Simulation of crack propagation behavior of nuclear graphite by using XFEM, VCCT and CZM methods

In order to study the fracture performance of nuclear graphite, numerical simulations were performed on single-edge notched graphite beam subjected to three-point bending by using XFEM, CZM and VCCT in ABAQUS. The dependence of peak load Pc on the element size was analyzed and numerical results indicated that the Pc is sensitive to the mesh size using the three methods and it is the most sensitive using VCCT. For the three models, the influences of critical parameters such as maximum principal stress σmax for the XFEM, τc nominal interfacial strength for the CZM and critical strain energy release rate GIc and GIIc for the VCCT, on the load-displacement curves were evaluated. Furthermore, by comparing with the experimental results measured by ESPI technique, the reliability of the finite element model was validated and appropriate values of the parameters for fracture simulation of IG11 graphite by using the three models were proposed. The influences of mesh size and above fracture parameters on the critical crack length ac were analyzed. Finally, through the strain field at the crack tip, the lengths of the crack in graphite were determined.