Experimental Characterization Of Failure Behaviour For Three-Dimensional Woven Carbon/Carbon Composites Under Pin-Loading

An experimental approach of three-dimensional woven carbon/carbon composites arranged in various geometrical configuration is presented in this paper. Seven types of samples divided into three groups were tested under pin-loading to determine the effects of width-to-hole diameter ratio (W/D), edge distance -tohole diameter ratio (E/D) and hole diameter -tothickness ratio (D/t) on the failure mode. For an advanced understanding of failure propagation, damage mechanism was observed and assessed combining acoustic emission monitoring. The experimental results and observations indicated that net-tension failure and shearing-out failure switched to bearing failure with the increasing ratio of W/D and E/D, respectively. while D/t hardly affected the failure mode. Major features of the damage mechanisms included matrix crashing and cracking, fiber microbuckling and bending, interface debonding and fiber breakage with different acoustic emission signal ranges.