Numerical Investigations on a Tunable Helmholtz Resonator: Integration of a Passive Polymer Membrane in a Helmholtz Resonator

A Helmholtz resonator is a passive acoustic resonator used to control a single frequency resulting from the cavity volume and the resonator neck size. The main purpose of work in progress is to propose to investigate numerically some strategies allowing real-time tunability of the Helmholtz resonator in order to provide a wider bandwidth and hence enhance noise attenuation. Two concepts will be developed, both based on the use of electroactive polymer (EAP) membranes. These materials exhibit a change of shape when stimulated by an electric field. The first concept consists in replacing the resonator rigid back plate by an EAP material membrane, while on the second one, the membrane is located in front of the resonator. Numerical investigations are performed using several kinds of a passive EAPs material membranes in order to determine the practical potential of these concepts. Significant enhancements of the transmission loss and/or the absorption properties could be obtained in the low frequency band by tuning the volume and then the resonance frequencies of the resonator. In the current paper, only the passive performances of these two concepts are discussed.