The results of experimental investigation of the viscoelastic properties of polymeric elastomer composites on the base of the nitryl-butadien rubber are presented. The elastomeres contained about 50% by weight of the technical carbon N 110. The tests on the stress relaxation under tension and compression of the specimens of two types of composites were carried out for different temperatures. The tension and compression tests with monotonic regimes of loading with the constant strain rate were also carried out. The temperature range of the investigation was from 20 to 150 °C. It was shown that the relaxation properties of the composites are essentially nonlinear. The non-monotonic dependence of the relaxation modulus on the temperature was determined. The integral constitutive equations were used for the description of the experimental data. These equations enable us to take into account both the hyperelastic and viscoelastic properties of materials. The suggested equations represent the total stress in the specimen as a sum of two terms: the hyperelastic and the viscoelastic. The representation of the stress by the hyperelastic potential was used to describe the hyperelastic term of the stress. The nonlinear analog of the integral equation of Boltzman-Volterra was used for the description of viscoelastic part of total stress. The method of the identification of the coupled hyperelastic parameters and the vicoelastic characteristics of material was developed. The experiments on confined compression of cylindrical specimens of the elastomers in a rigid yoke with following stress relaxation were carried out. The experimental data was compared with the results of the numerical modeling. Good agreement between the experimental relations and the calculated ones was found.
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