A Systematic Shear-Lag Approach for Analyzing the Failure Mechanisms in Ceramic Matrix Composites

The present study examines various damage progression criteria to provide input to a shear-lag analysis of ceramic matrix composites (CMCs). The shear-lag as well as other analysis methods require matrix and fiber crack densities in addition to interfacial debond lengths as input to the analysis before the composite behavior can be approximated. The present approach examines criteria for damage progression consisting of a critical matrix strain energy to control matrix crack density, a Weibull-type damage progression scheme for fiber cracks, and ultimate interfacial shear stress to provide debond lengths. Fatigue modeling is also accomplished through an effective fiber pullout where the eventual failure in fatigue is modeled by the available elastic energy exceeding the work to fiber pullout.