Non-intrusive coupling of a 3-D Generalized Finite Element Method and Abaqus for the multiscale analysis of localized defects and structural features

This paper presents a multiscale computational framework able to resolve localized defects and features such as cracks and welds in large structures. It couples Abaqus models and 3-D Generalized Finite Element (GFEM) discretizations enriched with numerically-defined functions – the GFEM with global-local enrichments (GFEM^gl). The structural-scale problem is modeled in Abaqus using a coarse, 3-D mesh, suitable for capturing the global response of the structure. The GFEM^gl is used to accurately model localized features of interest that are otherwise ignored by Abaqus models. The GFEM^gl utilizes enrichment functions provided by the solution of, potentially multiple, local problems solved in parallel. The coupling between Abaqus and GFEM^gl models is handled by the Iterative Global-Local method (IGL). The proposed multiscale framework – denoted by the acronym IGL-GFEM^gl in this work – is non-intrusive in the sense that the interactions between Abaqus and the GFEM^gl solver require no modifications of Abaqus or knowledge about its implementation of the FEM. Numerical examples of a specimen undergoing localized plasticity, a hat-stiffened panel with a large number of spot welds, and a T-joint structure subjected to mixed-mode fatigue crack propagation are presented to demonstrate the accuracy and applicability of the proposed framework. The results show that the IGL-GFEM^gl can achieve nearly the same accuracy as a Direct Finite Element Analysis (DFEA) while leveraging methodologies and algorithms implemented in commercial and research software. Moreover, it is also shown that the user time spent on model preparation can be greatly reduced when dealing with complex problems.