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 P_c on the element size was analyzed and numerical results indicated that the P_c 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 σ_max for the XFEM, τ^c nominal interfacial strength for the CZM and critical strain energy release rate G_Ic and G_IIc 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 a_c were analyzed. Finally, through the strain field at the crack tip, the lengths of the crack in graphite were determined.

为了研究核石墨的断裂性能，在ABAQUS中利用XFEM、CZM和VCCT对单边缺口石墨梁进行了三点弯曲的数值模拟。峰值负载的依赖性P _Ç上的元件尺寸进行分析并数值计算结果表明，P _Ç是使用三种方法网格尺寸敏感，它是使用VCCT最为敏感。对于这三种模型，XFEM 的最大主应力σ _max、CZM 的标称界面强度τ ^c和临界应变能释放率G _{I c}和G等关键参数的影响_{II c}对于 VCCT，对载荷-位移曲线进行了评估。此外，通过与ESPI技术测量的实验结果进行比较，验证了有限元模型的可靠性，并提出了使用三种模型进行IG11石墨断裂模拟的合适参数值。分析了网格尺寸及以上断裂参数对临界裂纹长度a _{c 的}影响。最后，通过裂纹尖端的应变场，确定石墨中裂纹的长度。