On Green’s function for a three-dimensional exponentially graded elastic solid

The problem of a point force acting in an unbounded, three-dimensional, isotropic elastic solid is considered. Kelvin solved this problem for homogeneous materials. Here, the material is inhomogeneous; it is ‘functionally graded’. Specifically, the solid is ‘exponentially graded’, which means that the Lamé moduli vary exponentially in a given fixed direction. The solution for the Green’s function is obtained by Fourier transforms, and consists of a singular part, given by the Kelvin solution, plus a nonsingular remainder. This grading term is not obtained in simple closed form, but as the sum of single integrals over finite intervals of modified Bessel functions, and double integrals over finite regions of elementary functions. Knowledge of this new fundamental solution for graded materials permits the development of boundaryintegral methods for these technologically important inhomogeneous solids.