This paper presents a novel weak-form block Petrov-Galerkin method (BPGM) for linear elastic and crack problems in functionally graded materials with bounded and unbounded problem domains. The main idea of this approach is to combine the meshless local Petrov-Galerkin method with block method. Once the problem domain is discretized into several sub-regions, named blocks, which can be mapped into normalized square domains. The weak-form Petrov-Galerkin method and polynomial series of interpolations are employed in each block. The computational efficiency is rigorously examined against the strong-form finite block method, the finite element technique and meshless approaches. Numerical results demonstrate that the BPGM possess the following important properties: (1) only a few blocks are required for calculating problems in unbounded regions which saves tedious work of meshing; (2) the displacements and stresses are continuous at the interfaces of neighboring blocks;(3) due to the use of weak formulation, the continuity requirements of the approximation functions are reduced and numerical solutions are stable; (4) because of using Lagrange polynomial interpolation, highly accurate results can be obtained with a small amount of nodes in each block.Emails: liyan001de@gmail.com 2
IntroductionMany engineering problems can be modeled as an extension of either finite or semi-infinite regions. The analytical solutions of these models are often difficult to obtain due to the complexity of material properties and irregular geometries.Numerical techniques are developed to deal with these problems which are modeled by partial differential equations (PDEs), among which the widely used approaches are finite difference method (FDM) [1], finite element method (FEM) [2] and boundary element method (BEM) [3]. The FDM and FEM are mesh dependent and become computationally time demanding on generation of high quality meshes for efficient solutions. The use of fundamental solutions or Green's functions in BEM provides more accurate and efficient approximation. However, it is usually difficult to obtain the fundamental solutions in closed forms, especially for nonhomogeneous and anisotropic materials. In recent decades, meshless techniques were developed to solve practical problems and had drawn the attention of many investigators, including the smooth particle hydrodynamics method [4] , the diffuse element method [5], the element-free Galerkin method (EFG) [6] and the reproducing kernel particle method [7]. Based on the weak Petrov-Galerkin formulation, Atluri and his co-workers developed the meshless local Petrov-Galerkin method (MLPG) with moving least square approximation for problems in arbitrary geometries [8]. Sladek et al. [9] introduced the local boundary integral equation method for boundary value problems in anisotropic non-homogeneous media. Among these meshless approaches, the radial basis functions (RBFs) method [10] was a truly meshless collocation method using in particular the multiquadric shape function [11][12] for...