Bamboo-inspired, simulation-guided design and 3D printing of light-weight and high-strength mechanical metamaterials

Mechanical metamaterials, consisted of periodic arrangements of struts, exhibit excellent specific mechanical properties (kN•m/kg) and are of importance for aerospace applications, lightweight construction, bone implants, and energy absorption. However, current mechanical metamaterials are still falling far behind many biological architectures. On the other hand, biological materials often lack design flexibility and controllable structures, and mechanical performances. Here, inspired by the strong and ductile bamboo with a hollow architecture, we constructed three face-centered cubic (FCC) lattice-based mechanical metamaterials via selective laser melting of Ti-6Al-4 V with high fidelity. Guided by the numerical simulation, these biomimetic structures can be easily tailored through tuning the outer and inner (hollow) diameters with widely adjustable performances, resulting in a high compressive specific strength (87.19 kN•m/kg) at a low density (1.25 g/cm3) without losing isotropy in the octet-truss configuration (di=0.59 mm, do=1.10 mm). Our study, therefore, provides a biomimetic strategy to realize simultaneously light-weight and high-strength mechanical metamaterials with a hollow topology.