Study on impact and flexural mechanical properties of biomimetic laminated composites based on the hierarchical structure of plant fiber cell walls

Over billions of years of evolution, biological materials have developed diverse and efficient compositional structures, endowing them with outstanding comprehensive mechanical properties. These natural designs serve as a rich source of inspiration for enhancing the strength and toughness of composite materials. In this study, inspired by the hierarchical structure of plant fiber cell walls, we conducted research on the structural design and mechanical performance of biomimetic composites. Using the heterogeneous structure of the cell wall and the helical microfibril arrangement in the S2 layer as templates, two types of biomimetic laminated composites were designed and precisely fabricated via continuous fiber 3D printing. The results show that the impact strength of the biomimetic heterogeneous composite reached 65.5 kJ/m², representing a 35.7% improvement over the conventional structure. When the fiber helix angle was 30°, the specific bending energy absorption of the biomimetic helical composite reached 1.32 J, which is 50% higher than that of the unidirectional 0° laminated composite. Microstructural characterization validates that crack deflection and extended propagation paths are the mechanisms behind the synergistic enhancement of strength and toughness in the biomimetic structures. This work provides a viable pathway for developing composite structures with combined high strength and toughness.