AZ31镁合金板热成形中的屈服和损伤:本构实现与数值分析

为了准确预测各向异性镁合金板的成形质量，将改进的GTN损伤模型与各向异性拉压不对称的CPB06屈服本构耦合，并考虑了屈服面形状随塑性应变累积的变化，得到了考虑本构参数随塑性应变演化的各向异性屈服CPB06-GTN损伤模型。基于该模型，在ABAQUS/Explict中编译得到了相应的VUMAT子程序，采用单个单元进行了单轴拉伸和压缩模拟，并通过与实验一致性对比验证了子程序的正确性。使用子程序不仅能够模拟镁合金的各向异性屈服及其不规则的硬化，同时也能够模拟镁合金的损伤破坏。此外，采用编写的子程序进行了热拉深成形的数值模拟，模拟预测与实验结果对比表明，采用各向异性损伤模型的计算结果能够准确预测镁合金的变形及其损伤破坏，模拟结果与实验数据吻合；采用合适的压边力和成形的温度条件及非等温成形方法能够提高镁合金的成形性。

Anisotropic yield and damage in warm forming of AZ31 magnesium alloy sheet: Implementation of constitutive model and numerical analysis

In order to predict the forming quality of the anisotropic magnesium alloy sheet accurately, a modified GTN damage model that incorporates anisotropic/asymmetric CPB06 yield criterion and yield locus evolution with the accumulated plastic strain, the so-called CPB06-GTN anisotropy yielding model with parametric evolution is developed. The modified CPB06-GTN model is implemented into a VUMAT subroutine for ABAQUS/Explicit, and the subroutine is then tested using a single unit. The results show that the simulation predictions are in good agreement with the experimental results in uniaxial tension and compression. Using the VUMAT subroutine, not only anisotropic yielding and irregular hardening but also damage and fracture of magnesium alloys can be well predicted. In addition, the corresponding VUMAT subroutine is compiled to simulate the warm deep drawing process of magnesium alloy, and the simulation results are compared with the experimental data. The results show that the anisotropic yield CPB06-GTN damage model can well predict the deformation and fracture of the magnesium alloy. The formability of magnesium alloys can be improved by adopting the proper blank holder force and forming temperature as well as non isothermal warm forming method.