- Email: [email protected]
Analysis of eddy current patterns
N DT Abstracts depth measurement by this formula can be negligible sections of the inducer’s wires are sufficiently long.
if the horizontal
and the computer, and the application of spectral identification examined. The structure of a system based on a matrix
evaluated
and a microcomputer is described. The in the interactive regime is and a method of minimizing this time examined.
45228
Al-Mouhamed,
transducers,
Takagi, T.; Hashimoto, S.; Miya, K.
45995
Arita, 3D numerical
M.; Sugiura,
T.; Norimatsu,
S.;
The Arabian Journal for Science and Engineering, pp. 453-463 (Jul. 1990)
44981 Nippon Nuclear Mite, K.T.)
J.C.
M.;
Flaws in an object may be detected using this new eddy current device. The test object is inserted between two detecting coils, each of which is connected by adjoining arms to a bridge circuit. This circuit outputs signals representing flaws in the test object. The coils are parallel to each other and inclined to the longitudinal axis of the test object by a predetermined angle. Once a flaw is detected by the bridge circuit the object is stopped and rotated relative to the coils to measure magnitude changes in the flaw signals. These are compared to those from flaws in a standard flaw test piece. Flaw signals are maximized by phase angle adjustment in a flaw signal processing and monitoring unit before the rotation.
models of the field-flaw interaction. Although the feasibility of inverting eddy current data in this fashion has been demonstrated before, the complexity of such procedures has hampered their widespread acceptance and use in industry. The goal of this study is to develop an inversion method that is easy to use and implement outside the research community. This paper presents preliminary results on the use of neural networks for the inversion of eddy current flaw signals to obtain flaw sizes.
44925
Dodd, C.Y.; Deeds, W.B.; McClung,
R.W.
Improved eddy-current inspection for steam generator tubing. Progress report for period January 1985December 1987
Jenkins, S.A.; Bowler, J.R.
Oak Ridge ORNL-TM-
Calculations of the flaw signal generated by a differential eddy current probe
National
Laboratory.,
Tennessee
I 1389, NUREG-CR-5478.37~~.
(United
States),
(Jan. 1989)
To idemify the critical flaw properties accurately and reliably in the presence of sign& caused by other property variations, the authors must have enough information to distinguish the flaw signals from the extraneous ones. Therefore, the authors developed instrumentation to measure both the amplitude and the phase of the eddy-current signal at several different frequencies, as well as computer equipment to process the data quickly and reliably. This need to detect small flaws in the presence of perturbing property variations has also required the development of more sensitive and more comp:icnted probes. such as pancake and reflection probes. These smaller coils can detect much smaller flaws and are less sensitive to artifacts outside the tube. such as tube supports, magnetic, or copper. To increase the inspection speed an array of these small coils has been constructed and
Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 23-28 Jul. 1989. Vol. 9A, pp 829- 835. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1990) Differential eddy-current probes are attractive because of their insensitivity to lift-off effects. By using two similar coils wound in opposition we have a sensor that detects variations in the magnetic field along a line joining their center. We have developed a three dimensional probe-flaw model to predict eddy-current signals based on a volume integral formulation. Although the benchmark problem examines the probe response due to a surface slot in a finite conducting slab, we have, instead, computed the signals due to a similar flaw in a half- space conductor. We shall highlight an effective method for calculating the differential signal. This aspect of the problem is of particular interest because it has proved to be very difficult to determine this signal using finite element methods.
tested.
44744 Tietze, M. New aspects in aircraft inspection using eddy current methods Impact
Stepinski, T.
of Emerging
NDE-NDI
Methods
on Aircraft
Design,
Manufacture and Maintenance, Brussels (Belgium), l-6 Oct. 1989. pp. 19-l - 19-S AGARD Conference Proceedings No. 462 (1990). ISBN 92 835 05468 Eddy current testing is one of the most effective tools to detect open or
Analysis of eddy current patterns 633 (Dec.
Co. Ltd.: (Urata,
U.S. Patent No. 4, 906,927 (6 Mar. 1990)
Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 23-28 Jul. 1989. Vol. 9A, pp. 6Sl- 688. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press ( 1990) Inversion of eddy current flaw signals has typically been based upon
63l-
Fuel Devebpment
Eddy current flaw detecting apparatus and method thereof
Inversion of uniform field eddy current data using neural networks
British Journal of Non-Destructive
Vol. 15, No. 3,
A portable microprocessor-controlled eddy current measuring system to automate qualitative testing of metallic bodies. The system embodies automatic setting of operating frequencies, self-tuning, and measures variations in impedance of the sensing coil that correspond to defects or variation of the materiel under test. Small changes in signal phase and amplitude are detected by fast hardware which is controlled by a microprocessor. Evaluation shows clear detection of defects upon phase analysis.
solved by many computer codes and to verify the modellings, numerical techniques, and computer codes. One of the TEAM workshop problems is an ECT (eddy current testing) problem. The purposes of this paper are as follows: (I) Development of practical eddy current analysis method using T method; (2) Measurement of signal trajectories for ECT of a block with a crack (TEAM problem No. 8); (3) Application of the method to the ECT problems and the verification of the method.
Mann, J.M.; Schmerr, L. W.; Moulder,
M.
Microprocessor-controlled eddy current measuring system for qualitative on-site testing
IESU~.S
45455
apparatus,
simulation of eddy current testing of a block with
Nondestructive Evaluation, Brunswick, Maine (United States), 23-28 Jul. 1989. Vol. 9A, pp. 327- 334. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1990) TEAM (Testing Electromagnetics Analysis Method) workshop is now going. The objectives of the TEAM workshop are to compare the numerical
45986
KAMAK
synthesis time of the image in operation
a crack Review of Progress in Quantitative
45989
methods, are eddy current
Testing, Vol. 32, No. 12, pp.
1990)
The paper concerns the problem of classification of material flaws based upon analysis of signals from eddy current (EC) systems for nondestructive material testing. The problem of distortion caused by the signal filters that are normally used in the EC systems is discussed first. The way of choosing these filters in order to minimise the distortion is presented. A novel method of characterising the eddy current patterns based on two-dimensional Fourier analysis of in-phase and quadrature signals is presented in the paper. It is shown that the EC patterns can be easily reconstructed from the two complex terms in the Fourier expansion and both low and high frequency noise can be efficiently filtered out during the reconstruction.
concealed corro+on and to assess damage caused by fatigue or corrosion cracking. The following describes the use of a meter type instrument for inspection of surface defects a?d a new impedance plane instrument that allows static and dynamic applications for detection of metal thinning due to corrosion, metal spacing. subsurface cracks ets. and for very quick fastener hole inspection. Finally new signal processing techniques for displaying flaw dimensions thrfiugh imaging procedures are discussed. All units described herein Ire pnrtable a13 battery operated. 44464
Ali, S.
Eddy current test for bolts 45445
Filist,
S.A.
Army Armament Research, Development and engineering Center, Dover, New Jersey (United States), AD-A214 829/4/GAR, 64 pp. (Nov. 1989)
Algorithmic and equipment means of spectral analysis in eddy current flaw inspection Soviet Journal of Nondestructive Testing, Vol. 26, No. 3, pp. 166-172 (Nov. 1990) Use of the Walsh-Admar transformation for identifying defects and eliminating
interference,
the distribution
of functions
The signai strength and the phase angle of the eddy current indication is a function of metal integrity, stand off yield strength, hardness, grain structure, and electrical conductivity. This concept was used to differentiate between grade 5.8. and 8.2 bolts. The statistical analysis of the data obtained
between the operator
180
if the horizontal
and the computer, and the application of spectral identification examined. The structure of a system based on a matrix
evaluated
and a microcomputer is described. The in the interactive regime is and a method of minimizing this time examined.
45228
Al-Mouhamed,
transducers,
Takagi, T.; Hashimoto, S.; Miya, K.
45995
Arita, 3D numerical
M.; Sugiura,
T.; Norimatsu,
S.;
The Arabian Journal for Science and Engineering, pp. 453-463 (Jul. 1990)
44981 Nippon Nuclear Mite, K.T.)
J.C.
M.;
Flaws in an object may be detected using this new eddy current device. The test object is inserted between two detecting coils, each of which is connected by adjoining arms to a bridge circuit. This circuit outputs signals representing flaws in the test object. The coils are parallel to each other and inclined to the longitudinal axis of the test object by a predetermined angle. Once a flaw is detected by the bridge circuit the object is stopped and rotated relative to the coils to measure magnitude changes in the flaw signals. These are compared to those from flaws in a standard flaw test piece. Flaw signals are maximized by phase angle adjustment in a flaw signal processing and monitoring unit before the rotation.
models of the field-flaw interaction. Although the feasibility of inverting eddy current data in this fashion has been demonstrated before, the complexity of such procedures has hampered their widespread acceptance and use in industry. The goal of this study is to develop an inversion method that is easy to use and implement outside the research community. This paper presents preliminary results on the use of neural networks for the inversion of eddy current flaw signals to obtain flaw sizes.
44925
Dodd, C.Y.; Deeds, W.B.; McClung,
R.W.
Improved eddy-current inspection for steam generator tubing. Progress report for period January 1985December 1987
Jenkins, S.A.; Bowler, J.R.
Oak Ridge ORNL-TM-
Calculations of the flaw signal generated by a differential eddy current probe
National
Laboratory.,
Tennessee
I 1389, NUREG-CR-5478.37~~.
(United
States),
(Jan. 1989)
To idemify the critical flaw properties accurately and reliably in the presence of sign& caused by other property variations, the authors must have enough information to distinguish the flaw signals from the extraneous ones. Therefore, the authors developed instrumentation to measure both the amplitude and the phase of the eddy-current signal at several different frequencies, as well as computer equipment to process the data quickly and reliably. This need to detect small flaws in the presence of perturbing property variations has also required the development of more sensitive and more comp:icnted probes. such as pancake and reflection probes. These smaller coils can detect much smaller flaws and are less sensitive to artifacts outside the tube. such as tube supports, magnetic, or copper. To increase the inspection speed an array of these small coils has been constructed and
Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 23-28 Jul. 1989. Vol. 9A, pp 829- 835. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1990) Differential eddy-current probes are attractive because of their insensitivity to lift-off effects. By using two similar coils wound in opposition we have a sensor that detects variations in the magnetic field along a line joining their center. We have developed a three dimensional probe-flaw model to predict eddy-current signals based on a volume integral formulation. Although the benchmark problem examines the probe response due to a surface slot in a finite conducting slab, we have, instead, computed the signals due to a similar flaw in a half- space conductor. We shall highlight an effective method for calculating the differential signal. This aspect of the problem is of particular interest because it has proved to be very difficult to determine this signal using finite element methods.
tested.
44744 Tietze, M. New aspects in aircraft inspection using eddy current methods Impact
Stepinski, T.
of Emerging
NDE-NDI
Methods
on Aircraft
Design,
Manufacture and Maintenance, Brussels (Belgium), l-6 Oct. 1989. pp. 19-l - 19-S AGARD Conference Proceedings No. 462 (1990). ISBN 92 835 05468 Eddy current testing is one of the most effective tools to detect open or
Analysis of eddy current patterns 633 (Dec.
Co. Ltd.: (Urata,
U.S. Patent No. 4, 906,927 (6 Mar. 1990)
Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 23-28 Jul. 1989. Vol. 9A, pp. 6Sl- 688. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press ( 1990) Inversion of eddy current flaw signals has typically been based upon
63l-
Fuel Devebpment
Eddy current flaw detecting apparatus and method thereof
Inversion of uniform field eddy current data using neural networks
British Journal of Non-Destructive
Vol. 15, No. 3,
A portable microprocessor-controlled eddy current measuring system to automate qualitative testing of metallic bodies. The system embodies automatic setting of operating frequencies, self-tuning, and measures variations in impedance of the sensing coil that correspond to defects or variation of the materiel under test. Small changes in signal phase and amplitude are detected by fast hardware which is controlled by a microprocessor. Evaluation shows clear detection of defects upon phase analysis.
solved by many computer codes and to verify the modellings, numerical techniques, and computer codes. One of the TEAM workshop problems is an ECT (eddy current testing) problem. The purposes of this paper are as follows: (I) Development of practical eddy current analysis method using T method; (2) Measurement of signal trajectories for ECT of a block with a crack (TEAM problem No. 8); (3) Application of the method to the ECT problems and the verification of the method.
Mann, J.M.; Schmerr, L. W.; Moulder,
M.
Microprocessor-controlled eddy current measuring system for qualitative on-site testing
IESU~.S
45455
apparatus,
simulation of eddy current testing of a block with
Nondestructive Evaluation, Brunswick, Maine (United States), 23-28 Jul. 1989. Vol. 9A, pp. 327- 334. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1990) TEAM (Testing Electromagnetics Analysis Method) workshop is now going. The objectives of the TEAM workshop are to compare the numerical
45986
KAMAK
synthesis time of the image in operation
a crack Review of Progress in Quantitative
45989
methods, are eddy current
Testing, Vol. 32, No. 12, pp.
1990)
The paper concerns the problem of classification of material flaws based upon analysis of signals from eddy current (EC) systems for nondestructive material testing. The problem of distortion caused by the signal filters that are normally used in the EC systems is discussed first. The way of choosing these filters in order to minimise the distortion is presented. A novel method of characterising the eddy current patterns based on two-dimensional Fourier analysis of in-phase and quadrature signals is presented in the paper. It is shown that the EC patterns can be easily reconstructed from the two complex terms in the Fourier expansion and both low and high frequency noise can be efficiently filtered out during the reconstruction.
concealed corro+on and to assess damage caused by fatigue or corrosion cracking. The following describes the use of a meter type instrument for inspection of surface defects a?d a new impedance plane instrument that allows static and dynamic applications for detection of metal thinning due to corrosion, metal spacing. subsurface cracks ets. and for very quick fastener hole inspection. Finally new signal processing techniques for displaying flaw dimensions thrfiugh imaging procedures are discussed. All units described herein Ire pnrtable a13 battery operated. 44464
Ali, S.
Eddy current test for bolts 45445
Filist,
S.A.
Army Armament Research, Development and engineering Center, Dover, New Jersey (United States), AD-A214 829/4/GAR, 64 pp. (Nov. 1989)
Algorithmic and equipment means of spectral analysis in eddy current flaw inspection Soviet Journal of Nondestructive Testing, Vol. 26, No. 3, pp. 166-172 (Nov. 1990) Use of the Walsh-Admar transformation for identifying defects and eliminating
interference,
the distribution
of functions
The signai strength and the phase angle of the eddy current indication is a function of metal integrity, stand off yield strength, hardness, grain structure, and electrical conductivity. This concept was used to differentiate between grade 5.8. and 8.2 bolts. The statistical analysis of the data obtained
between the operator
180