An investigation of the use of coils of different orientations for austenitic vessel inspection...
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some cases, digital enhancement of the images improved the detectability of the cracks. 43997 Treece,J.C.; Roberts, T.M.; Radecki, D.J.; Schunk, S.D. Detecting micro-structure and flaws in composites using eddy-current instrumentation Proceedings of the 15th Annual Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (USA), 31 Jul. - 5 Aug. 1988. Vol. 8B, pp. 1519-1526. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1989). ISBN 0-306-43209-9. We describe our procedure and experimental results for gathering eddy- current measurements that indicate internal features of advanced composite materials. Our measurements of the EMF were made using inductive sensors, excited by various current sources, near samples of material. The EMF measurements, made in the range of 100kHz to 50MHz, indicate features such as fiber tows, impact damage flaws, drilled holes, and weave structure of the material. Laboratory data and model calculations are presented. Computer- controlled electronic instrumentation that uses phase-sensitive techniques measures the amplitude and phase of the induced sensor signal. 43726 Fisher, J.L.; Rowland, S.N.; Baiter, F.A.; Stolte, S.S.: Pickens, K.S. A cryogenic eddy current microprobe Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D. O. Thompson and D.E. Chimenti, pp. 959-965. Plenum Press (1989) ISBN 0 306 43209 9 The primary objective of the subject work was to develop small normally conducting eddy current probes with ultra high resolution that functioned at 77 Kelvins (K). The probes consisted of a hybrid electronics package including a sensing-coil array and preamplifier electronics mounted on a single substrate with an excitation coil. development of fabrication techniques adaptable to the use of SQUID detectors was part of the project. A secondary objective was to develop photolithographic techniques for eddy current probe production. The purpose was to allow fabrication of probes with precisely controlled and repeatable geometry and electromagnetic characteristics. 43725 Burkhardt, G.L. Eddy current probe performance characterization Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D. O. Thompson and D.E. Chimenti, pp. 967-974. Plenum Press (1989) ISBN 0 306 43209 9 An experimental evaluation of thirty shielded and thirty non-shielded surface probes was conducted to determine probe performance with a specific eddy current instrument being adopted for widespread use by the Air Force. This paper describes preliminary results of the investigation and shows the results of measurements of the following parameters for shielded and nonshielded probes: (1) liftoff "noise", (2) tilt "noise", (3) effect of liftoff on flaw response, and (4) effect of tilt on flaw response. Suggested acceptance criteria are given for the four measured parameters, as well as the percentages of probes which could meet the criteria. 43724 Hedengren, K.H.; McCary,R.O.; Young, J.D. Eddy current probe evaluation: experimental measurements and system interaction Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D. O. Thompson and D.E. Chimenti, pp. 975-983. Plenum Press (1989) ISBN 0 306 43209 9 This paper describes work that combines imaging with probe measurements to analyze eddy current probes and system performance from a practical point of view. Slightly different designs of a specific type of probe have been examined to evaluate differences in the designs and to determine how well the probe have been examined to evaluate differences in the designs and to determine how well the probe have been examined to evaluate differences in the designs and to determine how well the probe construction method is controlled. 43723 Capobiance, T.E.; Ciciora, S.J.; Moulder, J.C. Standard flaws for eddy current probe characterization Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D. O. Thompson and D.E. Chimenti, pp. 985-989. Plenum Press (1989) ISBN 0 306 43209 9 Calibration procedures for eddy current inspection often involve the use of artifact standards containing manufactured flaws. We describe here a technique for consistently producing well characterized discontinuities in aluminum which are non subject to problems of (a) phase difference between milled slots and real fatigue cracks, and (b) electrical contact when crack faces are driven together. 43721 Beissner, R.E.; Temple, J.A.G. A Users guide and manual to the computer program PIERCE: probe impedance eddy current response to cracks United Kingdom Atomic Energy Authority, Harwell, AERE-R- 13507, 43pp (May 1989) Eddy currents are one non-destructive technique for detecting and characterising surface breaking cracks in conducting materials. The impedance of the eddy current probe changes as the probe is scanned over a crack. PIERCE calculates these impedance changes for a given probe geometry and a three dimensional defect. Magnetic scalar potential theory and the surface impedance approximation are used to calculate fields on the flaw surface. The magnetic scalar potential is obtained numerically by the boundary element method as a solution to a boundary integral equation. This leads to an efficient computational procedure which has been implemented on a CRAY-2 computer. An example of the probe impedance changes in the region near a sh)t are giver). The theory behind the program and details of its use are given. 43720 Alam, M.Z.; Khan, M.R.; Rahman, S.M. An empirical model for nondestructive metal testing using eddy current British Journal of Non-Destructive Testing, Vol. 32, No. 4, pp. 193-196 (Apr. 1990) Electromagnetic behaviour of simulated faults in nonferrous metals are studied. A very simple probe and circuit configuration was used to obtain the experimental results. An empirical model was derived from simplified fault analysis. The unknown coefficients were evaluated using measured results and the frequency response was interpreted in terms of the fault parameters. 43719 Clark, R.; Bond, L.J. An investigation of the use of coils of different orientations for austenitic vessel inspection using eddy currents Impact of Non-Destructive Testing, Proceedings of the 28th Annual British Conference on Non-Destructive Testing, Sheffield (United Kingdom), 18-21 Sep. 1989. pp. 211-219. Edited by C. Brook and P.D. Hanstead. Pergamon Press, (1990) This paper will consider a comparison between horizontal axis coils and the more conventional vertical axis coils used for eddy current inspection. Both coil orientations will be investigated for austenitic stainless steel vessel inspection, as required in both nuclear and chemical plant. Experimental and theoretical work are considered, and particular attention will be given to inspection of the austenitic weld regions of the vessel. 43718 Haywood, N.C.; Harrison, D.J.; Bowler, J.R. The imaging of cracks using eddy-currents Impact of Non-Destructive Testing, Proceedings of the 28th Annual British Conference on Non-Destructive Testing, Sheffield (United Kingdom), 18-21 Sep. 1989. pp. 231-240. Edited by C. Brook and P.D. Hanstead. Pergamon Press, (1990) When eddy-current flow in a cracked conductor, an oscillating dipole distribution is created on the length of the crack and this gives rise to a scattered magnetic field above the conductor. We have sampled this field with a Hall transducer which has a point-like response function. We show that this magnetic field is then the convolution of the dipole distribution with the material response function, represented by Green's function. Since the dipole distribution only resides on the crack, it effectively represents and image of the crack. Examples of images obtainable using this technique are presented in this paper. 43492 Smith, L.E. W. Eddy current probe manufacture Non-Destructive Testing Australia, Vol. 26, No. 5, pp. 120-122 (Sep. Oct. 1989) This report offers prospective manufacturers of eddy current probes a basic knowledge of the complexities in the design of such probes, in order to speed the manufacture of specialised probes for the Australian market. Coil configurations probe shape and operating frequency and shielding of the coil are all considered. The processes involved in probe construction are also described. 43490 Bruce, D.A.; Stone, D.E.W. The reliability of rotating probe eddy-current inspection techniques for fastener holes in aircraft Reliability in Non-Destructive Testing, Proceedings of the 27th Annual British Conference on Non-Destructive Testing, Portsmouth (United Kingdom), 12-15 Sep. 1988. pp. 45-64. Edited by C. Brook and P.D. Hanstead. Pergamon Press, 1989. The statistical procedures necessary for the derivation of data on the reliability of inspection are reviewed. A recent UK (MOD) programme is described and the results of a preliminary analysis are presented. 43487 Udpa, L. ; Udpa, S.S. Eddy current defect characterization using neural networks Materials Evaluation, Vol. 48, No. 3, pp. 342-347 (Mar. 1990) This paper proposes the use of neural networks for interpreting signals from eddy current probes used in nondestructive testing (NDT). Classification results obtained by implementing a multilayered neural network using the back- propagation algorithm are presented. The merits of this approach as well as a comparison with traditional techniques for the classification of signals are also discussed. 43485 Nath, S. ; Lord, W.; Sun, Y.S. Theoretical and experimental studies on the remote field eddy current effect Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D.C. Thompson and D.E. Chimenti, pp. 267-274. Plenum Press (1989), ISBN 0 306 43209 9 Conventional eddy current nondestructive testing methods, based on the principle of electromagnetic induction have been used over the years for defect detection. Skin effect characteristics limit the eddy currents to the surface of the material, restricting the conventional EC testing methods to the detection of near surface inhomogeneities. The remote field eddy current probe in contrast overcomes the above limitation due to its apparent sensitivity to both inner and outer diameter defects. Recently numerical models have been developed to develop a better understanding of the physics of the phenomenon. 358 NDT International December 1990
Transcript of An investigation of the use of coils of different orientations for austenitic vessel inspection...
some cases, digital enhancement of the images improved the detectability of the cracks.
43997 Treece, J.C.; Roberts, T.M.; Radecki, D.J.; Schunk, S.D. Detecting micro-structure and flaws in composites using eddy-current instrumentation Proceedings of the 15th Annual Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (USA), 31 Jul. - 5 Aug. 1988. Vol. 8B, pp. 1519-1526. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1989). ISBN 0-306-43209-9.
We describe our procedure and experimental results for gathering eddy- current measurements that indicate internal features of advanced composite materials. Our measurements of the EMF were made using inductive sensors, excited by various current sources, near samples of material. The EMF measurements, made in the range of 100kHz to 50MHz, indicate features such as fiber tows, impact damage flaws, drilled holes, and weave structure of the material. Laboratory data and model calculations are presented. Computer- controlled electronic instrumentation that uses phase-sensitive techniques measures the amplitude and phase of the induced sensor signal.
43726 Fisher, J.L.; Rowland, S.N.; Baiter, F.A.; Stolte, S.S.: Pickens, K.S. A cryogenic eddy current microprobe Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D. O. Thompson and D.E. Chimenti, pp. 959-965. Plenum Press (1989) ISBN 0 306 43209 9
The primary objective of the subject work was to develop small normally conducting eddy current probes with ultra high resolution that functioned at 77 Kelvins (K). The probes consisted of a hybrid electronics package including a sensing-coil array and preamplifier electronics mounted on a single substrate with an excitation coil. development of fabrication techniques adaptable to the use of SQUID detectors was part of the project. A secondary objective was to develop photolithographic techniques for eddy current probe production. The purpose was to allow fabrication of probes with precisely controlled and repeatable geometry and electromagnetic characteristics.
43725 Burkhardt, G.L. Eddy current probe performance characterization Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D. O. Thompson and D.E. Chimenti, pp. 967-974. Plenum Press (1989) ISBN 0 306 43209 9
An experimental evaluation of thirty shielded and thirty non-shielded surface probes was conducted to determine probe performance with a specific eddy current instrument being adopted for widespread use by the Air Force. This paper describes preliminary results of the investigation and shows the results of measurements of the following parameters for shielded and nonshielded probes: (1) liftoff "noise", (2) tilt "noise", (3) effect of liftoff on flaw response, and (4) effect of tilt on flaw response. Suggested acceptance criteria are given for the four measured parameters, as well as the percentages of probes which could meet the criteria.
43724 Hedengren, K.H.; McCary,R.O.; Young, J.D. Eddy current probe evaluation: experimental measurements and system interaction Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D. O. Thompson and D.E. Chimenti, pp. 975-983. Plenum Press (1989) ISBN 0 306 43209 9
This paper describes work that combines imaging with probe measurements to analyze eddy current probes and system performance from a practical point of view. Slightly different designs of a specific type of probe have been examined to evaluate differences in the designs and to determine how well the probe have been examined to evaluate differences in the designs and to determine how well the probe have been examined to evaluate differences in the designs and to determine how well the probe construction method is controlled.
43723 Capobiance, T.E.; Ciciora, S.J.; Moulder, J.C. Standard flaws for eddy current probe characterization Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D. O. Thompson and D.E. Chimenti, pp. 985-989. Plenum Press (1989) ISBN 0 306 43209 9
Calibration procedures for eddy current inspection often involve the use of artifact standards containing manufactured flaws. We describe here a technique for consistently producing well characterized discontinuities in aluminum which are non subject to problems of (a) phase difference between milled slots and real fatigue cracks, and (b) electrical contact when crack faces are driven together.
43721 Beissner, R.E.; Temple, J.A.G. A Users guide and manual to the computer program PIERCE: probe impedance eddy current response to cracks United Kingdom Atomic Energy Authority, Harwell, AERE-R- 13507, 43pp (May 1989)
Eddy currents are one non-destructive technique for detecting and characterising surface breaking cracks in conducting materials. The impedance of the eddy current probe changes as the probe is scanned over a crack. PIERCE calculates these impedance changes for a given probe geometry and a three dimensional defect. Magnetic scalar potential theory and the surface impedance approximation are used to calculate fields on the flaw surface. The magnetic scalar potential is obtained numerically by the boundary element method as a solution to a boundary integral equation. This leads to an efficient
computational procedure which has been implemented on a CRAY-2 computer. An example of the probe impedance changes in the region near a sh)t are giver). The theory behind the program and details of its use are given.
43720 Alam, M.Z.; Khan, M.R.; Rahman, S.M. An empirical model for nondestructive metal testing using eddy current British Journal of Non-Destructive Testing, Vol. 32, No. 4, pp. 193-196 (Apr. 1990)
Electromagnetic behaviour of simulated faults in nonferrous metals are studied. A very simple probe and circuit configuration was used to obtain the experimental results. An empirical model was derived from simplified fault analysis. The unknown coefficients were evaluated using measured results and the frequency response was interpreted in terms of the fault parameters.
43719 Clark, R.; Bond, L.J. An investigation of the use of coils of different orientations for austenitic vessel inspection using eddy currents Impact of Non-Destructive Testing, Proceedings of the 28th Annual British Conference on Non-Destructive Testing, Sheffield (United Kingdom), 18-21 Sep. 1989. pp. 211-219. Edited by C. Brook and P.D. Hanstead. Pergamon Press, (1990)
This paper will consider a comparison between horizontal axis coils and the more conventional vertical axis coils used for eddy current inspection. Both coil orientations will be investigated for austenitic stainless steel vessel inspection, as required in both nuclear and chemical plant. Experimental and theoretical work are considered, and particular attention will be given to inspection of the austenitic weld regions of the vessel.
43718 Haywood, N.C.; Harrison, D.J.; Bowler, J.R. The imaging of cracks using eddy-currents Impact of Non-Destructive Testing, Proceedings of the 28th Annual British Conference on Non-Destructive Testing, Sheffield (United Kingdom), 18-21 Sep. 1989. pp. 231-240. Edited by C. Brook and P.D. Hanstead. Pergamon Press, (1990)
When eddy-current flow in a cracked conductor, an oscillating dipole distribution is created on the length of the crack and this gives rise to a scattered magnetic field above the conductor. We have sampled this field with a Hall transducer which has a point-like response function. We show that this magnetic field is then the convolution of the dipole distribution with the material response function, represented by Green's function. Since the dipole distribution only resides on the crack, it effectively represents and image of the crack. Examples of images obtainable using this technique are presented in this paper.
43492 Smith, L.E. W. Eddy current probe manufacture Non-Destructive Testing Australia, Vol. 26, No. 5, pp. 120-122 (Sep. Oct. 1989)
This report offers prospective manufacturers of eddy current probes a basic knowledge of the complexities in the design of such probes, in order to speed the manufacture of specialised probes for the Australian market. Coil configurations probe shape and operating frequency and shielding of the coil are all considered. The processes involved in probe construction are also described.
43490 Bruce, D.A.; Stone, D.E.W. The reliability of rotating probe eddy-current inspection techniques for fastener holes in aircraft Reliability in Non-Destructive Testing, Proceedings of the 27th Annual British Conference on Non-Destructive Testing, Portsmouth (United Kingdom), 12-15 Sep. 1988. pp. 45-64. Edited by C. Brook and P.D. Hanstead. Pergamon Press, 1989.
The statistical procedures necessary for the derivation of data on the reliability of inspection are reviewed. A recent UK (MOD) programme is described and the results of a preliminary analysis are presented.
43487 Udpa, L. ; Udpa, S.S. Eddy current defect characterization using neural networks Materials Evaluation, Vol. 48, No. 3, pp. 342-347 (Mar. 1990)
This paper proposes the use of neural networks for interpreting signals from eddy current probes used in nondestructive testing (NDT). Classification results obtained by implementing a multilayered neural network using the back- propagation algorithm are presented. The merits of this approach as well as a comparison with traditional techniques for the classification of signals are also discussed.
43485 Nath, S. ; Lord, W.; Sun, Y.S. Theoretical and experimental studies on the remote field eddy current effect Review of Progress in Quantitative Nondestructive Evaluation, Vol. 8A. Edited by D.C. Thompson and D.E. Chimenti, pp. 267-274. Plenum Press (1989), ISBN 0 306 43209 9
Conventional eddy current nondestructive testing methods, based on the principle of electromagnetic induction have been used over the years for defect detection. Skin effect characteristics limit the eddy currents to the surface of the material, restricting the conventional EC testing methods to the detection of near surface inhomogeneities. The remote field eddy current probe in contrast overcomes the above limitation due to its apparent sensitivity to both inner and outer diameter defects. Recently numerical models have been developed to develop a better understanding of the physics of the phenomenon.
358 NDT International December 1990
