Abstract:

Sound absorption and sound transmission of nonhomogeneous porous materials made of random or regular arrays of porous media is investigated using the finite-element method. The configuration studied consists of a column of porous materials inserted in an infinite rectangular waveguide. In the finite-element model, an equivalent fluid model for the porous material is coupled to the modal behavior in the waveguide. By comparison with analytical calculations, the difference between absorption mechanisms in three-dimensional porous patchworks and simpler stratified materials is investigated. In particular, the importance of nonpropagative mechanisms is enlightened. Also, the transmission loss performance of nonhomogeneous porous materials compared to homogeneous porous material is discussed. [Work supported by Bombardier, Inc., Canadair and NSERC.]