Physics

Mathematics

Acoustic attenuation

Poisson distribution

Optics

Statistics

Metamaterial

Poisson's ratio

Composite material

Vibration

Acoustic metamaterials

Acoustics

Attenuation

Materials science

Optoelectronics

Auxetics

Applied Physics Letters

Through a combination of analytical, numerical, and experimental methods, we study a three-dimensional metamaterial with the ability to attenuate both airborne sound and mechanical vibrations, simultaneously, and in all directions. In addition, due to the auxetic nature of the design (i.e., having a negative Poisson's ratio), the metamaterial can shrink (or expand) in a relatively uniform manner, without buckling. We utilize an external load to cause a systematic shape change in the metamaterial and tune the attenuation frequency bands. The presented design principles can be utilized in many applications related to acoustic and elastic wave manipulation as well as acoustic devices.

Tunable auxetic metamaterials for simultaneous attenuation of airborne sound and elastic vibrations in all directions