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Acoustic emission in low-cyclic fatigue
maximum stress intensity, crack growth rate, yield stress and microstructure is shown. 37688 Tonolini, F.; Sala, A.; Villa, G. General review of developments in acoustic emission methods I ntern ational Journal of Pressure Vessels and Piping, Vol. 28, No. 1-5, pp. 179-201 (1987) The ability of Acoustic Emission (AE) to detect, with high sensitivity, the mechanical energy released by flow evolution, may be used to get information about crack growth, onset of new defects and their dynamic behaviour, during the first hydrotest and later requalification testing of nuclear components and continuous monitoring of power plant operation. In this review, the most recent developments in AE for nuclear component monitoring are examined. Suitable AE equipment for logging high rates of AE data, real-time source location and parametric analysis are discussed. 37687
Carpenter, S.H.; Armstrong, J.; Heiple, C.R.
Detection of hydrogen-assisted crack growth by measurement of modulus changes and acoustic emission Corrosion Monitoring in Industrial Plants using Nondestructive Testing and Electrochemical Methods. A symposium sponsored by A S T M C o m m i t t e e E-7 on Nondestructive Testing and C o m m i t t e e G-1 on Corrosion of Metals, Montreal, Canada, 22-24 May 1984. pp. 165-178. A S T M Special Technical Publication 908 An investigationof new techniques to probe and study the initiation of cracks in a hydrogen environment is reported. The techniques investigated are the precise continuous measurement of changes in the elastic modulus and acoustic emission measurements. A decrease in the elastic modulus should be observed as cracks nucleate and grow in a test material. Measurements of changes in the elastic modulus while cathodically charging a number of iron base materials both at zero load and under applied load are also given. In all cases a decrease in the elastic modulus was observed as a result of cathodic charging with hydrogen. The modulus loss was found to be permanent and could not be restored by heat treatment. Acoustic emission measurement were carried out as miniature pressure vessels were pressurized and subsequently held at pressure. Differences in the acoustic emission were observed for vessels pressurized with hydrogen gas as compared to vessels pressurized with helium. Considerably more acoustic emission was generated in vessels pressurized with hydrogen. 37686
Martin, P.; Dickson, J.L; Bailon, J.-P.
Monitoring stress-corrosion cracking by acoustic emission Corrosion Monitoring in Industrial Plants using Nondestructive Testing and Electrochemical Methods. A symposium sponsored by A S T M C o m m i t t e e E-7 on Nondestructive Testing and C o m m i t t e e G-1 on Corrosion of Metals, Montreal, Canada, 22-24 May 1984. pp. 75-88. A S T M Special Technical Publication 908 Acoustic emission (AE) is well suited for laboratory studies of stress corrosion cracking (SCC) since the crack velocity is often approximately proportional to the AE rate. For 7075-T651 and 2024-T351 aluminum alloys, this proportionality is shown to be particularly good. For 7075-T651, less scatter is obtained in SCC crack velocity when these are based on the cumulative AE counts than on surface crack length measurements. The curve of AE rate versus time after addition of fresh solution into the crack depends on the type of transducer employed. Using either a broad-band or a resonant transducer, it was possible to distinguish between SCC and corrosion signals from their frequency spectrum. The applicability of employing AE to detect SCC in an industrial environment is considered. Possible solutions to some of the difficulties expected in cases where SCC produces low-amplitude AE signals are discussed. 37685
Yuyama, S.
Fundamental aspects of acoustic emission applications to the problems caused by corrosion Corrosion Monitoring in Industrial Plants using Nondestructive Testing and Electrochemical Methods. A symposium sponsored by A S T M C o m m i t t e e E-7 on Nondestructive Testing and C o m m i t t e e G-1 on Corrosion of Metals, Montreal, Canada, 22-24 May 1984. pp. 43-74. A S T M Special Technical Publication 908 This paper describes the use of acoustic emission (AE) for the detection and monitoring of corrosion, stress corrosion cracking (SCC), and corrosion fatigue (CF). It surveys laboratory studies and field applications that have been made to date. The application of the technique to fundamental studies in the laboratory and continuous monitoring in engineering structures are discussed in detail. Various microprocesses that can produce detectable AE are shown and their relative energy levels, emanated as AE, are discussed in terms of peak amplitudes measured on laboratory specimens by a conventional piezoelectric sensor.
37684
Pollock, A.A.
Acoustic emission capabilities and applications in monitoring corrosion Corrosion Monitoring in Industrial Plants using Nondestructive Testing and Electrochemical Methods. A symposium sponsored by A S T M C o m m i t t e e E-7 on Nondestructive Testing and C o m m i t t e e G-1 on Corrosion of Metals, Montreal, Canada, 22-24 May 1984. pp. 30-42. A S T M Special Technical Publication 908 The physical processes of corrosion are examined as possible sources of acoustic emission (AE). Detectable emission is produced by film cracking, gas evolution, hydrogen-induced microcracking, plastic zone growth, and discontinuous crack movements in stress-corrosion cracking (SCC) and
NDT International April 1989
hydrogen-assisted cracking. By these mechanisms corrosion can be detected while it is occurring. Practical applications include rapid evaluation of the susceptibility of materials to corrosion, particularly to SCC. Apart from real-time monitoring of the corrosion process, the structural damage caused by corrosion can be detected after it has occured by AE monitoring during application of stress. In this testing mode, emission is enhanced by surface degradation and corrosion products. Pipelines and aircraft structures have been tested in this way. In large structures it is generally more practical to detect the results of corrosion than to monitor the corrosion process itself. For success in field applications attention must be paid to issues such as background noise and wave attenuation, and operator training and experience is an important factor. 37680
Kim, K.H.; Kishi, T.
Three dimensional AE source location in metals Nondestructive Testing C ommuni c a t i ons , Vol. 3, No. 3, pp. 75-88 (1987) An acoustic wave emitted.from microcracks or inclusions was detected by six transducers mounted on the specimen, then amplified and digitized by a highly efficient wave memory system. Three dimensional location of defects was carried out using, 3 types of Ti alloys, A533B steel, and A470 steel. Differences in the tendency to form microcracks in different fracture modes was confirmed. 37485
Ivanov, V.L; Kuranov, V.N.; Ryabov, A.N.
Acoustic emission in low-cyclic fatigue Soviet Physics D okl a dy, Vol. 31, No. 6, pp. 517-518 (Jun. 1986) Well established theory and experimental data are used to develop a model of fatigue-crack growth (FCG). Pulsed elastic waves are emitted from a strain resistant but brittle material embedded in a material still prone to plastic deformation when the brittle material is caused to increase in volume. In addition to this acoustic emission, a crack is found to jump along the boundary of the two materials. A physically well defined parameter, easily verified experimentally is proposed to estimate the growth rate of fatigue cracks. 37484
Wadley, H.N.G.
Acoustic emission: A quantitative NDE technique for the study of fracture Solid Mechanics Research for Q ua nt i t a t i ve Nondestructive Evaluation, Proceedings of the O N R Symposium on Solid Mechanics Research for Q N D E , Northwestern University, Evanston, Illinois (United States), 18-20 Sep. 1985 pp. 25-40. Martinus Nijhoff Publishers (1987) Acoustic emission, an NDE technique that shows promise for detecting and locating cracks in engineering structures, has been used as an experimental technique for the basic study of fracture. Examples of the use of acoustic emission for this latter purpose are reviewed, and future research opportunities identified. 37483
Sachse, W.
Applications of quantitative AE methods: Dynamic fracture, materials and transducer characterization Solid Mechanics Research for Q ua nt i t a t i ve Nondestructive Evaluation, Proceedings of the O N R Symposium on Solid Mechanics Research for Q N D E , Northwestern University, Eva n s to n , Illinois (United States), 18-20 Sep. 1985 pp. 41-66. Martinus Nijhoff Publishers (1987) This paper summarizes the applications of quantitative acoustic emission (AE) measurements for investigation of dynamic fracture processes and for the characterization of materials and transducers. The basis of the technique is a measurement system in which two of the three components comprising it (source, structure, sensor) have known temporal and spatial characteristics such that the temporal and spatial features of the third component can be recovered by appropriate signal processing methods. Examples presented in this paper include the characterization of cracks in brittle materials, the evaluation of the frequency-dependent attenuation and dispersion in absorptive composite materials and the determination of the apperture effect of a detecting transducer. 37481
Electric Power Research Institute
Comparative evaluation of acoustic holography systems Electric Power Research Institute, Palo Alto, California (United States), EPRI-NP-5130, 60 pp. (Apr. 1987) Utilities are considering the use of acoustic holography systems to size flaws in metal components of nuclear power plants. System limitations, however, could lead to serious over- or underestimation of flaw sizes. This project evaluated two acoustic holography systems and made suggestions for improving flaw-sizing accuracy. 37480
Jha, B.B.; Khanna, A.S.; Raj, B.
Study of the oxidation behaviour of 9Cr-1 Mo steel using the acoustic emission technique Journal of Materials Science, Vol. 22, No. 8, pp. 2823-2827 (Aug. 1987) The onset of breakaway oxidation and in situ cracking of the oxide formed on 9Cr-1 Mo steel in air at 900 and 950C has been detected by an acoustic emission (AE) technique. AE parameters, i.e. AE counts and AE event counts, show negligible increase during isothermal heating at thege temperatures, until a point is reached where a sudden increase in AE activity is found, This point corresponds to the onset of breakaway oxidation. An enormous increase in AE
133
Carpenter, S.H.; Armstrong, J.; Heiple, C.R.
Detection of hydrogen-assisted crack growth by measurement of modulus changes and acoustic emission Corrosion Monitoring in Industrial Plants using Nondestructive Testing and Electrochemical Methods. A symposium sponsored by A S T M C o m m i t t e e E-7 on Nondestructive Testing and C o m m i t t e e G-1 on Corrosion of Metals, Montreal, Canada, 22-24 May 1984. pp. 165-178. A S T M Special Technical Publication 908 An investigationof new techniques to probe and study the initiation of cracks in a hydrogen environment is reported. The techniques investigated are the precise continuous measurement of changes in the elastic modulus and acoustic emission measurements. A decrease in the elastic modulus should be observed as cracks nucleate and grow in a test material. Measurements of changes in the elastic modulus while cathodically charging a number of iron base materials both at zero load and under applied load are also given. In all cases a decrease in the elastic modulus was observed as a result of cathodic charging with hydrogen. The modulus loss was found to be permanent and could not be restored by heat treatment. Acoustic emission measurement were carried out as miniature pressure vessels were pressurized and subsequently held at pressure. Differences in the acoustic emission were observed for vessels pressurized with hydrogen gas as compared to vessels pressurized with helium. Considerably more acoustic emission was generated in vessels pressurized with hydrogen. 37686
Martin, P.; Dickson, J.L; Bailon, J.-P.
Monitoring stress-corrosion cracking by acoustic emission Corrosion Monitoring in Industrial Plants using Nondestructive Testing and Electrochemical Methods. A symposium sponsored by A S T M C o m m i t t e e E-7 on Nondestructive Testing and C o m m i t t e e G-1 on Corrosion of Metals, Montreal, Canada, 22-24 May 1984. pp. 75-88. A S T M Special Technical Publication 908 Acoustic emission (AE) is well suited for laboratory studies of stress corrosion cracking (SCC) since the crack velocity is often approximately proportional to the AE rate. For 7075-T651 and 2024-T351 aluminum alloys, this proportionality is shown to be particularly good. For 7075-T651, less scatter is obtained in SCC crack velocity when these are based on the cumulative AE counts than on surface crack length measurements. The curve of AE rate versus time after addition of fresh solution into the crack depends on the type of transducer employed. Using either a broad-band or a resonant transducer, it was possible to distinguish between SCC and corrosion signals from their frequency spectrum. The applicability of employing AE to detect SCC in an industrial environment is considered. Possible solutions to some of the difficulties expected in cases where SCC produces low-amplitude AE signals are discussed. 37685
Yuyama, S.
Fundamental aspects of acoustic emission applications to the problems caused by corrosion Corrosion Monitoring in Industrial Plants using Nondestructive Testing and Electrochemical Methods. A symposium sponsored by A S T M C o m m i t t e e E-7 on Nondestructive Testing and C o m m i t t e e G-1 on Corrosion of Metals, Montreal, Canada, 22-24 May 1984. pp. 43-74. A S T M Special Technical Publication 908 This paper describes the use of acoustic emission (AE) for the detection and monitoring of corrosion, stress corrosion cracking (SCC), and corrosion fatigue (CF). It surveys laboratory studies and field applications that have been made to date. The application of the technique to fundamental studies in the laboratory and continuous monitoring in engineering structures are discussed in detail. Various microprocesses that can produce detectable AE are shown and their relative energy levels, emanated as AE, are discussed in terms of peak amplitudes measured on laboratory specimens by a conventional piezoelectric sensor.
37684
Pollock, A.A.
Acoustic emission capabilities and applications in monitoring corrosion Corrosion Monitoring in Industrial Plants using Nondestructive Testing and Electrochemical Methods. A symposium sponsored by A S T M C o m m i t t e e E-7 on Nondestructive Testing and C o m m i t t e e G-1 on Corrosion of Metals, Montreal, Canada, 22-24 May 1984. pp. 30-42. A S T M Special Technical Publication 908 The physical processes of corrosion are examined as possible sources of acoustic emission (AE). Detectable emission is produced by film cracking, gas evolution, hydrogen-induced microcracking, plastic zone growth, and discontinuous crack movements in stress-corrosion cracking (SCC) and
NDT International April 1989
hydrogen-assisted cracking. By these mechanisms corrosion can be detected while it is occurring. Practical applications include rapid evaluation of the susceptibility of materials to corrosion, particularly to SCC. Apart from real-time monitoring of the corrosion process, the structural damage caused by corrosion can be detected after it has occured by AE monitoring during application of stress. In this testing mode, emission is enhanced by surface degradation and corrosion products. Pipelines and aircraft structures have been tested in this way. In large structures it is generally more practical to detect the results of corrosion than to monitor the corrosion process itself. For success in field applications attention must be paid to issues such as background noise and wave attenuation, and operator training and experience is an important factor. 37680
Kim, K.H.; Kishi, T.
Three dimensional AE source location in metals Nondestructive Testing C ommuni c a t i ons , Vol. 3, No. 3, pp. 75-88 (1987) An acoustic wave emitted.from microcracks or inclusions was detected by six transducers mounted on the specimen, then amplified and digitized by a highly efficient wave memory system. Three dimensional location of defects was carried out using, 3 types of Ti alloys, A533B steel, and A470 steel. Differences in the tendency to form microcracks in different fracture modes was confirmed. 37485
Ivanov, V.L; Kuranov, V.N.; Ryabov, A.N.
Acoustic emission in low-cyclic fatigue Soviet Physics D okl a dy, Vol. 31, No. 6, pp. 517-518 (Jun. 1986) Well established theory and experimental data are used to develop a model of fatigue-crack growth (FCG). Pulsed elastic waves are emitted from a strain resistant but brittle material embedded in a material still prone to plastic deformation when the brittle material is caused to increase in volume. In addition to this acoustic emission, a crack is found to jump along the boundary of the two materials. A physically well defined parameter, easily verified experimentally is proposed to estimate the growth rate of fatigue cracks. 37484
Wadley, H.N.G.
Acoustic emission: A quantitative NDE technique for the study of fracture Solid Mechanics Research for Q ua nt i t a t i ve Nondestructive Evaluation, Proceedings of the O N R Symposium on Solid Mechanics Research for Q N D E , Northwestern University, Evanston, Illinois (United States), 18-20 Sep. 1985 pp. 25-40. Martinus Nijhoff Publishers (1987) Acoustic emission, an NDE technique that shows promise for detecting and locating cracks in engineering structures, has been used as an experimental technique for the basic study of fracture. Examples of the use of acoustic emission for this latter purpose are reviewed, and future research opportunities identified. 37483
Sachse, W.
Applications of quantitative AE methods: Dynamic fracture, materials and transducer characterization Solid Mechanics Research for Q ua nt i t a t i ve Nondestructive Evaluation, Proceedings of the O N R Symposium on Solid Mechanics Research for Q N D E , Northwestern University, Eva n s to n , Illinois (United States), 18-20 Sep. 1985 pp. 41-66. Martinus Nijhoff Publishers (1987) This paper summarizes the applications of quantitative acoustic emission (AE) measurements for investigation of dynamic fracture processes and for the characterization of materials and transducers. The basis of the technique is a measurement system in which two of the three components comprising it (source, structure, sensor) have known temporal and spatial characteristics such that the temporal and spatial features of the third component can be recovered by appropriate signal processing methods. Examples presented in this paper include the characterization of cracks in brittle materials, the evaluation of the frequency-dependent attenuation and dispersion in absorptive composite materials and the determination of the apperture effect of a detecting transducer. 37481
Electric Power Research Institute
Comparative evaluation of acoustic holography systems Electric Power Research Institute, Palo Alto, California (United States), EPRI-NP-5130, 60 pp. (Apr. 1987) Utilities are considering the use of acoustic holography systems to size flaws in metal components of nuclear power plants. System limitations, however, could lead to serious over- or underestimation of flaw sizes. This project evaluated two acoustic holography systems and made suggestions for improving flaw-sizing accuracy. 37480
Jha, B.B.; Khanna, A.S.; Raj, B.
Study of the oxidation behaviour of 9Cr-1 Mo steel using the acoustic emission technique Journal of Materials Science, Vol. 22, No. 8, pp. 2823-2827 (Aug. 1987) The onset of breakaway oxidation and in situ cracking of the oxide formed on 9Cr-1 Mo steel in air at 900 and 950C has been detected by an acoustic emission (AE) technique. AE parameters, i.e. AE counts and AE event counts, show negligible increase during isothermal heating at thege temperatures, until a point is reached where a sudden increase in AE activity is found, This point corresponds to the onset of breakaway oxidation. An enormous increase in AE
133