Polynomial relations for quasi-static mechanical characterization of isotropic poroelastic materials

This paper proposes a quasi-static method for the characterization of the elastic properties of poroelastic materials. The method is based on the development of polynomial relations among compression stiffness, Young's modulus, Poisson's ratio, and shape factor derived from high order axisymmetrical finite element simulations on a disk-shaped poroelastic sample under static compression. The shape factor is defined as half the radius to thickness ratio of the sample. The polynomial relations account for the fact that the disk sample "wants" to bulge sideways when compressed between two rigid plates on which it is bonded. A compression test setup is used to measure the compression stiffness of two disk samples of different large shape factors. The measured stiffnesses together with the polynomial relations lead to a system of two equations and two unknowns. The solution of the system yields the Young's modulus and Poisson's ratio of the poroelastic material. Employing the proposed quasi-static method, Young's modulus, Poisson's ratio, and loss factor are measured for a poroelastic foam. The measured elastic properties are used in the Biot poroelasticity theory to predict the sound absorption coefficient of the foam. The prediction is finally compared with a standing wave tube measurement. A good correlation is obtained. (C) 2001 Acoustical Society of America.