A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Civil Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 2000

XFEAP is a general purpose FEM code which offers a wide variety of element types and applications for solving problems in the area of solid mechanics. All of these element subroutines are well tested and developed over the past 20 years. Although XFEAP has great benefit, it is too difficult to generate mesh or remesh certain types of problems including complex 3D objects, large deformation problems and domain discontinuities like cracks. In order to avoid these problems, the element-free Galerkin method (EFGM) is added so users can choose which methods (FEM, EFGM or both) are suitable for their specific problems. This work adapts some current element subroutines including 2D-3D linear and nonlinear formulations to enable EFGM analyses via the technique of coupling FEM and EFGM. Consequently, the difficulties of enforcement of boundary condition in EFGM are solved by using finite elements along essential boundaries of the problem domain. Original macro commands, tools for preparing data for calculation in XFEAP, are employed to construct the discrete model for the subsequent analyses, but some changes are required to ensure the compatibility of both methods. The profile solver in XFEAP, which is fast and efficient, is utilized for solving the global system of discrete equations. The modified XFEAP program offers the ability for users to write their own element subroutines for solving particular problems with both FEM and EFGM analysis techniques. Numerical examples in 2D and 3D elasticity and elastoplasticity show that the implementation is capable of computing accurate stress and displacement fields for a wide variety of problems.