Stress Recovery Techniques for the Modified Local Green’s Function Method

Resumo

The Modified Local Greens Function Method (MLGFM) is an integral method hybrid of the Finite Element Method (FEM) and the Boundary Element Method (BEM). The method uses the FEM to create discrete projections of the Greens functions that will be used as fundamental solutions in BEM formulation. The MLGFM has the advantage of presenting high convergence for the displacements in the domain, inherited from the FEM, and for the normal stress on the boundary, inherited from the BEM. Despite these advantages, the accuracy of the recovered stresses in the domain has not been studied in previous works. As the MLGFM is a hybrid of the FEM and BEM, techniques used in both methods will be explored in this paper to study the advantages and disadvantages of each one. The techniques that will be used here are the Least Squares procedure, the Zienkiewicz and Zhu (ZZ) recovery, both widely used in FEM, and the integral form derived from the fundamental solution used in the BEM. The techniques will be analyzed in terms of errors and computational cost of each one.