A coupled meshless-finite element method for fracture analysis of cracks

This paper presents a coupling technique for integrating the element-free G alerkin method (EFGM) with the traditional finite element method (FEM) for analyzing linear-elastic cracked structures subject to mode-I and mixed-mod e loading conditions. The EFGM was used to model material behavior close to cracks and the FEM in areas away from cracks. In the interface region, the resulting shape function, which comprises both EFGM and FEM shape function s. satisfies the consistency condition thus ensuring convergence of the met hod. The proposed method was applied to calculate mode-I and mode-II stress -intensity factors (SIFs) in a number of two-dimensional cracked structures . The SIFs predicted by this method compare very well with the existing sol utions obtained by all-FEM or all-EFGM analyses. A significant saving of co mputational effort can be achieved due to coupling in the proposed method w hen compared with the existing meshless methods. Furthermore, the coupled E FGM-FEM method was applied to model crack propagation under mixed-mode load ing condition. Since the method is partly meshless, a structured mesh is no t required in the vicinity of the cracks. Only a scattered set of nodal poi nts is required in the domain of interest. A growing crack can be modeled b y simply extending the free surfaces, which correspond to a crack. By sides tepping remeshing requirements, crack-propagation analysis can be dramatica lly simplified. A number of mixed-mode problems were studied to simulate cr ack propagation. The agreement between the predicted crack trajectories wit h those obtained from existing numerical simulation and experiments are exc ellent. (C) 2001 Elsevier Science Ltd. All rights reserved.