Locally programmable metamaterial elements using four-dimensional printing

Abstract

Within the area of acoustic metamaterials, the field of tunable acoustic structures has gained a large amount of interest for their ability to adapt to a wide range of frequencies. In this work, we explore the intersection of tunable acoustic structures and additive manufacturing by 4D printing a metamaterial element whose acoustic response can be locally, actively tuned via resistive heating. Contrary to existing, thermally tunable structures, which rely on ambient heating for elastic modulation, the 3D printed structure presented here can be precisely controlled to selectively soften or stiffen only desired areas of the structure. We demonstrate this by tuning the acoustic response of membrane structures since many acoustic metamaterial phenomena utilize membrane geometries. Specifically, we present three geometries of tunable membranes, a structure which decreases frequency response upon heating, a structure which increases frequency response upon heating, and a structure which exhibits non-axisymmetric acoustic mode response from normal incident plane waves.