A tunable acoustic absorber using reconfigurable dielectric elastomer actuated petals

Abstract

Dielectric elastomer actuator (DEA)-based unimorphs that actively bend in one direction, can mimic the blooming motion of flower petals. Here we explore an application of such reconfigurable DEA to create tunable acoustic absorber capable of adapting to fluctuations in dominant noise frequency. The DEA-unimorphs consist of alternate layers of dielectric elastomers and compliant electrodes bonded to a Mylar sheet and were micro-slotted to form triangular petal-like structures that bend upon voltage activation. When arranged in an array, the micro-slotted dielectric elastomer bending actuators (MSDEBA) can open like flower petals, actively reconfiguring their open-ratio. Integrated with a base resonator comprising a micro-slotted panel (MSP) and a parallelly arranged varying-depth (VD) back-cavity, the MSDEBA forms a tunable acoustic absorber effective in the low-mid acoustic frequency range at inactive state. Meanwhile, upon voltage activation, it increased the absorber’s open-ratio and tuned the absorber to target a higher frequency. A 5 kV activation reconfigured the MSDEBA to shift its transmission loss peak by 72.74% (i.e., from 697 Hz to 1204 Hz). This acoustic spectrum tuning capability doubled the 15 dB absorption bandwidth of these absorbers from a bandwidth of ~435 Hz to 820 Hz. Such absorbers have the potential to tune the absorption spectrum to match the noise frequency in real-time to ensure optimal acoustic attenuation.