Subcritical Crack Growth in Brittle Materials: Mechanics
Sheldon M. Wiederhorn
The fracture of ceramic materials is often preceded by subcritical crack growth originating from flaws or cracks contained in these materials. Subcritical crack growth usually results from a stress-enhanced chemical interaction between the solid and moisture in the environment and has been observed in glasses, porcelains, oxides, silicate minerals and titanates. Since subcritical crack growth precedes catastrophic fracture, a delay to failure is often observed in components subjected to a static load. Subcritical crack growth also leads to a time dependence of the strength, the slower the loading rate, the weaker the material. The science of fracture mechanics provides a logical framework for understanding the effect of subcritical crack growth on structural ceramics and for predicting lifetime.