Author(s)

J. T. Chen, W. S. Huang, Y. T. Lee, S. K. Kao

Abstract

In the development of finite element method (FEM), the patch test is required. We may wonder whether we need any special test for the boundary element method (BEM). A sufficient and necessary boundary integral equation method (BIEM) to ensure a unique solution is our concern. In this paper, we revisit this issue for the interior two-dimensional (2-D) elasticity problem and investigate the equivalence of solution space between the integral equation and the partial differential equation. Based on the degenerate kernel and the eigenfunction expansion, the range deficiency of the integral operator of the single-layer potential for the solution space in the degenerate-scale problem for the 2-D elasticity in the BIEM is analytically studied. Following the Fichera’s idea, we enrich the conventional BIEM by adding constants and corresponding constraints. In addition, we introduce the concept of modal participation factor (MPF) to examine whether the adding term of the rotation is required for interior simply-connected problems. Finally, a simple example of the degenerate-scale problem containing an elliptical boundary subjected to various boundary conditions of the rigid body translation and rotation for 2-D elasticity problems was demonstrated by using the necessary and sufficient BIEM.

Keywords

boundary integral equation, boundary element method, Fichera’s method, degenerate scale, degenerate kernel