- Email: [email protected]
Study of the oxidation behaviour of 9Cr-1 Mo steel using the acoustic emission technique
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
activity after the start of cooling has been attributed to the separation of scale from matrix as a result of thermal stresses arising during cooling. Peak amplitude distribution is measured and b values are calculated. These are both used to" distinguish between the phenomenon at 900 and 950C in terms of the amplitudes of the AE emission released. 37478
Rogers, L.M.
The detection and monitoring of cracks in structures, process vessels and pipework by acoustic emission H a z a r d s in the p r o c e s s industries: H a z a r d s IX, a t h r e e - d a y s y m p o s i u m o r g a n i z e d by T h e I n s t i t u t i o n of C h e m i c a l E n g i n e e r s ( N o r t h W e s t e r n B r a n c h ) , U n i v e r s i t y of M a n c h e s t e r I n s t i t u t e for Science and T e c h n o l o g y ( U n i t e d K i n g d o m ) , 2-4 A p r . 1986, pp. 201-214. T h e I n s t i t u t i o n of C h e m i c a l E n g i n e e r s S y m p o s i u m Series No. 97 Acoustic Emission monitoring of low fatigue life joints and defective weldments on offshore structures is providing new insight into the mechanism of fatigue crack propagation in these structures and strong evidence of the reliability of the method for the remote detection and monitoring of cracks. Results obtained during 1984/85 on three offshore structures are presented and compared with data from laboratory tests on large scale weldments. Hitherto problems with the sub-sea installation of transducers, background noise, data condensation, equipment supervision and operational reliability have been solved by the development of new measurement and analysis instrumentation. The equipment is described. 37477
Scruby, C.B.; Stacey, K.A.
Acoustic emission measurements of PWR weld material with inserted defects United Kingdom Atomic Energy Authority, Harwell, AERE-R12386, 39 pp. (Jan. 1987) Ten specimens of A533B pressure vessel steel containing realistic welding defects have been monitored for acoustic emission during monotonic loading. The detection system consisted of an array of four point-contact broad-band transducers whose outputs were fed via broad- band amplifiers into a multi-channel digital recording system. Specimens containing cracks, slag inclusions and porosity all generated copious emission over a range of loads, while defect-free specimens only emitted when general yield had been reached. Three-dimensional location techniques have been used to "image" the different types of defect and show how the concentration of stress, as evidenced by emission activity, moved to different regions of the defect during testing. Only limited analysis using source radiation patterns was possible, which confirmed the events to have broadly the character of mode I crack opening. 37270
Kumosa, M.
Acoustic emission monitoring of stress corrosion cracks in aligned GRP J o u r n a l of Physics D , Vol. 20, No. 1, (14 Jan. 1987) The growth of stress corrosion cracks in aligned glass-reinforced polyester resin was monitored using the acoustic emission technique. The cracks propagated perpendicularly to the fibre direction under very low stress levels. The log-normal distribution function was applied to describe peak amplitude distributions of the acoustic emission signals produced mainly by fibre failure. It was found that the average peak amplitude of the signals is a linear function of the stress intensity K at the stress corrosion crack tip. 37269
Hutton, P.H.; Friesel, M.A.; Kurtz, R.J.
Progress for on-line acoustic emission monitoring of cracks in reactor systems P r o c e e d i n g s of the U.S. N u c l e a r R e g u l a t o r y C o m m i s s i o n F o u r t e e n t h W a t e r R e a c t o r Safety I n f o r m a t i o n M e e t i n g : Vol. 2, G a i t h e r s b u r g , M a r y l a n d ( U n i t e d S t a t e s ) , 27-31 Oct. 1986. pp. 43-55 N U R E G CP-0082, 438 pp. (Feb. 1987) This paper discusses program activities to develop "Acoustic Emission/Flaw Relationships for Inservice Monitoring of LWRs'. The work is sponsored by the NRC Research Office with TVA currently providing supplemental funding. Accomplishments for FY86 and plans for FY87 are reviewed under the topics of reactor monitoring, A E signal pattern recognition, IGSCC/AE relationships, and standards and code work. Current program emphasis is on technology transfer including validating the technology on-reactor and establishing the technology in national standards and codes. 37264
Bartenev, O.A.; Zabil'skii, V.V.; Veliehko, V.V.
Acoustic emission recording of the initiation and kinetics of intercrystalline crack growth I n d u s t r i a l L a b o r a t o r y , Vol. 52, No. 10, pp. 953-955 ( A p r . 1987) High-strength steels with the structure of martensite produced by quenching or low-temperature tempering are characterized by increased susceptibility to delayed failure. It is assumed that delayed failure is caused by the initiation and slow growth of a brittle intercrystalline crack in holding under load in the macroelastic region. In the present work, we used the acoustic emission (AE) method in delayed failure tests on 40KhG medium-carbon steel after quenching in oil (HRC 52-55) to detect the incubation period of crack initiation and construct kinetic acoustic emission diagrams characterizing the size of the growing delayed failure crack. The high rate of brittle failure leads to high-energy acoustic emission of the explosion type (discrete AE) so that the method can be used in recording the early stages of delayed failure which cannot be controlled by means of the mechanical properties. 37260
Yukuan, M.
Effect on flaw location by the wave shape of acoustic emission propagating in a limited medium
134
l l t h W o r l d C o n f e r e n c e o n N o n d e s t r u c t i v e Testing, Las Vegas, N e v a d a ( U n i t e d States), 3-8 Nov. 1985. Vol. 1, pp. 62-69. T a y l o r Publishing C o . , D a l l a s (1985). Because of the factors of frequency dispersion, attenuation and interface reflection and so on, the A E waves are seriously distorted, i.e. the function of the original wave is affected by system transfer function. Different positions, to which the same signal of a source is emitted, have different A E waves detected, causing measurement errors of propagating velocities, and therefore a large error in location. In this paper, changes in propagating waves, at observational points, with time and space are analysed and a way to overcome the error from the distortion in flaw location is given. 37258
Vincenzo, D.R.; Bruno, B.; Franco, C.
Defect detection in stainless steel 'Uranus 45' T I G welded joints by acoustic emission l l t h W o r l d C o n f e r e n c e on N o n d e s t r u c t i v e Testing, Las Vegas, N e v a d a ( U n i t e d States), 3-8 Nov. 1985. Vol. 1, pp. 85-90. T a y l o r Publishing C o . , D a l l a s (1985). The aim of this research is to evaluate the applicability of A.E. technique to defect detection in TlG-welded thin plates of 'Uranus 45' (X2CrNiMoN225) stainless steel, used for the tanks of the European rocket 'Ariane'. The results of the first tests performed on two sheets of different chemical composition and mechanical properties, are reported in this paper. The analysed defects are: notches, holes, porosity and tungsten inclusions. The tests have been carried out up to failure of the specimens, but only the A.E. results obtained up to the stress level corresponding to the hydraulic test of the tank (sigma = 506 MPa) have been analysed. 37253
Banov, M.D.; Troenkin, D.A.; Urbakh, A.I.; Minatsevich,
S.F. Inspection of the condition of gas-turbine engine blades by the acoustic-emission method Soviet J o u r n a l of N o n d e s t r u c t i v e Testing, Vol. 22, No. 9, pp. 619-623 ( M a y 1987) The results arc presented of investigations of the use of acoustic emission for testing of the cooled blades of gas-turbine engines. The possibility of revealing defects in the internal cavities of the blades at stresses not exceeding those in service is shown. 37244
Caldwell, D.L.; Steele, D.L.; Guth, L.T.
Optimization of composite matrices using acoustic emission analysis J o u r n a l of R e i n f o r c e d Plastics a n d C o m p o s i t e s , Vol. 6, No. 2, pp. 193206 ( A p r . 1987) Unidirectional glass-reinforced laminates were prepared from nine resin systems. A set of standardized tests was used in combination with acoustic emission analysis (AEA) to determine the suitability of the resins for composites applications. 36991
Storch, W.; Ruf, H.; Scholze, H.
Basic principles for testing ceramic-bonded grinding wheels by acoustic emission analysis (In German) C e r a m i c F o r u m I n t e r n a t i o n a l , Vol.64, No. 1/2. pp. 18,22 ( J a n . / F e b . 1987) Newly manufactured grinding wheels are subjected to quality control inspections which involve the determination of Young,s modulus and hardness values. In addition, wheels must also pass an overspeed test at velocities ranging from 1.1 to 1.5 times the normal in-service circumferential velocity. However, such overspeed testing contains the risk that cracks formed during a test could reduce the strength of the wheel under service load conditions. With a view to minimizing that risk, it was decided to investigate the extent to which strengthreducing cracks can be detected by acoustic emission analysis, in order to develop a better method of testing grinding wheels. 36990
Sachse, W.; Kim, K.Y.; Chen, C.P.
Studies of acoustic emission from point and extended sources A n a l y t i c a l U l t r a s o n i c s in M a t e r i a l s R e s e a r c h a n d Testing. P r o c e e d i n g s of a c o n f e r e n c e , N A S A L e w i s R e s e a r c h C e n t e r , O h i o ( U n i t e d States), 13- 14 Nov. 1984. pp. 49-59. N A S A C o n f e r e n c e P u b l i c a t i o n 2383 (1986). The use of simulated and controlled acoustic emission signals forms the basis of a powerful tool for the detailed study of various deformation and wave interaction processes in materials. We report the results of experiments and signal analyses of A E resulting from point sources such as various types of indentation-produced cracks in brittle materials and the growth of fatigue cracks in 7075-T6 aluminum panels. Furthermore, we describe our recent work dealing with the modeling and subsequent signal processing of an extended source of emission in a material. Results of the forward problem and the inverse problem are presented with the example of a source distributed through the interior of a specimen shown. 36979
Anon
Sandia uses computer models to study crack damage in brittle materials C e r a m i c B u l l e t i n , Vol. 66, No. 1, p. 39 (1987) The complex processes that govern stress-induced crack damage in brittle materials have been investigated by analysing the intensity and frequency of acoustic emissions emitted as microcracking occurs.
NDT International April 1989
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
activity after the start of cooling has been attributed to the separation of scale from matrix as a result of thermal stresses arising during cooling. Peak amplitude distribution is measured and b values are calculated. These are both used to" distinguish between the phenomenon at 900 and 950C in terms of the amplitudes of the AE emission released. 37478
Rogers, L.M.
The detection and monitoring of cracks in structures, process vessels and pipework by acoustic emission H a z a r d s in the p r o c e s s industries: H a z a r d s IX, a t h r e e - d a y s y m p o s i u m o r g a n i z e d by T h e I n s t i t u t i o n of C h e m i c a l E n g i n e e r s ( N o r t h W e s t e r n B r a n c h ) , U n i v e r s i t y of M a n c h e s t e r I n s t i t u t e for Science and T e c h n o l o g y ( U n i t e d K i n g d o m ) , 2-4 A p r . 1986, pp. 201-214. T h e I n s t i t u t i o n of C h e m i c a l E n g i n e e r s S y m p o s i u m Series No. 97 Acoustic Emission monitoring of low fatigue life joints and defective weldments on offshore structures is providing new insight into the mechanism of fatigue crack propagation in these structures and strong evidence of the reliability of the method for the remote detection and monitoring of cracks. Results obtained during 1984/85 on three offshore structures are presented and compared with data from laboratory tests on large scale weldments. Hitherto problems with the sub-sea installation of transducers, background noise, data condensation, equipment supervision and operational reliability have been solved by the development of new measurement and analysis instrumentation. The equipment is described. 37477
Scruby, C.B.; Stacey, K.A.
Acoustic emission measurements of PWR weld material with inserted defects United Kingdom Atomic Energy Authority, Harwell, AERE-R12386, 39 pp. (Jan. 1987) Ten specimens of A533B pressure vessel steel containing realistic welding defects have been monitored for acoustic emission during monotonic loading. The detection system consisted of an array of four point-contact broad-band transducers whose outputs were fed via broad- band amplifiers into a multi-channel digital recording system. Specimens containing cracks, slag inclusions and porosity all generated copious emission over a range of loads, while defect-free specimens only emitted when general yield had been reached. Three-dimensional location techniques have been used to "image" the different types of defect and show how the concentration of stress, as evidenced by emission activity, moved to different regions of the defect during testing. Only limited analysis using source radiation patterns was possible, which confirmed the events to have broadly the character of mode I crack opening. 37270
Kumosa, M.
Acoustic emission monitoring of stress corrosion cracks in aligned GRP J o u r n a l of Physics D , Vol. 20, No. 1, (14 Jan. 1987) The growth of stress corrosion cracks in aligned glass-reinforced polyester resin was monitored using the acoustic emission technique. The cracks propagated perpendicularly to the fibre direction under very low stress levels. The log-normal distribution function was applied to describe peak amplitude distributions of the acoustic emission signals produced mainly by fibre failure. It was found that the average peak amplitude of the signals is a linear function of the stress intensity K at the stress corrosion crack tip. 37269
Hutton, P.H.; Friesel, M.A.; Kurtz, R.J.
Progress for on-line acoustic emission monitoring of cracks in reactor systems P r o c e e d i n g s of the U.S. N u c l e a r R e g u l a t o r y C o m m i s s i o n F o u r t e e n t h W a t e r R e a c t o r Safety I n f o r m a t i o n M e e t i n g : Vol. 2, G a i t h e r s b u r g , M a r y l a n d ( U n i t e d S t a t e s ) , 27-31 Oct. 1986. pp. 43-55 N U R E G CP-0082, 438 pp. (Feb. 1987) This paper discusses program activities to develop "Acoustic Emission/Flaw Relationships for Inservice Monitoring of LWRs'. The work is sponsored by the NRC Research Office with TVA currently providing supplemental funding. Accomplishments for FY86 and plans for FY87 are reviewed under the topics of reactor monitoring, A E signal pattern recognition, IGSCC/AE relationships, and standards and code work. Current program emphasis is on technology transfer including validating the technology on-reactor and establishing the technology in national standards and codes. 37264
Bartenev, O.A.; Zabil'skii, V.V.; Veliehko, V.V.
Acoustic emission recording of the initiation and kinetics of intercrystalline crack growth I n d u s t r i a l L a b o r a t o r y , Vol. 52, No. 10, pp. 953-955 ( A p r . 1987) High-strength steels with the structure of martensite produced by quenching or low-temperature tempering are characterized by increased susceptibility to delayed failure. It is assumed that delayed failure is caused by the initiation and slow growth of a brittle intercrystalline crack in holding under load in the macroelastic region. In the present work, we used the acoustic emission (AE) method in delayed failure tests on 40KhG medium-carbon steel after quenching in oil (HRC 52-55) to detect the incubation period of crack initiation and construct kinetic acoustic emission diagrams characterizing the size of the growing delayed failure crack. The high rate of brittle failure leads to high-energy acoustic emission of the explosion type (discrete AE) so that the method can be used in recording the early stages of delayed failure which cannot be controlled by means of the mechanical properties. 37260
Yukuan, M.
Effect on flaw location by the wave shape of acoustic emission propagating in a limited medium
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l l t h W o r l d C o n f e r e n c e o n N o n d e s t r u c t i v e Testing, Las Vegas, N e v a d a ( U n i t e d States), 3-8 Nov. 1985. Vol. 1, pp. 62-69. T a y l o r Publishing C o . , D a l l a s (1985). Because of the factors of frequency dispersion, attenuation and interface reflection and so on, the A E waves are seriously distorted, i.e. the function of the original wave is affected by system transfer function. Different positions, to which the same signal of a source is emitted, have different A E waves detected, causing measurement errors of propagating velocities, and therefore a large error in location. In this paper, changes in propagating waves, at observational points, with time and space are analysed and a way to overcome the error from the distortion in flaw location is given. 37258
Vincenzo, D.R.; Bruno, B.; Franco, C.
Defect detection in stainless steel 'Uranus 45' T I G welded joints by acoustic emission l l t h W o r l d C o n f e r e n c e on N o n d e s t r u c t i v e Testing, Las Vegas, N e v a d a ( U n i t e d States), 3-8 Nov. 1985. Vol. 1, pp. 85-90. T a y l o r Publishing C o . , D a l l a s (1985). The aim of this research is to evaluate the applicability of A.E. technique to defect detection in TlG-welded thin plates of 'Uranus 45' (X2CrNiMoN225) stainless steel, used for the tanks of the European rocket 'Ariane'. The results of the first tests performed on two sheets of different chemical composition and mechanical properties, are reported in this paper. The analysed defects are: notches, holes, porosity and tungsten inclusions. The tests have been carried out up to failure of the specimens, but only the A.E. results obtained up to the stress level corresponding to the hydraulic test of the tank (sigma = 506 MPa) have been analysed. 37253
Banov, M.D.; Troenkin, D.A.; Urbakh, A.I.; Minatsevich,
S.F. Inspection of the condition of gas-turbine engine blades by the acoustic-emission method Soviet J o u r n a l of N o n d e s t r u c t i v e Testing, Vol. 22, No. 9, pp. 619-623 ( M a y 1987) The results arc presented of investigations of the use of acoustic emission for testing of the cooled blades of gas-turbine engines. The possibility of revealing defects in the internal cavities of the blades at stresses not exceeding those in service is shown. 37244
Caldwell, D.L.; Steele, D.L.; Guth, L.T.
Optimization of composite matrices using acoustic emission analysis J o u r n a l of R e i n f o r c e d Plastics a n d C o m p o s i t e s , Vol. 6, No. 2, pp. 193206 ( A p r . 1987) Unidirectional glass-reinforced laminates were prepared from nine resin systems. A set of standardized tests was used in combination with acoustic emission analysis (AEA) to determine the suitability of the resins for composites applications. 36991
Storch, W.; Ruf, H.; Scholze, H.
Basic principles for testing ceramic-bonded grinding wheels by acoustic emission analysis (In German) C e r a m i c F o r u m I n t e r n a t i o n a l , Vol.64, No. 1/2. pp. 18,22 ( J a n . / F e b . 1987) Newly manufactured grinding wheels are subjected to quality control inspections which involve the determination of Young,s modulus and hardness values. In addition, wheels must also pass an overspeed test at velocities ranging from 1.1 to 1.5 times the normal in-service circumferential velocity. However, such overspeed testing contains the risk that cracks formed during a test could reduce the strength of the wheel under service load conditions. With a view to minimizing that risk, it was decided to investigate the extent to which strengthreducing cracks can be detected by acoustic emission analysis, in order to develop a better method of testing grinding wheels. 36990
Sachse, W.; Kim, K.Y.; Chen, C.P.
Studies of acoustic emission from point and extended sources A n a l y t i c a l U l t r a s o n i c s in M a t e r i a l s R e s e a r c h a n d Testing. P r o c e e d i n g s of a c o n f e r e n c e , N A S A L e w i s R e s e a r c h C e n t e r , O h i o ( U n i t e d States), 13- 14 Nov. 1984. pp. 49-59. N A S A C o n f e r e n c e P u b l i c a t i o n 2383 (1986). The use of simulated and controlled acoustic emission signals forms the basis of a powerful tool for the detailed study of various deformation and wave interaction processes in materials. We report the results of experiments and signal analyses of A E resulting from point sources such as various types of indentation-produced cracks in brittle materials and the growth of fatigue cracks in 7075-T6 aluminum panels. Furthermore, we describe our recent work dealing with the modeling and subsequent signal processing of an extended source of emission in a material. Results of the forward problem and the inverse problem are presented with the example of a source distributed through the interior of a specimen shown. 36979
Anon
Sandia uses computer models to study crack damage in brittle materials C e r a m i c B u l l e t i n , Vol. 66, No. 1, p. 39 (1987) The complex processes that govern stress-induced crack damage in brittle materials have been investigated by analysing the intensity and frequency of acoustic emissions emitted as microcracking occurs.
NDT International April 1989