The theory of unified visco-plastic damage constitutive equations has been frequently used to model the thermal flow behavior and damage evolution of various materials. But the anisotropic properties of materials were generally neglected in the previous studies. In this paper, a novel damage correction formula was proposed, which was expressed as a function of loading path and loading direction and used as a multiplier of a continuum damage model. By integrating a set of unified visco-plastic damage constitutive equations, the Yld2004-18p criterion and the damage correction formula, an improved anisotropic damage constitutive model was established. Anisotropic plasticity and anisotropic damage of AA7075 alloy under hot forming conditions can be properly modeled by this model. Material constants included in the three integrated functions were determined respectively based on different experimental data. The calibrated model is capable to accurately predict the forming limit curves of AA7075 alloy for different forming temperatures, strain rates and loading directions. The model was then numerically implemented in hot Nakajima simulations. The simulation results were evaluated comprehensively from the aspects of limit strain point, punch force- displacement curve, major strain field and fracture position. For further verification of the established model, hot forming simulation of a B-pillar was conducted and compared with a real B-pillar of AA7075 alloy fabricated via an industrial hot stamping process. It is concluded the anisotropic damage constitutive model can be numerically applied to accurately predict the plastic deformation and damage-induced fracture of AA7075 alloy under hot forming conditions.

统一粘塑性损伤本构方程理论经常用于模拟各种材料的热流行为和损伤演化。但以往的研究普遍忽略了材料的各向异性。本文提出了一种新的损伤修正公式，该公式表示为加载路径和加载方向的函数，并用作连续损伤模型的乘数。通过整合一套统一的粘塑性损伤本构方程、Yld2004-18p准则和损伤修正公式，建立了改进的各向异性损伤本构模型。AA7075 合金在热成型条件下的各向异性塑性和各向异性损伤可以通过该模型进行适当建模。三个综合函数中包含的材料常数是根据不同的实验数据分别确定的。校准后的模型能够准确预测AA7075合金在不同成形温度、应变速率和加载方向下的成形极限曲线。然后在热的 Nakajima 模拟中以数值方式实现了该模型。从极限应变点、冲头力-位移曲线、主应变场和断裂位置等方面对仿真结果进行综合评价。为了进一步验证所建立的模型，对 B 柱进行了热成型模拟，并与通过工业热冲压工艺制造的 AA7075 合金的真实 B 柱进行了比较。