EXPERIMENTAL CHARACTERIZATION OF MODE-II INTERLAMINAR FRACTURE AND CRACK ARRESTMENT IN GEOMETRICALLY SCALED STITCHED RESIN-INFUSED COMPOSITES UNDER THERMAL LOADING

This study investigates the enhanced mode-II interlaminar fracture toughness of stitched carbon fiber-reinforced plastics (CFRPs) for aerospace applications under high-temperature conditions and geometric size effects. For the experimental work, two different sizes of end-notched flexure (ENF) specimens were manufactured and tested using a three-point bending configuration. Additionally, three different temperature scenarios were designed using a heat gun and a heating chamber. The experimental data showed that the mechanical properties of the ENF specimens could be degraded under high-temperature environments. It was also shown that stitching is effective in preventing mechanical property degradation under different temperature regimes and geometric scales at different extents. Lastly, optical microscopic images revealed different types of delamination patterns in different geometric scales and the robustness of stitching yarns under mode-II interlaminar fracture conditions. Therefore, through-thickness stitching could contribute to enhancing the structural integrity of CFRP parts and structures subject to high-temperature conditions. For the aerospace applications of stitched composites under extreme environments, further study will be done to investigate the impact of different delamination patterns in geometrically-scaled stitched CFRPs on crack arrestment under high-temperature regimes.