An improved hyperelasticity relation in modeling viscoelasticity response of natural and high damping rubbers in compression: experiments, parameter identification and numerical verification

The rate-dependent behavior of natural and high damping rubbers is investigated in the compression regime. The experimental results demonstrate the prominence of the rate-dependent high initial stiffness feature in high damping rubber at low stretch level. A modified hyperelastic model is proposed to represent the rate-independent elastic responses including the high initial stiffness feature. A comparative evaluation is carried out to display the better performance of the proposed hyperelastic model than conventional ones over the strain range in representing the equilibrium and the instantaneous responses. The hyperelastic model is incorporated in a finite deformation rate-dependent model structure. A parameter identification scheme is proposed to identify the parameters for the equilibrium and instantaneous responses from the experimental data. The difficulties of direct application of infinitely fast or slow loading rate to such highly viscous materials to obtain these responses and thereby to identify the nonlinear elastic parameters are overcome. The proposed scheme is applied to three types of specimens including natural rubber and high damping rubber. Finally, numerical results obtained from the finite deformation rate-dependent model are compared with the test results to verify the adequacy and robustness of the proposed parameter identification scheme. (C) 2002 Elsevier Science Ltd. All rights reserved.