Power Flow Control of a Thin Plate : Vortex-type Intensity and Structure-Borne Sound

Abstract

This paper deals with the active control of structure-borne sound radiating from a vibrating plate. It is the purpose of this paper to clarify the characteristics of the system response when the sound radiation is suppressed by controlling structural power flow. As a result of applying power flow control, the authors have already shown that there are basically three resultant response patterns in vibration intensity flow: straight, S-shaped and vortex. Relationships between the acoustic intensity and vibration intensity of these patterns are investigated in this paper. Particular emphasis is placed upon the vortex-type response pattern, which has the potential for realizing mode localization. A novel method for producing a power flow vortex at an arbitrary position on the plate is introduced. Furthermore, it is shown that there exists a situation where the direction of the acoustic intensity and vibration intensity vortices are completely opposite. It also turns out that there is a sound pressure null above the vortex center.