Frequency-dependent dynamic properties of rubber materials with a random distribution of voids

A self-consistent multiple scattering approach using the T-matrix method with suitable pair-correlation function has been employed to study the frequency-dependent properties of rubber materials containing a random distribution of voids. Numerical results indicate that for a certain range of concentration of voids, the resonance of the voids controls the frequency-dependent effective properties such that the imaginary part of the effective wavenumber becomes greater than the real part. The so-called “superviscous” propagation in which the propagating wave may be damped out over a distance smaller than a wavelength, seems to occur over a bandwidth controlled by the concentration of voids (c). The bandwidth increasing with concentrations in the range 0 < c < 0.10. For c > 0.10, this kind of behavior does not exist for the material system considered.