Quasi-static and high-rate flexural responses of intralaminar-hybridised basalt-flax fibre-reinforced polymer composites

With the rapid advancement in the design and manufacturing of fibre-reinforced polymer composites, the limited research on the high-rate dynamic flexural behaviour restricts the effective use of these materials in high-performance load-bearing applications. Sustainable composites made from intralaminar-hybridised basalt-flax fibres, along with their hybrids incorporating carbon fibres, were fabricated using vacuum assisted resin infusion technique. A modified Split-Hopkinson Pressure Bar technique was employed for the high-rate three-point bending tests, while the quasi-static flexural behaviour was assessed with an electromechanical universal testing machine. In-situ damage characterisation for the dynamic testing was analysed with the aid of high-speed camera footages. The strain rate effect and energy absorption capability were also analysed. The novel basalt-flax/carbon fibre-reinforced epoxy composite achieved an ultimate flexural strength exceeding 2000 MPa at a loading velocity of 30.5 m/s, which represents a 21% improvement over its pure carbon fibre-reinforced counterpart and a 93% improvement surpassing its carbon/basalt fibre-reinforced counterpart. Their superior dynamic flexural properties demonstrate great applicability of basalt and flax fibres as sustainable reinforcing fibres in high-velocity impact applications, especially in the automotive and aerospace industries.