International Journal of Applied Electromagnetics and Mechanics - Volume 25, issue 1-4

Authors: Kosmas, Konstantinos | Hristoforou, Evangelos

Article Type: Research Article

Abstract: In this paper, we demonstrate a first approach of a non destructive testing method that is being oriented in detecting mainly near subsurface defects in ferromagnetic materials. This new technique is related to the parametric control and combination of the classic magnetic anomaly detection and the eddy current techniques that can be potentially used in common geometries giving the possibility not only to reveal the presence of defects, but also lead to their reconstruction when being …parallel or perpendicular to the under inspection surface. This method is limited in depths of few mm due to the barrier of the penetration of eddy currents but its contribution in non destructive testing is coplementary to that of ultrasonic testing. Show more

Keywords: Magnetic non-destructive testing, eddy currents, magnetic anomaly detection

DOI: 10.3233/JAE-2007-826

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 25, no. 1-4, pp. 319-324, 2007

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

Article Type: Research Article

Abstract: Eddy Current Techniques (ECT) for Non-Destructive Testing and Evaluation (NDT/NDE) of conducting materials is one of the most application-oriented field of research within electromagnetics. In this work, a novel approach is proposed to classify defects in metallic plates in terms of their depth starting from a set of experimental measurements. The problem is solved by means of a system based on wavelets approach applied to extract relevant information on the specimen under test directly from the …reading and, then, by implementing Fuzzy Inference Systems in order to determine its depth. Finally, Shannon Fuzzy Entropy as well as Subsethood operators have been taken into account to improve the classification methodology. Show more

Keywords: Defect classifying, Non-Destructive Testing, wavelets transform, fuzzy computation

DOI: 10.3233/JAE-2007-786

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 25, no. 1-4, pp. 325-331, 2007

Authors: Rubinacci, Guglielmo | Tamburrino, Antonello | Ventre, Salvatore

Article Type: Research Article

Abstract: This paper is focused on the nondestructive inspection of concrete rebars by using eddy current testing. Many practical low frequency systems are capable of locating and estimating the size of the cross-section of the rebars via calibration charts. Here we develop a quantitative non-iterative imaging method based on a numerical model of the probe-specimen interaction.

Keywords: Non-iterative inductive imaging, NDE, eddy currents, reinforced concrete inspection

DOI: 10.3233/JAE-2007-841

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 25, no. 1-4, pp. 333-339, 2007

Authors: Kikuchi, Hiroaki | Henmi, Yuji | Liu, Tong | Ara, Katsuyuki | Kamada, Yasuhiro | Kobayashi, Satoru | Takahashi, Seiki

Article Type: Research Article

Abstract: Magnetic properties of an iron-based steel derived from its major hysteresis loop are very sensitive to its microstructures and have been, therefore, used for nondestructive evaluation (NDE) of degradation in infrastructure made by ferromagnetic materials. The permeability obtained from small ac field excitation may be a more useful parameter for NDE of ferromagnetic materials than one obtained from a major hysteresis loop from the viewpoints of electricity consumption and real-time measurements. In this paper …a relation between ac permeability, calculated from impedance of coil elements, and dislocation density or grain size of pure iron were clarified. A potential of NDE using ac permeability is also discussed. Show more

Keywords: AC permeability, nondestructive evaluation (NDE), impedance, dislocation density, grain size

DOI: 10.3233/JAE-2007-891

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 25, no. 1-4, pp. 341-346, 2007

Authors: Pávó, József | Maurice, Léa | Prémel, Denis | Lesselier, Dominique

Article Type: Research Article

Abstract: The accuracy of the calculation of the signal due to the interaction of an eddy current testing (ECT) probe and a thin crack in a plate is basically depending on the discretization of the boundary integral equation which is modelling the actual physical arrangement. In this paper a solution method is introduced, where global approximation functions are used for proper discretization of the equivalent dipole density on the thin crack surface in that integral framework. Among …other items, emphasis is put on the evaluation and control of the resulting numerical error. Using such results the automated discretization of rectangularly-shaped thin cracks analysed by an ECT signal prediction software will be shown to become feasible. Show more

Keywords: Eddy current testing, integral equation, error estimation, automated discretization

DOI: 10.3233/JAE-2007-870

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 25, no. 1-4, pp. 347-356, 2007

Authors: Joshi, Ameet | Udpa, Lalita | Udpa, Satish

Article Type: Research Article

Abstract: Magnetic flux leakage (MFL) is one of the most commonly used techniques for the non-destructive evaluation of gas transmission pipelines. A major segment of this network employs seamless pipes. The data obtained from MFL inspection of seamless pipes is contaminated by various sources of noise, including the characteristic seamless pipe noise, lift-off variation of MFL sensor due to motion of the pipe and system noise due to on-board electronics, which can considerably reduce the detectability of …defect signals. This paper presents a new technique to filter the correlated seamless pipe noise (SPN) and identify the defect regions in the MFL data, thereby reducing the data to be analyzed. The proposed filtering algorithm is based on higher order statistics (skewness and kurtosis), of the MFL data and is shown to be more robust than traditional filtering methods. Show more

Keywords: Higher order statistics, skewness, kurtosis, adaptive filtering, denoising, seamless pipe noise

DOI: 10.3233/JAE-2007-892

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 25, no. 1-4, pp. 357-362, 2007

Authors: Vandenbossche, Lode | Duprè, Luc | Melkebeek, Jan

Article Type: Research Article

Abstract: Preisach-based magnetic characterization is applied as a non-destructive method to evaluate material degradation due to metal fatigue. At predetermined interruptions of the cyclic mechanical loading a set of first order symmetric and a set of second order minor magnetisation loops are measured and analysed using both the classical and the moving Preisach model. The evolution of microstructure dependent magnetic features such as the Preisach distribution function, the mean-field parameter k and the local …coercive field distribution Q_{c}(h_{c}) is monitored: k increases and the peak value of Q_{c} decreases with the number of stress cycles. Moreover, for both parameters the rate of change is higher during the last 10% of the fatigue lifetime. Show more

Keywords: Magnetic hysteresis, moving Preisach model, non-destructive evaluation, fatigue

DOI: 10.3233/JAE-2007-787

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 25, no. 1-4, pp. 363-368, 2007

Authors: Chady, Tomasz | Łopato, Przemysław | Sikora, Ryszard | Komorowski, Mieczysław

Article Type: Research Article

Abstract: In this paper a new version of eddy current differential transducer is proposed for evaluation of INCONEL thin plates in order to detect shallow hidden flaws. A 3D-finite element software package was used to analyse various configurations of the excitation coils and select optimal design. A set of experiments was carried out in order to prove usability of the transducer.

Keywords: EC testing, differential transducer

DOI: 10.3233/JAE-2007-788

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 25, no. 1-4, pp. 369-373, 2007

Authors: Deng, Yiming | Zeng, Zhiwei | Tamburrino, Antonello | Udpa, Lalita | Shih, William

Article Type: Research Article

Abstract: Magneto-optic imaging is a recently developed nondestructive evaluation technique that is widely used for detecting cracks and corrosion in aircraft skins. This paper investigates multiple definitions of skewness functions of magneto-optic image data for quantifying and classifying defects originating at rivet sites and thereby substantiating its usefulness in developing automatic defect classification system.

Keywords: Magneto-optic imaging (MOI), skewness, multi-dimensional skewness space (MDSP), moment based skewness method

DOI: 10.3233/JAE-2007-789

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 25, no. 1-4, pp. 375-382, 2007

Authors: Crevecoeur, Guillaume | Hallez, Hans | Van Hese, Peter | D'Asseler, Yves | Dupré, Luc | Van de Walle, Rik

Article Type: Research Article

Abstract: In this paper, the space mapping (SM) technique is used for solving the inverse problem of electroencephalographic dipole source localization. By using SM, we obtained an adequate solution with a minimum of CPU-time by combining the accuracy of a fine model with the speed of a coarse model. The performance when solving the inverse problem using SM versus direct optimisation techniques was investigated in the presence of noise in the measured potentials.

DOI: 10.3233/JAE-2007-825

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 25, no. 1-4, pp. 383-387, 2007