The predictions and applications of fatigue lifetime in alumina and zirconia ceramics

The lifetime prediction of ceramics has been discussed on the basis of the relation between the stress intensity factor KI and the crack velocity V. In this paper, the effects of both cyclic loading and water environment on the KI–V characteristics were studied by the crack growth tests using the double torsion method under static and cyclic loading in both environments of air and water for alumina and zirconia ceramics. The KI–V characteristics determined by the double torsion method were used to predict time-to-failure under cyclic fatigue of alumina and zirconia ceramics. The predictions agreed qualitatively with the experimental results.