Mode I interlaminar fracture toughness properties of advanced textile fibreglass composites

The Mode I interlaminar fracture toughness properties of vinyl ester-based composites reinforced with fibreglass manufactured by the advanced textile technologies of braiding, knitting, stitching and through-the-thickness wea ving are assessed in comparison to a variety of traditional composites made from fibreglass such as unidirectional or woven rovings. The interlaminar fracture toughness (G(Ic)) of braided and knitted composites are higher tha n traditional composites by factors of more than two and four, respectively . Toughening in these textile composites was caused by extensive crack bran ching as the interlaminar crack was forced to follow a tortuous path throug h the complex fibre architectures. The G(Ic) values of the composites reinf orced in the through-thickness direction by weaving or stitching were highe r than traditional composites by factors of nearly two and three, respectiv ely, with the main toughening mechanism being crack bridging by the through -thickness binder yarns/stitches. A review of Mode I interlaminar fracture data collected from papers shows that advanced textile techniques are capab le of manufacturing composites with substantially improved delamination res istance. (C) 1999 Elsevier Science Ltd. All rights reserved.