Evaluation of Green’s function for vertical point-load excitation applied to the surface of a layered semi-infinite elastic medium

2006 ◽  
Vol 76 (7-8) ◽  
pp. 465-479 ◽  
Author(s):  
Andrej Strukelj ◽  
Tomaz Plibersek ◽  
Andrej Umek
Author(s):  
Mitsuru Nakai ◽  
Leo Sario

If a thin elastic circular plate B: ∣z∣ < 1 is clamped (simply supported, respectively) along its edge ∣z∣ = 1, its deflection at z ∈ B under a point load at ζ ∈ B, measured positively in the direction of the gravitational pull, is the biharmonic Green's function β(z, ζ) of the clamped plate (γ(z, ζ) of the simply supported plate, respectively). We ask: how do β(z, ζ) and γ(z, ζ) compare with the corresponding deflections β0(z, ζ) and γ0(z, ζ) of the punctured circular plate B0: 0 < ∣ z ∣ < 1 that is “clamped” or “simply supported”, respectively, also at the origin? We shall show that γ(z, ζ) is not affected by the puncturing, that is, γ(·, ζ) = γ0(·, ζ), whereas β(·, ζ) is:on B0 × B0. Moreover, while β((·, ζ) is of constant sign, β0(·, ζ) is not. This gives a simple counterexmple to the conjecture of Hadamard [6] that the deflection of a clampled thin elastic plate be always of constant sign:The biharmonic Gree's function of a clampled concentric circular annulus is not of constant sign if the radius of the inner boundary circle is sufficiently small.Earlier counterexamples to Hadamard's conjecture were given by Duffin [2], Garabedian [4], Loewner [7], and Szegö [9]. Interest in the problem was recently revived by the invited address of Duffin [3] before the Annual Meeting of the American Mathematical Society in 1974. The drawback of the counterexample we will present is that, whereas the classical examples are all simply connected, ours is not. In the simplicity of the proof, however, there is no comparison.


1958 ◽  
Vol 36 (2) ◽  
pp. 192-205 ◽  
Author(s):  
J. A. Steketee

In this paper a Green's function method is developed to deal with the problem of a Volterra dislocation in a semi-infinite elastic medium in such a way that the boundary surface of the medium remains free from stresses. (A Volterra dislocation is here defined as a surface across which the displacement components show a discontinuity of the type Δu = U + Ω ×r, where U and Ω are constant vectors.) It is found that the general problem requires the construction of six sets of Green's functions. The method for the construction is outlined and applied to one of the six sets, which is of the type of two double forces with moments in a plane parallel with the boundary. The displacement field thus generated is computed. Several of the results obtained are believed to be of geophysical interest, but a more detailed discussion of these applications is postponed to a further communication which is being prepared.


Geophysics ◽  
2006 ◽  
Vol 71 (4) ◽  
pp. SI79-SI84 ◽  
Author(s):  
K. van Wijk

A controlled ultrasonic laboratory experiment provides a detailed analysis of retrieving a band-limited estimate of the Green's function between receivers in an elastic medium. Instead of producing a formal derivation, this paper appeals to a series of intuitive operations, common to geophysical data processing, to understand the practicality of seismic interferometry. Whereas the retrieval of the full Green's function is based on the crosscorrelation of receivers in the presence of equipartitioned signal, an estimate of the impulse response is recovered successfully with 40 sources in a line covering six wavelengths at the surface.


2010 ◽  
Vol 127 (3) ◽  
pp. 2012-2012 ◽  
Author(s):  
Evgenia A. Zabolotskaya ◽  
Yurii A. Ilinskii ◽  
Mark F. Hamilton

1976 ◽  
Vol 31 (2) ◽  
pp. 183-194
Author(s):  
E. Boschi ◽  
E. Di Curzio

2017 ◽  
Vol 77 ◽  
pp. 123-137 ◽  
Author(s):  
Chao He ◽  
Shunhua Zhou ◽  
Peijun Guo ◽  
Honggui Di ◽  
Junhua Xiao

Author(s):  
Youn-Sha Chan ◽  
L. J. Gray ◽  
T. Kaplan ◽  
Glaucio H. Paulino

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