Extensions of the two-scale generalized finite element method to nonlinear fracture problems

This paper presents an extension of a two-scale generalized finite element method (GFEM) to three-dimensional fracture problems involving confined plasticity. This two-scale procedure, also known as the generalized finite element method with global-local enrichments (GFEM^gl), involves the solution of a fine-scale boundary value problem defined around a region undergoing plastic deformations and the enrichment of the coarse-scale solution space with the resulting nonlinear fine-scale solution through the partition-of-unity framework. The approach provides accurate nonlinear solutions with reduced computational costs compared to standard finite element methods, since the nonlinear iterations are performed on much smaller problems. The efficacy of the method is demonstrated with the help of numerical examples, which are three-dimensional fracture problems with nonlinear material properties and considering small-strain, rate-independent J² plasticity.