A study on the relation between the actuator placement and the characteristics of the sound radiated by a plate structure

Abstract

One of the parameters influencing the performance of active control systems for the reduction of vibration or noise is the placement of the active components of the system (actuators) on the host structure. In active vibration control systems the actuators are normally placed following a criterion related to the kinetic energy on the structure, whereas in active noise reduction systems they are placed taking into account a sound pressure related metric. This numerical study investigates the placement of point force actuators on a generic plate structure within an active structural acoustic control system. Two setups are tested: a plate radiating in free field, and a plate radiating into a rectangular cavity. In both setups the plate is excited in its first natural frequencies by an incident diffuse sound field. The optimal placements of the actuators on the plate determined for a minimal sound power radiated in free field or a minimal acoustic potential energy radiated into the cavity are compared to the optimal actuator placements determined for a minimal mean loudness over the area of interest. The effect of the different actuator placements on the ttenuation of the dominant radiation modes is analysed. The possible benefits of using the psychoacoustic loudness as an actuator placement criterion are discussed.