Finite Element Modelling of Vibro-Acoustic Systems for Active Noise Reduction

Abstract

Over the past years a lot of scientific work has been done in the field of smart lightweight structures to reduce the structural vibrations and the radiated sound. In the paper a virtual overall model of adaptive vibro-acoustic systems, completely based on the finite element method (FEM), is presented. Beside the passive structure, this model contains the active piezoelectric elements, the acoustic fluid, the vibro-acoustic coupling, and the controller influence. According to the requirements of an effective numerical analysis of thin walled structures, the coupling between active layered shell elements and acoustic 3D hexahedron elements is implemented. It is possible to take into consideration the interior as well as the exterior radiation problem. Because of the large number of degrees of freedom of the FE model, a modal truncation technique based on a complex eigenvalue analysis is performed. After transforming the model into the state space form, the Matlab/Simulink software is used to design an appropriate controller. To show the accuracy and the performance of the developed software approach, a vibrating elastic plate and the resulting sound field are numerically investigated.