Interlaminar Tension/Shear Properties and Stress Rupture in Shear of Various Continuous Fiber‐Reinforced Ceramic Matrix Composites

Interlaminar tensile and shear strengths of six different fiber-reinforced ceramic matrix composites were determined at ambient temperature with transthickness tension and double-notch shear test methods, respectively. Overall, interlaminar shear strength was about three times greater than interlaminar tensile strength for the composites considered. Some size effect on interlaminar shear strength was observed for SiC/SiC composites. Rate dependency of shear strength of a Hi-Nic SiC/SiC composite was also determined at 1316 °C in air using constant shear stress-rate testing. Degradation of interlaminar shear strength with decreasing shear stress rate, termed rate dependency or delayed failure, was observed. A previously proposed phenomenological model was used to account for and to quantify the rate dependency of interlaminar shear strength of the composite. Additional stress rupture testing in shear for the same SiC/SiC composite was conducted at 1316 °C in air to validate the proposed model. Notwithstanding the limited number of test specimens used, the model was in reasonable agreement with the stress rupture data.