基于Gurson模型的镁合金板材温热冲压成形研究

Thermal stamping formability of magnesium alloy sheet based on the Gurson model

在Gurson损伤模型的基础上,采用有限元数值模拟与温热冲压实验相结合的方法,对镁合金板材温热冲压成形过程中的材料损伤过程进行了预测.考虑了板材的塑性各向异性行为,通过用户自定义材料子程序VUMAT将损伤模型嵌入到有限元软件ABAQUS/Explicit中.采用单轴拉伸试验数据与有限元数值模拟结果进行迭代,确定了Gurson模型所需要的材料参数.使用ABAQUS模拟得到了镁合金板材温热冲压过程中微孔洞的演变及分布规律.通过扫描电子显微镜,对不同温度下的AZ31镁合金板材由孔洞增长和聚合引起的内部损伤演化进行了观察分析.研究结果表明,板材中微孔洞的分布与实验数据相吻合,说明本文所提出的方法可以应用于金属板材温热冲压成形性能预测.

Based on the Gurson damage model, the thermal stamping formability of AZ31 magnesium alloy sheet was predicted by employing finite element simulation and thermal stamping test. Taking the plastic anisotropic behavior of the AZ31 sheet into account, the Gurson damage model was implemented in the commercial finite element software ABAQUS/Explicit by using the user material sub-routine VUMAT. Parameters employed in the Gurson damage model were determined through uniaxial tensile test and numerical itera-tive computation. The evolvement and distribution of micro voids in the AZ31 sheet during thermal stamping were simulated by using ABAQUS. The internal damage evolution due to micro void growth and coalescence developed at different temperatures in the AZ31 sheet was observed by scanning electron microscopy. The predicted micro void distribution agrees well with experimental data. There-fore, this result indicates that the presented approach can be employed to predict the thermal stamping formability of metal sheet.