基于能量的混凝土单轴受压塑性损伤本构模型

基于不可逆热力学理论及连续介质损伤力学理论,考虑材料的塑性变形与损伤变量之间的耦合关系,认为混凝土材料的塑性Helmholtz自由能与弹性Helmholtz自由能间存在某种内变量函数关系,以此重新定义损伤能量释放率的表达式,并给出内变量函数的具体表达式。参考Weibull分布曲线的形状,建立了损伤能量释放率与损伤变量的关系,推导单轴受压混凝土的损伤演化方程。根据混凝土材料单轴受压下的塑性特征,给出材料塑性变形关系的经验公式,从而建立完整的单轴受压混凝土的塑性损伤本构模型。通过与混凝土的单轴受压试验结果进行对比分析,验证所建模型的有效性,结果表明所建模型能较真实地反映混凝土的非线性行为和损伤演化过程。

A plastic-damage uniaxial compression constitutive of concrete

Based on Irreversible Thermodynamic Theory and continuum damage mechanics,accounting the coupling relation of plastic stain and damage,an internal variable function was supposed between the plastic Helmholtz energy and the elastic Helmholtz energy.The expression of plastic Helmholtz energy was confirmed by proposing an expression of the internal function.Accounting the shape of Weibull distribution,the damage evolution equation of uniaxial compression concrete was deduced by establishing the relation of damage variable and damage energy dissipation rate,which was redefined by the new expression of plastic Helmholtz energy.And an empirical expression of plastic strain was given based on the plastic characteristic of the material.Uniaxial compression test results were used for verification of the model,which can reflect well the nonlinear feature and damage evolution of concrete.