Vibration control of curved piezoelectric sheets using negative capacitance circuits

Sound-induced vibrations of a curved PZT fiber composite sheet have been controlled by a negative capacitance circuit. A laser Doppler vibrometer was used to measure the vibration amplitude. The estimated value of the sound transmission loss was increased up to 85 dB by operating this circuit from 60 dB. The controllable frequency range was increased by using another composite sheet as a capacitor. When compared with the case of a curved PVDF film, the required voltage amplification was reduced to 1/20 because the electromechanical coupling factor was five times greater.