基于包辛格效应的回弹仿真分析

金属材料在一个方向上的应变硬化降低了反方向的屈服强度，材料包辛格效应的存在对车身成形仿真精度产生了重要影响，尤其现今高强钢和铝合金的大量应用，使车身成形件的回弹问题日益突出，车身模具制造对有限元回弹预测的准确性提出更高的要求。为了提高回弹的仿真精度有必要对材料的包辛格效应进行研究，利用一套夹具对DC06和DP600两种材料的薄板进行拉伸压缩试验，获得不同预应变下的位移加载曲线，通过拉伸压缩试验结果与仿真结果的对比分析，得到能反映材料包辛格效应的非线性混合硬化模型材料参数。开展U形件成形试验，并建立试验的仿真模型，计算DC06和DP600薄板的U形件成形回弹量，分析等向强化、混合强化和随动强化本构模型对回弹预测精度的影响，针对回弹仿真结果和试验结果的差别，对影响仿真精度的材料模型因素进行分析。结果表明，DC06和DP600的包辛格效应大小存在差别，考虑包辛格效应有助于回弹仿真精度的提高，但小曲率弯曲成形回弹计算对材料本构模型的敏感性，限制了回弹仿真精度的提高。

Analysis of Springback Simulation Based on Bauschinger Effect

Strain hardening of mental in one direction reduces the yield stress in the opposite direction, the existence of Bauschinger effect plays a unique role on the accuracy of the sheet metal forming simulation. Especially now extensive use of high strength steels and aluminum alloys, makes springback phenomenon an increasingly important issue, tool manufacturing of Auto-body forming put forward higher requirement for the accuracy of the finite element springback prediction. In order to improve the accuracy of springback prediction it is necessary to study the Bauschinger effect of materials. With a device tension-compression tests of DC06 and DP600 are carried out and the displacement-force relationship in different pretension strain are obtained. U-channel forming tests of DC06 and DP600 is carried out, with the simulation models are built, the magnitude of springback are calculated. The influence of different material models, which include the hardening laws of isotropic hardening, isotropic-kinematic hardening and kinematic hardening, on springback prediction is analyzed by comparing the simulation results, the factor of material model which influence the accuracy of springback prediction are also analyzed. The results show that there are differences between DC06 and DP600 on the size of Bauschinger effect, it is helpful to improve the accuracy of springback calculation when considering the Bauschinger effect, while the sensitivity of material constitutive model on the simulation of small curvature bending forming, limited the springback simulation accuracy.