Evaluation of the sound reduction index of flat panels through FE models accounting for fluid-structure interaction: Stochastic versus plane wave superposition methods

Abstract

This work presents an efficient procedure to predict the sound reduction index (SRI) of a flat panel of arbitrary internal complexity starting from numerical finite element (FE) simulations. This hybrid analytical-FE procedure allows to perform narrow band calculations considering fluid coupling up to high frequencies. The exciting sound field is synthesised considering a series of uncorrelated plane waves impinging on the panel. A stochastic approach based on the sinc function is also considered. A test case is presented in which the hybrid approach is applied to a glass panel. Computation time and memory consumptions are compared for the different implementations, showing that the stochastic approach requires considerably larger resources than the plane wave formulations. The method is validated against predictions by analytical methods and experimental data from sound transmission suites. To match the experimental results, the angle of incidence is limited to the value of 75∘, whose origin is discussed by means of ray-tracing simulations of the sound field distribution in the source room. It is found that the quality of the predictions can be improved by including the actual characteristics of the sound field in the plane wave formulation. If compared to a commercial full FE software, the proposed hybrid procedure features greatly reduced computational time, and results closer to the experimental values in the entire frequency range of interest.