Damage tolerance mechanism of bioinspired hybridization helical composite in lobster homarus americanus

A typical twisted laminar structure was an essential feature for the exoskeleton of the lobster Homarus americanus to resist impact damage and penetration. In fact, two kinds of helical structures were observed in the exoskeleton with different pitch angles and ply thicknesses in the exocuticle and endocuticle. It is worth investigating the evolutionary mechanism of the hybrid helicoidal structure rather than a single helix. In this paper, two pitch angles and ply thickness were introduced to reproduce the hybridization helicoidal structures of crustacean ectoskeletons. Numerical investigations were carried out, including low-velocity impact and compression after impact (CAI). The results showed that the bionic architectures need to balance the protection function provided by the endocuticle and load-carrying performance provided by the exocuticle. In addition, the qualitative relationship between design parameters and performance was analysed. The decrease in angle and the increase in layer thickness will lead to an increase in energy dissipation during the impact process and a decrease in residual strength. The research results provide a reference for the design of hybrid bionic structures with multimechanism cooperation.