Quasi-static evaluation of mechanical properties of poroelastic materials: Static and dynamic strain dependence and in vacuum tests

A complete description of the vibro-acoustical behavior of a poroelastic material requires the knowledge of both geometrical quantities, related to the structure of the fluid-filled pores to account the sound propagation within them, and mechanical parameters (i.e. Young's Modulus, Poisson ratio and loss factor) in order to model the wave propagation through the elastic structure constituting its skeleton. Because the non-linear nature of poroelastic media, these mechanical properties are observed to depend on static preload and dynamic strain applied to them. In the present work well established quasi-static methods, based on the measurement of mechanical impedance and the use of adequate polynomial relations, have been used to determine the dependence of the mechanical properties on the applied deformations. Furthermore, tests have been also carried out in a vacuum chamber in order to evaluate the real contribution of the filling fluid on the total vibro-acoustical response of the material.