A phenomenological model for the viscoelastic behaviour of natural rubber

Abstract

Abstract The present work is concerned with the study of the viscoelastic behaviour of natural rubber in relaxation tests. A phenomenological model is presented to predict the exact viscoelastic behaviour of natural rubber in a finite strain regime to enhance the experimental fit accuracy. A rate dependent multiplicative deformation gradient tensor is splitted into elastic and viscous parts during deformation. Viscoelastic behaviour of natural rubber is introduced through Jeffrey rheological model with Horgan and Sacoomandy type energy function. A thermodynamically consistent rate-dependent relaxation time scheme is introduced which results reduced material parameters, complexity level and the computational time. The developed constitutive model is validated with stress relaxation test data that depicts the rate-dependent viscoelastic behaviour of natural rubber.