基于变弹性模量的Ti-6Al-4V板材五点弯曲回弹预测

Prediction of Five-point Bending Springback of Ti-6Al-4VPlates Based on Variable Elastic Modulus

Ti-6Al-4V钛合金材料在弯曲成形过程中会产生较大的回弹,其弹性模量对回弹影响较大,但以往研究均未考虑材料塑性应变变化过程中弹性模量的变化。以Ti-6Al-4V钛合金为对象,进行了材料的单轴拉伸实验和循环加载-卸载实验,以揭示材料各向异性参数及材料弹性模量随塑性应变变化的规律,在此基础上建立了Ti-6Al-4V钛合金变弹性模量数学模型。基于YLD2000-2D屈服准则及变弹性模量和Mises各向同性两种不同的本构模型,对常温下Ti-6Al-4V钛合金板材的五点弯曲过程进行了数值模拟,为了验证数值模拟结果,进行了常温下Ti-6Al-4V板材的五点弯曲实验,结果显示,前者显著提高了Ti-6Al-4V钛合金弯曲回弹预测精度,预测精度相比后者提高了31.18%。

Larger springback might be produced in the bending processes of the Ti-6Al-4Vtitani-um alloys,and the elastic modulus has a greater impact on the springback,but previous studies did not considered the changes of elastic modulus during the plastic strain changes of the materials.The uniaxial tensile tests and cyclic loading-unloading tests of Ti-6Al-4Vtitanium alloys were carried out to determine the anisotropy parameters and the change rule of elastic modulus with plastic strains herein.Then,a mathematical model of variable elastic modulus of Ti-6Al-4Vtitanium alloys was es-tablished.Based on two different constitutive models of YLD2000-2Dyield criterion with variable elas-tic modulus and Mises isotropy,the five-point bending processes of Ti-6Al-4Vtitanium alloy sheets were numerically simulated at room temperature.In order to verify the results of the numerical simu-lation,the five-point bending experiments of the Ti-6Al-4Vsheets were carried out at room tempera-ture.The results show that the former significantly improves the springback prediction accuracy of Ti-6Al-4Vtitanium alloys,which is an increase of 31.18%compared with the latter.