The aim of this contribution is to improve the behavior and failure prediction accuracy for magnesium alloy sheet forming simulation by using advanced fully coupled Continuum Damage Mechanics (CDM) model. Starting from known fully coupled constitutive equations at large inelastic (plastic or viscoplastic) strains, three aspects are enhanced on the CDM model developed by Saanouni (2012). The first one concerns the accurate description of tension-compression asymmetry in yielding and hardening of magnesium alloys induced by combined slip and twinning deformations. The second concerns introducing the stress state dependence in damage evolution to improve the fracture prediction under various loading paths. The third deals with temperature and strain rate (viscosity) effects for metal forming processes at elevated temperatures. The improved fully coupled constitutive equations were implemented into finite element code ABAQUS/Explicit via user subroutine VUMAT including the specific local integration scheme to compute the state variables at each quadrature point. Various kinds of tensile tests at different temperatures and strain rates are used to determine the material parameters, and the complete identification procedure is given in details. As validation, the improved model is applied to simulate the three-point bending and circular cup deep drawing tests, the predicted results show good agreements with the experimental observations.

此贡献的目的是通过使用高级的完全耦合的连续损伤力学（CDM）模型来提高镁合金板材成形模拟的行为和失效预测准确性。从已知的在大的非弹性（塑性或粘塑性）应变下的全耦合本构方程出发，对Saanouni（2012年）开发的CDM模型进行了三个方面的改进。）。第一个涉及对滑移和孪生变形共同引起的镁合金屈服和硬化中拉伸压缩不对称的精确描述。第二个问题是在损伤演化中引入应力状态依赖性，以改善在各种载荷路径下的裂缝预测。第三部分涉及高温下金属成型过程的温度和应变率（粘度）效应。改进的完全耦合本构方程通过用户子例程VUMAT实施为有限元代码ABAQUS / Explicit，该子例程包括特定的局部积分方案，以计算每个正交点的状态变量。在不同的温度和应变率下进行的各种拉伸试验可用来确定材料参数，并给出了完整的识别程序。作为验证，该改进模型被用于模拟三点弯曲和圆杯深拉试验，预测结果与实验观察结果吻合良好。