New numerical stress solutions to calibrate hyper-visco-pseudo-elastic material models effectively

Abstract

This paper presents new numerical stress solutions for predicting the stress response of hyper-visco-pseudo-elastic solids. It is pointed out that they can be used to identify the constitutive constants of filled rubber-like materials subjected to arbitrary strain history. The constitutive constants are found by minimising the difference between the predicted and the measured stress response. The stress solutions are based on a finite time increment approach and are derived for uniaxial and equibiaxial tension/compression as well as pure and simple shear. The stress solutions make it possible to apply any hyperelastic material model and user-defined damage parameter. Furthermore, the material model parameters may be determined for each loading mode separately or any combination of the different loading modes. With the purpose of demonstrating the application of the stress solution-based parameter identification method used, as a first step, uniaxial cyclic tension tests had been performed on a carbon black filled EPDM rubber. Then, the calibration process was presented in details, applied at a strain rate of 0.01 1/s and the effectiveness of the proposed and the frequently used inverse parameter identification method was compared. Finally, the stress solution-based parameter identification was performed by considering measurements made at different strain rate simultaneously.