Cyclic Fatigue Crack Propagation in Alumina under Direct Tension—Compression Loading

Cyclically induced crack propagation occurs in alumina subjected to direct tension—compression loading. The crack increment per cycle (da/dN) has a power‐law dependence on the peak stress intensity factor (K max ). Cyclic crack growth can occur at lower values of K max than are required to produce static fatigue effects. Subcritical crack‐growth behavior was found to be dependent on specimen geometry: it is suggested that direct compressive loads and crack length are both factors that affect cyclic fatigue behavior, and that the use of K alone to characterize fatigue crack growth in ceramics may be questionable.