Lessons from Nature for Carbon-Based Nanoarchitected Metamaterials.

Bioinspired materials often achieve superior mechanical properties owing to their microscale architectures that resemble design motifs in biological materials. The bioinspired architectures can be extended to nanoscale, where carbon-based materials, including graphene and carbon nanotubes, are excellent candidates as building blocks. This study introduces carbon-based nanoarchitected metamaterials inspired by seven biological design motifs, i.e., cellular, gradient, tubular, fibrous, helicoidal, suture, and layered structures. Numerical studies based on molecular dynamics simulation along with continuum-based finite element analysis are conducted for each bioinspired design to examine the unique mechanical properties, namely specific stiffness, specific strength, failure strain, and specific energy absorption, under tensile/shear loading conditions. Different deformation and failure mechanisms found by molecular simulation and continuum mechanics are discussed. The numerical results show that the mechanical properties of the introduced bioinspired and carbon-based nanoscale designs may surpass the performance of the conventional carbon-based counterparts. The developed nanoarchitected metamaterials demonstrate instances of possibilities for filling the empty regions in the Ashby charts to attain lightweight advanced materials that can also break the trade-off between strength and failure strain. These findings impart lessons from the constitutive structure of biological materials to form the next generation of multifunctional architected metamaterials with rationally designed nano-architectures.