考虑损伤的内变量黏弹-黏塑性本构方程

基于Rice 不可逆内变量热力学框架，在约束构型空间中讨论材料的蠕变损伤问题. 通过给定具体的余能密度函数和内变量演化方程推导出考虑损伤的内变量黏弹-黏塑性本构方程. 通过模型相似材料单轴蠕变加卸载试验对一维情况下的本构方程进行参数辨识和模型验证，本构方程能很好地描述黏弹性变形和各蠕变阶段.不同的蠕变阶段具有不同的能量耗散特点. 受应力扰动后，不考虑损伤的材料系统能自发趋于热力学平衡态或稳定态. 在考虑损伤的整个蠕变过程中，材料系统先趋于平衡态再背离平衡态发展. 能量耗散率可作为材料系统热力学状态偏离平衡态的测度；能量耗散率的时间导数可用于表征系统的演化趋势；两者的域内积分值可作为结构长期稳定性的评价指标. 

AN INTERNAL STATE VARIABLE VISCOELASTIC-VISCOPLASTIC CONSTITUTIVE EQUATION WITH DAMAGE

Based on Rice internal state variable thermodynamics, the creep damage is discussed in constrained configuration space. An internal state variable viscoelastic-viscoplastic constitutive equation with damage under constant stress and temperature conditions is derived by giving specific complementary energy density function and evolution functions of internal state variables. Parameters identification and model validation are conducted under one dimensional scene through uniaxial creep test of analogue material by load and unload method. The proposed constitutive equation can describe viscoelastic strain and three phases of creep preferably. Different stages accompany with different energy dissipation processes. The material system without damage tends to thermodynamic equilibrium state or steady state after disturbing by stress. During creep damage process, the material system has a tendency that is from closing to equilibrium state or steady state to departing from equilibrium state. The energy dissipation rate can be a measure of distance between current state and equilibrium state of material system; the time derivative of energy dissipation rate can characterize development trend of system, and their integral value in domain can be regarded as indexes to evaluate the long-term stability of structure.