| In this research, a single-notch bar of single crystal superalloy PWA 1480 was studied with the finite element method (FEM). Stress and strain concentrations at the notch under different levels of tensile loading were investigated, considering two typical notch orientations in terms of material [110] and [100] directions, based on anisotropic material properties. Orientation dependence of the notch effect on the stress and strain concentrations was discussed. The FEM model of the single notch bar was further complicated with embedding a semi-elliptical crack at the notch root. The pointwise J integral along the semi-elliptical crack front and the crack opening displacement (COD) behind two typical crack front positions, which are in the short and long semi-axes respectively, were evaluated respectively for the two notch orientations at different tensile load levels. Three crack sizes were considered in the model in order to investigate the crack size effect on the crack tip characteristic parameters, such as J integral, COD and crack tip opening displacement (CTOD). The anisotropic effect on the J integral was also compared with that of isotropic materials. A correlation was established between the J integrals of a semi-elliptical crack front point and a through-the-thickness crack evaluated based on the continuously distributed dislocation theory (CDDT). Finally, the correlation factor n between the J integral and CTOD was evaluated, similarly to isotropic material, based on the elastic-plastic fracture mechanics (EPFM). |
