  Elastomers are viscoelastic materials and their properties significantly
depend on the loading rate. The actual stress experienced by these materials is
the sum of equilibrium and dissipative (inelastic) terms. At very low loading
rates we can eliminate the significant influence of time effects and model the
material as hyperelastic. In this paper, the features of the experimental
determination and subsequent mathematical description of equilibrium stresses
are considered. Verification of the proposed equations has been carried out for
a series of experiments - cyclic uniaxial tests of samples of materials on the
basis of the same matrix, but with different filler contents and under
different maximum degrees of deformation.
