Elastic wave emission from damage processes

The theory of elastic wave emission (i.e., acoustic emission; AE) from damage processes such as slip and microcracking is discussed. Analogous developments in the literature on earth-quake seismology and dynamic dislocation theory are noted and utilized. A general representation of the displacement field of an AE event is given in terms of the double-couple response to a distribution of “moment density tensor” in the source region. Results are specialized to a point source model and to a general far-field analysis of outgoing elastic waves, and conditions for validity of such representations and their low-frequency specializations are noted. Emitted wave fields are compared for tensile opening and slip events, and procedures which might enable the approximate determination of the size or area increase of tensile microcracks are discussed.

[1]  S. Hartzell,et al.  Far‐field S‐wave spectra, corner frequencies, and pulse shapes , 1979 .

[2]  George E. Backus,et al.  Moment Tensors and other Phenomenological Descriptions of Seismic Sources—I. Continuous Displacements , 1976 .

[3]  C. B. Scruby,et al.  Quantitative acoustic emission source characterisation during low temperature cleavage and intergranular fracture , 1981 .

[4]  Yih-Hsing Pao.  Elastic waves and non-destructive testing of materials : [papers] presented at the winter annual meeting of the American Society of Mechanical Engineers, San Francisco, California, December 10-15, 1978 , 1978 .

[5]  P. Richards.  The dynamic field of a growing plane elliptical shear crack , 1973 .

[6]  Paul G. Richards,et al.  Dynamic motions near an earthquake fault: a three dimensional solution , 1976 .

[7]  Leon Knopoff,et al.  Body Force Equivalents for Seismic Dislocations , 1964 .

[8]  K. Malén,et al.  A Theoretical Estimate of Acoustic-Emission Stress Amplitudes , 1974, February 1.

[9]  Keiiti Aki,et al.  Fault plane with barriers: A versatile earthquake model , 1977 .

[10]  Raul Madariaga,et al.  High-frequency radiation from crack (stress drop) models of earthquake faulting , 1977 .

[11]  R. Madariaga.  Dynamics of an expanding circular fault , 1976, Bulletin of the Seismological Society of America.

[12]  H. Herman.  Advances in materials research , 1967 .

[13]  N. A. Haskell.  Total energy and energy spectral density of elastic wave radiation from propagating faults , 1964 .

[14]  J. Christensen.  Doctoral thesis , 1970 .