A review of helicoidal composites: From natural to bio-inspired damage tolerant materials

Helicoidal composites have been found in shrimp club, lobster claw, beetle cuticle, crab shell, scorpion pincer, and fish scale as a natural material. The helicoidal composite possesses excellent impact resistance and extraordinary damage tolerance due to its hierarchical structure and the unique helicoidal arrangement of its reinforcement fibres. Its structure and performance have been studied through various characterisation and mechanical testing methods. Based on the structure-property relationship of the natural helicoidal composite, researchers have been able to mimic the unique fibre arrangement and develop bio-inspired helicoidal composites with enhanced impact performance. Various helicoidal composites comprising of synthetic fibrous materials such as carbon fibre (CF), glass fibre (GF), and aramid fibre, and matrix materials such as thermoset and thermoplastic polymers have been developed through biomimicry. The failure mechanisms of the bio-inspired helicoidal composites have been studied and the advantages of arranging the fibre reinforcement into helicoidal architectures have been elucidated over conventional composite constructions such as quasi-isotropic (QI) and cross-ply layups. This review systematically elaborates the recent progress of the research work on both natural and bio-inspired helicoidal composites. It sheds light on the distinctive construction of the natural helicoidal composites found in different animals such as shrimps, lobsters, crabs, beetles, scorpions, and fish, and their energy absorption mechanisms. Different manufacturing methods for developing bio-inspired helicoidal composites are discussed and various reinforcements and matrix materials used in the composites are described. The processing-structure-property interrelationship of the bio-inspired helicoidal composites is summarised. This review will contribute to the advancement of the knowledge of the natural helicoidal composite and potentially help researchers to develop highly efficient bio-inspired damage tolerant helicoidal composites.