STEADY-STATE CRACKING IN CERAMIC MATRIX COMPOSITES

The problem of steady-state cracking in which the crack extends under a constant load is investigated for two interface conditions: elastic (no slip) and frictional interface. The fiber, matrix and interface stresses in the cracked and uncracked regions of a unidirectional composite subjected to remote axial stress are obtained using an improved shear-lag theory that accounts for the axial and transverse load-carrying capacity of the matrix. The fiber axial stresses in the current problem coincide with those of previous models. However, the matrix shear and transverse normal stresses predicted in the present model for the interface conditions considered are different. The critical cracking conditions are established by using a generalized energy release rate formulation, and critical stresses are obtained in terms of microstructural properties of the constituents and the interface. © 1990.