Coupling heavy fluid radiation effects to nonlinear vibrations analisys of structures

Abstract

This study is motivated by current issues in transportation acoustics, where the goal is to predict and reduce the noise radiated by vibrating structures. Potential applications include passive and active vibroacoustic control of extended sources. In this work, the vibration of structures is described by numerical techniques. Structures like beams and plates can be modeled by finite element techniques. Nonlinearities effects originated by large displacements formulation are use to describe the mechanical system. In this implementation, the dynamic model of the Von-Kármán equations is used and the solu- tions are projected over the linear modes of the structure. The structural system is coupled to the infinity fluid action. It was used one temporal formulation calculated by a convolution integral of the fluid ra- diation impedance and the champ of velocities of the mechanical system. The fluid-structure effects are extent to heavy fluid coupling. The goal of this work is put numerical simulation of sound radiated by vibrating structures including sound-structure coupling. The formulation is developed in the extended case including resonance modes and geometrical nonlinearities of the structure. Two geometrical config- urations of the plate were used. The results obtained by the numerical method using the present models are achieved and the influence of geometrical nonlinearities on sound radiation is explored. Firstly, the linear model was used to study the acoustic radiation influence on the dynamical responses. One second analysis was performed, using a nonlinear formulation. This way, the heavy fluid radiation effects on the nonlinearities were investigated.