Comparative study of stress relaxation phenomenological constitutive modeling of carbon black-reinforced natural rubber-based compounds

Abstract

Viscoelastic properties of rubber materials are due to the combination of the dual response as an elastic solid and a viscous fluid. This behavior yields in time-dependent mechanical properties; thus, phenomena such as stress relaxation, creep, energy dissipation, hysteresis, and strain rate are observed. In this study, three different carbon black-reinforced natural rubber compounds were experimentally evaluated under stress relaxation and several linear phenomenological constitutive models were fitted to evaluate their viscoelastic parameters. It was observed that both the elastic and viscous parameters increase in a non-linear relation as the strain and carbon black content increase, and the viscous parameters were dependent on the configuration of the model. Maxwell and Zener models exhibited fitting values of 76.08 and 95.10%, respectively, while the Wiechert model showed the best fitting values (above 98.40%) and can be adequately used to estimate the relaxation process of carbon black-reinforced natural rubber applications.