Tunable vibro-acoustic metamaterials

Phononic crystals and acoustic metamaterials are architected lattices designed to control the propagation of acoustic or elastic waves. In these materials, the dispersion properties and the energy transfer are controlled by selecting the geometry of the lattices and their constitutive material properties. Most designs, however, only affect one mode of energy propagation, transmitted either as acoustic airborne sound or as elastic structural vibrations. Here, we present a design methodology to attenuate both acoustic and elastic waves simultaneously in all polarizations. We experimentally realize a three-dimensional load-bearing architected lattice, composed of a single material, that responds in a broadband frequency range in all directions and polarizations for airborne sound and elastic vibrations simultaneously. In addition, we show how we can tune the vibro-acoustic response of the metamaterial through external stimuli.