International Journal of Applied Electromagnetics and Mechanics - Volume 15, issue 1-4

Authors: Igarashi, Hajime | Kost, Arnulf | Honma, Toshihisa

Article Type: Research Article

Abstract: This paper discusses reconstruction of magnetic charge distribution on a planar region for non-destructive evaluation. Reconstruction is performed by using the magnetic fields measured on a plane above the charge region as input data. The present method needs only one matrix inversion whose computational time is expected to be shorter than the method based on optimization processes. It is shown that the reconstruction is successful when the unknown vector is appropriately regularized in order that the …corresponding singular vectors become smooth. The L-curve method works well for determination of the value of the regularization parameter. Show more

DOI: 10.3233/JAE-2002-509

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 15, no. 1-4, pp. 257-260, 2002

Authors: Kubo, Shiro | Kuchinishi, Manabu | Sakagami, Takahide | Ioka, Seiji

Article Type: Research Article

Abstract: The electric potential CT (computed tomography) method proposed by the present authors was applied to the identification of delamination defect in layered carbon fiber reinforced plastics (CFRP) composites, which have strong anisotropy in electric conductivity. The electric potential readings on the top surface of the layered composite materials was used for the identification. The anisotropy of the electric conductivity of each layer was taken into account in the boundary element calculations of electric potential distribution. Numerical …simulations were made on the identification of elliptical delaminations on the interface of layers. It was found that the method was applicable for the estimation of the location and size of delamination even in the presence of considerable measurement noise. Show more

DOI: 10.3233/JAE-2002-459

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 15, no. 1-4, pp. 261-267, 2002

Authors: Dobmann, Gerd | Altpeter, Iris | Becker, Rainer | Lang, Marco | Kern, Rolf | Yashan, Andrij | Theiner, Werner

Article Type: Research Article

Abstract: Nondestructive characterization (NDC) of materials is a technology of increasing application by industrial users for process monitoring and control as well as in predictive maintenance procedures integrated in plant lifetime management systems. The main reason for this fact in materials processing is the need for a better process understanding and mastering in order to produce quality according to a zero-defect-principle and the objective to reduce non-conformities compared with a given quality specification. This …means: Integration of NDC by use of intelligent sensors into monitoring and control systems to predict mechanic properties and to detect and document their discontinuities. For lifetime management of components in plants NDC is asked for to support lifetime prediction procedures, which have to be observed if lifetime extension is an objective to reduce costs. Show more

DOI: 10.3233/JAE-2002-510

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 15, no. 1-4, pp. 269-274, 2002

Authors: Shindo, Yasuhide | Horiguchi, Katsumi

Article Type: Research Article

Abstract: The bending of through-cracked ferromagnetic plates in a static magnetic field is investigated to show the effect of induced magnetization. A simple experimental technique employing strain gages is used to determine the magnetic moment intensity factor. The theoretical results agree very well with the experimental data. The scattering of time harmonic flexural waves by a through crack in an infinite plate under a uniform magnetic field is also studied.

DOI: 10.3233/JAE-2002-465

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 15, no. 1-4, pp. 275-281, 2002

Authors: Cranganu-Cretu, Bogdan | Preda, Gabriel | Mihalache, Ovidiu | Chen, Zhenmao | Miya, Kenzo

Article Type: Research Article

Abstract: B-H curve reconstruction starting from magnetic flux leakage (MFL) signals measured outside the tested specimen is attempted. Non-linear constitutive relation is modeled by means of three parameters, suitable for describing low fields magnetization curve. A FEM-BEM approach is used to solve the forward problem whilst the inverse problem is tackled with a genetic algorithm application. Results of the reconstruction are presented.

DOI: 10.3233/JAE-2002-466

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 15, no. 1-4, pp. 283-289, 2002

Authors: Simone, G. | Morabito, F.C. | Polikar, R. | Ramuhalli, P. | Udpa, L. | Udpa, S.

Article Type: Research Article

Abstract: In this paper, we present two feature extraction techniques for the classification of ultrasonic NDE signals acquired from weld inspection regions of boiling water reactor piping of nuclear power plants. The classification system consists of a pre-processing block that extracts features from the incoming patterns, and of an artificial neural network that assigns the computed features to a particular class of defect present on the inspected pipe. The two techniques are respectively based on the discrete …Gabor transform (DGT) and on the discrete wavelet transform (DWT); a third feature extraction technique, based on the clustering of the wavelet coefficients, is also presented. The results carried out by artificial neural networks trained and tested using the described feature extraction techniques, demonstrate the usefulness of the clustered DWT method with respect to the well known techniques of DGT and DWT. Show more

DOI: 10.3233/JAE-2002-462

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 15, no. 1-4, pp. 291-294, 2002

Authors: Nagae, Yuji | Aoto, Kazumi

Article Type: Research Article

Abstract: A study on non-destructive technique for creep damage of type304 stainless steel was performed. In this study, we concentrated on the magnetic field change with creep damage. This technique has a possibility that the damage before crack initiation is detected. We report that the results on the magnetic field change during creep damage progress, in order to examine the applicability of this technique based on magnetic field change to time-dependent damage. Though type304 stainless steel is …a paramagnetic material, the leakage flux density of creep damaged specimen changes obviously, as compared with that of aged specimen. Show more

DOI: 10.3233/JAE-2002-463

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 15, no. 1-4, pp. 295-300, 2002

Authors: Weber, W. | Feiste, K.L. | Reimche, W. | Stegemann, D.

Article Type: Research Article

Abstract: A wide range of pressurized systems in the field of chemical and power-plant techniques are made of austenitic material because of its special corrosion and temperature stability. Concerning safety components like pressure vessels and pipe systems, the quality of these components has to be controlled during production, and their condition during use has to be inspected in defined intervals. Especially for nuclear power plants, the detection of defects as well as the early recognition of material …phase transformations in austenitic material is an important contribution to the assurance of the system integrity. Inside this paper, the results of the qualitative and quantitative non-destructive evaluation of this phenomenon will be presented. Therefore, material physics, FEM-calculations and applied advanced electromagnetic testing techniques will be explained. Show more

DOI: 10.3233/JAE-2002-464

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 15, no. 1-4, pp. 301-308, 2002

Authors: Nakasone, Yuji | Iwasaki, Yoshifumi | Shimizu, Tetsu

Article Type: Research Article

Abstract: The present study investigates a method for the non-destructive detection of damage in an austenitic stainless steel SUS 304 by the use of martensitic transformation. Volume fraction of α' martensite transformed in uniformly stretched SUS304 plates was measured and expressed as a function of the applied strain level ε. The distributions of α' phase in the plastic wake regions produced around fatigue cracks were then electromagnetically measured in fatigued SUS 304 plate …specimens. The results were compared with the distributions of magnetic flux density B_{z} above the fatigue cracks in the specimens magnetized by a strong magnetic field higher than 0.4 T. It was revealed that the B_{z} distributions reflected the α" phase distributions in the wake regions: i.e., the distance between the points where B_{z} reached the minimum and the maximum had a high correlation with the fatigue crack length, and the minimum and the maximum values of B_{z} showed a linear relationship with the applied stress intensity factor range ΔK. These results imply that not only the crack length but also the fatigue damage can be detected effectively in an electromagnetic non-destructive way. Show more

DOI: 10.3233/JAE-2002-468

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 15, no. 1-4, pp. 309-313, 2002

Authors: Sukegawa, T. | Uesaka, M.

Article Type: Research Article

Abstract: We performed magnetic nondestructive evaluation of degradation of nuclear pressure vessel steels due to mechanical loading as a fundamental research. We measured magnetic properties of low alloy steel samples, which were degraded due to tensile and cyclic loads. Magnetic hysteresis curves change depending on the loading conditions. The changes of the coercive force, residual magnetic flux density and permeability were obtained and analyzed in details as a function of the residual strain. Based on the above …results, we performed the sensitivity analysis of magnetic property changes for the mechanical load. Finally we concluded that the incremental permeability at H = 0 is the most sensitive index for early degradation due to the mechanical loads. The feasibility of application of this magnetic technique to the evaluation of degradation due to neutron mechanical and thermal loading is now under consideration. Show more

DOI: 10.3233/JAE-2002-467

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 15, no. 1-4, pp. 315-321, 2002