Comparison of the Conventional and Extended Finite Element Methods in Fracture Prediction of Keyhole Notch Specimen under Mixed Mode Loading

Due to the noticeable stiffness and also very low deformability, brittle materials have vast application in the various industries such as automobile, navy, and aero. Therefore, investigation of failure behaviour and mechanical fracture of these materials is one of the most important challenges of the engineers and researchers. The main aim of this paper is to compare the performance of the extended finite element method (XFEM) with the conventional finite element method (CFEM) in prediction of crack initiation and propagation in a brittle material. For this purpose first, applying the damage models based on the CFEM and XFEM available in ABAQUS finite element software, crack onset and growth in a graphite specimen with keyhole notch is simulated. Then, values of crack initiation angle and maximum load capacity in the sample under different mixed mode loading conditions are predicted, compared with experimental results and validated. Comparison of the numerical results obtained from the CFEM and XFEM simulations with the empirical results reveals that the XFEM in addition to decreasing the computational costs and also reducing sensitivity to the element size in the mesh has higher accuracy and more performance in prediction of crack initiation and propagation in the brittle materials, compared with the CFEM.