Green’s Functions for Infinite and Semi-infinite Anisotropic Thin Plates

2003 ◽  
Vol 70 (2) ◽  
pp. 260-267 ◽  
Author(s):  
Z.-Q. Cheng ◽  
J. N. Reddy

This paper presents fundamental solutions of an anisotropic elastic thin plate within the context of the Kirchhoff theory. The plate material is inhomogeneous in the thickness direction. Two systems of problems with non-self-equilibrated loads are solved. The first is concerned with in-plane concentrated forces and moments and in-plane discontinuous displacements and slopes, and the second with transverse concentrated forces. Exact closed-form Green’s functions for infinite and semi-infinite plates are obtained using the recently established octet formalism by the authors for coupled stretching and bending deformations of a plate. The Green functions for an infinite plate and the surface Green functions for a semi-infinite plate are presented in a real form. The hoop stress resultants are also presented in a real form for a semi-infinite plate.

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).


2003 ◽  
Vol 70 (2) ◽  
pp. 180-190 ◽  
Author(s):  
E. Pan

In this paper, three-dimensional Green’s functions in anisotropic elastic bimaterials with imperfect interface conditions are derived based on the extended Stroh formalism and the Mindlin’s superposition method. Four different interface models are considered: perfect-bond, smooth-bond, dislocation-like, and force-like. While the first one is for a perfect interface, other three models are for imperfect ones. By introducing certain modified eigenmatrices, it is shown that the bimaterial Green’s functions for the three imperfect interface conditions have mathematically similar concise expressions as those for the perfect-bond interface. That is, the physical-domain bimaterial Green’s functions can be obtained as a sum of a homogeneous full-space Green’s function in an explicit form and a complementary part in terms of simple line-integrals over [0,π] suitable for standard numerical integration. Furthermore, the corresponding two-dimensional bimaterial Green’s functions have been also derived analytically for the three imperfect interface conditions. Based on the bimaterial Green’s functions, the effects of different interface conditions on the displacement and stress fields are discussed. It is shown that only the complementary part of the solution contributes to the difference of the displacement and stress fields due to different interface conditions. Numerical examples are given for the Green’s functions in the bimaterials made of two anisotropic half-spaces. It is observed that different interface conditions can produce substantially different results for some Green’s stress components in the vicinity of the interface, which should be of great interest to the design of interface. Finally, we remark that these bimaterial Green’s functions can be implemented into the boundary integral formulation for the analysis of layered structures where imperfect bond may exist.


2015 ◽  
Vol 20 (2) ◽  
pp. 345-372
Author(s):  
B. Rogowski

Abstract The subject of the paper are Green’s functions for the stress intensity factors of modes I, II and III. Green’s functions are defined as a solution to the problem of an elastic, transversely isotropic solid with a penny-shaped or an external crack under general axisymmetric loadings acting along a circumference on the plane parallel to the crack plane. Exact solutions are presented in a closed form for the stress intensity factors under each type of axisymmetric ring forces as fundamental solutions. Numerical examples are employed and conclusions which can be utilized in engineering practice are formulated.


A procedure is described to generate fundamental solutions or Green’s functions for time harmonic point forces and sources. The linearity of the field equations permits the Green’s function to be represented as an integral over the surface of a unit sphere, where the integrand is the solution of a one-dimensional impulse response problem. The method is demonstrated for the theories of piezoelectricity, thermoelasticity, and poroelasticity. Time domain analogues are discussed and compared with known expressions for anisotropic elasticity.


1998 ◽  
Vol 103 (2) ◽  
pp. 888-899 ◽  
Author(s):  
R. Gunda ◽  
S. M. Vijayakar ◽  
R. Singh ◽  
J. E. Farstad

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