Analytical investigation of the finite viscoelastic model proposed by Simo: critical review and a suggested modification

Abstract

Rubber components such as engine or suspension bearings are loaded during operation with large deformations and high-frequency loads. In industrial applications, finite element analysis software is therefore needed to simulate and predict the behaviour of these components under different scenarios of loading conditions. The usage of such software requires the user to be aware of certain limitations and shortcomings in the implemented material models. In this paper, the stresses as well as the storage and loss modulus are calculated analytically for an example of cyclic simple shear deformations. The analysed material model was firstly proposed by Simo and is available in Abaqus version 2018 for viscoelastic materials under finite strains. The analytical solution is used to highlight the non-physical response of the model under certain loading conditions. A modification of the modelling approach is then proposed to avoid such limitations. The modified model is implemented in the Abaqus software using a user material subroutine (UMAT). The behaviour of the modified model and the original Abaqus model are compared using an example of tie rod under different loading conditions. It is shown that with the suggested modification, reasonable results are obtained and the non-physical responses are eliminated.