Acoustic response of a curved active PVDF-paper/fabric speaker for active noise control of automotive interior noise

Knitted elastomeric fabrics can be made to vibrate as a speaker by laminating them with polyvinylidene fluoride (PVDF) strips to form a curved arch clamped at the ends. The tightly knitted structure of the elastomeric knitted fabric, which is void of pores, makes it an ideal membrane suited for a speaker. The PVDF strip would vibrate due to the piezoelectric effect when a 200 Vrms voltage is applied. In this work a two-dimensional analytical prediction model is created based on the principles of stress and strain behaviour of a curved laminated arch. The model predicts the radial displacement of the arch with respect to the frequency of the excitation voltage of the PVDF strips. The sound propagation level (SPL) at a particular point from the arch surface is modelled as a simple sound source in an infinite baffle. The acoustic pressure is then linked with the radial displacement in the model. Simulation and experiments are then carried out on structural properties of the elastomeric knitted fabrics to discern the resonance region of the speaker vital for active noise control to reduce automotive interior noise.