Reduction of Structural Acoustic Radiation Via Left and Right Eigenvector Assignment Approach

Abstract

The objective of this research is to investigate the feasibility of utilizing a new left—right eigenvector tailoring method in reducing the acoustical radiations of flexible structures. The structural sound pressure radiation can be expressed in terms of a combination of vibration modes, where its magnitude is also a function of the external disturbance distribution. In other words, the radiated sound pressure level depends on both the right eigenvectors (related to the structural mode shapes) and left eigenvectors (related to the system disturbance rejection ability) of the vibrating structure. The basic idea of the proposed approach is to simultaneously modify the structural modal velocity distribution and the system capability of disturbance rejection through active left—right eigenvector assignment control actions, so that the sound pressure radiated from the vibrating structure can be reduced. Numerical simulations are performed to evaluate the effectiveness of the proposed method on structural noise reduction. Frequency responses of sound pressure at a receiver in the selected frequency range are illustrated. It is shown that with the proposed active control method, one can re-shape the modal velocity distribution and enhance disturbance rejection, and hence can effectively minimize the structural sound pressure radiation.