- Email: [email protected]
Flaw depth classification in eddy current tubing inspection by using neural network
N DT Abstracts deposits and copper deposits are presented and compared with corresponding signals from impedance coils. Theoretical and experimental results show that transmit-receive probes are able to detect defects in the presence of variable lift-off (due to tube-wall deformation) with ten times the signal-to-noise ratio as that exhibited by comparable pancake-type impedance probes. In addition, transmit- receive probes are less sensitive to magnetite deposits, and possess good phase discrimination to internal defects. 60814
Kah, C.S.; Mohammed,
O.A.; Jung, H-K.;
The application of artificial neural characterization in eddy current NDT
59679
to
defect
Proceedings of the International ISEM Symposium on Advanced Computational and Design Techniques in Applied Electromagnetic Systems, Seoul (Korea), 22-24 Jun. 1994, pp. 161-164. Edited by Song-yop Hahn, Elsevier (1995) ISBN 0444821392 An Artificial Neural Network (ANN) is applied to find out the defect in the conducting material. The ANN is trained with data set (defect parameters : defect signal output). where the defect signal is Lissajou’s figure and it is simulated using axisymmetric finite element method. 60130
Grimaldi,
59677
V.
measurements and calculations is described.
59676 L.A.
59444
LX;
K.
Cecco, VS.; Sullivan,
S.P.; Humphrey,
Mackintosh,
D.
ASNT 1994 Fall Conference and Quality Testing Show, Atlanta Georgia (United States), 19-23 Sep. 1994. pp. 130-I 32. ASNT (1994) ISBN 1- 57 I 17-002-2 Three experimental flaws were put into a tube to illustrate how a circumferential groove can be used as a calibration reference for a variety of different flaws. The flaws were a circumferential groove, a flat-milled flaw, and a permeability anomaly induced by heating and quenching. The Remote Field Eddy Current (RFEC) data were plotted both in strip chart format and on the voltage plane. Each flaw produces a unique, easily identifiable signal trace on the voltage plane. The trace for the circumferential groove follows the wall-thinning curve derived from skin-depth theory. The trace for the permeability anomaly follows the curve plotted using through-transmission equations. The signal from the flat-milled flaw lies inside the wall-thinning curve, as is expected from metal loss predominantly from one side of the tube. The depth and circumferential extent of the flat-milled flaw were calculated from the angle and length of the signal trace.
Review of Progress in Quantitative Nondestructive Evaluation, Snowmass Village, Colorado (United States), 31 Jul. -5 Aug. 1994. Vol. 14A. pp. 8 I I-818. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1995) ISBN o-306-45062-3. The phase angle of flaw signal pattern has been successfully used to estimate flaw depth in eddy current tubing in-service inspection. The authors have thought that flaw depth estimation should be accomplished by positively utilizing the phase angle of the flaw signal pattern which contains the flaw depth information. Thus the Fourier descriptor phase coefficients of flaw signal pattern have been derived as the input to neutral networks to classify flaw depth because the phase coefficients correlate directly with the pattern phase angle. Ohrutsky,
A.L.; Chernov,
Remote field eddy current inspection of ferromagnetic tubes
Flaw depth classification in eddy current tubing inspection by using neural network
59898
V.V.; Chernov,
Russian Journal of Nondestructive Testing, Vol. 30, No. IO, pp. 792- 796 (Oct. 1994) An approximate method of calculating the signals from a defect for a superposed eddy-current transducer is described using the following model: The object being monitored has an extended defect in the form of a nonferromagnetic half-space with the eddy-current transducer situated symmetrically above it. Approximate calculations are presented with existing results. The approximate expressions obtained can be used as the basis of an algorithm for calculating the depth of a defect.
Journal of JSNDI, Vol. 45, No. 1, pp. 52-60 (Jan. 1996) In remote field eddy current testing applied to ferromagnetic tube flaw testing, the length of the probe has to be greater than two tube diameters in principle. The experiment and finite element analysis showed that a conducting ferromagnetic shield plate inserted between the exciter and the detector decreases the direct propagation of the electromagnetic energy generated by the exciter inside the tube and hence the probe length can be reduced. The finite element analysis also revealed the electromagnetic energy flow path with the tube wall clarifying the effect of the conducting ferromagnetic shield plate. A small hole for signal wires can be made at the center of the shield plate with little deterioration of its shielding effect. Changing the position of the ferromagnetic shield plate hardly affects the shield plate’s effectiveness.
Transmit-receive eddy current cracks in heat exchanger tubes
Rolgin, K.V.; Sukhorukav,
Approximate method of calculating the signals from a defect for a superposed eddy-current transducer
605 I 1 Koyama, K.; Hnshikawa. H.; Fujii, T. Investigation of probe with magnetic shield for remote field eddy current testing (In Japanese, English abstract)
H.; Kayama,
D.L.
IEEE Transactions on Magnetics, Vol. 31, No. 6, Pt. 2, pp. 4142-4147 (Nov. 1995) The Remote Field Eddy Current (RFEC) technique uses an internal probe to inspect conducting tubes nondestructively. A coaxial solenoidal exciter, energized with low frequency AC, and detector coils near the inside of the pipe wall are separated by about two pipe diameters to obtain through wall transmission and equal sensitivity to defects on the outside or inside of the pipe wall. Calculation methodsare outlined and the voltage plane polar plot signal representation for defect measurement is described. Slit defect interactions in ferromagnetic and nonferromagnetic tubes are discussed. Defect-induced anomalous fields are interpreted in terms of anomalous source eddy current and missing magnetization defects models. The use of computer animations to represent the time variations of high resolution field
Electricite de France, Clamart (France), EDF-95NB-OOO29,49 pp. (Feb. 1994) This report describes an application of unsupervised neural networks for eddy current Non Destructive Testing (NDT) inspection of steam generator tubes. This is an original neural approach to defect detection, characterized by two aspects: diagnosis is expressed in architectural terms and the potential advantages of using unsupervised neural techniques are systematically discussed. We present the framework of the Kohenen self organizing maps within the proposed diagnosis architecture.
Hoshikawa,
Atherton,
Remote field eddy current inspection
Using unsupervised neural networks for eddy currents slgnature discrimination: a prospective study (In French)
60117
M.; Dawson, F.P.
IEEE Transactions on Magnetics, Vol. 31, No. 6, Pt. I, pp. 3185-3187 (Nov. 1995) This paper presents a new eddy-current probe composed of a microplanar mesh coil and meander coil. The probe can be used to detect the existence and the size of cracks in metallic structures. Experimental results for the sensed output voltage of this device are presented. The output signal is shown to have a discrete nature. Also, the results show that the signal strength is weak and that an offset voltage exists. Improved probe characteristics are obtained by connecting two mesh coils in series, stacking the coils on top of each other and orienting the two coils 180 degrees apart.
Hahn, S-y.
network
Yamada, S.; Katou, M.; Twahara,
Eddy current testing probe composed of planar coils
59440
Kumano,
S.; Kawase, N.; Kawata,
K.; Kurokawa,
A.
Signal processing of rotating pancake eddy current signal for steam generator tubes Proceedings of the 13th International Conference on NDE in the Nuclear and Pressure Vessel Industries, Kyoto (Japan), 22-25 May 1995. pp. 413- 421. ASM International (1995) ISBN o-87170-548-6 The technique to remove noises out of the rotating pancake eddy current signals is discussed. Our method combines the image processing techniques with the multi-frequency method. The two dimensional filter type is defined based on the heuristics, and the filter coefficients for signals with different scanning frequencies are statistically calculated so that the filtered output becomes similar to the desired signals. Our method was tested with the test pieces, which have EDM slits of 60% depth in the circular direction, metallic attachments of several thickness, and the tube sheet around the tube. The goal of the process was to remove the effects of noise elements,
D.
probes for circumferential
Materials Evaluation, Vol. 54. No. I, pp. 93-98 (Jan. 1996) This paper describes the basic features of T/R surface probes. Twodimensional voltage diagrams showing computer-derived probe response to frequency, lift-off, carbon steel supports, magnetite deposits and copper deposits are presented and compared with corresponding signals from impedance coils. Theoretical and experimental results show that T/R probes are able to detect defects in the presence of variable lift- off (due to tube-wall deformation) with ten times the signal-to-noise ratio as that exhibited by comparable pancake-type impedance probes.
whereas the effect of the slit is stored. The result showed the efficiency of
noise reduction power of our method.
172
Kah, C.S.; Mohammed,
O.A.; Jung, H-K.;
The application of artificial neural characterization in eddy current NDT
59679
to
defect
Proceedings of the International ISEM Symposium on Advanced Computational and Design Techniques in Applied Electromagnetic Systems, Seoul (Korea), 22-24 Jun. 1994, pp. 161-164. Edited by Song-yop Hahn, Elsevier (1995) ISBN 0444821392 An Artificial Neural Network (ANN) is applied to find out the defect in the conducting material. The ANN is trained with data set (defect parameters : defect signal output). where the defect signal is Lissajou’s figure and it is simulated using axisymmetric finite element method. 60130
Grimaldi,
59677
V.
measurements and calculations is described.
59676 L.A.
59444
LX;
K.
Cecco, VS.; Sullivan,
S.P.; Humphrey,
Mackintosh,
D.
ASNT 1994 Fall Conference and Quality Testing Show, Atlanta Georgia (United States), 19-23 Sep. 1994. pp. 130-I 32. ASNT (1994) ISBN 1- 57 I 17-002-2 Three experimental flaws were put into a tube to illustrate how a circumferential groove can be used as a calibration reference for a variety of different flaws. The flaws were a circumferential groove, a flat-milled flaw, and a permeability anomaly induced by heating and quenching. The Remote Field Eddy Current (RFEC) data were plotted both in strip chart format and on the voltage plane. Each flaw produces a unique, easily identifiable signal trace on the voltage plane. The trace for the circumferential groove follows the wall-thinning curve derived from skin-depth theory. The trace for the permeability anomaly follows the curve plotted using through-transmission equations. The signal from the flat-milled flaw lies inside the wall-thinning curve, as is expected from metal loss predominantly from one side of the tube. The depth and circumferential extent of the flat-milled flaw were calculated from the angle and length of the signal trace.
Review of Progress in Quantitative Nondestructive Evaluation, Snowmass Village, Colorado (United States), 31 Jul. -5 Aug. 1994. Vol. 14A. pp. 8 I I-818. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1995) ISBN o-306-45062-3. The phase angle of flaw signal pattern has been successfully used to estimate flaw depth in eddy current tubing in-service inspection. The authors have thought that flaw depth estimation should be accomplished by positively utilizing the phase angle of the flaw signal pattern which contains the flaw depth information. Thus the Fourier descriptor phase coefficients of flaw signal pattern have been derived as the input to neutral networks to classify flaw depth because the phase coefficients correlate directly with the pattern phase angle. Ohrutsky,
A.L.; Chernov,
Remote field eddy current inspection of ferromagnetic tubes
Flaw depth classification in eddy current tubing inspection by using neural network
59898
V.V.; Chernov,
Russian Journal of Nondestructive Testing, Vol. 30, No. IO, pp. 792- 796 (Oct. 1994) An approximate method of calculating the signals from a defect for a superposed eddy-current transducer is described using the following model: The object being monitored has an extended defect in the form of a nonferromagnetic half-space with the eddy-current transducer situated symmetrically above it. Approximate calculations are presented with existing results. The approximate expressions obtained can be used as the basis of an algorithm for calculating the depth of a defect.
Journal of JSNDI, Vol. 45, No. 1, pp. 52-60 (Jan. 1996) In remote field eddy current testing applied to ferromagnetic tube flaw testing, the length of the probe has to be greater than two tube diameters in principle. The experiment and finite element analysis showed that a conducting ferromagnetic shield plate inserted between the exciter and the detector decreases the direct propagation of the electromagnetic energy generated by the exciter inside the tube and hence the probe length can be reduced. The finite element analysis also revealed the electromagnetic energy flow path with the tube wall clarifying the effect of the conducting ferromagnetic shield plate. A small hole for signal wires can be made at the center of the shield plate with little deterioration of its shielding effect. Changing the position of the ferromagnetic shield plate hardly affects the shield plate’s effectiveness.
Transmit-receive eddy current cracks in heat exchanger tubes
Rolgin, K.V.; Sukhorukav,
Approximate method of calculating the signals from a defect for a superposed eddy-current transducer
605 I 1 Koyama, K.; Hnshikawa. H.; Fujii, T. Investigation of probe with magnetic shield for remote field eddy current testing (In Japanese, English abstract)
H.; Kayama,
D.L.
IEEE Transactions on Magnetics, Vol. 31, No. 6, Pt. 2, pp. 4142-4147 (Nov. 1995) The Remote Field Eddy Current (RFEC) technique uses an internal probe to inspect conducting tubes nondestructively. A coaxial solenoidal exciter, energized with low frequency AC, and detector coils near the inside of the pipe wall are separated by about two pipe diameters to obtain through wall transmission and equal sensitivity to defects on the outside or inside of the pipe wall. Calculation methodsare outlined and the voltage plane polar plot signal representation for defect measurement is described. Slit defect interactions in ferromagnetic and nonferromagnetic tubes are discussed. Defect-induced anomalous fields are interpreted in terms of anomalous source eddy current and missing magnetization defects models. The use of computer animations to represent the time variations of high resolution field
Electricite de France, Clamart (France), EDF-95NB-OOO29,49 pp. (Feb. 1994) This report describes an application of unsupervised neural networks for eddy current Non Destructive Testing (NDT) inspection of steam generator tubes. This is an original neural approach to defect detection, characterized by two aspects: diagnosis is expressed in architectural terms and the potential advantages of using unsupervised neural techniques are systematically discussed. We present the framework of the Kohenen self organizing maps within the proposed diagnosis architecture.
Hoshikawa,
Atherton,
Remote field eddy current inspection
Using unsupervised neural networks for eddy currents slgnature discrimination: a prospective study (In French)
60117
M.; Dawson, F.P.
IEEE Transactions on Magnetics, Vol. 31, No. 6, Pt. I, pp. 3185-3187 (Nov. 1995) This paper presents a new eddy-current probe composed of a microplanar mesh coil and meander coil. The probe can be used to detect the existence and the size of cracks in metallic structures. Experimental results for the sensed output voltage of this device are presented. The output signal is shown to have a discrete nature. Also, the results show that the signal strength is weak and that an offset voltage exists. Improved probe characteristics are obtained by connecting two mesh coils in series, stacking the coils on top of each other and orienting the two coils 180 degrees apart.
Hahn, S-y.
network
Yamada, S.; Katou, M.; Twahara,
Eddy current testing probe composed of planar coils
59440
Kumano,
S.; Kawase, N.; Kawata,
K.; Kurokawa,
A.
Signal processing of rotating pancake eddy current signal for steam generator tubes Proceedings of the 13th International Conference on NDE in the Nuclear and Pressure Vessel Industries, Kyoto (Japan), 22-25 May 1995. pp. 413- 421. ASM International (1995) ISBN o-87170-548-6 The technique to remove noises out of the rotating pancake eddy current signals is discussed. Our method combines the image processing techniques with the multi-frequency method. The two dimensional filter type is defined based on the heuristics, and the filter coefficients for signals with different scanning frequencies are statistically calculated so that the filtered output becomes similar to the desired signals. Our method was tested with the test pieces, which have EDM slits of 60% depth in the circular direction, metallic attachments of several thickness, and the tube sheet around the tube. The goal of the process was to remove the effects of noise elements,
D.
probes for circumferential
Materials Evaluation, Vol. 54. No. I, pp. 93-98 (Jan. 1996) This paper describes the basic features of T/R surface probes. Twodimensional voltage diagrams showing computer-derived probe response to frequency, lift-off, carbon steel supports, magnetite deposits and copper deposits are presented and compared with corresponding signals from impedance coils. Theoretical and experimental results show that T/R probes are able to detect defects in the presence of variable lift- off (due to tube-wall deformation) with ten times the signal-to-noise ratio as that exhibited by comparable pancake-type impedance probes.
whereas the effect of the slit is stored. The result showed the efficiency of
noise reduction power of our method.
172