A two-scale generalized FEM for the evaluation of stress intensity factors at spot welds subjected to thermomechanical loads

Abstract

This paper presents a two-scale Generalized Finite Element Method with global-local enrichments (GFEMgl) for the evaluation of stress intensity factors (SIFs) at spot welds subjected to thermomechanical loads. The method uses the solution of local boundary value problems as enrichment functions for the global/structural model and can provide accurate solutions on coarse meshes adopted at the structural scale. The faying surface and spot welds are represented by special enrichment functions instead of meshes fitting the weld geometry. This greatly simplifies the model generation process in comparison with a Direct Finite Element Analysis DFEA. Numerical experiments show that the proposed GFEMgl is able to capture the strong gradients and singularities near the spot weld edge. It can provide accurate solutions and SIFs comparable to a 3-D DFEA while requiring significantly less computational resources and user time. The robustness of the method is demonstrated through examples involving spot welds with irregular shapes and built-up panels subjected to sharp thermal fluxes.