Interface degradation in ceramics under cyclic loading

The role of the interfaces in the fracture event is studied in monolithic ceramic microstructures. As an alternative approach to R-curves, the toughening of alumina is described via the post-fracture tensile (PFT) test, which has previously been introduced as a method for the direct evaluation of the wake zone traction function. This universal description of the toughening behavior has previously been related to the elements of the microstructure, including thermoelastic constants, grain size and distribution, and grain boundary character. This presentation will address the behavior of the wake process zone microstructure subjected to cyclic loading environments. Where the classical R-curve behavior relates largely to the scale of the grains, the cyclic degradation problem seems to respond to microstructural features of a scale about 1 to 2 orders of magnitude smaller, focusing attention toward the interfacial character.