Acoustic waves in solids with random cavities, I: Effective macroscopic parameters

Abstract

The propagation of acoustic displacement disturbances in an isotropic porous solid is studied experimentally and theoretically under the assumption that the solid contains a large number of cavities being dispersed randomly with respect to their positions, sizes and shapes. The influence of the cavities on the effective velocities of the propagation of acoustic plane waves is considered in the spherical and ellipsoidal cavities approximation. The validity of the spherical cavities approximation is confirmed experimentally and by digital computer calculations for low frequecies and dilute concentrations of the cavities.