A visco-hyperelastic constitutive description of elastomer behaviour at high strain rates

Abstract

A visco-hyperelastic constitutive equation in integral form is proposed to describe the large deformation response of incompressible elastomeric materials at high strain rates. It comprises two components: the first corresponds to hyperelasticity based on a strain energy density function expressed in polynomial form to characterize quasi-static nonlinear response, while the second is an integral form of first and incorporates a relaxation-time function to capture rate sensitivity and strain history dependence. Instead of a constant relaxation-time, a deformation-dependent function is proposed for the relaxation-time. The model is applied to describe the response of SHA60 rubber and Nylon-6. Material samples are subjected to quasi-static and dynamic loading using a universal testing machine and a Split Hopkinson Bar device respectively. Comparison of the proposed equation with experimental results shows a good degree of agreement and demonstrates its potential to describe the dynamic behavior of viscoelastic materials over a range of strain rates.