High-temperature flexural mechanical properties of SiC/SiC composites

To assess the flexural behavior of SiC/SiC composites in high-temperature atmospheric environments, three critical influencing factors were identified: selection of fixtures, loading and supporting roller dimensions, and span-to-thickness ratio. Subsequently, through experimental methods and finite element model simulations, the impact of these factors was investigated. The study identified the most suitable fixture materials and configuration dimensions for SiC/SiC materials. It was found that as the span-to-thickness ratio increases, the flexural strength of the material continues to rise, reaching a turning point at 543 MPa, after which it decreases. The maximum interlaminar shear stress consistently decreases with an increasing span-to-thickness ratio. Combined with the failure mode analysis of the samples, it was observed that for a span-to-thickness ratio equal to or greater than 16, the sample failure modes are all valid. Additionally, regarding the observed non-linearity in the stress-strain curve when testing with a larger span-to-thickness ratio, it is recommended to apply a large deflection correction to the flexural stress.