Coupled FEM/BEM approach for analysis of sound transmission through stiffened plates

The computational model of sound transmission through a stiffened plate excited by a harmonic oblique incident plane wave and mounted in an infinite baffle using the coupled finite element/boundary element approach is presented. The finite element method is used to model the structure and the boundary element method based on the Rayleigh integral on the plate surface is employed for the acoustic fluid. The proposed model takes the acoustic fluid-structure coupling into account. The sound transmission losses through stiffened plates are calculated and discussed with the proposed model. The numerical results show that: the sound transmission losses are closely dependent on the natural frequency of the structure and the excitation frequency and it is important to detune the structural resonant frequency away from the excitation frequency; the position of minimum values of the sound transmission losses curve varies with the changes of the structural nutural frequencies after modifying plate thickness and moment of inertia of stiffeners; an increase in the plate thickness or the moment of inertia of stiffeners reduces the sound transmission through stiffened plates markedly from air to air and mildly from air to water.