Auxetic hierarchical metamaterials with programmable dual-plateau energy absorption and broadband vibration attenuation

Materials or structures that integrate mechanical performance, lightweight as well as vibration attenuation remain a challenging endeavor. Auxetic materials and structures are promising candidates for the realization of this vision, namely, multifunctionality. However, developing the multifunctional properties of auxetic meta- materials rather than simply superposing components with different functions remains to be solved. To overcome these drawbacks, a novel auxetic re-entrant honeycomb based on the hierarchy strategy (HRH) is proposed in this work which not only can realize a dual-plateau mechanical response but also broad elastic wave bandgaps. The quasi-static and dynamic mechanical performances of the HRH are investigated numerically and experimentally. Then, we demonstrate the programmability of dual-plateau regions of the HRH by parametric studies. Additionally, experimental and numerical results of the band structures for the HRH reveal that the proposed structure exhibits broad bandgaps due to the local resonance mechanism and Bragg scattering. This work presents a new design paradigm for multifunctional metamaterials featuring customizable mechanical properties and vibration attenuation, and the results pave the way for the applications of multifunctional metamaterials.