AZ31B镁合金板材折弯过程中性层偏移规律研究

Study on neutral layer migration during bending process of AZ31B magnesium alloy sheet

摘要:

有效预测和评估板材变形程度对折弯成形工艺和产品精度控制有着现实的指导意义,且中性层偏移是衡量折弯板材拉压区域不均匀变形程度的重要参数。本文依据塑性变形理论中微元体应力平衡条件,基于能够体现镁合金拉压不对称性的Yoon2014屈服准则,得到了AZ31B镁合金板材折弯过程中中性层偏移量计算模型,并辅以有限元模拟和相应实验对中性层偏移模型进行验证。结果表明：所建立模型能够对镁板中性层偏移现象进行可靠预测,镁板在折弯过程中,受拉压不对称性的影响,中性层向拉伸侧偏移；折弯后角度越小,中性层偏移量越大,在折弯角度为90°,压下量为40mm至47mm之间时的中性层偏移程度最明显。

Abstract:

Effective prediction and evaluation of sheet deformation degree has practical guiding significance for bending forming process and product precision control, and neutral layer offset is an important parameter to measure the degree of uneven deformation in the tension and compression area of bending sheet. In this paper, based on the microelement stress balance condition in the plastic deformation theory and the Yoon2014 yield criterion which can reflect the tension and compression asymmetry of magnesium alloy, the neutral layer offset calculation model in the bending process of AZ31B magnesium alloy sheet was obtained, and the neutral layer offset model was verified by finite element simulation and corresponding experiments. The results show that the model can reliably predict the neutral layer migration phenomenon of magnesium plate. During the bending process of magnesium plate, the neutral layer shifts to the tensile side due to the influence of tension and compression asymmetry. The smaller the Angle after bending, the larger the neutral layer offset. The neutral layer offset is the most obvious when the bending Angle is 90° and the pressure is between 40mm and 47mm.