Active control of a coupled plate-cylinder system

Abstract

An analytical expression for the sound pressure radiated into the far-field by a coupled plate-cylinder system is derived. The system is composed of a rigid plate mounted inside a finite length simply-supported cylindrical shell via a fixed number of active-passive mounts. A harmonic point-force disturbance is applied to the plate. Various active control approaches are applied to minimize the acoustic pressure radiated by the coupled system. The Active Structural Acoustic Control (ASAC) approaches include the control of the acoustic pressure in one or several directions of radiation, the control of the total radiated power, the control of the power radiated in a sector and the control of selected components associated with circumferential cylinder modes. The Active Vibration Control (AVC) approach is the control of the radial vibration at the points of attachment of the mounts on the cylinder. Numerical calculations show that the radiated pressure can be controlled using active-passive mounts for all these approaches. However, comparisons in terms of control efficiency and control effort show that ASAC yield better results than AVC. Moreover, ASAC enables directional control of sound and AVC does not. Opposed and parallel active-passive mount configurations are compared. The results show that the first arrangement requires much larger control forces on-resonance, but the two methods show similar performance off-resonance.