Department of Mechanical Engineering, Virginia Tech, 635 Prices Fork Road, Blacksburg, VA, 24061, USA.
Sci Rep. 2018 Jun 14;8(1):9139. doi: 10.1038/s41598-018-26980-7.
Nature has evolved with a recurring strategy to achieve unusual mechanical properties through coupling variable elastic moduli from a few GPa to below KPa within a single tissue. The ability to produce multi-material, three-dimensional (3D) micro-architectures with high fidelity incorporating dissimilar components has been a major challenge in man-made materials. Here we show multi-modulus metamaterials whose architectural element is comprised of encoded elasticity ranging from rigid to soft. We found that, in contrast to ordinary architected materials whose negative Poisson's ratio is dictated by their geometry, these type of metamaterials are capable of displaying Poisson's ratios from extreme negative to zero, independent of their 3D micro-architecture. The resulting low density metamaterials is capable of achieving functionally graded, distributed strain amplification capabilities within the metamaterial with uniform micro-architectures. Simultaneous tuning of Poisson's ratio and moduli within the 3D multi-materials could open up a broad array of material by design applications ranging from flexible armor, artificial muscles, to actuators and bio-mimetic materials.
大自然通过在单一组织中耦合从几 GPa 到低于 KPa 的可变弹性模量，进化出了一种实现不寻常机械性能的反复策略。能够生产具有高度保真度的多材料、三维（3D）微结构，其中包含不同的组件，这一直是人造材料的主要挑战。在这里，我们展示了多模量超材料，其建筑元件由编码弹性组成，范围从刚性到柔软。我们发现，与普通的结构材料不同，其负泊松比由其几何形状决定，这些类型的超材料能够显示出从极端负到零的泊松比，而与它们的 3D 微观结构无关。由此产生的低密度超材料能够在具有均匀微观结构的超材料内实现功能梯度、分布式应变放大能力。在 3D 多材料中同时调整泊松比和模量，可以为从柔性装甲、人造肌肉到执行器和仿生材料等各种设计应用开辟广泛的材料选择。
