A unified viscoplasticity constitutive model for metal materials is developed within the framework of irreversible thermodynamics, and an expression for the Helmholtz free energy function involving the parameters refl...A unified viscoplasticity constitutive model for metal materials is developed within the framework of irreversible thermodynamics, and an expression for the Helmholtz free energy function involving the parameters reflecting kinematic hardening and isotropic hardening is given. At the same time a non-associated flow potential function including the corresponding state variables is also given, from which the flow equation and the evolution equations of the internal state variables are derived. Thus, a general theoretical framework constructing a unified viscoplasticity constitutive model is given. Compared with the typical unified viscoplasticity constitutive models, the presented model evidently satisfies the irreversible thermodynamics laws. Moreover, this method not only provides a new theoretical foundation for further development of the unified viscoplasticity constitutive model, but also gives a new theoretical framework for the stress-strain analysis of more materials.展开更多
文摘以Chaboche随动强化模型为例,在M isses屈服准则及正交流动准则的前提下,推导了叠加型A rm-strong-F rederick(A-F)类随动强化模型塑性应变的数值计算法,联合利用四阶龙格-库塔法与径向返回法实现数值计算中的内部平衡迭代。同时推导了统一切向矩阵以便确定每一平衡迭代后的试算应变。利用AN SY S提供的U PF s将算法嵌入到AN SY S有限元程序,实现了叠加型A-F类随动强化模型塑性应变的数值计算,并利用四边形单元模拟了单轴循环加载时的棘轮应变,计算结果能够很好地与实验值吻合。
基金Supported by the National Natural Science Foundation of China (Grant NO. 90410012)
文摘A unified viscoplasticity constitutive model for metal materials is developed within the framework of irreversible thermodynamics, and an expression for the Helmholtz free energy function involving the parameters reflecting kinematic hardening and isotropic hardening is given. At the same time a non-associated flow potential function including the corresponding state variables is also given, from which the flow equation and the evolution equations of the internal state variables are derived. Thus, a general theoretical framework constructing a unified viscoplasticity constitutive model is given. Compared with the typical unified viscoplasticity constitutive models, the presented model evidently satisfies the irreversible thermodynamics laws. Moreover, this method not only provides a new theoretical foundation for further development of the unified viscoplasticity constitutive model, but also gives a new theoretical framework for the stress-strain analysis of more materials.
