Crack growth rate and cracking velocity in fatigue for a class of ceramics

Fatigue crack growth rate data and cracking velocity data are studied for a class of ceramics including SiC, TiB2, Si3N4, ZrO2 and Al2O3. Both sine an d square wave cyclic loading are combined such that the data could be conve rted to cracking velocity for a given frequency of cyclic load. An effectiv e stress intensity factor rang is defined and used in an relation for compu ting the crack growth rate and cracking velocity. As for the metal alloys, the data for ceramics also fall into three regimes identified with near-thr eshold, stable growth and rapid crack extension, except that the slope of t he da/dN (the crack growth rate) curves for ceramics are steeper in compari son with that for metals. Reported are the empirical constants in the relat ions for the crack growth rate and the cracking velocity for a variety of c eramics. (C) 1999 Elsevier Science Ltd. All rights reserved.