Aligned discontinuous carbon fibre tows in hybrid composites and their tensile behaviour: an experimental study

Abstract

The paper aims to explore potential higher value applications of discontinuous carbon fibre tows. A vibration-assisted dry alignment method is presented to align the discontinuous fibre tows between conventional dry reinforcement mats/fabrics to fabricate cost-effective hybrid composites. Its viability is demonstrated by successful fabrication of two hybrid composite panels, where thin layers of aligned 12 mm discontinuous carbon fibre tows were deposited between E-glass chopped strand mats or woven fabrics respectively, via an out-of-autoclave resin infusion process; 54% and 81% of the fibre tows were aligned in the range of ±5° and ±10°, respectively. The tensile test results clearly demonstrate the importance of having the discontinuous fibre tows highly aligned in the hybrid composites, which shows increased stiffness (up to 24.4%) and strength (up to 59.9%) over the non-aligned hybrid composites. The aligned hybrid composites also exhibit a non-linear pseudo-ductile response due to subcritical progressive damage compared to the catastrophic brittle failure of the baseline non-hybrid E-glass and non-aligned hybrid composites, despite the tensile strength knockdown (up to −40.3%) due to premature inter-tow debonding. They also display increased stiffness up to 90%.