13th International Conference on Fracture June 16–21, 2013, Beijing, China -4- (see Romero de la Osa et al. [3]). The identification of the parameters reported in Table 2, the predicted curve V-KI being in agreement with the experimental data (see Fig. 3). Figure 2. (a) Schematic description to model the zirconia SCG subjected to mode I, plain strain loading, (b) General view and zoom around the crack tip of the mesh used for the finite element analysis. Figure 3. Calibration of cohesive zone parameters for zirconia based on experimental data [7] of SCG of zirconia single crystals Table 1. Cubic elastic constants of zirconia single crystals (data from [9]) C11 (GPa) C22 (GPa) C33(GPa) 430 94 64 Table 2. Parameters for the cohesive zone model for SCG in a zirconia single crystal U0 (kJ/mol) n cr (nm nm3) 0 (mm/s) 160 1 0.027 3.2 1011 3. Simulation and prediction of SCG in 2D zirconia polycrystal We use the cohesive parameters indentified in the foregoing section to describe intergranular fracture under SCG in a polycrystal. We consider a granular zone composed by anisotropic hexagonal grains with random direction and with cohesive surfaces inserted along the grain boundaries. The problem formulation is depicted in Fig. 4. The polycrystalline zone is embedded in a continuum, homogeneous equivalent medium. An initial crack emerges in the granular zone. Along the remote boundary, the mode I K-fields are prescribed. Intergranular failure is allowed. The cubic elastic constants of zirconia grains are reported in Table 1 and the coefficients of thermal expansion are (1 = 3 = 10 × 10 -6 K-1, 2 = 11 × 10 -6 K-1). The surrounding homogenous linear
RkJQdWJsaXNoZXIy MjM0NDE=