Identification of crack depths from eddy current testing signal (original) (raw)
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IEEE Transactions on Magnetics, 1998
This paper describes work on the development of a very fast eddy current testing (ECT) signal simulator, and its application to the evaluation of the correlation between cracks and signals. This simulator is developed here based on a reduced magnetic vector potential, edge based finite elements, and the pre-computed unflawed database approach. Using this simulator, three kinds of probes are tested in terms of their linearity and signal to noise ratio. Index Terms-Eddy current testing, steam generator tubes, finite element methods, reduced magnetic vector potentials, precomputed unflawed database approach.
SICE Journal of Control, Measurement, and System Integration, 2009
This paper is concerned with a forward method in inversion systems for identifying crack profiles arising in eddy current testing, using the reduced order Proper Orthogonal Decomposition (POD) techniques. First, an optimal 'ordered' basis of parameter-to-output mapping simulation data is created in the sense that the information captured in the first few basis elements is maximized. Then, in the forward algorithm, a fixed number of the first few basis elements, called the reduced POD basis, are used for computing relevant information with the variation of crack parameters. Since only a small number of basis elements are used, it is able to create an optimized forward algorithm in terms of calculation speed and usage of system resource. Numerical experimental results confirm the effectiveness and reliability of this method.
Discrimination method of through-wall cracks in steam generator tubes using eddy current signals
NDT & E International, 2006
A unique non-destructive technique to discriminate a through-wall crack and to measure the through-wall length of a through-wall crack was developed using the EDM notch specimens and verified by using real fatigue cracks. It is based on the distribution profile of the eddy current signal amplitude along the crack length direction. It was also verified that the internal pressurization of the in situ pressure test induced a plastic deformation of the crack, resulting in a remarkable increase of the signal amplitude.
Transactions of the Institute of Systems, Control and Information Engineers, 2010
This paper is concerned with an optimization method to recover crack profiles from measurement signals obtained by eddy current testing. This inversion technique uses Greedy search algorithm to find the optimum of least-square error between measurement signals and simulation data. In creating simulation data, a database called ECT database is used. This database is constructed as a set of parameters-to-output mapping data, by using hybrid FEM-BEM simulator derived from Maxwell's equations. Numerical experimental results show the effectiveness and feasibility of this method.
Optimized eddy current detection of small cracks in steam generator tubing
Journal of nondestructive evaluation, 1997
A complete, computer based design methodology is described, aiming to develop an eddy current sensor with increased sensitivity to flaws, and reduced sensitivity to probe lift-off. The first part of the paper contains an analysis performed in order to establish detailed criteria for an effective design. Numerical investigations have been carried out and their results are discussed, regarding various problems of detectability and lift-off noise level. Based on these results, in the second part two probe arrangements are proposed, and it is shown how their performance parameters could be further improved.
Detection and Sizing of Cracks in Structural Steel Using the Eddy Current Method
2000
This report summarizes research pertaining to the application of the Eddy Current method as a means of crack detection in structural steel members of highway bridges. Eddy currents are induced when an energized coil is placed near the surface of a conductive material. Discontinuities such as cracks disturb the trajectories of the eddy current and thus affect the magnitude and phase of the induced current. These changes can be detected by the probe. Proper probe design can eliminate the effects arising from spatial changes in material properties. Specimens obtained for laboratory use included a calibration block with electro-discharge machining notches with depths of 0.2, 0.5, and 1.0 mm. Five fatigue crack specimens with crack depths of 0.8, 1.0, 1.5, 2.0, and 3.0 mm were also tested. These specimens were used to evaluate voltage and frequency settings and responses. Fatigue crack profiles were tested. These specimens were used to evaluate voltage and frequency settings and response...
Russian Journal of Nondestructive Testing, 2020
The study of 3D eddy current non destructive testing system for cracks characterization using finite element method requires a great amount of computing time and memory space. In this article, we have validated the developed model and then determined directly the crack length by analyzing the complete signal. Afterwards, we have extracted from the complete sensor sweep signal the maximal amplitude that we have exploited to estimate the crack depth.