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Studies in Acoustic Pulse Propagation


Spencer, Terry Warren (1956) Studies in Acoustic Pulse Propagation. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/RAV7-NV35.


A theoretical study is made of the transient response in two acoustic systems. Each system consists of an ideal fluid in contact with an elastic solid. In one case the interface is plane, in the other case it is cylindrical. In the plane case it is found that an exact algebraic solution can be obtained on the axis of symmetry. The vertical displacement at axial points is composed of the acoustic, afterflow, and correction terms. In solids for which Poisson's ratio is greater than one third the initial variation of the correction is toward positive values (corresponding to motion directed toward the interface). In solids for which Poisson's ratio is less than one third the initial variation may be either positive or negative depending on the magnitude of the compressional velocity ratio. An interface wave is shown to exist regardless of the choice of elastic parameters. It is found that the reflected wave has a forerunner in the region of the fluid in which the refracted wave is the first arrival. In the cylindrical case the initial pulse shape is distorted upon reflection. It is found that as the wave approaches the axis of the cylinder the leading edge steepens. If, at the source, the initial slope of the pressure-time curve is finite the amount of steepening is infinite. An exact expresson for the transient response at points off the axis is obtained which can be evaluated by numerical means.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Geophysics and Physics)
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Geophysics
Minor Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Dix, Charles Hewitt
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1956
Record Number:CaltechETD:etd-06292004-161005
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2771
Deposited By: Imported from ETD-db
Deposited On:30 Jun 2004
Last Modified:09 Aug 2023 18:02

Thesis Files

PDF (Spencer_tw_1956.pdf) - Final Version
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