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

Abstract

Fracture toughness (KIC) 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. ZrO2 -1, ZrO2 -2 and Al2O3. Experimental determinations of KIC for the two zirconia and one alumina materials are 12.18 MPa•m1/2, 16.35 MPa•m1/2 and 4.99 MPa•m1/2, respectively. The median rank method is used to calculate the probability of fracture, F(KIC) 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 ZrO2 -1 material occurred at the interior of the grain associated with interior stress distribution with principal components of ZrO2 and SiO2. 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 KIC results are compared with the corresponding experimental data. The XFEM approach overpredicts the KIC 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.