非线性组合硬化条件下镁合金板料变形回弹预测

Springback prediction of magnesium alloy sheet with nonlinear combined hardening

变形回弹作为金属板料成形的主要缺陷之一,如何提高变应变路径条件下的回弹预测精度一直是研究者们面临的难题.本文针对镁合金变形特点,提出了同时考虑同向硬化、动态硬化和屈服圆畸变的本构模型.以0.8 mm厚AZ31B镁合金板料为研究对象,施加不同预拉伸后进行弯曲变形试验,观察了不同预变形对回弹规律的影响.同时结合有限元分析ABAQUS-Explicit(Vumat)和ABAQUS-Implicit(Umat)对板料的变形及回弹过程进行模拟仿真,对比试验与模拟结果,验证动态硬化对于镁合金板料变形回弹的重要影响.

Springback is regarded as one of the main defects that occur in sheet-metal forming processes. Therefore,improving its prediction accuracy,especially under highly nonlinear conditions,is important for researchers. In this paper,constitutive equations that consider the isotropic hardening,kinematic hardening,and distortional hardening are proposed for magnesium alloy sheet. The work hardening and springback behaviors of 0. 8-mm-thick AZ31 B magnesium alloy sheet were investigated and simulated. The AZ31 B specimen was subjected to a bending process after the pre-tension deformation,which aided in the observation of its springback behavior under nonlinear loading paths. Simulations were conducted using ABAQUS-Explicit（ Vumat） and ABAQUS-Implicit（ Umat）.Comparisons between the experimental and numerical results demonstrate the strong influence of the kinematic hardening on the springback prediction of magnesium alloy sheet.