Durability and Damage Bahavior of 2-D and 3-D SiC/SiC Composites

An overview of the response of 2-D woven and 3-D braided SiC/SiC composites to thermomechanical loading up to a temperature of 1300°C is presented. The composites utilize Nicalon SiC fibers and are manufactured by the chemical vapor infiltration process. Fiber architecture controls the damage behavior of the composites both directly and indirectly by determining the sizes and distributions of microstructural pores within and between fiber bundles. The role of porosity on damage evolution is investigated by studying SiC/SiC composites with two porosity levels. A damage mechanics model based on Ladeveze’s approach is used to analyze the damage behavior of the composites. In addition to failure under tension, compression and bending, the fracture behavior of 2-D SiC/SiC composites is characterized through the application of various energy approaches based on the linear elastic fracture mechanics and J-integral methods. The toughness parameters thus obtained are compared and the suitability of the approaches discussed.