Harnessing structural hierarchy to design stiff and lightweight phononic crystals

In this letter we report a class of hierarchically architected honeycombs in which structural hierarchy can be exploited to achieve prominent wave attenuation and load-carrying capabilities. The hierarchically architected honeycombs can exhibit broad and multiple phononic band gaps. The mechanisms responsible for these band gaps depend on the geometric features of the hierarchical honeycombs rather than their composition. Furthermore, the introduction of structural hierarchy also endows the hierarchical honeycombs with enhanced stiffness. We predict that the proposed hierarchical honeycombs can realize a unique combination of wave attenuation and load-carrying capabilities, thereby providing opportunities to design lightweight and stiff phononic crystals for various engineering applications.