Adaptive Helmholtz resonator based on electroactive polymers: modeling, characterization, and control

This paper presents a new concept and strategy allowing adaptive control of a membraned Helmholtz resonator (HR) embedded in a melamine foam. The designed system aims to adapt the acoustic absorption performances and transmission loss in low frequencies (<500 Hz). The proposed concept consists in replacing the resonator front wall by an electroactive polymer membrane. The stiffness of the membrane can be controlled by an electric field, resulting in a resonance frequency shift. A 2D axisymmetric numerical model based on the finite elements method is developed to characterize the complex structure-acoustic coupling between the membrane, the HR and the host foam to determine the potential of the concept. Experimental measurements are then performed in an impedance tube and compared to numerical results. A feedforward algorithm based on neural networks allows the adaptivity of the membraned HR to the acoustic excitation variation inside the impedance tube.