Weakest-link failure prediction for ceramics IV : application of mixed-mode fracture criteria for multiaxial loading

Strength data obtained from uniaxial and biaxial bend tests on 2 alumina ceramics were analyzed by a weakest-link model with different mixed-mode fracture criteria and crack shapes. Taking the data from 3- and 4-point bend tests as a ref., strength predictions for the ball-on-ring and ring-on-ring biaxial tests were made, showing large differences in the predictions for the different fracture criteria. The best fitting models for the 2 aluminas cannot be interchanged, thus showing a marked difference in their shear stress sensitivity. Anal. shows that, in general, a combination of tests with a varying degree of stress multiaxiality is required to det. the best applicable mixed-mode fracture criterion. [on SciFinder (R)]