An Alternative Method for Modelling the Degradation of Hyperelastic Materials Within the Framework of Finite-Strain Elastoplasticity

Abstract

In this paper an alternative method for modeling the degradation of hyperelastic materials within the framework of finite-strain elastoplasticity is presented. The material model is based on the first nonlinear continuum theory for finite deformations for elastoplastic media which allows for the development of objective and thermodynamically consistent material models. Therefore the model and its results, when used in numerical analyses, are independent of the model description and the particularities of the mathematical formulation. Moreover, the model allows for the study of the body’s behavior from a thermodynamic aspect as well, using clear physical interpretations of the plastic flow and “normality rules” in all configurations of the body and all stress spaces, as it enables the expression of the rate of change of internal mechanical energy accumulated in the body in terms of internal mechanical power conjugate stress measures and strain rates. As a result, the internal power density of the model can be related directly to the internal power density of the specimen used in the tensile test of the modelled material. In this paper natural rubber behavior is studied using modified Mooney-Rivlin and neo-Hookean material models.