Effective Dynamic Material Parameters and Localized Scattering

摘要

A modification of the classical effective wave vector in randomly inhomogeneous media ksubp * = ksubp + 2pinfsubp(1,0)/ksubp is discussed, which replaces the single particle far field forward scattering amplitude, fsubp(1,0), by an average pair scattering amplitude, fsubp(2,0). The Perkus-Yevick radial distribution function is used to find the average of fsubp(2,0) over radial separations extending to the first nearest neighbor maximum. The results is applied to random distributions of mass loaded polyurethane spheres in syntactic foam and to lead spheres in an epoxy resin matrix and compared with calculations based on the single particle amplitude. In the case of high concentrations of lead inclusions in epoxy, the mode conversion cross section as well as the real and imaginary parts of the effective wave vector are significantly, altered by pair scattering. In the case of mass loaded polyurethane in syntactic foam, on the other hand, the effects are negligible.