Interlaminar fracture toughness of selectively stitched thick carbon fibre reinforced polymer fabric composite laminates

Carbon fibre reinforced polymer fabric specimens prepared from selectively stitched thick laminates have been tested under mode I(tension) and made IT (shear) loading, similar to already established tests used for thin unidirectional specimens. The respective interlaminar fracture toughness characteristics were derived for laminates of different stitching configurations. Results indicated significant interlaminar fracture toughness increase for all stitched samples compared with non-stitched samples, especially under mode I loading. It was concluded from parametric investigations that carbon thread stitching is more effective than its aramid counterpart in improving interlaminar fracture toughness. This is attributable to its higher stiffness and better bonding to the carbon fibre reinforced polymer system compared with the aramid thread. The testing methodology, which was developed successfully in the present research, is recommended for use for interlaminar fracture toughness characterisation of thick, carbon fibre reinforced polymer laminates. PRC/1539.