准脆性材料的弹塑性各向异性损伤耦合本构模型研究

针对准脆性材料的非线性特征：强度软化和刚度退化、单边效应、侧限强化和拉压软化、不可恢复变形、剪胀及非弹性体胀，在热动力学框架内，建立了准脆性材料的弹塑性与各向异性损伤耦合的本构关系。对准脆性材料的变形机理和损伤诱发的各向异性进行了诠释，并给出了损伤构形和有效构形中各物理量之间的关系。在有效应力空间内，建立了塑性屈服准则、拉压不同的塑性随动强化法则和各向同性强化法则。在损伤构形中，采用应变能释放率，建立了拉压损伤准则、拉压不同的损伤随动强化法则和各向同性强化法则。基于塑性屈服准则和损伤准则，构建了塑性势泛函和损伤势泛函，并由正交性法则，给出了塑性和损伤强化效应内变量的演化规律，同时，联立塑性屈服面和损伤加载面，给出了塑性流动和损伤演化内变量的演化法则。将损伤力学和塑性力学结合起来，建立了应变驱动的应力-应变增量本构关系，给出了本构数值积分的要点。以单轴加载-卸载往复试验识别和校准了本构材料常数，并对单轴单调试验、单轴加载-卸载往复试验、二轴受压、二轴拉压试验和三轴受压试验进行了预测，并与试验结果作了比较，结果表明，所建本构模型对准脆性材料的非线性材料性能有良好的预测能力。

RESEARCH ON THE COUPLED ANISOTROPIC DAMAGE AND PLASTICITY CONSTITUTIVE MODEL FOR QUASI-BRITTLE MATERIALS

In this paper,non-linear properties of quasi-brittle materials are considered,and a coupled anisotropic damage and plasticity constitutive model for the quasi-brittle materials within the framework of the thermal-dynamics is proposed.The deformation mechanisms of brittle materials and damage-induced anisotropy are interpreted;meanwhile,the relations among various physical quantities based on the damage configuration and effective configuration are offered.The plastic yield criterion and different kinematic hardening rule and isotropic hardening law for the tension and compression are studied in the effective stress space.Within the damage configuration,by adopting the strain energy release rate,the tension and compression damage criteria are established,and the different kinematic hardening rule and the isotropic hardening law for the tension and compression damage are studied simultaneously.Based on the plastic yield criterion and damage criterion,the plastic potential functions and the damage potential function were constructed.The evolutions of internal state variables for the strengthening plasticity and damage are derived through the orthogonal flow principle;at the same time,the evolution of the internal state variables,which described the plastic flow and damage evolution,are developed by combining plastic yield surface and damage loading surface.Integrated the damage mechanics and plasticity,the strain-driven stress-strain incremental constitutive relation is established,and the key points of the numerical integration about the constitutive equations are given.The identification and calibration of constitutive material constants are accomplished through uniaxial loading-unloading cyclic loading test.Some simple tests are predicted,showing that the constitutive model has good predictive ability for nonlinear material properties of quasi-brittle materials.