MODEL OF THE NONLINEAR MECHANICAL-BEHAVIOR OF 2D SIC-SIC CHEMICAL-VAPOR INFILTRATION COMPOSITES

An approach to the nonlinear stress-strain behavior of ceramic matrix composites was proposed, based upon damage mechanics. Damage-loading r elations taking into account effects of anisotropy and coupling were e stablished. These relations allowed prediction of the stress-strain be havior, and ultimate failure. The theory was then applied to a 2D SiC/ SiC composite subject to tensile loading under 0-degrees, 20-degrees, and 45-degrees off-axis angles. A two-stage damage mechanism was ident ified by optical microscopy on specimens under load. Predictions of th e stress-strain behavior were in excellent agreement with experimental data.