Notch Sensitivity on Fatigue Behavior of Carbon-Carbon Composites

摘要

The fatigue strengths in notched specimens of carbon-carbon composites were investigated. Slits of different length were cut on both sides of a test section to investigate the impact of notch sensitivity on fatigue life. Specimens with blunt-notches on the both side of the specimen, and center hole were also used to compare the critical stress, σw. The fatigue limit was measured using S-N curves. From the experimental result, it was found that specimens with blunt-notches have lowest fatigue limit. The relationships between critical stress, σw and specimen geometry were investigated by stress concentration factor, Kt and stress intensity factor, KI which was done two dimensional body forced methods. Consequently, it was discussed that the damage condition in the vicinity of the notch or slit, and the crack initiation behavior affects the fatigue strength. Also, the S-N curve and fatigue limit was related to the crack growth in shear mode.