Wave transmission reduction by a piezoelectric semi-passive technique

This paper deals with the so called SSD (stands for Synchronized Switch Damping) technique that is a semi-passive approach developed to address the problem of structural vibration damping and noise reduction. Compared with standard passive piezoelectric damping, this technique offers the advantage of self-adaptation with environmental variations (e.g. temperature, pressure, etc.). Contrary to the active damping systems, its implementation does not require any sophisticated signal processing or any bulk power. In the semi-passive approach, the piezoelectric element is continuously switched from open circuit to specific impedance synchronously to the strain. Due to this switching mechanism, a phase difference appears between the strain induced by an incident acoustic wave and the resulting voltage, thus creating energy dissipation. In this non-linear process, damping performances directly depend on the electromechanical coupling coefficient of the system. In the weakly coupling systems, the piezoelectric element voltage amplitude can be artificially increased by switching on voltage sources. Using this method (Synchronized Switch Damping on Voltage source, SSDV), a 16.1 dB attenuation on the transmitted wave pressure in the tube is obtained whereas only 8 dB is achieved with the classical SSD. Furthermore, as this method is adaptive, attenuation is observed over a 600 Hz wide frequency band.