To predict the final shape of the deformed part after springback, the calculation of the internal stress distribution in the sheet metal must be accurate. The Bauschinger effect exists when the element of sheet metal undergoes both loading and reverse loading processes, i.e. cyclical loading. Therefore, the influence of the Bauschinger effect becomes more important when the deformation history of the sheet metal is more complicated. For an accurate prediction of springback, the Bauschinger effect must be considered to obtain an accurate internal stress distribution within the sheet metal after deformation.; Based on the foundation of the isotropic kinematic hardening model, the Mroz multiple surface model, and plane strain assumptions, and experimental observation, a new incremental method and hardening model is proposed in this study. In comparison with methods based purely on isotropic hardening, kinematic hardening, and Mroz multiple surfaces models, this new methodology compares well with the experimental results for aluminum sheet metals undergoing multiple bending processes. This new hardening model is not only a generic method for springback prediction but also a hardening model for sheet metal forming process simulation.; An efficient and low cost multiple bending experiment has been designed and performed to investigate the influence of the Bauschinger effect on springback in sheet metal forming. Three different steel sheet metals (high strength, back hard, and AKDQ) and two types of aluminum (AA6111-T4 and AA6022-T4) were used as experimental materials in this study. Based on the experimental results from this research, it can be seen that the influence of the Bauschinger effect on springback is more significant for aluminum than for steels. Therefore, both the deformation history and the Bauschinger effect must be considered to predict springback of aluminum stamping parts. Through this multiple bending experiment, the material parameters (called CM values here) after reverse yield can be obtained. Then, these parameters can be applied to the new hardening model to get more accurate simulation results than can be obtained using the isotropic hardening model, kinematic hardening model, or Mroz multiple yield surfaces regardless of the tooling geometry and the clearance between die and punch.
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机译：为了预测回弹后变形零件的最终形状，必须精确计算钣金件内部应力的分布。当金属薄板的元素同时经历加载和反向加载过程（即循环加载）时，存在鲍辛格效应。因此，当金属板的变形历史更加复杂时，鲍辛格效应的影响变得更加重要。为了精确地预测回弹，必须考虑包辛格效应，以在变形后在钣金内部获得准确的内部应力分布。在各向同性运动硬化模型，Mroz多表面模型和平面应变假设以及实验观察的基础上，提出了一种新的增量方法和硬化模型。与纯粹基于各向同性硬化，运动硬化和Mroz多表面模型的方法相比，该新方法与铝板材经历多次弯曲过程的实验结果进行了很好的比较。这种新的硬化模型不仅是回弹预测的通用方法，而且还是钣金成形过程仿真的硬化模型。设计并执行了一种高效且低成本的多次弯曲实验，以研究鲍辛格效应对钣金成形中回弹的影响。在本研究中，使用了三种不同的钢板（高强度，高硬度和AKDQ）和两种类型的铝（AA6111-T4和AA6022-T4）作为实验材料。根据这项研究的实验结果，可以看出，鲍辛格效应对回弹的影响对铝比对钢更重要。因此，必须同时考虑变形历史和包辛格效应来预测铝冲压件的回弹。通过多次弯曲实验，可以获得反向屈服后的材料参数（此处称为 CM 值）。然后，这些参数可以应用于新的淬火模型，以获得比使用各向同性淬火模型，运动硬化模型或Mroz多重屈服面获得的更精确的仿真结果，而不管模具的几何形状以及冲模和冲头之间的间隙如何。
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