International Journal of Applied Electromagnetics and Mechanics - Volume 14, issue 1-4

Authors: Reis, D. Dos | Lambert, M. | Lesselier, D.

Article Type: Research Article

Abstract: Diffusive fields in 3-D configurations, e.g., as those faced when searching for inclusions in conductive planar layered media (a metal slab, a half-space subsoil) at low frequencies, can be modeled via Green's integral formulations that require Green dyads. Such formulations make good use of extended Born approximations in order to express the secondary sources existing within the probed inclusion from the primary fields at same location. Here it is sketched how several such approximations perform in …cases of interest by comparison with full solutions and benchmark measurements. Show more

DOI: 10.3233/JAE-2002-424

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 477-481, 2002

Authors: Pávó, József

Article Type: Research Article

Abstract: A forward calculation method is presented for the analysis of the interaction of a pancake type eddy current testing (ECT) coil and an arbitrary shape thin metal deposit located on the reverse side of a plate specimen. The deposit is modelled as an infinitesimally thin layer where the impedance type boundary conditions are enforced. The given boundary conditions result an integral equation which solution provides the actual distribution of secondary sources modelling the presence of the …deposit. Knowing these secondary sources, the signal of the ECT probe is calculated. Based on the developed forward solution, a proposal for a method reconstructing the shape of the deposit from measured ECT signal is outlined. Show more

DOI: 10.3233/JAE-2002-431

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 483-488, 2002

Authors: Morabito, F.C. | Calcagno, S. | Versaci, M.

Article Type: Research Article

Abstract: Eddy current techniques (ECT) for Nondestructive Testing and Evaluation (NDT/NDE) of conducting materials is one of the most application-oriented field of research within electromagnetics. In this work, a fuzzy approach is proposed to estimate the presence of holes in metallic plates starting from a set of experimental eddy current measurements, carried out at the NDT Lab in Reggio Calabria. The above inverse problem is solved by means of a system that extracts information on the specimen …under test from the measurements and implements a priori constraints to facilitate the detection and characterization of the defect. The method utilizes the concepts of fuzzy inference in order to estimate the location of the defect from a reduced set of features. Show more

DOI: 10.3233/JAE-2002-435

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 489-494, 2002

Authors: Cheng, Weiying | Miya, Kenzo

Article Type: Research Article

Abstract: This paper presents a two-step algorithm to reconstruct parallel cracks from ECT (eddy current testing) signals. The number, the approximate locations and lengths of cracks are determined in the separation stage by employing the eddy current imaging, and the profiles of cracks are obtained in the reconstruction stage.

DOI: 10.3233/JAE-2002-436

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 495-502, 2002

Authors: Taniguchi, T. | Nakamura, K. | Yamada, S. | Iwahara, M.

Article Type: Research Article

Abstract: This paper presents an image processing method for eddy-current testing for the detection of the defects with a specific orientation. The method utilizes the fact that a line-shaped signal is, throught the Fourier transform, mapped onto a line passing through the origin and perpendicular to the orientation of the original signal. Hence, nonseparable fan filters is used to select the frequency components corresponding to the defects orientated in a specific direction. This approach enables more precise …control of the extraction characteristics of signals compared to the iterative application of one-dimensional (1-D) filtering in the vertical and horizontal directions, in which the shape of the pass band is restricted to a geometry made from squares. The effectiveness of the proposed method is shown by a demonstration using a metallic sample with a defect aligned in a number of directions. Show more

DOI: 10.3233/JAE-2002-520

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 503-506, 2002

Authors: Albanese, Raffaele | Rubinacci, Guglielmo | Tamburrino, Antonello | Villone, Fabio

Article Type: Research Article

Abstract: The paper presents the main features of a numerical model for the reconstruction of current sources, on the basis of the knowledge of a set of magnetic measurements. The problem, one of the key issues in biomagnetics research, is solved by extending a method developed in the frame of NDE, for the detection of volume cracks.

DOI: 10.3233/JAE-2002-434

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 507-512, 2002

Authors: Chen, Zhenmao | Preda, Gabriel | Mihalache, Ovidiu | Miya, Kenzo

Article Type: Research Article

Abstract: In this paper, a rapid forward scheme is proposed for simulation of the static magnetic flux leakage (MFL) signals arisen from an object of ferromagnetic material. By storing precalculated distribution data of the unflawed magnetic field into a database, the analysis region for solving the field perturbation due to a crack is greatly reduced by applying the feature that only the magnetic field in the vicinity of a crack can be significantly perturbed due to the …presence of a crack. Having implemented the new scheme into an FEM-BEM hybrid code of the polarization method, the validity of the proposed method is proved by comparing numerical results of the fast forward solver with those obtained by the FEM-BEM polarization code. Show more

DOI: 10.3233/JAE-2002-426

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 513-520, 2002