Tunable acoustics with dielectric elastomer activated granular jamming exhibiting a solid–fluid transition

Abstract

Acoustic metamaterials, which manipulate acoustic propagation using architected, discrete structures, have wide ranges of applications but typically have a fixed response upon design and fabrication. We present a novel tunable acoustic structure with a granular jamming-based approach, where the jammed state acts as a solid with a well defined resonant response and the unjammed state acts as a liquid with a broad, weakly resonant response. In between these two extremes, resonance peak tuning is observed. Our approach to particle jamming is uniquely controlled with a dielectric elastomer actuator (DEA), whose applied confining pressure is governed by voltage. Mathematical modeling of the DEA and the confining pressure is used to understand the device behavior. Samples are fabricated and tested acoustically, revealing a novel solid–liquid like transition at an applied voltage of about 6.0 kV and a preceding “rattler” behavior at around 4.25 kV.