ABSTRACT
This study developed a new constitutive model for capturing nonlinear viscoelastic stress-strain responses of a carbon black-filled styrene-butadiene rubber vulcanizate (SBR-CB) under a wide range of deformations. In the assumed micro-mechanical network structure, the isochoric free energy was decomposed into elastic equilibrium and viscoelastic overstress response. Based on our previous performance evaluations of hyperelastic material models, an eight-chain equilibrium network model was employed. For the nonlinear viscoelastic network, a micro-sphere model proposed by Miehe et al was used. A simple phenomenological form was assumed for the micro stress and strain equation. For the micro-inelastic strain evolution equation based on the Rendek and Lion model, a relaxation time depending on strain amplitude was developed in order to reproduce the stress-strain relationship at strain amplitudes of ≤ 50%. The proposed model could practically reproduce dynamic responses of SBR-CB under a wide range of applied strains and strain rates. In addition, the model was thermodynamically consistent and could be implemented in a commercial FEM software.
