The effect of binder path on the tensile properties and failure of multilayer woven CFRP composites

An investigation has been carried out on the in-plane tensile properties of two orthogonally woven structures with different binder paths. Measurements were made along both the longitudinal (warp) and transverse (weft) axes on samples manufactured from two commercially available carbon fibres which are known to have different resistance to fibre damage induced through weaving. In general, this research revealed that the more damage-resistant fibre produces composites with higher strength and stiffness. It was also found that, independent of the fibres used, the in-plane fibre yarns in the structure with the longer binder path are less crimped and this, by and large, translates to better or unchanged tensile modulus, strength and strain-to-failure. In addition to fibre fractures, the superior strength of this composite was also observed to promote an extensive amount of longitudinal splitting, thus resulting in a relatively large failure zone. In the structure with the shorter path length where the in-plane fibres are more crimped, failure is due predominantly to fibre fractures. Groups of fibres are pulled out during failure of both structures, despite good fibre wetting and fibre/matrix adhesion having been achieved with either fibre.