Calibration and Verification of XFEM Model to Predict Ductile Fracture

The XFEM (Extended Finite Element Method) has emerged as a reliable tool for structural engineers to study fracture problems. This method was introduced in 1999 as an alternative to the solution of models with inclusions and discontinuities. As it is a recent method and despite being available in most of the commercial software, the modeling with XFEM lacks assessment on the sensitivity of the method in terms of mesh refinement and other parameters that need to be suitable for building the model. This experimental and numerical study explores the Extended Finite Element Method to predict ductile crack propagation of typical fracture specimens made of a pressure vessel ASTM A285 steel. First, a detailed parametric study is conducted to reproduce the load versus displacement curve obtained from a fracture toughness test using deep crack bend samples. Then, after calibrating the model parameters, the model is used to predict the response of specimens with different levels of crack-tip triaxiality. For this purpose, shallow crack bend specimens with and without side grooves are modeled and compared to experimental toughness tests. Overall, a good agreement between experimental and numerical responses was observed.