An improved constitutive model for the rate-dependent mechanical behaviour of rubbery materials

Abstract

In order to accurately predict the mechanical behaviour of fluororubber and silicone rubber under different strain rates, an improved model based on the existing strain rate-dependent viscoelastic constitutive models is proposed in this article. Firstly, a strain rate-dependent variable-order fractional model is established. Then, the method of combining theory and experiment is adopted to explore the influence of the key parameters on prediction accuracy. Following this, the relaxation time is found to be the key factor affecting the accuracy of the predicted results of the mechanical properties through the analyses. Finally, the model is improved by replacing the relaxation time with the viscoelastic coefficient. The results show that the relative errors of the stress prediction results are within 3% for silicone rubber and reduced by 1.7%–4.5% for fluororubber. These findings can provide theoretical references and support for the analysis of the mechanical properties of the similar types of viscoelastic materials.