Mode hybridization in DNA-inspired helical metamaterials with variable centro-asymmetry

We study helical acoustic metamaterials and demonstrate the ability to vary the materials' dispersion properties by controlling geometrical structure and mass distribution. By locally adding eccentric, higher density elements in the unit cells, we perturb the moment of inertia of the system and introduce centro-asymmetry. This allows controlling the degree of mode coupling and the width of subwavelength bandgaps in the dispersion relation, which are the product of enhanced local resonance hybridization. We characterize the distinct normal modes in our metamaterials using finite element simulations and analytically quantify the coupling between each mode. The evolution of acoustic bandgaps induced by the increasing level of centro-asymmetry is experimentally validated with 3D-printed structures. ; © 2022 Author(s). Published under an exclusive license by AIP Publishing. Submitted: 29 June 2022 • Accepted: 01 July 2022 • Published Online: 15 August 2022. C.D. and G.K. acknowledge the support from the National Science Foundation (Grant No. NSF EFRI 1741565). K.C. acknowledges the support from the Summer Undergraduate Research Fellowship program. The authors are grateful to Paolo Celli and Brian Kim for their valuable discussions. See the supplementary material for the derivation of the analytical model and the discussion on the hybridization phenomena. Author Contributions. Gunho Kim: Conceptualization (equal); Formal analysis (equal); Investigation (equal); Methodology (equal); Software (equal); Validation (equal); Visualization (equal); Writing – original draft (equal); Writing – review and editing (equal). Kaila M. Y. Coimbra: Conceptualization (lead); Investigation (supporting); Methodology (supporting); Software (supporting); Visualization (equal); Writing – original draft (equal); Writing – review and editing (equal). Chiara Daraio: Funding acquisition (equal); Project administration (equal); Supervision (equal); Writing – original draft (equal); Writing – review and editing (equal). DATA ...