The response of isotropic composites with viscoelastic matrices
  Explicit expressions for the behavior of statistically isotropic composites with viscoelastic matrices and linear elastic inclusions are determined by application of the correspondence principle. The behavior of the matrix is linear in dilatation and governed by the standard linear model in shear. We demonstrate that in some cases explicit expressions for the behavior of composites with more general behaviors of the matrix can be derived. We also show that under certain loading conditions the response of the composite may be non-monotonous. This is the result of the interaction between two phases with different viscoelastic behaviors and may appear for more general materials. 
Gal deBotton and Limor Tevet-Deree