Control of Sound Pressure in a Piston-Pipe System using Active Compression Damping Treatment

Abstract

The sound pressure level in a one-dimensional piston-pipe enclosure is controlled using the Active Compression Damping (ACD) treatment. The ACD treatment, which is bonded directly to the driving piston, uses the compression and expansion deformations of visco-elastic material sandwiched between the electromagnet and a permanent magnet to dissipate the acoustic energy inside a piston-pipe system. ACD treatment is an active/passive hybrid controller. When the active part fails due to a malfunction of any element in the control circuits, the passive part still operates and gives acceptable control efforts. The behavior of the system is evaluated by monitoring the sound pressure level at the closed end of the pipe with single tone, two-tone and broad band noise excitations. Proportional and Derivative feedback control are used to activate the electromagnetic actuator. The results obtained indicate significant attenuation of the acoustic energy inside the pipe.