DYNAMIC BEHAVIOR OF POROUS-MEDIA SATURATED BY A VISCOELASTIC FLUID - APPLICATION TO BITUMINOUS CONCRETES

This paper deals with the acoustics of porous media saturated by an incompressible viscous or viscoelastic fluid. By using the homogenization method for periodic structures, we determine the macroscopically equivalent medium. We show that the heterogeneous material displays three types of behaviour: biphasic, elastic, viscoelastic, according to the contrast of the mechanical properties of the constituants. This contrast is measured by the small parameter ε, ratio of the dimension of the pores to the macroscopic wave length. Therefore the macroscopic behaviour depends also on the excitation. The calculations of the effective macroscopic coefficients are performed for a one-dimensional geometry. The results applied to a porous media saturated by an Newtonian fluid show that the type of behaviour changes with the frequency. We treat the case of a saturation by a viscoelastic fluid by considering bituminous concretes. We investigate how this material behaves according to the temperature and the excitation frequency. The applicability of a time-temperature equivalency is studied and a comparison between experimental results and the 1D model is presented. © 1990.