The effect of weave pattern and crack propagation direction on mode I delamination resistance of woven glass and carbon composites

The effect of weave structure on the interlaminar fracture behavior of orthogonal woven fabric composite laminates has been examined. Crack propagation along the fill and weft yarns, respectively, was considered for plain, twill and 8H-satin glass/epoxy composites, and a SH-satin carbon/epoxy composite. Fracture testing employed the mode I fracture DCB test specimen. Microscopic details of crack growth in the interply region were considered after fracture testing. The delamination resistance and the difference in fracture toughness between the fill and weft directions increased with increased weave index. Partial debonding of transversely oriented yams contributed to the delamination resistance. Fracture of debonded fibers referred to as 'fiber bridging' was observed in the twill and satin weave glass/epoxy composites, but not in the plain weave glass/epoxy and the SH-satin weave carbon/epoxy composites. The interlacing of the yarns limited the extent of fiber bridging. (C) 1998 Elsevier Science Ltd. All rights reserved.