The numerical Green's function technique for an infinite isotropic domain with multiple cracks is developed. The singularities considered are the line force and dislocation. The Green's function is decomposed into the singular and the image terms. To obtain the image term we represent the crack opening displacement (COD) by the dislocation dipole distribution, embed the √ r crack tip behavior, and integrate the resulting singular/hyper-singular integrals analytically. The resulting whole crack singular element (WCSE) consists of multiple independent crack opening modes and is strictly algebraic with the correct crack tip singular behavior but the magnitude for each mode is unknown. They are determined to give the negative of the crack surface traction induced by the singular term. Extensive error analysis is performed for the line force and dislocation in an infinite domain with a single crack to identify the region where, when these singularities are placed, the solution achieves high accuracy. Following the guideline set by the error analysis, numerical Green's functions for a few multiple crack configurations are obtained for the line force and dislocation.
IntroductionThe fundamental solutions, such as for the line force and dislocation, are defined in an infinite homogeneous body and their main characteristic is the singularity. When defects (such as cracks and holes) and inhomogeneities (such as inclusions) are introduced the fundamental solutions do not satisfy their required boundary conditions for the defects any more and additional terms are needed if these boundary conditions are enforced. The fundamental solution augmented by the additional image term that satisfy the required boundary conditions is called the Green's function. The fundamental solutions considered in this paper are for the line force and dislocation. These fundamental solutions serve as the essential building block for the solutions of the linear elastic problems by the boundary element method (BEM). Given these fundamental solutions, we establish a technique to determine their Green's functions numerically when multiple cracks are present in two-dimensional isotropic solids. Such Green's functions are called the numerical Green's functions by Telles et al. [1,2,3] The majority of the Green's functions are analytical and are concerned about the simplest defect/inhomogeneity geometries possible such as the single center crack (Snider and Cruse [4], Cruse [5], Clements and Haselgrove [6]) or interface crack (Berger and Tewary [7], Yuuki and Cho [8]), the single elliptical hole (Morjaria and Mukherjee [9], Ang and Clements [10], Kamel and Liaw [11], Hwu and M. Denda and P. Quick / Electronic Journal of Boundary Elements, Vol. 2, No. 1, pp. 22-68 (2004) 22 Yen [12], Denda and Kosaka [13]), and the half-plane/bimaterial domain (Telles and Brebbia [14], Meek and Dai [15], Dumir and Mehta [16], Pan et al. [17], Berger [18], Denda [19]). The only simple geometric configurations have allowed the analytical derivation of these Gree...