Increasing the Translaminar Fracture Toughness of Carbon Fibre Composites by Hybridising with High-Performance Polymer Fibres

The translaminar fracture toughness governs the damage tolerance and notch sensitivity of a composite material. A promising strategy to improve the translaminar fracture toughness is to hybridise brittle carbon fibres with tough fibres, such as highperformance polymer fibres. These fibres introduce an additional energy dissipating mechanism by fibrillating upon failure. However, the translaminar fracture toughness performance of the composites with these fibres has not yet been extensively reported in the literature. Compact tension tests were performed to analyse the translaminar fracture toughness of aramid and polyarylate (PAR) fibre composites. Carbon fibre composites were used as the reference. The laminates were produced by manufacturing prepreg and subsequently curing them in an autoclave. An appropriate sample design was set-up to perform the compact tension tests. The propagation translaminar fracture toughness of the PAR fibre composites was 492 kJ/m², significantly higher than the 39 kJ/m² of the carbon fibre reference. In contrast, the aramid fibre composite did not show a significantly higher toughness than the carbon fibre reference. Different design strategies have been examined. Having a strip of PAR fibres proved successful to locally slow down crack growth by increasing the translaminar fracture toughness. The results presented in this work allow to further optimise the design of composites for damage tolerance. These improvements can increase the safety of composite parts for society while also decreasing the weight of the part.