Auxetic metamaterials as a rich platform for controlling acoustic and elastic waves in a programmable manner

In this work, we instigate the mechanics (both static and dynamic behavior) of a class of metamaterials with dynamically tunable properties. We consider three-dimensional basic building blocks (i.e., unit cells) with effective Poisson's ratios varying among positive, zero, and negative values. We analyze their effectiveness in controlling both elastic wave (vibrations) and airborne noise (sound) propagation in all-directions. Further, we investigate the effects of piezoelecticity to tune their band gap frequency ranges, even with the presence of various external mechanical loads.