Computational modeling of inelastic large ratcheting strains

A framework for phenomenological hyperelasto-plasticity with initial anisotropy, kinematic hardening as well as anisotropic damage is presented in [Menzel et al., Int. J. Plasticity (2004), in press]. In this contribution, we exploit and extend this framework to include several back-stresses in order to capture the ratcheting response of polycrystalline metals subjected to cyclic stress with non-zero mid-value. The evolution equations for kinematic hardening resemble a linear combination of the multiple-Armstrong-Frederick and the Burlet-Cailletaud models, which are extended to the large strain setting. The capability of the model to capture various phenomenological characteristics, in particular multi-axial ratcheting, is illustrated by numerical examples. Comparisons with uni-axial and bi-axial experimental ratcheting results for carbon steel are given. Finally, the finite element analysis of a simplified railway turnout component subjected to cyclic loading is presented.