A comparison between the Perzyna viscoplastic model and the consistency viscoplastic model

The elastic-viscoplastic characteristics of the Perzyna model and the Consistency model are considered. Both theories are compared by assessing the evolution of the viscoplastic multiplier, the evolution of the internal variables and the loading/unloading conditions. An explicit expression is derived for the consistency parameter in the Consistency model. Accordingly, it is shown that the Consistency model and the Perzyna model can be treated in a novel, unified algorithmic fashion. Illustrative numerical examples are given to reveal the differences and the similarities between the models, and to elucidate the features of the proposed implicit numerical scheme.