Adaptive-passive control of noise radiation of gear-box systems using a pair of shunted piezo-based rotating inertial actuators

In this paper, two Piezo-Based Rotating Inertial Actuators (PBRIAs) are considered for the suppression of the structure-borne noise radiated from rotating machinery. Each inertial actuator comprises a piezoelectric stack element shunted with the Antoniou's gyrator circuit. This type of electrical circuit can be used to emulate a variable inductance. By varying the shunt inductance it is possible to realize two tuneable vibration neutralizers in order to suppress single frequency vibrations of a slowly rotating shaft. As a consequence, reductions in the sound radiated from the machine housing can be also achieved. First a theoretical study is performed using a simplified lumped parameter model of the system at hand. The simplified model consists of a rotating shaft and two perpendicularly mounted shunted PBRIAs. Secondly, the shunted PBRIA is tested on an experimental test bed comprising a rotating shaft mounted in a frame. The noise is radiated by a plate that is attached to the frame. The experimental results show that a reduction of 11 dB on the disturbance force transmitted from the rotating shaft through the bearing to the housing can be achieved. This also generates a reduction of 9 dB for the plate vibration and the radiated noise.