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Nov 1978

Volume 64, Issue S1, pp. S1-S183

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back to top Session LLL. Physical Acoustics X: Acoustic Emission II
Invited Papers
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AE behavior of various materials (A)

Hiroyasu Nakasa

J. Acoust. Soc. Am. Volume 64, Issue S1, pp. S174-S174 (1978); (1 page)

Online Publication Date: 11 Aug 2005

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To apply the AE techniques to the structural integrity monitor in many industrial areas, it is necessary to get a good understanding on the AE behavior of the structural materials and to accumulate basic reference data related to various modes of failure. The AE behavior is strongly affected by both the material inherent nature and the external conditions such as stress, temperature and the surrounding atmosphere. AE event‐rate and peak‐amplitude‐distribution characteristics, which are the best indicators of the AE activities for first arrival signals entered into a selected transducer, are summarized in the process of uniaxial tension and/or compression loading for various industrial materials of steels, nonferrous metals, and nonmetals. The changes of the AE activities are also presented from the sound state to the degraded state followed by neutron irradiation, strain‐aging, thermal degradation, corrosion, fatigue, etc.
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Acoustic emission arising from plastic deformation and fracture (A)

Kanji Ono

J. Acoust. Soc. Am. Volume 64, Issue S1, pp. S174-S175 (1978); (2 pages)

Online Publication Date: 11 Aug 2005

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This paper reviews diverse observations of acoustic emission from materials and attempts to interpret them on the basis of current knowledge of plastic deformation and fracture. An attempt is made to unify diverse and often conflicting findings paying special attention to microstructural conditions. Observed acoustic emission characteristics have been classified according to their probable origins such as heterogeneous and homogeneous yielding, dynamic strain aging, twinning, decoheston and fracture of second phase particles, and deformation‐induced transformation. Temperature effects and sources of burst‐type emissions are considered. The micro‐yielding concept and other mechanisms are correlated to various acoustic emission behavior observed. Fracture processes generally produce high levels of acoustic emission. Various fracture mechanisms found in different classes of materials are correlated to observed acoustic emission behavior. Relationships between different AE parameters and stress intensity factor or crack tip opening displacement are discussed. It is shown that the consideration of second phase particles is of crucial importance in identifying the mechanisms of acoustic emission. [Work supported by ONR.]
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Deformation and failure information from composite materials via acoustic emission (A)

M. A. Hamstad

J. Acoust. Soc. Am. Volume 64, Issue S1, pp. S175-S175 (1978); (1 page)

Online Publication Date: 11 Aug 2005

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An introductory literature review of the applications of acoustic emission (AE) to the study of composite materials and structures is given. This survey demonstrates the unique information that AE provides on the deformation and fracture processes which occur when composite materials are stressed. Also included in the review is a survey of the application of AE to nondestructive testing of composite materials. Following the review, new research results are presented in some areas of current research interest. The following areas are emphasized: (1) Wave propagation complications and the development of AE source location techniques in Kevlar 49/Epoxy composite pressure vessels; (2) evaluation of a special immersion type AE transducer; (3) study of couplants for AE testing of composites; and (4) application of AE to the study of a Boron/Aluminum particulate composite. [Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore Laboratory under contract No. W‐7405‐ENG‐48.]
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Application of acoustic emission in the geotechnical area (A)

R. M. Koerner and A. E. Lord, Jr.

J. Acoust. Soc. Am. Volume 64, Issue S1, pp. S175-S175 (1978); (1 page)

Online Publication Date: 11 Aug 2005

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A review of the application of acoustic emission (microseismic) techniques to the geotechnical area will be given. The approach will be somewhat historical starting with the pioneering work (in the 1930's) by Obert and Duvall in the coal and metal mines and continuing up to the present where currently a host of materials and engineering problems are being investigated with acoustic emission techniques. Acoustic emission measurements in the laboratory will be described which have given insight into the mechanical behavior of rocks, soils, coal and ice. Field applications which will be dealt with include determination of the stability of mine tunnels, open pit mine slopes, underground gas storage reservoirs, and earthem dikes and dams. The use of acoustic emission techniques in earthquake prediction studies will be reviewed. [The authors' work has been supported by EPA.]
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Acoustic emission characteristics during magnetization of ferromagnetic materials (A)

H. Kusanagi, H. Kimura, and H. Sasaki

J. Acoust. Soc. Am. Volume 64, Issue S1, pp. S175-S175 (1978); (1 page)

Online Publication Date: 11 Aug 2005

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The characteristics of acoustic emission generated during magnetization of typical ferromagnetic materials (steel, nickel, and cobalt) in alternating magnetic field of 50 Hz were investigated. Acoustic emission parameters measured were root‐mean‐square voltage, frequency spectrum, and waveform. The data were taken as a function of stress, magnetic field strength, and annealing time. It became clear that the magnitudes of acoustic emission during magnetization of steel and nickel were strongly dependent on stress and the features of these stress dependencies changed with magnetic field strength. It was found that the magnitude of acoustic emission during magnetization of cobalt was much smaller than those of steel and nickel. This experimental result and the theoretical calculation of elastic energy emitted by domain wall motion show that the motion of 90° domain wall is the most probable source for the acoustic emission during magnetization of ferromagnetic materials.
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