Characteristics of interfaces in 3D fine weave carbon/carbon composites

Statistical analysis of in-situ fiber bundle failure was carried out for 3D C/C composites processed by different technologies. An in-situ interfacial strength testing instrument was used to determine the fiber/matrix bond properties of C/C composites. A micromechanical model for the study of stress and strain fields along fiber/matrix interfaces was introduced and a method for description of the interface properties through debonding force and mechanical properties of fibers, matrices and composites was provided. The analytic results provide an optimal design for C/C composites. High temperature processing decreases the fiber bundle strength up to about 20%. A comparison of different interfaces reveals that fiber bundles in the z-direction have the strongest bounding and the best interface structure.