Fracture Toughness Testing and Prediction for Ceramic Materials Using in Large-Flow-Rate Emulsion Pumps

Fracture toughness (K IC ) tests have been carried out on single edge precracked beam specimens with dimensions in accordance with ISO15732 requirements for two types of zirconia and one type of alumina, i.e. ZrO 2 -1, ZrO 2 -2 and Al 2 O 3 . Experimental determinations of K IC for the two zirconia and one alumina materials are 12.18 MPa•m 1/2 , 16.35 MPa•m 1/2 and 4.99 MPa•m 1/2 , respectively. The median rank method is used to calculate the probability of fracture, F(K IC ) of the three cermaic materials for representing the experimental results. The SEM analysis on fracture surfaces of ZrO2-1 materials is carried out, which indicates the fracture in ZrO 2 -1 material occurred at the interior of the grain associated with interior stress distribution with principal components of ZrO 2 and SiO 2 . Th extended finite element method (XFEM), based on the linear elastic fracture mechanics in conjuciton with a bilinear traction-separation damage law, is used to simulate the progressive crack growth process in the SEPB specimens. The XFEM predicted K IC results are compared with the corresponding experimental data. The XFEM approach overpredicts the K IC values, from 10.4% to 25.6%, for the three ceramic materials. The possible reasons, in the aspect of loading conditions and contact assumptions, for the difference between the predicted and tested results are also discussed.