Response characteristics of a viscoelastic gel under the co-action of sound waves and an electric field

We design a flexible sound tunable sandwiched panel structure, which is composed of a nanoelectrorheological gel layer and two conductive rubber sheets, and experimentally investigate the tunable behaviors of the sound transmitted through the panel. For the frequency range of 380-500Hz the transmitted sound pressure level (SPL) decreases with the electric field strength E_e, while at about 550-650Hz the SPL increases with E_e. Within 500-550Hz a hump appears and the hump apex shifts in the high frequency direction with increase of E_e. Besides this, the phase angle of the transmitted sound wave changes with E_e within these frequency ranges. The weight fraction of particles in the electrorheological gels also influences these observed tunable characteristics. The theoretical calculation based on a vibration-radiation model agrees with the experimental results, qualitatively. It is revealed that the electric field induced viscoelasticity change in the electrorheological gel and hence the vibration-radiation variation on the sandwiched panel is the origin of the phenomenon. The flexible composite electrorheological panel could be used in sound sensitive artificial skins or sound tunable actuators and has potential for use in robots and intelligent structures and systems.