Damage Mechanics of Two-Dimensional Woven SiC/SiC Composites

The paper reports an analysis and modeling of the damage behavior of two-dimensional woven SiC/SiC composites. The damage mechanics analysis originally developed by Ladeveze and coworkers for polymeric and C/C composites are adopted and extended for ceramic matrix composites. The experimental findings of the coauthors reported in a companion paper provides the data for analytical modeling. The damage model assumes quasi-isotropic elastic behavior of the undamaged SiC/ SiC composites as well as orthotropic damage development (e.g., matrix microcracking, interfacial debonding, and fiber fracture). The model utilize two damage variables which are determined from experimental data; and the constitutive relation takes into account the difference in damage development between tension and compression in the principal material directions. The validity of the theory is demonstrated by the prediction of damage evolution of a SiC/SiC specimen under four-point bend test based upon the experimental data of tension and compression tests. A finite element method coupled with damage is adopted for the flexural analysis. The predictions agree quite well with experimental results.