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Dynamic Photoelastic Studies of P and S Wave Propagation in Prestressed Media

Thomson, Ker C. and Ahrens, Thomas J. and Toksöz, M. Nafi (1969) Dynamic Photoelastic Studies of P and S Wave Propagation in Prestressed Media. Geophysics, 34 (5). pp. 696-712. ISSN 0016-8033.

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The occasional existence of very pronounced, anomalous, horizontally polarized seismic waves from underground nuclear bomb blasts has been reported by several investigators. In order to further understanding of this phenomenon and the processes of mechanical radiation from explosions, particularly in prestressed media, a model study has been undertaken. Experimental apparatus has been developed which permits the generation and propagation of body waves from explosions in transparent plate models prestressed to various two-dimensional stress configurations. High-speed framing camera sequences are presented showing the explosion process and the resulting plate compressional and shear wave propagation in prestressed models. These are compared to theoretical calculations of isochromatic and π/4 isoclinic fringe patterns associated with the wave propagation in stress-free plates and plates prestressed in tension and shear. The following distinctive optical phenomena were predicted theoretically and observed in the high-speed photoelastic patterns: a π/4 discontinuity between P and S wave isoclinics for the unstressed case; a tendency for the isoclinics to broaden and envelope the isochromatics in regions where the P and S waves are superimposed; development of serrations in the dynamic isoclinics in the presence of a prestressing field (yielding a pseudo-isochromatic appearance to isoclinics when viewed monochromatically); and finally, a general similarity between the dynamic optical effects in media under tensile and shear prestress.

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Additional Information:© 1969 by the Society of Exploration Geophysicists. Manuscript received by the Editor September 26, 1968; revised manuscript received April 7, 1969. This research was funded jointly by the Advanced Research Projects Agency and the Air Force Cambridge Research Laboratories. Much of the experimental work was done at Stanford Research Institute.
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Advanced Research Projects Agency (ARPA)UNSPECIFIED
Air Force Cambridge Research LaboratoriesUNSPECIFIED
Issue or Number:5
Record Number:CaltechAUTHORS:20151120-085359033
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Official Citation:Ker C. Thomson, Thomas J. Ahrens, and M. Nafi Toksoz A. Grover Discussion on "Dynamic photoelastic studies on P and S wave propagation in prestressed media', by Ker C. Thomson, T. J. Ahrens, and M. N. Toksoez [with reply] Geophysics, August 1970, v. 35, p. 716, published online August 1, 1970, doi:10.1190/1.1440126 Dynamic photoelastic studies of p and s wave propagation in prestressed media Geophysics, October 1969, v. 34, p. 696-712, published online October 1, 1969, doi:10.1190/1.1440041
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62273
Deposited By: Tony Diaz
Deposited On:20 Nov 2015 19:27
Last Modified:03 Oct 2019 09:17

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