MODELING OF FATIGUE IN CROSS-PLY CERAMIC-MATRIX COMPOSITES

This study proposes a methodology for modeling the fatigue response of cross-ply ceramic matrix composites (CMCs). The micromechanics based analysis and failure criteria are formulated to model stress-strain hy steresis, strain ratchetting and S-N behavior specific to room-tempera ture cyclic loading environments. The damage mechanisms considered are matrix cracking in the 90 degrees and 0 degrees plies, fiber/matrix i nterfacial debonding, fiber fracture, and fiber pull-out. These damage modes are modeled by a set of failure criteria with a minimum relianc e on empirical data which can be easily employed in a variety of numer ical and analytical techniques. The predicted results are found to be in good agreement with the experimental data; however, it is observed that the assumed degradation in the frictional resistance along the fi ber/matrix interface plays a dominant role in determining the fatigue response.