- Email: [email protected]
Mascotte, an analytical model for eddy current signals
N DT Abstracts reference signal to generate a flaw signal representative of flaws in the metal
eddy current testing has been employed as a primary inspection tool. Detection of pitting has not caused a major inspection problem, but the traditional phase angle-to-pit depth analysis has not been reliable. This paper presents a more reliable sizing technique based on signal amplitude.
pipe. 565 12
Rajesh, S.N.
Probability of detection models for eddy current NDE methods
54758 Rajesh, S.N.; Udpa, L.; Udpa, S.S. Estimation of eddy current probability of detection (POD) using finite element method
Ames Lab., Iowa (United States), DE94007059/GAR, 106~~. (30 Apr. 1993) This thesis presents a comprehensive POD model for eddy current NDE. Eddy current methods of nondestructive testing are used widely in industry to inspect a variety of nonferromagnetic and ferromagnetic materials. The development of a comprehensive POD model is therefore of significant importance. The model incorporates several sources of variability characterized by a multivariate Gaussian distribution and employs finite element analysis to predict the signal distribution. The method of mixtures is then used for estimating optimal threshold values. The research demonstrates the use of a finite element model within a probabilistic frame-work to the spread in the measured signal for eddy current nondestructive methods.
Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 19-24 Jul. 1992. Vol. 12B, pp.2365-2372. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1993) ISBN 0- 306-44483-6 This paper presents a comprehensive POD model for eddy current NDE. The model incorporates several sources of variabilities characterized by a multivariate Gaussian distribution and employs the finite element method to predict the signal distribution. The paper demonstrates the use of a finite element model within a probabilistic framework to predict the spread of the measured signal for eddy current nondestructive methods. Using the signal distributions for various flaw sizes the probability of detection curves for defects of varying widths have been computed. Results demonstrating the value and utility of the approach are presented. In contrast to experimental POD models, the cost of generating such curves is very low and complex defect shapes can be handled very easily. The results are also operator independent.
55778 Gerasimnv, V.G.; Malov, V.M.; Efraimov, L.Y.; Evdokimov, P.A.
Eddy-current inspection of carbon components Russian Journal of Nondestructive Testing, Vol. 29, No. 9, pp. 643-649 (May 1994) Problems of eddy-current inspection of carbon-carbon composites are considered. A method is described for approximate calculation of signals of a superposed eddy-current transducer from defects of the crack type. The results are reported from experimental studies of samples of carbon-carbon composites with and without defects. The block diagram is given along with a description of the software for a device for detecting surface cracks in products made of those composites. 54987
54757 Placko. D.; Dufour, I. Eddy current sensors for nondestructive inspection of graphite composite materials 27th Annual Meeting of the Industry Applications, Houston (United States), 4-9 Oct. 1992. Vol. 2, pp. 1676-1682. IEEE (1992) ISBN 078030634 1 A system using eddy current sensors for nondestructive evaluation of graphite composite plates is described. First, the basic physical principle of measurements with this kind of sensors is recalled. Then, an analytical model of the relationships between the properties of the object approached in the sensitive area of the sensor and the induced variation of signal is presented: in our case, the interesting properties are the distance between the sensor and the plate, and its local conductivity. In the second part, the inversion of this model is discussed in view to extract the useful data from the sensor signal. This method is then illustrated in the case of a graphite composite plate on which a mechanical constraint is applied. The inspection process consists in scanning the sensor above the surface of the sample, and computing in each point either values of distance or conductivity. Both these results presented at successive steps of structure damages show simultaneously the surface deformations and the internal defects in the sample, demonstrating the interest of our method.
Delsarte, G.; Levy, R.
Mascotte, an analytical model for eddy current signals I I th International Conference and Exhibits on NDE in the Nuclear and Pressure Vessel Industries, Albuquerque, New Mexico (United States). 30 Apr. - 2 May 1992. pp. 283-288. ASM International (1992). ISBN O-87170- 446-3 Mascot@ a physical model including simple approximations, is applied to discontinuities such as wall-losses, inclusions and complex defects on a non ferromagnetic tube examined with a bobbin coil probe. The eddy current signal is described by analytical formulations which take into account the environmental parameters: tube dimension, probe design, excitation frequency, and physical features of the defect. Moreover, the simulated signal can be combined with the actual signal from a known discontinuity such as a supportplate. 54986 c.
Coutanceau-Monteil,
N.; Billy, F.; Cahouet. J.; Chavant.
54543 Wincheski, B.; Fulton, J.P.; Nath, S.; Namkung, M.; Simpson, J. W.
A complementary approach of 2D and 3D modeling for the understanding and the design of pulsed eddy current probes 1I th International Conference and Exhibits on NDE in the Nuclear
Self-nulling eddy current probe for surface and subsurface flaw detection Materials Evaluation, Vol. 52, No. 1, pp. 22-26 (Jan. 1994)
and Pressure Vessel Industries, Albuquerque, New Mexico (United States), 30 Apr. - 2 May 1992. pp. 273-276. ASM International (1992). ISBN O-87170- 446-3 In order to improve Pulsed Eddy Current (PEC) techniques for detecting and sizing subsurface cracks in non magnetic metals, numerical modelling and experiments are performed. The impulse response of the probe is simulated with a 2D finite element code and compared with experimental data. It is shown that 2D modelling for both axisymetrical and plane representations doesn’t simulate the interaction of the PEC probe with a subsurface plane electron-discharge machined (EDM) slot. On the contrary, 3D modelling performed with the TRIFOU code confirms experimental observations such as the. directivity of the probe and the tip effect from the slot. The sensitivity of the signal to the depth and orientation of the flaw and to the location and orientation of the receiving coil (i.e., various probes) is discussed. It is thus possible to size the length of the flaw through tip detection.
An eddy current probe. that provides a null-signal in the presence of unflawed material without the need for any balancing circuitry has been developed at NASA Langley Research Center. This capability reduces set-up time, eliminates tester configuration errors, and decreases instrumentation requirements. The probe is highly sensitive to surfacebreaking fatigue cracks, and shows excellent resolution for the measurement of material thickness, including material loss due to corrosion damage. The presence of flaws in the material under test causes an increase in the extremely stable and reproducible output voltage of the probe. The design of the probe and some examples illustrating its flaw detection capabilities are presented. 54283
Combustion Engineering Inc.; (Edwards, L.J.)
Method for detecting flaws in a steam generator tube using a flexible eddy current probe having coil band switching U.S. Patent No. 5,256,966 (26 Oct. 1993) A method of detecting flaws in a tube is described. It has a probe assembly with a probe heat with two sets of coils. A bank switch allows switching between the coils. Output signals are received which are transmitted over conductors from the coils, representative of the flaws.
54983 Krzywosz, K.; Henry, G.; O’Brien, J. Eddy current pit sizing techniques for copper alloy tubing 11th International Conference and Exhibits on NDE in the Nuclear and Pressure Vessel Industries, Albuquerque, New Mexico (United States), 30 Apr. - 2 May 1992. pp. 345-352. ASM International ( 1992). ISBN O-87170- 446-3 Copper based alloy tubing utilized in power plant heat exchangers is susceptible to pitting on the inside tube surface. Localized pitting is most damaging since it reduces load-carrying capacity and increases stress concentration by creating holes in the tube wall. To assesstubing integrity,
54222
Sakamoto, T.
Remote
field
ferromagnet.ic Abstract) Journal of
174
eddy
current
heat- exchanger
for (In Japanese:
examination tubes
U-shape English
JSNDI, Vol. 42, No. 10, pp. 563-569 (Oct. 1993)
eddy current testing has been employed as a primary inspection tool. Detection of pitting has not caused a major inspection problem, but the traditional phase angle-to-pit depth analysis has not been reliable. This paper presents a more reliable sizing technique based on signal amplitude.
pipe. 565 12
Rajesh, S.N.
Probability of detection models for eddy current NDE methods
54758 Rajesh, S.N.; Udpa, L.; Udpa, S.S. Estimation of eddy current probability of detection (POD) using finite element method
Ames Lab., Iowa (United States), DE94007059/GAR, 106~~. (30 Apr. 1993) This thesis presents a comprehensive POD model for eddy current NDE. Eddy current methods of nondestructive testing are used widely in industry to inspect a variety of nonferromagnetic and ferromagnetic materials. The development of a comprehensive POD model is therefore of significant importance. The model incorporates several sources of variability characterized by a multivariate Gaussian distribution and employs finite element analysis to predict the signal distribution. The method of mixtures is then used for estimating optimal threshold values. The research demonstrates the use of a finite element model within a probabilistic frame-work to the spread in the measured signal for eddy current nondestructive methods.
Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 19-24 Jul. 1992. Vol. 12B, pp.2365-2372. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1993) ISBN 0- 306-44483-6 This paper presents a comprehensive POD model for eddy current NDE. The model incorporates several sources of variabilities characterized by a multivariate Gaussian distribution and employs the finite element method to predict the signal distribution. The paper demonstrates the use of a finite element model within a probabilistic framework to predict the spread of the measured signal for eddy current nondestructive methods. Using the signal distributions for various flaw sizes the probability of detection curves for defects of varying widths have been computed. Results demonstrating the value and utility of the approach are presented. In contrast to experimental POD models, the cost of generating such curves is very low and complex defect shapes can be handled very easily. The results are also operator independent.
55778 Gerasimnv, V.G.; Malov, V.M.; Efraimov, L.Y.; Evdokimov, P.A.
Eddy-current inspection of carbon components Russian Journal of Nondestructive Testing, Vol. 29, No. 9, pp. 643-649 (May 1994) Problems of eddy-current inspection of carbon-carbon composites are considered. A method is described for approximate calculation of signals of a superposed eddy-current transducer from defects of the crack type. The results are reported from experimental studies of samples of carbon-carbon composites with and without defects. The block diagram is given along with a description of the software for a device for detecting surface cracks in products made of those composites. 54987
54757 Placko. D.; Dufour, I. Eddy current sensors for nondestructive inspection of graphite composite materials 27th Annual Meeting of the Industry Applications, Houston (United States), 4-9 Oct. 1992. Vol. 2, pp. 1676-1682. IEEE (1992) ISBN 078030634 1 A system using eddy current sensors for nondestructive evaluation of graphite composite plates is described. First, the basic physical principle of measurements with this kind of sensors is recalled. Then, an analytical model of the relationships between the properties of the object approached in the sensitive area of the sensor and the induced variation of signal is presented: in our case, the interesting properties are the distance between the sensor and the plate, and its local conductivity. In the second part, the inversion of this model is discussed in view to extract the useful data from the sensor signal. This method is then illustrated in the case of a graphite composite plate on which a mechanical constraint is applied. The inspection process consists in scanning the sensor above the surface of the sample, and computing in each point either values of distance or conductivity. Both these results presented at successive steps of structure damages show simultaneously the surface deformations and the internal defects in the sample, demonstrating the interest of our method.
Delsarte, G.; Levy, R.
Mascotte, an analytical model for eddy current signals I I th International Conference and Exhibits on NDE in the Nuclear and Pressure Vessel Industries, Albuquerque, New Mexico (United States). 30 Apr. - 2 May 1992. pp. 283-288. ASM International (1992). ISBN O-87170- 446-3 Mascot@ a physical model including simple approximations, is applied to discontinuities such as wall-losses, inclusions and complex defects on a non ferromagnetic tube examined with a bobbin coil probe. The eddy current signal is described by analytical formulations which take into account the environmental parameters: tube dimension, probe design, excitation frequency, and physical features of the defect. Moreover, the simulated signal can be combined with the actual signal from a known discontinuity such as a supportplate. 54986 c.
Coutanceau-Monteil,
N.; Billy, F.; Cahouet. J.; Chavant.
54543 Wincheski, B.; Fulton, J.P.; Nath, S.; Namkung, M.; Simpson, J. W.
A complementary approach of 2D and 3D modeling for the understanding and the design of pulsed eddy current probes 1I th International Conference and Exhibits on NDE in the Nuclear
Self-nulling eddy current probe for surface and subsurface flaw detection Materials Evaluation, Vol. 52, No. 1, pp. 22-26 (Jan. 1994)
and Pressure Vessel Industries, Albuquerque, New Mexico (United States), 30 Apr. - 2 May 1992. pp. 273-276. ASM International (1992). ISBN O-87170- 446-3 In order to improve Pulsed Eddy Current (PEC) techniques for detecting and sizing subsurface cracks in non magnetic metals, numerical modelling and experiments are performed. The impulse response of the probe is simulated with a 2D finite element code and compared with experimental data. It is shown that 2D modelling for both axisymetrical and plane representations doesn’t simulate the interaction of the PEC probe with a subsurface plane electron-discharge machined (EDM) slot. On the contrary, 3D modelling performed with the TRIFOU code confirms experimental observations such as the. directivity of the probe and the tip effect from the slot. The sensitivity of the signal to the depth and orientation of the flaw and to the location and orientation of the receiving coil (i.e., various probes) is discussed. It is thus possible to size the length of the flaw through tip detection.
An eddy current probe. that provides a null-signal in the presence of unflawed material without the need for any balancing circuitry has been developed at NASA Langley Research Center. This capability reduces set-up time, eliminates tester configuration errors, and decreases instrumentation requirements. The probe is highly sensitive to surfacebreaking fatigue cracks, and shows excellent resolution for the measurement of material thickness, including material loss due to corrosion damage. The presence of flaws in the material under test causes an increase in the extremely stable and reproducible output voltage of the probe. The design of the probe and some examples illustrating its flaw detection capabilities are presented. 54283
Combustion Engineering Inc.; (Edwards, L.J.)
Method for detecting flaws in a steam generator tube using a flexible eddy current probe having coil band switching U.S. Patent No. 5,256,966 (26 Oct. 1993) A method of detecting flaws in a tube is described. It has a probe assembly with a probe heat with two sets of coils. A bank switch allows switching between the coils. Output signals are received which are transmitted over conductors from the coils, representative of the flaws.
54983 Krzywosz, K.; Henry, G.; O’Brien, J. Eddy current pit sizing techniques for copper alloy tubing 11th International Conference and Exhibits on NDE in the Nuclear and Pressure Vessel Industries, Albuquerque, New Mexico (United States), 30 Apr. - 2 May 1992. pp. 345-352. ASM International ( 1992). ISBN O-87170- 446-3 Copper based alloy tubing utilized in power plant heat exchangers is susceptible to pitting on the inside tube surface. Localized pitting is most damaging since it reduces load-carrying capacity and increases stress concentration by creating holes in the tube wall. To assesstubing integrity,
54222
Sakamoto, T.
Remote
field
ferromagnet.ic Abstract) Journal of
174
eddy
current
heat- exchanger
for (In Japanese:
examination tubes
U-shape English
JSNDI, Vol. 42, No. 10, pp. 563-569 (Oct. 1993)