A new modeling of thin poro-elastic control layer used for optimizing the acoustical performance of lightweight materials

摘要

The demand for lightweight materials requires elaborate predictive models in order to ensure that the acoustical performance of vehicle components is not compromised when developing a sound package. When various composite layers are bonded together, the control of parameters such as airflow resistance and density provides a proper balance between transmission loss and absorption. This could be achieved by the proper choice of a poro-elastic dense layer. The interface conditions in such a composite can become quite complex. In recent papers [Woodcock & Ebbitt SAE 2001, Woodcock et al. Noise Con 01] a new conceptual formulation has been proposed in order to deal with such systems. This is a Pseudo-Macroscopic Approach (PMA) in the framework of the four-pole theory. In the present paper, a new model, namely PEM.SISO is proposed. This is based on the electrical SISO circuit. The main assumption of this modeling is that the pores of the material are not necessarily opened to the exterior and their size is very small compared to the wavelength. This causes the material to exhibit a global behavior of structural type. The paper shows that the absorption can be significantly improved in low frequencies by adding stiffness at the interfaces.