Recent advances in the defense, aerospace, and energy industries have triggered tremendous demand for multifunctional materials featuring lightweight, load-carrying capacity, and thermal resistance. Metamaterials with artificially engineered architectures can be exploited to provide a compelling combination of these properties. Here we report a group of hierarchically architected metamaterials constructed by replacing cell walls of regular honeycombs with hexagonal, kagome, and triangular lattices, respectively. Our numerical and analytical studies indicate that the introduction of structural hierarchy in regular honeycombs results in improved heat resistance and thermal anisotropy. These thermal properties can be controlled by tailoring two geometric parameters of the hierarchical honeycombs. We also predict that the hierarchical honeycombs with kagome and triangular lattices exhibit enhanced mechanical properties. Our analysis reveals that the integrated thermal mitigation and load-carrying capacity of the hierarchical honeycombs are attributed to the introduction of structural hierarchy. The hierarchical metamaterials reported here provides new opportunities to design multifunctional materials that are promising for various engineering applications.
