On the residue calculus evaluation of the 3-D anisotropic elastic green's function

2004 ◽  
Vol 20 (5) ◽  
pp. 335-341 ◽  
Author(s):  
A.-V. Phan ◽  
L. J. Gray ◽  
T. Kaplan
2008 ◽  
Vol 75 (5) ◽  
Author(s):  
T. C. T. Ting

The Green’s function for an anisotropic elastic half-space that is bonded to a thin elastic material of different anisotropy subject to a line force and a line dislocation is presented. Also presented is the Green’s function for two different anisotropic elastic half-spaces that are bonded to a thin elastic material of different anisotropy subject to a line force and a line dislocation in one of the half-spaces. The thickness h of the thin layer is assumed to be small compared with a reference length. Thus, instead of finding the solution in the thin layer and imposing the continuity conditions at the interface(s), we derive and apply effective boundary conditions for the interface between the layer and the body that take into account the existence of the layer.


2004 ◽  
Vol 71 (5) ◽  
pp. 672-676
Author(s):  
B. Yang

Defect Green’s function (GF) of multiple point-like inhomogeneities in a multilayered solid has been derived within the theory of linear anisotropic elasticity. It is related to the (reference) GF of the multilayered matrix excluding the inhomogeneities through the continuum Dyson’s equation. While the reference GF is available, the defect GF can be solved. The expressions are first analytically reduced by realizing the point-likeness of the inhomogeneities. The subsequent procedure involves the solution of the response of each individual inhomogeneity to a far-field straining in the multilayered matrix and a matrix inversion on the order of the number of inhomogeneities. Furthermore, the defect GF is applied to derive the field induced by inhomogeneous substitutions in a multilayered solid. Numerical results are reported for arrays of cubic and semispherical Ge inclusions in a Si/Ge superlattice. The numerical results have demonstrated the validity and efficiency of the present formulation.


Author(s):  
Václav Vavryčuk

An asymptotic Green's function in homogeneous anisotropic viscoelastic media is derived. The Green's function in viscoelastic media is formally similar to that in elastic media, but its computation is more involved. The stationary slowness vector is, in general, complex valued and inhomogeneous. Its computation involves finding two independent real-valued unit vectors which specify the directions of its real and imaginary parts and can be done either by iterations or by solving a system of coupled polynomial equations. When the stationary slowness direction is found, all quantities standing in the Green's function such as the slowness vector, polarization vector, phase and energy velocities and principal curvatures of the slowness surface can readily be calculated. The formulae for the exact and asymptotic Green's functions are numerically checked against closed-form solutions for isotropic and simple anisotropic, elastic and viscoelastic models. The calculations confirm that the formulae and developed numerical codes are correct. The computation of the P -wave Green's function in two realistic materials with a rather strong anisotropy and absorption indicates that the asymptotic Green's function is accurate at distances greater than several wavelengths from the source. The error in the modulus reaches at most 4% at distances greater than 15 wavelengths from the source.


Author(s):  
T. T. C. Ting

One of the basic solutions for anisotropic elasticity, and for other subject for that matter, is the Green's function. The importance of Green's functions in constructing solutions to boundary value problems has been well recognized. We will study in this chapter Green's functions for infinite spaces, half-spaces, and bimaterials that consist of two half-spaces of dissimilar materials bonded together. Also studied are a composite space that consists of wedges of dissimilar materials and an angularly inhomogeneous space. Green's functions for the infinite space with the presence of a crack, an elliptic hole, or an elliptic inclusion will be studied in separate chapters. We will be concerned mainly with Green's functions due to a line of concentrated forces and a line dislocation that have the r-1 stress singularity where r is the radial distance from the line of forces or the line dislocation. Green's functions due to a concentrated couple, a double force, a center of dilatation, etc., that provide the r-2 stress singularities will be discussed in Section 8.12. We will see that most solutions can be expressed in a real form with the identities presented in Chapters 6 and 7. The Green's function for two-dimensional deformations of an infinite anisotropic elastic material subject to a line dislocation has been obtained by Eshelby et al. (1953), Stroh (1958), Willis (1970), Malen and Lothe (1970), and Malen (1971). Further developments of the Green's function to include a line force was given by Barnett and Lothe (1975a). The solution was in a complex form. A real form solution using an integral representation was derived by Barnett and Swanger (1971) and Asaro et al. (1973) (see also Mura, 1975). Most of the real form solutions obtained by these authors were for the displacement gradient, and hence for the strain. The stress was then obtained indirectly through the stress-strain relations. Chadwick and Smith (1977) did present real form solutions for the displacement as well as the stress directly. The solutions required the inverse of the 6x6 matrix (x1I + x2N) which can be achieved by employing (7.9-17).


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