On solving inconsistencies between different types of hardening models

Abstract

This paper presents the results of a numerical study in which different hardening models were compared. More specifically the following three hardening models were considered: isotropic hardening, combined isotropic-kinematic hardening and combined isotropic-kinematic-distortional hardening. Furthermore, all three models were used in combination with the same Hill 1948 yield surface. The isotropic hardening model was used to simulate tensile tests in different directions and a torsion test. It was then tried to reproduce the outcome of these simulations with the more advanced hardenings models. Therefore, the advanced models were calibrated based on one of the tests simulated with the isotropic hardening model. It was expected that different hardening models would predict the same behaviour for monotonous strain paths, but this is not the case for the models considered in this study. This seems to be an inconsistency complicating the calibration of more advanced constitutive models. In this paper it is shown that this inconsistency can be solved by scaling some parameters in the evolution equations of the kinematic and distortional hardening model with a ratio of two equivalent stresses.