Towards the placement of actuators and sensors for an active control of structure-borne sound in a stiffened rectangular panel

Abstract

The active control of structure-borne sound proposes an alternative approach towards the global reduction of vibration and noise. By actively reducing or blocking the energy flow from upstream noise sources, e.g. engines or APUs of an aircraft, inside a structure, acoustically relevant downstream section of a system, e.g. the passenger cabin, may be attenuated. This work deals with a numerical analysis towards the placement of actuators and sensors on a simple stiffened structure in order to achieve a reduction in energy flow, continuing recent research on the topic for simpler plates, where advantages of the approach could be shown already. A set of virtual error sensors is used to measure the components of structural intensity on either the shell or stiffening elements. A feed-forward control is used to drive pairs of control forces to minimize those components and, hence, overall energy transmission. It can be shown that an inclusion of internal forces can achieve a greater global reduction in vibration compared to a simple velocity control also for a stiffened plate. By using structural intensity or its components, a greater reduction of downstream vibration can be achieved using a less dense array of sensors respective to the sound wavelength.