Fatigue and Static Fracture of Machineable C/C Composites

The fatigue and fracture behavior of C/C composites fabricated using fine-woven carbon fiber laminates were investigated in several notched and smooth specimens. Slits and notches were cut in some specimens, and the effect of fiber direction and notch configuration on the fatigue behavior was examined. Axial load or bending moment was applied, and the fracture strength and the fracture mechanism were investigated. The fatigue limit was dependent on stress ratio, fiber direction and notch configuration. It was found that the fatigue limit and tensile strength of the notched specimens were higher than those of the smooth specimens. So, the fracture behavior of the material was different from metals and plastics. The local interlaminar debonding of fiber sheets and local shear deformations are important factors in the evaluation of static and fatigue strength.