ABSTRACT
ABSTRACT: A novel physically based material model is presented that describes the complex stress-strain behavior of filled rubbers under arbitrary deformation histories in a constitutive manner. The polymer response is considered by the extended non-affine tube model. Stress softening is taken into account via the breakdown of highly stressed polymer-filler domains under load and self-homogenization of the medium. Simulations of the stress-strain response are in good agreement with experiments for different deformations modes, deformation speeds and temperatures. The model is extended to continuous damage and viscoelastic effects by relaxing structure-defining parameters in an appropriate way. This is based on relaxation measurements of differently filled EPDM showing logarithmic relaxation, which can be approximated as a slow powerlaw. It is shown, that powerlaw relaxation can be generated by choosing relaxation times in a specific way. The methodology presented is easily transferable to similar models. The resulting model curves closely resemble true rubber behavior in terms of hysteresis, relaxation characteristics and stress softening.
