| This study critically evaluates the performance of a number of constitutive models in predicting ratcheting responses of carbon steel for a set of uniaxial and biaxial loading histories. Two types of modeling schemes, coupled and uncoupled, are evaluated. The coupled models from Prager, Armstrong-Frederick, Chaboche, Ohno-Wang, and Guionnet are examined. The Prager and the Armstrong-Frederick models perform inadequately. The Chaboche and Ohno-Wang models perform well for uniaxial ratcheting responses, but overpredict the biaxial ratcheting. The Guionnet model simulates one set of biaxial ratcheting response well, but fails in others. Performances of several kinematic hardening rules, when used with the uncoupled Dafalias-Popov model are also evaluated. The Armstrong-Frederick rule simulates one set of biaxial response reasonably. The Voyiadjis-Sivakumar, Phillips, Tseng-Lee, Kaneko and Xia-Ellyin rules fail to simulate the biaxial ratcheting responses. The Chaboche rule, with three decomposed terms, performs reasonably for the whole set of responses. The Ohno-Wang rule also performs reasonably, except for one biaxial response. This study indicates a strong influence of the kinematic hardening rule and its parameter determination scheme on multiaxial ratcheting simulations. The coupled models by McDowell, Jiang-Sehitoglu, Voyiadjis-Basuroychowdhury and AbdelKarim-Ohno, where additional multiaxial parameters are included in the hardening rules, are also investigated. None of these models perform consistently for the whole set of experiments. A modified kinematic hardening rule using the idea of Delobelle and his co-workers in the framework of the Chaboche model is proposed. This new rule performs impressively for all of the ratcheting responses considered. Several models for anisotropic deformation of the yield surface are scrutinized. Most of these models use complex and numerically extensive higher order tensors for the yield surface formulations and thus become less attractive for implementation with a cyclic plasticity model. This study demonstrates the methodology and promise in incorporating the equi-plastic-strain surface proposed by Shiratori and his co-workers into the Dafalias-Popov model for general multiaxial ratcheting simulations. |
