radecki, D.L. ; Barkeshli, S. ; Shamee, B. ; Treece, J.C. ; Jenkins, S.A.

Author_Institution

Sabbagh Associates Inc., Bloomington, IN, USA

Volume

26

Issue

2

fYear

1990

fDate

3/1/1990 12:00:00 AM

Firstpage

626

Lastpage

629

Abstract

Inverse scattering models of the type that is often used to invert eddy-current data are inherently nonlinear, because they involve the product of two unknowns, the flaw conductivity and the true electric field within the flaw. Computational inverse models, therefore, often linearize the problem by assuming that the electric field within the flaw is known a priori. In the present work, the authors describe such a linearized model; it is fully three-dimensional and applies to metals, such as stainless-steel, or to advanced composites, such as graphite-epoxy. The model is based on an integral equation that is then discretized by means of the method of moments. The measured data are inverted by means of the conjugate gradient algorithm. an example is shown in which a linear classifier algorithm is used to improve convergence of the conjugate gradient algorithm

Keywords

eddy current testing; flaw detection; integral equations; inverse problems; numerical analysis; advanced composites; conjugate gradient algorithm; convergence; discretized; eddy current data inversion; eddy current testing; integral equation; inverse scattering models; linear classifier algorithm; linearized model; metals; method of moments; stainless-steel; three dimensional flaws reconstruction; Conductivity; Couplings; Current density; Green´s function methods; Integral equations; Inverse problems; Moment methods; Nonlinear equations; Region 1; Slabs;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.106395

Filename

106395