Time-dependency and kinematic hardening are two important features of metal materials, and the corresponding behaviors are the emphases of numerical modeling for the safety evaluation of engineering structures. The robust models should not only capture the deformation characteristics, but also satisfy the fundamental thermodynamic laws. This paper aims at discussing the thermodynamic consistency of a unified viscoplasticity (UVP) model and a non-unified viscoplasticity (NUV) model that possess many characteristics in common. Within the thermodynamic framework, the analytical form of a dissipation potential function is defined, and thus the constitutive equations are derived with the introduction of Helmohltz energy function. Finally, a series experimental data of a Nickel based supper alloy is employed to verify the utility of the models. Different from the UVP model, the contribution of creep in a dissipation potential is considered in NUV model, which significantly improves the accuracy of modeling results in the creep and stress relaxation.

时间依赖性和运动硬化是金属材料的两个重要特征，而相应的行为是用于工程结构安全性评估的数值建模的重点。鲁棒模型不仅应捕捉变形特征，还应满足基本的热力学定律。本文旨在讨论具有许多共同特征的统一粘塑性（UVP）模型和非统一粘塑性（NUV）模型的热力学一致性。在热力学框架内，定义了耗散势函数的解析形式，因此，通过引入Helmohltz能量函数，导出了本构方程。最后，采用镍基超合金的一系列实验数据来验证模型的实用性。