Numerical Study of SIF for a Crack in P265GH Steel by XFEM

Abstract

The analytical solving of fracture mechanics equations remains insufficient for complex mechanisms, hence the use of finite element numerical methods (FEM). But the presence of singularities strongly degrades the FEM convergence and refining the mesh near the singularities is not enough to obtain an accurate solution, hence the use of the extended finite element method (XFEM). With XFEM, the standard finite element approximation is locally enriched by enrichment functions to model the crack. The present work focuses on the numerical study of the defects harmfulness in the P265GH steel of a Compact Tension (CT) specimen. A stress intensity factor (SIF) was calculated by CAST3M code, using XFEM and the G-Theta method in the FEM; the objective is to simulate a CT sample with XFEM in 3D and to calculate the critical length of crack leading to the fracture as well as the evolution of stress concentration coefficient. An integration strategy and a definition of level sets have been proposed for cracks simulation in XFEM. A weak loading was considered to ensure elastic behavior. A comparative study of the numerical SIF values with the theory was performed. The result shows that XFEM is a precise tool for modeling crack propagation.