Abstract: The appendages of mantis shrimp often bear bending loads from different directions during the in the process of preying on prey with its grazing limb. Hence, it has excellent bending resistance and isotropy to confront complex and changeable external load. The outstanding performance owes to the helical Bouligand structure with a certain interlayer corner, which is also widely found in other natural materials. Hence, the bio-inspired materials with basalt fiber are fabricated with outstanding bending resistance, isotropy and toughness. The research shows laminates with 18° interlayer corners exhibit relatively excellent bending resistance and isotropy, and the laminate with 11.25° interlayer corner has best toughness. Compared with traditional composites, average bending strength along different loading direction of bio-inspired materials increased by 28%, and anisotropy decreased by 86%. Besides, the maximum toughness of laminates can increase to 1.7 times of the original. Following the introduction of interlayer corners, the bio-inspired composite tends to be isotropic. To explore the reason for the change of the isotropic performance caused by diverse interlayer corners, the Finite Element Analysis based on classical laminate theory and Tsai–Wu and Tsai–Hill failure criterion. Besides, further experiments and observations are conducted to explore possible reasons. In conclusion, following the introduction of interlayer corners, the bio-inspired composites tend to be isotropic. This bio-inspired composites are expected to be applied to various complex modern engineering fields, such as vehicle, rail transit and aerospace.

Key words: Helical Bouligand structure, Bio-inspired composites, Bending resistance, Isotropy