Compliance analysis of a bridged crack under monotonic and cyclic loading

A systematic approach for crack bridging in quasibrittle materials, such as coarse-grained alumina ceramics, is extended to study frictional degradation in grain bridges during cyclic fatigue. It is shown that the variation in bridging stress owing to the grainbridge degradation can be determined in terms of compliance measurements. Parallel to the bridging theory under monotonic loading, the extended analysis under cyclic loading is divided into two parts: i.e. the pure frictional degradation of existing bridges without any crack growth, and the coupling problem of the establishment of new bridges accompanying fatigue crack growth and degradation of old bridges subject to cyclic fatigue. Preliminary results on bridging stresses in a coarse-grained alumina under monotonic loading are obtained with the bridging theory.