Inverse source problems for eddy current equations
International Nuclear Information System (INIS)
Rodríguez, Ana Alonso; Valli, Alberto; Camaño, Jessika
2012-01-01
We study the inverse source problem for the eddy current approximation of Maxwell equations. As for the full system of Maxwell equations, we show that a volume current source cannot be uniquely identified by knowledge of the tangential components of the electromagnetic fields on the boundary, and we characterize the space of non-radiating sources. On the other hand, we prove that the inverse source problem has a unique solution if the source is supported on the boundary of a subdomain or if it is the sum of a finite number of dipoles. We address the applicability of this result for the localization of brain activity from electroencephalography and magnetoencephalography measurements. (paper)
Sabbagh, Harold A; Sabbagh, Elias H; Aldrin, John C; Knopp, Jeremy S
2013-01-01
Computational Electromagnetics and Model-Based Inversion: A Modern Paradigm for Eddy Current Nondestructive Evaluation describes the natural marriage of the computer to eddy-current NDE. Three distinct topics are emphasized in the book: (a) fundamental mathematical principles of volume-integral equations as a subset of computational electromagnetics, (b) mathematical algorithms applied to signal-processing and inverse scattering problems, and (c) applications of these two topics to problems in which real and model data are used. By showing how mathematics and the computer can solve problems more effectively than current analog practices, this book defines the modern technology of eddy-current NDE. This book will be useful to advanced students and practitioners in the fields of computational electromagnetics, electromagnetic inverse-scattering theory, nondestructive evaluation, materials evaluation and biomedical imaging. Users of eddy-current NDE technology in industries as varied as nuclear power, aerospace,...
Inverse problems in eddy current testing using neural network
Yusa, N.; Cheng, W.; Miya, K.
2000-05-01
Reconstruction of crack in conductive material is one of the most important issues in the field of eddy current testing. Although many attempts to reconstruct cracks have been made, most of them deal with only artificial cracks machined with electro-discharge. However, in the case of natural cracks like stress corrosion cracking or inter-granular attack, there must be contact region and therefore their conductivity is not necessarily zero. In this study, an attempt to reconstruct natural cracks using neural network is presented. The neural network was trained through numerical simulated data obtained by the fast forward solver that calculated unflawed potential data a priori to save computational time. The solver is based on A-φ method discretized by using FEM-BEM A natural crack was modeled as an area whose conductivity was less than that of a specimen. The distribution of conductivity in that area was reconstructed as well. It took much time to train the network, but the speed of reconstruction was extremely fast after once it was trained. Well-trained network gave good reconstruction result.
EDDYMULT: a computing system for solving eddy current problems in a multi-torus system
International Nuclear Information System (INIS)
Nakamura, Yukiharu; Ozeki, Takahisa
1989-03-01
A new computing system EDDYMULT based on the finite element circuit method has been developed to solve actual eddy current problems in a multi-torus system, which consists of many torus-conductors and various kinds of axisymmetric poloidal field coils. The EDDYMULT computing system can deal three-dimensionally with the modal decomposition of eddy current in a multi-torus system, the transient phenomena of eddy current distributions and the resultant magnetic field. Therefore, users can apply the computing system to the solution of the eddy current problems in a tokamak fusion device, such as the design of poloidal field coil power supplies, the mechanical stress design of the intensive electromagnetic loading on device components and the control analysis of plasma position. The present report gives a detailed description of the EDDYMULT system as an user's manual: 1) theory, 2) structure of the code system, 3) input description, 4) problem restrictions, 5) description of the subroutines, etc. (author)
International Nuclear Information System (INIS)
Yusa, Noritaka; Machida, Eiji; Janousek, Ladislav; Rebican, Mihai; Chen, Zhenmao; Miya, Kenzo
2005-01-01
This paper evaluates the applicability of eddy current inversion techniques to the sizing of defects in Inconel welds with rough surfaces. For this purpose, a plate Inconel weld specimen, which models the welding of a stub tube in a boiling water nuclear reactor is fabricated, and artificial notches machined into the specimen. Eddy current inspections using six different eddy current probes are conducted and efficiencies were evaluated for the six probes for weld inspection. It is revealed that if suitable probes are applied, an Inconel weld does not cause large noise levels during eddy current inspections even though the surface of the weld is rough. Finally, reconstruction of the notches is performed using eddy current signals measured using the uniform eddy current probe that showed the best results among the six probes in this study. A simplified configuration is proposed in order to consider the complicated configuration of the welded specimen in numerical simulations. While reconstructed profiles of the notches are slightly larger than the true profiles, quite good agreements are obtained in spite of the simple approximation of the configuration, which reveals that eddy current testing would be an efficient non-destructive testing method for the sizing of defects in Inconel welds
International Nuclear Information System (INIS)
Yusa, Noritaka; Janousek, Ladislav; Rebican, Mihai; Chen, Zhenmao; Miya, Kenzo; Machida, Eiji
2004-01-01
This paper evaluates the applicability of eddy current inversion techniques to the sizing of defects in Inconel welds with rough surfaces. For this purpose, a plate Inconel weld specimen, which models the welding of a stub tube in a boiling water nuclear reactor, is fabricated, and artificial notches machined into the specimen. Eddy current inspections using six probes in weld inspection evaluated. It is revealed that if suitable probes are applied, an Inconel weld does not provide large noise signals in eddy current inspections even though the surface of the weld is rough. Finally, reconstruction of the notches are performed using eddy current signals measured with the use of the uniform eddy current probe that showed the best results among the six probes in the inspection. A simplified configuration is proposed in order to consider the complicated configuration of the welded specimen in numerical simulations. While reconstructed profiles of the notches are slightly larger than the true profiles, quite good agreements are obtained in spite of the simple approximation of the configuration, which reveals that eddy current testing would be an efficient non-destructive testing method for the sizing of defects in Inconel welds. (author)
Use of eddy current mixes to solve a weld examination application
International Nuclear Information System (INIS)
Ward, R.C.; LaBoissonniere, A.
1995-01-01
The augmentation of typical nondestructive (i.e., ultrasound) weld inspection techniques by the use of eddy current tools may significantly enhance the quality and reliability of weld inspections. One recent example is the development of an eddy current technique for use in the examination of BWR core shroud welds, where multi-frequency mixes are used to eliminate signals coming from the weld material so that the examination of the heat affected zone is enhanced. An analysis tool most commonly associated with ultrasound examinations, the C-Scan based on gated information, may be implemented with eddy current data to enhance analysis
International Nuclear Information System (INIS)
Hamman, E.; Zorgati, R.
1995-01-01
Eddy current non-destructive testing is used by EDF to detect flaws affecting conductive objects such as steam generator tubes. With a view to obtaining ever more accurate information on equipment integrity, thereby facilitating diagnosis, studies aimed at using measurements to reconstruct an image of the flaw have been proceeding now for about ten years. In this context, our approach to eddy current imaging is based on inverse problem formalism. The direct problem, involving a mathematical model linking measurements provided by a probe with variables characterizing the defect, is dealt with elsewhere. Using the model results, we study the possibility of inverting it, i.e. of reconstructing an image of the flaw from the measurements. We first give an overview of the different inversion techniques, representative of the state of the art and all based on linearization of the inverse problem by means of the Born approximation. The model error resulting from an excessive Born approximation nevertheless severely limits the quantity of the images which can be obtained. In order to counteract this often critical error and extend the eddy current imaging application field, we have to del with the non-linear inverse problem. A method derived from recent research is proposed and implemented to ensure consistency with the exact model. Based on an 'optimization' type approach and provided with a convergence theorem, the method is highly efficient. (authors). 17 refs., 7 figs., 1 append
Design of eddy current probes and signal inversion for non-destructive testing
International Nuclear Information System (INIS)
Ravat, C.
2008-01-01
Non destructive testing is widely used in aerospace industry and nuclear industry. The growing complexity of industrial processes and manufactured parts, the increasing need of safety in service and the will of life span optimization, require more and more complex quality evaluations to be set up. Among the different anomalies to consider, sub-millimetric breaking surface notches have to be subject to special care. Indeed, it often constitutes a start to larger notches, which can cause the destruction of parts. Penetrant testing is nowadays widely used for that kind of defect, owing to its good performances. Nevertheless, it should be eventually dropped because of environmental norms. Among the possible substitution solutions, the use of eddy currents (EC) for conductive parts is a reliable, fast and inexpensive alternative. The study is about the conception and the use of multi-elements EC probe structures featuring microsensors for non destructive testing of surface breaking defects. A methodology has been established in order to develop such structures and to compare their performances within the framework of sub-millimetric surface breaking notch research. These structures has been employed for calibrated notches evaluation with a specific acquisition bench. Original detection and defect characterization algorithms have been designed and implemented on acquired signals. The most efficient structure has been determined, the notch detection quality has been quantified, and the geometric characteristics of notches has been estimated. (author)
International Nuclear Information System (INIS)
Nakamura, Yukiharu; Ozeki, Takahisa
1986-07-01
The finite element circuit theory is extended to the general eddy current problem in a multi-torus system, which consists of various torus conductors and axisymmetric coil systems. The numerical procedures are devised to avoid practical restrictions of computer storage and computing time, that is, the reduction technique of eddy current eigen modes to save storage and the introduction of shape function into the double area integral of mode coupling to save time. The numerical code EDDYMULT based on the theory is developed to use in designing tokamak device from the viewpoints of the evaluation of electromagnetic loading on the device components and the control analysis of tokamak equilibrium. (author)
International Nuclear Information System (INIS)
Emson, C.R.I.
1988-11-01
The paper presents the fifth symposium in the series of Eddy Current Seminars, held in Abingdon, 1988. The meeting included a discussion on three-dimensional eddy current formulations, as well as thirteen contributed papers on computational electromagnetics. Of the thirteen papers, two papers on eddy currents in tokamaks were selected for INIS and indexed separately. (U.K.)
Eddy-current inversion in the thin-skin limit: Determination of depth and opening for a long crack
Burke, S. K.
1994-09-01
A method for crack size determination using eddy-current nondestructive evaluation is presented for the case of a plate containing an infinitely long crack of uniform depth and uniform crack opening. The approach is based on the approximate solution to Maxwell's equations for nonmagnetic conductors in the limit of small skin depth and relies on least-squares polynomial fits to a normalized coil impedance function as a function of skin depth. The method is straightforward to implement and is relatively insensitive to both systematic and random errors. The procedure requires the computation of two functions: a normalizing function, which depends both on the coil parameters and the skin depth, and a crack-depth function which depends only on the coil parameters in addition to the crack depth. The practical perfomance of the method was tested using a set of simulated cracks in the form of electro-discharge machined slots in aluminum alloy plates. The crack depths and crack opening deduced from the eddy-current measurements agree with the actual crack dimensions to within 10% or better. Recommendations concerning the optimum conditions for crack sizing are also made.
Energy Technology Data Exchange (ETDEWEB)
Song, Sung Jin; Lee, Hyang Beom; Kim, Young Hwan [Soongsil Univ., Seoul (Korea, Republic of); Shin, Young Kil [Kunsan Univ., Gunsan (Korea, Republic of)
2004-02-15
Eddy current testing has been widely used for non destructive testing of steam generator tubes. In order to retain reliability in ECT, the following subjects were carried out in this study: numerical modeling and analysis of defects by using BC and RPC probes in SG tube, preparation of absolute coil impedance plane diagram by FEM. Signal interpretation of the eddy current signals obtained from nuclear power plants.
International Nuclear Information System (INIS)
Song, Sung Jin; Lee, Hyang Beom; Kim, Young Hwan; Shin, Young Kil
2004-02-01
Eddy current testing has been widely used for non destructive testing of steam generator tubes. In order to retain reliability in ECT, the following subjects were carried out in this study: numerical modeling and analysis of defects by using BC and RPC probes in SG tube, preparation of absolute coil impedance plane diagram by FEM. Signal interpretation of the eddy current signals obtained from nuclear power plants
Eddy Current Flaw Characterization Using Neural Networks
International Nuclear Information System (INIS)
Song, S. J.; Park, H. J.; Shin, Y. K.
1998-01-01
Determination of location, shape and size of a flaw from its eddy current testing signal is one of the fundamental issues in eddy current nondestructive evaluation of steam generator tubes. Here, we propose an approach to this problem; an inversion of eddy current flaw signal using neural networks trained by finite element model-based synthetic signatures. Total 216 eddy current signals from four different types of axisymmetric flaws in tubes are generated by finite element models of which the accuracy is experimentally validated. From each simulated signature, total 24 eddy current features are extracted and among them 13 features are finally selected for flaw characterization. Based on these features, probabilistic neural networks discriminate flaws into four different types according to the location and the shape, and successively back propagation neural networks determine the size parameters of the discriminated flaw
Eddy current imaging. Simplifying the direct problem. Analysis of a 2D case with formulations
International Nuclear Information System (INIS)
Spineanu, A.; Zorgati, R.
1995-01-01
Eddy current non-destructive testing is used by EDF to detect faults affecting conductive objects such as steam generator tubes. A new technique, known as eddy current imaging, is being developed to facilitate diagnosis in this context. The first stage in this work, discussed in the present paper, consists in solving the direct problem. This entails determining the measurable quantities, on the basis of a thorough knowledge of the material considered. This was done by formulating the direct problem in terms of eddy currents in general 3D geometry context, applying distribution theory and Maxwell equations. Since no direct problem code was available we resorted to simplified situations. Taking care not to interfere with previous developments or those to be attempted in an inversion context, we studied the case of a flaw affecting a 2D structure, illuminated by a plane wave type probe. For this configuration, we studied the exact model and compared results with those of a linearized simplified model. This study emphasizes the ill-posed situation of the eddy current inverse problem related with the severe electromagnetic field attenuation. This means that regularization of the inverse problem, although absolutely necessary, will not be sufficient. Owing to the simplicity of the models available and implemented during the inversion process, processing real data would not yet be possible. We must first focus all our efforts on the direct 3 D problem, in conformity with the requirements of the inverse procedure ad describing a realistic eddy current NDT situation. At the same time, consideration should be given to the design of a specific probe customized for eddy current imaging. (authors). 9 refs., 5 figs., 3 appends
International Nuclear Information System (INIS)
Cecco, V.S.; Van Drunen, G.; Sharp, F.L.
1984-09-01
This report on eddy current testing is divided into three sections: (a) Demonstration of Basic Principles, (b) Practical (Laboratory) Tests and, (c) Typical Certification Questions. It is intended to be used as a supplement to ΣEddy Current Manual, Volume 1Σ (AECL-7523) during CSNDT Foundation Level II and III courses
Experiments with eddy currents: the eddy current brake
International Nuclear Information System (INIS)
Gonzalez, Manuel I
2004-01-01
A moderate-cost experimental setup is presented to help students to understand some qualitative and quantitative aspects of eddy currents. The setup operates like an eddy current brake, a device commonly used in heavy vehicles to dissipate kinetic energy by generating eddy currents. A set of simple experiments is proposed to measure eddy current losses and to relate them to various relevant parameters. Typical results for each of the experiments are presented, and comparisons with theoretical predictions are included. The experiments, which are devoted to first-year undergraduate students, deal also with other pedagogically relevant topics in electricity and magnetism, such as basic laws, electrical measurement techniques, the sources of the magnetic field and others
Remote field eddy current testing
International Nuclear Information System (INIS)
Cheong, Y. M.; Jung, H. K.; Huh, H.; Lee, Y. S.; Shim, C. M.
2001-03-01
The state-of-art technology of the remote field eddy current, which is actively developed as an electromagnetic non-destructive testing tool for ferromagnetic tubes, is described. The historical background and recent R and D activities of remote-field eddy current technology are explained including the theoretical development of remote field eddy current, such as analytical and numerical approach, and the results of finite element analysis. The influencing factors for actual applications, such as the effect of frequency, magnetic permeability, receiving sensitivity, and difficulties of detection and classification of defects are also described. Finally, two examples of actual application, 1) the gap measurement between pressure tubes and calandria tube in CANDU reactor and, 2) the detection of defects in the ferromagnetic heat exchanger tubes, are described. The future research efforts are also included
Eddy currents in accelerator magnets
Moritz, G
2010-01-01
This paper covers the main eddy current effects in accelerator magnets - field modification (time delay and field quality) and resistive power losses. In the first part, starting from the Maxwell equations, a basic understanding of the processes is given and explained with examples of simple geometry and time behaviour. Useful formulas are derived for an analytic estimate of the size of the effects. In the second part the effects in real magnets are analysed and described in comparison with numerical and measured results. Finally, based on the previous parts, design recommendations are given regarding how to minimize eddy current effects.
Eddy current inspection of tubing
International Nuclear Information System (INIS)
Bauza, J. L. R.; Herrero, J.; Diaz, J.
1966-01-01
The Experimental research work carried out to develop a Eddy current testing equipment is described. Search coils with ferrite or air cores were used and the obtained results are discussed. Valuable information was gained from a improved channel in which a direct measure of the defect and the reference signal phase difference is obtained. Artificial defect used to evaluate resolution and sensitivity were produced by electro-machining and mechanical means. Finned SAP tubing was tested in a routine basis with the described equipment and the results plotted. Basic and theoretical considerations on the Eddy current testing technique are given in the last section of this report. (Author)
International Nuclear Information System (INIS)
Cecco, V.S.; Van Drunen, G.; Sharp, F.L.
1983-09-01
This training and reference manual was assembled to provide those involved in eddy current testing with both the fundamental principles of the technique as well as the knowledge to deal with often complicated test results. A non-rigorous approach is used to simplify complex physical phenomena. Emphasis is placed on proper choice of test frequency and signal interpretation. Defect detection and diagnosis receive particular attention. Design and construction of probes are covered extensively since probes play a key role in eddy current testing. The advantages and limitations of various probe types are discussed. Electromagnetic theory, instrumentation, test methods and signal analysis are covered. Simplified derivations of probe response to test parameters are presented to develop a basic understanding of eddy current behaviour. Eddy current signals are presented on impedance plane diagrams throughout the manual since this is the most common display on modern, general purpose instruments. The use of Σphase lagΣ in signal analysis is covered in detail. To supplement theory, practical examples are presented to develop proficiency in performing inspections, and to illustrate how basic principles are applied to diagnose real signals
Eddy current testing, volume 1
International Nuclear Information System (INIS)
Cecco, V.S.; Van Drunen, G.; Sharp, F.L.
1981-11-01
This training and reference manual was assembled to provide those involved in eddy current testing with both the fundamental principles of the technique as well as the knowledge to deal with often complicated test results. A non-rigorous approach is used to simplify complex physical phenomena. Emphasis is placed on proper choice of test frequency and interpretation. Defect detection and diagnosis receive particular attention. Design and construction of probes are covered extensively since probes play a key role in eddy current testing. The advantages and limitations of various probe types are discussed. Electromagnetic theory, instrumentation, test methods and signal analysis are covered. Simplified derivations of probe response to test parameters are presented to develop a basic understanding of eddy current behaviour. Eddy current signals are presented on impedance plane diagrams throughout the manual since this is the most common display on modern, general purpose instruments. The use of 'phase leg' in signal analysis is covered in detail. To supplement theory, practical examples are presented to develop proficiency in performing inspections, and to illustrate how basic principles are applied to diagnose real signals
Quantitative pulsed eddy current analysis
International Nuclear Information System (INIS)
Morris, R.A.
1975-01-01
The potential of pulsed eddy current testing for furnishing more information than conventional single-frequency eddy current methods has been known for some time. However, a fundamental problem has been analyzing the pulse shape with sufficient precision to produce accurate quantitative results. Accordingly, the primary goal of this investigation was to: demonstrate ways of digitizing the short pulses encountered in PEC testing, and to develop empirical analysis techniques that would predict some of the parameters (e.g., depth) of simple types of defect. This report describes a digitizing technique using a computer and either a conventional nuclear ADC or a fast transient analyzer; the computer software used to collect and analyze pulses; and some of the results obtained. (U.S.)
High resolution eddy current microscopy
Lantz, M. A.; Jarvis, S. P.; Tokumoto, H.
2001-01-01
We describe a sensitive scanning force microscope based technique for measuring local variations in resistivity by monitoring changes in the eddy current induced damping of a cantilever with a magnetic tip oscillating above a conducting sample. To achieve a high sensitivity, we used a cantilever with an FeNdBLa particle mounted on the tip. Resistivity measurements are demonstrated on a silicon test structure with a staircase doping profile. Regions with resistivities of 0.0013, 0.0041, and 0.022 Ω cm are clearly resolved with a lateral resolution of approximately 180 nm. For this range of resistivities, the eddy current induced damping is found to depend linearly on the sample resistivity.
DESY: Handling persistent eddy currents
Energy Technology Data Exchange (ETDEWEB)
Anon.
1990-04-15
The vanishing electrical resistance of superconducting coils as well as their ability to provide magnetic fields far beyond those of saturated iron is the main motivation behind the push to use superconducting technology in big new proton accelerators. But this advantage can turn into a drawback at low excitations when the eddy currents - induced in any electromagnet when the field is changed - do not decay, but continue to flow. Preparations for the proton ring of the HERA electron-proton collider nearing completion at the German DESY Laboratory in Hamburg have borne this in mind.
DESY: Handling persistent eddy currents
International Nuclear Information System (INIS)
Anon.
1990-01-01
The vanishing electrical resistance of superconducting coils as well as their ability to provide magnetic fields far beyond those of saturated iron is the main motivation behind the push to use superconducting technology in big new proton accelerators. But this advantage can turn into a drawback at low excitations when the eddy currents - induced in any electromagnet when the field is changed - do not decay, but continue to flow. Preparations for the proton ring of the HERA electron-proton collider nearing completion at the German DESY Laboratory in Hamburg have borne this in mind
Flexible eddy current coil arrays
International Nuclear Information System (INIS)
Krampfner, Y.; Johnson, D.P.
1987-01-01
A novel approach was devised to overcome certain limitations of conventional eddy current testing. The typical single-element hand-wound probe was replaced with a two dimensional array of spirally wound probe elements deposited on a thin, flexible polyimide substrate. This provides full and reliable coverage of the test area and eliminates the need for scanning. The flexible substrate construction of the array allows the probes to conform to irregular part geometries, such as turbine blades and tubing, thereby eliminating the need for specialized probes for each geometry. Additionally, the batch manufacturing process of the array can yield highly uniform and reproducible coil geometries. The array is driven by a portable computer-based eddy current instrument, smartEDDY/sup TM/, capable of two-frequency operation, and offers a great deal of versatility and flexibility due to its software-based architecture. The array is coupled to the instrument via an 80-switch multiplexer that can be configured to address up to 1600 probes. The individual array elements may be addressed in any desired sequence, as defined by the software
Development of Multichannel Eddy Current Testing Instrument
International Nuclear Information System (INIS)
Lee, Hee Jong; Cho, Chan Hee; Nam, Min Woo; Yoon, Byung Sik; Yoo, Hyun Joo
2010-01-01
Four main techniques of electromagnetic testing are used for commercial applications: eddy current testing, alternating current field testing, magnetic flux leakage testing and remote field testing. Eddy current testing is a nondestructive evaluation method, which makes eddy current flow on a specimen by applying driving pulse to eddy current probe coil, by using eddy current testing device, and makes the change of eddy current which is dependently caused by flaws, material characteristics, testing condition, receiving through eddy current, and analyzes material properties, flaws, status on the specimen. Application of EC instrumentation varies widely in industry from the identification of metal heat treatment to the inspection of steam generator tubing in nuclear power plants. In this study, we have designed multichannel EC instrument which can be applicable to the NDE of the tube in heat exchanger for electric power facility, chemistry, and military industry, and finally confirmed the proper function of EC instrumentation
Conformable eddy current array delivery
Summan, Rahul; Pierce, Gareth; Macleod, Charles; Mineo, Carmelo; Riise, Jonathan; Morozov, Maxim; Dobie, Gordon; Bolton, Gary; Raude, Angélique; Dalpé, Colombe; Braumann, Johannes
2016-02-01
The external surface of stainless steel containers used for the interim storage of nuclear material may be subject to Atmospherically Induced Stress Corrosion Cracking (AISCC). The inspection of such containers poses a significant challenge due to the large quantities involved; therefore, automating the inspection process is of considerable interest. This paper reports upon a proof-of-concept project concerning the automated NDT of a set of test containers containing artificially generated AISCCs. An Eddy current array probe with a conformable padded surface from Eddyfi was used as the NDT sensor and end effector on a KUKA KR5 arc HW robot. A kinematically valid cylindrical raster scan path was designed using the KUKA|PRC path planning software. Custom software was then written to interface measurement acquisition from the Eddyfi hardware with the motion control of the robot. Preliminary results and analysis are presented from scanning two canisters.
About the inclusion of eddy currents in micromagnetic computations
International Nuclear Information System (INIS)
Torres, L.; Martinez, E.; Lopez-Diaz, L.; Alejos, O.
2004-01-01
A three-dimensional dynamic micromagnetic model including the effect of eddy currents and its application to magnetization reversal processes in permalloy nanostructures is presented. Model assumptions are tangential current on the nanostructure surface, electrical neutrality and negligible displacement current. The method for solving Landau Lifschitz Gilbert equation coupled to Maxwell equations incorporating the Faraday's law is discussed in detail. The results presented for Permalloy nanocubes of 40 nm side show how the effect of eddy currents can anticipate the magnetization switching. The dependence of the calculations on computational cell size is also reported
Non-Destructive Techniques Based on Eddy Current Testing
García-Martín, Javier; Gómez-Gil, Jaime; Vázquez-Sánchez, Ernesto
2011-01-01
Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future. PMID:22163754
Local eddy current measurements in pulsed fields
Energy Technology Data Exchange (ETDEWEB)
Espina-Hernandez, J.H. [SEPI-Electronica, ESIME-IPN, UPALM Edif. ' Z' . Zacatenco, Mexico DF 07738 (Mexico)], E-mail: jhespina@gmail.com; Groessinger, R. [Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna (Austria); Hallen, J.M. [Departamento de Ingenieria Metalurgica, IPN-ESIQIE, UPALM Edif. 7, Zacatenco, Mexico DF 07738 (Mexico)
2008-07-15
This work presents new eddy current measurements in pulsed fields. A commercial point pick-up coil is used to detect the induction signal along the radius of Cu and Al samples with cylindrical shape and diameters between 5 and 35 mm. Local eddy current measurements were performed on the surface of conducting materials due to the small dimensions of the coil. A simple electrical circuit, used as a model, is proposed to describe the local eddy current effect in pulsed fields. The proposed model allows to calculate the phase shift angle between the signal proportional to eddy currents and the applied external field in a pulsed field magnetometer.
International Nuclear Information System (INIS)
Kincaid, T.G.; McCary, R.O.
1983-01-01
This paper describes theoretical and experimental work directed toward finding the optimum probe dimensions and operating frequency for eddy current detection of half-penny surface cracks in nonmagnetic conducting materials. The study applies to probes which excite an approximately uniform spatial field over the length of the crack at the surface of the material. In practical terms, this means that the probe is not smaller than the crack length in any of its critical dimensions. The optimization of a simple coil probe is first analyzed in detail. It is shown that signal-to-noise ratio and lift-off discrimination are maximized by a pancake coil with mean radius not greater than the crack length, operated at a frequency which gives a skin depth equal to the crack depth. The results obtained for the simple coil are then used as a basis for discussion of the design of coils with ferrite cores and shields, and for the design of recording head type probes
Eddy current analysis in fusion devices
International Nuclear Information System (INIS)
Turner, L.R.
1988-06-01
In magnetic fusion devices, particularly tokamaks and reversed field pinch (RFP) experiments, time-varying magnetic fields are in intimate contact with electrically conducting components of the device. Induced currents, fields, forces, and torques result. This note reviews the analysis of eddy current effects in the following systems: Interaction of a tokamak plasma with the eddy currents in the first wall, blanket, and shield (FWBS) systems; Eddy currents in a complex but two-dimensional vacuum vessel, as in TFTR, JET, and JT-60; Eddy currents in the FWBS system of a tokamak reactor, such as NET, FER, or ITER; and Eddy currents in a RFP shell. The cited studies are chosen to be illustrative, rather than exhaustive. 42 refs
Solving inversion problems with neural networks
Kamgar-Parsi, Behzad; Gualtieri, J. A.
1990-01-01
A class of inverse problems in remote sensing can be characterized by Q = F(x), where F is a nonlinear and noninvertible (or hard to invert) operator, and the objective is to infer the unknowns, x, from the observed quantities, Q. Since the number of observations is usually greater than the number of unknowns, these problems are formulated as optimization problems, which can be solved by a variety of techniques. The feasibility of neural networks for solving such problems is presently investigated. As an example, the problem of finding the atmospheric ozone profile from measured ultraviolet radiances is studied.
Eddy current testing with high penetration
International Nuclear Information System (INIS)
Becker, R.; Kroening, M.
1999-01-01
The low-frequency eddy current testing method is used when penetration into very deep layers is required. The achievable penetration depth is determined among other parameters by the lowest testing frequency that can be realised together with the eddy current sensor. When using inductive sensors, the measuring effect declines proportional to the lowering frequency (induction effect). Further reduction of testing frequency requires other types of sensors, as e.g. the GMR (Giant Magnetic Resistance), which achieves a constant measuring sensitivity down to the steady field. The multi-frequency eddy current testing method MFEC 3 of IZFP described here can be operated using three different scanning frequencies at a time. Two variants of eddy current probes are used in this case. Both have an inductive winding at their emitters, of the type of a measuring probe. The receiver end is either also an inductive winding, or a magnetic field-responsive resistance (GMR). (orig./CB) [de
ECAPS - Eddy Current Approach and Proximity Satellites
National Aeronautics and Space Administration — Multiple, energized coils in a small satellite will generate eddy currents in the skin of the International Space Station (ISS). This will create repulsive forces...
Eddy current testing device using unbalance bridge
International Nuclear Information System (INIS)
Hoshikawa, H.; Koido, J.; Ishibashi, Y.
1976-01-01
An easily readjustable unbalance bridge has been invented and in utilizing the same, an eddy current testing equipment excellent in suppression of the lift-off effect and high in the detection sensitivity has been developed
Thin film eddy current impulse deicer
Smith, Samuel O.; Zieve, Peter B.
1990-01-01
Two new styles of electrical impulse deicers has been developed and tested in NASA's Icing Research Tunnel. With the Eddy Current Repulsion Deicing Boot (EDB), a thin and flexible spiral coil is encapsulated between two thicknesses of elastomer. The coil, made by an industrial printed circuit board manufacturer, is bonded to the aluminum aircraft leading edge. A capacitor bank is discharged through the coil. Induced eddy currents repel the coil from the aluminum aircraft structure and shed accumulated ice. A second configuration, the Eddy Current Repulsion Deicing-Strip (EDS) uses an outer metal erosion strip fastened over the coil. Opposite flowing eddy currents repel the strip and create the impulse deicing force. The outer strip serves as a surface for the collection and shedding of ice and does not require any structural properties. The EDS is suitable for composite aircraft structures. Both systems successfully dispelled over 95 percent of the accumulated ice from airfoils over the range of the FAA icing envelope.
Recognizing limitations in eddy current testing
International Nuclear Information System (INIS)
Van Drunen, G.; Cecco, V.S.
1981-11-01
This paper addresses known limitations and constraints in eddy current nondestructive testing. Incomplete appreciation for eddy current limitations is believed to have contributed to both under-utilization and misapplication of the technique. Neither situation need arise if known limitations are recognized. Some, such as the skin depth effect, are inherent to electromagnetic test methods and define the role of eddy current testing. Others can be overcome with available technology such as surface probes to find circumferential cracks in tubes and magnetic saturation of ferromagnetic alloys to eliminate permeability effects. The variables responsible for limitations in eddy current testing are discussed and where alternative approaches exist, these are presented. Areas with potential for further research and development are also identified
Computation of transient 3-D eddy current in nonmagnetic conductor
International Nuclear Information System (INIS)
Yeh, H.T.
1978-01-01
A numerical procedure was developed to solve transient three-dimensional (3-D) eddy current problems for nonmagnetic conductor. Integral equation formulation in terms of vector potential is used to simplify the matching of boundary conditions. The resulting equations and their numerical approximation were shown to be singular and to require special handling. Several types of symmetries were introduced. They not only reduce the number of algebraic equations to be solved, but also modify the nature of the equations and render them nonsingular. Temporal behavior was obtained with the Runge-Kutta method. The program is tested in several examples of eddy currents for its spatial and temporal profiles, shielding, boundary surface effects, and application of various symmetry options
Eddy currents in pulsed field measurements
International Nuclear Information System (INIS)
Kuepferling, M.; Groessinger, R.; Wimmer, A.; Taraba, M.; Scholz, W.
2002-01-01
Full text: One problem of pulsed field magnetometry is an error in magnetization, which appears in measurements of conducting samples. This error is due to eddy currents induced by a time varying field. To allow predictions how eddy currents exert influence on the hysteresis loop, systematic experimental and theoretical studies of pulsed field measurements of metallic samples were performed. The theoretical studies include analytical calculations as well as numerical ones using a 2D finite element software. In the measurements three physical parameters have been varied: i) the conductivity of the sample by using two different materials, in this case technical Cu and Al ii) size and shape of the sample by using cylinders, spheres and cuboids iii) the pulse duration of the external field by changing the capacitor battery from 8mF ( =9.1ms) to 24mF ( =15.7ms). The time dependence of the external field corresponds with a pulsed damped harmonic oscillation with a maximum value of 5.2T. The samples were studied in the as cast state (after machining) as well as after heat treatment. Theoretical calculations showed not only good agreement with the absolute values of the measured eddy current m agnetization , they also gave an explanation of the shape of the eddy current hysteresis and the dependence of the eddy current 'magnetization' on parameters as pulse duration of the external field and conductivity of the sample. (author)
Experimental modeling of eddy current inspection capabilities
International Nuclear Information System (INIS)
Junker, W.R.; Clark, W.G.
1984-01-01
This chapter examines the experimental modeling of eddy current inspection capabilities based upon the use of liquid mercury samples designed to represent metal components containing discontinuities. A brief summary of past work with mercury modeling and a detailed discussion of recent experiments designed to further evaluate the technique are presented. The main disadvantages of the mercury modeling concept are that mercury is toxic and must be handled carefully, liquid mercury can only be used to represent nonferromagnetic materials, and wetting and meniscus problems can distort the effective size of artificial discontinuities. Artificial discontinuities placed in a liquid mercury sample can be used to represent discontinuities in solid metallic structures. Discontinuity size and type cannot be characterized from phase angle and signal amplitude data developed with a surface scanning, pancake-type eddy current probe. It is concluded that the mercury model approach can greatly enhance the overall understanding and applicability of eddy current inspection techniques
Lateral resolution of eddy current imaging
International Nuclear Information System (INIS)
Hassan, W.; Blodgett, M.; Nagy, P.B.
2002-01-01
Analytical, finite element simulation, and experimental methods were used to investigate the lateral resolution of eddy current microscopy. It was found that the lateral resolution of eddy current imaging is ultimately limited by the probe-coil geometry and dimensions, but both the inspection frequency and the phase angle can be used to optimize the resolution, to some degree, at the expense of sensitivity. Electric anisotropy exhibited by noncubic crystallographic classes of materials such as titanium alloys can play a very similar role in electromagnetic materials characterization of polycrystalline metals to that of elastic anisotropy in ultrasonic materials characterization. Our results demonstrate that eddy current microscopy can be enhanced via a high-resolution, small diameter probe-coil which delivers a unique materials characterization tool well suited for the evaluation of Ti alloys
Transmit-receive eddy current probes
International Nuclear Information System (INIS)
Obrutsky, L.S.; Sullivan, S.P.; Cecco, V.S.
1997-01-01
In the last two decades, due to increased inspection demands, eddy current instrumentation has advanced from single-frequency, single-output instruments to multifrequency, computer-aided systems. This has significantly increased the scope of eddy current testing, but, unfortunately, it has also increased the cost and complexity of inspections. In addition, this approach has not always improved defect detectability or signal-to-noise. Most eddy current testing applications are still performed with impedance probes, which have well known limitations. However, recent research at AECL has led to improved eddy current inspections through the design and development of transmit-receive (T/R) probes. T/R eddy current probes, with laterally displaced transmit and receive coils, present a number of advantages over impedance probes. They have improved signal-to-noise ratio in the presence of variable lift-off compared to impedance probes. They have strong directional properties, permitting probe optimization for circumferential or axial crack detection, and possess good phase discrimination to surface defects. They can significantly increase the scope of eddy current testing permitting reliable detection and sizing of cracks in heat exchanger tubing as well as in welded areas of both ferritic and non-ferromagnetic components. This presentation will describe the operating principles of T/R probes with the help of computer-derived normalized voltage diagrams. We will discuss their directional properties and analyze the advantages of using single and multiple T/R probes over impedance probes for specific inspection cases. Current applications to surface and tube testing and some typical inspection results will be described. (author)
MASCOTTE: analytical model of eddy current signals
International Nuclear Information System (INIS)
Delsarte, G.; Levy, R.
1992-01-01
Tube examination is a major application of the eddy current technique in the nuclear and petrochemical industries. Such examination configurations being specially adapted to analytical modes, a physical model is developed on portable computers. It includes simple approximations made possible by the effective conditions of the examinations. The eddy current signal is described by an analytical formulation that takes into account the tube dimensions, the sensor conception, the physical characteristics of the defect and the examination parameters. Moreover, the model makes it possible to associate real signals and simulated signals
About Eddy Currents in Induction Melting Processes
Directory of Open Access Journals (Sweden)
Gafiţa Nicolae-Bogdan
2008-05-01
Full Text Available In this paper we present a method forcomputing the eddy currents in induction meltingprocesses for non-ferrous alloys. We take intoconsideration the situation when only the crucible ismoving, inside the coils. This fact makes differentialcomputation methods to be hard to apply, because isnecessary to generate a new mesh and a new systemmatrix for every for every new position of the cruciblerelated to the coils. Integral methods cancel thisdrawback because the mesh is generated only for thedomains with eddy currents. For integral methods, themesh and the inductance matrix remain unchangedduring the movement of the crucible; only the free termsof the equation system will change.
Eddy current standards - Cracks versus notches
Hagemaier, D. J.; Collingwood, M. R.; Nguyen, K. H.
1992-10-01
Eddy current tests aimed at evaluating cracks and electron-discharge machined (EDM) notches in 7075-T6 aluminum specimens are described. A comparison of the shape and amplitude of recordings made from both transverse and longitudinal scans of small EDM notches and fatigue cracks showd almost identical results. The signal amplitude and phase angle increased with an increase of EDM notch and crak size. It is concluded that equivalent eddy current results obtained from similar-size surface cracks and notches in aluminum can be used to establish a desired sensitivity level for inspection.
Eddy current inspection of mildly ferromagnetic tubing
International Nuclear Information System (INIS)
Mayo, W.R.; Carter, J.R.
1984-02-01
The past decade has seen the development of eddy current probes for inspection of the mildly ferro-magnetic alloy Monel 400. Due to the rapid advances in permanent magnet technology similar probes have been upgraded to magnetically saturate, and hence inspect, the duplex stainless steel Sandvik 3RE60, which has saturation induction more than twice that of Monel 400. Prototypes of these probes have been tested in three ways: saturation capability, quality of typical eddy current data, and ability to eliminate permeability induced signals. Successful laboratory testing, potential applications, and limitations of these type probes are discussed
A probe for Eddy current inspection devices
International Nuclear Information System (INIS)
1974-01-01
The invention relates to a surface probe for Eddy current inspection devices. According to the invention, said probe comprises two magnetic core windings, with their axes in parallel relationship and at right angles to the surface of the part to be inspected. This can be applied to the nondestructive inspection of reactor components [fr
Eddy current testing of heat exchangers tubes
International Nuclear Information System (INIS)
Gouez, J.F.; Rieusset, A.; Groix, F.
An automatic system for Eddy Current testing of heat exchangers tubes of warships was developed. The advantages are an exposure of the controller limited at the time required to put in place the system and a reduced time of control [fr
Brake Performance Analysis of ABS for Eddy Current and Electrohydraulic Hybrid Brake System
Ren He; Xuejun Liu; Cunxiang Liu
2013-01-01
This paper introduces an eddy current and electro-hydraulic hybrid brake system to solve problems such as wear, thermal failure, and slow response of traditional vehicle brake system. Mathematical model was built to calculate the torque of the eddy current brake system and hydraulic brake system and analyze the braking force distribution between two types of brake systems. A fuzzy controller on personal computer based on LabVIEW and Matlab was designed and a set of hardware in the loop system...
Study, design and manufacture eddy current probes for industry applications
International Nuclear Information System (INIS)
Nguyen Phuc; Nguyen Van Thuy; Vuong Binh Duong; Do Minh Duc; Trinh Dinh Truong; Tran Trong Duc; Do Tung Khanh; Dang Quang Trung
2016-01-01
This study is based on the studying, designing and manufacturing of eddy current probes for industry applications. The main tasks of this study include: i) Describes the overview and classification of eddy current probes (which can be classified into three categories based on the mode of operation: absolute eddy current probe, differential eddy current probe and reflect eddy current probe); ii) Describes the three methods of probe designing and manufacturing (including experimental, analytical and numerical designs); iii) Describes the designing and manufacturing of eddy current probes for industry applications, which based on experimental and analytical methods. Based on this study, we have successfully manufactured some current probes (including absolute eddy current probe, differential eddy current probe and reflect eddy current probe) for surface and tube inspections. (author)
International Nuclear Information System (INIS)
Clark, R.
1989-01-01
The increasing sophistication of eddy current signal interpretation in steam generator tubing has improved capabilities, but has also made the process of analysis more complex and time consuming. Westinghouse has developed an intelligent computerised tool - the IEDA (Intelligent Eddy Current Data Analysis) system, to lighten the load on analysts. Since 1985, 44 plants have been inspected with IEDA, representing over 400,000 tubes. The system has provided a repeatability and a consistency not achieved by human operators. (U.K.)
Workshops and problems for benchmarking eddy current codes
International Nuclear Information System (INIS)
Turner, L.R.; Davey, K.; Ida, N.; Rodger, D.; Kameari, A.; Bossavit, A.; Emson, C.R.I.
1988-02-01
A series of six workshops was held to compare eddy current codes, using six benchmark problems. The problems include transient and steady-state ac magnetic fields, close and far boundary conditions, magnetic and non-magnetic materials. All the problems are based either on experiments or on geometries that can be solved analytically. The workshops and solutions to the problems are described. Results show that many different methods and formulations give satisfactory solutions, and that in many cases reduced dimensionality or coarse discretization can give acceptable results while reducing the computer time required. 13 refs., 1 tab
Thin tube testing by eddy currents
International Nuclear Information System (INIS)
David, Bernard; Pigeon, Michel
1981-01-01
It is often necessary to define test conditions in eddy current testing, in consequence rules and laws allowing a rapid choice of these conditions are welcome. The similarity law, given by Forster, using the reduced frequency f/fg, allows extrapolation of results from an object to one another, if these two objects are similar (i.e. all their dimensions are proportional). In a particular case, often met, a law going further is given to describe, in a sole way, eddy current behaviour using the reduced frequency in all thin tubes (internal to external diameter ratio between 0.85 to 1). For instance working at f/fe=2 defines the same verification leading to identical results, whatever the nature, the diameter or the thickness may be, if the tubes are thin. A diagram is given and a slide-rule, based on this principle, has been realized [fr
Computer modelling of eddy current probes
International Nuclear Information System (INIS)
Sullivan, S.P.
1992-01-01
Computer programs have been developed for modelling impedance and transmit-receive eddy current probes in two-dimensional axis-symmetric configurations. These programs, which are based on analytic equations, simulate bobbin probes in infinitely long tubes and surface probes on plates. They calculate probe signal due to uniform variations in conductor thickness, resistivity and permeability. These signals depend on probe design and frequency. A finite element numerical program has been procured to calculate magnetic permeability in non-linear ferromagnetic materials. Permeability values from these calculations can be incorporated into the above analytic programs to predict signals from eddy current probes with permanent magnets in ferromagnetic tubes. These programs were used to test various probe designs for new testing applications. Measurements of magnetic permeability in magnetically biased ferromagnetic materials have been performed by superimposing experimental signals, from special laboratory ET probes, on impedance plane diagrams calculated using these programs. (author). 3 refs., 2 figs
Pulsed eddy currents: principle and applications
International Nuclear Information System (INIS)
Bernard, A.; Coutanceau, N.
1993-04-01
Eddy currents are widely used as a non destructive testing technique specially for heat exchanger testing. The specificities of pulsed eddy current testing are analyzed in terms of probe design and signal processing. The specific applications are detailed. They are divided in two parts. First part, deals with the two main applications of the high peak energy supplied to the probe. One concerns the design of focused probes used for the detection of small defects in irradiated fuel rods. The other concerns the saturation of ferromagnetic materials in order to test the full thickness of the exchanger tubes. Second part, deals with applications of the wide and low frequency spectrum generated by the pulse source. It enables the testing of thick materials, and the detection of sub-surface defects. It has been tested on austenitic steel (nuclear pressure vessel nozzle), multilayered structures of aluminium alloys (aeronautics) and sleeved structures (nuclear pressure vessel head penetrations through thermal sleeves)
Analysis of eddy current induced in track on medium-low speed maglev train
Li, Guanchun; Jia, Zhen; He, Guang; Li, Jie
2017-06-01
Electromagnetic levitation (EMS) maglev train relies on the attraction between the electromagnets and rails which are mounted on the train to achieve suspension. During the movement, the magnetic field generated by the electromagnet will induce the eddy current in the orbit and the eddy current will weaken the suspended magnetic field. Which leads to the attenuation of the levitation force, the increases of suspension current and the degradation the suspension performance. In this paper, the influence of eddy current on the air gap magnetic field is solved by theoretical analysis, and the correction coefficient of air gap magnetic field is fitted according to the finite element data. The levitation force and current are calculated by the modified formula, and the velocity curves of the levitation force and current are obtained. The results show that the eddy current effect increases the load power by 61.9% in the case of heavy loads.
Eddy Current Signal Analysis for Transmit-Receive Pancake Coil on ECT Array Probe
International Nuclear Information System (INIS)
Lee, Hyang Beom
2006-01-01
In this paper, the eddy current signals come from a pair of transmit-receive (T/R) pancake coil on ECT array Probe are analyzed with the variations of the lift-of and of the distance between transmit and receive coils. To obtain the electromagnetic characteristics of the probes, the governing equation describing the eddy current problems is derived from Maxwell's equation and is solved using three-dimensional finite element method. Eddy current signals from T/R coils on ECT array probe have quite different characteristics compared with ones from impedance coil on rotating pancake coil probe. The results in this paper ran be helpful when the field eddy current signals from ECT array probe are evaluated
Inspection of cup-shaped steel parts from the I.D. side using eddy current
Griffiths, Erick W.; Pearson, Lee H.
2018-04-01
An eddy current method was developed to inspect cup-shaped steel parts from the I.D. side. During the manufacturing process of these parts, a thin Al tape foil is applied to the I.D. side of the part. One of the critical process parameters is that only one foil layer can be applied. An eddy current inspection system was developed to reject parts with more than one foil layer. The Al tape foil is cut to length to fit the inner diameter, however, after application of the foil there is a gap created between the beginning and end of the foil. It was found that this gap interfered with the eddy current inspection causing a false positive indication. To solve this problem a sensor design and data analysis process were developed to overcome the effects of these gaps. The developed system incorporates simultaneous measurements from multiple eddy current sensors and signal processing to achieve a reliable inspection.
Multi-frequency eddy current testing method
International Nuclear Information System (INIS)
Levy, R.; Gallet, G.
1980-01-01
Monitoring by multi-frequency eddy currents has been used since 1975 in French nuclear stations; this method applies perfectly to examinations in non-irradiated surroundings. The restrictions connected with operations in controlled zones (radioactivity) have led to the development of a delayed analysis device which in no way changes the principle of the method, but allows greater flexibility of use by reducing the volume of equipment needed and by limiting the intervention of personnel to a strict minimum [fr
Eddy current inspection of stationary blade rings
International Nuclear Information System (INIS)
Krzywosz, K.J.; Hastings, S.N.
1994-01-01
Stationary turbine blade rings in a US power plant have experienced chloride-induced cracking. Failure analysis determined two types of cracking mechanisms: corrosion fatigue cracking confined to the leading edge of the outer shroud; and stress corrosion cracking present all over the blade surface. Fluorescent dye penetrant is typically used to detect and size cracks. However, it requires cleaning the blade rings by sandblasting to obtain reliable inspection results. Sand blasting in turn requires sealing the lower half of the turbine housing to prevent sand from contaminating the rest of the power plant components. Furthermore, both the penetrant examination and the removal of the sand are time consuming and costly. An alternative NDE technique is desirable which requires no pre-cleaning of the blade and a quick go/no-go inspection with the capability of estimating the crack length. This paper presents an innovative eddy current technique which meets the desired objectives by incorporating the use of specially designed contoured scanners equipped with an array of pancake coils. A set of eddy current pancake coils housed in three different scanners is used to manually scan and inspect the convex side of the stationary blade rings. The pancake coils are operated in a transmit/receive mode using two separate eddy current instruments. This paper presents the inspection concept, including scanner and probe designs, and test results from the various stages of multiple blade rings
Eddy current testing using digital technology
International Nuclear Information System (INIS)
Houseman, H.E.; Lamb, L.T.; Kitson, B.
1985-01-01
Eddy current inspection techniques have been used extensively in industry as an accepted method of non-destructive testing. The application of this technology has proven invaluable for both the control of product quality during the manufacturing process as well as the verification of material integrity throughout the life of a given component. One of the major areas in the power industry where eddy current techniques have been used is for the inspection of installed tubing in various heat exchangers including the steam generators of pressurized water reactor (PWR) nuclear steam supply systems. As increased emphasis is placed upon the operability and safety of these components, test instrumentation has been advanced to improve the efficiency and reliability of inservice inspections. At the same time, plant owners along with manufacturers and inspection service vendors are developing analytical tools for assessing the inspection results. One of the techniques that offers significant potential has been made possible by recent advances in digital technology. The application of digital techniques to the eddy current method offers not only a means to improve the test instrumentation but also an environment whereby other facets of the inservice inspection effort can be enchanced
Problems and limitations of eddy current tube inspection
International Nuclear Information System (INIS)
Ilham Mukriz Zainal Abidin; Khairul Anuar Mohd Salleh; Mohamed Hairul Hasmoni
2003-01-01
Incomplete appreciation of eddy current limitations has contributed to both under-utilization and misapplication of the technique. A brief review on the physical principle of eddy current is presented. Eddy current technique in identifying inhomogeneity in tested tubes is discussed, highlighting its limitation in distinguishing between real pit type defects and other mundane anomalies. The variables responsible for limitation in eddy current tube inspection are discussed and alternative approaches, where they exist, are suggested. (Author)
Determination of linear defect depths from eddy currents disturbances
Ramos, Helena Geirinhas; Rocha, Tiago; Pasadas, Dário; Ribeiro, Artur Lopes
2014-02-01
One of the still open problems in the inspection research concerns the determination of the maximum depth to which a surface defect goes. Eddy current testing being one of the most sensitive well established inspection methods, able to detect and characterize different type of defects in conductive materials, is an adequate technique to solve this problem. This paper reports a study concerning the disturbances in the magnetic field and in the lines of current due to a machined linear defect having different depths in order to extract relevant information that allows the determination of the defect characteristics. The image of the eddy currents (EC) is paramount to understand the physical phenomena involved. The EC images for this study are generated using a commercial finite element model (FLUX). The excitation used produces a uniform magnetic field on the plate under test in the absence of defects and the disturbances due to the defects are compared with those obtained from experimental measurements. In order to increase the limited penetration depth of the method giant magnetoresistors (GMR) are used to lower the working frequency. The geometry of the excitation planar coil produces a uniform magnetic field on an area of around the GMR sensor, inducing a uniform eddy current distribution on the plate. In the presence of defects in the material surface, the lines of currents inside the material are deviated from their uniform direction and the magnetic field produced by these currents is sensed by the GMR sensor. Besides the theoretical study of the electromagnetic system, the paper describes the experiments that have been carried out to support the theory and conclusions are drawn for cracks having different depths.
Essential parameters in eddy current inspection
International Nuclear Information System (INIS)
Stepinski, T.
2000-05-01
Our aim was to qualitatively analyze a number of variables that may affect the result of eddy current (EC) inspection but because of various reasons are not considered as essential in common practice. In the report we concentrate on such variables that can vary during or between inspections but their influence is not determined during routine calibrations. We present a qualitative analysis of the influence of the above-mentioned variables on the ability to detect and size flaws using mechanized eddy current testing (ET). ET employs some type of coil or probe, sensing magnetic flux generated by eddy currents induced in the tested specimen. An amplitude-phase modulated signal (with test frequency f0 ) from the probe is sensed by the EC instrument. The amplitude-phase modulated signal is amplified and demodulated in phase-sensitive detectors removing carrier frequency f0 from the signal. The detectors produce an in-phase and a quadrature component of the signal defining it as a point in the impedance plane. Modern instruments are provided with a screen presenting the demodulated and filtered signal in complex plane. We focus on such issues, related to the EC equipment as, probe matching, distortion introduced by phase discriminators and signal filters, and the influence of probe resolution and lift-off on sizing. The influence of different variables is investigated by means of physical reasoning employing theoretical models and demonstrated using simulated and real EC signals. In conclusion, we discuss the way in which the investigated variables may affect the result of ET. We also present a number of practical recommendations for the users of ET and indicate the areas that are to be further analyzed
Casimir Interaction from Magnetically Coupled Eddy Currents
Intravaia, Francesco; Henkel, Carsten
2009-09-01
We study the quantum and thermal fluctuations of eddy (Foucault) currents in thick metallic plates. A Casimir interaction between two plates arises from the coupling via quasistatic magnetic fields. As a function of distance, the relevant eddy current modes cross over from a quantum to a thermal regime. These modes alone reproduce previously discussed thermal anomalies of the electromagnetic Casimir interaction between good conductors. In particular, they provide a physical picture for the Casimir entropy whose nonzero value at zero temperature arises from a correlated, glassy state.
Eddy current testing of composite pressure vessels
Casperson, R.; Pohl, R.; Munzke, D.; Becker, B.; Pelkner, M.
2018-04-01
The use of composite pressure vessels instead of conventional vessels made of steel or aluminum grew strongly over the last decade. The reason for this trend is the tremendous weight saving in the case of composite vessels. However, the long-time behavior is not fully understood for filling and discharging cycles and creep strength and their influence on the CFRP coating (carbon fiber reinforced plastics) and the internal liner (steel, aluminum, or plastics). The CFRP ensures the pressure resistance while the inner liner is used as a container for liquid or gas. To overcome the missing knowledge of aging, BAM started an internal project to investigate degradation of these material systems. Therefore, applicable testing methods like eddy current testing are needed. Normally, high-frequency eddy current testing (HF-ET, f > 10 MHz) is deployed for CFRP due to its low conductivity of the fiber, which is in the order of 0.01 MS/s, and the capacitive coupling between the fibers. Nevertheless, in some cases conventional ET can be applied. We show a concise summary of studies on the application of conventional ET of composite pressure vessels.
Sukhanov, D. Ya.; Zav'yalova, K. V.
2018-03-01
The paper represents induced currents in an electrically conductive object as a totality of elementary eddy currents. The proposed scanning method includes measurements of only one component of the secondary magnetic field. Reconstruction of the current distribution is performed by deconvolution with regularization. Numerical modeling supported by the field experiments show that this approach is of direct practical relevance.
Scaling relations for eddy current phenomena
International Nuclear Information System (INIS)
Dodd, C.V.; Deeds, W.E.
1975-11-01
Formulas are given for various electromagnetic quantities for coils in the presence of conductors, with the scaling parameters factored out so that small-scale model experiments can be related to large-scale apparatus. Particular emphasis is given to such quantities as eddy current heating, forces, power, and induced magnetic fields. For axially symmetric problems, closed-form integrals are available for the vector potential and all the other quantities obtainable from it. For unsymmetrical problems, a three-dimensional relaxation program can be used to obtain the vector potential and then the derivable quantities. Data on experimental measurements are given to verify the validity of the scaling laws for forces, inductances, and impedances. Indirectly these also support the validity of the scaling of the vector potential and all of the other quantities obtained from it
Eddy current technologies for thick metal structures
International Nuclear Information System (INIS)
Takagi, Toshiyuki; Endo, Hisashi
2004-01-01
One of approach of an eddy current testing (ECT) for thick metal structures is introduced. The detection limit of ECT is capable of enlarging thick more than 10 mm, which is ordinarily about 5 mm, by the design of probe. On the basis of results of numerical analysis, the defect detection in thick and shape is evaluated by the distribution of experimental ECT signals. The problems of ECT for thick metal structures and measures, approach to probe design, the specifications of probe, evaluation of experimental results and defect detection are described. By ECT fast simulator, good slit sharp is simulated in the case of 10 and 20 mm of EDM slit length and 5, 10 and 15 mm of slit height. (S.Y.)
ITOUGH2: Solving TOUGH inverse problems
Energy Technology Data Exchange (ETDEWEB)
Finsterle, S.; Pruess, K. [Lawrence Berkeley Laboratory, CA (United States)
1995-03-01
ITOUGH2 is a program that provides inverse modeling capabilities for the TOUGH2 code. While the main purpose of ITOUGH2 is to estimate two-phase hydraulic properties of calibrating a TOUGH2 model to laboratory or field data, the information obtained by evaluating parameter sensitivities can also be used to optimize the design of an experiment, and to analyze the uncertainty of model predictions. ITOUGH2 has been applied to a number of laboratory and field experiments on different scales. Three examples are discussed in this paper, demonstrating the code`s capability to support test design, data analysis, and model predictions for a variety of TOUGH problems.
Workshops and problems for benchmarking eddy current codes
Energy Technology Data Exchange (ETDEWEB)
Turner, L.R.; Davey, K.; Ida, N.; Rodger, D.; Kameari, A.; Bossavit, A.; Emson, C.R.I.
1988-08-01
A series of six workshops was held in 1986 and 1987 to compare eddy current codes, using six benchmark problems. The problems included transient and steady-state ac magnetic fields, close and far boundary conditions, magnetic and non-magnetic materials. All the problems were based either on experiments or on geometries that can be solved analytically. The workshops and solutions to the problems are described. Results show that many different methods and formulations give satisfactory solutions, and that in many cases reduced dimensionality or coarse discretization can give acceptable results while reducing the computer time required. A second two-year series of TEAM (Testing Electromagnetic Analysis Methods) workshops, using six more problems, is underway. 12 refs., 15 figs., 4 tabs.
Workshops and problems for benchmarking eddy current codes
International Nuclear Information System (INIS)
Turner, L.R.; Davey, K.; Ida, N.; Rodger, D.; Kameari, A.; Bossavit, A.; Emson, C.R.I.
1988-08-01
A series of six workshops was held in 1986 and 1987 to compare eddy current codes, using six benchmark problems. The problems included transient and steady-state ac magnetic fields, close and far boundary conditions, magnetic and non-magnetic materials. All the problems were based either on experiments or on geometries that can be solved analytically. The workshops and solutions to the problems are described. Results show that many different methods and formulations give satisfactory solutions, and that in many cases reduced dimensionality or coarse discretization can give acceptable results while reducing the computer time required. A second two-year series of TEAM (Testing Electromagnetic Analysis Methods) workshops, using six more problems, is underway. 12 refs., 15 figs., 4 tabs
Forward transformation for high resolution eddy current tomography using whitney elements
International Nuclear Information System (INIS)
Szewczyk, R.; Salach, J.; Nowicki, M.; Ruokolainen, J.; Raback, P.
2014-01-01
Tomographic methods are intensively developed field of non-destructive testing. The main advantage of this type of NDT method is 3D information concerning the shape of the discontinuities in investigated material. On the other hand, the most common tomography method utilizing X-rays creates the significant risks typical to X-ray technique. As a result, Xray tomography is difficult to use in industry. Introduced to the industry in 2007, the eddy current tomography is safe and cost effective. However, in opposite to X-ray tomography, eddy current tomography requires sophisticated and time consuming inverse transformation creating 2D or 3D view of discontinuities. For this reason solutions presented previously are focused on 2D inverse transformation and exhibit limited resolution. For eddy current tomography, the forward tomographic transformation is most important, which is the base of inverse transformation. This paper presents the novel, fast and cost-effective solution utilizing Whitney elements method for such forward transformation. As a result, new possibilities of development in the area of high resolution 3D eddy current tomography are created. (authors)
EDGE EFFECT INFLUENCE TO REFLECTED IMPEDANCE OF EDDY-CURRENT PROBE
Directory of Open Access Journals (Sweden)
О. Закревський
2012-04-01
Full Text Available This work is dedicated to solve analytically the edge effect Eddy-Current Probe (ECP problem which helpto carry out mathematical research the edge effect influence to ECP precision and sensitivity ultrasonictransducer mechanical amplitude oscillation measurement mathematical research, pointed to cylindricalconductive objects radius control possibility with superimposed ECP.
Eddy current inspection on heat exchanger tubes - problems and limitations
International Nuclear Information System (INIS)
Ilham Mukriz; Zainal Abidin Mohamed; Hairul Hasmoni Khairul Anuar; Mohd Salleh; Mahmood Dollah
2005-01-01
This paper focus on problems associated to eddy current inspection of heat exchanger tubes. A brief review on heat exchanger design and operation is presented. Eddy current technique in identifying inhomogeneity in tested tubes is discussed, highlighting its limitation in distinguishing between real pit type defects and other mundane anomalies. The limitation of the eddy current probe and equipment pertinent to the inspection are identified and areas of improvement are discussed. (Author)
Eddy current detection of corrosion damage in heat exchanger tubes
International Nuclear Information System (INIS)
Van Drunen, G.; Cecco, V.S.; Carter, J.R.
1980-05-01
Eddy current is often the most effective nondestructive test method available for in-service inspection of small bore tubing in heat exchangers. The basic principles, advantages and shortcomings of the technique are outlined. Typical eddy current indications from corrosion-related defects such as stress corrosion cracks, pitting and tube denting under support plates are presented. Eddy current signals from features such as magnetite deposits and ferromagnetic inclusions which might be mistaken for defects are also discussed. (auth)
Eddy current seminar, 24-26 Mar 1986
International Nuclear Information System (INIS)
Emson, C.R.I.
1986-06-01
The paper concerns the Eddy Current Seminars, held at the Rutherford Appleton Laboratory, United Kingdom, March 1986. Twenty two papers were presented on eddy current phenomena, and two of the papers are indexed separately. The first deals with a finite difference scheme for time dependent eddy currents in Tokamaks, the second is an analysis of the FELIX experiments with cantilevered beams and hollow cylinders. (UK)
Eddy Current Assessment of Engineered Components Containing Nanofibers
Ko, Ray T.; Hoppe, Wally; Pierce, Jenny
2009-03-01
The eddy current approach has been used to assess engineered components containing nanofibers. Five specimens with different programmed defects were fabricated. A 4-point collinear probe was used to verify the electrical resistivity of each specimen. The liftoff component of the eddy current signal was used to test two extreme cases with different nano contents. Additional eddy current measurements were also used in detecting a missing nano layer simulating a manufacturing process error. The results of this assessment suggest that eddy current liftoff measurement can be a useful tool in evaluating the electrical properties of materials containing nanofibers.
Eddy current characterization of small cracks using least square support vector machine
Chelabi, M.; Hacib, T.; Le Bihan, Y.; Ikhlef, N.; Boughedda, H.; Mekideche, M. R.
2016-04-01
Eddy current (EC) sensors are used for non-destructive testing since they are able to probe conductive materials. Despite being a conventional technique for defect detection and localization, the main weakness of this technique is that defect characterization, of the exact determination of the shape and dimension, is still a question to be answered. In this work, we demonstrate the capability of small crack sizing using signals acquired from an EC sensor. We report our effort to develop a systematic approach to estimate the size of rectangular and thin defects (length and depth) in a conductive plate. The achieved approach by the novel combination of a finite element method (FEM) with a statistical learning method is called least square support vector machines (LS-SVM). First, we use the FEM to design the forward problem. Next, an algorithm is used to find an adaptive database. Finally, the LS-SVM is used to solve the inverse problems, creating polynomial functions able to approximate the correlation between the crack dimension and the signal picked up from the EC sensor. Several methods are used to find the parameters of the LS-SVM. In this study, the particle swarm optimization (PSO) and genetic algorithm (GA) are proposed for tuning the LS-SVM. The results of the design and the inversions were compared to both simulated and experimental data, with accuracy experimentally verified. These suggested results prove the applicability of the presented approach.
Some thoughts on an eddy current septum magnet
International Nuclear Information System (INIS)
Halbach, K.
1995-01-01
It is the purpose of this report to describe the thinking and work that went into thoroughly understanding, a specific eddy current septum magnet that will be used in the APS and needs ''fixing.'' The goal is to go beyond mere qualitative understanding and carry the analysis far enough to recognize the real problems of this magnet and to develop the tools to solve them. While it would be very tempting to write this report in very general terms, it would be very difficult to achieve complete generality, and one would risk losing the focus on this specific magnet that needs to have an improved performance. The discussion contains, however, so many generally useful concepts and procedures that it might further be useful for designers of other eddy current septum magnets both at the APS and elsewhere. Since it is necessary not only to have a deep qualitative understanding of several aspects of this type of magnet, but also to quantitatively assess what has to be done to achieve the desired performance, fairly heavy use of mathematical tools was made. In doing so it became clear that the extensive use of these tools is essential not only for this purpose, but also to get the required good qualitative understanding of the device. For instance, it turns out that in this particular instance, an important part of the underlying physics does not become clear until one seems to run into what one might consider, at first, a mathematical problem, whose resolution is not clear until one has found the solution, which then seems ''obvious.'' Even though iron in the septum has a nonlinear relationship between B and H, assuming a constant permeability is sufficient to obtain the information needed to develop a sufficient understanding of the magnet to make some crucial decisions
Automatic analysis of signals during Eddy currents controls
International Nuclear Information System (INIS)
Chiron, D.
1983-06-01
A method and the corresponding instrument have been developed for automatic analysis of Eddy currents testing signals. This apparatus enables at the same time the analysis, every 2 milliseconds, of two signals at two different frequencies. It can be used either on line with an Eddy Current testing instrument or with a magnetic tape recorder [fr
Signal processing of eddy current three-dimensional maps
International Nuclear Information System (INIS)
Birac, C.; David, D.; Lamant, D.
1987-01-01
Digital processing of eddy current three-dimensional maps improves accuracy of detection: flattening, filtering, computing deconvolution, mapping new variables,.., give new possibilities for difficult test problems. With simulation of defects, probes, probe travels, it is now possible to compute new eddy current processes, without machining defects or building probes
Regularization method for solving the inverse scattering problem
International Nuclear Information System (INIS)
Denisov, A.M.; Krylov, A.S.
1985-01-01
The inverse scattering problem for the Schroedinger radial equation consisting in determining the potential according to the scattering phase is considered. The problem of potential restoration according to the phase specified with fixed error in a finite range is solved by the regularization method based on minimization of the Tikhonov's smoothing functional. The regularization method is used for solving the problem of neutron-proton potential restoration according to the scattering phases. The determined potentials are given in the table
Abu-Nabah, Bassam A.
Recent research results indicated that eddy current conductivity measurements can be exploited for nondestructive evaluation of near-surface residual stresses in surface-treated nickel-base superalloy components. Most of the previous experimental studies were conducted on highly peened (Almen 10-16A) specimens that exhibit harmful cold work in excess of 30% plastic strain. Such high level of cold work causes thermo-mechanical relaxation at relatively modest operational temperatures; therefore the obtained results were not directly relevant to engine manufacturers and end users. The main reason for choosing peening intensities in excess of recommended normal levels was that in low-conductivity engine alloys the eddy current penetration depth could not be forced below 0.2 mm without expanding the measurements above 10 MHz which is beyond the operational range of most commercial eddy current instruments. As for shot-peened components, it was initially felt that the residual stress effect was more difficult to separate from cold work, texture, and inhomogeneity effects in titanium alloys than in nickel-base superalloys. In addition, titanium alloys have almost 50% lower electric conductivity than nickel-base superalloys; therefore require proportionally higher inspection frequencies, which was not feasible until our recent breakthrough in instrument development. Our work has been focused on six main aspects of this continuing research, namely, (i) the development of an iterative inversion technique to better retrieve the depth-dependent conductivity profile from the measured frequency-dependent apparent eddy current conductivity (AECC), (ii) the extension of the frequency range up to 80 MHz to better capture the peak compressive residual stress in nickel-base superalloys using a new eddy current conductivity measuring system, which offers better reproducibility, accuracy and measurement speed than the previously used conventional systems, (iii) the lift-off effect on
Solving of L0 norm constrained EEG inverse problem.
Xu, Peng; Lei, Xu; Hu, Xiao; Yao, Dezhong
2009-01-01
l(0) norm is an effective constraint used to solve EEG inverse problem for a sparse solution. However, due to the discontinuous and un-differentiable properties, it is an open issue to solve the l(0) norm constrained problem, which is usually instead solved by using some alternative functions like l(1) norm to approximate l(0) norm. In this paper, a continuous and differentiable function having the same form as the transfer function of Butterworth low-pass filter is introduced to approximate l(0) norm constraint involved in EEG inverse problem. The new approximation based approach was compared with l(1) norm and LORETA solutions on a realistic head model using simulated sources. The preliminary results show that this alternative approximation to l(0) norm is promising for the estimation of EEG sources with sparse distribution.
International Nuclear Information System (INIS)
Reboud, Ch.
2006-09-01
Eddy current testing (ECT) technique is widely used in industrial fields such as iron and steel industry. Dedicated simulation tools provide a great assistance for the optimisation of ECT processes. CEA and the Vallourec Research Center have collaborated in order to develop a simulation tool of ECT of tubes. The volume integral method has been chosen for the resolution of Maxwell equations in a stratified medium, in order to get accurate results with a computation time short enough to carry out optimisation or inversion procedures. A fast model has been developed for the simulation of ECT of non magnetic tubes using specific external probes. New flaw geometries have been modelled: holes and notches with flat bottom. Validations of the developments, which have been integrated to the CIVA platform, have been carried out using experimental data recorded in laboratory conditions and in. industrial conditions, successively. The integral equations derived are solved using the Galerkin variant of the method of moments with pulse functions as projection functions. In order to overcome some memory limitations, other projection functions have been considered. A new discretization scheme based on non-uniform B-Splines of degree 1 or 2 has been implemented, which constitutes an original contribution to the existing literature. The decrease of the mesh size needed to get a given accuracy on the result may lead to the simulation of more complex ECT configurations. (author)
Investigating the computer analysis of eddy current NDT data
International Nuclear Information System (INIS)
Brown, R.L.
1979-01-01
The objective of this activity was to investigate and develop techniques for computer analysis of eddy current nondestructive testing (NDT) data. A single frequency commercial eddy current tester and a precision mechanical scanner were interfaced with a PDP-11/34 computer to obtain and analyze eddy current data from samples of 316 stainless steel tubing containing known discontinuities. Among the data analysis techniques investigated were: correlation, Fast Fourier Transforms (FFT), clustering, and Adaptive Learning Networks (ALN). The results were considered encouraging. ALN, for example, correctly identified 88% of the defects and non-defects from a group of 153 signal indications
Eddy current analysis by the finite element circuit method
International Nuclear Information System (INIS)
Kameari, A.; Suzuki, Y.
1977-01-01
The analysis of the transient eddy current in the conductors by ''Finite Element Circuit Method'' is developed. This method can be easily applied to various geometrical shapes of thin conductors. The eddy currents on the vacuum vessel and the upper and lower support plates of JT-60 machine (which is now being constructed by Japan Atomic Energy Research Institute) are calculated by this method. The magnetic field induced by the eddy current is estimated in the domain occupied by the plasma. And the force exerted to the vacuum vessel is also estimated
Improved eddy-current inspection for steam generator tubing
International Nuclear Information System (INIS)
Dodd, C.V.; Pate, J.R.; Allen, J.D. Jr.
1989-01-01
Computer programs have been written to allow the analysis of different types of eddy-current probes and their performance under different steam generator test conditions. The probe types include the differential bobbin probe, the absolute bobbin probe, the pancake probe and the reflection probe. The generator test conditions include tube supports, copper deposits, magnetite deposits, denting, wastage, pitting, cracking and IGA. These studies are based mostly on computed values, with the limited number of test specimens available used to verify the computed results. The instrument readings were computed for a complete matrix of the different test conditions, and then the test conditions determined as a function of the readings by a least-squares technique. A comparison was made of the errors in fit and instrument drift for the different probe types. The computations of the change in instrument reading due to the defects have led to an ''inversion'' technique in which the defect properties can be computed from the instrument readings. This has been done both experimentally and analytically for each of these probe types. 3 refs., 13 figs., 1 tab
Eddy current testing system for bottom mounted instrumentation welds - 15206
International Nuclear Information System (INIS)
Kobayashi, N.; Ueno, S.; Suganuma, N.; Oodake, T.; Maehara, T.; Kasuya, T.; Ichikawa, H.
2015-01-01
We have demonstrated the scanning of eddy current testing (ECT) probe on the welds area including the nozzle, the J-welds and the buildup welds of the Bottom Mounted Instrumentation (BMI) mock-up using the developed ECT system and procedure. It is difficult to scan the probe on the BMI welds area because the area has a complex curved surface shape and narrow spaces. We made the space coordinates and the normal vectors on the scanning points as the scanning trajectory of probe on the welds area based on the measured results of welds surface shape on the mock-up. The multi-axis robot was used to scan the probe on the welds surface. Each motion axis position of the robot corresponding to each scanning point was calculated by the inverse kinematic algorithm. The BMI mock-up test was performed using the cross coil probe in the differential mode. The artificial stress corrosion cracking and the electrical discharge machining slits given on the mock-up surface were detected. The results show that the ECT can detect a defect of approximately 2.3 mm in length, 0.5 mm in depth and 0.2 mm in width for the BMI welds. From the output voltage of single coil, we estimated that the average and the maximum probe tilt angles on the mock-up surface under scanning were 2.6 degrees and 8.5 degrees, respectively
Eddy current testing system for bottom mounted instrumentation welds
Directory of Open Access Journals (Sweden)
Kobayashi Noriyasu
2015-01-01
Full Text Available The capability of eddy current testing (ECT for the bottom mounted instrumentation (BMI weld area of reactor vessel in a pressurized water reactor was demonstrated by the developed ECT system and procedure. It is difficult to position and move the probe on the BMI weld area because the area has complexly curved surfaces. The space coordinates and the normal vectors at the scanning points were calculated as the scanning trajectory of probe based on the measured results of surface shape on the BMI mock-up. The multi-axis robot was used to move the probe on the mock-up. Each motion-axis position of the robot corresponding to each scanning point was calculated by the inverse kinematic algorithm. In the mock-up test, the probe was properly contacted with most of the weld surfaces. The artificial stress corrosion cracking of approximately 6 mm in length and the electrical-discharge machining slit of 0.5 mm in length, 1 mm in depth and 0.2 mm in width given on the weld surface were detected. From the probe output voltage, it was estimated that the average probe tilt angle on the surface under scanning was 2.6°.
Theoretical study of a flat eddy current probe
International Nuclear Information System (INIS)
Bouchard, A.; Dumont-Fillon, J.; Labbe, G.
1976-01-01
A mathematical model for the computation of the impedance of an eddy current probe has been determined in the case of flat product testing. Various applications are discussed with particular emphasis on ferromagnetic materials [fr
IVA Ultrasonic and Eddy Current NDE for ISS
National Aeronautics and Space Administration — The project intends to develop a combined Ultrasonic and Eddy Current nondestructive evaluation (NDE) instrument for IVA use on ISS. A suite of IVA and EVA NDE...
Eddy current testing probe with dual half-cylindrical coils
Bae, Byung-Hoon; Choi, Jung-Mi; Kim, Soo-Yong
2000-02-01
We have developed a new eddy current probe composed of a dual half-cylindrical (2HC) coil as an exciting coil and a sensing coil that is placed in the small gap of the 2HC coil. The 2HC coil induces a linear eddy current on the narrow region within the target medium. The magnitude of eddy current has a maximum peak with the narrow width, underneath the center of the exciting 2HC coil. Because of the linear eddy current, the probe can be used to detect not only the existence of a crack but also its direction in conducting materials. Using specimen with a machined crack, and varying the exciting frequency from 0.5 to 100 kHz, we investigated the relationships between the direction of crack and the output voltage of the sensing coil.
Foam-machining tool with eddy-current transducer
Copper, W. P.
1975-01-01
Three-cutter machining system for foam-covered tanks incorporates eddy-current sensor. Sensor feeds signal to numerical controller which programs rotational and vertical axes of sensor travel, enabling cutterhead to profile around tank protrusions.
International Nuclear Information System (INIS)
Shen, Y.; Lo, C. C. H.; Frishman, A. M.; Lee, C.; Nakagawa, N.
2007-01-01
This paper describes an eddy current model-based method for inverting near-surface conductivity deviation profiles of surface treated materials from swept-high frequency eddy current (SHFEC) data. This work forms part of our current research directed towards the development of an electromagnetic nondestructive technique for assessing residual stress of shot-peened superalloy components. The inversion procedure is based on the use of a parameterized function to describe the near-surface conductivity as a function of depth for a shot-peened surface, and the laterally uniform multi-layer theory of Cheng, Dodd and Deeds to calculate the resulting coil impedance deviations. The convergence of the inversion procedure has been tested against synthesized eddy current data. As a demonstration, the conductivity deviation profiles of a series of Inconel 718 specimens, shot peened at various Almen intensities, have been obtained by inversion. Several consistency tests were conducted to examine the reliability of the inverted conductivity profiles. The results show that conductivity deviation profiles can be reliably determined from SHFEC data within the accuracy of the current measurement system
Remote field eddy current testing of ferromagnetic tubes
International Nuclear Information System (INIS)
David, B.
1990-01-01
In order to test ferromagnetic tubes using internal probes, Intercontrole and the CEA have carried out theoretical and experimental works and developed a method to adapt the Remote Field Eddy Current technique which has been known and used for 30 years now. This document briefly recalls the basic principles of the Remote Field Eddy Current technique, the various steps of the works carried out and mainly describes examples of field inspection of ferromagnetic tubes and pipes [fr
System for evaluating weld quality using eddy currents
Todorov, Evgueni I.; Hay, Jacob
2017-12-12
Electromagnetic and eddy current techniques for fast automated real-time and near real-time inspection and monitoring systems for high production rate joining processes. An eddy current system, array and method for the fast examination of welds to detect anomalies such as missed seam (MS) and lack of penetration (LOP) the system, array and methods capable of detecting and sizing surface and slightly subsurface flaws at various orientations in connection with at least the first and second weld pass.
Eddy current analysis by BEM utilizing loop electric and surface magnetic currents as unknowns
International Nuclear Information System (INIS)
Ishibashi, Kazuhisa
2002-01-01
The surface integral equations whose unknowns are the surface electric and magnetic currents are widely used in eddy current analysis. However, when the skin depth is thick, computational error is increased especially in obtaining electromagnetic fields near the edge of the conductor. In order to obtain the electromagnetic field accurately, we propose an approach to solve surface integral equations utilizing loop electric and surface magnetic currents as unknowns. (Author)
Coupled circuit numerical analysis of eddy currents in an open MRI system
Akram, Md. Shahadat Hossain; Terada, Yasuhiko; Keiichiro, Ishi; Kose, Katsumi
2014-08-01
We performed a new coupled circuit numerical simulation of eddy currents in an open compact magnetic resonance imaging (MRI) system. Following the coupled circuit approach, the conducting structures were divided into subdomains along the length (or width) and the thickness, and by implementing coupled circuit concepts we have simulated transient responses of eddy currents for subdomains in different locations. We implemented the Eigen matrix technique to solve the network of coupled differential equations to speed up our simulation program. On the other hand, to compute the coupling relations between the biplanar gradient coil and any other conducting structure, we implemented the solid angle form of Ampere’s law. We have also calculated the solid angle for three dimensions to compute inductive couplings in any subdomain of the conducting structures. Details of the temporal and spatial distribution of the eddy currents were then implemented in the secondary magnetic field calculation by the Biot-Savart law. In a desktop computer (Programming platform: Wolfram Mathematica 8.0®, Processor: Intel(R) Core(TM)2 Duo E7500 @ 2.93 GHz; OS: Windows 7 Professional; Memory (RAM): 4.00 GB), it took less than 3 min to simulate the entire calculation of eddy currents and fields, and approximately 6 min for X-gradient coil. The results are given in the time-space domain for both the direct and the cross-terms of the eddy current magnetic fields generated by the Z-gradient coil. We have also conducted free induction decay (FID) experiments of eddy fields using a nuclear magnetic resonance (NMR) probe to verify our simulation results. The simulation results were found to be in good agreement with the experimental results. In this study we have also conducted simulations for transient and spatial responses of secondary magnetic field induced by X-gradient coil. Our approach is fast and has much less computational complexity than the conventional electromagnetic numerical
Vessel eddy current characteristics in SST-1 tokamak
Energy Technology Data Exchange (ETDEWEB)
Jana, Subrata; Pradhan, Subrata, E-mail: pradhan@ipr.res.in; Dhongde, Jasraj; Masand, Harish
2016-11-15
Highlights: • Eddy current distribution in the SST-1 vacuum vessel. • Circuit model analysis of eddy current. • A comparison of the field lines with and without the plasma column in identical conditions. • The influence of eddy current in magnetic NULL dynamics. - Abstract: Eddy current distribution in the vacuum vessel of the Steady state superconducting (SST-1) tokamak has been determined from the experimental data obtained using an array of internal voltage loops (flux loop) installed inside the vacuum vessel. A simple circuit model has been employed. The model takes into account the geometric and constructional features of SST-1 vacuum vessel. SST-1 vacuum vessel is a modified ‘D’ shaped vessel having major axis of 1.285 m and minor axis of 0.81 m and has been manufactured from non-magnetic stainless steel. The Plasma facing components installed inside the vacuum vessel are graphite blocks mounted on Copper Chromium Zirconium (CuCrZr) heat sink plates on inconel supports. During discharge of the central solenoid, eddy currents get generated in the vacuum vessel and passive supports on it. These eddy currents influence the early magnetic NULL dynamics and plasma break-down and start-up characteristics. The computed results obtained from the model have been benchmarked against experimental data obtained in large number of SST-1 plasma shots. The results are in good agreement. Once bench marked, the calculated eddy current based on flux loop signal and circuit equation model has been extended to the reconstruction of the overall B- field contours of SST-1 tokamak in the vessel region. A comparison of the field lines with and without the plasma column in identical conditions of the central solenoid and equilibrium field profiles has also been done with an aim to quantify the diagnostics responses in vacuum shots.
Eddy Current Sensing of Torque in Rotating Shafts
Varonis, Orestes J.; Ida, Nathan
2013-12-01
The noncontact torque sensing in machine shafts is addressed based on the stress induced in a press-fitted magnetoelastic sleeve on the shaft and eddy current sensing of the changes of electrical conductivity and magnetic permeability due to the presence of stress. The eddy current probe uses dual drive, dual sensing coils whose purpose is increased sensitivity to torque and decreased sensitivity to variations in distance between probe and shaft (liftoff). A mechanism of keeping the distance constant is also employed. Both the probe and the magnetoelastic sleeve are evaluated for performance using a standard eddy current instrument. An eddy current instrument is also used to drive the coils and analyze the torque data. The method and sensor described are general and adaptable to a variety of applications. The sensor is suitable for static and rotating shafts, is independent of shaft diameter and operational over a large range of torques. The torque sensor uses a differential eddy current measurement resulting in cancellation of common mode effects including temperature and vibrations.
Brake Performance Analysis of ABS for Eddy Current and Electrohydraulic Hybrid Brake System
Directory of Open Access Journals (Sweden)
Ren He
2013-01-01
Full Text Available This paper introduces an eddy current and electro-hydraulic hybrid brake system to solve problems such as wear, thermal failure, and slow response of traditional vehicle brake system. Mathematical model was built to calculate the torque of the eddy current brake system and hydraulic brake system and analyze the braking force distribution between two types of brake systems. A fuzzy controller on personal computer based on LabVIEW and Matlab was designed and a set of hardware in the loop system was constructed to validate and analyze the performance of the hybrid brake system. Through lots of experiments on dry and wet asphalt roads, the hybrid brake system achieves perfect performance on the experimental bench, the hybrid system reduces abrasion and temperature of the brake disk, response speed is enhanced obviously, fuzzy controller keeps high utilization coefficient due to the optimal slip ratio regulation, and the total brake time has a smaller decrease than traditional hydraulic brake system.
Investigation on a new inducer of pulsed eddy current thermography
Directory of Open Access Journals (Sweden)
Min He
2016-09-01
Full Text Available In this paper, a new inducer of pulsed eddy current thermography (PECT is presented. The use of the inducer can help avoid the problem of blocking the infrared (IR camera’s view in eddy current thermography technique. The inducer can also provide even heating of the test specimen. This paper is concerned with the temperature distribution law around the crack on a specimen when utilizing the new inducer. Firstly, relative mathematical models are provided. In the following section, eddy current distribution and temperature distribution around the crack are studied using the numerical simulation method. The best separation distance between the inducer and the specimen is also determined. Then, results of temperature distribution around the crack stimulated by the inducer are gained by experiments. Effect of current value on temperature rise is studied as well in the experiments. Based on temperature data, temperature features of the crack are discussed.
EFFICIENCY OF METAL SCRAP SEPARATION IN EDDY CURRENT SEPARATOR
Directory of Open Access Journals (Sweden)
Gordan Bedeković
2008-11-01
Full Text Available Eddy-current separation is most often method used for the recovery of non-ferrous metals (Al, Cu, Zn, Pb from solid wastes and also for separating non-ferrous metals from each other. The feed material comes to rotary drum and magnetic field by belt conveyer. The changing magnetic field induce eddy currents in conductive (metallic particles. Because interaction between this currents and the magnetic field electrodynamic forces will act on conductive particles. Therefore the trajectories of conductive particles will be different from the trajectories of the non-conductive ones. Separation is a result of the combined actions of several forces (electrodynamic, gravitational and frictional. The paper presents results of aluminium recovery from mixture of metallic particles in eddy current separator. Testing were conducted under field condition. Results shows that is possible achieve recovery of 99 % and concentrate quality of 89 % of aluminium (the paper is published in Croatian.
Eddy Current Testing for Detecting Small Defects in Thin Films
Obeid, Simon; Tranjan, Farid M.; Dogaru, Teodor
2007-03-01
Presented here is a technique of using Eddy Current based Giant Magneto-Resistance sensor (GMR) to detect surface and sub-layered minute defects in thin films. For surface crack detection, a measurement was performed on a copper metallization of 5-10 microns thick. It was done by scanning the GMR sensor on the surface of the wafer that had two scratches of 0.2 mm, and 2.5 mm in length respectively. In another experiment, metal coatings were deposited over the layers containing five defects with known lengths such that the defects were invisible from the surface. The limit of detection (resolution), in terms of defect size, of the GMR high-resolution Eddy Current probe was studied using this sample. Applications of Eddy Current testing include detecting defects in thin film metallic layers, and quality control of metallization layers on silicon wafers for integrated circuits manufacturing.
Sizing Performance of the Newly Developed Eddy Current System
Energy Technology Data Exchange (ETDEWEB)
Cho, Chan Hee; Lee, Hee Jong; Yoo, Hyun Ju; Moon, Gyoon Young; Lee, Tae Hoon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)
2013-10-15
This paper describes the comparison results of sizing performance for two systems. The KHNP developed a new eddy current testing system for the inspection of steam generator tubing in domestic nuclear power plants. The equivalency assessment of the newly developed system with the EPRI-qualified system was already carried out. In this paper, the comparisons of depth-sizing performance for the artificial flaws between two systems were performed. The results show that the newly developed system is in good agreement with the qualified system. Therefore, it is expected that the newly developed eddy current system can be used for the inspection of steam generator tubing in nuclear power plants. There are some non-destructive examination (NDE) methods for the inspection of components in nuclear power plants, such as ultrasonic, radiographic, eddy current testing, etc. The eddy current testing is widely used for the inspection of steam generator (SG) tubing because it offers a relatively low cost approach for high speed, large scale testing of metallic materials in high pressure and temperature engineering systems. The Korea Hydro and Nuclear Power Co., Ltd. (KHNP) developed an eddy current testing system for the inspection of steam generator tubing in nuclear power plants. This system includes not only hardware but software such as the frequency generator and data acquisition-analysis program. The foreign eddy current system developed by ZETEC is currently used for the inspection of steam generator tubing in domestic nuclear power plants. The equivalency assessment between two systems was already carried out in accordance with the EPRI steam generator examination guidelines.
Eddy current NDE performance demonstrations using simulation tools
International Nuclear Information System (INIS)
Maurice, L.; Costan, V.; Guillot, E.; Thomas, P.
2013-01-01
To carry out performance demonstrations of the Eddy-Current NDE processes applied on French nuclear power plants, EDF studies the possibility of using simulation tools as an alternative to measurements on steam generator tube mocks-up. This paper focuses on the strategy led by EDF to assess and use code C armel3D and Civa, on the case of Eddy-Current NDE on wears problem which may appear in the U-shape region of steam generator tubes due to the rubbing of anti-vibration bars.
Application of Eddy Currents in Medicine and their Modelling
International Nuclear Information System (INIS)
Krawczyk, A.; Wiak, S.; Zyss, T.; Sikora, R.
1998-01-01
The paper deals with the problems of interactions between the electromagnetic field and biological material, in particular the problem of eddy currents in human tissues and cells induced there for medical purposes, and the mathematical modeling of the phenomenon. The diagnostic and therapeutic effects of eddy currents are discussed and the advantages and drawbacks of these effects are given. A deeper analysis is devoted to the problem of transcranial magnetic stimulation (TMS) which is used in psychiatry as the treatment in depressive psychosis. (author)
Eddy current effect in soft magnetic backlayer for PMR media
International Nuclear Information System (INIS)
Tanaka, T.; Yamamoto, S.; Kurisu, H.; Matsuura, M.
2005-01-01
Flux density distributions in the recording layer and soft magnetic backlayer of a perpendicular magnetic recording medium were calculated up to 5 GHz using a three-dimensional finite element method electromagnetic field analysis simulator, where eddy current effects in the high-frequency recording process were considered. It is presented that the flux density distribution in a recording layer hardly depends on the eddy current effect, although flux density distribution in a soft magnetic backlayer changes depending on the recording frequency and resistivity of the soft magnetic backlayer
Device for ultrasonic and eddy current testing of bolts
International Nuclear Information System (INIS)
Hromek, J.; Kaspar, P.
1989-01-01
The device provides pivoting fitting of the bolt of a WWER reactor steam generator while ultrasonic and eddy current probes are brought near. The bolt under study is clamped between a drive funnel and a securing cone. The eddy current probes are adjusted using guide arms to the point requested and are fitted over the bolt such as for their thread segments to engage the bolt thread. The ultrasonic transducers are then adjusted to the required point. The device can be used for testing bolts of a thread size from M54x5 and a maximum length of 600 mm. (J.B.). 1 fig
Defect detection in conducting materials using eddy current testing techniques
Directory of Open Access Journals (Sweden)
Brauer Hartmut
2014-01-01
Full Text Available Lorentz force eddy current testing (LET is a novel nondestructive testing technique which can be applied preferably to the identification of internal defects in nonmagnetic moving conductors. The LET is compared (similar testing conditions with the classical eddy current testing (ECT. Numerical FEM simulations have been performed to analyze the measurements as well as the identification of internal defects in nonmagnetic conductors. The results are compared with measurements to test the feasibility of defect identification. Finally, the use of LET measurements to estimate of the electrical conductors under test are described as well.
A hybrid algorithm for solving inverse problems in elasticity
Directory of Open Access Journals (Sweden)
Barabasz Barbara
2014-12-01
Full Text Available The paper offers a new approach to handling difficult parametric inverse problems in elasticity and thermo-elasticity, formulated as global optimization ones. The proposed strategy is composed of two phases. In the first, global phase, the stochastic hp-HGS algorithm recognizes the basins of attraction of various objective minima. In the second phase, the local objective minimizers are closer approached by steepest descent processes executed singly in each basin of attraction. The proposed complex strategy is especially dedicated to ill-posed problems with multimodal objective functionals. The strategy offers comparatively low computational and memory costs resulting from a double-adaptive technique in both forward and inverse problem domains. We provide a result on the Lipschitz continuity of the objective functional composed of the elastic energy and the boundary displacement misfits with respect to the unknown constitutive parameters. It allows common scaling of the accuracy of solving forward and inverse problems, which is the core of the introduced double-adaptive technique. The capability of the proposed method of finding multiple solutions is illustrated by a computational example which consists in restoring all feasible Young modulus distributions minimizing an objective functional in a 3D domain of a photo polymer template obtained during step and flash imprint lithography.
Modelling and simulation of eddy current non-destructive testing
International Nuclear Information System (INIS)
Mansir, H.; Burais, N.; Nicolas, A.
1986-01-01
This paper presents the practical configuration for detecting cracks in conducting materials by eddy current non destructive testing. An electromagnetic field formulation is proposed using Maxwell's relations. Geometrical and physical properties of the crack are taken into account by several models, particularly with a new finite element called ''crack element''. Modelisation is applied to sensor impedance calculation with classical numerical methods [fr
Apparatus For Eddy-Current Inspection Of Bolts
Amos, Jay M.
1994-01-01
Eddy-current apparatus for inspection of bolts, studs, and other threaded fasteners detects flaws in threads, shanks, and head fillets. With help of apparatus, technician quickly inspects fasteners of various dimensions. Accommodates fasteners with diameters from 0.190 in. to 1 in. and with lengths up to 5 in. Basic design modified to accommodate fasteners of other sizes.
Eddy current technique applied to automated tube profilometry
International Nuclear Information System (INIS)
Dobbeni, D.; Melsen, C. van
1982-01-01
The use of eddy current methods in the first totally automated pre-service inspection of the internal diameter of PWR steam generator tubes is described. The technique was developed at Laborelec, the Belgian Laboratory of the Electricity Supply Industry. Details are given of the data acquisition system and of the automated manipulator. Representative tube profiles are illustrated. (U.K.)
A Laboratory Activity on the Eddy Current Brake
Molina-Bolivar, J. A.; Abella-Palacios, A. J.
2012-01-01
The aim of this paper is to introduce a simple and low-cost experimental setup that can be used to study the eddy current brake, which considers the motion of a sliding magnet on an inclined conducting plane in terms of basic physical principles. We present a set of quantitative experiments performed to study the influence of the geometrical and…
Principles and applications of multiplane pulsed eddy currents
International Nuclear Information System (INIS)
David, B.; Champonnois, F.; Joffre, F.
1989-01-01
A pulsed device using eddy currents, producing 8 shape signals on the screen like a sine wave system, has been developed. The method has been applied to the well-known problem of defects in stainless claddings of PWR reactor vessels
Integral Model of Eddy Currents in Nonmagnetic Structures
Czech Academy of Sciences Publication Activity Database
Doležel, Ivo; Karban, P.
2004-01-01
Roč. 4, č. 3 (2004), s. 5-12 ISSN 1335-8243 R&D Projects: GA ČR GA102/03/0047 Keywords : magnetic field * eddy currents * integral equations Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Subminiature eddy current transducers for studying boride coatings
Dmitriev, S. F.; Ishkov, A. V.; Malikov, V. N.; Sagalakov, A. M.
2016-07-01
Strengthening of parts and units of machines, increased reliability and longer service life is an important task of modern mechanical engineering. The main objects of study in the work were selected steel 65G and 50HGA, wear-resistant boride coatings ternary system Fe-B-Fe n B which were investigated by scanning electron microscopy and eddy-current nondestructive methods.
Review on solving the inverse problem in EEG source analysis
Directory of Open Access Journals (Sweden)
Fabri Simon G
2008-11-01
Full Text Available Abstract In this primer, we give a review of the inverse problem for EEG source localization. This is intended for the researchers new in the field to get insight in the state-of-the-art techniques used to find approximate solutions of the brain sources giving rise to a scalp potential recording. Furthermore, a review of the performance results of the different techniques is provided to compare these different inverse solutions. The authors also include the results of a Monte-Carlo analysis which they performed to compare four non parametric algorithms and hence contribute to what is presently recorded in the literature. An extensive list of references to the work of other researchers is also provided. This paper starts off with a mathematical description of the inverse problem and proceeds to discuss the two main categories of methods which were developed to solve the EEG inverse problem, mainly the non parametric and parametric methods. The main difference between the two is to whether a fixed number of dipoles is assumed a priori or not. Various techniques falling within these categories are described including minimum norm estimates and their generalizations, LORETA, sLORETA, VARETA, S-MAP, ST-MAP, Backus-Gilbert, LAURA, Shrinking LORETA FOCUSS (SLF, SSLOFO and ALF for non parametric methods and beamforming techniques, BESA, subspace techniques such as MUSIC and methods derived from it, FINES, simulated annealing and computational intelligence algorithms for parametric methods. From a review of the performance of these techniques as documented in the literature, one could conclude that in most cases the LORETA solution gives satisfactory results. In situations involving clusters of dipoles, higher resolution algorithms such as MUSIC or FINES are however preferred. Imposing reliable biophysical and psychological constraints, as done by LAURA has given superior results. The Monte-Carlo analysis performed, comparing WMN, LORETA, sLORETA and SLF
Research on Defects Inspection of Solder Balls Based on Eddy Current Pulsed Thermography
Directory of Open Access Journals (Sweden)
Xiuyun Zhou
2015-10-01
Full Text Available In order to solve tiny defect detection for solder balls in high-density flip-chip, this paper proposed feasibility study on the effect of detectability as well as classification based on eddy current pulsed thermography (ECPT. Specifically, numerical analysis of 3D finite element inductive heat model is generated to investigate disturbance on the temperature field for different kind of defects such as cracks, voids, etc. The temperature variation between defective and non-defective solder balls is monitored for defects identification and classification. Finally, experimental study is carried on the diameter 1mm tiny solder balls by using ECPT and verify the efficacy of the technique.
Numeral eddy current sensor modelling based on genetic neural network
International Nuclear Information System (INIS)
Yu Along
2008-01-01
This paper presents a method used to the numeral eddy current sensor modelling based on the genetic neural network to settle its nonlinear problem. The principle and algorithms of genetic neural network are introduced. In this method, the nonlinear model parameters of the numeral eddy current sensor are optimized by genetic neural network (GNN) according to measurement data. So the method remains both the global searching ability of genetic algorithm and the good local searching ability of neural network. The nonlinear model has the advantages of strong robustness, on-line modelling and high precision. The maximum nonlinearity error can be reduced to 0.037% by using GNN. However, the maximum nonlinearity error is 0.075% using the least square method
Eddy current calculations for the Tore Supra toroidal field magnet
International Nuclear Information System (INIS)
Blum, J.
1983-01-01
An outline is given of the calculation of the eddy currents in the magnetic structures of a Tokamak, which can be assimilated to thin conductors, so that the three-dimensional problem can be reduced mathematically to a two-dimensional one, the variables being two orthogonal coordinates of the considered surface. A finite element method has been used in order to treat the complicated geometry of the set of the 18 toroidal field coil casings and mechanical structures of Tore Supra. This eddy current code has been coupled with an axisymmetric equilibrium code in order to simulate typical phases of a Tokamak discharge (plasma current rise, additional heating, disruption, cleaning discharge) and the losses in the toroidal field magnet have thus been calculated. (author)
Eddy current probe development based on a magnetic sensor array
International Nuclear Information System (INIS)
Vacher, F.
2007-06-01
This research deals with in the study of the use of innovating magnetic sensors in eddy current non destructive inspection. The author reports an analysis survey of magnetic sensor performances. This survey enables the selection of magnetic sensor technologies used in non destructive inspection. He presents the state-of-the-art of eddy current probes exploiting the qualities of innovating magnetic sensors, and describes the methods enabling the use of these magnetic sensors in non destructive testing. Two main applications of innovating magnetic sensors are identified: the detection of very small defects by means of magneto-resistive sensors, and the detection of deep defects by means of giant magneto-impedances. Based on the use of modelling, optimization, signal processing tools, probes are manufactured for these both applications
Progress realized by numerized Eddy current checking-chains
International Nuclear Information System (INIS)
Guerin, F.; Blanchet, A.
1985-01-01
Until the last ten years , the tubes of the Steam Generators of the Nuclear Stations were inspected by means of Eddy Current with analogical checkings-chains. HBS Company has perfected a numerized checking-chain allowing transmission up to 300 m of the E.C. signals. In a near future, it will be then possible to do periodical inspections of Steam Generators from cabins located out of the reactor building [fr
The TS 600: automatic control system for eddy currents
International Nuclear Information System (INIS)
Poulet, J.P.
1986-10-01
In the scope of fabrication and in service inspection of the PWR steam generator tubing bendle, FRAMATOME developed an automatic Eddy Current testing system: TS600. Based on a mini-computer, TS600 allows to digitize, to store and to process data in various ways, so it is possible to perform several kinds of inspection: conventional inservice inspection, roll area profilometry...... TS600 can also be used to develop new methods of examination [fr
Multifrequency eddy current testing of helical tubes of steam generators
International Nuclear Information System (INIS)
Pigeon, M.; David, B.
1983-06-01
In the event of a water-sodium reaction in a steam-generator of a fast breeder reactor, it is necessary to test the tubes close to the leak to evaluate the damage. In SUPERPHENIX, the tubes are about 100m long and are coiled on a dead body. This report describes the equipment and the technic to test such tubes with multifrequency eddy current technics [fr
The integral equation method applied to eddy currents
International Nuclear Information System (INIS)
Biddlecombe, C.S.; Collie, C.J.; Simkin, J.; Trowbridge, C.W.
1976-04-01
An algorithm for the numerical solution of eddy current problems is described, based on the direct solution of the integral equation for the potentials. In this method only the conducting and iron regions need to be divided into elements, and there are no boundary conditions. Results from two computer programs using this method for iron free problems for various two-dimensional geometries are presented and compared with analytic solutions. (author)
Eddy current modeling in linear and nonlinear multifilamentary composite materials
Menana, Hocine; Farhat, Mohamad; Hinaje, Melika; Berger, Kevin; Douine, Bruno; Lévêque, Jean
2018-04-01
In this work, a numerical model is developed for a rapid computation of eddy currents in composite materials, adaptable for both carbon fiber reinforced polymers (CFRPs) for NDT applications and multifilamentary high temperature superconductive (HTS) tapes for AC loss evaluation. The proposed model is based on an integro-differential formulation in terms of the electric vector potential in the frequency domain. The high anisotropy and the nonlinearity of the considered materials are easily handled in the frequency domain.
Eddy current testing system for bottom mounted instrumentation welds
Kobayashi Noriyasu; Ueno Souichi; Suganuma Naotaka; Oodake Tatsuya; Maehara Takeshi; Kasuya Takashi; Ichikawa Hiroya
2015-01-01
The capability of eddy current testing (ECT) for the bottom mounted instrumentation (BMI) weld area of reactor vessel in a pressurized water reactor was demonstrated by the developed ECT system and procedure. It is difficult to position and move the probe on the BMI weld area because the area has complexly curved surfaces. The space coordinates and the normal vectors at the scanning points were calculated as the scanning trajectory of probe based on the measured results of surface shape on th...
Performance demonstration requirements for eddy current steam generator tube inspection
International Nuclear Information System (INIS)
Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.
1992-10-01
This paper describes the methodology used for developing performance demonstration tests for steam generator tube eddy current (ET) inspection systems. The methodology is based on statistical design principles. Implementation of a performance demonstration test based on these design principles will help to ensure that field inspection systems have a high probability of detecting and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented. Probability of detection and flaw sizing tests are described
Surface inspection technique with an eddy current testing array probe
International Nuclear Information System (INIS)
Nishimizu, Akira; Endo, Hisashi; Tooma, Masahiro; Otani, Kenichi; Ouchi, Hirofumi; Yoshida, Isao; Nonaka, Yoshio
2010-01-01
An eddy current testing (ECT) system has been developed for inspecting weld surfaces of components in the reactor pressure vessel of nuclear plants. The system can be applied to curved surfaces with an ECT array probe, it can discriminate flaws from other signal factors by using a combination of arrayed coils signal-phase. The system is applied to a mock-up of core internal components and the signal discrimination using the signal-phase clearly separated flaw and noise signals. (author)
Sensitivity analysis of eddy current sensors using computational simulation
Neugebauer, Reimund; Drossel, W.-G.; Mainda, P.; Roscher, H.-J.; Wolf, K.; Kroschk, M.
2011-01-01
Eddy current sensors can detect the position and movement of metal parts without direct contact. The magnetic fields of these sensors can penetrate protective metal enclosures when designed and applied appropriately. Thus particularly robust solutions for industrial applications are possible, e.g. tracking objects electrically like conductive or ferromagnetic work pieces (device currently being tested) during a treatment process under difficult production conditions. The disadvantage of a tes...
Eddy current testing probe optimization using a parallel genetic algorithm
Directory of Open Access Journals (Sweden)
Dolapchiev Ivaylo
2008-01-01
Full Text Available This paper uses the developed parallel version of Michalewicz's Genocop III Genetic Algorithm (GA searching technique to optimize the coil geometry of an eddy current non-destructive testing probe (ECTP. The electromagnetic field is computed using FEMM 2D finite element code. The aim of this optimization was to determine coil dimensions and positions that improve ECTP sensitivity to physical properties of the tested devices.
Three-axis orthogonal transceiver coil for eddy current sounding
Sukhanov, D.; Zavyalova, K.; Goncharik, M.
2017-08-01
We propose the new structure of three-axis transceiver magnetic-induction coil for eddy current probing. Due to the orientation of the coils, the direct signal from the transmitting coil to the receiving coil is minimized, which provided a high dynamic range. Sensitivity in all directions is provided by combining coils of different orientations. Numerical simulation and experimental studies of such a system have been carried out and confirmed the applicability of the proposed method and the mathematical model.
Assessment of defects in ferromagnetic metals with eddy currents
Oaten, Susan Rosemary
1989-01-01
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. A study was made to identify and size surface breaking defects in ferromagnetic materials with eddy currents, whilst eliminating unwanted signals due to changes in magnetic permeability and probe lift-off. The former was overcome by the use of high frequencies and the latter by utilising the lift-off to characterise the defects. The lift- off or "touch" method was shown to be advantageous in ...
Validating eddy current array probes for inspecting steam generator tubes
International Nuclear Information System (INIS)
Sullivan, S.P.; Cecco, V.S.; Obrutsky, L.S.
1997-01-01
A CANDU nuclear reactor was shut down for over one year because steam generator (SG) tubes had failed with outer diameter stress-corrosion cracking (ODSCC) in the U-bend section. Novel, single-pass eddy current transmit-receive probes, denoted as C3, were successful in detecting all significant cracks so that the cracked tubes could be plugged and the unit restarted. Significant numbers of tubes with SCC were removed from a SG in order to validate the results of the new probe. Results from metallurgical examinations were used to obtain probability-of-detection (POD) and sizing accuracy plots to quantify the performance of this new inspection technique. Though effective, the above approach of relying on tubes removed from a reactor is expensive, in terms of both economic and radiation-exposure costs. This led to a search for more affordable methods to validate inspection techniques and procedures. Methods are presented for calculating POD curves based on signal-to-noise studies using field data. Results of eddy current scans of tubes with laboratory-induced ODSCC are presented with associated POD curves. These studies appear promising in predicting realistic POD curves for new inspection technologies. They are being used to qualify an improved eddy current array probe in preparation for field use. (author)
Eddy current test of fin tubes for a heat exchanger
International Nuclear Information System (INIS)
KIm, Young Joo; Lee, Se Kyung; Chung, Min Hwa
1992-01-01
Eddy current probes were designed for the test of fin tubes. Fin tubes, often used for heat exchangers, have uneven outer and inner surfaces to enhance the heat emission. The surface roughness make it difficult to detect flaws employing eddy current test(ECT). In order to overcome the difficulties we performed two types of works, one is the delopment of ECT probes, and the other is the signal processing including fast Fourier transform and digital filtering. In the development of ECT probes, we adopted empirical design method. Our ECT probes for fin tubes are inside diameter type. And we are specially concerned about geometric features such as the widths of the coils composing an ECT probe. We fabricated four probes with various coil widths. Eddy current test was performed using those ECT probes on specimens with artificial flaws. After analyzing the output signals, we found that, in order for the effective testing, the width of a coil should be determined considering the pitch of the fins of a tube. And we also learned that the frequency filtering could improve the s/n ratio.
Eddy current inspection of steam generator tubing plugs
International Nuclear Information System (INIS)
Cullen, W.K.
1990-01-01
In response to the issues raised regarding the integrity of nuclear steam generator tubing plugs manufactured from certain heats of Inconel 600, Westinghouse engineers have developed, qualified and implemented an eddy current inspection system for the in-place assessment of these plugs. The heart of the system is a robotic and effector which delivers an eddy current sensor through the reduced diameter of the plug expander and actuates the coil to physical contact with the expanded inside bore of the plug. Once deployed, the eddy current sensor is rotated along a helical path to produce a detailed scan of the plug surface above the final position of the expander. This testing produces an isometric display of degradation due to primary water stress corrosion cracking, on the inside surface of the plug. To date, successful inspections have been conducted at two nuclear units with two different robotic delivery systems. While designed specifically for mechanical plugs with a bottle bore cavity, the inspection system can also be used for expanded straight bore plugs. Details of the inspection system along with a discussion of qualification activities and actual field results are presented in this paper
Two numerical methods for the solution of two-dimensional eddy current problems
International Nuclear Information System (INIS)
Biddlecombe, C.S.
1978-07-01
A general method for the solution of eddy current problems in two dimensions - one component of current density and two of magnetic field, is reported. After examining analytical methods two numerical methods are presented. Both solve the two dimensional, low frequency limit of Maxwell's equations for transient eddy currents in conducting material, which may be permeable, in the presence of other non-conducting permeable material. Both solutions are expressed in terms of the magnetic vector potential. The first is an integral equation method, using zero order elements in the discretisation of the unknown source regions. The other is a differential equation method, using a first order finite element mesh, and the Galerkin weighted residual procedure. The resulting equations are solved as initial-value problems. Results from programs based on each method are presented showing the power and limitations of the methods and the range of problems solvable. The methods are compared and recommendations are made for choosing between them. Suggestions are made for improving both methods, involving boundary integral techniques. (author)
Characterization of irradiated fuel rods using pulsed eddy current techniques
International Nuclear Information System (INIS)
Martin, M.R.; Francis, W.C.
1975-11-01
A number of irradiated fuel rods and unfueled zircaloy cladding tubes (''water tubes'') were obtained from the Saxton reactor through arrangements with the Westinghouse Electric Corporation for use in subsequent irradiation effects and fuel behavior programs. A comprehensive nondestructive and corroborative destructive characterization program was undertaken on these fuel rods and tubes by ANC to provide baseline data on their characteristics prior to further testing and for comparison against post-post data. This report deals primarily with one portion of the NDT program performed remotely in the hot cells. The portion of interest in this paper is the pulsed eddy current inspection used in the nondestructive phase of the work. 6 references
Electromagnetic modeling method for eddy current signal analysis
International Nuclear Information System (INIS)
Lee, D. H.; Jung, H. K.; Cheong, Y. M.; Lee, Y. S.; Huh, H.; Yang, D. J.
2004-10-01
An electromagnetic modeling method for eddy current signal analysis is necessary before an experiment is performed. Electromagnetic modeling methods consists of the analytical method and the numerical method. Also, the numerical methods can be divided by Finite Element Method(FEM), Boundary Element Method(BEM) and Volume Integral Method(VIM). Each modeling method has some merits and demerits. Therefore, the suitable modeling method can be chosen by considering the characteristics of each modeling. This report explains the principle and application of each modeling method and shows the comparison modeling programs
Eddy current system for inspection of train hollow axles
Energy Technology Data Exchange (ETDEWEB)
Chady, Tomasz; Psuj, Grzegorz; Sikora, Ryszard; Kowalczyk, Jacek; Spychalski, Ireneusz [Department of Electrical and Computer Engineering, Faculty of Electrical Engineering, West Pomeranian University of Technology, Szczecin (Poland)
2014-02-18
The structural integrity of wheelsets used in rolling stock is of great importance to the safety. In this paper, electromagnetic system with an eddy current transducer suitable for the inspection of hollow axles have been presented. The transducer was developed to detect surface braking defects having depth not smaller than 0.5 mm. Ultrasound technique can be utilized to inspect the whole axle, but it is not sufficiently sensitive to shallow defects located close to the surface. Therefore, the electromagnetic technique is proposed to detect surface breaking cracks that cannot be detected by ultrasonic technique.
Eddy current calculations for the tore supra tokamak
International Nuclear Information System (INIS)
Blum, J.; Dupas, L.; Leloup, C.; Thooris, B.
1983-01-01
This paper deals with the calculation of the eddy currents in the structures of a Tokamak, which can be assimilated to thin conductors, so that the three-dimensional problem can be reduced mathematically to a two-dimensional one, the variables being two orthogonal coordinates of the considered surface. A variational formulation of the problem in terms of the electric vector potential is then given and a finite element method has been used, which enables to treat the complicated geometry of the toroidal field magnet, the mechanical structures and the vacuum vessels of Tore Supra
Determining Confounding Sensitivities In Eddy Current Thin Film Measurements
Energy Technology Data Exchange (ETDEWEB)
Gros, Ethan; Udpa, Lalita; Smith, James A.; Wachs, Katelyn
2016-07-01
Determining Confounding Sensitivities In Eddy Current Thin Film Measurements Ethan Gros, Lalita Udpa, Electrical Engineering, Michigan State University, East Lansing MI 48824 James A. Smith, Experiment Analysis, Idaho National Laboratory, Idaho Falls ID 83415 Eddy current (EC) techniques are widely used in industry to measure the thickness of non-conductive films on a metal substrate. This is done using a system whereby a coil carrying a high-frequency alternating current is used to create an alternating magnetic field at the surface of the instrument's probe. When the probe is brought near a conductive surface, the alternating magnetic field will induce ECs in the conductor. The substrate characteristics and the distance of the probe from the substrate (the coating thickness) affect the magnitude of the ECs. The induced currents load the probe coil affecting the terminal impedance of the coil. The measured probe impedance is related to the lift off between coil and conductor as well as conductivity of the test sample. For a known conductivity sample, the probe impedance can be converted into an equivalent film thickness value. The EC measurement can be confounded by a number of measurement parameters. It is the goal of this research to determine which physical properties of the measurement set-up and sample can adversely affect the thickness measurement. The eddy current testing is performed using a commercially available, hand held eddy current probe (ETA3.3H spring loaded eddy probe running at 8 MHz) that comes with a stand to hold the probe. The stand holds the probe and adjusts the probe on the z-axis to help position the probe in the correct area as well as make precise measurements. The signal from the probe is sent to a hand held readout, where the results are recorded directly in terms of liftoff or film thickness. Understanding the effect of certain factors on the measurements of film thickness, will help to evaluate how accurate the ETA3.3H spring
Surface flaw evaluation by vectorized eddy current testing image
International Nuclear Information System (INIS)
Endo, Hisashi; Takagi, Toshiyuki
2006-01-01
A method of eddy current testing (ECT) data mapping for surface breaking evaluation is studied. The multicoil ECT probe utilized in this paper consists of Transmit-Receive (TR) type sensors as array elements to obtain the information on crack directions. Switching two directional scans, U- and T- modes, gives two-dimensional vector mapping as ECT images. The ECT signals of the TR type sensor also give the information on crack directions from their variation displayed on the complex number plane. Extracting a complex number component of the signals makes it possible to visualize directions of numerically simulated proximate EDM slits. (author)
Development of an automatized device for eddy current testing
International Nuclear Information System (INIS)
David, B.; Benoist, B.; Champonnois, F.; Viard, J.
1990-01-01
To improve performances in eddy current studies, several tools were developed in the Saclay Laboratory: - ELEFANT is a very flexible software which allows a rapid creation of new NDT applications, preserving anytime a full compatibility between computers, applications, data... used under the same ELEFANT controlkey. - Modulo'STA is a modular hardware designed to be the flexible interface between the probe and the computer, driving the measurement, the probe movement... - rotating EC probes with local rotation facilities allow the control of very long steam generator tubes, even bent [fr
International Nuclear Information System (INIS)
Lavrentyev, Anton I.; Stucky, Paul A.; Veronesi, William A.
2000-01-01
Shot peening is a well-known method for extending the fatigue life of metal components by introducing compressive residual stresses near their surfaces. The capability to nondestructively evaluate the near surface residual stress would greatly aid the assurance of proper fatigue life in shot-peened components. This paper presents preliminary results from a feasibility study examining the use of ultrasonic and eddy current NDE methods for residual stress measurement in components where the stress has been introduced by shot peening. With an ultrasonic method, a variation of ultrasonic surface wave speed with shot peening intensity was measured. Near surface conductivity was measured by eddy current methods. Since the effective penetration depth of both methods employed is inversely related to the excitation frequency, by making measurements at different frequencies, each method has the potential to provide the stress-depth profile. Experiments were conducted on aluminum specimens (alloy 7075-T7351) peened within the Almen peening intensity range of 4C to 16C. The experimental results obtained demonstrate a correlation between peening intensity and Rayleigh wave velocity and between peening intensity and conductivity. The data suggests either of the methods may be suitable, with limitations, for detecting unsatisfactory levels of shot peening. Several factors were found to contribute to the measured responses: surface roughness, near surface plastic deformation (cold work) and residual stress. The contribution of each factor was studied experimentally. The feasibility of residual stress determination from the measured data is discussed
Influence of magnet eddy current on magnetization characteristics of variable flux memory machine
Yang, Hui; Lin, Heyun; Zhu, Z. Q.; Lyu, Shukang
2018-05-01
In this paper, the magnet eddy current characteristics of a newly developed variable flux memory machine (VFMM) is investigated. Firstly, the machine structure, non-linear hysteresis characteristics and eddy current modeling of low coercive force magnet are described, respectively. Besides, the PM eddy current behaviors when applying the demagnetizing current pulses are unveiled and investigated. The mismatch of the required demagnetization currents between the cases with or without considering the magnet eddy current is identified. In addition, the influences of the magnet eddy current on the demagnetization effect of VFMM are analyzed. Finally, a prototype is manufactured and tested to verify the theoretical analyses.
Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear
DEFF Research Database (Denmark)
Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue
2012-01-01
In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...... current analysis. The model takes the eddy current effect of PMs into account in determination of the magnetic field in the air-gap and in the magnet regions. The eddy current losses generated in the magnets are properly interpreted. Design improvements for reducing the eddy current losses are suggested...
Children's strategies to solving additive inverse problems: a preliminary analysis
Ding, Meixia; Auxter, Abbey E.
2017-03-01
Prior studies show that elementary school children generally "lack" formal understanding of inverse relations. This study goes beyond lack to explore what children might "have" in their existing conception. A total of 281 students, kindergarten to third grade, were recruited to respond to a questionnaire that involved both contextual and non-contextual tasks on inverse relations, requiring both computational and explanatory skills. Results showed that children demonstrated better performance in computation than explanation. However, many students' explanations indicated that they did not necessarily utilize inverse relations for computation. Rather, they appeared to possess partial understanding, as evidenced by their use of part-whole structure, which is a key to understanding inverse relations. A close inspection of children's solution strategies further revealed that the sophistication of children's conception of part-whole structure varied in representation use and unknown quantity recognition, which suggests rich opportunities to develop students' understanding of inverse relations in lower elementary classrooms.
Eddy current techniques for super duplex stainless steel characterization
International Nuclear Information System (INIS)
Camerini, C.; Sacramento, R.; Areiza, M.C.; Rocha, A.; Santos, R.; Rebello, J.M.; Pereira, G.
2015-01-01
Super duplex stainless steel (SDSS) is a two-phase material where the microstructure consists of grains of ferrite (δ) and austenite (γ). SDSS exhibit an attractive combination of properties, such as: strength, toughness and stress corrosion cracking resistance. Nevertheless, SDSS attain these properties after a controlled solution heat treatment, leading to a similar volumetric fraction of δ and γ. Any further heat treatment, welding operation for example, can change the balance of the original phases, or may also lead to precipitation of a deleterious phase, such as sigma (σ). For these situations, the material corrosion resistance is severely impaired. In the present study, several SDSS samples with low σ phase content and non-balanced microstructure were intentionally obtained by thermally treating SDSS specimens. Electromagnetic techniques, conventional Eddy Current Testing (ECT) and Saturated Low Frequency Eddy Current (SLOFEC), were employed to characterize the SDSS samples. The results showed that ECT and SLOFEC are reliable techniques to evaluate σ phase presence in SDSS and can provide an estimation of the δ content. - Highlights: • Sigma phase precipitation, even for low amounts, dramatically affects SDSS properties. • SDSS samples were thermally treated and carefully characterized by X-Ray Diffraction. • NDT techniques detected low amounts of sigma phase in SDSS microstructure
Eddy current techniques for super duplex stainless steel characterization
Energy Technology Data Exchange (ETDEWEB)
Camerini, C., E-mail: cgcamerini@metalmat.ufrj.br [Laboratory of Non-Destructive Testing, Corrosion and Welding, Department of Metallurgical and Materials Engineering, Federal University of Rio de Janeiro (Brazil); Sacramento, R.; Areiza, M.C.; Rocha, A. [Laboratory of Non-Destructive Testing, Corrosion and Welding, Department of Metallurgical and Materials Engineering, Federal University of Rio de Janeiro (Brazil); Santos, R. [PETROBRAS R& D Center, Rio de Janeiro (Brazil); Rebello, J.M.; Pereira, G. [Laboratory of Non-Destructive Testing, Corrosion and Welding, Department of Metallurgical and Materials Engineering, Federal University of Rio de Janeiro (Brazil)
2015-08-15
Super duplex stainless steel (SDSS) is a two-phase material where the microstructure consists of grains of ferrite (δ) and austenite (γ). SDSS exhibit an attractive combination of properties, such as: strength, toughness and stress corrosion cracking resistance. Nevertheless, SDSS attain these properties after a controlled solution heat treatment, leading to a similar volumetric fraction of δ and γ. Any further heat treatment, welding operation for example, can change the balance of the original phases, or may also lead to precipitation of a deleterious phase, such as sigma (σ). For these situations, the material corrosion resistance is severely impaired. In the present study, several SDSS samples with low σ phase content and non-balanced microstructure were intentionally obtained by thermally treating SDSS specimens. Electromagnetic techniques, conventional Eddy Current Testing (ECT) and Saturated Low Frequency Eddy Current (SLOFEC), were employed to characterize the SDSS samples. The results showed that ECT and SLOFEC are reliable techniques to evaluate σ phase presence in SDSS and can provide an estimation of the δ content. - Highlights: • Sigma phase precipitation, even for low amounts, dramatically affects SDSS properties. • SDSS samples were thermally treated and carefully characterized by X-Ray Diffraction. • NDT techniques detected low amounts of sigma phase in SDSS microstructure.
Vacuum chamber eddy current correction coil for the AGS Booster
International Nuclear Information System (INIS)
Danby, G.; Jackson, J.
1988-01-01
The AGS Booster injector will perform a variety of functions. Heavy ion acceleration requires a bakeable, ultra-high vacuum system (VC). Acceleration for intense proton beams requires rapid cycling (B /preceq/ 10T/sec). If straight forward heavy walled VC are used, the field perturbations due to eddy currents are large. The state of the art lattice has highly distributed lumped sextupoles capable of substantially correcting the induced field nonlinearity. Nevertheless, for the very highest space charge-intensity limits, it is desirable to have the capability to remove eddy current fields at the source. Correction coils attached to the outside of the VC cancel its current aberrations over the required good field aperture. These can be passively powered by transformer action, using two turn windings around the magnet yoke. Programmed power supplies can also be used. This inexpensive additional correction option uses a three turn per quadrant coil which follows the local contour of the VC. Transverse movements of several mms of the VC will have no beam optical effect since the large field aberrations and their corrections have the same displaced coordinates. Experimental and computer studies will be presented, as well as mechanical and electrical design of a simple method of construction. 6 figs
Vacuum chamber eddy current correction coil for the AGS booster
International Nuclear Information System (INIS)
Danby, G.; Jackson, J.
1988-01-01
This paper reports on the AGS Booster injector that performs a variety of functions. Heavy ion acceleration requires a bakeable, ultra-high vacuum system (VC). Acceleration for intense proton beams requires rapid cycling (B ≤10T/sec). If straight forward heavy walled VC are used, the field perturbations due to eddy currents are large. The state of the art lattice has highly distributed lumped sextupoles capable of substantially correcting the induced field nonlinearity. Nevertheless, for the very highest space charge-intensity limits, it is desirable to have the capability to remove eddy current fields at the source. Correction coils attached to the outside of the VC cancel its current aberrations over the required good field aperture. These can be passively powered by transformer action, using two turn windings around the magnet yoke. Programmed power supplies can also be used. This inexpensive additional correction option uses a three turn per quadrant coil which follows the local contour of the VC. Transverse movements of several mms of the VC will have no beam optical effect since the large field aberrations and their corrections have the same displace coordinates. Experimental and computer studies will be presented, as well as mechanical and electrical design of a simple method of construction
Eddy current techniques for super duplex stainless steel characterization
Camerini, C.; Sacramento, R.; Areiza, M. C.; Rocha, A.; Santos, R.; Rebello, J. M.; Pereira, G.
2015-08-01
Super duplex stainless steel (SDSS) is a two-phase material where the microstructure consists of grains of ferrite (δ) and austenite (γ). SDSS exhibit an attractive combination of properties, such as: strength, toughness and stress corrosion cracking resistance. Nevertheless, SDSS attain these properties after a controlled solution heat treatment, leading to a similar volumetric fraction of δ and γ. Any further heat treatment, welding operation for example, can change the balance of the original phases, or may also lead to precipitation of a deleterious phase, such as sigma (σ). For these situations, the material corrosion resistance is severely impaired. In the present study, several SDSS samples with low σ phase content and non-balanced microstructure were intentionally obtained by thermally treating SDSS specimens. Electromagnetic techniques, conventional Eddy Current Testing (ECT) and Saturated Low Frequency Eddy Current (SLOFEC), were employed to characterize the SDSS samples. The results showed that ECT and SLOFEC are reliable techniques to evaluate σ phase presence in SDSS and can provide an estimation of the δ content.
Eddy Current Thermography: System Development and Its Application in NDT
International Nuclear Information System (INIS)
Nurliyana Shamimie Rusli; Ilham Mukriz Zainal Abidin; Sidek, H.A.A.
2015-01-01
Eddy Current Thermography (ECT) is an integrative technique which combines eddy current and thermographic NDT in order to provide an efficient method for defect detection. The technique is applicable to electrically conductive material and has the ability to detect surface and subsurface defect. ECT is a non-contact technique; has the ability to provide instantaneous response and high scanning speed that makes it reliable for defect detection and assessment. The technique combines electromagnetic excitation of the work-piece via a coil carrying current, heating of the material by induction and inspection by transient infrared thermography. In this paper, the development of ECT system is detailed, including coil design for global and local heating of samples, and optimisation of excitation parameters (frequency, power, heating duration etc). Results from 3D FEM simulation and experimental investigations are also presented to provide the overview of underlying phenomena and application of ECT. The work demonstrates the effectiveness of the developed ECT system and technique in defect detection and assessment. (author)
Modeling and analysis of a novel planar eddy current damper
Zhang, He; Kou, Baoquan; Jin, Yinxi; Zhang, Lu; Zhang, Hailin; Li, Liyi
2014-05-01
In this paper, a novel 2-DOF permanent magnet planar eddy current damper is proposed, of which the stator is made of a copper plate and the mover is composed of two orthogonal 1-D permanent magnet arrays with a double sided structure. The main objective of the planar eddy current damper is to provide two orthogonal damping forces for dynamic systems like the 2-DOF high precision positioning system. Firstly, the basic structure and the operating principle of the planar damper are introduced. Secondly, the analytical model of the planar damper is established where the magnetic flux density distribution of the permanent magnet arrays is obtained by using the equivalent magnetic charge method and the image method. Then, the analytical expressions of the damping force and damping coefficient are derived. Lastly, to verify the analytical model, the finite element method (FEM) is adopted for calculating the flux density and a planar damper prototype is manufactured and thoroughly tested. The results from FEM and experiments are in good agreement with the ones from the analytical expressions indicating that the analytical model is reasonable and correct.
Development of eddy current sensor for detecting defect on ferromagnetic material
International Nuclear Information System (INIS)
Choi, Duck Su; Lee, Hyang Beom
2002-01-01
In this paper, the eddy current sensor is developed for observing the ability of detecting defect on ferromagnetic material with variation of frequency and velocity. In order to research the characteristics on eddy current sensor. The circuit which is designed for processing detected voltage is developed and differential frequency is used for eddy current sensor to detect defect with variation of frequency. The ability of eddy current sensor to detect defects is studied with variation of velocity adjusted by rotating the circular plate. This study shows that the ability of eddy current sensor for detecting defect is increased and decreased by frequency. This fact means that the sensor has its best ability at a certain frequency. And the ability of eddy current sensor by velocity is decreased by increased velocity. Therefore, the eddy current sensor has to be developed with consideration of its operation velocity and frequency.
International Nuclear Information System (INIS)
Liu Yueqiang; Albanese, R.; Rubinacci, G.; Portone, A.; Villone, F.
2008-01-01
In order to model a magnetohydrodynamic (MHD) instability that strongly couples to external conducting structures (walls and/or coils) in a fusion device, it is often necessary to combine a MHD code solving for the plasma response, with an eddy current code computing the fields and currents of conductors. We present a rigorous proof of the coupling schemes between these two types of codes. One of the coupling schemes has been introduced and implemented in the CARMA code [R. Albanese, Y. Q. Liu, A. Portone, G. Rubinacci, and F. Villone, IEEE Trans. Magn. 44, 1654 (2008); A. Portone, F. Villone, Y. Q. Liu, R. Albanese, and G. Rubinacci, Plasma Phys. Controlled Fusion 50, 085004 (2008)] that couples the MHD code MARS-F[Y. Q. Liu, A. Bondeson, C. M. Fransson, B. Lennartson, and C. Breitholtz, Phys. Plasmas 7, 3681 (2000)] and the eddy current code CARIDDI[R. Albanese and G. Rubinacci, Adv. Imaging Electron Phys. 102, 1 (1998)]. While the coupling schemes are described for a general toroidal geometry, we give the analytical proof for a cylindrical plasma.
Practical Application of Eddy Currents Generated by Wind
International Nuclear Information System (INIS)
Dirba, I; Kleperis, J
2011-01-01
When a conductive material is subjected to time-varying magnetic fluxes, eddy (Foucault) currents are generated in it and magnetic field of opposite polarity as the applied one arises. Due to the internal resistance of the conductive material, the eddy currents will be dissipated into heat (Joule heating). Conventional domestic water heaters utilize gas burners or electric resistance heating elements to heat the water in the tank and substantial part of the energy to use for it is wasted. In this paper the origin of electromagnetic induction heat generated by wind turbine in special heat exchange camera connected to water boiler is discussed and material evaluation performed using mathematical modelling (comparing the 2D finite element model with analytical and numerical calculation results).
Practical Application of Eddy Currents Generated by Wind
Dirba, I.; Kleperis, J.
2011-06-01
When a conductive material is subjected to time-varying magnetic fluxes, eddy (Foucault) currents are generated in it and magnetic field of opposite polarity as the applied one arises. Due to the internal resistance of the conductive material, the eddy currents will be dissipated into heat (Joule heating). Conventional domestic water heaters utilize gas burners or electric resistance heating elements to heat the water in the tank and substantial part of the energy to use for it is wasted. In this paper the origin of electromagnetic induction heat generated by wind turbine in special heat exchange camera connected to water boiler is discussed and material evaluation performed using mathematical modelling (comparing the 2D finite element model with analytical and numerical calculation results).
Applications of CIVA NDE 10 on Eddy Current Modeling
International Nuclear Information System (INIS)
Nurul Ain Ahmad Latif; Ilham Mukhriz Zainal Abidin; AABdul Razak Hamzah
2011-01-01
CIVA NDE 10 is the simulation software and used as the platform to develop the models dedicated to Eddy Current testing (ET). It has various application in semi analytical modeling approaches. The focus of this paper is to simulate the signals response on the 40 % external groove of the Inconel 600 heat exchanger tubes with outside diameter of 22.22 mm. The inspection were simulated using 17 mm outside diameter differential probe with 100 kHz and 500 kHZ testing frequency. All the simulation results were validated using the experimental results integrated in the CIVA software. The configurations of the probe and tube consisting the flaw show the good agreement between the experimental and the simulated data. (author)
Practical Application of Eddy Currents Generated by Wind
Energy Technology Data Exchange (ETDEWEB)
Dirba, I; Kleperis, J, E-mail: imants.dirba@gmail.com [Institute of Solid State Physics of University of Latvia, 8 Kengaraga Street, Riga, LV-1063 (Latvia)
2011-06-23
When a conductive material is subjected to time-varying magnetic fluxes, eddy (Foucault) currents are generated in it and magnetic field of opposite polarity as the applied one arises. Due to the internal resistance of the conductive material, the eddy currents will be dissipated into heat (Joule heating). Conventional domestic water heaters utilize gas burners or electric resistance heating elements to heat the water in the tank and substantial part of the energy to use for it is wasted. In this paper the origin of electromagnetic induction heat generated by wind turbine in special heat exchange camera connected to water boiler is discussed and material evaluation performed using mathematical modelling (comparing the 2D finite element model with analytical and numerical calculation results).
Eddy current distribution and lift force for finite MAGLEV strips
Energy Technology Data Exchange (ETDEWEB)
Atherton, D L; Eastham, A R; Fombrun, C; Chong, M
1974-07-01
The transverse distribution of induced eddy currents across a flat conducing strip of finite width, due to a rectangular dc magnet moving above it, was modelled experimentally, and was compared with that calculated for an infinite sheet. The electrodynamic suspension was simulated by means of a stationary ac-excited copper magnet suspended above an aluminum strip, and the induced surface current density was measured by a voltage pickup probe connected to a lock-in amplifier. The effect of reducing strip width is examined and shown to produce high current densities close to the edges. These results are related to the variation of lift force with strip width, determined by impedance modelling. A slight enhancement of lift is evident for intermediate strip widths.
Detection of foreign objects using bobbin probe eddy current test
Energy Technology Data Exchange (ETDEWEB)
Jung, Hee Sung; Kweon, Young Ho; Lee, Dong Ha; Shin, Wook Jo; Yim, Chan Ki [ECT Group, Sae-An Engineering Corporation, Seoul (Korea, Republic of)
2016-08-15
Residual foreign objects at the secondary side (top of the tubesheet and tube support plates) of a steam generator are likely to cause a leak by causing wear in the tube. The extent of wear is significantly affected by the material, shape, and size of the foreign object, and the corrosion properties of the tube. The presence of foreign objects at the top of the tubesheet and tube support plates has been identified using remote visual inspection methods such as the foreign object search and retrieval and eddy current test (ECT). The detection of the residual foreign object at the secondary side of a steam generator has limitations that depend on the material properties and the condition of contact with the tube. In this study, which is vertical and horizontal from the upper tubesheet, the corresponding bobbin ECT signals were collected and analyzed to measure its ability to detect foreign objects.
Eddy current inspection of weld defects in tubing
Katragadda, G.; Lord, W.
1992-01-01
An approach using differential probes for the inspection of weld defects in tubing is studied. Finite element analysis is used to model the weld regions and defects. Impedance plane signals are predicted for different weld defect types and compared wherever possible with signals from actual welds in tubing. Results show that detection and sizing of defects in tubing is possible using differential eddy current techniques. The phase angle of the impedance plane trajectory gives a good indication of the sizing of the crack. Data on the type of defect can be obtained from the shape of the impedance plane trajectory and the phase. Depending on the skin depth, detection of outer wall, inner wall, and subsurface defects is possible.
Computer programs for eddy-current defect studies
International Nuclear Information System (INIS)
Pate, J.R.; Dodd, C.V.
1990-06-01
Several computer programs to aid in the design of eddy-current tests and probes have been written. The programs, written in Fortran, deal in various ways with the response to defects exhibited by four types of probes: the pancake probe, the reflection probe, the circumferential boreside probe, and the circumferential encircling probe. Programs are included which calculate the impedance or voltage change in a coil due to a defect, which calculate and plot the defect sensitivity factor of a coil, and which invert calculated or experimental readings to obtain the size of a defect. The theory upon which the programs are based is the Burrows point defect theory, and thus the calculations of the programs will be more accurate for small defects. 6 refs., 21 figs
Computer programs for eddy-current defect studies
Energy Technology Data Exchange (ETDEWEB)
Pate, J. R.; Dodd, C. V. [Oak Ridge National Lab., TN (USA)
1990-06-01
Several computer programs to aid in the design of eddy-current tests and probes have been written. The programs, written in Fortran, deal in various ways with the response to defects exhibited by four types of probes: the pancake probe, the reflection probe, the circumferential boreside probe, and the circumferential encircling probe. Programs are included which calculate the impedance or voltage change in a coil due to a defect, which calculate and plot the defect sensitivity factor of a coil, and which invert calculated or experimental readings to obtain the size of a defect. The theory upon which the programs are based is the Burrows point defect theory, and thus the calculations of the programs will be more accurate for small defects. 6 refs., 21 figs.
Reliability of eddy current examination of steam generator tubes
International Nuclear Information System (INIS)
Birks, A.S.; Ferris, R.H.; Doctor, P.G.; Clark, R.A.; Spanner, G.E.
1985-04-01
A unique study of nondestructive examination reliability is underway at the Pacific Northwest Laboratory under US Nuclear Regulatory Commission sponsorship. Project participants include the Electric Power Research Institute and consortiums from France, Italy, and Japan. This study group has conducted a series of NDE examinations of tubes from a retired-from-service steam generator, using commercially available multifrequency eddy current equipment and ASME procedures. The examination results have been analyzed to identify factors contributing to variations in NDE inspection findings. The reliability of these examinations will then be validated by destructive analyses of the steam generator tubes. The program is expected to contribute to development of a model for steam generator inservice inspection sampling plans and inspection periods, as well as to improved regulatory guidelines for tube plugging
Theoretical and practical program in the non-destructive testing by eddy currents - the first level
International Nuclear Information System (INIS)
Shaaban, H.I.; Addarwish, J.M.A.
2014-11-01
The testing using eddy currents is one of the non-destructive tests that use electromagnetic property as a basis for testing procedures, and there are many other ways to use this principle, including Remote Field Testing and the Magnetic Flux Leakage test. Eddy currents are electrical currents moving in a circular path, and took the name eddy of eddies that form when a liquid or gas is moving in a circular path because of objection obstacles to its track. They are generated in the material using a variable magnetic field. Non-destructive testing by eddy currents is a technique used for the detection of defects and interruptions in a material and it is a process that relies on the generation of small eddy currents in the material of the part to be examined, provided that this part is of an electrically conducting material. This technique and its scientific basis are explained in this book. Also the devices used in this technique and how to use these devices in details are explained. The book contains Twelve chapters: Introduction to non destructive testing - Engineering materials and its mechanical characteristics - Electrical and magnetic characteristics of engineering materials - Introduction to testing by eddy currents - Factors affecting eddy currents - Basis of electrical circuits used in eddy currents testing devices - Probes of eddy currents testing - Eddy currents testing devices (Theoretical) - Analysis of the examination results of testing by eddy currents: techniques and applications - Applications of testing by eddy currents - Eddy currents testing devices (Application) - Practical lessons for the first level in testing by eddy currents.
Unfolding in particle physics: A window on solving inverse problems
International Nuclear Information System (INIS)
Spano, F.
2013-01-01
Unfolding is the ensemble of techniques aimed at resolving inverse, ill-posed problems. A pedagogical introduction to the origin and main problems related to unfolding is presented and used as the the stepping stone towards the illustration of some of the most common techniques that are currently used in particle physics experiments. (authors)
Solving probabilistic inverse problems rapidly with prior samples
Käufl, Paul; Valentine, Andrew P.; de Wit, Ralph W.; Trampert, Jeannot
2016-01-01
Owing to the increasing availability of computational resources, in recent years the probabilistic solution of non-linear, geophysical inverse problems by means of sampling methods has become increasingly feasible. Nevertheless, we still face situations in which a Monte Carlo approach is not
Validation of a Residual Stress Measurement Method by Swept High-Frequency Eddy Currents
International Nuclear Information System (INIS)
Lee, C.; Shen, Y.; Lo, C. C. H.; Nakagawa, N.
2007-01-01
This paper reports on a swept high-frequency eddy current (SHFEC) measurement method developed for electromagnetic nondestructive characterization of residual stresses in shot peened aerospace materials. In this approach, we regard shot-peened surfaces as modified surface layers of varying conductivity, and determine the conductivity deviation profile by inversion of the SHFEC data. The SHFEC measurement system consists of a pair of closely matched printed-circuit-board coils driven by laboratory instrument under software control. This provides improved sensitivity and high frequency performance compared to conventional coils, so that swept frequency EC measurements up to 50 MHz can be made to achieve the smallest skin depth of 80 μm for nickel-based superalloys. We devised a conductivity profile inversion procedure based on the laterally uniform multi-layer theory of Cheng, Dodd and Deeds. The main contribution of this paper is the methodology validation. Namely, the forward and inverse models were validated against measurements on artificial layer specimens consisting of metal films with different conductivities placed on a metallic substrate. The inversion determined the film conductivities which were found to agree with those measured using the direct current potential drop (DCPD) method
Validation of a Residual Stress Measurement Method by Swept High-Frequency Eddy Currents
Lee, C.; Shen, Y.; Lo, C. C. H.; Nakagawa, N.
2007-03-01
This paper reports on a swept high-frequency eddy current (SHFEC) measurement method developed for electromagnetic nondestructive characterization of residual stresses in shot peened aerospace materials. In this approach, we regard shot-peened surfaces as modified surface layers of varying conductivity, and determine the conductivity deviation profile by inversion of the SHFEC data. The SHFEC measurement system consists of a pair of closely matched printed-circuit-board coils driven by laboratory instrument under software control. This provides improved sensitivity and high frequency performance compared to conventional coils, so that swept frequency EC measurements up to 50 MHz can be made to achieve the smallest skin depth of 80 μm for nickel-based superalloys. We devised a conductivity profile inversion procedure based on the laterally uniform multi-layer theory of Cheng, Dodd and Deeds. The main contribution of this paper is the methodology validation. Namely, the forward and inverse models were validated against measurements on artificial layer specimens consisting of metal films with different conductivities placed on a metallic substrate. The inversion determined the film conductivities which were found to agree with those measured using the direct current potential drop (DCPD) method.
Particular treatments in Eddy current technique. Application to the control of corrugated tubes
International Nuclear Information System (INIS)
1982-11-01
When the testing of a given product shows that, owing to a particular shape of this product or to its environment, disturbing effects can hide the presence of harmful defects, use must be made of testing artifices or particular treatments enabling an efficient examination to be made. On this score, many eddy current problems are solved by means of the following processes: - use of specific sensors adapted to the geometry of the product, - spectral analysis of the analog results of analyses, - combination of the results of analyses obtained simultaneously at different frequencies (multifrequency techniques). An example of an application is given for corrugated tubes achieved by hollow and helical milling of smooth tubes [fr
Desmal, Abdulla; Bagci, Hakan
2014-01-01
A numerical framework that incorporates recently developed iterative shrinkage thresholding (IST) algorithms within the Born iterative method (BIM) is proposed for solving the two-dimensional inverse electromagnetic scattering problem. IST
Solving inverse problems for biological models using the collage method for differential equations.
Capasso, V; Kunze, H E; La Torre, D; Vrscay, E R
2013-07-01
In the first part of this paper we show how inverse problems for differential equations can be solved using the so-called collage method. Inverse problems can be solved by minimizing the collage distance in an appropriate metric space. We then provide several numerical examples in mathematical biology. We consider applications of this approach to the following areas: population dynamics, mRNA and protein concentration, bacteria and amoeba cells interaction, tumor growth.
Current state and development trends of inspections of steam generator tubes by eddy currents method
International Nuclear Information System (INIS)
Kubis, S.; Herman, M.
1988-01-01
The requirements are presented for steam generator tube testing and the factors are discussed affecting the accuracy of measurement by the eddy currents method. The individual types of the eddy currents method are described, such as the single-frequency method, the multi-frequency method and the pulse eddy currents method. The demands are summed up on manipulator systems whose design is adapted to the steam generator configuration conditions. (E.S.). 5 figs., 16 possu
Coupling between eddy currents and rigid body rotation: analysis, computation, and experiments
International Nuclear Information System (INIS)
Hua, T.Q.; Turner, L.R.
1985-01-01
Computation and experiment show that the coupling between eddy currents and the angular deflections resulting from those eddy currents can reduce electromagnetic effects such as forces, torques, and power dissipation to levels far less severe than would be predicted without regard for the coupling. This paper explores the coupling effects beyond the parameter range that has been explored experimentally, using analytical means and the eddy-current computer code EDDYNET. The paper also describes upcoming FELIX experiments with cantilevered beams
3-D analysis of eddy current in permanent magnet of interior permanent magnet motors
International Nuclear Information System (INIS)
Kawase, Yoshihiro; Yamaguchi, Tadashi; Fukanaga, Hiromu; Ito, Shokichi
2002-01-01
Interior permanent magnet motors are widely used in various fields. However, in high-speed operations, it is important to decrease the eddy current loss in the permanent magnet. In order to decrease the eddy current loss, we propose to divide the permanent magnet. In this paper, we clarified the effect of division of permanent magnet on the eddy current loss using the 3-D finite element method. (Author)
Solving Inverse Kinematics – A New Approach to the Extended Jacobian Technique
Directory of Open Access Journals (Sweden)
M. Šoch
2005-01-01
Full Text Available This paper presents a brief summary of current numerical algorithms for solving the Inverse Kinematics problem. Then a new approach based on the Extended Jacobian technique is compared with the current Jacobian Inversion method. The presented method is intended for use in the field of computer graphics for animation of articulated structures.
International Nuclear Information System (INIS)
Itagaki, Masafumi; Sanpei, Akio; Masamune, Sadao; Watanabe, Kiyomasa
2014-01-01
For the MHD equilibrium reconstruction of a reverse field pinch device, it is a big issue to identify accurately the strong eddy current flow on the shell. In the present work, boundary integrals of the eddy current along the shell are added to the conventional Cauchy-condition surface method formulation. The eddy current profile is unknown in advance but straightforwardly identified using only the signals from magnetic sensors located outside the plasma. Two ideas are introduced to overcome the numerical difficulties encountered in the problem. One is an accurate boundary integral scheme to damp out the near singularity occurring at the sensor position very close to the shell. The other is the modified truncated singular value decomposition technique to solve an ill-conditioned matrix equation when a large number of nodal points exist on the shell. The capability of the new method is demonstrated for a test problem modeling the RELAX device. (author)
Detection of localized damage by eddy currents technique
Directory of Open Access Journals (Sweden)
Aoukili A.
2014-01-01
Full Text Available Non destructive evaluation techniques based on eddy currents (EC are largely used for quality control of the castings in a lot of industries. The principle of detection by EC consists in using an adequate inductive coil to generate them by a variable magnetic field, and measuring their effects by using one or several sensors. These effects result from the interaction between the induced magnetic field and the excited conductive material. A local variation of the physical properties or geometry of the tested sample, due to a singularity or a flaw, causes a modification of the EC distribution, enabling thus detection. In order to optimize the capacity of defect revealing by means of EC based probes, an accurate modelling of the problem is essential. This can be used to perform simulation of the EC distribution under different circumstances and to analyze the EC sensitivity to the various implicated parameters. In this work, the modelling of EC is made by using the finite element method. Using a B-scan strategy was used, detection of a small defect having the shape of an open cavity is shown to be correctly indicated via monitoring variations of the induced voltage in the receiver coil.
Preliminary Investigations of Eddy Current Effects on a Spinning Disk
International Nuclear Information System (INIS)
Piggott, W T; Walston, S; Mayhall, D
2006-01-01
The design of the positron source target for the International Linear Collider (ILC) envisions a Ti6Al4V wheel rotating in a large magnetic field (5-10 Tesla) being impacted by a photon beam to produce positrons. One of the many challenges for this system is determining how large a motor will be needed to spin the shaft. The wheel spinning in the magnetic field induces an eddy current in the wheel, which retards the spinning motion of the wheel. Earlier calculations by Mayhall [1] have shown that those eddy forces could be quite large, and resulted in the preliminary design being moved from a solid disk to a rim and spoke design, as shown in Figure 1. A series of experiments with a spinning metal disk were run at the Stanford Linear Accelerator Center (SLAC) to provide experimental validation of the Maxwell 3D simulations. This report will give a brief outline of the experimental setup and results. In addition, earlier work by Smythe [2] will be used to compare with the experimental results
New eddy current testing system in steam generator tubes
International Nuclear Information System (INIS)
Nagata, Yasuyuki; Shimone, Junri; Maeda, Kotaro; Harada, Yutaka; Murakami, Ryuji
2003-01-01
Eddy Current Testing (ECT) technique is applied to PWR Steam Generator (SG) tubes during refueling outage inspection. Bobbin type probe is generally used for the inspection, but it cannot provide sufficient detectability for very tight cracks. NEL, R/D Tech (Canada) and AECL (Canada) jointly developed new ECT probe. The probe is transmit and receive type array probe. It has axial defect detection mode and circumferential defect detection mode. Its inspection speed is as fast as conventional bobbin probe, and detectability performance is same or better than performance of rotating pancake coil (RPC) probe, which is used for detailed inspection. As a tester of the new probe, we have developed new ECT tester TC7700. It is able to transmit composite wave from the 4 independent oscillators (simultaneous excitation system) compared with the conventional inspection system. As regarding for field inspection system, we have integrated Zetec (USA) probe positioner, probe pusher and R/D Tech TC7700. We are also developing new analysis software. The software has automated data screening function, which can deal with large amount of data compared with conventional bobbin probe. We plan to perform a large-scale field trial using the probe and new system in near future. (author)
Experimental modeling of eddy currents and deflections for tokamak limiters
International Nuclear Information System (INIS)
Hua, T.Q.; Knott, M.J.; Turner, L.R.; Wehrle, R.B.
1986-01-01
In this study, experiments were performed to investigate deflection, current, and material stress in cantilever beams with the Fusion ELectromagnetic Induction eXperiment (FELIX) at the Argonne National Laboratory. Since structures near the plasma are typically cantilevered, the beams provide a good model for the limiter blades of a tokamak fusion reactor. The test pieces were copper, aluminum, phosphor bronze, and brass cantilever beams, clamped rigidly at one end with a nonconducting support frame inside the FELIX test volume. The primary data recorded as functions of time were the beam deflection measured with a noncontact electro-optical device, the total eddy current measured with a Rogowski coil and linking through a central hole in the beam, and the material stress extracted from strain gauges. Measurements of stress and deflection were taken at selected positions along the beam. The extent of the coupling effect depends on several factors. These include the size, the electrical and mechanical properties of the beam, segmenting of the beam, the decay rate of the dipole field, and the strength of the solenoid field
Variable current speed controller for eddy current motors
Gerth, H.L.; Bailey, J.M.; Casstevens, J.M.; Dixon, J.H.; Griffith, B.O.; Igou, R.E.
1982-03-12
A speed control system for eddy current motors is provided in which the current to the motor from a constant frequency power source is varied by comparing the actual motor speed signal with a setpoint speed signal to control the motor speed according to the selected setpoint speed. A three-phase variable voltage autotransformer is provided for controlling the voltage from a three-phase power supply. A corresponding plurality of current control resistors is provided in series with each phase of the autotransformer output connected to inputs of a three-phase motor. Each resistor is connected in parallel with a set of normally closed contacts of plurality of relays which are operated by control logic. A logic circuit compares the selected speed with the actual motor speed obtained from a digital tachometer monitoring the motor spindle speed and operated the relays to add or substract resistance equally in each phase of the motor input to vary the motor current to control the motor at the selected speed.
Quantitative Evaluation of Remote Field Eddy Current Defect Signals
International Nuclear Information System (INIS)
Jeong, Jin Oh; Yi, Jae Kyung; Kim, Hyoung Jean
2000-01-01
The remote field eddy current (RFEC) inspection was performed on the ductile cast iron pipes with nominal outer diameter of 100mm, which were machined with various shapes and sizes of defects. Ductile cast iron pipes which are used as water supply pipe have the non-uniform thickness and asymmetric cross section due to relatively high degree of allowable errors during the manufacturing processes. These characteristics of ductile cast in pipes cause the long range background noises in RFEC signals along the pipe. In this study, tile machined defects in pipes were effectively classified by the moving window average (MWA) method which eliminated the long-range noise. The voltage plane polar plots (VPPP) method was used to quantitatively evaluate the depth and circumferential degree of defects. The VPPP signatures showed that the angle between defect signature and the normalized in-phase component on the VPPP is linear to the depth of defects. The nondestructive RFEC technique proved to be capable of quantitatively evaluating the machined defects of underground water supply pipe
Eddy current septum magnets for injection and extraction at SSRF
International Nuclear Information System (INIS)
Ouyang Lianhua; Gu Ming; Liu Bo; Chen Rong
2010-01-01
There are 6 in-vacuum eddy current septum magnets used for booster injection, extraction, and storage ring injection in SSRF. Special attention was paid to coils and their support designs because of the shock force they bear in the magnetic fields and the high heat which is hard to be dissipated in vacuum environment. For the storage ring magnets, good transverse homogeneity in the gap was achieved by careful design, precise machining and accurate assembly; and an extremely low leakage field on the stored beam is another key feature thanks to the high permeability Mu metal. Magnetic field measurement was conducted with both a point coil and a long integral coil, and the results agree well with the OPERA-2d/3d simulations. An inner tube is added to keep the continuity of impedance for the circulating beam with two RF finger flanges at each end. There is no vacuum separation between the inner tube and the magnet chamber. Sputter ion pumps integrated with NEG are used to acquire the UHV for the chamber. (authors)
Amplitude-independent flaw length determination using differential eddy current
Shell, E.
2013-01-01
Military engine component manufacturers typically specify the eddy current (EC) inspection requirements as a crack length or depth with the assumption that the cracks in both the test specimens and inspected component are of a similar fixed aspect ratio. However, differential EC response amplitude is dependent on the area of the crack face, not the length or depth. Additionally, due to complex stresses, in-service cracks do not always grow in the assumed manner. It would be advantageous to use more of the information contained in the EC data to better determine the full profile of cracks independent of the fixed aspect ratio amplitude response curve. A specimen with narrow width notches is used to mimic cracks of varying aspect ratios in a controllable manner. The specimen notches have aspect ratios that vary from 1:1 to 10:1. Analysis routines have been developed using the shape of the EC response signals that can determine the length of a surface flaw of common orientations without use of the amplitude of the signal or any supporting traditional probability of detection basis. Combined with the relationship between signal amplitude and area, the depth of the flaw can also be calculated.
Study on classical and excess eddy currents losses of Terfenol-D
Energy Technology Data Exchange (ETDEWEB)
Talebian, Soheil; Hojjat, Yousef [Department of Mechanical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Ghodsi, Mojtaba [Department of Mechanical and Industrial Engineering, Sultan Qaboos University, Muscat (Oman); Karafi, Mohammad Reza [Department of Mechanical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)
2015-08-15
In the present paper, classical and excess eddy currents losses of Terfenol-D are studied and effects of magnetic field frequency, peak of magnetic flux density and diameter of Terfenol-D on the eddy currents losses are investigated. To provide reliable data for the purpose of the paper, an experimental laboratory is fabricated and used to obtain major and minor hysteresis loops of Terfenol-D at different frequencies. In theoretical study, initially an analytical model based on uniform distribution of magnetic flux is developed which yields to calculation of classical eddy currents losses. Then, another eddy currents model based on non-uniform distribution of magnetic flux and nonlinear diffusion of electromagnetic fields is presented. The difference between output values of the two models is identified as excess eddy currents losses. Obtained results show that the values of excess losses are generally larger than classical losses and applying just classical model leads to wrong calculation of actual value of eddy currents losses. For the results obtained from two above models, empirical models with respect to the magnetic field frequency and the peak value of magnetic flux density are achieved which can predict the eddy currents losses precisely. To validate the empirical relations, experiments are repeated at a new frequency and values of power losses calculated from analytical equations are compared with the predicted values of the empirical models. The results point towards possibility to use the obtained empirical relations in order to calculate the classical and excess eddy currents losses of Terfenol-D at the frequencies below 200 Hz and different values of magnetic flux density. - Highlights: • Classical eddy currents loss of Terfenol-D is studied using Maxwell's laws. • Excess eddy currents loss of Terfenol-D is studied using Mayergoyz nonlinear model. • Effects of Terfenol-D geometry on the eddy currents losses are investigated. • Power
Three-dimensional eddy current solution of a polyphase machine test model (abstract)
Pahner, Uwe; Belmans, Ronnie; Ostovic, Vlado
1994-05-01
This abstract describes a three-dimensional (3D) finite element solution of a test model that has been reported in the literature. The model is a basis for calculating the current redistribution effects in the end windings of turbogenerators. The aim of the study is to see whether the analytical results of the test model can be found using a general purpose finite element package, thus indicating that the finite element model is accurate enough to treat real end winding problems. The real end winding problems cannot be solved analytically, as the geometry is far too complicated. The model consists of a polyphase coil set, containing 44 individual coils. This set generates a two pole mmf distribution on a cylindrical surface. The rotating field causes eddy currents to flow in the inner massive and conducting rotor. In the analytical solution a perfect sinusoidal mmf distribution is put forward. The finite element model contains 85824 tetrahedra and 16451 nodes. A complex single scalar potential representation is used in the nonconducting parts. The computation time required was 3 h and 42 min. The flux plots show that the field distribution is acceptable. Furthermore, the induced currents are calculated and compared with the values found from the analytical solution. The distribution of the eddy currents is very close to the distribution of the analytical solution. The most important results are the losses, both local and global. The value of the overall losses is less than 2% away from those of the analytical solution. Also the local distribution of the losses is at any given point less than 7% away from the analytical solution. The deviations of the results are acceptable and are partially due to the fact that the sinusoidal mmf distribution was not modeled perfectly in the finite element method.
Ahmed, Shamim; Miorelli, Roberto; Calmon, Pierre; Anselmi, Nicola; Salucci, Marco
2018-04-01
This paper describes Learning-By-Examples (LBE) technique for performing quasi real time flaw localization and characterization within a conductive tube based on Eddy Current Testing (ECT) signals. Within the framework of LBE, the combination of full-factorial (i.e., GRID) sampling and Partial Least Squares (PLS) feature extraction (i.e., GRID-PLS) techniques are applied for generating a suitable training set in offine phase. Support Vector Regression (SVR) is utilized for model development and inversion during offine and online phases, respectively. The performance and robustness of the proposed GIRD-PLS/SVR strategy on noisy test set is evaluated and compared with standard GRID/SVR approach.
Solving Inverse Detection Problems Using Passive Radiation Signatures
International Nuclear Information System (INIS)
Favorite, Jeffrey A.; Armstrong, Jerawan C.; Vaquer, Pablo A.
2012-01-01
The ability to reconstruct an unknown radioactive object based on its passive gamma-ray and neutron signatures is very important in homeland security applications. Often in the analysis of unknown radioactive objects, for simplicity or speed or because there is no other information, they are modeled as spherically symmetric regardless of their actual geometry. In these presentation we discuss the accuracy and implications of this approximation for decay gamma rays and for neutron-induced gamma rays. We discuss an extension of spherical raytracing (for uncollided fluxes) that allows it to be used when the exterior shielding is flat or cylindrical. We revisit some early results in boundary perturbation theory, showing that the Roussopolos estimate is the correct one to use when the quantity of interest is the flux or leakage on the boundary. We apply boundary perturbation theory to problems in which spherically symmetric systems are perturbed in asymmetric nonspherical ways. We apply mesh adaptive direct search (MADS) algorithms to object reconstructions. We present a benchmark test set that may be used to quantitatively evaluate inverse detection methods.
Eddy current heating of irregularly shaped plates by slow ramped fields
International Nuclear Information System (INIS)
Dresner, L.
1979-01-01
Theorems are presented for estimating eddy current heating of irregularly shaped plates by a perpendicular ramped field. The theorems, which are derived from two complementary variational principles, give upper and lower bounds to the eddy current heating. Illustrative results are given for rectangles, isosceles triangles, sectors of circular annuli, rhombuses, and L-shaped plates. A comparison is made with earlier work
Directory of Open Access Journals (Sweden)
Damhuji Rifai
2016-02-01
Full Text Available Non-destructive eddy current testing (ECT is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper.
Eddy current testing. Evaluation of cracks propagation in austenitic steel cladding
International Nuclear Information System (INIS)
Pigeon, M.
1983-12-01
A low frequency eddy current method has been developed to evaluate the ligament between crack front and cladding surface and measure crack length. It uses a large surface probe to obtain a low sensitivity on surface variations and a good penetration of eddy current
Numerical and experimental analysis of eddy currents induced in tokamak machines
International Nuclear Information System (INIS)
Takahashi, T.; Takahashi, G.; Kazawa, Y.; Suzuki, Y.
1977-01-01
This paper deals with eddy current phenomena in Tokamak machines. A numerical method is presented which will permit eddy currents to be calculated. Examples of numerical results and a discussion of the JT-60 are shown. Calculations are checked by measurements in basic models
Rifai, Damhuji; Abdalla, Ahmed N.; Ali, Kharudin; Razali, Ramdan
2016-01-01
Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper. PMID:26927123
International Nuclear Information System (INIS)
Stenvall, A; Tarhasaari, T
2010-01-01
Many people these days employ only commercial finite element method (FEM) software when solving for the hysteresis losses of superconductors. Thus, the knowledge of a modeller is in the capability of using the black boxes of software efficiently. This has led to a relatively superficial examination of different formulations while the discussion stays mainly on the usage of the user interfaces of these programs. Also, if we stay only at the mercy of commercial software producers, we end up having less and less knowledge on the details of solvers. Then, it becomes more and more difficult to conceptually solve new kinds of problem. This may prevent us finding new kinds of method to solve old problems more efficiently, or finding a solution for a problem that was considered almost impossible earlier. In our earlier research, we presented the background of a co-tree gauged T-ψ FEM solver for computing the hysteresis losses of superconductors. In this paper, we examine the feasibility of FEM and eddy current vector potential formulation in the same problem.
Automation of eddy current system for in-service inspection of turbine and generator rotor bores
International Nuclear Information System (INIS)
Anon.
1987-01-01
The current project (EPRI-RP-1975-5) is a continuation of activities that began several years ago. Those results (EPRI-RP-1957-1) indicated that eddy current testing shows promise for in-service inspection. The current project investigates the degree to which eddy current testing can be used to replace bore magnetic particle testing. For this purpose, correlation studies between eddy current and magnetic particle tests are being undertaken on laboratory rotor sections and field test pieces of rotors. The eddy current data are to be gathered automatically by a combination of the Nortec-25L Eddyscope (to provide the analog eddy current signals) and the General Electric DATAQ/sup TM/ (a registered trademark of the General Electric Co.) System (to perform the automatic data acquisition). This paper describes some test results on a flaked laboratory rotor section
Solving inverse two-point boundary value problems using collage coding
Kunze, H.; Murdock, S.
2006-08-01
The method of collage coding, with its roots in fractal imaging, is the central tool in a recently established rigorous framework for solving inverse initial value problems for ordinary differential equations (Kunze and Vrscay 1999 Inverse Problems 15 745-70). We extend these ideas to solve the following inverse problem: given a function u(x) on [A, B] (which may be the interpolation of data points), determine a two-point boundary value problem on [A, B] which admits u(x) as a solution as closely as desired. The solution of such inverse problems may be useful in parameter estimation or determination of potential functional forms of the underlying differential equation. We discuss ways to improve results, including the development of a partitioning scheme. Several examples are considered.
Rifai, Damhuji; Abdalla, Ahmed N.; Razali, Ramdan; Ali, Kharudin; Faraj, Moneer A.
2017-01-01
The use of the eddy current technique (ECT) for the non-destructive testing of conducting materials has become increasingly important in the past few years. The use of the non-destructive ECT plays a key role in the ensuring the safety and integrity of the large industrial structures such as oil and gas pipelines. This paper introduce a novel ECT probe design integrated with the distributed ECT inspection system (DSECT) use for crack inspection on inner ferromagnetic pipes. The system consists of an array of giant magneto-resistive (GMR) sensors, a pneumatic system, a rotating magnetic field excitation source and a host PC acting as the data analysis center. Probe design parameters, namely probe diameter, an excitation coil and the number of GMR sensors in the array sensor is optimized using numerical optimization based on the desirability approach. The main benefits of DSECT can be seen in terms of its modularity and flexibility for the use of different types of magnetic transducers/sensors, and signals of a different nature with either digital or analog outputs, making it suited for the ECT probe design using an array of GMR magnetic sensors. A real-time application of the DSECT distributed system for ECT inspection can be exploited for the inspection of 70 mm carbon steel pipe. In order to predict the axial and circumference defect detection, a mathematical model is developed based on the technique known as response surface methodology (RSM). The inspection results of a carbon steel pipe sample with artificial defects indicate that the system design is highly efficient. PMID:28335399
Seo, Sukho; Choi, Gyudong; Eom, Tae Jhoun; Lee, Bokwon; Lee, Soo Yeol
2017-07-01
The eddy current responses of Electrical Discharge Machining (EDM) notches and fatigue cracks are directly compared to verify the reliability of eddy current inspection. The fatigue crack growth tests using a constant load range control mode were conducted to obtain a variety of edge crack sizes, ranging from 0.9 to 6.6 mm for Al alloy and from 0.1 to 3 mm for Ti alloy. EDM notch specimens of Al and Ti alloys were accordingly prepared in lengths similar to that of the fatigued specimen. The crack length was determined by optical microscope and scanning electron microscope. The eddy current responses between the EDM and fatigued specimens with varying notch/crack length were examined using probe sensors at (100-500) kHz and (1-2) MHz for Al and Ti alloys, respectively. The results show a significant difference in the eddy current signal between the two specimens, based on the correlation between the eddy current response and notch/crack length. This suggests that eddy current inspection using the EDM reference specimen is inaccurate in determining the precise crack size, unless the eddy current response data base is obtained from a fatigue-cracked specimen.
Eddy current and ultrasonic fuel channel inspection at Karachi Nuclear Power Plant
International Nuclear Information System (INIS)
Mayo, W.R.; Alam, M.M.
1997-01-01
In November of 1993 and in-service inspection was performed on eight fuel channels in the Karachi Nuclear Power Plant (KANUPP) reactor. The workscope included ultrasonic and eddy current volumetric examinations, and eddy current measurement of pressure-to calandria tube gap. This paper briefly discusses the planning strategy of the ultrasonic and eddy current examinations, and describes the equipment developed to meet the requirements, followed by details of the actual channel inspection campaign. The presented nondestructive examinations assisted in determining fitness for service of KANUPP reactor channels in general, and confirmed that the problems associated with channel G12 were not generic in nature. (author)
Krauter, N.; Stefani, F.
2017-10-01
Eddy current flow meters are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system that is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation.
Perturbation-polynomial expansion formulation of 3-D eddy current problems
International Nuclear Information System (INIS)
Yeh, H.T.
1977-01-01
A pulsed magnetic field is required in Tokamak fusion machines. Eddy currents produced by the pulsed field may produce undesirable effects, e.g., in the mechanical loading of the vacuum vessel, heating in the magnet and structure, and field ripple in the plasma region. A method has been developed earlier to calculate the eddy current produced in a thin object by the linear ramping of a magnetic dipole. We report here extension of the method to calculate the eddy current induced in three-dimensional objects and by pulse coils of general shape. Examples are given
Three-dimensional analysis of eddy current with the finite element method
International Nuclear Information System (INIS)
Takano, Ichiro; Suzuki, Yasuo
1977-05-01
The finite element method is applied to three-dimensional analysis of eddy current induced in a large Tokamak device (JT-60). Two techniques to study the eddy current are presented: those of ordinary vector potential and modified vector potential. The latter is originally developed for decreasing dimension of the global matrix. Theoretical treatment of these two is given. The skin effect for alternate current flowing in the circular loop of rectangular cross section is examined as an example of the modified vector potential technique, and the result is compared with analytical one. This technique is useful in analysis of the eddy current problem. (auth.)
Analysis of eddy current losses during discharging period in a 600 kJ SMES
International Nuclear Information System (INIS)
Park, M.J.; Kwak, S.Y.; Lee, S.Y.; Kim, W.S.; Lee, J.K.; Park, C.; Choi, K.; Bae, J.H.; Kim, S.H.; Sim, K.D.; Seong, K.C.; Jung, H.K.; Hahn, S.
2008-01-01
The operation of the SMES system can be divided into three modes such as charging, operating and discharging. During the charging and the discharging modes, a magnetic field variation due to the current increase and decrease generate eddy current losses in the SMES system. The eddy current loss in discharging mode is the major factor to be considered because the operating time in the mode is fixed, whereas the charging mode has the arbitrary operating time which is not fixed. In this paper, we present the analysis results of the eddy current losses which are generated in the 600 kJ class HTS SMES system during the discharging mode
International Nuclear Information System (INIS)
Krauter, N; Stefani, F
2017-01-01
Eddy current flow meters are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system that is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation. (paper)
Application of wavelet analysis to signal processing methods for eddy-current test
International Nuclear Information System (INIS)
Chen, G.; Yoneyama, H.; Yamaguchi, A.; Uesugi, N.
1998-01-01
This study deals with the application of wavelet analysis to detection and characterization of defects from eddy-current and ultrasonic testing signals of a low signal-to-noise ratio. Presented in this paper are the methods for processing eddy-current testing signals of heat exchanger tubes of a steam generator in a nuclear power plant. The results of processing eddy-current testing signals of tube testpieces with artificial flaws show that the flaw signals corrupted by noise and/or non-defect signals can be effectively detected and characterized by using the wavelet methods. (author)
Yamazaki, Katsumi; Kanou, Yuji; Fukushima, Yu; Ohki, Shunji; Nezu, Akira; Ikemi, Takeshi; Mizokami, Ryoichi
In this paper, we present the development of interior magnet motors with concentrated windings, which reduce the eddy current loss of the magnets. First, the mechanism of the magnet eddy current loss generation is investigated by a simple linear magnetic circuit. Due to the consideration, an automatic optimization method using an adaptive finite element method is carried out to determine the stator and rotor shapes, which decrease the eddy current loss of the magnet. The determined stator and rotor are manufactured in order to proof the effectiveness by the measurement.
Eddy current loss calculation and thermal analysis of axial-flux permanent magnet couplers
Directory of Open Access Journals (Sweden)
Di Zheng
2017-02-01
Full Text Available A three-dimensional magnetic field analytical model of axial-flux permanent magnet couplers is presented to calculate the eddy current loss, and the prediction of the copper plate temperature under various loads is analyzed. The magnetic field distribution is calculated, and then the eddy current loss is obtained, with the magnetic field analytical model established in cylindrical coordinate. The influence of various loads on eddy current loss is analyzed. Furthermore, a thermal model of axial-flux permanent magnet couplers is established by taking the eddy current loss as the heat source, using the electromagnetic-thermal coupled method. With the help of the thermal model, the influence of various loads on copper plate temperature rise is also analyzed. The calculated results are compared with the results of finite element method and measurement. The comparison results confirm the validity of the magnetic field analytical model and thermal model.
A Review of Material Properties Estimation Using Eddy Current Testing and Capacitor Imaging
Directory of Open Access Journals (Sweden)
Mohd. Amri Yunus
2009-01-01
Full Text Available he non destructive testing applications based on inductive (eddy current testing and capacitive sensors are widely used for imaging of material properties. The simple structure, safe to use, low cost, non contact application, good response at medium range frequency of the sensors make them preferable to be used in the industries. The aim of this study is to talk about the material properties estimation applications using eddy current testing and capacitive sensing. The basic operations of eddy current testing and capacitive sensing with example of application in the non destructive testing are discussed. Next, the recent advancements of eddy current testing and capacitive testing in imaging technique are presented in this paper.
An application of the eddy-current method for inspections of austenitic cladding
International Nuclear Information System (INIS)
Kubis, S.; Herka, M.; Krajcovic, R.
1999-01-01
The application of the eddy-current method for inspections of austenitic cladding by means of pancake probes. Phase and amplitude characteristics of artificial defects and anticipated interference signals. Optimization of inspection parameters
MEASUREMENTS AND MODELING OF EDDY CURRENT EFFECTS IN BNL'S AGS BOOSTER
International Nuclear Information System (INIS)
BROWN, K.A.; AHRENS, L.; GARDNER, C.; GLENN, J.W.; HARVEY, M.; MENG, W.; ZENO, K.
2006-01-01
Recent beam experiments at BNL's AGS Booster have enabled us to study in more detail the effects of eddy currents on the lattice structure and our control over the betatron tune. The Booster is capable of operating at ramp rates as high as 9 T/sec. At these ramp rates eddy currents in the vacuum chambers significantly alter the fields and gradients seen by the beam as it is accelerated. The Booster was designed with these effects in mind and to help control the field uniformity and linearity in the Booster Dipoles special vacuum chambers were designed with current windings to negate the affect of the induced eddy currents. In this report results from betatron tune measurements and eddy current simulations will be presented. We will then present results from modeling the accelerator using the results of the magnetic field simulations and compare these to the measurements
International Nuclear Information System (INIS)
Han, Hui; Balcom, Bruce J
2011-01-01
Magnetic resonance imaging (MRI) measurements inside cylindrical metal structures have recently been proposed and form the basis for new high-pressure MRI studies. The critical problem for MRI inside cylindrical metal structures is significant eddy currents induced by the switched magnetic field gradients, which usually corrupt spatial and motion encoding without appropriate correction. In this work a so-called standard SPRITE (single point ramped imaging with T 1 enhancement) technique is applied for imaging inside cylindrical metal structures. We show that the standard SPRITE technique is fundamentally immune to large-scale eddy current effects and yields artifact-free high-quality images with no eddy current correction required. Standard SPRITE image acquisition avoids the complications involved in the measurement and compensation of eddy current effects for MRI with cylindrical metal structures. This work is a substantial advance toward the extension of MRI to new challenging systems, which are of practical importance
Eddy current imaging for electrical characterization of silicon solar cells and TCO layers
Hwang, Byungguk; Hillmann, Susanne; Schulze, Martin; Klein, Marcus; Heuer, Henning
2015-03-01
Eddy Current Testing has been mainly used to determine defects of conductive materials and wall thicknesses in heavy industries such as construction or aerospace. Recently, high frequency Eddy Current imaging technology was developed. This enables the acquirement of information of different depth level in conductive thin-film structures by realizing proper standard penetration depth. In this paper, we summarize the state of the art applications focusing on PV industry and extend the analysis implementing achievements by applying spatially resolved Eddy Current Testing. The specific state of frequency and complex phase angle rotation demonstrates diverse defects from front to back side of silicon solar cells and characterizes homogeneity of sheet resistance in Transparent Conductive Oxide (TCO) layers. In order to verify technical feasibility, measurement results from the Multi Parameter Eddy Current Scanner, MPECS are compared to the results from Electroluminescence.
A Method for Eddy Current Field Measurement in Permanent Magnet Magnetic Resonance Imaging Systems
Directory of Open Access Journals (Sweden)
SONG Rui
2018-03-01
Full Text Available Magnetic resonance imaging (MRI is a widely used medical imaging technique. In MRI system, gradient magnetic fields are used to code spatial information. However, the fast-switching electric currents in the gradients coils used to generate gradient fields also induce vortex electric field, often referred as eddy current, in the surrounding metal conductors. In this paper, a method for eddy current field measurement was proposed. Based on the Faraday law of electromagnetic induction, an eddy current field measuring device was designed. Combining hardware acquisition and software processing, the eddy current field was obtained by subtracting the ideal gradient field from the magnetic field measured experimentally, whose waveform could be displayed in real time. The proposed method was verified by experimental results.
Ozkaya, Efe; Yilmaz, Cetin
2017-02-01
The effect of eddy current damping on a novel locally resonant periodic structure is investigated. The frequency response characteristics are obtained by using a lumped parameter and a finite element model. In order to obtain wide band gaps at low frequencies, the periodic structure is optimized according to certain constraints, such as mass distribution in the unit cell, lower limit of the band gap, stiffness between the components in the unit cell, the size of magnets used for eddy current damping, and the number of unit cells in the periodic structure. Then, the locally resonant periodic structure with eddy current damping is manufactured and its experimental frequency response is obtained. The frequency response results obtained analytically, numerically and experimentally match quite well. The inclusion of eddy current damping to the periodic structure decreases amplitudes of resonance peaks without disturbing stop band width.
Automatic appraisal of defects in irradiated pins by eddy current testing
International Nuclear Information System (INIS)
Marsol, R.; Cornu, B.
1986-10-01
Eddy current testing is very efficient to inspect the sheaths of spent fuel elements. Automation of the process is developed to replace visual examination of recorded eddy current signals. The method is applied to austenitic steel fuel cans for fast neutron reactors to detect cracks, voids, inclusions... The different types of defects and experimental processes are recalled then automatic detection and the method for defect qualification are presented [fr
Effects of Angular Variation on Split D Differential Eddy Current Probe Response (Postprint)
2016-02-10
AFRL-RX-WP-JA-2016-0327 EFFECTS OF ANGULAR VARIATION ON SPLIT D DIFFERENTIAL EDDY CURRENT PROBE RESPONSE (POSTPRINT) Ryan D...March 2014 – 22 September 2015 4. TITLE AND SUBTITLE EFFECTS OF ANGULAR VARIATION ON SPLIT D DIFFERENTIAL EDDY CURRENT PROBE RESPONSE (POSTPRINT... Current Probe Response Ryan D. Mooers1, a) and John C. Aldrin2 1United States Air Force Research Labs, Materials and Manufacturing Directorate, Structural
International Nuclear Information System (INIS)
Paillard, S.
2007-12-01
One of the Eddy Current Testing issues in aeronautics is the inspection of fastened structures to detect flaws nearby rivets which can grow because of mechanical stress. EADS and the CEA LIST have started a collaborative work with the support of the Ile-de-France Region to develop a simulation tool of EC fastened structures testing, integrated to the CIVA platform, aimed at conceiving testing methods, optimizing and qualifying it. The volume integral method using the Green dyadics formalism has been chosen in order to get a fast resolution of Maxwell equations. A first milestone was to build a simulation model of multilayer structures testing, thanks to the use of the multilayer Green dyads. Because of the rivet volume, 60 times bigger than the one of a typical flaw, a large number of discretization cells are needed. Therefore an iterative method has been developed in order to numerically solve large calculation zones. Finally, the flaw response simulation mostly has to cope with a scale issue between the size of the rivet and the one of the flaw, the latter being much smaller in a direction than the former. The whole model has been experimentally validated and compared to other simulation models at the important development steps: multilayer configuration, iteration resolution, and flaw signature. (author)
Use of time space Green's functions in the computation of transient eddy current fields
International Nuclear Information System (INIS)
Davey, K.; Turner, L.
1988-01-01
The utility of integral equations to solve eddy current problems has been borne out by numerous computations in the past few years, principally in sinusoidal steady-state problems. This paper attempts to examine the applicability of the integral approaches in both time and space for the more generic transient problem. The basic formulation for the time space Green's function approach is laid out. A technique employing Gauss-Laguerre integration is employed to realize the temporal solution, while Gauss--Legendre integration is used to resolve the spatial field character. The technique is then applied to the fusion electromagnetic induction experiments (FELIX) cylinder experiments in both two and three dimensions. It is found that quite accurate solutions can be obtained using rather coarse time steps and very few unknowns; the three-dimensional field solution worked out in this context used basically only four unknowns. The solution appears to be somewhat sensitive to the choice of time step, a consequence of a numerical instability imbedded in the Green's function near the origin
Zhang, S.; Rem, P.C.; Forssberg, E.
1999-01-01
Owing to the growing emergence of the end-of-life electrical and electronic products with complex material structures and an ever-diminishing particle size of the valuable metals involved, development of eddy current separators (ECS) has been targeting selective separation of small non-ferrous metal
International Nuclear Information System (INIS)
Sullivan, S.P.; Cecco, V.S.; Carter, J.R.; Spanner, M.; McElvanney, M.; Krause, T.W.; Tkaczyk, R.
2000-01-01
Licensing requirements for eddy current inspections for nuclear steam generators and heat exchangers are becoming increasingly stringent. The traditional industry-standard method of comparing inspection signals with flaw signals from simple in-line calibration standards is proving to be inadequate. A more complete understanding of eddy current and magnetic field interactions with flaws and other anomalies is required for the industry to generate consistently reliable inspections. Computer modeling is a valuable tool in improving the reliability of eddy current signal analysis. Results from computer modeling are helping inspectors to properly discriminate between real flaw signals and false calls, and improving reliability in flaw sizing. This presentation will discuss complementary eddy current computer modeling techniques such as the Finite Element Method (FEM), Volume Integral Method (VIM), Layer Approximation and other analytic methods. Each of these methods have advantages and limitations. An extension of the Layer Approximation to model eddy current probe responses to ferromagnetic materials will also be presented. Finally examples will be discussed demonstrating how some significant eddy current signal analysis problems have been resolved using appropriate electromagnetic computer modeling tools
Coupling between angular deflection and eddy currents in the FELIX plate experiment
International Nuclear Information System (INIS)
Turner, L.R.; Cuthbertson, J.W.
1983-08-01
For a conducting body experiencing superimposed changing and steady magnetic field, for example a limiter in a tokamak during plasma quench, the induced eddy currents and the deflections resulting from those eddy currents are coupled. Experimental study of these coupled deflections and currents can be performed with the FELIX (Fusion Electromagnetic Induction Experiment) facility nearing completion at ANL. Predictions of the coupling are described, as computed with the code EDDYNET, which has been modified for this purpose. Effects of the coupling will be readily observable experimentally. In the FELIX plate experiment, the coupling between deflection and eddy currents was readily calculated because the rigid-body rotation of the plate is equivalent to a contrarotation of the applied magnetic fields. For a geometry such as a plasma limiter, in which the eddy currents would cause a deformation of the conducting body, an analysis of the coupling between eddy currents and deformation would require a structural-analysis code and an eddy current code to be simultaneously computing from the same mesh
A gradient based algorithm to solve inverse plane bimodular problems of identification
Ran, Chunjiang; Yang, Haitian; Zhang, Guoqing
2018-02-01
This paper presents a gradient based algorithm to solve inverse plane bimodular problems of identifying constitutive parameters, including tensile/compressive moduli and tensile/compressive Poisson's ratios. For the forward bimodular problem, a FE tangent stiffness matrix is derived facilitating the implementation of gradient based algorithms, for the inverse bimodular problem of identification, a two-level sensitivity analysis based strategy is proposed. Numerical verification in term of accuracy and efficiency is provided, and the impacts of initial guess, number of measurement points, regional inhomogeneity, and noisy data on the identification are taken into accounts.
Acoustic 2D full waveform inversion to solve gas cloud challenges
Directory of Open Access Journals (Sweden)
Srichand Prajapati
2015-09-01
Full Text Available The existing conventional inversion algorithm does not provide satisfactory results due to the complexity of propagated wavefield though the gas cloud. Acoustic full waveform inversion has been developed and applied to a realistic synthetic offshore shallow gas cloud feature with Student-t approach, with and without simultaneous sources encoding. As a modeling operator, we implemented the grid based finite-difference method in frequency domain using second order elastic wave equation. Jacobin operator and its adjoint provide a necessary platform for solving full waveform inversion problem in a reduced Hessian matrix. We invert gas cloud model in 5 frequency band selected from 1 to 12 Hz, each band contains 3 frequencies. The inversion results are highly sensitive to the misfit. The model allows better convergence and recovery of amplitude losses. This approach gives better resolution then the existing least-squares approach. In this paper, we implement the full waveform inversion for low frequency model with minimum number of iteration providing a better resolution of inversion results.
International Nuclear Information System (INIS)
Joubert, P.Y.; Madaoui, N.
1999-01-01
In the context of eddy current non destructive evaluation using a tomographic image reconstruction process, the success of the reconstruction depends not only on the choice of the forward model and of the inversion algorithms, but also on the ability to extract the pertinent data from the raw signal provided by the sensor. We present in this paper, an experimental device designed for imaging purposes, the corresponding forward model, and a pre-processing of the experimental data using wavelet analysis. These three steps implemented with an inversion algorithm, will allow in the future to perform image reconstruction of 3-D flaws. (authors)
Gross, Lutz; Altinay, Cihan; Fenwick, Joel; Smith, Troy
2014-05-01
The program package escript has been designed for solving mathematical modeling problems using python, see Gross et al. (2013). Its development and maintenance has been funded by the Australian Commonwealth to provide open source software infrastructure for the Australian Earth Science community (recent funding by the Australian Geophysical Observing System EIF (AGOS) and the AuScope Collaborative Research Infrastructure Scheme (CRIS)). The key concepts of escript are based on the terminology of spatial functions and partial differential equations (PDEs) - an approach providing abstraction from the underlying spatial discretization method (i.e. the finite element method (FEM)). This feature presents a programming environment to the user which is easy to use even for complex models. Due to the fact that implementations are independent from data structures simulations are easily portable across desktop computers and scalable compute clusters without modifications to the program code. escript has been successfully applied in a variety of applications including modeling mantel convection, melting processes, volcanic flow, earthquakes, faulting, multi-phase flow, block caving and mineralization (see Poulet et al. 2013). The recent escript release (see Gross et al. (2013)) provides an open framework for solving joint inversion problems for geophysical data sets (potential field, seismic and electro-magnetic). The strategy bases on the idea to formulate the inversion problem as an optimization problem with PDE constraints where the cost function is defined by the data defect and the regularization term for the rock properties, see Gross & Kemp (2013). This approach of first-optimize-then-discretize avoids the assemblage of the - in general- dense sensitivity matrix as used in conventional approaches where discrete programming techniques are applied to the discretized problem (first-discretize-then-optimize). In this paper we will discuss the mathematical framework for
Automation of eddy current system for in-service inspection of turbine and generator bores
International Nuclear Information System (INIS)
Viertl, J.R.M.
1988-01-01
The most commonly applied inspection method for ferromagnetic turbine and generator rotor bores is the magnetic particle test technique. This method is subjective, depends on the test operator's skill and diligence in identifying test indications, and suffers from poor repeatability, especially for small indications. Automation would improve repeatability. However, magnetic particle tests are not easily automated, because the data are in the form of sketches, photographs, and written and oral descriptions of the indications. Eddy current inspection has obvious potential to replace magnetic particle methods in this application. Eddy current tests can be readily automated, as the data are in the form of voltages that can be recorded, digitized, and manipulated by a computer. The current project continues the investigation of the correlation between eddy current and magnetic particle inspection. Two systems have been combined to acquire eddy current data automatically. This combination of systems consists of the Nortec-25L Eddyscope (to provide the analog eddy current signals) and the General Electric DATAQ (TM) System (to perform the automatic data acquisition). The automation of the system is discussed
International Nuclear Information System (INIS)
Upadhyaya, B.R.; Yan, W.; Henry, G.
1999-01-01
A diagnostic expert system that integrates database management methods, artificial neural networks, and decision-making using fuzzy logic has been developed for the automation of steam generator eddy current test (ECT) data analysis. The new system, known as EDDYAI, considers the following key issues: (1) digital eddy current test data calibration, compression, and representation; (2) development of robust neural networks with low probability of misclassification for flaw depth estimation; (3) flaw detection using fuzzy logic; (4) development of an expert system for database management, compilation of a trained neural network library, and a decision module; and (5) evaluation of the integrated approach using eddy current data. The implementation to field test data includes the selection of proper feature vectors for ECT data analysis, development of a methodology for large eddy current database management, artificial neural networks for flaw depth estimation, and a fuzzy logic decision algorithm for flaw detection. A large eddy current inspection database from the Electric Power Research Institute NDE Center is being utilized in this research towards the development of an expert system for steam generator tube diagnosis. The integration of ECT data pre-processing as part of the data management, fuzzy logic flaw detection technique, and tube defect parameter estimation using artificial neural networks are the fundamental contributions of this research. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Upadhyaya, B.R.; Yan, W. [Tennessee Univ., Knoxville, TN (United States). Dept. of Nuclear Engineering; Behravesh, M.M. [Electric Power Research Institute, Palo Alto, CA (United States); Henry, G. [EPRI NDE Center, Charlotte, NC (United States)
1999-09-01
A diagnostic expert system that integrates database management methods, artificial neural networks, and decision-making using fuzzy logic has been developed for the automation of steam generator eddy current test (ECT) data analysis. The new system, known as EDDYAI, considers the following key issues: (1) digital eddy current test data calibration, compression, and representation; (2) development of robust neural networks with low probability of misclassification for flaw depth estimation; (3) flaw detection using fuzzy logic; (4) development of an expert system for database management, compilation of a trained neural network library, and a decision module; and (5) evaluation of the integrated approach using eddy current data. The implementation to field test data includes the selection of proper feature vectors for ECT data analysis, development of a methodology for large eddy current database management, artificial neural networks for flaw depth estimation, and a fuzzy logic decision algorithm for flaw detection. A large eddy current inspection database from the Electric Power Research Institute NDE Center is being utilized in this research towards the development of an expert system for steam generator tube diagnosis. The integration of ECT data pre-processing as part of the data management, fuzzy logic flaw detection technique, and tube defect parameter estimation using artificial neural networks are the fundamental contributions of this research. (orig.)
An application of eddy current damping effect on single point diamond turning of titanium alloys
Yip, W. S.; To, S.
2017-11-01
Titanium alloys Ti6Al4V (TC4) have been popularly applied in many industries. They have superior material properties including an excellent strength-to-weight ratio and corrosion resistance. However, they are regarded as difficult to cut materials; serious tool wear, a high level of cutting vibration and low surface integrity are always involved in machining processes especially in ultra-precision machining (UPM). In this paper, a novel hybrid machining technology using an eddy current damping effect is firstly introduced in UPM to suppress machining vibration and improve the machining performance of titanium alloys. A magnetic field was superimposed on samples during single point diamond turning (SPDT) by exposing the samples in between two permanent magnets. When the titanium alloys were rotated within a magnetic field in the SPDT, an eddy current was generated through a stationary magnetic field inside the titanium alloys. An eddy current generated its own magnetic field with the opposite direction of the external magnetic field leading a repulsive force, compensating for the machining vibration induced by the turning process. The experimental results showed a remarkable improvement in cutting force variation, a significant reduction in adhesive tool wear and an extreme long chip formation in comparison to normal SPDT of titanium alloys, suggesting the enhancement of the machinability of titanium alloys using an eddy current damping effect. An eddy current damping effect was firstly introduced in the area of UPM to deliver the results of outstanding machining performance.
An application of eddy current damping effect on single point diamond turning of titanium alloys
International Nuclear Information System (INIS)
Yip, W S; To, S
2017-01-01
Titanium alloys Ti6Al4V (TC4) have been popularly applied in many industries. They have superior material properties including an excellent strength-to-weight ratio and corrosion resistance. However, they are regarded as difficult to cut materials; serious tool wear, a high level of cutting vibration and low surface integrity are always involved in machining processes especially in ultra-precision machining (UPM). In this paper, a novel hybrid machining technology using an eddy current damping effect is firstly introduced in UPM to suppress machining vibration and improve the machining performance of titanium alloys. A magnetic field was superimposed on samples during single point diamond turning (SPDT) by exposing the samples in between two permanent magnets. When the titanium alloys were rotated within a magnetic field in the SPDT, an eddy current was generated through a stationary magnetic field inside the titanium alloys. An eddy current generated its own magnetic field with the opposite direction of the external magnetic field leading a repulsive force, compensating for the machining vibration induced by the turning process. The experimental results showed a remarkable improvement in cutting force variation, a significant reduction in adhesive tool wear and an extreme long chip formation in comparison to normal SPDT of titanium alloys, suggesting the enhancement of the machinability of titanium alloys using an eddy current damping effect. An eddy current damping effect was firstly introduced in the area of UPM to deliver the results of outstanding machining performance. (paper)
Directory of Open Access Journals (Sweden)
Hui Zhang
2017-03-01
Full Text Available This paper analyzes and compares models for predicting average magnet losses in interior permanent-magnet motors with fractional-slot concentrated windings due to harmonics in the armature reaction (assuming sinusoidal phase currents. Particularly, loss models adopting different formulations and solutions to the Helmholtz equation to solve for the eddy currents are compared to a simpler model relying on an assumed eddy-current distribution. Boundaries in terms of magnet dimensions and angular frequency are identified (numerically and using an identified approximate analytical expression to aid the machine designer whether the more simple loss model is applicable or not. The assumption of a uniform flux-density variation (used in the loss models is also investigated for the case of V-shaped and straight interior permanent magnets. Finally, predicted volumetric loss densities are exemplified for combinations of slot and pole numbers common in automotive applications.
Multifrequency eddy-current inspection of seam weld in steel sheath
Energy Technology Data Exchange (ETDEWEB)
Smith, J.H.; Dodd, C.V.; Chitwood, L.D.
1985-04-01
Multifrequency eddy-current techniques were used to perform a continuous on-line inspection of the seam weld in the steel jacket for a superconducting cable. The inspection was required to detect both surface and internal weld flaws in the presence of a large, highly conductive central conductor. Raw eddy-current data were recorded on magnetic tape, and test properties such as discontinuity size and weld penetration were determined by mathematically fitting these data to coefficients developed with representative standards. A sophisticated computer-controlled scanning technique was applied, and a unique scanning device was developed to provide full coverage of the weld and heat-affected zone. The techniques used to develop this multifrequency eddy-current examination are described in this report along with the test equipment, test procedures, and computer programs.
Multifrequency eddy-current inspection of seam weld in steel sheath
International Nuclear Information System (INIS)
Smith, J.H.; Dodd, C.V.; Chitwood, L.D.
1985-04-01
Multifrequency eddy-current techniques were used to perform a continuous on-line inspection of the seam weld in the steel jacket for a superconducting cable. The inspection was required to detect both surface and internal weld flaws in the presence of a large, highly conductive central conductor. Raw eddy-current data were recorded on magnetic tape, and test properties such as discontinuity size and weld penetration were determined by mathematically fitting these data to coefficients developed with representative standards. A sophisticated computer-controlled scanning technique was applied, and a unique scanning device was developed to provide full coverage of the weld and heat-affected zone. The techniques used to develop this multifrequency eddy-current examination are described in this report along with the test equipment, test procedures, and computer programs
Characterisation of eddy current signals using different types of artificial neural networks
International Nuclear Information System (INIS)
Shyamsunder, M.T.; Rajagopalan, C.; Jayakumar, T.; Kalyanasundaram, P.; Baldev Raj; Ray, K.K.
1996-01-01
Eddy current testing is one of the important techniques in nondestructive testing. Automated characterisation of eddy current signals (ECS), either in the form of lissajous patterns (figure-of-eight) or individual voltage vs. time signals is an area of growing interest. This is particularly relevant in environments where the signal-to-noise ratio (SNR) of ECS are very poor. Intelligent, timely and precise interpretation of resulting data, is the key for improving the efficiency of NDT and E. A comprehensive study has been undertaken by the authors for the characterisation of ECS having poor SNR, using three types of artificial neural networks (ANNs). The types of ANNs used in this study are [a] the error-back propagation model, [b] the binary Hopfield model and [c] the Kohonen's self-organising maps model. Eddy current signals, acquired from different types of defects such as holes and notches on stainless steel type 316 sheets were used in this study. (author)
Research of Steel-dielectric Transition Using Subminiature Eddy-current Transducer
Dmitriev, S. F.; Malikov, V. N.; Sagalakov, A. M.; Ishkov, A. V.
2018-05-01
The research aims to develop a subminiature transducer for electrical steel investigation. The authors determined the capability to study steel characteristics at different depths based on variations of eddy-current transducer amplitude at the steel-dielectric boundary. A subminiature transformer-type transducer was designed, which enables to perform local investigations of ferromagnetic materials using an eddy-current method based on local studies of the steel electrical conductivity. Having the designed transducer as a basis, a hardware-software complex was built to perform experimental studies of steel at the interface boundary. Test results are reported for a specimen with continuous and discrete measurements taken at different frequencies. The article provides the key technical information about the eddy current transformer used and describes the methodology of measurements that makes it possible to control steel to dielectric transition.
Application of numerical analysis techniques to eddy current testing for steam generator tubes
International Nuclear Information System (INIS)
Morimoto, Kazuo; Satake, Koji; Araki, Yasui; Morimura, Koichi; Tanaka, Michio; Shimizu, Naoya; Iwahashi, Yoichi
1994-01-01
This paper describes the application of numerical analysis to eddy current testing (ECT) for steam generator tubes. A symmetrical and three-dimensional sinusoidal steady state eddy current analysis code was developed. This code is formulated by future element method-boundary element method coupling techniques, in order not to regenerate the mesh data in the tube domain at every movement of the probe. The calculations were carried out under various conditions including those for various probe types, defect orientations and so on. Compared with the experimental data, it was shown that it is feasible to apply this code to actual use. Furthermore, we have developed a total eddy current analysis system which consists of an ECT calculation code, an automatic mesh generator for analysis, a database and display software for calculated results. ((orig.))
Determination of crack depth in aluminum using eddy currents and GMR sensors
Lopes Ribeiro, A.; Pasadas, D.; Ramos, H. G.; Rocha, T.
2015-03-01
In this paper we use eddy currents to determine the depth of linear cracks in aluminum plates. A constant field probe is used to generate the spatially uniform excitation field and a single axis giant magneto-resistor (GMR) sensor is used to measure the eddy currents magnetic field. Different depths were machined in one aluminum plate with 4 mm of thickness. By scanning those cracks the magnetic field components parallel and perpendicular to the crack's line were measured when the eddy currents were launched perpendicularly to the crack's line. To characterize one crack in a plate of a given thickness and material, the experimental procedure was defined. The plate surface is scanned to detect and locate one crack. The acquired data enables the determination of the crack's length and orientation. A second scanning is performed with the excitation current perpendicular to the crack and the GMR sensing axis perpendicular and parallel to the crack's line.
Motion-induced eddy current thermography for high-speed inspection
Directory of Open Access Journals (Sweden)
Jianbo Wu
2017-08-01
Full Text Available This letter proposes a novel motion-induced eddy current based thermography (MIECT for high-speed inspection. In contrast to conventional eddy current thermography (ECT based on a time-varying magnetic field created by an AC coil, the motion-induced eddy current is induced by the relative motion between magnetic field and inspected objects. A rotating magnetic field created by three-phase windings is used to investigate the heating principle and feasibility of the proposed method. Firstly, based on Faraday’s law the distribution of MIEC is investigated, which is then validated by numerical simulation. Further, experimental studies are conducted to validate the proposed method by creating rotating magnetic fields at different speeds from 600 rpm to 6000 rpm, and it is verified that rotating speed will increase MIEC intensity and thereafter improve the heating efficiency. The conclusion can be preliminarily drawn that the proposed MIECT is a platform suitable for high-speed inspection.
Application of eddy current inspection to the Inconel weld of BWR internals
International Nuclear Information System (INIS)
Machida, Eiji; Yusa, Noritaka
2004-01-01
In order to definite the basic specifications of application of ECT (Eddy Current Test) to Inconel weld of BWR internals, the inspection and numerical analysis were carried out. The characteristics of the existing ECT probe were studied by making sample as same as CRD stud tube, measuring the relative permeability and electric conductivity of Inconel and alloy and evaluating ECT probe. On the basis of the results obtained, the basic specifications were determined and a new eddy current probe for inspection was designed and produced. The new ECT probe was able to detect small notch in Inconel weld, to classify the defects by eddy current inspection signal and sizing the length and depth. It is concluded that the new ECT probe is able to apply the Inconel weld of BWR internals. (S.Y.)
Evaluation and field validation of Eddy-Current array probes for steam generator tube inspection
International Nuclear Information System (INIS)
Dodd, C.V.; Pate, J.R.
1996-07-01
The objective of the Improved Eddy-Current ISI for Steam Generator Tubing program is to upgrade and validate eddy-current inspections, including probes, instrumentation, and data processing techniques for inservice inspection of new, used, and repaired steam generator tubes; to improve defect detection, classification, and characterization as affected by diameter and thickness variations, denting, probe wobble, tube sheet, tube supports, copper and sludge deposits, even when defect types and other variables occur in combination; to transfer this advanced technology to NRC's mobile NDE laboratory and staff. This report describes the design of specialized high-speed 16-coil eddy-current array probes. Both pancake and reflection coils are considered. Test results from inspections using the probes in working steam generators are given. Computer programs developed for probe calculations are also supplied
Eddy currents in a nonperiodic vacuum vessel induced by axisymmetric plasma motion
International Nuclear Information System (INIS)
DeLucia, J.
1985-12-01
A method is described for calculating the two-dimensional trajectory of a vertically or horizontally unstable axisymmetric tokamak plasma in the presence of a resistive vacuum vessel. The vessel is not assumed to have toroidal symmetry. The plasma is represented by a current-filament loop that is free to move vertically and to change its major radius. Its position is evolved in time self-consistently with the vacuum vessel eddy currents. The plasma current, internal inductance, and poloidal beta can be specified functions of time so that eddy currents resulting from a disruption can be modeled. The vacuum vessel is represented by a set of current-filaments whose positions and orientations are chosen to model the dominant eddy current paths. Although the specific application is to TFTR, the present model is of general applicability. 7 refs., 4 figs., 2 tabs
Development of an eddy current inspection technique for sleeved engine disk bolt holes
International Nuclear Information System (INIS)
Palanisamy, R.; Lakin, K.M.
1983-01-01
Recent research programs have concentrated mainly on developing techniques to characterize surface breaking cracks and very little has been done towards characterizing subsurface flaws in conducting materials. Presented in this paper are the results of some initial theoretical work aimed at the development of a reliable eddy current technique to detect and characterize defects in engine disk bolt holes under a 0.05'' stainless steel sleeve. The change in impedance of an absolute eddy current coil with and without ferrite core, and the distribution of eddy currents around a second layer crack with and without a thin insulating film between the two conducting layers have been predicted numerically. The overall system development goals and methods to accomplish them are outlined briefly
Application of an eddy current technique to steam generator U-bend characterization. Final report
International Nuclear Information System (INIS)
Cramer, W.E.; de la Pintiere, L.; Narita, S.; Bergander, M.J.
1982-04-01
Eddy current nondestructive testing techniques are used widely throughout the utility industry for the early detection of tube damage in critical power plant components such as steam generators. In this project, the application of an eddy current technique for the characterization of U-bend transitions in the first row tubing in Westinghouse 51 Series Steam Generators has been investigated. A method has been developed for detection of the opposite transition in the U-bend and for defining its severity. Investigation included two different types of U-bend transitions. Using the developed eddy current method for U-bend characterization, on-site inspection was performed on all tubes in the first row in four 51 Series steam generators in Power Plant Unit No. 2 and in one 51 Series steam generator in Power Plant Unit No. 1. The advantages and limitations of the developed method as well as the recommendations for further investigations are included
Energy Technology Data Exchange (ETDEWEB)
Midtgaard, Ole-Morten
1997-12-31
This thesis considers the feasibility of doing calculations to optimize electrical machines without the need to build expensive prototypes. It deals with the construction and assessment of new, hierarchical, hexahedral edge elements for three-dimensional computations of eddy currents with the electric vector potential formulation. The new elements, five in all, gave up to second-order approximations for both the magnetic field and the current density. Theoretical arguments showed these elements to be more economical for a given polynomial order of the approximated fields than the serendipity family of nodal elements. Further it was pointed out how the support of a source field computed by using edge elements could be made very small provided that a proper spanning tree was used in the edge element mesh. This was exploited for the voltage forcing technique, where source fields were used as basis functions, with unknown total currents in voltage forced conductors as degrees of freedom. The practical assessment of the edge elements proved the accuracy to improve with increasing polynomial order, both for local and global quantities. The most economical element was, however, one giving only complete first-order approximations for both fields. Further, the edge elements turned out to be better than the nodal elements also in practice. For the voltage forcing technique, source field basis functions which had small support, resulted in large reduction of the CPU-time for solving the main equation system, compared to source fields which had large support. The new elements can be used in a p-type adaptive scheme, and they should also be applicable for other tangentially continuous field problems. 67 refs., 34 figs., 10 tabs.
The count of losses by eddy currents in the windings of electric motors with hollow anchor
Directory of Open Access Journals (Sweden)
N. V. Pribylova
2017-01-01
Full Text Available Given the rationale of taking into account losses on eddy currents in the windings of a low-inertia DC motors with offered magnetoelectric systems. Increased in recent years, the power of these motors (through the use of highly coercive magnets permanent caused an increase in the volume of copper in the air gap and the magnetic induction values. All this has values given rise to significant eddy currents in the windings made in the air gap, and hence the necessity of taking into account losses from these currents. The experimentally obtained dependence of the losses on eddy currents on the frequency of rotation for a DC motor with a hollow anchor with a power of 350 watts. The magnitude of these losses can reach 30% of the nominal power of the motor. Described mechanism of occurrence of losses. Eddy currents occur in areas with variable magnetic flux and cause the appearance of force, which is directed toward the velocity vector and inhibits the anchor. The directions of these currents, the vectors of magnetic induction, magnetic field and force acting on the conductor winding and a braking anchor. The proposed methods reduce losses: crushing contours of eddy currents and achieve uniform distribution of magnetic induction in the interpolar space of the motor. Shows their strengths and weaknesses. The crushing circuits of windings occur surge currents. To eliminate the losses on the surge currents it is necessary to apply a transposition of the conductors. Given a refined formula for finding the losses on eddy currents in the armature winding, the conductors of which is made in the form of a harness of several wires. Formula has shown a good convergence with experimental data.
International Nuclear Information System (INIS)
Bennoud, S; Zergoug, M
2015-01-01
It has been shown that the eddy current method is one of the most effective techniques for the detection and characterization of surface and near-surface defects in conductive mediums especially in aluminum alloy. It is one of the most applied methods in industries which require a maximum of reliability and security (aerospace, aeronautics, nuclear, Etc). In this study, a code to solve electromagnetic problems by employing the finite element method is developed. The suggested model can simulate the probe response to the presence of a defect hidden in a multi-layered structure or a riveted structure on aluminum alloy. The developed code is based on the discretization in three dimensions of the Maxwell's equations in harmonic mode by the finite element method based on the combined potential formulations. That will enable us to interpret the results, to present them in graphical form and to carry out simulations for various applications
Compulsory Checking of Nuclear Power Engineering Materials by Direct and Eddy Current
Larionov, V. V.; Lider, A. M.; Sednev, D. A.; Xu, Shupeng
2016-08-01
The testing technology of copper parts designed for dry storage of spent nuclear fuel with application of direct and eddy current has been developed. Measurements results of flaw quantity caused hydrogenation and oxidation processes are presented. Evolution of copper M 001 flaw structure during hydrogenation from gaseous medium is analyzed. It has been demonstrated that the dependence of copper p electrical resistance on number of flaws in its structure has dome shaped character and changes with eddy current frequency change. Number of flaws formed by hydrogen depends on direction (100) or (200) of the crystal structure of copper lattice.
Multifrequency Eddy current testing of heat exchange tubes with a rotating probe
International Nuclear Information System (INIS)
Levy, R.
1982-01-01
Multi-frequency eddy current analyses have been used in France industrially since 1975. In light of the experienced gained during many steam generator inspections, this technique was applied to the examination of sheet and tube heat exchangers featuring tubes in very different materials such as copper, stainless steel and titanium. The principle of multi-frequency Eddy current inspection is first reviewed, using the example of a condenser with nickel alloy tubes (Inconel, Incoloy). This is followed by the description of a specific application of this technique to a condenser with titanium tubes, analyzed with a rotating local probe [fr
Vessel Eddy Current Measurement for the National Spherical Torus Experiment (NSTX)
International Nuclear Information System (INIS)
Gates, D.A.; Menard, J.; Marsala, R.
2004-01-01
A simple analog circuit that measures the NSTX axisymmetric eddy current distribution has been designed and constructed. It is based on simple circuit model of the NSTX vacuum vessel that was calibrated using a special axisymmetric eddy current code which was written so that accuracy was maintained in the vicinity of the current filaments. The measurement and the model have been benchmarked against data from numerous vacuum shots and they are in excellent agreement. This is an important measurement that helps give more accurate equilibrium reconstructions
International Nuclear Information System (INIS)
Rao, B.P.C.; Thirunavukkarasu, S.; Sasi, B.; Jayakumar, T.; Baldev Raj
2010-01-01
Eddy current non-destructive evaluation (NDE) techniques find many applications during fabrication and in-service inspection of components made of stainless steel. In recent years, concurrent developments in electromagnetic field detection sensors such as giant magneto-resistive (GMR), giant-magneto impedance (GMI) and SQUIDs sensors, computers, microelectronics, and incorporating advanced signal and image processing techniques, have paved the way for enhancing the capabilities of existing eddy current (EC) techniques for examination of austenitic stainless steel (SS) plates, tubes and other geometries and several innovative methodologies have been developed. This paper highlights a few such applications in EC testing to austenitic stainless steel components used in fast reactors. (author)
A constitutive model for the forces of a magnetic bearing including eddy currents
Taylor, D. L.; Hebbale, K. V.
1993-01-01
A multiple magnet bearing can be developed from N individual electromagnets. The constitutive relationships for a single magnet in such a bearing is presented. Analytical expressions are developed for a magnet with poles arranged circumferencially. Maxwell's field equations are used so the model easily includes the effects of induced eddy currents due to the rotation of the journal. Eddy currents must be included in any dynamic model because they are the only speed dependent parameter and may lead to a critical speed for the bearing. The model is applicable to bearings using attraction or repulsion.
International Nuclear Information System (INIS)
Buck, J.; Underhill, P.R.; Mokros, S.G.; Morelli, J.; Krause, T.W.; Babbar, V.K.; Lepine, B.
2015-01-01
Nuclear steam generator (SG) support structure degradation and fouling can result in damage to SG tubes and loss of SG efficiency. Conventional eddy current technology is extensively used to detect cracks, frets at supports and other flaws, but has limited capabilities in the presence of multiple degradation modes or fouling. Pulsed eddy current (PEC) combined with principal components analysis (PCA) and multiple linear regression models was examined for the inspection of support structure degradation and SG tube off-centering with the goal of extending results to include additional degradation modes. (author)
Eddy-current inspection of high flux isotope reactor nuclear control rods
International Nuclear Information System (INIS)
Smith, J.H.; Chitwood, L.D.
1981-07-01
Inner control rods for the High Flux Isotope Reactor were nondestructively inspected for defects by eddy-current techniques. During these examinations aluminum cladding thickness and oxide thickness on the cladding were also measured. Special application techniques were required because of the high-radiation levels (approx. 10 5 R/h at 30 cm) present and the relatively large temperature gradients that occurred on the surface of the control rods. The techniques used to perform the eddy-current inspections and the methods used to reduce the associated data are described
Eddy current inspection of tubing; Inspeccion de tubos por corrientes de Foucault
Energy Technology Data Exchange (ETDEWEB)
Bauza, J L. R.; Herrero, J; Diaz, J
1966-07-01
The Experimental research work carried out to develop a Eddy current testing equipment is described. Search coils with ferrite or air cores were used and the obtained results are discussed. Valuable information was gained from a improved channel in which a direct measure of the defect and the reference signal phase difference is obtained. Artificial defect used to evaluate resolution and sensitivity were produced by electro-machining and mechanical means. Finned SAP tubing was tested in a routine basis with the described equipment and the results plotted. Basic and theoretical considerations on the Eddy current testing technique are given in the last section of this report. (Author)
Basic research into eddy current testing of austenetic weld joints and surface claddings
International Nuclear Information System (INIS)
Meier, W.
1976-01-01
The result of research work has shown that the eddy-current testing method can be used for austenetic steel up to 10 mm thick to detect cracks in the material. An exception to this are laminations if they are parallel to the surface. Cracks in the various geometrical positions in the test specimen produce different results in the x-y plot. They are influenced by the direction of the material cracks. Research into the influence the geometric parameters have on the indications shows that the eddy-current method provides clearer interpretations of material cracks than any other non-destructive test method known. (orig.) [de
Development of Eddy Current Technique for Reactor In-Core Flux Thimble Wear
International Nuclear Information System (INIS)
Park, S. S.; Jang, Y. Y.; Yim, C. Y.; Park, K. H.
1990-01-01
Since in-core flux thimble tube wear the due to flow-induced vibration could degrade the integrity of nuclear reactor, the effective detection and interpretation of the wear is important. In order to establish an inspection technique for thimble tubes, an eddy current experiment was performed to determine the optimum test frequency, defect sensitivity and evaluation accuracy. Eddy current probes were designed and fabricated with a theory. Specimens with artificial defects were fabricated using electro discharge machining method. The results from inspection technique developed and on-site inspection showed good applicability
Crack detection with an eddy-current probe integrated into an endoscope
International Nuclear Information System (INIS)
Elfinger, F.X.
1982-01-01
Objective and quantitive crack detection in inaccessible machine internals is possible without dismantling the equipment through the combination of endoscopic and eddy-current techniques, whereby the endoscope is used both as an optical and a mechanical manipulator. Thus the availability of machinery can be increased and the overhaul costs lowered. The integrated endoscope/eddy-current probe should be utilised whenever normal endoscopic inspection indicates a possible crack location which cannot be assessed definitively through visual observation alone. Its use is also advantageous in monitoring crack propagation within a component. (orig.) [de
Surface and near surface defect detection in thick copper EB-welds using eddy current testing
International Nuclear Information System (INIS)
Pitkaenen, J.; Lipponen, A.
2010-01-01
The surface inspection of thick copper electron beam (EB) welds plays an important role in the acceptance of nuclear fuel disposal. The main reasons to inspect these components are related to potential manufacturing and handling defects. In this work the data acquisition software, visualising tools for eddy current (EC) measurements and eddy current sensors were developed for detection of unwanted defects. The eddy current equipment was manufactured by IZFP and the visualising software in active co-operation with Posiva and IZFP for the inspections. The inspection procedure was produced during the development of the inspection techniques. The inspection method development aims to qualify the method for surface and near surface defect detection and sizing according to ENIQ. The study includes technical justification to be carried out, and compilation of a defect catalogue and experience from measurements within the Posiva's research on issues related to manufacturing. The depth of penetration in copper components in eddy current testing is rather small. To detect surface breaking defects the eddy current inspection is a good solution. A simple approach was adopted using two techniques: higher frequency was used to detect surface defects and to determine the dimensions of the defects except depth, lower frequency was used to detect defects having a ligament and for sizing of deeper surface breaking defects. The higher frequency was 30 kHz and the lower frequency was 200 Hz. The higher frequency probes were absolute bobbing coils and lower frequency probes combined transmitter - several receiver coils. To evaluate both methods, calibration blocks were manufactured by FNS for weld inspections. These calibration specimens mainly consisted of electron discharge machined notches and holes of varying shapes, lengths and diameters in the range of 1 mm to 20 mm of depth. Also one copper lid specimen with 152 defects was manufactured and used for evaluation of weld inspection
Signal Characteristics of Eddy Current Test for Intergranular Attack of Steam Generator Tubes
International Nuclear Information System (INIS)
Choi, Myung Sik; Lee, Deok Hyun; Han, Jung Ho; Hur, Do Haeng; Cho, Se Gon; Yim, Chang Jae
2002-01-01
Because intergranular attack (IGA), one of the localized corrosion forms occurring on steam generator tubes, can not be fabricated by an electric discharge machining method, there are few data for the eddy current test (ECT) characteristics of IGA. In this paper, the characteristics of eddy current signals are evaluated using nonexpanded tubes with IGA defects formed in 0.1 M sodium tetrathionate solution at 40 .deg. C. The detectability and sizing accuracy of IGA were discussed in terms of the coil type and frequency of the ECT probes
The R and D of half-sine pulser for eddy-current septum magnet
International Nuclear Information System (INIS)
Fu Luxin; Han Qian; Kang Wen
2002-01-01
The SSRF requires high-amplitude half-sine pulse current (10kA) and relatively narrow pulse width (∼60μs) for its eddy-current septum magnets. Moreover the machine will need a very high level of performance from the pulsers, particularly in terms of pulse amplitude stability and regulating range. For the convenience of maintenance the pulsers will be installed in the power supply hall and cabled to their eddy-current septum magnets by RG220/U. The author presents the pulser design and R and D results
Filippov, A. V.; Tarasov, S. Yu.; Filippova, E. O.; Chazov, P. A.; Shamarin, N. N.; Podgornykh, O. A.
2016-11-01
Monitoring of the edge clamped workpiece deflection during milling has been carried our using acoustic emission, accelerometer and eddy current sensors. Such a monitoring is necessary in precision machining of vital parts used in air-space engineering where a majority of them made by milling. The applicability of the AE, accelerometers and eddy current sensors has been discussed together with the analysis of measurement errors. The appropriate sensor installation diagram has been proposed for measuring the workpiece elastic deflection exerted by the cutting force.
The R and D of half-sine pulser for eddy-current septum magnet
Fu Lu Xin; Kang Wen
2002-01-01
The SSRF requires high-amplitude half-sine pulse current (10kA) and relatively narrow pulse width (approx 60 mu s) for its eddy-current septum magnets. Moreover the machine will need a very high level of performance from the pulsers, particularly in terms of pulse amplitude stability and regulating range. For the convenience of maintenance the pulsers will be installed in the power supply hall and cabled to their eddy-current septum magnets by RG220/U. The author presents the pulser design and R and D results
Eddy current quality control of soldered current-carrying busbar splices of superconducting magnets
Kogan, L; Savary, F; Principe, R; Datskov, V; Rozenfel'd, E; Khudjakov, B
2015-01-01
The eddy current technique associated with a U-shaped transducer is studied for the quality control of soldered joints between superconducting busbars ('splices'). Two other quality control techniques, based on X-rays and direct measurement of the electrical resistance, are also studied for comparison. A comparative analysis of the advantages and disadvantages of these three methods in relation to the quality control of soldered superconducting busbar cables enclosed in copper shells is used for benchmarking. The results of inspections with the U-shaped eddy current transducer carried out on several sample joints presenting different types of soldering defects show the potential of this type of nondestructive (ND) quality control technique.
The use of eddy current testing for nuclear fuel rods cladding evaluation
International Nuclear Information System (INIS)
Silva Junior, Silverio F. da; Alencar, Donizete A.; Brito, Mucio Jose D. de
2007-01-01
Nuclear fuel rods cladding must be tested after their manufacture and during their operational life. This paper describes a study about the use of eddy current test method as a nondestructive tool for nuclear fuel rods cladding evaluation. The experiments were carried out using two different probes: an external probe and an internal probe. The main goal was to verify the sensitivity of the eddy current test system, to develop calibration and reference standards and to establish the main capabilities and limitations presented by this test method for this application. (author)
Liu, Guoxi; Zhang, Chunli; Chen, Weiqiu; Dong, Shuxiang
2013-07-01
An analytical model of resonant magnetoelectric (ME) coupling in magnetostrictive (MS)-piezoelectric (PE) laminated composites in consideration of eddy-current effect in MS layer using equivalent circuit method is presented. Numerical calculations show that: (1) the eddy-current has a strong effect on ME coupling in MS-PE laminated composites at resonant frequency; and (2) the resonant ME coupling is then significantly dependent on the sizes of ME laminated composites, which were neglected in most previous theoretical analyses. The achieved results provide a theoretical guidance for the practice engineering design, manufacture, and application of ME laminated composites and devices.
Nondestructive evaluation of a cermet coating using ultrasonic and eddy current techniques
International Nuclear Information System (INIS)
Roge, B.; Fahr, A.; Giguere, J.S.R.; McRae, K.I.
2002-01-01
This paper describes a series of experiments conducted to characterize cermet coatings using conventional ultrasonic and eddy current techniques as well as an ultrasonic leaky surface wave method. The results demonstrate the ability of these techniques to detect the presence of artificial defects on the surface or beneath the surface of the coating. In addition, ultrasonic tests in particular ultrasonic leaky surface waves demonstrate the ability to detect the presence of manufacturing flaws. Ultrasonic time-of-flight and eddy current quadrature measurements also show sensitivity to variations in coating thickness
Subminiature eddy-current transducers designed to study welded joints of titanium alloys
Malikov, V. N.; Dmitriev, S. F.; Katasonov, A. O.; Sagalakov, A. M.; Ishkov, A. V.
2017-12-01
Eddy current transducers (ECT) are used to construct a sensor for investigating titanium sheets connected by a welded joint. The paper provides key technical information about the eddy current transducer used and describes the procedure of measurements that makes it possible to control defects in welded joints of titanium alloys. It is capable of automatically changing the filtering cutoff frequency and operating frequency of the device. Experiments were conducted on welded VT1-0 titanium plates. The paper contains the results of these measurements. The dependence data facilitates the assessment of the quality of the welded joints and helps make an educated conclusion about welding quality.
A domain derivative-based method for solving elastodynamic inverse obstacle scattering problems
International Nuclear Information System (INIS)
Le Louër, Frédérique
2015-01-01
The present work is concerned with the shape reconstruction problem of isotropic elastic inclusions from far-field data obtained by the scattering of a finite number of time-harmonic incident plane waves. This paper aims at completing the theoretical framework which is necessary for the application of geometric optimization tools to the inverse transmission problem in elastodynamics. The forward problem is reduced to systems of boundary integral equations following the direct and indirect methods initially developed for solving acoustic transmission problems. We establish the Fréchet differentiability of the boundary to far-field operator and give a characterization of the first Fréchet derivative and its adjoint operator. Using these results we propose an inverse scattering algorithm based on the iteratively regularized Gauß–Newton method and show numerical experiments in the special case of star-shaped obstacles. (paper)
2016-08-01
Science and Technology Organisation) EDM Electrodischarge machining FSH Full Screen Height on an eddy - current instrument IVD Ion Vapour...electromagnetic skin depth δ is 0.15 mm in the fastener holes3. 4.1 Bolt Hole Eddy Current Inspection Procedure 4.1.1 Calibration on Machined ...UNCLASSIFIED UNCLASSIFIED Discrimination between Fatigue Cracking and Mechanical Damage in Aircraft Fastener Holes by Eddy - Current Phase
An Adaptive Observer-Based Algorithm for Solving Inverse Source Problem for the Wave Equation
Asiri, Sharefa M.; Zayane, Chadia; Laleg-Kirati, Taous-Meriem
2015-01-01
Observers are well known in control theory. Originally designed to estimate the hidden states of dynamical systems given some measurements, the observers scope has been recently extended to the estimation of some unknowns, for systems governed by partial differential equations. In this paper, observers are used to solve inverse source problem for a one-dimensional wave equation. An adaptive observer is designed to estimate the state and source components for a fully discretized system. The effectiveness of the algorithm is emphasized in noise-free and noisy cases and an insight on the impact of measurements’ size and location is provided.
An Adaptive Observer-Based Algorithm for Solving Inverse Source Problem for the Wave Equation
Asiri, Sharefa M.
2015-08-31
Observers are well known in control theory. Originally designed to estimate the hidden states of dynamical systems given some measurements, the observers scope has been recently extended to the estimation of some unknowns, for systems governed by partial differential equations. In this paper, observers are used to solve inverse source problem for a one-dimensional wave equation. An adaptive observer is designed to estimate the state and source components for a fully discretized system. The effectiveness of the algorithm is emphasized in noise-free and noisy cases and an insight on the impact of measurements’ size and location is provided.
Determination of external measurements in aim to solve inverse heat conduction problem in piping
International Nuclear Information System (INIS)
Blanc, G.; Raynaud, M.; Chau, T.H.
1995-01-01
The inverse heat conduction problem (IHCP) to be solved involves with the reconstruction of unknown thermal loadings applied on piping internal wall. Only external temperature measurements are available as data. Different approaches can be found in the literature for solving this ill-posed problem. The most frequently used among them is the function specification method proposed by Professor BECK. However, for multidimensional IHCP, the accuracy of the solution strongly depends on the number of sensors and their location. This work focuses on the determination of minimal number and locations of the external thermocouples to get the most complete estimation of internal heat flux in a straight pipe. It more particularly concerns the preparation of experimental validation tests which will be performed on the ESTHER mock-up of Electricite de France (EDF). (authors). 4 refs., 9 figs
International Nuclear Information System (INIS)
Lim, T.
2011-01-01
To simulate numerically a non-destructive by eddy current testing (NDT-CF), the sensor response can be modeled through a semi-analytical approach by volume integral equations. Faster than the finite element method, this approach is however restricted to the study of plane or cylindrical parts (without taking into account the edge effects) because of the complexity of the expression of the dyadic Green function for more general configurations. However, there is an industrial demand to extend the capabilities of the CF model in complex configurations (deformed plates, edges effects...). We were thus brought to formulate the electromagnetic problem differently, by setting ourselves the goal of maintaining a semi-analytical approach. The surface integral equation (SIE) expresses the volume problem by an equivalent transmission one at the interfaces (2D) between homogeneous sub-domains. This problem is approached by a linear system (by the method of moments), whose number of unknowns is reduced due to the nature of the surfacic mesh. Therefore, this system can be solved by a direct solver for small configurations. That enabled us to treat several various positions of the sensor for only one inversion of the impedance matrix. The numerical results obtained using this formulation involve plates with consideration of edge effects such as edge and corner. They are consistent with results obtained by the finite element method. For larger configurations, we conducted a preliminary study for the adaptation of an acceleration method of the matrix vector product involved in an iterative solver (fast multipole method or FMM) to define the conditions under which the FMM calculation works correctly (accuracy, convergence...) in the NDT's domain. A special attention has been given to the choice of basis functions (which have to satisfy an Hdiv conforming property) and on the evaluation of near interactions (which are weakly singular). (author) [fr
International Nuclear Information System (INIS)
Endo, Takashi; Kamimura, Takeo; Nishihara, Masatoshi; Araki, Yasuo; Fukui, Shigetaka.
1982-05-01
Eddy current flaw detection techniques are applied to the in-service inspection (ISI) of steam generator tubes in pressurized water reactors (PWR) plant. To improve the reliability and operating efficiency of the plants, efforts are being made to develop eddy current testing methods of various kinds. Multi-frequency eddy current testing method, one of new method, has recently been applied to actual heat exchanger tubes, contributing to the improvement of the detectability and signal evaluation of the ISI. The outline of multi-frequency eddy current testing method and its effects on the improvement of flaw detecting and signal evaluation accuracy are described. (author)
Non destructive analysis apparatus by eddy currents for non magnetic metallic products
International Nuclear Information System (INIS)
Coutanceau-Monteil, N.; Billy, F.; Bernard, A.
1993-01-01
The device for non destructive testing of nonmagnetic metallic surfaces uses eddy currents with two independent receptors at different positions around the emitting coil which is fed with current impulses and whose axis is parallel to the surface under study. 4 figs
Measurement by eddy currents of tube-antivibratory bar gap steam generators of PWR power plants
International Nuclear Information System (INIS)
Savin, E.; Bieth, M.; Floze, J.C.
1990-01-01
In steam generators tubes are maintained by AVB to limit vibrations amplitude induced by secondary fluid flow. After some years wear sometimes occurs. For gap measurement between tubes and AVB Framatome developed a method based on eddy current and using a probe rotating inside the tube [fr
International Nuclear Information System (INIS)
Naegele, W.
1982-01-01
The usual formulation of multi-frequency eddy current signals of large defects by linearized impedance diagrams may lead to misinterpretations. Here a developement of the linear superposition principle is proposed, which takes into account also the curvature of the impedance diagrams thus allowing to identify even large defects in an unambiguous way. (orig.) [de
Eddy current testing device for metallic tubes at least locally curved
International Nuclear Information System (INIS)
Pigeon, Marcel; Vienot, Claude.
1975-01-01
Steam generators, condensers and heat exchangers generally consist of metallic tube bundles, the tubes having a complex geometry. The invention concerns an Eddy current testing device for metallic tubes at least locally curved, operating by translation of a probe inside the tubes [fr
The control of stainless steel tubes and wires of small diameter by the Eddy current method
International Nuclear Information System (INIS)
Stossel, A.; Gallet, G.
1978-01-01
Stainless steel tubes and wires with an outer diameter greater than 1 mm were studied by Eddy currents. The sensor characteristics and the detection of defects in function of frequency are presented together with the results obtained in the detection of dimensional and metallurgical defects [fr
Automated eddy current signal processing: operation between declarative and procedural programming
International Nuclear Information System (INIS)
Zorgati, R.; Georgel, B.; Duvaut, P.; Doligez, T.; Garreau, D.
1993-09-01
In this paper we present the problem of cooperation between numerical and symbolical programming. This cooperation enables an efficient substitution of some human based decisions. This approach is applied to Eddy current testing of steam generator tubes. We illustrate our purpose with results obtained with the mock-up Extraction. (authors). 1 fig., 5 refs
Analyses and tests for the baking system of the RFX vacuum vessel by eddy currents
International Nuclear Information System (INIS)
Collarin, P.; Sonato, P.; Zaccaria, P.; Zollino, G.
1995-01-01
The electrical, thermal and mechanical analyses carried out for the design of a new baking system for RFX by eddy currents are presented. The results of an experimental test on RFX with low heating power are reported as well. They gave confidence in the numerical analyses so as the working conditions with the nominal heating power were computed. (orig.)
Development of eddy-current-free MR imaging system with 0.3-T permanent magnet
International Nuclear Information System (INIS)
Kuroda, M.; Takeuchi, H.; Nishimura, H.; Yanaka, S.; Takeshima, H.; Yoshino, H.; Miyamoto, T.; Sakurai, H.
1990-01-01
This paper reports on the eddy current induced by the magnetic gradient field which causes various problems associated with a permanent magnet, the permanent magnetic circuit with new pole pieces has been studied. The magnetic circuit was composed of a permanent magnet, a yoke, and pole pieces. The pole pieces were magnetically connected to the Nd-Fe-B permanent magnet. To study for eddy current, read-size magnetic circuits with pole pieces of various material, such as (a) steel, (b) divided steel, (c) toroidal-shaped silicon steel, and (d) composite material were assembled. The whole 0.3-T MR imaging system consists of only three units, Gantry with coach, MR unit, and operational console with image processor. We have evaluated the frequency characteristics, rise time, spatial homogeneity of magnetic field, and image quality with respect to real-size magnetic circuits with various pole pieces. We have obtained following order for frequency characteristics: (d), (c), (b), (a). We have also made an effort to adjust uniformity of magnetic field for magnetic circuits with toroidal-shaped silicon steel. We have obtained crisp and accurate images with use of the new pole pieces, without causing an eddy current. Especially, MR angio imaging, which is sensitive for eddy current, can be obtained with remarkable improvement
International Nuclear Information System (INIS)
Georgel, B.; Zorgati, R.
1992-01-01
Improving speed and quality of Eddy Current non-destructive testing of steam generator tubes leads to automation of all process that contribute to diagnosis. This paper describes how signal processing, pattern recognition and artificial and artificial intelligence are used to build a software package that is able to automatically provide an efficient diagnosis. (author)
Analyses and tests for the baking system of the RFX vacuum vessel by eddy currents
Energy Technology Data Exchange (ETDEWEB)
Collarin, P. [Gruppo di Padova per Ricerche sulla Fusione, Univ. di Padova (Italy); Sonato, P. [Gruppo di Padova per Ricerche sulla Fusione, Univ. di Padova (Italy); Zaccaria, P. [Gruppo di Padova per Ricerche sulla Fusione, Univ. di Padova (Italy); Zollino, G. [Gruppo di Padova per Ricerche sulla Fusione, Univ. di Padova (Italy)
1995-12-31
The electrical, thermal and mechanical analyses carried out for the design of a new baking system for RFX by eddy currents are presented. The results of an experimental test on RFX with low heating power are reported as well. They gave confidence in the numerical analyses so as the working conditions with the nominal heating power were computed. (orig.).
DEFF Research Database (Denmark)
Egorov, Alexander; Kucheryavskiy, Sergey V.; Polyakov, Viktor
2017-01-01
The effect of eddy currents is widely used for diagnostics of conductive materials. It allows to create very simple and inexpensive systems for non-destructive measurements. However, the results of the measurements depend on many factors, including first of all, a conductivity of material...
EDDYTRAN program system for eddy current, electromagnetic force and structural analysis
International Nuclear Information System (INIS)
Kameari, A.; Nikura, S.
1983-01-01
A computer program system (EDDYTRAN), which is applicable to torus structures of magnetic fusion devices, has been developed to calculate the eddy current, electromagnetic force and structural analysis. The program system is designed to perform the following functions sequentially: 1) generation of model mesh and other data such as electromagnetic and mechanical properties of finite elements and boundary conditions, 2) calculations of eddy currents and electromagnetic forces, 3) transformation of the resultant force to load data fit to the structural analysis program, 4) structural analysis and 5) post-processing of the results. The EDDYTRAN utilizes the EDDYCUFF (EDDY CUrrent, magnetic Field and electromagnetic Force) program and the NASTRAN (NASA STRuctural ANalysis) program. Here, the EDDYCUFF program which has been developed by the authors is a generalized computer program to calculate transient eddy currents, resultant magnetic fields and electromagnetic forces in the conductive components. This paper describes the outline of the EDDYTRAN program system and preliminary results obtained through the application to the Tokamak reactor design which was performed for the Japan Atomic Energy Research Institute
Advances based on digital technology named TEDDY+ for inspection of eddy current
International Nuclear Information System (INIS)
Barcenilla, V.; Hernandez, J.; Ribes, B.
2007-01-01
As a result of the recent developing line of eddy current data acquisition system a new product based on digital technology named TEDDY+, comes to the market. With only 4 kg of weight constitutes a great advance with regards to other equipment's available in the market. These advances, have enabled, among others, to increase considerably the signal to noise (S/N) ratio, avoid typical saturation problems in the eddy current signal, increase the inspection speed, eliminate the reference probe, detect the air/tube signal in real time, and the possibility to integrate the tester inside a push puller thanks to its reduced size and to have integrated as part of the ET equipment the mechanical systems control board. Two product lines have been developed, one oriented to any market and application (nuclear market, industrial and aeronautical, chemical and petrochemical, etc) and other specially dedicated to the massive inspection of tubes, named TEDDY+SP (Suitcase Pusher). Both lines are prepared to use eddy current arrays which clearly constitute the future of the eddy current inspection systems. The new TEDDY+ line of products presented in this paper constitutes one of the most powerful and reliable existing in the market. These improvements and novelties place the new ET inspection system from Tecnatom as one of the most powerful and reliable in the market. (Author)
NDE reliability gains from combining eddy-current and ultrasonic testing
International Nuclear Information System (INIS)
Horn, D.; Mayo, W.R.
1999-01-01
We investigate statistical methods for combining the results of two complementary inspection techniques, eddy-current and ultrasonic testing. The reliability of rejection/acceptance decisions based on combined information is compared with that based on each inspection technique individually. The measured reliability increases with the amount of information incorporated in the decision. (author)
Adaptation of eddy current methods to the multiple problems of reactor testing
International Nuclear Information System (INIS)
Stumm, W.
1975-01-01
In reactor testing, the eddy current method is mainly used for the testing of surface regions inside the pressure vessel, on welds and joints, and for the testing of thin-walled pipes, e.g. the heat exchanger pipes. (RW/AK) [de
Design and Application of Hybrid Magnetic Field-Eddy Current Probe
Wincheski, Buzz; Wallace, Terryl; Newman, Andy; Leser, Paul; Simpson, John
2013-01-01
The incorporation of magnetic field sensors into eddy current probes can result in novel probe designs with unique performance characteristics. One such example is a recently developed electromagnetic probe consisting of a two-channel magnetoresistive sensor with an embedded single-strand eddy current inducer. Magnetic flux leakage maps of ferrous materials are generated from the DC sensor response while high-resolution eddy current imaging is simultaneously performed at frequencies up to 5 megahertz. In this work the design and optimization of this probe will be presented, along with an application toward analysis of sensory materials with embedded ferromagnetic shape-memory alloy (FSMA) particles. The sensory material is designed to produce a paramagnetic to ferromagnetic transition in the FSMA particles under strain. Mapping of the stray magnetic field and eddy current response of the sample with the hybrid probe can thereby image locations in the structure which have experienced an overstrain condition. Numerical modeling of the probe response is performed with good agreement with experimental results.
International Nuclear Information System (INIS)
Georgel, B.; Zorgati, R.
1994-01-01
Improving speed and quality of Eddy Current non-destructive testing of steam generator tubes leads to automatize all processes that contribute to diagnosis. This paper describes how we use signal processing, pattern recognition and artificial intelligence to build a software package that is able to automatically provide an efficient diagnosis. (authors). 2 figs., 5 refs
Eddy current detection of spacers in the fuel channels of CANDU nuclear reactors
International Nuclear Information System (INIS)
Krause, T.W.; Schankula, J.; Sullivan, S.P.
2002-01-01
Garter Spring (GS) spacers in the fuel channels of CANDU nuclear reactors maintain separation between the hot pressure tube and surrounding moderator cooled calandria tube. Eddy current detection of the four GSs provides assurance that spacers are at or close to design positions and are performing their intended function of maintaining a non-zero gap between pressure tube and calandria tube. Pressure tube constrictions, resulting from relatively less diametral creep at end-of-fuel bundle locations, also produce large eddy current signals. Large constrictions, present in higher service pressure tubes, can produce signals that are 10 times larger than GS signals, reducing GS detectability to 30% in standard GS-detect probes. The introduction of field-focussing elements into the design of the standard GS detection eddy current probe has been used to recover the detectability of GS spacers by increasing the signal amplitude obtained from GSs relative to that from constrictions by a factor of 10. The work presented here compares laboratory, modelling and in-reactor measurements of GS and constriction signals obtained from the standard probe with that obtained from field-focussed eddy current probe designs. (author)
Eddy Current, Magnetic Particle and Hardness Testing, Aviation Quality Control (Advanced): 9227.04.
Dade County Public Schools, Miami, FL.
This unit of instruction includes the principles of eddy current, magnetic particle and hardness testing; standards used for analyzing test results; techniques of operating equipment; interpretation of indications; advantages and limitations of these methods of testing; care and calibration of equipment; and safety and work precautions. Motion…
A method for crack profiles identification in eddy current testing by the multi-directional scan
International Nuclear Information System (INIS)
Kojima, Fumio; Ikeda, Takuya; Nguyen, Doung
2006-01-01
This paper is concerned with a method for identification of crack shape in conducting materials. Multi-directional scanning strategies using Eddy Current Testing is performed for sizing complex natural crackings. Two dimensional measurements by means of multi-directional scan are used in a output least square identifications. (author)
Investigation of steel to dielectric transition using microminiature eddy-current converter
Directory of Open Access Journals (Sweden)
Malikov Vladimir
2018-01-01
Full Text Available The research aims to develop a microminiature converter for electrical steel investigation. The research topic is considered relevant due to the need for evaluation and forecasting of safe operating life of electric steel products. The authors determined the capability to study steel characteristics at different depths based on variations of eddy-current converter amplitude at the steel-dielectric boundary. A microminiature transformer-type converter was designed, which enables to perform local investigations of ferromagnetic materials using eddy-current method based on local studies of the steel electrical conductivity. Having the designed converter as a basis, a hardware-software complex was built to perform experimental studies of steel at the interface boundary. A system was developed for automated converter relocation above the studied object at a specified velocity. Test results are reported for a specimen with continuous and discrete measurements taken at different frequencies. Response dependence of eddy-current converter was found to demonstrate non-linear behavior at steel to dielectric transition. The effect of gap between the eddy-current converter and the test object is investigated.
Influence of residual stresses during eddy current testing of zircaloy bar material
International Nuclear Information System (INIS)
Saibaba, N.; Das, G.; Pratap, Y.; Acharya, S.; Chaube, R.K.; Jayaraj, R.N.
2009-01-01
Full text: Zirconium alloy bar is the input material for making end plugs required for encapsulating the fuel tubes after loading of uranium di-oxide pellets. These bars are manufactured through extrusion followed by multi-pass swaging and intermediate vacuum annealing. The bar is subjected to 100% Ultrasonic testing to ensure that defect free material is used for making the end plugs. The elements thus welded are subjected to helium leak testing for checking the weld integrity. However, stray cases of helium leakage from fuel elements were observed on few occasions. On investigation, it was found that the leakage was from small porosity present in the plugs. In order to isolate such an eventuality, stricter ultrasonic standards were adopted and additionally eddy current testing was introduced. It was observed that a number of eddy current signals equal to the defect standard were noticed and the reasons for these indications could not be identified. This led to a significant fall in the material recovery. An in-depth study with various heat treatment cycles and process steps was carried out. It was finally concluded that the indications observed in eddy current testing were due to the residual stresses on the periphery of the bar material caused due by improper straightening being carried out at the final stage of the bar manufacture. This paper presents the systematic studies carried out and correlation established between the eddy current signals and the residual stresses
Eddy Current Loss Modeling for Design of PM Generators for Wind Turbines
Jassal, A.
2014-01-01
This thesis deals with analysis, calculation and validation of eddy current loss models for Permanent Magnet (PM) direct drive generators for wind turbines. The modelling approach is a mixed use of analytical and Finite Element (FE) methods. The models are validated experimentally and design
Considerations on heat deposition by eddy currents in the cold structure of INTOR/NET
International Nuclear Information System (INIS)
Bloemer, B.; Farfaletti-Casali, F.
1983-01-01
In a tokamak like INTOR/NET large eddy currents can be induced in all conductive parts of the reactor mainly by the time-varying poloidal fields. In order to minimize the refrigeration power the heat load generated by eddy currents has to be kept as small as possibly especially in the large toroidal- and poloidal-field coil support structures, which are conductive and at temperatures of less than 4.2 K. A method is described identifying the parts of the structure wherein most of the heat generated by eddy currents is dissipated. By dividing a given configuration into reasonable segments of appointed geometry eddy current losses can easily be calculated. Compared to sophisticated computer programs this procedure is simple but of sufficient accuracy for a lot of applications and it delivers prompt results. The method is applied to the TF coil support structure of a specific design of INTOR/NET. As the results show that the heat load is intolerably high a modified design is proposed. (author)
Claycomb, James Ronald
1998-10-01
Several High-T c Superconducting (HTS) eddy current probes have been developed for applications in electromagnetic nondestructive evaluation (NDE) of conducting materials. The probes utilize high-T c SUperconducting Quantum Interference Device (SQUID) magnetometers to detect the fields produced by the perturbation of induced eddy currents resulting from subsurface flaws. Localized HTS shields are incorporated to selectively screen out environmental electromagnetic interference and enable movement of the instrument in the Earth's magnetic field. High permeability magnetic shields are employed to focus flux into, and thereby increase the eddy current density in the metallic test samples. NDE test results are presented, in which machined flaws in aluminum alloy are detected by probes of different design. A novel current injection technique performing NDE of wires using SQUIDs is also discussed. The HTS and high permeability shields are designed based on analytical and numerical finite element method (FEM) calculations presented here. Superconducting and high permeability magnetic shields are modeled in uniform noise fields and in the presence of dipole fields characteristic of flaw signals. Several shield designs are characterized in terms of (1) their ability to screen out uniform background noise fields; (2) the resultant improvement in signal-to-noise ratio and (3) the extent to which dipole source fields are distorted. An analysis of eddy current induction is then presented for low frequency SQUID NDE. Analytical expressions are developed for the induced eddy currents and resulting magnetic fields produced by excitation sources above conducting plates of varying thickness. The expressions derived here are used to model the SQUID's response to material thinning. An analytical defect model is also developed, taking into account the attenuation of the defect field through the conducting material, as well as the current flow around the edges of the flaw. Time harmonic
Al-Ma'shumah, Fathimah; Permana, Dony; Sidarto, Kuntjoro Adji
2015-12-01
Customer Lifetime Value is an important and useful concept in marketing. One of its benefits is to help a company for budgeting marketing expenditure for customer acquisition and customer retention. Many mathematical models have been introduced to calculate CLV considering the customer retention/migration classification scheme. A fairly new class of these models which will be described in this paper uses Markov Chain Models (MCM). This class of models has the major advantage for its flexibility to be modified to several different cases/classification schemes. In this model, the probabilities of customer retention and acquisition play an important role. From Pfeifer and Carraway, 2000, the final formula of CLV obtained from MCM usually contains nonlinear form of the transition probability matrix. This nonlinearity makes the inverse problem of CLV difficult to solve. This paper aims to solve this inverse problem, yielding the approximate transition probabilities for the customers, by applying metaheuristic optimization algorithm developed by Yang, 2013, Flower Pollination Algorithm. The major interpretation of obtaining the transition probabilities are to set goals for marketing teams in keeping the relative frequencies of customer acquisition and customer retention.
Solving the inverse heat conduction problem using NVLink capable Power architecture
Directory of Open Access Journals (Sweden)
Sándor Szénási
2017-11-01
Full Text Available The accurate knowledge of Heat Transfer Coefficients is essential for the design of precise heat transfer operations. The determination of these values requires Inverse Heat Transfer Calculations, which are usually based on heuristic optimisation techniques, like Genetic Algorithms or Particle Swarm Optimisation. The main bottleneck of these heuristics is the high computational demand of the cost function calculation, which is usually based on heat transfer simulations producing the thermal history of the workpiece at given locations. This Direct Heat Transfer Calculation is a well parallelisable process, making it feasible to implement an efficient GPU kernel for this purpose. This paper presents a novel step forward: based on the special requirements of the heuristics solving the inverse problem (executing hundreds of simulations in a parallel fashion at the end of each iteration, it is possible to gain a higher level of parallelism using multiple graphics accelerators. The results show that this implementation (running on 4 GPUs is about 120 times faster than a traditional CPU implementation using 20 cores. The latest developments of the GPU-based High Power Computations area were also analysed, like the new NVLink connection between the host and the devices, which tries to solve the long time existing data transfer handicap of GPU programming.
A Hybrid Optimization Method for Solving Bayesian Inverse Problems under Uncertainty.
Directory of Open Access Journals (Sweden)
Kai Zhang
Full Text Available In this paper, we investigate the application of a new method, the Finite Difference and Stochastic Gradient (Hybrid method, for history matching in reservoir models. History matching is one of the processes of solving an inverse problem by calibrating reservoir models to dynamic behaviour of the reservoir in which an objective function is formulated based on a Bayesian approach for optimization. The goal of history matching is to identify the minimum value of an objective function that expresses the misfit between the predicted and measured data of a reservoir. To address the optimization problem, we present a novel application using a combination of the stochastic gradient and finite difference methods for solving inverse problems. The optimization is constrained by a linear equation that contains the reservoir parameters. We reformulate the reservoir model's parameters and dynamic data by operating the objective function, the approximate gradient of which can guarantee convergence. At each iteration step, we obtain the relatively 'important' elements of the gradient, which are subsequently substituted by the values from the Finite Difference method through comparing the magnitude of the components of the stochastic gradient, which forms a new gradient, and we subsequently iterate with the new gradient. Through the application of the Hybrid method, we efficiently and accurately optimize the objective function. We present a number numerical simulations in this paper that show that the method is accurate and computationally efficient.
Solution of magnetic field and eddy current problem induced by rotating magnetic poles (abstract)
Liu, Z. J.; Low, T. S.
1996-04-01
The magnetic field and eddy current problems induced by rotating permanent magnet poles occur in electromagnetic dampers, magnetic couplings, and many other devices. Whereas numerical techniques, for example, finite element methods can be exploited to study various features of these problems, such as heat generation and drag torque development, etc., the analytical solution is always of interest to the designers since it helps them to gain the insight into the interdependence of the parameters involved and provides an efficient tool for designing. Some of the previous work showed that the solution of the eddy current problem due to the linearly moving magnet poles can give satisfactory approximation for the eddy current problem due to rotating fields. However, in many practical cases, especially when the number of magnet poles is small, there is significant effect of flux focusing due to the geometry. The above approximation can therefore lead to marked errors in the theoretical predictions of the device performance. Bernot et al. recently described an analytical solution in a polar coordinate system where the radial field is excited by a time-varying source. A discussion of an analytical solution of the magnetic field and eddy current problems induced by moving magnet poles in radial field machines will be given in this article. The theoretical predictions obtained from this method is compared with the results obtained from finite element calculations. The validity of the method is also checked by the comparison of the theoretical predictions and the measurements from a test machine. It is shown that the introduced solution leads to a significant improvement in the air gap field prediction as compared with the results obtained from the analytical solution that models the eddy current problems induced by linearly moving magnet poles.
Evaluation of the eddy-current method of inspecting steam generator tubing
International Nuclear Information System (INIS)
Flora, J.H.; Brown, S.D.; Weeks, J.R.
1976-01-01
The objective of this project has been to evaluate the eddy-current method of inspecting steam generator tubing by conducting a series of laboratory experiments with conventional eddy-current equipment. The experiments have involved obtaining eddy-current measurements on samples of 7/8-inch OD Inconel-600 tubing provided by the Westinghouse Nuclear Energy Systems Division. A variety of machined defects and some chemically induced flaws, such as stress corrosion cracks were fabricated in the tubing. Statistical evaluation of the data was employed to estimate the error encountered in measuring corrosion defects of various depths. It appears that the eddy-current technique can provide a reasonable measure of defect depth under certain conditions. On the other hand, the evaluation indicates that it is difficult to determine the depth of certain types of flaws with reliability and precision. Furthermore, although some defects as shallow as 10 percent of the tube wall could be detected, it was not possible to detect other types of flaws that were less than 40 percent deep even when the tube supports were not near the defects. The difficulty in detecting small volume flaws is attributed to low signal-to-noise ratio. Noise is a result of unwanted signals from test variables, such as wobble and variations in tube properties. The error in measurement of certain types of larger defects is associatedin part with test variables and also with the effects that the geometry of the defect has on the eddy-current signal patterns. The distortions in signal patterns caused by gradual wastage type defects and the poor reproducibility of signal patterns obtained from notches that represent stress corrosion cracks are described. Some developments that will rectify these detection and depth measurement problems are discussed
Evaluation of the eddy-current method for the inspection of steam generator tubing: denting
International Nuclear Information System (INIS)
Brown, S.D.; Flora, J.H.
1977-01-01
Continued evaluation of existing eddy-current in-service inspection (ISI) methods for steam generator tubing has emphasized the effects of denting. Denting is a circumferential deformation of the tube in the support region as a result of the formation of a magnetite, Fe 3 O 4 , corrosion product on the carbon steel tube support plate in the crevice between the support plate and the tube wall. The effects of denting on eddy current inspection are twofold: (1) The detection and measurement of defects in the dented region is hampered by the distortion of the eddy-current response signals caused by the dents and (2) large dents may prevent the passage of high fill factor probes forcing the inspection teams to use a smaller probe in undented regions. Unless appropriate measures are taken, less reliable detection of defects and estimation of their depth can result. The report presents an experimental evaluation of existing eddy-current ISI methods when used to inspect dented regions. Tubes were mechanically dented to simulate various degrees of service induced denting. These tubes were then inserted in carbon steel tube support plates and the crevice region between the support plate and tube was subsequently packed with powdered magnetite. Diametral dent sizes considered during this program varied between 1 and 10 mils. Eddy-current signal patterns and strip chart recordings were obtained using a variety of test parameters, such as frequency, phase rotation and coil configuration, on tube samples containing various degrees of denting and with several types of defects in the dented system
International Nuclear Information System (INIS)
Nagaya, Yoshiaki; Endo, Hisashi; Takagi, Toshiyuki; Uchimoto, Tetsuya
2005-01-01
This paper deals with identifying multiple cracks from eddy current testing (ECT) signals obtained in a steam generator tube with a support plate and deposits. Assume two-dimensionally scanned ECT signals to be a picture image, then the signal processing by a multi-frequency technique eliminates noise caused by the support plate and deposits. A template matching with help of genetic algorithms detects number and positions of cracks from the image after the signal processing. Inverse analysis estimates the crack profile based on the predicted position of cracks. The number and positions of the cracks are sufficiently well predicted. Crack shape reconstructions are achieved with a satisfactory degree of accuracy. (author)
Directory of Open Access Journals (Sweden)
Zhang Lei
2015-01-01
Full Text Available The paper gives detailed systematic researches on the mechanism and key factors of eddy-current losses in rotor magnets of high power-density permanent magnet synchronous motors(PMSMs. Firstly, this paper establishes quantitative mathematic model of eddy-current losses for surface-mounted PMSM based on eddy current field model and Maxwell equations. Then, a scaling index is put forward to weigh the key factors relevant to the eddy-current losses in magnets. At the same time, the principles of eddy-current losses in prototype PMSM are analyzed by the finite element analysis (FEA software. The contents researched in the paper have practical reference values for design and reliability analysis of PMSMs.
International Nuclear Information System (INIS)
Abe, Mitsushi; Takeuchi, Kazuhiro; Fukumoto, Hideshi; Otsuka, Michio
1989-01-01
A magnetic analysis to determine plasma surface position is applied to the magnetic data of the Hitachi Tokamak (HT-2). The analysis takes account of toroidal eddy currents on the vacuum vessel wall. Magnetic probes in HT-2 are placed on both sides of the wall (plasma side and outside), making it possible to determine magnitudes of eddy currents which flow in the toroidal direction. The magnitudes of the coil currents and eddy currents are determined so as to reproduce the measured magnetic fields, and to reconstruct flux surfaces and plasma surface are reconstructed. Taking into account the eddy currents, the determination errors of the plasma surface position are reduced by up to 1/2.3 during start-up and terminating phases, compared with the case without eddy currents. (author)
Application of Discrete Fourier Transform in solving the inverse problem in gamma-ray logging
International Nuclear Information System (INIS)
Zorski, T.
1980-01-01
A new approach to the solution of inverse problem in gamma-ray logging is presented. The equation: I(z) = ∫sup(+infinite)sub(-infinite) phi (z-z')Isub(infinite)(z')dz', which relates the measured intensity I(z) with the intensity Isub(infinite)(z) not disturbed by finite thickness of an elementary layer, is solved for Isub(infinite)(z). Discrete Fourier Transform and convolution theorem are used. As a result of our solution discrete values of Isub(infinite)(z) given at a step of Δh are obtained. Examples of application of this method for Δh <= 4.5 cm and for the curves I(z) theoretically calculated are also discussed. (author)
Inexact Newton–Landweber iteration for solving nonlinear inverse problems in Banach spaces
International Nuclear Information System (INIS)
Jin, Qinian
2012-01-01
By making use of duality mappings, we formulate an inexact Newton–Landweber iteration method for solving nonlinear inverse problems in Banach spaces. The method consists of two components: an outer Newton iteration and an inner scheme providing the increments by applying the Landweber iteration in Banach spaces to the local linearized equations. It has the advantage of reducing computational work by computing more cheap steps in each inner scheme. We first prove a convergence result for the exact data case. When the data are given approximately, we terminate the method by a discrepancy principle and obtain a weak convergence result. Finally, we test the method by reporting some numerical simulations concerning the sparsity recovery and the noisy data containing outliers. (paper)
Zhang, Ye; Gong, Rongfang; Cheng, Xiaoliang; Gulliksson, Mårten
2018-06-01
This study considers the inverse source problem for elliptic partial differential equations with both Dirichlet and Neumann boundary data. The unknown source term is to be determined by additional boundary conditions. Unlike the existing methods found in the literature, which usually employ the first-order in time gradient-like system (such as the steepest descent methods) for numerically solving the regularized optimization problem with a fixed regularization parameter, we propose a novel method with a second-order in time dissipative gradient-like system and a dynamical selected regularization parameter. A damped symplectic scheme is proposed for the numerical solution. Theoretical analysis is given for both the continuous model and the numerical algorithm. Several numerical examples are provided to show the robustness of the proposed algorithm.
Abdelsalhin, Tiziano; Maselli, Andrea; Ferrari, Valeria
2018-04-01
The LIGO/Virgo Collaboration has recently announced the direct detection of gravitational waves emitted in the coalescence of a neutron star binary. This discovery allows, for the first time, to set new constraints on the behavior of matter at supranuclear density, complementary with those coming from astrophysical observations in the electromagnetic band. In this paper we demonstrate the feasibility of using gravitational signals to solve the relativistic inverse stellar problem, i.e., to reconstruct the parameters of the equation of state (EoS) from measurements of the stellar mass and tidal Love number. We perform Bayesian inference of mock data, based on different models of the star internal composition, modeled through piecewise polytropes. Our analysis shows that the detection of a small number of sources by a network of advanced interferometers would allow to put accurate bounds on the EoS parameters, and to perform a model selection among the realistic equations of state proposed in the literature.
A hopfield-like artificial neural network for solving inverse radiation transport problems
International Nuclear Information System (INIS)
Lee, Sang Hoon
1997-02-01
In this thesis, we solve inverse radiation transport problems by an Artificial Neural Network(ANN) approach. ANNs have many interesting properties such as nonlinear, parallel, and distributed processing. Some of the promising applications of ANNs are optimization, image and signal processing, system control, etc. In some optimization problems, Hopfield Neural Network(HNN) which has one-layered and fully interconnected neurons with feed-back topology showed that it worked well with acceptable fault tolerance and efficiency. The identification of radioactive source in a medium with a limited number of external detectors is treated as an inverse radiation transport problem in this work. This kind of inverse problem is usually ill-posed and severely under-determined; however, its applications are very useful in many fields including medical diagnosis and nondestructive assay of nuclear materials. Therefore, it is desired to develop efficient and robust solution algorithms. Firstly, we study a representative ANN model which has learning ability and fault tolerance, i.e., feed-forward neural network. It has an error backpropagation learning algorithm processed by reducing error in learning patterns that are usually results of test or calculation. Although it has enough fault tolerance and efficiency, a major obstacle is 'curse of dimensionality'--required number of learning patterns and learning time increase exponentially proportional to the problem size. Therefore, in this thesis, this type of ANN is used as benchmarking the reliability of the solution. Secondly, another approach for solving inverse problems, a modified version of HNN is proposed. When diagonal elements of the interconnection matrix are not zero, HNN may become unstable. However, most problems including this identification problem contain non-zero diagonal elements when programmed on neural networks. According to Soulie et al., discrete random iterations could produce the stable minimum state
Desmal, Abdulla
2014-07-01
A numerical framework that incorporates recently developed iterative shrinkage thresholding (IST) algorithms within the Born iterative method (BIM) is proposed for solving the two-dimensional inverse electromagnetic scattering problem. IST algorithms minimize a cost function weighted between measurement-data misfit and a zeroth/first-norm penalty term and therefore promote "sharpness" in the solution. Consequently, when applied to domains with sharp variations, discontinuities, or sparse content, the proposed framework is more efficient and accurate than the "classical" BIM that minimizes a cost function with a second-norm penalty term. Indeed, numerical results demonstrate the superiority of the IST-BIM over the classical BIM when they are applied to sparse domains: Permittivity and conductivity profiles recovered using the IST-BIM are sharper and more accurate and converge faster. © 1963-2012 IEEE.
Methods and Algorithms for Solving Inverse Problems for Fractional Advection-Dispersion Equations
Aldoghaither, Abeer
2015-11-12
observations. An analytic solution for the non-homogeneous case is derived and existence and uniqueness of the solution are established. In addition, the uniqueness and stability of the inverse problem is studied. Moreover, the modulating functions-based method is used to solve the problem and it is compared to a standard Tikhono-based optimization technique.
International Nuclear Information System (INIS)
Becker, R.
1980-01-01
Application of the multi-frequency method in eddy current testing is shown to be usefull for many important and complex problems in the field of non-destructive testing, which cannot be solved by the single frequency method because of principle reasons. Also in the presence of several perturbing signals the method can be applied successfully, thus very often difference coils can be replaced by absolute coils. Introducing the algorithm of multidimensional direction selection, the calibration of the test system is simpler, allowing automization of the calibration process. In addition, the test signals related with the defect parameters can be evaluated in an objective way. (orig./RW) [de
Use of Genetic Algorithms to solve Inverse Problems in Relativistic Hydrodynamics
Guzmán, F. S.; González, J. A.
2018-04-01
We present the use of Genetic Algorithms (GAs) as a strategy to solve inverse problems associated with models of relativistic hydrodynamics. The signal we consider to emulate an observation is the density of a relativistic gas, measured at a point where a shock is traveling. This shock is generated numerically out of a Riemann problem with mildly relativistic conditions. The inverse problem we propose is the prediction of the initial conditions of density, velocity and pressure of the Riemann problem that gave origin to that signal. For this we use the density, velocity and pressure of the gas at both sides of the discontinuity, as the six genes of an organism, initially with random values within a tolerance. We then prepare an initial population of N of these organisms and evolve them using methods based on GAs. In the end, the organism with the best fitness of each generation is compared to the signal and the process ends when the set of initial conditions of the organisms of a later generation fit the Signal within a tolerance.
Calculation and Analysis of Permanent Magnet Eddy Current Loss Fault with Magnet Segmentation
Directory of Open Access Journals (Sweden)
Bing Li
2016-01-01
Full Text Available This paper investigates the problem of calculating and analyzing the effect of the permanent magnet eddy current loss fault due to magnet segmentation. Taking an interior permanent magnet synchronous motor with inverter supplied as an example, the rated power of motor was 2.2 kW. Three-dimensional finite-element model was firstly established based on finite-element software. Then, the model mesh and boundary conditions were handled specially; permanent magnet eddy current loss fault was calculated and analyzed theoretically with magnet segmentation from space harmonic and time harmonic, respectively. Finally, calculation results were compared and explained. A useful conclusion for permanent magnet synchronous motor design has been obtained.
Coupling method of magnetic memory and eddy current nondestructive testing for retired crankshafts
Energy Technology Data Exchange (ETDEWEB)
Ni, Chen; Hua, Lin; Wang, Xiaokai; Wang, Zhou; Qin, Xunpeng; Fang, Zhou [Wuhan University of Technology, Wuhan (Korea, Republic of)
2016-07-15
To verify the validity of the Coupling method of magnetic memory and eddy current (CMMEC) testing for crankshafts, we use this technique to test a 12-cylinder V-design diesel crankshaft. First, the stress distribution in the crankshaft was obtained under 12 working conditions using a Finite element (FE) model that complied with the commercial FE code ABAQUS. Second, Magnetic memory testing (MMT) and Eddy current testing (ECT) were adopted to detect the regions of stress concentration in the crankshaft and the specific location of cracks based on simulation results. Lastly, magnetic particle testing was conducted to detect and display the corresponding crack to verify the CMMEC testing results. The MMT and ECT results can provide basis and guidance for the remanufacture and life evaluation of retired crankshafts.
Experimental measurements of the eddy current signal due to a flawed, conducting half space
International Nuclear Information System (INIS)
Long, S.A.; Toomsawasdi, S.; Zaman, A.J.M.
1984-01-01
This chapter reports on an experimental investigation in which the change in impedance of a practical multi-turn eddy current coil near a conducting half space is measured as a function of the conductivity and the lift-off distance. The results are compared in a qualitative fashion with the analytical results for a single-turn coil. Measurements are also made of the change in impedance due to a small void in the conducting half space as a function of both its depth and radial position. The results indicate that, at least in a qualitative fashion, the precisely derived analytical solutions adequately predict the general behavior of the change in complex impedance of an eddy current coil above a conducting ground plane as a function of lift-off distance. It is determined that the effect of a sub-surface void on the change in inductance of the test coil correlates well with theoretical calculations
International Nuclear Information System (INIS)
Taghvaei, A.H.; Shokrollahi, H.; Janghorban, K.; Abiri, H.
2009-01-01
This work investigates the magnetic properties of iron-phosphate-polyepoxy soft magnetic composite materials. FTIR spectra, EDX analysis, distribution maps, X-ray diffraction pattern and density measurements show that the particles surface layer contains a thin layer of nanocrystalline/amorphous phosphate with high coverage of powders surface. In this paper, a formula for calculating the eddy current loss and total loss components by loss separation method is presented and finally the different parts of power losses are calculated. The results show that, the contribution of eddy current in the bulk material for single coating layer (k b = 0.18) is higher in comparison with double coating layer (k b = 0.09). Moreover, iron-phosphate-polyepoxy composites (P = 0.000004f 2 ) have lower power loss in comparison with iron-phosphate composites (P = 0.00002f 2 ).
Design of a Shielded Reflection Type Pulsed Eddy Current Probe for the Evaluation of Thickness
Energy Technology Data Exchange (ETDEWEB)
Shin, Young Kil; Choi, Dong Myung [Kunsan National University, Gunsan (Korea, Republic of)
2007-10-15
For better evaluation of material thickness by using the reflection type pulsed eddy current method, various probe models are designed and their response signals, characteristics, and sensitivities to thickness variation are investigated by a numerical analysis method. Since the sensor needs to detect magnetic fields from eddy currents induced in a test material, not from the exciter coil, two types of models that are shielded by the combination of copper and ferrite and only by ferrite are considered. By studying response signals from these shielded probe models, the peak value and the zero crossing time are selected as useful signal features for the evaluation of material thickness. Investigation of sensitivities of these two features shows that the sensitivity of peak value is more useful than that of zero crossing time and that the probe shielded only by ferrite gives much better sensitivity to thickness variation
A Steel Ball Surface Quality Inspection Method Based on a Circumferential Eddy Current Array Sensor.
Zhang, Huayu; Xie, Fengqin; Cao, Maoyong; Zhong, Mingming
2017-07-01
To efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA) sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor), magnetic field intensity, and induced eddy current density on the surface of a sample steel ball, was determined using 3-, 4-, 5-, and 6-coil probes, for analysis and comparison. The optimal lift-off from the measured steel ball, the number of probe coils, and the frequency of excitation current suitable for steel ball inspection were obtained. Using the resulting CECA sensor to inspect 46,126 steel balls showed a miss rate of ~0.02%. The sensor was inspected for surface defects as small as 0.05 mm in width and 0.1 mm in depth.
Eddy current damping for magnetic levitation: downscaling from macro- to micro-levitation
International Nuclear Information System (INIS)
Elbuken, C; Khamesee, M B; Yavuz, M
2006-01-01
Magnetic levitation of miniaturized objects is investigated in this paper. A magnetic levitation setup is built to implement one-dimensional magnetic levitation motion. It was observed that as the levitated object becomes smaller, magnetic levitation suffers more from undesired vibrations. As a solution, eddy current damping is offered and implemented successfully by placing conductive plates close to the levitated object. An analytical expression for damping coefficient is derived. Experimentally, it is shown that eddy current damping can reduce the RMS positioning error to the level of more than one third of its original value for a 0.386 g object levitated in an air-gap region of 290 mm. The proposed system has the potential to be used for micro-manipulation purposes in a high motion range of 39.8 mm
Eddy current damping for magnetic levitation: downscaling from macro- to micro-levitation
Energy Technology Data Exchange (ETDEWEB)
Elbuken, C; Khamesee, M B; Yavuz, M [Department of Mechanical and Mechatronics Engineering, University of Waterloo, Ontario (Canada)
2006-09-21
Magnetic levitation of miniaturized objects is investigated in this paper. A magnetic levitation setup is built to implement one-dimensional magnetic levitation motion. It was observed that as the levitated object becomes smaller, magnetic levitation suffers more from undesired vibrations. As a solution, eddy current damping is offered and implemented successfully by placing conductive plates close to the levitated object. An analytical expression for damping coefficient is derived. Experimentally, it is shown that eddy current damping can reduce the RMS positioning error to the level of more than one third of its original value for a 0.386 g object levitated in an air-gap region of 290 mm. The proposed system has the potential to be used for micro-manipulation purposes in a high motion range of 39.8 mm.
International Nuclear Information System (INIS)
Nonaka, S.; Sakamoto, T.; Veno, T.
1987-01-01
The eddy currents on the cryostat outer-vessel of an SCM(superconducting magnet) are investigated taking into account of the non-contact on-board power generator system. Numerical expressions are developed by combining a Fourier series method and an integral equation method. It becomes clear that the 5-th space harmonic field which is due to the ground levitation coils, is a dominant factor in the eddy currents of the outer-vessel, and that a concentration of the currents occurs in the corner on the inner side of the bottom of the cryostat outer-vessel. Designs such as the distance between the two arrays of the ground levitation coils, and the lateral location of the induction coils of the power generator are also discussed
Theory and numerical calculation of the acoustic field exerted by eddy-current forces
Energy Technology Data Exchange (ETDEWEB)
Kawashima, K.
1976-01-01
The equations for calculating the acoustic field produced within a nonmagnetic metal by interaction of eddy currents with a static magnetic field were obtained on the assumptions (1) an ultrasonic wave is generated by the electromagentic force through classical and macroscopic phenomena; (2) the electric, magnetic, and elastic properties of the metal are linear, isotropic, and homogeneous throughout the metal, which occupies semi-infinite space; (3) the whole system is axially symmetric; and (4) eddy currents and elastic waves show a steady-state sinusoidal variation. The acoustic field produced by a specific electromagnetic ultrasonic transducer with axial symmetry was calculated numerically, and the results showed a well-defined ultrasonic wave beam, which was narrower than had been expected from the size of the transducer. (auth)
Reduction of magneto rheological dampers stiffness by incorporating of an eddy current damper
Asghar Maddah, Ali; Hojjat, Yousef; Reza Karafi, Mohammad; Reza Ashory, Mohammad
2017-05-01
In this paper, a hybrid damper is developed to achieve lower stiffness compared to magneto rheological dampers. The hybrid damper consists of an eddy current damper (ECD) and a Magneto Rheological Damper (MRD). The aim of this research is to reduce the stiffness of MRDs with equal damping forces. This work is done by adding an eddy current passive damper to a semi-active MRD. The ECDs are contactless dampers which show an almost viscous damping behavior without increasing the stiffness of a system. However, MRDs increase damping and stiffness of a system simultaneously, when a magnetic field is applied. Damping of each part is studied theoretically and experimentally. A semi-empirical model is developed to explain the viscoelastic behavior of the damper. The experimental results showed that the hybrid damper is able to dissipate energy as much as those of MRDs while its stiffness is 12% lower at a zero excitation current.
Enhanced vortex damping by eddy currents in superconductor-semiconductor hybrids
Danckwerts; Goni; Thomsen; Eberl; Rojo
2000-04-17
An enhancement of vortex-motion damping in thin Pb/In superconducting films is obtained through coupling to an adjacent two-dimensional electron gas formed in a modulation-doped GaAs/AlGaAs heterostructure. This effect is observed by monitoring the power dissipation in the superconductor in the vortex state while increasing the density of the electron gas using a gate voltage. Quantitative agreement is found with calculations based on a viscous damping model which considers generation of eddy currents in the electron gas by moving flux lines. In the regime of filamentary vortex flow, eddy-current damping leads to a striking dissipation breakdown due to the stopping of entire vortex channels.
New signal processing methods for the evaluation of eddy current NDT data
International Nuclear Information System (INIS)
Anon.
1987-01-01
Signal processing and pattern recognition methods play a crucial role in a number of areas associated with nondestructive evaluation. Defect characterization schemes often involve mapping the signal onto an appropriate feature domain and using pattern recognition techniques for classification. In addition, signal processing methods are also used to acquire, enhance, restore, and compress data. EPRI Project RP 2673-4 is concerned with developing new signal processing and pattern recognition techniques for evaluating eddy current signals. Efforts under this project have focused on three closely related areas. The thrust has been to: (1) develop a scheme to compress eddy current signals for the purposes of storing them in a compact form, (2) develop a robust clustering algorithm capable of discarding feature vectors that fall in the gray areas between clusters, and (3) investigate the feasibility of designing and developing a digital eddyscope
Computer programs for the acquisition and analysis of eddy-current array probe data
International Nuclear Information System (INIS)
Pate, J.R.; Dodd, C.V.
1996-07-01
Objective of the Improved Eddy-Curent ISI (in-service inspection) for Steam Generators Tubing program is to upgrade and validate eddy-current inspections, including probes, instrumentation, and data processing techniques for ISI of new, used, and repaired steam generator tubes; to improve defect detection, classification and characterization as affected by diameter and thickness variations, denting, probe wobble, tube sheet, tube supports, copper and sludge deposits, even when defect types and other variables occur in combination; to transfer this advanced technology to NRC's mobile NDE laboratory and staff. This report documents computer programs that were developed for acquisition of eddy-current data from specially designed 16-coil array probes. Complete code as well as instructions for use are provided
Tridimensional numerical modelling of an eddy current non destructive testing process
International Nuclear Information System (INIS)
Bonnin, O.; Chavant, C.; Giordano, P.
1993-01-01
This paper presents the numerical modelling of a new eddy current inspection process. The originality of the process, developed jointly by IFREMER and the CEA, lies in the mode of inducing the currents in the component to be tested. The TRIFOU eddy current calculation code is used for the modelling, which is in 3D. It is shown that a crack in the component inspected will cause localized disturbance of the currents induced. If we then focus on this disturbance, assuming the electrical behaviour of the materials to be linear, the resulting problem can be set for a limited geometrical area, leading to an appreciable saving in machine time. It is also shown that the computed and experimental results are quantitatively similar. (authors). 2 figs., 6 refs
Garter spring location of pressure tube for PHWR using eddy current testing methods
International Nuclear Information System (INIS)
Lee, Y. S.; Yang, D. J.; Jeong, H. K.
2001-01-01
There are garter springs between pressure tube and calandria tube for PHWR. If the space of these garter springs become to be changed, the sagging of tube is caused and the contact between the pressure tube and calandria tube will cause the tube to be failed. AECL has applied the eddy current testing methods using send-receive type probe for this purpose, but this study apply eddy current testing methods using bobbin differential type probe to detection of garter spring location. And we did the computer simulation using VIC-3D code and compared it with experiments results for inspection 1 ∼ 11kHz. The results was that the garter spring signal was successfully detected for every frequency, and 5 kHz was best
Numerical modeling of thermal fatigue cracks from the viewpoint of eddy current testing
International Nuclear Information System (INIS)
Yusa, Noritaka; Hashizume, Hidetoshi; Virkkunen, Iikka; Kemppainen, Mika
2012-01-01
This study discusses a suitable numerical modeling of a thermal fatigue crack from the viewpoint of eddy current testing. Five artificial thermal fatigue cracks, introduced into type 304L austenitic stainless steel plates with a thickness of 25 mm, are prepared; and eddy current inspections are carried out to gather signals using an absolute type pancake probe and a differential type plus point probe. Finite element simulations are then carried out to evaluate a proper numerical model of the thermal fatigue cracks. In the finite element simulations, the thermal fatigue cracks are modeled as a semi-elliptic planar region on the basis of the results of the destructive tests. The width and internal conductivity are evaluated by the simulations. The results of the simulations reveal that the thermal fatigue cracks are regarded as almost nonconductive when the internal conductivity is assumed to be uniform inside. (author)
Automated WWER steam generator eddy current testing and plugging control system
International Nuclear Information System (INIS)
Gorecan, I.; Gortan, K.; Grzalja, I.
2004-01-01
The structural architecture of the system contains three main components which are described as follows: Manipulator Guidance System; Eddy Current Testing System; Plugging System. The manipulator system has the task to position the end-effectors to the desired tube position. When the final position is reached, the Eddy Current testing system performs data acquisition. In case defects are found, the plugging system performs tube plug installment. Each system is composed of 3 layers. The first layer is the hardware layer consisting of motors driving the effectors along with sensors needed to obtain the positioning data, pusher motors used to push the test probes into tubes of the WWER steam generator, and plugging hardware tool. The second layer is the control box performing basic monitoring and control routines as an interconnection between first and third layer. The highest layer is the control software, running on the PC, which is used as a human-machine-interface.(author)
Mechanical impacts of poloidal eddy currents on the continuous vacuum vessel of a tokamak
International Nuclear Information System (INIS)
In, Sang Ryul; Yoon, Byung Joo.
1996-11-01
Poloidal eddy currents are induced on the continuous torus vacuum vessel by changes of the toroidal field during the machine start-up (toroidal field coil charge), shut-down (toroidal field coil discharge) and plasma disruption (plasma diamagnetism change). Analytic forms for the eddy currents flowing on the vessel, consequent pressures and forces acting on it are presented in this report. The results are applied to typical operation modes of the KT-2 tokamak. Stress analysis for two typical operation modes of toroidal field damping during a machine shut-gown and plasma energy quench during a plasma disruption were carried out using 3D FEM code (ANSYS 5.2). (author). 5 tabs., 22 figs., 9 refs
Detection of the Thickness Variation of a Stainless Steel sample using Pulsed Eddy Current
International Nuclear Information System (INIS)
Cheong, Y. M.; Angani, C. S.; Park, D. G.; Jhong, H. K.; Kim, G. D.; Kim, C. G.
2008-01-01
The Pulsed Eddy Current (PEC) system has been developed for the detection of thickness variation of stainless steel. The sample was machined as step configuration using stainless steel for thickness variation from 1mm to 5mm step by step. The LabView computer program was developed to display the variation in the amplitude of the detected pulse by scanning the PECT probe on the flat side of the sample. The pickup Sensor measures the effective magnetic field on the sample, which is the sum of the incident field and the field reflected by the specimen due to the induced eddy currents in the sample. We use the hall sensor for the detection. Usage of hall sensor instead of coil as a field detector improves the detectability and special resolution. This technology can be used in detection of local wall thinning of the pipeline of nuclear power plant
Study of eddy current power loss from outer-winding coils of a magnetic position sensor
International Nuclear Information System (INIS)
Liu, C.-P.; Lin, T.-K.; Chang, Y.-H.; Yu, C.-S.; Wu, K.-T.; Wang, S.-J.; Ying, T.-F.; Huang, D.-R.
2000-01-01
The present analysis is concerned with eddy current power loss of a magnetic position sensor, which arises from a non-uniform flux linkage distribution between magnetic material and position sensor. In the paper, a magnetic position sensor system is simplified to be an outer-winding coil along the axial direction of a low carbon steel bar, and developed a numerical model to compute the electrical characteristics by an excited current source. According to the simulated and measured data in this proposed model from 2.52 to 11.37 Oes, eddy current power losses of conducting material have a variation of 6.1% and 9.77%, respectively. Finally, the phases of waveform of the induced output voltage will also be obtained in the conducting material, and have a variation of 3.68% obtained by using the current source in the proposed model
Study of eddy current power loss from outer-winding coils of a magnetic position sensor
Liu, C P; Chang, Y H; Yu, C S; Wu, K T; Wang, S J; Ying, T F; Huang, D R
2000-01-01
The present analysis is concerned with eddy current power loss of a magnetic position sensor, which arises from a non-uniform flux linkage distribution between magnetic material and position sensor. In the paper, a magnetic position sensor system is simplified to be an outer-winding coil along the axial direction of a low carbon steel bar, and developed a numerical model to compute the electrical characteristics by an excited current source. According to the simulated and measured data in this proposed model from 2.52 to 11.37 Oes, eddy current power losses of conducting material have a variation of 6.1% and 9.77%, respectively. Finally, the phases of waveform of the induced output voltage will also be obtained in the conducting material, and have a variation of 3.68% obtained by using the current source in the proposed model.
A method for crack sizing using Bayesian inference arising in eddy current testing
International Nuclear Information System (INIS)
Kojima, Fumio; Kikuchi, Mitsuhiro
2008-01-01
This paper is concerned with a sizing methodology of crack using Bayesian inference arising in eddy current testing. There is often uncertainty about data through quantitative measurements of nondestructive testing and this can yield misleading inference of crack sizing at on-site monitoring. In this paper, we propose optimal strategies of measurements in eddy current testing using Bayesian prior-to-posteriori analysis. First our likelihood functional is given by Gaussian distribution with the measurement model based on the hybrid use of finite and boundary element methods. Secondly, given a priori distributions of crack sizing, we propose a method for estimating the region of interest for sizing cracks. Finally an optimal sensing method is demonstrated using our idea. (author)
Coupling method of magnetic memory and eddy current nondestructive testing for retired crankshafts
International Nuclear Information System (INIS)
Ni, Chen; Hua, Lin; Wang, Xiaokai; Wang, Zhou; Qin, Xunpeng; Fang, Zhou
2016-01-01
To verify the validity of the Coupling method of magnetic memory and eddy current (CMMEC) testing for crankshafts, we use this technique to test a 12-cylinder V-design diesel crankshaft. First, the stress distribution in the crankshaft was obtained under 12 working conditions using a Finite element (FE) model that complied with the commercial FE code ABAQUS. Second, Magnetic memory testing (MMT) and Eddy current testing (ECT) were adopted to detect the regions of stress concentration in the crankshaft and the specific location of cracks based on simulation results. Lastly, magnetic particle testing was conducted to detect and display the corresponding crack to verify the CMMEC testing results. The MMT and ECT results can provide basis and guidance for the remanufacture and life evaluation of retired crankshafts.
Method of correcting eddy current magnetic fields in particle accelerator vacuum chambers
Danby, Gordon T.; Jackson, John W.
1991-01-01
A method for correcting magnetic field aberrations produced by eddy currents induced in a particle accelerator vacuum chamber housing is provided wherein correction windings are attached to selected positions on the housing and the windings are energized by transformer action from secondary coils, which coils are inductively coupled to the poles of electro-magnets that are powered to confine the charged particle beam within a desired orbit as the charged particles are accelerated through the vacuum chamber by a particle-driving rf field. The power inductively coupled to the secondary coils varies as a function of variations in the power supplied by the particle-accelerating rf field to a beam of particles accelerated through the vacuum chamber, so the current in the energized correction coils is effective to cancel eddy current flux fields that would otherwise be induced in the vacuum chamber by power variations in the particle beam.
Fourier descriptor classification of differential eddy current probe impedance plane trajectories
International Nuclear Information System (INIS)
Lord, W.; Satish, S.R.
1984-01-01
This chapter describes the use of a parametric model for representing the two-dimensional eddy current impedance plane trajectory. The main advantage of this approach is the ability to reconstruct the trajectory from the model coefficients. Fourier descriptors are used to facilitate defect classification. The Fourier descriptors are obtained by expanding the complex contour function in a Fourier series. Functions of Fourier coefficients which are invariant under transformation of the trajectory are derived and incorporated into a feature vector. Defect classification is obtained by using the K-Means algorithm to cluster the feature vectors. It is demonstrated that the Fourier descriptor approach represents a powerful tool which have several advantages over nonparametric approaches including its insensitivity to drift in the eddy current instrument as well as variations in the probe speed
The application of neural network for the advancement of the eddy current testing
International Nuclear Information System (INIS)
Sakai, T.; Soneda, N.
1996-01-01
All the steam generator (SG) tubes of Japanese pressurized water reactors (PWRs) are inspected by the eddy current testing (ECT) method in every annual scheduled inspection. Here, a neural network system to estimate the class and size of defects from signals obtained by the eddy current testing (ECT) method has been developed. A trajectory of ECT signal is characterized by four representative parameters, and totally eight parameters obtained from two trajectories by different AC current frequencies are used as input parameters for neutral networks. A probabilistic descent method is employed to minimize the error at the learning process of neural networks. It is indicated that using multiple neutral networks which are separately responsible to each class of defects is effective to the improvement of their estimation accuracy. And, it is demonstrated that the neural network system which the authors developed can estimate the class and size of defects from unlearned trajectories with high accuracy
A Steel Ball Surface Quality Inspection Method Based on a Circumferential Eddy Current Array Sensor
Directory of Open Access Journals (Sweden)
Huayu Zhang
2017-07-01
Full Text Available To efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor, magnetic field intensity, and induced eddy current density on the surface of a sample steel ball, was determined using 3-, 4-, 5-, and 6-coil probes, for analysis and comparison. The optimal lift-off from the measured steel ball, the number of probe coils, and the frequency of excitation current suitable for steel ball inspection were obtained. Using the resulting CECA sensor to inspect 46,126 steel balls showed a miss rate of ~0.02%. The sensor was inspected for surface defects as small as 0.05 mm in width and 0.1 mm in depth.
International Nuclear Information System (INIS)
Alencar, Donizete A.; Silva Junior, Silverio F.
2011-01-01
Eddy current is a very important NDT inspection method widely used to perform integrity evaluation of tubes installed in heat exchangers. For nuclear power plants, a classical example is the remote inspection of steam generators and condensers, as well as other ordinary auxiliary equipment. Data evaluation can be performed by means of precise phase and amplitude measurements of complex impedance signals, represented as Lissajous figures plotted on the screen of the inspection systems. This paper presents the software EASY, a computer assisted analysis system developed at CDTN to help the characterization of volumetric discontinuities present in heat exchangers tubes. Data to be analyzed are obtained from commercial eddy current equipment data file, such as ECT MAD8D. Main advantage of that system is its portability and easy use, since it can be executed in ordinary PC, under Microsoft Windows operating system. (author)
Energy Technology Data Exchange (ETDEWEB)
Alencar, Donizete A.; Silva Junior, Silverio F., E-mail: daa@cdtn.b, E-mail: silvasf@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
2011-07-01
Eddy current is a very important NDT inspection method widely used to perform integrity evaluation of tubes installed in heat exchangers. For nuclear power plants, a classical example is the remote inspection of steam generators and condensers, as well as other ordinary auxiliary equipment. Data evaluation can be performed by means of precise phase and amplitude measurements of complex impedance signals, represented as Lissajous figures plotted on the screen of the inspection systems. This paper presents the software EASY, a computer assisted analysis system developed at CDTN to help the characterization of volumetric discontinuities present in heat exchangers tubes. Data to be analyzed are obtained from commercial eddy current equipment data file, such as ECT MAD8D. Main advantage of that system is its portability and easy use, since it can be executed in ordinary PC, under Microsoft Windows operating system. (author)
Eddy current testing with high penetration; WS-Pruefungen mit grosser Eindringtiefe
Energy Technology Data Exchange (ETDEWEB)
Becker, R.; Kroening, M. [Fraunhofer Inst. fuer Zerstoerungsfreie Pruefverfahren, Saarbruecken (Germany)
1999-08-01
The low-frequency eddy current testing method is used when penetration into very deep layers is required. The achievable penetration depth is determined among other parameters by the lowest testing frequency that can be realised together with the eddy current sensor. When using inductive sensors, the measuring effect declines proportional to the lowering frequency (induction effect). Further reduction of testing frequency requires other types of sensors, as e.g. the GMR (Giant Magnetic Resistance), which achieves a constant measuring sensitivity down to the steady field. The multi-frequency eddy current testing method MFEC 3 of IZFP described here can be operated using three different scanning frequencies at a time. Two variants of eddy current probes are used in this case. Both have an inductive winding at their emitters, of the type of a measuring probe. The receiver end is either also an inductive winding, or a magnetic field-responsive resistance (GMR). (orig./CB) [Deutsch] Das Niederfrequenz(NF)-Wirbelstrom(WS)-Verfahren wird eingesetzt, um eine grosse Eindringtiefe zu erzielen. Die erreichbare Tiefenreichweite wird u.a. durch die niedrigste Prueffrequenz bestimmt, die zusammen mit dem Wirbelstrom-Sensor realisiert werden kann. Bei Einsatz von induktiven Sensoren geht mit abnehmender Prueffrequenz der Messeffekt proportional zurueck (Induktionswirkung). Eine weitere Absenkung der Prueffrequenzen macht den Einsatz von andersartigen Sensoren notwendig, z.B. den GMR (Giant Magnetic Resistance), der eine gleichmaessige Messempfindlichkeit bis zum Gleichfeld besitzt. Das eingesetzte Mehrfrequenz-Wirbelstrom-Pruefverfahren MFEC 3 des IZFP arbeitet mit drei gleichzeitig eingespeisten Prueffrequenzen. Dabei werden zwei Varianten von WS-Sensoren eingesetzt. Beide besitzen auf der Senderseite eine induktive Wicklung in der Art einer Tastsonde. Die Empfaengerseite ist entweder ebenfalls eine induktive Wicklung oder ein magnetfeldempfindlicher Widerstand (GMR). (orig./DGE)
Automation of inspection methods for eddy current testing of steam generator tubes
International Nuclear Information System (INIS)
Meurgey, P.; Baumaire, A.
1990-01-01
Inspection of all the tubes of a steam generator when the reactor is stopped is required for some of these exchangers affected by stress corrosion cracking. Characterization of each crack, in each tube is made possible by the development of software for processing the signals from an eddy current probe. The ESTELLE software allows a rapid increase of tested tubes, more than 80,000 in 1989 [fr
Numeric signal analysis process, with particular application to eddy current testing
International Nuclear Information System (INIS)
Combes, J.Y.; Ledinghen, E. de; Lionti, F.
1996-01-01
Eddy current testing uses analogic demodulation process, and then analog or digital phase shift measurement. These techniques are efficient, but not always versatile enough to apply to different configurations, in particular when a change of operating frequency is requested. This method performs an entirely digital conditioning. Excitation is simultaneously performed at N different frequencies (typically N=4). By sampling at a much higher frequency, 2N equation are obtained, allowing the resolution of the linear equations system. (D.L.)
Process for treating signals returning by an eddy current absolute punctual probe
International Nuclear Information System (INIS)
Attaqui, P.; Benoist, B.; Besnard, R.; David, B.
1994-01-01
The method of signal treatment involves returning signals to eddy currents moving along an internal surface of a tube. A signal representing the state of the surface is delivered and the surface is swept based on a given order of elementary measurement zones. Values of samples of a signal are registered for each zone giving a three dimensional image of the surface. A background noise surface is constructed and substracted from the image. 7 figs
Eddy Current Transducer Dedicated for Sigma Phase Evaluation in Duplex Stainless Steel
Directory of Open Access Journals (Sweden)
Grzegorz Psuj
2012-01-01
Full Text Available The paper describes a new transducer dedicated for evaluation of a duplex stainless steel (DSS. Different phases which exist in DSS have influence on mechanical as well as on electrical properties. Therefore, an eddy current transducer was utilized. In order to achieve high sensitivity, a differential type of the transducer was selected. The performance of the transducer was verified by utilizing the samples which had a different amount of sigma phase.
International Nuclear Information System (INIS)
Bottauscio, Oriano.; Canova, Aldo; Chiampi, Mario; Repetto, Maurizio
2003-01-01
The magnetic analysis of stators of electrical motors is performed through an innovative 2D finite element formulation that takes into account the effects of eddy currents within the laminations by means of a generalized constitutive relationship also including vector hysteresis. This approach is applied to a deep estimation of magnetic flux distribution and magnetic losses in stator of induction motors supplied by high-frequency sinusoidal or six-step voltage sources
International Nuclear Information System (INIS)
Carpenter, K.H.
1976-11-01
A description is given of FORTRAN programs for transient eddy current calculations in thin, non-magnetic conductors using a perturbation-polynomial expansion technique. Basic equations are presented as well as flow charts for the programs implementing them. The implementation is in two steps--a batch program to produce an intermediate data file and interactive programs to produce graphical output. FORTRAN source listings are included for all program elements, and sample inputs and outputs are given for the major programs
The DECMU: a digital device for delayed analysis of multi-frequency eddy current signals
International Nuclear Information System (INIS)
Pigeon, Michel.
1981-08-01
A delayed data analysis system has been realized by the CEA and Intercontrole for in-service inspection of steam generators of nuclear plants by multifrequency eddy current testing. This device allows, out of the plant, adjustment during switching of the probes, graph recording and analysis for defect signal qualification. The equipment contains an analog mixing device, as IC3FA multi-frequency appartus, but has in addition a memory allowing data cycling and signal isolation for adjustment or analysis [fr
An integrated automatic system for the eddy-current testing of the steam generator tubes
Energy Technology Data Exchange (ETDEWEB)
Woo, Hee Gon; Choi, Seong Su [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center
1995-12-31
This research project was focused on automation of steam generator tubes inspection for nuclear power plants. ECT (Eddy Current Testing) inspection process in nuclear power plants is classified into 3 subprocesses such as signal acquisition process, signal evaluation process, and inspection planning and data management process. Having been automated individually, these processes were effectively integrated into an automatic inspection system, which was implemented in HP workstation with expert system developed (author). 25 refs., 80 figs.
Quality Assessment of Refractory Protective Coatings Using Multi-Frequency Eddy Current MWM-Arrays
International Nuclear Information System (INIS)
Zilberstein, Vladimir; Evans, Leslie; Huguenin, Carolene; Grundy, David; Lyons, Robert; Goldfine, Neil; Mulligan, Christopher
2006-01-01
Demands for increased range, rate of fire, and muzzle velocity have prompted development of new refractory metal coatings. Nondestructive measurement of coating electrical conductivity and thickness is crucial to the process development and statistical process control. This paper presents absolute property coating characterization results for Ta coatings obtained with a Meandering Winding Magnetometer (MWM registered ) eddy-current sensor and MWM-Array sensor. The measured coating conductivity indicates the ratio of the intended α-Ta to the undesirable β-Ta
Investigating discrimination model of the signals obtained by eddy current testing
International Nuclear Information System (INIS)
Wache, G.; Rivenez, J.
1986-01-01
A software using an eddy current system controlled by a desk computer has been developed in order to separate a characteristic physical value among several parts. The numerical process involved uses multiparameter measurements done previously on significant parts belonging to the same class. The analysis presented deals with hardness testing of steel bolts in relation with heat-treatment, but other applications dealing with either micro structure check or defect investigation, could be done in the future by using a similar method
Analytical model development of an eddy-current-based non-contacting steel plate conveyance system
International Nuclear Information System (INIS)
Liu, C.-T.; Lin, S.-Y.; Yang, Y.-Y.; Hwang, C.-C.
2008-01-01
A concise model for analyzing and predicting the quasi-static electromagnetic characteristics of an eddy-current-based non-contacting steel plate conveyance system has been developed. Confirmed by three-dimensional (3-D) finite element analysis (FEA), adequacy of the analytical model can be demonstrated. Such an effective approach, which can be conveniently used by the potential industries for preliminary system operational performance evaluations, will be essential for designers and on-site engineers
Detection of milled 100Cr6 steel surface by eddy current and incremental permeance methods
Czech Academy of Sciences Publication Activity Database
Perevertov, Oleksiy; Neslušan, M.; Stupakov, Alexandr
2017-01-01
Roč. 87, Apr (2017), s. 15-23 ISSN 0963-8695 R&D Projects: GA ČR GB14-36566G; GA ČR GA13-18993S Institutional support: RVO:68378271 Keywords : Eddy currents * hard milling * incremental permeance * magnetic materials * surface characterization Subject RIV: JB - Sensors, Measurment, Regulation OBOR OECD: Electrical and electronic engineering Impact factor: 2.726, year: 2016
Automated eddy-current installation AVD-01 for detecting flaws in fuel element cans
International Nuclear Information System (INIS)
Varvaritsa, V.P.; Martishchenko, L.G.; Popov, V.K.; Romanov, M.L.; Shlepnev, I.O.; Shmatok, V.P.
1986-01-01
This paper describes an automated installation for eddy-current flaw detection in thin-walled pipes with small diameter; its unified transport system makes it possible to use the installation in inspection lines and production lines of fuel elements. The article describes the structural diagrams of the installation and presents the results of investigations connected with the selection for establishing the optimum regimes and sensitivity of feedthrough transducers with focusing screens
Post-tensioning tendon force loss detection using low power pulsed eddy current measurement
Kim, Ji-Min; Lee, Jun; Sohn, Hoon
2018-04-01
In the field of bridge engineering, pre-fabrication of a bridge member and its construction in site have been issued and studied, which achieves improved quality and rapid construction. For integration of those pre-fabricated segments into a structural member (i.e., a concrete slab, girder and pier), post-tensioning (PT) technique is adopted utilizing a high-strength steel tendon, and an effective investigation of the remaining PT tendon force is essential to assure an overall structural integrity. This study proposes a pulsed eddy current based tendon force loss detection system. A compact eddy current sensor is designed to be installed on the surface of an anchor holding a steel PT tendon. The intensity of the induced eddy current varies with PT tendon force alteration due to the magnetostriction effect of a ferromagnetic material. The advantages of the proposed system are as follows: (1) low power consumption, (2) rapid inspection, and (3) simple installation. Its performance was validated experimentally in a full-scale lab test of a 3.3-m long, 15.2-mm diameter mono-tendon that was tensioned using a universal testing machine. Tendon force was controlled from 20 to 180 kN with 20 kN interval, and eddy current responses were measured and analyzed at each force condition. The proposed damage index and the amount of force loss of PT tendon were monotonically related, and an excessive loss as much as 30 % of an initially-introduced tendon force was successfully predicted.
In-service examination of IHX tubing with eddy current NDT equipment
International Nuclear Information System (INIS)
Brown, R.L.
1972-01-01
Single and multiple frequency eddy current (ET) nondestructive testing (NDT) techniques and equipment were investigated for in-service inspection of sodium-contaminated intermediate heat exchanger (IHX) tubing. A four frequency technique, demonstrated in the laboratory, was relatively insensitive to signals caused by probe motion, tube support plates, and residual sodium on the outer surface of the tubes. No method was found to avoid the signals from residual sodium on the inside surfaces of the tube. (U.S.)
Directory of Open Access Journals (Sweden)
Sergio Saludes-Rodil
2015-04-01
Full Text Available An unsupervised approach to classify surface defects in wire rod manufacturing is developed in this paper. The defects are extracted from an eddy current signal and classified using a clustering technique that uses the dynamic time warping distance as the dissimilarity measure. The new approach has been successfully tested using industrial data. It is shown that it outperforms other classification alternatives, such as the modified Fourier descriptors.
An integrated automatic system for the eddy-current testing of the steam generator tubes
Energy Technology Data Exchange (ETDEWEB)
Woo, Hee Gon; Choi, Seong Su [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center
1996-12-31
This research project was focused on automation of steam generator tubes inspection for nuclear power plants. ECT (Eddy Current Testing) inspection process in nuclear power plants is classified into 3 subprocesses such as signal acquisition process, signal evaluation process, and inspection planning and data management process. Having been automated individually, these processes were effectively integrated into an automatic inspection system, which was implemented in HP workstation with expert system developed (author). 25 refs., 80 figs.
Assessment of eddy current effects on compression experiments in the TFTR tokamak
International Nuclear Information System (INIS)
Wong, K.L.; Park, W.
1986-05-01
The eddy current induced on the TFTR vacuum vessel during compression experiments is estimated based on a cylindrical model. It produces an error magnetic field that generates magnetic islands at the rational magnetic surfaces. The widths of these islands are calculated and found to have some effect on electron energy confinement. However, resistive MHD simulation results indicate that the island formation process can be slowed down by plasma rotation
Mathematical and numerical models for eddy currents and magnetostatics with selected applications
Rappaz, Jacques
2013-01-01
This monograph addresses fundamental aspects of mathematical modeling and numerical solution methods of electromagnetic problems involving low frequencies, i.e. magnetostatic and eddy current problems which are rarely presented in the applied mathematics literature. In the first part, the authors introduce the mathematical models in a realistic context in view of their use for industrial applications. Several geometric configurations of electric conductors leading to different mathematical models are carefully derived and analyzed, and numerical methods for the solution of the obtained problem
Integrodifferential approach to solution of eddy currents in linear structures with motion
Czech Academy of Sciences Publication Activity Database
Doležel, Ivo; Karban, P.; Donátová, M.; Šolín, Pavel
2010-01-01
Roč. 80, č. 8 (2010), s. 1636-1646 ISSN 0378-4754 R&D Projects: GA ČR(CZ) GA102/07/0496 Institutional research plan: CEZ:AV0Z20570509 Keywords : eddy currents * integrodifferential approach * numerical analysis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.812, year: 2010 www.elsevier.com/locate/matcom
Bui-Thanh, T.; Girolami, M.
2014-11-01
We consider the Riemann manifold Hamiltonian Monte Carlo (RMHMC) method for solving statistical inverse problems governed by partial differential equations (PDEs). The Bayesian framework is employed to cast the inverse problem into the task of statistical inference whose solution is the posterior distribution in infinite dimensional parameter space conditional upon observation data and Gaussian prior measure. We discretize both the likelihood and the prior using the H1-conforming finite element method together with a matrix transfer technique. The power of the RMHMC method is that it exploits the geometric structure induced by the PDE constraints of the underlying inverse problem. Consequently, each RMHMC posterior sample is almost uncorrelated/independent from the others providing statistically efficient Markov chain simulation. However this statistical efficiency comes at a computational cost. This motivates us to consider computationally more efficient strategies for RMHMC. At the heart of our construction is the fact that for Gaussian error structures the Fisher information matrix coincides with the Gauss-Newton Hessian. We exploit this fact in considering a computationally simplified RMHMC method combining state-of-the-art adjoint techniques and the superiority of the RMHMC method. Specifically, we first form the Gauss-Newton Hessian at the maximum a posteriori point and then use it as a fixed constant metric tensor throughout RMHMC simulation. This eliminates the need for the computationally costly differential geometric Christoffel symbols, which in turn greatly reduces computational effort at a corresponding loss of sampling efficiency. We further reduce the cost of forming the Fisher information matrix by using a low rank approximation via a randomized singular value decomposition technique. This is efficient since a small number of Hessian-vector products are required. The Hessian-vector product in turn requires only two extra PDE solves using the adjoint
Pulsed eddy current inspection system for nondestructive examination of irradiated fuel rods
International Nuclear Information System (INIS)
Yancey, M.E.
1979-01-01
An inspection system has been developed for nondestructive examination of irradiated fuel rods utilizing pulsed eddy current techniques. The system employs an encircling type pulsed eddy current transducer capable of sensing small defects located on both the inner and outer diameter fuel rod surfaces during a single scan. Pulsed eddy current point probes are used to provide fuel rod wall thikness data and an indication of radial defect location. Two linear variable differential transformers are used to provide information on fuel rod diameter variation. A microprocessor based control system is used to automatically scan fuel rods up to 4.06 meters in length at predetermined radial locations. Defects as small as 0.005 cm deep by 0.254 cm long by 0.005 cm wide have been detected on outside diameter surfaces of a 1.43 cm outside diameter fuel rod cladding with a 0.094 cm wall thickness and 0.010 cm deep by 0.254 cm long by 0.005 cm wide on the inside diameter surface
Eddy-Current Testing of Welded Stainless Steel Storage Containers to Verify Integrity and Identity
International Nuclear Information System (INIS)
Tolk, Keith M.; Stoker, Gerald C.
1999-01-01
An eddy-current scanning system is being developed to allow the International Atomic Energy Agency (IAEA) to verify the integrity of nuclear material storage containers. Such a system is necessary to detect attempts to remove material from the containers in facilities where continuous surveillance of the containers is not practical. Initial tests have shown that the eddy-current system is also capable of verifying the identity of each container using the electromagnetic signature of its welds. The DOE-3013 containers proposed for use in some US facilities are made of an austenitic stainless steel alloy, which is nonmagnetic in its normal condition. When the material is cold worked by forming or by local stresses experienced in welding, it loses its austenitic grain structure and its magnetic permeability increases. This change in magnetic permeability can be measured using an eddy-current probe specifically designed for this purpose. Initial tests have shown that variations of magnetic permeability and material conductivity in and around welds can be detected, and form a pattern unique to the container. The changes in conductivity that are present around a mechanically inserted plug can also be detected. Further development of the system is currently underway to adapt the system to verifying the integrity and identity of sealable, tamper-indicating enclosures designed to prevent unauthorized access to measurement equipment used to verify international agreements
Development of uniform eddy current multi-probe for flaw detection on complex shape part
International Nuclear Information System (INIS)
Fukuoka, Katsuhiro; Hashimoto, Mitsuo
2007-01-01
The establishment of the technology that inspects plant structures nondestructive is requested, because the occurrence of cracks is reported in the structures of nuclear power plants. In this research, a uniform eddy current multi-probe that is able to be applied to the complex structure and inspected the cracks at the high speed was developed. Exciting coils of the uniform eddy current multi-probe were designed the shape that agreed with the complex shape part, and so that the eddy current flows uniformly in the part of pick-up coils. The pick-up coils were arranged on a flexible printed circuit board as it was possible to correspond to the complex shape. The detection characteristics of EDM (electro-discharge machining) slits provided on the complex shape part were evaluated. The clear signals for the EDM slits provided on the curvature surface of 25 mm in radius were obtained by this probe. We confirmed that the crack shape was able to be estimated by the detection signals. (author)
Evaluation of stress corrosion cracking as a function of its resistance to eddy currents
International Nuclear Information System (INIS)
Yusa, Noritaka; Hashizume, Hidetoshi
2009-01-01
This study discusses the equivalent conductivity, the equivalent width, and the equivalent resistance of stress corrosion cracks from the viewpoint of eddy current testing. Four artificial stress corrosion cracks were prepared for this study, and their eddy current signals were gathered using two absolute pancake probes and two differential type plus point probes. Then their numerical models were evaluated using finite element simulations on the basis of the measured eddy current signals and their profiles revealed by destructive tests. The results of this study revealed that whereas the equivalent conductivity and the equivalent width depend on the exciting frequency utilized, the equivalent resistance of a crack has much less dependency, which agrees well with an earlier report. This study also revealed that the resistance of a crack depends on probe utilized. Larger probes tend to lead to smaller crack resistance. Pancake type probes tend to lead to larger crack resistance than plus point probes. Analyzing the results together with earlier reports indicates that cracks with a large equivalent conductivity tend to have large equivalent width, and supports the validity of assuming the minimum resistance of a stress corrosion crack whereas considering the conductivity and the width individually would not be viable.
Removing Eddy-current probe wobble noise from steam generator tubes testing using wavelet transform
International Nuclear Information System (INIS)
Lopez, Luiz Antonio Negro Martin; Ting, Daniel Kao Sun; Upadhyaya, Belle R.
2005-01-01
One of the most import nondestructive evaluation (NDE) applied to steam generator tubes inspection is the electromagnetic Eddy-Current testing (ECT). The signals generated in this NDE, in general, contain many noises which make difficult the interpretation and analysis of ECT signals. One of the noises present in the signals is the probe wobble noise, which is caused by the existing slack between the probe and the tube. In this work, Wavelet Transform (WT) is used in the probe wobble de-noising. WT is a relatively recent mathematical tool, which allows local analysis of non stationary signals such as ECT signals. This is a great advantage of WT when compared with other analysis tools such as Fourier Transform. However, using WT involves wavelets and coefficients selection as well as choosing the number of decomposition level needed. This work presents a probe wobble de-noising method when used in conjunction with the traditional ECT evaluation. Comparative results using several WT applied do Eddy-Current signals are presented in a reliable way, in other words, without loss of inherent defect information. A stainless steel tube, with 2 artificial defects generated by electro-erosion, was inspected by a ZETEC MIZ-17ET ECT equipment. The signals were de-noised through several different WT and the results are presented. The method offer good results and is a promising method because allows for the removal of Eddy-Current signals probe wobble effect without loss of essential signal information. (author)
International Nuclear Information System (INIS)
Kaita, R.; Kozub, T.; Logan, N.; Majeski, R.; Menard, J.; Zakharov, L.
2010-01-01
The lithium tokamak experiment (LTX) is a modest-sized spherical tokamak (R 0 = 0.4 m and a = 0.26 m) designed to investigate the low-recycling lithium wall operating regime for magnetically confined plasmas. LTX will reach this regime through a lithium-coated shell internal to the vacuum vessel, conformal to the plasma last-closed-flux surface, and heated to 300-400 C. This structure is highly conductive and not axisymmetric. The three-dimensional nature of the shell causes the eddy currents and magnetic fields to be three-dimensional as well. In order to analyze the plasma equilibrium in the presence of three-dimensional eddy currents, an extensive array of unique magnetic diagnostics has been implemented. Sensors are designed to survive high temperatures and incidental contact with lithium and provide data on toroidal asymmetries as well as full coverage of the poloidal cross-section. The magnetic array has been utilized to determine the effects of nonaxisymmetric eddy currents and to model the start-up phase of LTX. Measurements from the magnetic array, coupled with two-dimensional field component modeling, have allowed a suitable field null and initial plasma current to be produced. For full magnetic reconstructions, a three-dimensional electromagnetic model of the vacuum vessel and shell is under development.
Open-loop correction for an eddy current dominated beam-switching magnet.
Koseki, K; Nakayama, H; Tawada, M
2014-04-01
A beam-switching magnet and the pulsed power supply it requires have been developed for the Japan Proton Accelerator Research Complex. To switch bunched proton beams, the dipole magnetic field must reach its maximum value within 40 ms. In addition, the field flatness should be less than 5 × 10(-4) to guide each bunched beam to the designed orbit. From a magnetic field measurement by using a long search coil, it was found that an eddy current in the thick endplates and laminated core disturbs the rise of the magnetic field. The eddy current also deteriorates the field flatness over the required flat-top period. The measured field flatness was 5 × 10(-3). By using a double-exponential equation to approximate the measured magnetic field, a compensation pattern for the eddy current was calculated. The integrated magnetic field was measured while using the newly developed open-loop compensation system. A field flatness of less than 5 × 10(-4), which is an acceptable value, was achieved.
Eddy current technique for detecting and sizing surface cracks in steel components
International Nuclear Information System (INIS)
Cecco, V.S.; Carter, J.R.; Sullivan, S.P.
1995-01-01
Cracking has occurred in pressure vessel nozzles and girth welds due to thermal fatigue. Pipe welds, welds in support structures, and welds in reactor vault liner panels in nuclear facilities have failed because of cracks. Cracking can also occur in turbine rotor bore surfaces due to high cycle fatigue. Dye penetrant, magnetic particle and other surface NDT methods are used to detect cracks but cannot be used for depth sizing. Crack depth can be measured with various NDT methods such as ultrasonic time-of-flight diffraction (TOFD), potential drop, and eddy current. The TOFD technique can be difficult to implement on nozzle welds and is best suited for sizing deep cracks (>5 mm). The conventional eddy current method is easy to implement, but crack sizing is normally limited to shallow cracks ( 2 mm) cracks. Eddy current testing (ET) techniques are readily amenable to remote/automatic inspections. These new probes could augment present magnetic particle (MT) and dye penetrant (PT) testing through provision of reliable defect depth information. Reliable crack sizing permits identification of critical cracks for plant life extension and licensing purposes. In addition, performing PT and MT generates low level radioactive waste in some inspection applications in nuclear facilities. Replacing these techniques with ET for some components will eliminate some of this radioactive waste. (author)
CANDU fuel sheath integrity and oxide layer thickness determination by Eddy current technique
International Nuclear Information System (INIS)
Gheorghe, Gabriela; Man, Ion; Parvan, Marcel; Valeca, Serban
2010-01-01
This paper presents results concerning the integrity assessment of the fuel elements cladding and measurements of the oxide layer on sheaths, using the eddy current technique. Flaw detection using eddy current provides information about the integrity of fuel element sheath or presence of defects in the sheath produced by irradiation. The control equipment consists of a flaw detector with eddy currents, operable in the frequency range 10 Hz to 10 MHz, and a differential probe. The calibration of the flaw detector is done using artificial defects (longitudinal, transversal, external and internal notches, bored and unbored holes) obtained on Zircaloy-4 tubes identical to those out of which the sheath of the CANDU fuel element is manufactured (having a diameter of 13.08 mm and a wall thickness of 0.4 mm). When analyzing the behavior of the fuel elements' cladding facing the corrosion is important to know the thickness of the zirconium oxide layer. The calibration of the device measuring the thickness of the oxide layer is done using a Zircaloy-4 tube identical to that which the cladding of the CANDU fuel element is manufactured of, and calibration foils, as well. (authors)
Eddy current array probe for detection of surface breaking cracks in the extrados of feeder bends
International Nuclear Information System (INIS)
Obrutsky, L.S.; Cassidy, R.A.; Chaplin, K.; Martin, P.; Bureau, J.F.
2006-01-01
A new eddy current array probe has been implemented as a straightforward and promising technique for detection of outer diameter (OD) surface-breaking cracks on the extrados of feeder bends. The design is based on previous work performed at AECL, which had demonstrated that eddy current probes with laterally displaced transmit-receive coils can overcome some of the limitations of inspecting ferritic steel components for surface-breaking cracks. The Feeder Integrity Joint Program-CANDU Owners Group Inc. (FIJP-COG) Non-Destructive Evaluation (NDE) Team members commissioned AECL to work in collaboration with the probe manufacturer ZETEC, to develop a field usable eddy current array probe. The objective was to acquire a technique with the following capabilities: fast scanning non-contact inspection technique for surface breaking discontinuities; full inspection of the bend extrados OD surface in a single scan; ability to inspect first and second bends with similar settings and capabilities; permanent record for future reference; axial and circumferential crack detection in a single scan; capability to detect OD surface-breaking cracks, which can provide additional information to that provided by ultrasonic testing (UT) for flaw characterization, and detection threshold: Surface breaking cracks equivalent to a 0.5 mm deep, 10 mm long EDM notch located on the OD of the bend extrados. This paper discusses the basis for probe design, summarizes the experimental work to evaluate probe capabilities and analyzes the results from the field trial. (author)
Eddy current array probe for detection of surface breaking cracks in the extrados of feeder bends
Energy Technology Data Exchange (ETDEWEB)
Obrutsky, L.S.; Cassidy, R.A.; Chaplin, K. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)]. E-mail: obrutskyl@aecl.ca; Martin, P. [NB Power, Point Lepreau NGS, Point Lepreau, New Brunswick (Canada)]. E-mail: PMartin@nbpower.com; Bureau, J.F. [Zetec, Quebec, Quebec (Canada)]. E-mail: jean-francois.bureau@zetec.com
2006-07-01
A new eddy current array probe has been implemented as a straightforward and promising technique for detection of outer diameter (OD) surface-breaking cracks on the extrados of feeder bends. The design is based on previous work performed at AECL, which had demonstrated that eddy current probes with laterally displaced transmit-receive coils can overcome some of the limitations of inspecting ferritic steel components for surface-breaking cracks. The Feeder Integrity Joint Program-CANDU Owners Group Inc. (FIJP-COG) Non-Destructive Evaluation (NDE) Team members commissioned AECL to work in collaboration with the probe manufacturer ZETEC, to develop a field usable eddy current array probe. The objective was to acquire a technique with the following capabilities: fast scanning non-contact inspection technique for surface breaking discontinuities; full inspection of the bend extrados OD surface in a single scan; ability to inspect first and second bends with similar settings and capabilities; permanent record for future reference; axial and circumferential crack detection in a single scan; capability to detect OD surface-breaking cracks, which can provide additional information to that provided by ultrasonic testing (UT) for flaw characterization, and detection threshold: Surface breaking cracks equivalent to a 0.5 mm deep, 10 mm long EDM notch located on the OD of the bend extrados. This paper discusses the basis for probe design, summarizes the experimental work to evaluate probe capabilities and analyzes the results from the field trial. (author)
Beck, Faith R.; Lind, R. Paul; Smith, James A.
2018-04-01
Novel fuels are part of the nationwide effort to reduce the enrichment of Uranium for energy production. Performance of such fuels is determined by irradiating their surfaces. To test irradiated samples, the instrumentation must operate remotely. The plate checker used in this experiment at Idaho National Lab (INL) performs non-destructive testing on fuel rod and plate geometries with two different types of sensors: eddy current and digital thickness gauges. The sensors measure oxide growth and total sample thickness on research fuels, respectively. Sensor measurement accuracy is crucial because even 10 microns of error is significant when determining the viability of an experimental fuel. One parameter known to affect the eddy current and thickness gauge sensors is temperature. Since both sensor accuracies depend on the ambient temperature of the system, the plate checker has been characterized for these sensitivities. The manufacturer of the digital gauge probes has noted a rather large coefficient of thermal expansion for their linear scale. It should also be noted that the accuracy of the digital gauge probes are specified at 20°C, which is approximately 7°C cooler than the average hot-cell temperature. In this work, the effect of temperature on the eddy current and digital gauge probes is studied, and thickness measurements are given as empirical functions of temperature.
Development of eddy current probe for fiber orientation assessment in carbon fiber composites
Wincheski, Russell A.; Zhao, Selina
2018-04-01
Measurement of the fiber orientation in a carbon fiber composite material is crucial in understanding the load carrying capability of the structure. As manufacturing conditions including resin flow and molding pressures can alter fiber orientation, verification of the as-designed fiber layup is necessary to ensure optimal performance of the structure. In this work, the development of an eddy current probe and data processing technique for analysis of fiber orientation in carbon fiber composites is presented. A proposed directional eddy current probe is modeled and its response to an anisotropic multi-layer conductor simulated. The modeling results are then used to finalize specifications of the eddy current probe. Experimental testing of the fabricated probe is presented for several samples including a truncated pyramid part with complex fiber orientation draped to the geometry for resin transfer molding. The inductively coupled single sided measurement enables fiber orientation characterization through the thickness of the part. The fast and cost-effective technique can be applied as a spot check or as a surface map of the fiber orientations across the structure. This paper will detail the results of the probe design, computer simulations, and experimental results.
Samoudi, Amine M.; Van Audenhaege, Karen; Vermeeren, Günter; Verhoyen, Gregory; Martens, Luc; Van Holen, Roel; Joseph, Wout
2015-10-01
Combining single photon emission computed tomography (SPECT) with magnetic resonance imaging (MRI) requires the insertion of highly conductive SPECT collimators inside the MRI scanner, resulting in an induced eddy current disturbing the combined system. We reduced the eddy currents due to the insert of a novel tungsten collimator inside transverse and longitudinal gradient coils. The collimator was produced with metal additive manufacturing, that is part of a microSPECT insert for a preclinical SPECT/MRI scanner. We characterized the induced magnetic field due to the gradient field and adapted the collimators to reduce the induced eddy currents. We modeled the x-, y-, and z-gradient coil and the different collimator designs and simulated them with FEKO, a three-dimensional method of moments / finite element methods (MoM/FEM) full-wave simulation tool. We used a time analysis approach to generate the pulsed magnetic field gradient. Simulation results show that the maximum induced field can be reduced by 50.82% in the final design bringing the maximum induced magnetic field to less than 2% of the applied gradient for all the gradient coils. The numerical model was validated with measurements and was proposed as a tool for studying the effect of a SPECT collimator within the MRI gradient coils.
Energy Technology Data Exchange (ETDEWEB)
Reboud, Ch
2006-09-15
Eddy current testing (ECT) technique is widely used in industrial fields such as iron and steel industry. Dedicated simulation tools provide a great assistance for the optimisation of ECT processes. CEA and the Vallourec Research Center have collaborated in order to develop a simulation tool of ECT of tubes. The volume integral method has been chosen for the resolution of Maxwell equations in a stratified medium, in order to get accurate results with a computation time short enough to carry out optimisation or inversion procedures. A fast model has been developed for the simulation of ECT of non magnetic tubes using specific external probes. New flaw geometries have been modelled: holes and notches with flat bottom. Validations of the developments, which have been integrated to the CIVA platform, have been carried out using experimental data recorded in laboratory conditions and in. industrial conditions, successively. The integral equations derived are solved using the Galerkin variant of the method of moments with pulse functions as projection functions. In order to overcome some memory limitations, other projection functions have been considered. A new discretization scheme based on non-uniform B-Splines of degree 1 or 2 has been implemented, which constitutes an original contribution to the existing literature. The decrease of the mesh size needed to get a given accuracy on the result may lead to the simulation of more complex ECT configurations. (author)
Effect of eddy currents in the toroidal field coils of a tokamak with an air-core transformer
International Nuclear Information System (INIS)
Tani, Keiji; Kobayashi, Tomofumi; Tamura, Sanae
1975-02-01
The effect of eddy currents in the copper parts of the toroidal field coils is evaluated for a tokamak with the air-core transformer windings located inside the bore of the toroidal field coils. By introducing appropriate weights to the solutions obtained for a simplified cylindrical model, calculation is made of the induction toroidal electric field on the plasma axis in the presence of the eddy currents. The result shows that, to reduce the influence of the eddy currents on the induction one-turn voltage to the permissible level, it is necessary to choose the optimal number of turns and shape of the single conductor of the toroidal field coil. (auth.)
Directory of Open Access Journals (Sweden)
Jialong Wu
2014-01-01
Full Text Available Aiming at the surface defect inspection of carbon fiber reinforced composite, the differential and the direct measurement finite element simulation models of pulsed eddy current flaw detection were built. The principle of differential pulsed eddy current detection was analyzed and the sensitivity of defect detection was compared through two kinds of measurements. The validity of simulation results was demonstrated by experiments. The simulation and experimental results show that the pulsed eddy current detection method based on rectangular differential probe can effectively improve the sensitivity of surface defect detection of carbon fiber reinforced composite material.
International Nuclear Information System (INIS)
Choi, S. J.; Song, M. K.; Lee, S. J.; Cho, J. W.; Sim, K. D.
2005-01-01
The High-Tc superconducting power cable consists of a multi-layer high-Tc superconducting cable core and a stabilizer which is used to bypass the current at fault time. Eddy current loss is generated in the stabilizer in normal operating condition and affects the whole system. In this paper, the eddy current losses are analyzed with respect to various structure of stabilizer by using opera-3d. Moreover, optimal conditions of the stabilizer are derived to minimize the eddy current losses from the analyzed results. The obtained results could be applied to the design and manufacture of the high-Tc superconducting power cable system.
Li, Zhao; Wang, Dazhi; Zheng, Di; Yu, Linxin
2017-10-01
Rotational permanent magnet eddy current couplers are promising devices for torque and speed transmission without any mechanical contact. In this study, flux-concentration disk-type permanent magnet eddy current couplers with double conductor rotor are investigated. Given the drawback of the accurate three-dimensional finite element method, this paper proposes a mixed two-dimensional analytical modeling approach. Based on this approach, the closed-form expressions of magnetic field, eddy current, electromagnetic force and torque for such devices are obtained. Finally, a three-dimensional finite element method is employed to validate the analytical results. Besides, a prototype is manufactured and tested for the torque-speed characteristic.
Solving the patient zero inverse problem by using generalized simulated annealing
Menin, Olavo H.; Bauch, Chris T.
2018-01-01
Identifying patient zero - the initially infected source of a given outbreak - is an important step in epidemiological investigations of both existing and emerging infectious diseases. Here, the use of the Generalized Simulated Annealing algorithm (GSA) to solve the inverse problem of finding the source of an outbreak is studied. The classical disease natural histories susceptible-infected (SI), susceptible-infected-susceptible (SIS), susceptible-infected-recovered (SIR) and susceptible-infected-recovered-susceptible (SIRS) in a regular lattice are addressed. Both the position of patient zero and its time of infection are considered unknown. The algorithm performance with respect to the generalization parameter q˜v and the fraction ρ of infected nodes for whom infection was ascertained is assessed. Numerical experiments show the algorithm is able to retrieve the epidemic source with good accuracy, even when ρ is small, but present no evidence to support that GSA performs better than its classical version. Our results suggest that simulated annealing could be a helpful tool for identifying patient zero in an outbreak where not all cases can be ascertained.
2010-10-01
... 49 Transportation 2 2010-10-01 2010-10-01 false Eddy Current Examination With Visual Inspection... PACKAGINGS Pt. 180, App. C Appendix C to Part 180—Eddy Current Examination With Visual Inspection for DOT 3AL... procedure applicable to the test equipment it uses to perform eddy current examinations. 2. Visual...
International Nuclear Information System (INIS)
Enchevich, I.B.; Barnes, M.J.; Poirier, R.L.
1991-05-01
In the perpendicular biased ferrite tuned cavity of the proposed TRIUMF Kaon Factory Booster Synchrotron, magnetizing flux passes through the cavity walls. If special care is not taken to minimize eddy current loss in the walls, the dissipated power would be excessive and the magnetic fields set up by the eddy currents would disturb the magnetic field being applied. By electrically isolating the cooling structure from the cavity walls and introducing slots in the walls it is possible to bring to an acceptable level both the power loss and the maximal temperatures. Based on the measurements, an analytical model - essentially 3D - was derived and the eddy currents were predicted using the circuit analysis program PSpice. The calculated surface current and power distribution agree with measurements. PSpice can now be used to determine the effect of design changes on the eddy current and power distribution. (Author) 7 refs., 5 figs
Liu, Tonghua; Wang, Wei; Qiang, Wenjiang; Shu, Guogang
2018-04-01
To study the thermal aging embrittlement of Z3CN20.09M duplex stainless steel produced in China, accelerated thermal aging experiments were carried out at 380 °C up to 9000 h. Microhardness measurements, Charpy impact and eddy current tests were performed on aged samples to characterize their thermal aging embrittlement. The results showed that the signal amplitude of eddy current decreased with the increase in aging time. Two quantitative correlations of the eddy current signal amplitude with both the Charpy impact energy, and the Vickers microhardness of the ferrite phase are obtained. The study showed that eddy current testing could be used to non-destructively evaluate the thermal aging embrittlement of cast duplex stainless steels.
Eddy current testing on structures of nuclear-grade IG-110 graphite for acceptance test in HTTR
International Nuclear Information System (INIS)
Ishihara, Masahiro; Saikusa, Akio; Iyoku, Tatsuo
1993-09-01
Core and core support graphite structures in the HTTR are mainly made of IG-110 graphite which is fine-grained isotropic and nuclear-grade. Nondestructive inspection with eddy current testing is planned to be applied to these graphite structures. Eddy current testing is widely applied to metallic structures and its testing method has been already established. On the other hand, the characteristics of graphite are quite different in micro-structure from these of metals. Therefore, the eddy current testing method provided for metallic structures can not be applied directly to graphite structures. Thus the eddy current testing method and condition were established for the graphite structures made of IG-110 graphite. (author)
Beckstein, Pascal; Galindo, Vladimir; Vukčević, Vuko
2017-09-01
Eddy-current problems occur in a wide range of industrial and metallurgical applications where conducting material is processed inductively. Motivated by realising coupled multi-physics simulations, we present a new method for the solution of such problems in the finite volume framework of foam-extend, an extended version of the very popular OpenFOAM software. The numerical procedure involves a semi-coupled multi-mesh approach to solve Maxwell's equations for non-magnetic materials by means of the Coulomb gauged magnetic vector potential A and the electric scalar potential ϕ. The concept is further extended on the basis of the impressed and reduced magnetic vector potential and its usage in accordance with Biot-Savart's law to achieve a very efficient overall modelling even for complex three-dimensional geometries. Moreover, we present a special discretisation scheme to account for possible discontinuities in the electrical conductivity. To complement our numerical method, an extensive validation is completing the paper, which provides insight into the behaviour and the potential of our approach.
Bennett, P. F. D.; Underhill, P. R.; Morelli, J.; Krause, T. W.
2018-04-01
Fuel channels in CANDU® (CANada Deuterium Uranium) nuclear reactors consist of two non-concentric tubes; an inner pressure tube (PT) and a larger diameter calandria tube (CT). Up to 400 horizontally mounted fuel channels are contained within a calandria vessel, which also holds the heavy water moderator. Certain fuel channels pass perpendicularly over horizontally oriented tubes (nozzles) that are part of the reactor's liquid injection shutdown system (LISS). Due to sag, these fuel channels are at risk of coming into contact with the LISS nozzles. In the event of contact between the LISS nozzle and CT, flow-induced vibrations from within the moderator could lead to fretting and deformation of the CT. LISS nozzle proximity to CTs is currently measured optically from within the calandria vessel, but from outside the fuel channels. Measurement by an independent means would provide confidence in optical results and supplement cases where optical observations are not possible. Separation of PT and CT, known as gap, is monitored from within the PT using a transmit-receive eddy current probe. Investigation of the eddy current based gap probe as a tool to also measure proximity of LISS nozzles was carried out experimentally in this work. Eddy current response as a function of LISS-PT proximity was recorded. When PT-CT gap, PT wall thickness, PT resistivity and probe lift-off variations were not present this dependence could be used to determine the LISS-PT proximity. This method has the potential to provide LISS-CT proximity using existing gap measurement data. Obtaining LISS nozzle proximity at multiple inspection intervals could be used to provide an estimate of the time to LISS-CT contact, and thereby provide a means of optimizing maintenance schedules.
International Nuclear Information System (INIS)
Vigneron, Audrey
2015-01-01
The thesis addresses the numerical simulation of non-destructive testing (NDT) using eddy currents, and more precisely the computation of induced electromagnetic fields by a transmitter sensor in a healthy part. This calculation is the first step of the modeling of a complete control process in the CIVA software platform developed at CEA LIST. Currently, models integrated in CIVA are restricted to canonical (modal computation) or axially-symmetric geometries. The need for more diverse and complex configurations requires the introduction of new numerical modeling tools. In practice the sensor may be composed of elements with different shapes and physical properties. The inspected parts are conductive and may contain dielectric or magnetic elements. Due to the cohabitation of different materials in one configuration, different regimes (static, quasi-static or dynamic) may coexist. Under the assumption of linear, isotropic and piecewise homogeneous material properties, the surface integral equation (SIE) approach allows to reduce a volume-based problem to an equivalent surface-based problem. However, the usual SIE formulations for the Maxwell's problem generally suffer from numerical noise in asymptotic situations, and especially at low frequencies. The objective of this study is to determine a version that is stable for a range of physical parameters typical of eddy-current NDT applications. In this context, a block-iterative scheme based on a physical decomposition is proposed for the computation of primary fields. This scheme is accurate and well-conditioned. An asymptotic study of the integral Maxwell's problem at low frequencies is also performed, allowing to establish the eddy-current integral problem as an asymptotic case of the corresponding Maxwell problem. (author) [fr
International Nuclear Information System (INIS)
Boffo, C.; Bauer, P.
2005-01-01
As part of the material QC process, each Niobium disk from which a superconducting RF cavity is built must undergo an eddy current scan [1]. This process allows to discover embedded defects in the material that are not visible to the naked eye because too small or under the surface. Moreover, during the production process of SC cavities the outer layer of Nb is removed via chemical or electro-chemical etching, thus it is important to evaluate the quality of the subsurface layer (in the order of 100nm) where superconductivity will happen. The reference eddy current scanning machine is operated at DESY; at Fermilab we are using the SNS eddy current scanner on loan, courtesy of SNS. In the past year, several upgrades were implemented aiming at raising the SNS machine performance to that of the DESY reference machine [2]. As part of this effort an algorithm that enables the filtering of the results of the scans and thus improves the resolution of the process was developed. The description of the algorithm and of the software used to filter the scan results is presented in this note. This filter application is a useful tool when the coupling between the signal associated to the long range probe distance (or sample thickness) variation and that associated to inclusions masks the presence of defects. Moreover instead of using indirect criteria (such as appearance on screen), the filter targets precisely the topology variations of interest. This application is listed in the FermiTools database and is freely available
Evaluation of plate type fuel elements by eddy current test method
International Nuclear Information System (INIS)
Frade, Rangel Teixeira
2015-01-01
Plate type fuel elements are used in MTR research nuclear reactors. The fuel plates are manufactured by assembling a briquette containing the fissile material inserted in a frame, with metal plates in both sides of the set, to act as a cladding. This set is rolled under controlled conditions in order to obtain the fuel plate. In Brazil, this type of fuel is manufactured by IPEN and used in the IEA-R1 reactor. After fabrication of three batches of fuel plates, 24 plates, one of them is taken, in order to verify the thickness of the cladding. For this purpose, the plate is sectioned and the thickness measurements are carried out by using optical microscopy. This procedure implies in damage of the plate, with the consequent cost. Besides, the process of sample preparation for optical microscopy analysis is time consuming, it is necessary an infrastructure for handling radioactive materials and there is a generation of radioactive residues during the process. The objective of this study was verify the applicability of eddy current test method for nondestructive measurement of cladding thickness in plate type nuclear fuels, enabling the inspection of all manufactured fuel plates. For this purpose, reference standards, representative of the cladding of the fuel plates, were manufactured using thermomechanical processing conditions similar to those used for plates manufacturing. Due to no availability of fuel plates for performing the experiments, the presence of the plate’s core was simulated using materials with different electrical conductivities, fixed to the thickness reference standards. Probes of eddy current testing were designed and manufactured. They showed high sensitivity to thickness variations, being able to separate small thickness changes. The sensitivity was higher in tests performed on the reference standards and samples without the presence of the materials simulating the core. For examination of the cladding with influence of materials simulating the
A Study of Frequency Mixing Approaches for Eddy Current Testing of Steam Generator Tubes
International Nuclear Information System (INIS)
Jung, Hee Jun; Song, Sung Jin; Kim, Chang Hwan; Kim, Dae Kwang
2009-01-01
The multifrequency eddy current testing(ECT) have been proposed various frequency mixing algorithms. In this study, we compare these approaches to frequency mixing of ECT signals from steam generator tubes; time-domain optimization, discrete cosine transform-domain optimization. Specifically, in this study, two different frequency mixing algorithms, a time-domain optimization method and a discrete cosine transform(DCT) optimization method, are investigated using the experimental signals captured from the ASME standard tube. The DCT domain optimization method is computationally fast but produces larger amount of residue.
Eddy-current flow rate meter for measuring sodium flow rates
International Nuclear Information System (INIS)
Knaak, J.
1976-01-01
For safety reasons flow rate meters for monitoring coolant flow rates are inserted in the core of sodium-cooled fast breeder reactors. These are so-called eddy-current flow rate meters which can be mounted directly above the fuel elements. In the present contribution the principle of measurement, the mechanical construction and the circuit design of the flow rate measuring device are described. Special problems and their solution on developing the measuring system are pointed out. Finally, results of measurement and experience with the apparatus in several experiments are reported, where also further possibilities of application were tested. (orig./TK) [de
Influence of sodium deposits in steam generator tubes on remote field eddy current signals
Energy Technology Data Exchange (ETDEWEB)
Thirunavukkarasu, S. [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India); Rao, B.P.C. [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)], E-mail: bpcrao@igcar.gov.in; Vaidyanathan, S.; Jayakumar, T.; Raj, Baldev [EMSI Section, NDE Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)
2008-04-15
The presence of sodium deposits in defective regions of steam generator (SG) tubes of fast-breeder reactors is expected to influence the remote field eddy current (RFEC) signals. By exposing five SG tubes having uniform wall loss grooves to a sodium environment in a specially designed test vessel, changes in the shape of RFEC signals were observed and it was possible to approximate the volume of sodium deposited in defects. An invariant signal parameter was determined for quantitative characterization of defects despite the presence of sodium in the defects.
Analysis of unbalanced sensor in eddy current method of non destructive testing
International Nuclear Information System (INIS)
Chegodaev, V.V.
2001-01-01
Different types of sensors are used in eddy current method of non-destructive testing. The choosing of sensor type depends on control object. Different types of sensors can have the same schemes of cut-in in device for formation of information signal. The most common scheme of sensor cut-in is presented. The calculation of output voltage when the sensor is on a segment of the control object, which has not defect is made. The conditions of balancing are adduced and it was shown that the balancing of sensor is very difficult. The methods of compensation or account of voltage of an imbalance are indicated. (author)
Eddy-current tests on operational evaluation of steam generator tubes in nuclear power plants
International Nuclear Information System (INIS)
Lopez, Luiz Antonio Negro Martin; Ting, Daniel Kao Sun
2000-01-01
This paper presents a worldwide research on the technical and economical impacts due to failure in tube bundles of nuclear power plant steam generators. An Eddy current non destructive test using Foucault currents for the inspection and failure detection on the tubes, and also the main type of defects. The paper also presents the signals generated by a Zetec MIZ-40 test equipment. This paper also presents a brief description of an automatic system for data analysis which is under development by using a fuzzy logic and artificial intelligence
Tube-AVB gap measurements using an eddy current rotating probe
International Nuclear Information System (INIS)
Badson, F.; Chiron, D.; Trumpff, B.
1988-01-01
The wears of tubes due to flow induced vibrations have been observed after a few years of operating PWR steam generators (SG). The vibration and wear are intimately related to the gap between tubes and anti-vibration bars (AVB's) located in the bundle. The authors report the development of an eddy current (EC) method for the measurement of this gap. The method is based on using an EC probe rotating in the tube. Since for each measurement zone the tube is interacting with two AVB's the use of a rotating EC probe is necessary to perform separate and accurate measurements of each tube-AVB gap
Eddy current automatic inspection of heat exchangers in nuclear power stations
International Nuclear Information System (INIS)
Cazal, M.; Scopelliti, J.D.; Mendez, J.
1997-01-01
This presentation describes the eddy current tube inspection techniques for heavy heat exchangers in nuclear power stations. The purpose of these eddy current tests, is first to determine the integrity of the heat exchanger tubes, and to characterize the related types of defects in each case following to their analysis and cause determination and subsequent inspection planning. This task requires a group highly qualified personnel with high tech automate equipment. The organization of the group required a correct function and task assignment in order to achieve efficiency in scheduling, with simultaneous inspection to different components in a continuous base and uninterruptedly. A lead specialist is in charge of the group, which is set up by several shift supervisors, a qualified tele manipulator installation crew a number of qualified tele manipulator operators, and the specialist for data acquisition and certified eddy current signal evaluators plus some other support technicians and administrations helpers. In order to comply with inspection requirements, a bunch of technical procedures had to be developed. The following equipment is available nowadays: Zetec SM-13, SM-23 and SM-22 tele manipulators for inspection probes positioning, with different shapes and configuration (rotating probes, flexible probes for U-Bends, and magnetic saturation probes endowed with their own driving units) and remote data acquisition units identified as MIZ-18 A and MIZ-30, which are remotely operated from a mobile lab installed in a trailer, outside the reactor building. The available equipment allows a simultaneous inspection of three different plant components (two steam generators and a moderator heat exchanger). We are also in a position of performing eddy current tube inspection in more than a NSP at the same time. The Zetec Eddynet software is used in the manipulator operation and for the data acquisition and defect evaluation. This software operates within Windows
Signal to noise ratio enhancement for Eddy Current testing of steam generator tubes in PWR's
International Nuclear Information System (INIS)
Georgel, B.
1985-01-01
Noise reduction is a compulsory task when we try to recognize and characterize flaws. The signals we deal with come from Eddy Current testings of steam generator steel tubes. We point out the need for a spectral invariant in digital spectral analysis of 2 components signals. We make clear the pros and cons of classical passband filtering and suggest the use of a new noise cancellation method first discussed by Moriwaki and Tlusty. We generalize this tricky technique and prove it is a very special case of the well-known Wiener filter. In that sense the M-T method is shown to be optimal. 6 refs
FELIX experiments and computational needs for eddy current analysis of fusion reactors
International Nuclear Information System (INIS)
Turner, L.R.
1984-01-01
In a fusion reactor, changing magnetic fields are closely coupled to the electrically-conducting metal structure. This coupling is particularly pronounced in a tokamak reactor in which magnetic fields are used to confine, stabilize, drive, and heat the plasma. Electromagnetic effects in future fusion reactors will have far-reaching implications in the configuration, operation, and maintenance of the reactors. This paper describes the impact of eddy-current effects on future reactors, the requirements of computer codes for analyzing those effects, and the FELIX experiments which will provide needed data for code validation
Study on practical of eddy current testing of core and core support graphite components in HTTR
International Nuclear Information System (INIS)
Ishihara, Masahiro; Iyoku, Tatsuo; Ooka, Norikazu; Shindo, Yoshihisa; Kawae, Hidetoshi; Hayashi, Motomitsu; Kambe, Mamoru; Takahashi, Masaaki; Ide, Akira.
1994-01-01
Core and core support graphite components in the HTTR (High Temperature Engineering Test Reactor) are mainly made of nuclear-grade IG-110 and PGX graphites. Nondestructive inspection with Eddy Current Testing (ECT) is planned to be applied to these components. The method of ECT has been already established for metallic components, however, cannot be applied directly to the graphite ones, because the characteristics of graphite are quite different in micro-structure from those of metals. Therefore, ECT method and condition were studied for the application of the ECT to the graphite components. This paper describes the study on practical method and conditions of ECT for above mentioned graphite structures. (author)
Koshti, Ajay M.
2018-03-01
Like other NDE methods, eddy current surface crack detectability is determined using probability of detection (POD) demonstration. The POD demonstration involves eddy current testing of surface crack specimens with known crack sizes. Reliably detectable flaw size, denoted by, a90/95 is determined by statistical analysis of POD test data. The surface crack specimens shall be made from a similar material with electrical conductivity close to the part conductivity. A calibration standard with electro-discharged machined (EDM) notches is typically used in eddy current testing for surface crack detection. The calibration standard conductivity shall be within +/- 15% of the part conductivity. This condition is also applicable to the POD demonstration crack set. Here, a case is considered, where conductivity of the crack specimens available for POD testing differs by more than 15% from that of the part to be inspected. Therefore, a direct POD demonstration of reliably detectable flaw size is not applicable. Additional testing is necessary to use the demonstrated POD test data. An approach to estimate the reliably detectable flaw size in eddy current testing for part made from material A using POD crack specimens made from material B with different conductivity is provided. The approach uses additional test data obtained on EDM notch specimens made from materials A and B. EDM notch test data from the two materials is used to create a transfer function between the demonstrated a90/95 size on crack specimens made of material B and the estimated a90/95 size for part made of material A. Two methods are given. For method A, a90/95 crack size for material B is given and POD data is available. Objective of method A is to determine a90/95 crack size for material A using the same relative decision threshold that was used for material B. For method B, target crack size a90/95 for material A is known. Objective is to determine decision threshold for inspecting material A.
Sensitive technique for detecting outer defect on tube with remote field eddy current testing
International Nuclear Information System (INIS)
Kobayashi, Noriyasu; Nagai, Satoshi; Ochiai, Makoto; Jimbo, Noboru; Komai, Masafumi
2008-01-01
In the remote field eddy current testing, we proposed the method of enhancing the magnetic flux density in the vicinity of an exciter coil by controlling the magnetic flux direction for increasing the sensitivity of detecting outer defects on a tube and used the flux guide made of a magnetic material for the method. The optimum structural shape of the flux guide was designed by the magnetic field analysis. On the experiment with the application of the flux guide, the magnetic flux density increased by 59% and the artificial defect detection signal became clear. We confirmed the proposed method was effective in a high sensitivity. (author)
Modeling of Eddy current distribution and equilibrium reconstruction in the SST-1 Tokamak
International Nuclear Information System (INIS)
Banerjee, Santanu; Sharma, Deepti; Radhakrishnana, Srinivasan; Daniel, Raju; Shankara Joisa, Y.; Atrey, Parveen Kumar; Pathak, Surya Kumar; Singh, Amit Kumar
2015-01-01
Toroidal continuity of the vacuum vessel and the cryostat leads to the generation of large eddy currents in these passive structures during the Ohmic phase of the steady state superconducting tokamak SST-1. This reduces the magnitude of the loop voltage seen by the plasma as also delays its buildup. During the ramping down of the Ohmic transformer current (OT), the resultant eddy currents flowing in the passive conductors play a crucial role in governing the plasma equilibrium. Amount of this eddy current and its distribution has to be accurately determined such that this can be fed to the equilibrium reconstruction code as an input. For the accurate inclusion of the effect of eddy currents in the reconstruction, the toroidally continuous conducting structures like the vacuum vessel and the cryostat with large poloidal cross-section and any other poloidal field (PF) coil sitting idle on the machine are broken up into a large number of co-axial toroidal current carrying filaments. The inductance matrix for this large set of toroidal current carrying conductors is calculated using the standard Green's function and the induced currents are evaluated for the OT waveform of each plasma discharge. Consistency of this filament model is cross-checked with the 11 in-vessel and 12 out-vessel toroidal flux loop signals in SST-1. Resistances of the filaments are adjusted to reproduce the experimental measurements of these flux loops in pure OT shots and shots with OT and vertical field (BV). Such shots are taken routinely in SST-1 without the fill gas to cross-check the consistency of the filament model. A Grad-Shafranov (GS) equation solver, named as IPREQ, has been developed in IPR to reconstruct the plasma equilibrium through searching for the best-fit current density profile. Ohmic transformer current (OT), vertical field coil current (BV), currents in the passive filaments along with the plasma pressure (p) and current (I p ) profiles are used as inputs to the IPREQ
Results of eddy current test for second round robin by Halden reactor project
International Nuclear Information System (INIS)
Iwai, Takashi; Souzawa, Shizuo; Miyata, Seiichi; Sakai, Haruyuki; Sakakura, Atsushi
1986-08-01
JMTR Hot Laboratory has executed the eddy current test of two PWR type zircaloy cladding tubes for the second round robin by Halden Reactor Project. Defects manufactured on the test specimen were revealed on a fair way to success as a function of local position, phase character and size. Influence of the fatigue crack between the two different tubes was studied through the phase angle analysis. More effort should be needed for detecting rather smaller internal defect when it was combined with external and other various type of defects. (author)
Detection and Sizing of Fatigue Cracks in Steel Welds with Advanced Eddy Current Techniques
Todorov, E. I.; Mohr, W. C.; Lozev, M. G.
2008-02-01
Butt-welded specimens were fatigued to produce cracks in the weld heat-affected zone. Advanced eddy current (AEC) techniques were used to detect and size the cracks through a coating. AEC results were compared with magnetic particle and phased-array ultrasonic techniques. Validation through destructive crack measurements was also conducted. Factors such as geometry, surface treatment, and crack tightness interfered with depth sizing. AEC inspection techniques have the potential of providing more accurate and complete sizing flaw data for manufacturing and in-service inspections.
Recent Advances in Simulation of Eddy Current Testing of Tubes and Experimental Validations
Reboud, C.; Prémel, D.; Lesselier, D.; Bisiaux, B.
2007-03-01
Eddy current testing (ECT) is widely used in iron and steel industry for the inspection of tubes during manufacturing. A collaboration between CEA and the Vallourec Research Center led to the development of new numerical functionalities dedicated to the simulation of ECT of non-magnetic tubes by external probes. The achievement of experimental validations led us to the integration of these models into the CIVA platform. Modeling approach and validation results are discussed here. A new numerical scheme is also proposed in order to improve the accuracy of the model.
International Nuclear Information System (INIS)
Chen, Zhenmao
1998-12-01
In this paper, an approach to the reconstruction of an idealized natural crack of non-vanishing conductivity is proposed with use of signals of eddy current testing. Two numerical models are introduced at first for modeling a Stress Corrosion Crack (SCC) in order it possibly to be represented by a set of crack parameters. A method for rapid prediction of the eddy current testing signals arisen from these idealized cracks is given then by extending a knowledge based fast forward solver developed by authors to the case of a non-vanishing conductivity. On the other hand, the inverse algorithm of conjugate gradient method is improved to reconstruct the crack parameters and is implemented with the pick-up signals and gradients calculated by using the rapid forward solver. Several examples are presented finally for validating the proposed strategy. The results verified that both of the models can give reasonable reconstruction results in case of a low noise level. The model concerning the touch of crack surfaces with a conducting band region surrounded by the crack edge, however, is proved more efficient that the model using a conductivity distribution from the point of view of both reconstruction speed and accuracy. (author)
Foucault pendulum with eddy-current damping of the elliptical motion
Mastner, G.; Vokurka, V.; Maschek, M.; Vogt, E.; Kaufmann, H. P.
1984-10-01
A newly designed Foucault pendulum is described in which the mechanical Charron ring, used throughout in previous designs for damping of the elliptical motion of the pendulum, is replaced by an electromagnetic eddy-current brake, consisting of a permanent magnet attached to the bottom of the bob and a metallic ring. This damping device is very efficient, as it is self-aligning, symmetrical in the damping effect, and never wears out. The permanent magnet is also used, together with a coil assembly and an electronic circuitry, for the dipole-torque drive of the pendulum as well as for accurate stabilization of the amplitude of the swing. A latched time display, controlled by Hall probes activated by the magnet, is used to visualize the Foucault rotation. The pendulum system and its associated electronic circuitry are described in detail. The optimizing of the drive mode is discussed. Measurements of deviations from theoretical value of the Foucault rotation velocity made automatically in a continuous run show a reproducible accuracy of ±1% or better in individual 360° rotations during the summer months. The quality factor of the pendulum as mechanical resonator was measured as a function of the amplitude in the presence of the eddy-current damping ring.
EddyOne automated analysis of PWR/WWER steam generator tubes eddy current data
International Nuclear Information System (INIS)
Nadinic, B.; Vanjak, Z.
2004-01-01
INETEC Institute for Nuclear Technology developed software package called Eddy One which has option of automated analysis of bobbin coil eddy current data. During its development and on site use, many valuable lessons were learned which are described in this article. In accordance with previous, the following topics are covered: General requirements for automated analysis of bobbin coil eddy current data; Main approaches to automated analysis; Multi rule algorithms for data screening; Landmark detection algorithms as prerequisite for automated analysis (threshold algorithms and algorithms based on neural network principles); Field experience with Eddy One software; Development directions (use of artificial intelligence with self learning abilities for indication detection and sizing); Automated analysis software qualification; Conclusions. Special emphasis is given on results obtained on different types of steam generators, condensers and heat exchangers. Such results are then compared with results obtained by other automated software vendors giving clear advantage to INETEC approach. It has to be pointed out that INETEC field experience was collected also on WWER steam generators what is for now unique experience.(author)
Comparison between 3D eddy current patterns in tokamak in-vessel components generated by disruptions
International Nuclear Information System (INIS)
Sakellaris, J.; Crutzen, Y.
1996-01-01
During plasma disruption events in Tokamaks, a large amount of magnetic energy is associated to the transfer of plasma current into eddy currents in the passive structures. In the ITER program two design concepts have been proposed. One approach (ITER CDA design) is based on copper stabilization loops (i.e., twin loops) attached to box-shaped blanket segments, electrically and mechanically separated along the toroidal direction. For another design concept (ITER EDA design) based on lower plasma elongation there is no need for specific stabilization loops. The passive stabilization is obtained by toroidally continuous components (i.e., the plasma facing wall of the blanket segments allows a continuity along the toroidal direction). Consequently, toroidal currents flow, when electromagnetic transients occur. Electromagnetic loads appear in the blanket structures in case of plasma disruptions and/or vertical displacement events either for the ITER CDA design concept or for the ITER EDA design concept. In this paper the influence of the in-vessel design configuration concepts--insulated segments or electrically continuous structures--in terms of magnetic shielding and electric insulation on the magnitude and the flow pattern of the eddy currents is investigated. This investigation will allow a performance evaluation of the two proposed design concepts
Model based optimization of driver-pickup separation for eddy current measurement of gap
Klein, G.; Morelli, J.; Krause, T. W.
2018-04-01
The fuel channels in CANDU® (CANada Deuterium Uranium) nuclear reactors consist of a pressure tube (PT) contained within a larger diameter calandria tube (CT). The separation between the tubes, known as the PT-CT gap, ensures PT hydride blisters, which could lead to potential cracking of the PT, do not develop. Therefore, accurate measurements are required to confirm that contact between PT and CT is not imminent. Gap measurement uses an eddy current probe. However this probe is sensitive to lift-off variations, which can adversely affect estimated gap. A validated analytical flat plate model of eddy current response to gap was used to examine the effect of driver-pickup spacing on lift-off and response to gap at a frequency of 4 kHz, which is used for in-reactor measurements. This model was compared against, and shown to have good agreement with, a COMSOL® finite element method (FEM) model. The optimum coil separation, which included the constraint of coil size, was found to be 11 mm, resulting in a phase response between lift-off and response to change in gap of 66°. This work demonstrates the advantages of using analytical models for optimizing coil designs for measurement of parameters that may negatively influence the outcome of an inspection measurement.
A new method for electric impedance imaging using an eddy current with a tetrapolar circuit.
Ahsan-Ul-Ambia; Toda, Shogo; Takemae, Tadashi; Kosugi, Yukio; Hongo, Minoru
2009-02-01
A new contactless technique for electrical impedance imaging, using an eddy current managed along with the tetrapolar circuit method, is proposed. The eddy current produced by a magnetic field is superimposed on a constant current that is normally used in the tetrapolar circuit method, and thus is used to control the current distribution in the body. By changing the current distribution, a set of voltage differences is measured with a pair of electrodes. This set of voltage differences is used in the image reconstruction of the resistivity distribution. The least square error minimization method is used in the reconstruction algorithm. The principle of this method is explained theoretically. A backprojection algorithm was used to get 2-D images. Based on this principle, a measurement system was developed and model experiments were conducted with a saline-filled phantom. The estimated shape of each model in the reconstructed image was similar to that of the corresponding model. From the results of these experiments, it is confirmed that the proposed method is applicable to the realization of electrical conductivity imaging.
Fatigue Crack Length Sizing Using a Novel Flexible Eddy Current Sensor Array
Directory of Open Access Journals (Sweden)
Ruifang Xie
2015-12-01
Full Text Available The eddy current probe, which is flexible, array typed, highly sensitive and capable of quantitative inspection is one practical requirement in nondestructive testing and also a research hotspot. A novel flexible planar eddy current sensor array for the inspection of microcrack presentation in critical parts of airplanes is developed in this paper. Both exciting and sensing coils are etched on polyimide films using a flexible printed circuit board technique, thus conforming the sensor to complex geometric structures. In order to serve the needs of condition-based maintenance (CBM, the proposed sensor array is comprised of 64 elements. Its spatial resolution is only 0.8 mm, and it is not only sensitive to shallow microcracks, but also capable of sizing the length of fatigue cracks. The details and advantages of our sensor design are introduced. The working principal and the crack responses are analyzed by finite element simulation, with which a crack length sizing algorithm is proposed. Experiments based on standard specimens are implemented to verify the validity of our simulation and the efficiency of the crack length sizing algorithm. Experimental results show that the sensor array is sensitive to microcracks, and is capable of crack length sizing with an accuracy within ±0.2 mm.
Applications of pulsed Eddy Current (PEC) technique on defect and material assessment
International Nuclear Information System (INIS)
Nurul A'in Ahmad Latif; Noorhazleena Azaman; Ilham Mukriz Zainal Abidin
2014-01-01
The pulsed eddy current (PEC) is an emerging electromagnetic method and widely used in multiple field including aerospace, petrochemical, industry and transportation. PEC mainly depends on the multiple variables such as peak value and rising time to detect and quantify the defects. Apart of its advantage as non contacting technique, it has ability on conducting surface and subsurface detection. Additionally, PEC is high sensitive to variety parameters that are inherent in the flaws. Compare to conventional eddy current, PEC allows deeper penetration as it is a combination from multiple frequencies. This paper demonstrates the abilities of PEC technique performing multiple testing in various fields such as conducting conductivity testing, measuring the material thickness and identifying depth of the defects. The conductivity testing will be performed on multiple materials such as aluminium, stainless steel, copper, austenitic steel and titanium. To measure the material thicknesses, PEC testing will be conducted on the multi layered specimen with the different thickness. Meanwhile to identify depth of defects, the testing will be carried out using a stainless steel calibration block contains multiple length of defect. For the validation purposes, all the results generate through the experiments will be compared with simulation results produced using dedicated software, COMSOL. (author)
Characterization and optimization of spiral eddy current coils for in-situ crack detection
Mandache, Catalin
2018-03-01
In-situ condition-based maintenance is making strides in the aerospace industry and it is seen as an alternative to scheduled, time-based maintenance. With fatigue cracks originating from fastener holes as the main reason for structural failures, embedded eddy current coils are a viable non-invasive solution for their timely detection. The development and potential broad use of these coils are motivated by a few consistent arguments: (i) inspection of structures of complicated geometries and hard to access areas, that often require disassembly, (ii) alternative to regular inspection actions that could introduce inadvertent damage, (iii) for structures that have short inspection intervals, and (iv) for repaired structures where fastener holes contain bushings and prevent further bolt-hole inspections. Since the spiral coils are aiming at detecting radial cracks emanating from the fastener holes, their design parameters should allow for high inductance, low ohmic losses and power requirements, as well as optimal size and high sensitivity to discontinuities. In this study, flexible, surface conformable, spiral eddy current coils are empirically investigated on mock-up specimens, while numerical analysis is performed for their optimization and design improvement.
Eddy Current Nondestructive Residual Stress Assessment in Shot-Peened Nickel-Base Superalloys
International Nuclear Information System (INIS)
Blodgett, M.P.; Yu, F.; Nagy, P.B.
2005-01-01
Shot peening and other mechanical surface enhancement methods improve the fatigue resistance and foreign-object damage tolerance of metallic components by introducing beneficial near-surface compressive residual stresses and hardening the surface. However, the fatigue life improvement gained via surface enhancement is not explicitly accounted for in current engine component life prediction models because of the lack of accurate and reliable nondestructive methods that could verify the presence of compressive near-surface residual stresses in shot-peened hardware. In light of its frequency-dependent penetration depth, the measurement of eddy current conductivity has been suggested as a possible means to allow the nondestructive evaluation of subsurface residual stresses in surface-treated components. This technique is based on the so-called piezoresistivity effect, i.e., the stress-dependence of electrical resistivity. We found that, in contrast with most other materials, surface-treated nickel-base superalloys exhibit an apparent increase in electrical conductivity at increasing inspection frequencies, i.e., at decreasing penetration depths. Experimental results are presented to illustrate that the excess frequency-dependent apparent eddy current conductivity of shot-peened nickel-base superalloys can be used to estimate the absolute level and penetration depth of the compressive residual stress layer both before and after partial thermal relaxation
MR angiography of eddy-current-free MR imaging system with a 3T permanent magnet
International Nuclear Information System (INIS)
Nishimura, H.; Watanabe, S.; Takeuchi, H.
1991-01-01
This paper reports that, the authors main purpose was to evaluate two-dimensional time flight MR angiography in the visualization of vascular structure by using an eddy-current-free 0.3-T permanent magnet MR imaging system. The authors have developed multisection acquisition technique for two-dimensional time-of-flight MR angiography with the use of velocity-compensated gradient echoes. MR angiograms were obtained with a ray-tracing algorithm of the new modified maximum intensity projection at various viewing angles. These angiograms are displayed on cathode-ray tubes in a high-speed cyclic mode to depict the front-rear relation of vessels for better recognition. With an eddy-current-free permanent magnet system, two-dimensional time-of-flight angiography could clearly depict intracranial vascular structure, cervical vessels, and vessels of the extremities with thin-section (2 or 3 mm) acquisition. A high flip angle (90 degrees) with a short TR enabled better differentiation between blood flow and stationary tissues. Stenosis of the carotids could be detected in accordance with digital subtraction angiography
Results of the new eddy current tester for steam generator applications
International Nuclear Information System (INIS)
Ribes, B.; Hernandez, J.; Barcenilla, V.
2006-01-01
As a result of the recent developing line of eddy current data acquisition systems a new product comes to the market named Teddy+. With only 4 kg of weight constitutes a great advance with regards to the equipments used for this type of inspections available in the market. This advances, have enabled, among others, to increase considerably the S/N ratio, avoid typical saturation problems in the eddy current signal, increase the inspection speed, eliminate the reference probe, detect the air/tube signal in real time, together with the possibility to integrate the tester inside the pusher thanks to its reduced size and to have integrated the mechanical systems control board as part of the tester. The software application in charge of data acquisition and analysis has been optimized making it possible a faster and efficient data access, incorporating a new tool to allow a data quality control on-line, which has accelerated the detection process of non-valid registers. The processes related with the supervision of different analysis have been automated enabling a simultaneous comparison of up to four different analysis types. At the same time the necessary tools to make the successive passes of the resolution process have been included in the analysis software according to EPRI guidelines. These innovations and improvements place the new SG inspection system from TECNATOM, as one of the most powerful and reliable existing in the market (orig.)
Eddy current examination of the nuclear fuel elements of IPR-R1 research reactor
International Nuclear Information System (INIS)
Silva, Roger F.; Frade, Rangel T.; Oliveira, Paulo F.; Silva, Marlucio A.; Silva Junior, Silverio F.
2015-01-01
Tubes of AISI 304 stainless steel as well as tubes of Aluminum 1100-F are used as cladding of the fuel elements of TRIGA MARK 1 nuclear research reactor. Usually, these tubes are periodically inspected by means of visual test and sipping test. The visual test allows the detection of changes occurred at the external fuel elements surface, such as those promoted by corrosion processes. However, this test method cannot be used for detection of internal discontinuities at the tube walls. Sipping test allows the detection of fuel elements in which the cladding has failed, but it is not able to determine the place where the discontinuity is located. In turn, eddy current testing, an electromagnetic nondestructive test method, allows the detection of discontinuities and monitoring their growth. In this paper, a study about the use of eddy current testing for detection and characterization of discontinuities in the fuel elements cladding is proposed. The study involves the development of probes able to operate in underwater inspections, the design and manufacture of reference standards and the development of a test methodology to perform the evaluations. (author)
Measurement of fatigue crack growth using low-profile eddy-current sensors
International Nuclear Information System (INIS)
Ditchburn, R.J.; Ibrahim, M.E.; Burke, S.K.
2011-01-01
Conformable spiral coils show promise as permanently mounted eddy-current sensors for the detection and monitoring of surface-breaking cracks in electrically conductive structures. Flexibility and a low profile (typically less than 0.5 mm) are key advantages that allow the sensors to be unobtrusively mounted on curved surfaces and beneath surface coatings. Furthermore, these sensors can be permanently mounted in areas that would otherwise be difficult or impossible to reach without significant disassembly. The sensors can be activated and interrogated using the same well-established electromagnetic measurement principles in eddy-current nondestructive inspection. A material test machine was used to grow through-thickness fatigue crack in a compact-tension specimen made from the aerospace-grade aluminium alloy AA2014. The growth of the crack was examined by measuring the small impedance changes of planar spiral-coil sensors attached to the specimen. The results indicate that permanently attached conformable spiral coils can be used to detect a deep crack once it has grown beneath the sensor, and then to monitor subsequent crack growth.
Multifrequency eddy current examination for surface defects detection of hot steel products
International Nuclear Information System (INIS)
Hiroshima, Tatsuo; Sakamoto, Takahide; Takahashi, Akio; Miyata, Kenichi.
1985-01-01
Multifrequency eddy current testing method using probe coils has been studied for surface defects detection in hot steel products at high temperature over the magnetic Curie point. The conventional signal processing method is not available for suppression of an undesirable signal caused by lift-off variation or unevenness in inspected surfaces, because the undesirable signal pattern is similar to a defect signal pattern. In order to suppress the undesirable signal a new dual frequency signal processing method using three phase rotators has been developed, and was applied to several hot steel inspections. The results are as follows. 1. In the rotating eddy current machine for hot steel rods, the lift-off variation signal caused by a wobble of rods or the difference between rotating center and pass center of rods can be suppressed. A long seam or crack whose depth is more than 0.5mm can be detected. 2. In the hot inspection for continuously cast slabs, the signal caused by oscillation mark whose depth is under 1 mm can be suppressed. A fine transversal crack whose depth is 2 mm can be detected. 3. In the hot inspection for round billets, the lift-off variation signal caused by oval shape can be eliminated, and a crack which is deeper than 1.5 mm can be clearly detected. The detectability of defects can be improved by the analysis of dual frequency signal pattern. (author)
Eddy current examination of the nuclear fuel elements of IPR-R1 research reactor
Energy Technology Data Exchange (ETDEWEB)
Silva, Roger F.; Frade, Rangel T.; Oliveira, Paulo F.; Silva, Marlucio A.; Silva Junior, Silverio F., E-mail: rfs@cdtn.br, E-mail: rtf@cdtn.br, E-mail: pfo@cdtn.br, E-mail: mas@cdtn.br, E-mail: silvasf@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
2015-07-01
Tubes of AISI 304 stainless steel as well as tubes of Aluminum 1100-F are used as cladding of the fuel elements of TRIGA MARK 1 nuclear research reactor. Usually, these tubes are periodically inspected by means of visual test and sipping test. The visual test allows the detection of changes occurred at the external fuel elements surface, such as those promoted by corrosion processes. However, this test method cannot be used for detection of internal discontinuities at the tube walls. Sipping test allows the detection of fuel elements in which the cladding has failed, but it is not able to determine the place where the discontinuity is located. In turn, eddy current testing, an electromagnetic nondestructive test method, allows the detection of discontinuities and monitoring their growth. In this paper, a study about the use of eddy current testing for detection and characterization of discontinuities in the fuel elements cladding is proposed. The study involves the development of probes able to operate in underwater inspections, the design and manufacture of reference standards and the development of a test methodology to perform the evaluations. (author)
Angular approach combined to mechanical model for tool breakage detection by eddy current sensors
Ritou, M.; Garnier, S.; Furet, B.; Hascoet, J. Y.
2014-02-01
The paper presents a new complete approach for Tool Condition Monitoring (TCM) in milling. The aim is the early detection of small damages so that catastrophic tool failures are prevented. A versatile in-process monitoring system is introduced for reliability concerns. The tool condition is determined by estimates of the radial eccentricity of the teeth. An adequate criterion is proposed combining mechanical model of milling and angular approach.Then, a new solution is proposed for the estimate of cutting force using eddy current sensors implemented close to spindle nose. Signals are analysed in the angular domain, notably by synchronous averaging technique. Phase shifts induced by changes of machining direction are compensated. Results are compared with cutting forces measured with a dynamometer table.The proposed method is implemented in an industrial case of pocket machining operation. One of the cutting edges has been slightly damaged during the machining, as shown by a direct measurement of the tool. A control chart is established with the estimates of cutter eccentricity obtained during the machining from the eddy current sensors signals. Efficiency and reliability of the method is demonstrated by a successful detection of the damage.
Analytical model of tilted driver–pickup coils for eddy current nondestructive evaluation
Cao, Bing-Hua; Li, Chao; Fan, Meng-Bao; Ye, Bo; Tian, Gui-Yun
2018-03-01
A driver-pickup probe possesses better sensitivity and flexibility due to individual optimization of a coil. It is frequently observed in an eddy current (EC) array probe. In this work, a tilted non-coaxial driver-pickup probe above a multilayered conducting plate is analytically modeled with spatial transformation for eddy current nondestructive evaluation. Basically, the core of the formulation is to obtain the projection of magnetic vector potential (MVP) from the driver coil onto the vector along the tilted pickup coil, which is divided into two key steps. The first step is to make a projection of MVP along the pickup coil onto a horizontal plane, and the second one is to build the relationship between the projected MVP and the MVP along the driver coil. Afterwards, an analytical model for the case of a layered plate is established with the reflection and transmission theory of electromagnetic fields. The calculated values from the resulting model indicate good agreement with those from the finite element model (FEM) and experiments, which validates the developed analytical model. Project supported by the National Natural Science Foundation of China (Grant Nos. 61701500, 51677187, and 51465024).
An eddy current-induced magnetic plucking for piezoelectric energy harvesting
International Nuclear Information System (INIS)
Do, Nam Ho; Baek, Yoon Su
2016-01-01
Frequency up-conversion is a very efficient method of energy harvesting in order to overcome low, non-periodic, or altered ambient vibration. In order to perform frequency up-conversion and transference of mechanical energy without contact, an eddy current-induced magnetic drag force is used. In this paper, we present a novel configuration of eddy current-induced magnetic plucking for piezoelectric energy harvesting. Our method consists of two permanent magnets, a piezoelectric beam, and a copper disk piece. We design our harvesting method to achieve loading, sudden release, and free vibration using the actuation of the piezoelectric beam through the magnetic mutual coupling between the magnet and copper disk piece. We present the principle of magnetic drag force-generation, characterize the energy harvesting performance of our harvesting method, and demonstrate our harvesting method’s capability of frequency up-conversion and transference of mechanical energy without contact under low, non-periodic, or altered ambient vibration. To that end, we describe the calculation of magnetic drag force with various geometric dimensions and material properties, model of the piezoelectric cantilever beam, comparison between estimation response and measured experiment response, and the measured voltage and power responses. (paper)
Eddy current testing for blade edge micro cracks of aircraft engine
Zhang, Wei-min; Xu, Min-dong; Gao, Xuan-yi; Jin, Xin; Qin, Feng
2017-10-01
Based on the problems of low detection efficiency in the micro cracks detection of aircraft engine blades, a differential excitation eddy current testing system was designed and developed. The function and the working principle of the system were described, the problems which contained the manufacture method of simulated cracks, signal generating, signal processing and the signal display method were described. The detection test was carried out by taking a certain model aircraft engine blade with simulated cracks as a tested specimen. The test data was processed by digital low-pass filter in the computer and the crack signals of time domain display and Lissajous figure display were acquired. By comparing the test results, it is verified that Lissajous figure display shows better performance compared to time domain display when the crack angle is small. The test results show that the eddy current testing system designed in this paper is feasible to detect the micro cracks on the aeroengine blade and can effectively improve the detection efficiency of micro cracks in the practical detection work.
Directory of Open Access Journals (Sweden)
Marc H. V. Van Regenmortel
2018-01-01
Full Text Available Hypotheses and theories are essential constituents of the scientific method. Many vaccinologists are unaware that the problems they try to solve are mostly inverse problems that consist in imagining what could bring about a desired outcome. An inverse problem starts with the result and tries to guess what are the multiple causes that could have produced it. Compared to the usual direct scientific problems that start with the causes and derive or calculate the results using deductive reasoning and known mechanisms, solving an inverse problem uses a less reliable inductive approach and requires the development of a theoretical model that may have different solutions or none at all. Unsuccessful attempts to solve inverse problems in HIV vaccinology by reductionist methods, systems biology and structure-based reverse vaccinology are described. The popular strategy known as rational vaccine design is unable to solve the multiple inverse problems faced by HIV vaccine developers. The term “rational” is derived from “rational drug design” which uses the 3D structure of a biological target for designing molecules that will selectively bind to it and inhibit its biological activity. In vaccine design, however, the word “rational” simply means that the investigator is concentrating on parts of the system for which molecular information is available. The economist and Nobel laureate Herbert Simon introduced the concept of “bounded rationality” to explain why the complexity of the world economic system makes it impossible, for instance, to predict an event like the financial crash of 2007–2008. Humans always operate under unavoidable constraints such as insufficient information, a limited capacity to process huge amounts of data and a limited amount of time available to reach a decision. Such limitations always prevent us from achieving the complete understanding and optimization of a complex system that would be needed to achieve a truly
Solving inverse problems of mathematical physics by means of the PHOENICS software package
Energy Technology Data Exchange (ETDEWEB)
Matsevity, Y; Lushpenko, S [Institute for Problems in Machinery, National Academy of Sciences of Ukraine Pozharskogo, Kharkov (Ukraine)
1998-12-31
Several approaches on organizing solution of inverse problems by means of PHOENICS on the basis of the technique of automated fitting are proposing. A version of a `nondestructive` method of using PHOENICS in the inverse problem solution regime and the ways of altering the program in the case of introducing optimization facilities in it are under consideration. (author) 12 refs.
Solving inverse problems of mathematical physics by means of the PHOENICS software package
Energy Technology Data Exchange (ETDEWEB)
Matsevity, Y.; Lushpenko, S. [Institute for Problems in Machinery, National Academy of Sciences of Ukraine Pozharskogo, Kharkov (Ukraine)
1997-12-31
Several approaches on organizing solution of inverse problems by means of PHOENICS on the basis of the technique of automated fitting are proposing. A version of a `nondestructive` method of using PHOENICS in the inverse problem solution regime and the ways of altering the program in the case of introducing optimization facilities in it are under consideration. (author) 12 refs.
Remote Field Eddy Current Probes for the Detection of Stress Corrosion in Transmission Pipelines
Energy Technology Data Exchange (ETDEWEB)
Ivanov, Plamen Alexandroz [Iowa State Univ., Ames, IA (United States)
2002-01-01
Magnetic flux leakage (MFL) is a technique used widely in non-destructive testing (NDT) of natural gas and petroleum transmission pipelines. This inspection method relies on magnetizing the pipe-wall in axial direction. The MFL inspection tool is equipped with an array of Hall sensors located around the circumference of the pipe, which registers the flux leakage caused by any defects present in the pipe-wall. Currently, the tool magnetizes the pipewall in axial direction making it largely insensitive to axially oriented defects. One type of defect, which is of a growing concern in the gas and petroleum industry is the stress corrosion crack (SCC). The SCCs are a result of aging, corrosion, fatigue and thermal stresses. SCCs are predominantly axially oriented and are extremely tight, which makes them impossible to be detected using current inspection technology. A possible solution to this problem is to utilize the remote field eddy current (RFEC) effect to detect axially oriented defects. The RFEC method has been widely used in industry in the inspection of tubular products. The method uses a pair of excitation and pick-up coils. The pick-up coil located in the remote field region, usually two, three pipe-diameters away from the excitation coil. With RFEC the presence of defects is detected by the disturbance in the phase of the signal measured by the pick-up coil relative to that of the excitation coil. Unlike conventional eddy current testing the RFEC method is sensitive to defects on the exterior of the inspected product, which makes it a good candidate for the development of in-line inspection technology. This work focuses on the development of non-destructive testing technique, which uses remote field eddy currents induced by rotating magnetic field (RMF). A major advantage of the RMF is that it makes possible to not only detect a defect but also localize its position in circumferential direction. Also, it could potentially allow detection of defects
De Geeter, Nele; Crevecoeur, Guillaume; Dupre, Luc
2011-02-01
In many important bioelectromagnetic problem settings, eddy-current simulations are required. Examples are the reduction of eddy-current artifacts in magnetic resonance imaging and techniques, whereby the eddy currents interact with the biological system, like the alteration of the neurophysiology due to transcranial magnetic stimulation (TMS). TMS has become an important tool for the diagnosis and treatment of neurological diseases and psychiatric disorders. A widely applied method for simulating the eddy currents is the impedance method (IM). However, this method has to contend with an ill conditioned problem and consequently a long convergence time. When dealing with optimal design problems and sensitivity control, the convergence rate becomes even more crucial since the eddy-current solver needs to be evaluated in an iterative loop. Therefore, we introduce an independent IM (IIM), which improves the conditionality and speeds up the numerical convergence. This paper shows how IIM is based on IM and what are the advantages. Moreover, the method is applied to the efficient simulation of TMS. The proposed IIM achieves superior convergence properties with high time efficiency, compared to the traditional IM and is therefore a useful tool for accurate and fast TMS simulations.
Chen, Tao; He, Yuting; Du, Jinqiang
2018-06-01
This paper develops a high-sensitivity flexible eddy current array (HS-FECA) sensor for crack monitoring of welded structures under varying environment. Firstly, effects of stress, temperature and crack on output signals of the traditional flexible eddy current array (FECA) sensor were investigated by experiments that show both stress and temperature have great influences on the crack monitoring performance of the sensor. A 3-D finite element model was established using Comsol AC/DC module to analyze the perturbation effects of crack on eddy currents and output signals of the sensor, which showed perturbation effect of cracks on eddy currents is reduced by the current loop when crack propagates. Then, the HS-FECA sensor was proposed to boost the sensitivity to cracks. Simulation results show that perturbation effect of cracks on eddy currents excited by the HS-FECA sensor gradually grows stronger when the crack propagates, resulting in much higher sensitivity to cracks. Experimental result further shows that the sensitivity of the new sensor is at least 19 times that of the original one. In addition, both stress and temperature variations have little effect on signals of the new sensor.
Suzuki, Masao; Aiba, Masayuki; Takahashi, Noriyuki; Ota, Satoru; Okada, Shigenori
In a magnetically levitated transportation (MAGLEV) system, a huge number of ground coils will be required because they must be laid for the whole line. Therefore, stable performance and reduced cost are essential requirements for the ground coil development. On the other hand, because the magnetic field changes when the superconducting magnet passes by, an eddy current will be generated in the conductor of the ground coil and will result in energy loss. The loss not only increases the magnetic resistance for the train running but also brings an increase in the ground coil temperature. Therefore, the reduction of the eddy current loss is extremely important. This study examined ground coils in which both the eddy current loss and temperature increase were small. Furthermore, quantitative comparison for the eddy current loss of various magnet wire samples was performed by bench test. On the basis of the comparison, a round twisted wire having low eddy current loss was selected as an effective ground coil material. In addition, the ground coils were manufactured on trial. A favorable outlook to improve the size accuracy of the winding coil and uneven thickness of molded resin was obtained without reducing the insulation strength between the coil layers by applying a compression molding after winding.
Nondestructive examination of irradiated fuel rods by pulsed eddy current techniques
International Nuclear Information System (INIS)
Francis, W.C.; Quapp, W.J.; Martin, M.R.; Gibson, G.W.
1976-02-01
A number of fuel rods and unfueled zircaloy cladding tubes which had been irradiated in the Saxton reactor have undergone extensive nondestructive and corroborative destructive examinations by Aerojet Nuclear Company as part of the Water Reactor Safety Research Program, Irradiation Effects Test Series. This report discusses the pulsed eddy current (PEC) nondestructive examinations on the fuel rods and tubing and the metallography results on two fuel rods and one irradiated zircaloy tube. The PEC equipment, designed jointly by Argonne National Laboratory and Aerojet, performed very satisfactorily the functions of diameter, profile, and wall thickness measurements and OD and ID surface defect detection. The destructive examination provided reasonably good confirmation of ''defects'' detected in the nondestructive examination
International Nuclear Information System (INIS)
Trowbridge, C.W.
1976-06-01
Various integral equation methods are described. For magnetostatic problems three formulations are considered in detail, (a) the direct solution method for the magnetisation distribution in permeable materials, (b) a method based on a scalar potential and (c) the use of an integral equation derived from Green's Theorem, i.e. the so-called Boundary Integral Method (BIM). In the case of (a) results are given for two-and three-dimensional non-linear problems with comparisons against measurement. For methods (b) and (c) which both lead to a more economic use of the computer than (a) some preliminary results are given for simple cases. For eddy current problems various methods are discussed and some results are given from a computer program based on a vector potential formulation. (author)
Quantitative Evaluation of Defect in Stainless Steel 304 Tube Using Pulsed Eddy Current Technique
International Nuclear Information System (INIS)
Nurul Ain Ahmad Latif; Ilham Mukriz Zainal Abidin; Nurul Ain Ahmad Latif; Nordin Jamaludin; Zaredah Hashim; Norhayati Ramli
2016-01-01
Pulsed eddy current (PEC) is an advanced non-destructive testing (NDT) technique that operates based on electromagnetic principle. The excitation consists of broad frequency spectrum leading to be a potential in detecting defects that are deeply buried inside the specimen. In this paper, the experiment and simulation were conducted on stainless steel plate 304 fabricated with open surface defects having a different defect depth as an investigation towards the correlation between extracted signal feature and defect depth. Two common features; time to peak and peak value that corresponds to the location depth of defect and size of defect were used for signals analysis and evaluation. The results that acquired through finite element method (FEM) simulation were compared with experimental results for the signals evaluation and defect quantification. (author)
Application of eddy currents to the inspection of fatigue-corroded railway axles
International Nuclear Information System (INIS)
Carboni, Michele
2012-01-01
Recent experience with existing railway axles indicates that even when they are operated within the design loads, failure can happen due to the synergetic effect of both corrosion and cyclic loads. This synergy is not yet thoroughly understood, however a need for detecting corrosion-fatigue during service is mandatory. In the present paper, corrosion-fatigue tests are carried out, in the lab, on small-scale specimens in order to investigate the possibility to apply eddy currents non-destructive inspection to the detection of corrosion pits and corrosion-fatigue cracks during the service of railway axles. The obtained results are also supported by suitable numerical simulations carried out by a dedicated software package. Part of the presented results were obtained in the frame of the international research project RSSB T728 (just concluded) and the European research project WOLAXIM (still in progress).
Eddy-current testing of nuclear fuel cladding tubes using tilted encircling coil system, 1
International Nuclear Information System (INIS)
Yin, Renzhong; Sekine, Kazuyoshi; Shimizu, Hisaji; Tsukui, Kazushige; Urata, Megumu.
1989-01-01
The eddy current testing method with external encircling-coils has been widely used as a standard technique for inspection of defects in irradiated zircaloy cladding tubes. In this inspection, the systematic procedure to reliably characterize defects is required. This paper describes the newly developed external tilted encircling-coil system, in which the coil axis is inclined by an angle α to the sample tube axis, for reliable determination of the sort, location and size of defects. As the results of experimental work concerning some kinds of artificial defects in zircaloy cladding tubes using newly designed tilted coil system, an adaptable general-procedure for characterization of defects has been proposed. Furthermore, it has been confirmed that in the case of smaller tilt angles of coil, the signal-to noise ratio for defect response in this coil system is approximately equal to that of ordinary encircling coil system. (author)
Energy Technology Data Exchange (ETDEWEB)
Kreutzbruck, M. v.; Allweins, K.; Heiden, C. [Giessen Univ. (Germany)
2000-07-01
The eddy current testing system described uses Foerster probes for low-frequency magnetic field detection. The major objective is to detect deep flaws in specimens/materials with good conductivity, such as aluminum. Deep flaws could be reliably detected using low excitation frequencies of a few 100 Hz and an evaluation software and data acquisition hardware matching the high dynamics of the Foerster probe. (orig./CB) [German] Es wurde ein Wirbelstromsystem auf der Basis von Foerstersonden zur niederfrequenten Magnetfelddetektion aufgebaut. Das Hauptaugenmerk hierbei lag auf der Detektion von tiefliegenden Fehlerstrukturen in gut leitfaehigen Pruefteilen, wie Aluminiumstrukturen. In Kombination mit einer an den hohen Dynamik bereich einer Foerstersonde angepassten Auswerteelektronik und Datenaufnahme konnten mittels niedrigen Anregungsfrequenzen von wenigen 100 Hz tiefliegende Fehlerstrukturen zuverlaessig detektiert werden. (orig.)
Performance demonstration tests for eddy current inspection of steam generator tubing
International Nuclear Information System (INIS)
Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.
1996-05-01
This report describes the methodology and results for development of performance demonstration tests for eddy current (ET) inspection of steam generator tubes. Statistical test design principles were used to develop the performance demonstration tests. Thresholds on ET system inspection performance were selected to ensure that field inspection systems would have a high probability of detecting and and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented in detail. Statistical test design calculations for probability of detection and flaw sizing tests are described. A recommended performance demonstration test based on the design calculations is presented. A computer program for grading the probability of detection portion of the performance demonstration test is given
Directory of Open Access Journals (Sweden)
M. S. MANNA
2011-12-01
Full Text Available The development of electromagnetic devices as machines, transformers, heating devices confronts the engineers with several problems. For the design of an optimized geometry and the prediction of the operational behaviour an accurate knowledge of the dependencies of the field quantities inside the magnetic circuits is necessary. This paper provides the eddy current and core flux density distribution analysis in linear induction motor. Magnetic flux in the air gap of the Linear Induction Motor (LIM is reduced to various losses such as end effects, fringes, effect, skin effects etc. The finite element based software package COMSOL Multiphysics Inc. USA is used to get the reliable and accurate computational results for optimization the performance of Linear Induction Motor (LIM. The geometrical characteristics of LIM are varied to find the optimal point of thrust and minimum flux leakage during static and dynamic conditions.
Continuum Modeling of Inductor Hysteresis and Eddy Current Loss Effects in Resonant Circuits
Energy Technology Data Exchange (ETDEWEB)
Pries, Jason L. [ORNL; Tang, Lixin [ORNL; Burress, Timothy A. [ORNL
2017-10-01
This paper presents experimental validation of a high-fidelity toroid inductor modeling technique. The aim of this research is to accurately model the instantaneous magnetization state and core losses in ferromagnetic materials. Quasi–static hysteresis effects are captured using a Preisach model. Eddy currents are included by coupling the associated quasi-static Everett function to a simple finite element model representing the inductor cross sectional area. The modeling technique is validated against the nonlinear frequency response from two different series RLC resonant circuits using inductors made of electrical steel and soft ferrite. The method is shown to accurately model shifts in resonant frequency and quality factor. The technique also successfully predicts a discontinuity in the frequency response of the ferrite inductor resonant circuit.
Experimental study on flaw detectability of remote field eddy current testing
International Nuclear Information System (INIS)
Kamimura, T.; Fukui, S.; Iwahashi, Y.; Yamada, H.
1988-01-01
For the purpose of comprehending the effect in practical use of the remote field eddy current (RFEC) testing that becomes noticeable for the ISI technique of steel tubes, its flaw detectability was clarified through a model test. This study used straight and bending tubes of 3.8 mm in wall thickness and 31.8 mm in outside diameter. These tubes were inspected from their inside. After relations among the pickup coil output, coil distance, testing frequency, etc. were measured, a probe of the practical use type was manufactured to investigate its flaw detectability by means of simulated flaws. The authors discuss how it has been found that light local wall thinning on the outside surfaces can be detected by this technique and its effect in practical use can be expected with small influences due to magnetic permeability variations of tube materials, bending of tubes, etc
Eddy-current inspection of ferromagnetic tubing using pulsed magnetic saturation
Energy Technology Data Exchange (ETDEWEB)
Dodd, C V; Deeds, W E
1986-07-01
A pulsed eddy-current system has been designed and developed for nondestructive evaluation of 2.25Cr-1Mo steam generator tubing from the bore side. Since the tubing is ferromagnetic, a large current pulse is sent through a driver coil to produce magnetic saturation all the way through the tube wall. A pickup coil produces an output pulse that is dependent upon the tube properties as well as the driving pulse. The output pulse heights at selected times are used as data that are computer-correlated with calibration data taken from machined standards. Performance data, circuit diagrams, and computer programs are given for the system, which has been demonstrated to detect small flaws located near the outside of a thick ferromagnetic tube.
Quantitative estimation of defects from measurement obtained by remote field eddy current inspection
International Nuclear Information System (INIS)
Davoust, M.E.; Fleury, G.
1999-01-01
Remote field eddy current technique is used for dimensioning grooves that may occurs in ferromagnetic pipes. This paper proposes a method to estimate the depth and the length of corrosion grooves from measurement of a pick-up coil signal phase at different positions close to the defect. Grooves dimensioning needs the knowledge of the physical relation between measurements and defect dimensions. So, finite element calculations are performed to obtain a parametric algebraic function of the physical phenomena. By means of this model and a previously defined general approach, an estimate of groove size may be given. In this approach, algebraic function parameters and groove dimensions are linked through a polynomial function. In order to validate this estimation procedure, a statistical study has been performed. The approach is proved to be suitable for real measurements. (authors)
Performance demonstration tests for eddy current inspection of steam generator tubing
Energy Technology Data Exchange (ETDEWEB)
Kurtz, R.J.; Heasler, P.G.; Anderson, C.M.
1996-05-01
This report describes the methodology and results for development of performance demonstration tests for eddy current (ET) inspection of steam generator tubes. Statistical test design principles were used to develop the performance demonstration tests. Thresholds on ET system inspection performance were selected to ensure that field inspection systems would have a high probability of detecting and and correctly sizing tube degradation. The technical basis for the ET system performance thresholds is presented in detail. Statistical test design calculations for probability of detection and flaw sizing tests are described. A recommended performance demonstration test based on the design calculations is presented. A computer program for grading the probability of detection portion of the performance demonstration test is given.
Interaction of a Bose–Einstein condensate and a superconductor via eddy currents
International Nuclear Information System (INIS)
Sapina, Igor; Dahm, Thomas
2013-01-01
We study center-of-mass oscillations of a dipolar Bose–Einstein condensate in the vicinity of a superconducting surface. We show that the magnetic field of the magnetic dipoles induces eddy currents in the superconductor, which act back on the Bose–Einstein condensate. This leads to a shift of its oscillation frequency and to an anharmonic coupling of the Bose–Einstein condensate with the superconductor. The anharmonicity creates a coupling to one of the collective modes of the condensate that can be resonantly enhanced if the parameters of the condensate are chosen properly. This provides a new physical mechanism to couple a Bose–Einstein condensate and a superconductor, which becomes significant for 52 Cr, 168 Er or 164 Dy condensates in superconducting microtraps. (paper)
Energy Technology Data Exchange (ETDEWEB)
Trowbridge, C W
1976-06-01
Various integral equation methods are described. For magnetostatic problems three formulations are considered in detail, (a) the direct solution method for the magnetisation distribution in permeable materials, (b) a method based on a scalar potential, and (c) the use of an integral equation derived from Green's Theorem, i.e. the so-called Boundary Integral Method (BIM). In the case of (a) results are given for two-and three-dimensional non-linear problems with comparisons against measurement. For methods (b) and (c), which both lead to a more economical use of the computer than (a), some preliminary results are given for simple cases. For eddy current problems various methods are discussed and some results are given from a computer program based on a vector potential formulation.
Designing a highly sensitive Eddy current sensor for evaluating damage on thermal barrier coating
Energy Technology Data Exchange (ETDEWEB)
Kim, Jong Min; Kim, Hak Joon; Song, Sung Jin; Seok, Chang Seong; Lee, Yeong Ze [Dept. of Mechanical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of); Lee, Seul Gi [LG Electronics, Seoul (Korea, Republic of)
2016-06-15
A thermal barrier coating (TBC) has been widely applied to machine components working under high temperature as a thermal insulator owing to its critical financial and safety benefits to the industry. However, the nondestructive evaluation of TBC damage is not easy since sensing of the microscopic change that occurs on the TBC is required during an evaluation. We designed an eddy current probe for evaluating damage on a TBC based on the finite element method (FEM) and validated its performance through an experiment. An FEM analysis predicted the sensitivity of the probe, showing that impedance change increases as the TBC thermally degrades. In addition, the effect of the magnetic shield concentrating magnetic flux density was also observed. Finally, experimental validation showed good agreement with the simulation result.
Validation Test Results for Orthogonal Probe Eddy Current Thruster Inspection System
Wincheski, Russell A.
2007-01-01
Recent nondestructive evaluation efforts within NASA have focused on an inspection system for the detection of intergranular cracking originating in the relief radius of Primary Reaction Control System (PCRS) Thrusters. Of particular concern is deep cracking in this area which could lead to combustion leakage in the event of through wall cracking from the relief radius into an acoustic cavity of the combustion chamber. In order to reliably detect such defects while ensuring minimal false positives during inspection, the Orthogonal Probe Eddy Current (OPEC) system has been developed and an extensive validation study performed. This report describes the validation procedure, sample set, and inspection results as well as comparing validation flaws with the response from naturally occuring damage.
Directory of Open Access Journals (Sweden)
T. Aly Saandy
2015-08-01
Full Text Available Abstract This article presents to an analytical calculation methodology of the Steinmetz coefficient applied to the prediction of Eddy current loss in a single-phase transformer. Based on the electrical circuit theory the active power consumed by the core is expressed analytically in function of the electrical parameters as resistivity and the geometrical dimensions of the core. The proposed modeling approach is established with the duality parallel series. The required coefficient is identified from the empirical Steinmetz data based on the experimented active power expression. To verify the relevance of the model validations both by simulations with two in two different frequencies and measurements were carried out. The obtained results are in good agreement with the theoretical approach and the practical results.
International Nuclear Information System (INIS)
Park, Duckgun; Kishore, M. B.; Lee, D. H.
2013-01-01
The test sample is a ferromagnetic carbon steel pipe having different thickness, covered with a 10 cm plastic insulation laminated by 0.4 mm Al plate to simulate the pipelines in NPPs. The PEC Probe used for the wall thinning detection consists of an excitation coil and a Hall sensor. The excitation coils in the probe is driven by a rectangular bipolar current pulse and the Hall-sensor will detects the resultant field. The Hall sensor output is considered as PEC signal. Results shows that the PEC system can detect wall thinning in an insulated pipeline of the NPPs. Local wall thinning in pipelines affects the structural integrity of industries like nuclear power plants (NPPs). In the present study a pulsed eddy current (PEC) technology to detect the wall thing of carbon steel pipe covered with insulation is developed
International Nuclear Information System (INIS)
Shin, Young Kil; Choi, Dong Myung
2007-01-01
By using numerical analysis methods, through transmission type pulsed eddy current (PEC) testing is modeled and PEC signal responses due to varying material conductivity, permeability, thickness, lift-off and pulse width are investigated. Results show that the peak amplitude of PEC signal gets reduced and the time to reach the peak amplitude is increased as the material conductivity, permeability, and specimen thickness increase. Also, they indicate that the pulse width needs to be shorter when evaluating the material conductivity and the plate thickness using the peak amplitude, and when the pulse width is long, the peak time is found to be more useful. Other results related to lift-off variation are reported as well
International Nuclear Information System (INIS)
Sharma, B.S.V.G.; Shyam, T.V.; Shrivastava, A.K.; Sinha, R.K.
1997-01-01
To extend the life of coolant channels of operating Indian Pressurised Heavy Water Reactors (PHWRs) of an early generation, repositioning of dislocated Garter Spring (GS) spacers is necessary. For this purpose a remotely operated system named INtegrated Garter spring REpositioning System (INGRES) has been developed. As a part of this system, eddy current transducers namely Garter Spring Detection Probe (GSDP) and Concentricity Detection Probe (CDP) along with respective signal processor units have been designed and developed. These devices detect GS spacers and eccentricity between Pressure Tube (PT) and Calandria Tube (CT) of the channel respectively. During a recent campaign of INGRES at Madras Atomic Power Station unit-2 (MAPS-2), these transducer systems have fulfilled intended design and operational objectives besides providing additional information regarding channel. These aspects are discussed. (author). 6 figs
Applicability evaluation of eddy current testing for underwater laser beam welding
International Nuclear Information System (INIS)
Kobayashi, Noriyasu; Kasuya, Takashi; Ueno, Souichi; Ochiai, Makoto; Yuguchi, Yasuhiro
2010-01-01
We clarified a defect detecting capability of eddy current testing (ECT) as a surface inspection technique for underwater laser beam welding. An underwater laser beam welding procedure includes groove caving as a preparation, laser beam welding in groove and welding surface grinding as a post treatment. Therefore groove and grinded welding surface inspections are required underwater. We curried out defect detection tests using three kinds of specimens simulated a groove, reactor vessel nozzle dissimilar metal welding materials and a laser beam welding material with a cross coil ECT probe. From experimental results, we confirmed that it is possible to detect 0.3 mm or more depth electro-discharge machining slits on machining surfaces in all specimens and an ECT has possibility as a surface inspection technique for underwater laser beam welding. (author)
Evaluation of the inner wall axial cracks of steam generator tubes by eddy current test
International Nuclear Information System (INIS)
Hur, Do Haeng; Choi, Myung Sik; Lee, Doek Hyun; Han, Jung Ho
2001-01-01
For the enhancement of ECT reliability on the primary water stress corrosion cracks of nuclear steam generator tubes, it is important to comprehend the signal characteristics on crack morphology and to select an appropriate probe type. In this paper, the sizing accuracy and the detectability for the inner wall axial cracks of tubes were quantitatively evaluated using the electric discharge machined notches and the corrosion cracks which were developed on the operating steam generator tubes. The difference of eddy current signal characteristics between pancake and axial coil were also investigated. The results obtained from this study provide a useful information for more precise evaluation on the inner wall axial cracks of steam generator tubes.
Measurement of the depth of narrow slotted sections in eddy current reference standards
Kim, Young-Joo; Kim, Young-gil; Ahn, Bongyoung; Yoon, Dong-Jin
2007-02-01
The dimensions of the slots in eddy current (EC) reference standards are too narrow to be measured by general depth measurement methods such as the optical (laser) or stylus methods. However, measurement of the dimensions of the machined slots is a prerequisite to using the blocks as references. The present paper suggests a measurement method for the slotted section using an ultrasonic test. The width and depth of the slots measured in our study are roughly 0.1 mm and 0.5 mm, respectively. The time of flight (TOF) of the ultrasonic wave was measured precisely. The ultrasonic velocity in the material of the EC reference standard was calculated with the measured values of the TOF and its thickness. Reflected waves from the tip of the slot and the bottom surface of the EC standard were successfully classified. Using this method we have successfully determined the depth of the slotted section.
Precise on-machine extraction of the surface normal vector using an eddy current sensor array
International Nuclear Information System (INIS)
Wang, Yongqing; Lian, Meng; Liu, Haibo; Ying, Yangwei; Sheng, Xianjun
2016-01-01
To satisfy the requirements of on-machine measurement of the surface normal during complex surface manufacturing, a highly robust normal vector extraction method using an Eddy current (EC) displacement sensor array is developed, the output of which is almost unaffected by surface brightness, machining coolant and environmental noise. A precise normal vector extraction model based on a triangular-distributed EC sensor array is first established. Calibration of the effects of object surface inclination and coupling interference on measurement results, and the relative position of EC sensors, is involved. A novel apparatus employing three EC sensors and a force transducer was designed, which can be easily integrated into the computer numerical control (CNC) machine tool spindle and/or robot terminal execution. Finally, to test the validity and practicability of the proposed method, typical experiments were conducted with specified testing pieces using the developed approach and system, such as an inclined plane and cylindrical and spherical surfaces. (paper)
Precise on-machine extraction of the surface normal vector using an eddy current sensor array
Wang, Yongqing; Lian, Meng; Liu, Haibo; Ying, Yangwei; Sheng, Xianjun
2016-11-01
To satisfy the requirements of on-machine measurement of the surface normal during complex surface manufacturing, a highly robust normal vector extraction method using an Eddy current (EC) displacement sensor array is developed, the output of which is almost unaffected by surface brightness, machining coolant and environmental noise. A precise normal vector extraction model based on a triangular-distributed EC sensor array is first established. Calibration of the effects of object surface inclination and coupling interference on measurement results, and the relative position of EC sensors, is involved. A novel apparatus employing three EC sensors and a force transducer was designed, which can be easily integrated into the computer numerical control (CNC) machine tool spindle and/or robot terminal execution. Finally, to test the validity and practicability of the proposed method, typical experiments were conducted with specified testing pieces using the developed approach and system, such as an inclined plane and cylindrical and spherical surfaces.
Eddy current monitoring of spacers in coolant channel assemblies of nuclear reactor
International Nuclear Information System (INIS)
Bhole, V.M.; Rastogi, P.K.; Kulkarni, P.G.; Vijayaraghavan, R.
1993-01-01
An eddy current testing method has been standardised for monitoring spacer springs which are used in coolant channel assemblies of pressurised heavy water nuclear reactors (PHWRs). The standard bobbin coil probe used for monitoring the spacer spring detects only the location but does not monitor the tilt orientation and tilt angle of a tilted spacer spring. The knowledge of location along with the tilt orientation of the spacer spring greatly improves the performance of repositioning methods. A modified probe with angular windings has been developed in laboratory tests for monitoring the location as well as the tilt orientation of the spacer springs. Experimental results are presented showing excellent performance of the modified probe in monitoring the exact location as well as tilt orientation of a spacer spring. The modified probe has also been used successfully in the field during repositioning of spacer springs in PHWRs before commissioning. (Author)
The interaction of pulsed eddy current with metal surface crack for various coils
International Nuclear Information System (INIS)
Yang, H.-C.; Tai, C.-C.
2002-01-01
We study the interaction of pulsed eddy current (PEC) with metal surface cracks using various coils that have different geometric sizes. In the previous work, we have showed that the PEC technique can be used to inspect electrical-discharge-machined (EDM) notches with depth from 0.5 mm to 9 mm. The results showed that the relationship between PEC signals and crack depth is obvious. In this work, we further try a series of coils with different radii, heights, turns and shapes. We will discuss the effects of these coil parameters on the PEC signal. Some other critical problems of PEC measurements such as signal drift that caused by heating effect of coil currents will be studied. We also show more experiments on fatigue cracks to demonstrate the capability of PEC technique for cracks inspection
Silent Flange Coupling Design Used for the Schenck Eddy Current Dynamometer
Schinteie, D.; Croitorescu, V.
2016-11-01
The silent flange used for coupling different machines/systems to an eddy current dynamometer represents one of the modular components each test-bench should use. By introducing a silent flange into a dynamometer, the coupling steps are easier and faster. For an appropriate design, the silent flange was analyzed using dedicated software during different operation procedures and scenarios, for materials that allow easy manufacturing. This study shows that the design for this silent flange model has no danger of failure due to the small deformation and the values for the equivalent stresses. The silent flange coupling is suitable for the dynamometer for his high positioning accuracy, the zero backlash and the fact that there is no motion between the shafts.
Mutlu, Ilven; Ekinci, Sinasi; Oktay, Enver
2014-06-01
This study presents nondestructive characterization of microstructure and mechanical properties of heat treated Ti, Ti-Cu, and Ti-6Al-4V titanium-based alloys and 17-4 PH stainless steel alloy for biomedical implant applications. Ti, Ti-Cu, and 17-4 PH stainless steel based implants were produced by powder metallurgy. Ti-6Al-4V alloy was investigated as bulk wrought specimens. Effects of sintering temperature, aging, and grain size on mechanical properties were investigated by nondestructive and destructive tests comparatively. Ultrasonic velocity in specimens was measured by using pulse-echo and transmission methods. Electrical conductivity of specimens was determined by eddy current tests. Determination of Young's modulus and strength is important in biomedical implants. Young's modulus of specimens was calculated by using ultrasonic velocities. Calculated Young's modulus values were compared and correlated with experimental values.
Eddy currents signal processing for steam generator inspection in PWR nuclear power plants
International Nuclear Information System (INIS)
Georgel, B.
1992-01-01
Steam generator tubes in nuclear power plants are periodically checked by means of eddy current probes. The output of a probe is composed of three types of signals: known events (rolling zone, support plates, U-bend part), noise (mainly metallurgical noise) and possible flaws. The latter are random transients, both in arrival time and in shape: they have to be detected and then estimated, before to be fed to the high level stages of a diagnostic system. The objective of the study presented is to develop a semi-automatic system, which could manage and process more than 1 M-bytes of data per tube and provide an operator with reliable diagnostics proposals within a few minutes. This can be achieved only by cooperation of several digital signal processing techniques: detection, segmentation, estimation, noise subtraction, adaptive filtering, modelization, pattern recognition. The paper describes some of these items
Eddy current and mechanical support of the wendelstein 7-X thermal shield
International Nuclear Information System (INIS)
Shim, S. Y.; Nagel, M.; Schauer, F.
2004-01-01
The machine which equipped huge magnet such as fusion reactor must be in need of special care on the emergency process. Rapid drop down magnetic field generate noticeable induced current, eddy current, and it causes strong electromagnetic forces on mechanical structure. The Wendelstein 7-X consists with 5 pentagonal shaped modules, plasma vessel, and each module can be divided into two symmetric half modules. Each half-module is going to be covered by 20 pieces of plasma vessel thermal shield (PVTS). The subject of this calculation is to find appropriate support positions for PVTS which can withstand self-weight of PVTS and electromagnetic force during the emergency case within our design criterion. We report the calculation procedure and results with half-module of PVTS
Evaluation of Eddy Current Signals from the Inner Wall Axial Cracks of Steam Generator Tubes
International Nuclear Information System (INIS)
Choi, Myung Sik; Hur, Do Haeng; Lee, Doek Hyun; Han, Jung Ho; Park, Jung Am
2001-01-01
For the enhancement of ECT reliability on the primary water stress corrosion cracks of nuclear steam generator tubes, of which the occurrence is on the increase, it is important to comprehend the signal characteristics on crack morphology and to select an appropriate probe type. In this paper, the sizing accuracy and the detectability for the inner wall axial cracks of tubes were quantitatively evaluated using the following specimens: the electric discharge machined notches and the corrosion cracks which were developed on the operating steam generator tubes. The difference of eddy current signal characteristics between pancake and axial coil were also Investigated. The results obtained from this study provide a useful information for more precise evaluation on the inner wall axial tracks oi steam generator tubes
The Defect Inspection on the Irradiated Fuel Rod by Eddy Current Test
International Nuclear Information System (INIS)
Koo, D. S.; Park, Y. K.; Kim, E. K.
1996-01-01
The eddy current test(ECT) probe of differential encircling coil type was designed and fabricated, and the optimum condition of ECT was derived for the examination of the irradiated fuel rod. The correlation between ECT test frequency and phase and amplitude was derived by performing the test of the standard rig that includes inner notches, outer notches and through-holes. The defect of through-hole was predicted by ECT at the G33-N2 fuel rod irradiated in the Kori-1 nuclear power reactor. The metallographic examination on the G33-N2 fuel rod was Performed at the defect location predicted by ECT. The result of metallographic examination for the G33-N2 fuel rod was in good agreement with that of ECT. This proves that the evaluation for integrity of irradiated fuel rod by ECT is reliable
Spatial-time-state fusion algorithm for defect detection through eddy current pulsed thermography
Xiao, Xiang; Gao, Bin; Woo, Wai Lok; Tian, Gui Yun; Xiao, Xiao Ting
2018-05-01
Eddy Current Pulsed Thermography (ECPT) has received extensive attention due to its high sensitive of detectability on surface and subsurface cracks. However, it remains as a difficult challenge in unsupervised detection as to identify defects without knowing any prior knowledge. This paper presents a spatial-time-state features fusion algorithm to obtain fully profile of the defects by directional scanning. The proposed method is intended to conduct features extraction by using independent component analysis (ICA) and automatic features selection embedding genetic algorithm. Finally, the optimal feature of each step is fused to obtain defects reconstruction by applying common orthogonal basis extraction (COBE) method. Experiments have been conducted to validate the study and verify the efficacy of the proposed method on blind defect detection.
Defect Shape Recovering by Parameter Estimation Arising in Eddy Current Testing
International Nuclear Information System (INIS)
Kojima, Fumio
2003-01-01
This paper is concerned with a computational method for recovering a crack shape of steam generator tubes of nuclear plants. Problems on the shape identification are discussed arising in the characterization of a structural defect in a conductor using data of eddy current inspection. A surface defect on the generator tube ran be detected as a probe impedance trajectory by scanning a pancake type coil. First, a mathematical model of the inspection process is derived from the Maxwell's equation. Second, the input and output relation is given by the approximate model by virtue of the hybrid use of the finite element and boundary element method. In that model, the crack shape is characterized by the unknown coefficients of the B-spline function which approximates the crack shape geometry. Finally, a parameter estimation technique is proposed for recovering the crack shape using data from the probe coil. The computational experiments were successfully tested with the laboratory data
Defect Detection and Segmentation Framework for Remote Field Eddy Current Sensor Data
Directory of Open Access Journals (Sweden)
Raphael Falque
2017-10-01
Full Text Available Remote-Field Eddy-Current (RFEC technology is often used as a Non-Destructive Evaluation (NDE method to prevent water pipe failures. By analyzing the RFEC data, it is possible to quantify the corrosion present in pipes. Quantifying the corrosion involves detecting defects and extracting their depth and shape. For large sections of pipelines, this can be extremely time-consuming if performed manually. Automated approaches are therefore well motivated. In this article, we propose an automated framework to locate and segment defects in individual pipe segments, starting from raw RFEC measurements taken over large pipelines. The framework relies on a novel feature to robustly detect these defects and a segmentation algorithm applied to the deconvolved RFEC signal. The framework is evaluated using both simulated and real datasets, demonstrating its ability to efficiently segment the shape of corrosion defects.
Modern methods of eddy-current testing for avoiding material mistakes
International Nuclear Information System (INIS)
Baumgartner, H.
1987-01-01
The conservation of raw materials and energy as a general goal in all fields is the reason why also in mechanical engineering and motor vehicle engineering, cross-sectional areas are reduced. The advantages thus obtained, - lower weight and lower manufacturing cost-, on the other hand require special core on the part of the manufacturer who has to enhance the testing activities in order to assure the appropriate structural conditions, also in mass production. Any wrong thermal treatment, or use of wrong material which remain undetected, may have disastrous effects. The eddy-current testing method now offers a mature procedure of quality assurance and is shown to be highly reliable with the attached computing equipment, guaranteeing 100 p.c. testing of manufactured goods. (orig.) [de
Model-Based Prediction of Pulsed Eddy Current Testing Signals from Stratified Conductive Structures
International Nuclear Information System (INIS)
Zhang, Jian Hai; Song, Sung Jin; Kim, Woong Ji; Kim, Hak Joon; Chung, Jong Duk
2011-01-01
Excitation and propagation of electromagnetic field of a cylindrical coil above an arbitrary number of conductive plates for pulsed eddy current testing(PECT) are very complex problems due to their complicated physical properties. In this paper, analytical modeling of PECT is established by Fourier series based on truncated region eigenfunction expansion(TREE) method for a single air-cored coil above stratified conductive structures(SCS) to investigate their integrity. From the presented expression of PECT, the coil impedance due to SCS is calculated based on analytical approach using the generalized reflection coefficient in series form. Then the multilayered structures manufactured by non-ferromagnetic (STS301L) and ferromagnetic materials (SS400) are investigated by the developed PECT model. Good prediction of analytical model of PECT not only contributes to the development of an efficient solver but also can be applied to optimize the conditions of experimental setup in PECT
Energy Technology Data Exchange (ETDEWEB)
Aguilo Valentin, Miguel Alejandro [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2016-07-01
This study presents a new nonlinear programming formulation for the solution of inverse problems. First, a general inverse problem formulation based on the compliance error functional is presented. The proposed error functional enables the computation of the Lagrange multipliers, and thus the first order derivative information, at the expense of just one model evaluation. Therefore, the calculation of the Lagrange multipliers does not require the solution of the computationally intensive adjoint problem. This leads to significant speedups for large-scale, gradient-based inverse problems.
Buck, J. A.; Underhill, P. R.; Morelli, J.; Krause, T. W.
2017-02-01
Degradation of nuclear steam generator (SG) tubes and support structures can result in a loss of reactor efficiency. Regular in-service inspection, by conventional eddy current testing (ECT), permits detection of cracks, measurement of wall loss, and identification of other SG tube degradation modes. However, ECT is challenged by overlapping degradation modes such as might occur for SG tube fretting accompanied by tube off-set within a corroding ferromagnetic support structure. Pulsed eddy current (PEC) is an emerging technology examined here for inspection of Alloy-800 SG tubes and associated carbon steel drilled support structures. Support structure hole size was varied to simulate uniform corrosion, while SG tube was off-set relative to hole axis. PEC measurements were performed using a single driver with an 8 pick-up coil configuration in the presence of flat-bottom rectangular frets as an overlapping degradation mode. A modified principal component analysis (MPCA) was performed on the time-voltage data in order to reduce data dimensionality. The MPCA scores were then used to train a support vector machine (SVM) that simultaneously targeted four independent parameters associated with; support structure hole size, tube off-centering in two dimensions and fret depth. The support vector machine was trained, tested, and validated on experimental data. Results were compared with a previously developed artificial neural network (ANN) trained on the same data. Estimates of tube position showed comparable results between the two machine learning tools. However, the ANN produced better estimates of hole inner diameter and fret depth. The better results from ANN analysis was attributed to challenges associated with the SVM when non-constant variance is present in the data.
DEFF Research Database (Denmark)
Lange, Katrine; Frydendall, Jan; Cordua, Knud Skou
2012-01-01
The frequency matching method defines a closed form expression for a complex prior that quantifies the higher order statistics of a proposed solution model to an inverse problem. While existing solution methods to inverse problems are capable of sampling the solution space while taking into account...... arbitrarily complex a priori information defined by sample algorithms, it is not possible to directly compute the maximum a posteriori model, as the prior probability of a solution model cannot be expressed. We demonstrate how the frequency matching method enables us to compute the maximum a posteriori...... solution model to an inverse problem by using a priori information based on multiple point statistics learned from training images. We demonstrate the applicability of the suggested method on a synthetic tomographic crosshole inverse problem....
International Nuclear Information System (INIS)
Jeong, Hyun Jo
1997-01-01
Ultrasonic and eddy current methods were developed for the quantitative determination of material properties in particulate reinforced metal matrix composites. The proposed techniques employed measurements of ultrasonic velocity and eddy current conductivity, together with theoretical models which relate the effective anisotropic properties of the composites to their microstructures. The approach was used for a wide range of SiC particulate reinforced Al matrix(SiC p /Al) composites to estimate the particulate volume fractions of the composites. The SiC p volume fraction was calculated by coupling the measured velocity and conductivity with their corresponding model predictions. Both methods were shown to be reliable in determining the reinforcement volume fractions. However, the ultrasonic method was found to be better than the eddy current method, since the electrical conductivity was sensitive to the presence of intermetallic compounds formed during processing stage.
International Nuclear Information System (INIS)
Johnson, M.J.; Nakagawa, N.; Wendt, S.E.; Hentscher, S.R.; Nelson, D.L.; Buhr, K.T.; Kilbugh, B.A.; Raithel, D.C.
2005-01-01
Eddy-current scans have been carried out on two Inconel-718 specimens following the application of various levels of shot peening and heat treatments. The conventional analysis of roughened or shot peened surfaces looks at multi-frequency impedance measurements and interprets the data as a change in conductivity or liftoff. An approach involving the statistical analysis of scanned eddy-current impedance data is suggested as an alternative that may provide a more sensitive way of determining the treatment history of a component. It is possible that an analysis of these statistical distributions in spatial eddy-current data could be used to determine the level of remaining residual stress in engine components
Directory of Open Access Journals (Sweden)
Mehmet Aytaç ÇINAR
2017-08-01
Full Text Available Low voltage winding leads cause local eddy current losses in top-plate of the transformer tank. In this paper, this loss component which also causes local hot spots is investigated. Top-plate design is modified using stainless steel non-magnetic material, around the low voltage bushing holes. Manufacturing issues and cost as well as power losses are considered as main criteria during modification study. Magnetic flux distributions and eddy current losses are analysed and compared for different designs. Comparisons are based on 3D finite element simulations and experimental studies. Obtained results show that, insertion of single I-shaped stainless steel plate reduces eddy current losses around low voltage bushing holes to nearly zero.
International Nuclear Information System (INIS)
Barat, P.; Raj, B.; Bhattacharya, D.K.
1982-01-01
Thin-walled nuclear fuel cladding tubes made of AISI 316 stainless steel have been examined by eddy-current testing. Standardization of the procedures has required investigations on optimizing the test frequency, finding a method to locate a defect with respect to the probe reference end, and the use of standard defects and sequential metallography of natural defects detected by eddy-current testing, to understand the influence of the nature of defects on the impedance output signals. Test frequency and method of locating the defect were optimized by the use of standard defects made by machining in reference cladding tubes. Subsequent metallography of natural defects detected by eddy-current testing revealed mainly clusters of inclusions but also other types of defects. The effect of the distribution of inclusions along the length of the tube on the impedance output is discussed. (author)
Energy Technology Data Exchange (ETDEWEB)
Barat, P; Raj, B; Bhattacharya, D K [Reactor Research Centre, Kalpakkam (India)
1982-10-01
Thin-walled nuclear fuel cladding tubes made of AISI 316 stainless steel have been examined by eddy-current testing. Standardization of the procedures has required investigations on optimizing the test frequency, finding a method to locate a defect with respect to the probe reference end, and the use of standard defects and sequential metallography of natural defects detected by eddy-current testing, to understand the influence of the nature of defects on the impedance output signals. Test frequency and method of locating the defect were optimized by the use of standard defects made by machining in reference cladding tubes. Subsequent metallography of natural defects detected by eddy-current testing revealed mainly clusters of inclusions but also other types of defects. The effect of the distribution of inclusions along the length of the tube on the impedance output is discussed.