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Improved FEA of deep drawing at elevated temperatures of magnesium sheet materials based on a realistic modelling of their formability at process conditions

基于工艺条件下可成形性的真实建模，改进了镁板材高温深拉的有限元分析

基本信息

批准号：
44192561
负责人：
Professor Dr.-Ing. Bernd-Arno Behrens
金额：
--
依托单位：
Institut für Umformtechnik und Umformmaschinen (IFUM)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2007
资助国家：
德国
起止时间：
2006-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/44192561?language=en
关键词：
Improved FEA deep drawing elevated

项目摘要

The objective of the preceeding project was an improved model of temperature-dependent hardening and softening behaviour of a common magnesium sheet material AZ31 for a more accurate FEA of its forming via deep drawing at elevated temperatures. The quality of the improved model was assessed based on a comparison between simulation and experimental results of a deep drawing process on rectangular cups. The use of the determined flow curve, which realistically reproduces both hardening and softening of the material, in the FEA of the process leads to its higher accuracy compared to the FEA of the process with a conventionally extrapolated continuously increasing flow curve. However, numerical prediction of a deformation localisation and subsequent crack formation in the formed part was not possible as the forming path at the critical material point was outside the validity range of the forming limit curve.The objective of the new project is characterisation of formability of the magnesium sheet material AZ31 in a range of stress and strain states wider than that of the forming limit curve. The characterisation is to be carried out with the help of a method for determination of sheet metal formability based on shear-tensile tests on shear-tensile specimens combined with a method for determination of conventional forming limit curves based on stretching tests on waisted sheet blanks at process-relevant temperatures. The obtained data is to be integrated into a thermo-mechanical simulation of deep drawing at elevated temperatures. Thus, the influence of the stress state and temperature on formability of the studied material is to be described. Furthermore, it should be investigated if an improved formability prediction in the process simulation can be achieved with the determined formability description for process-relevant stress states and temperatures. With project results, an improved material modelling for magnesium sheet materials as well as a process limit extension of their processing via forming are expected to be achieved.

该项目的目的是改进普通镁合金板材AZ31的温度相关硬化和软化行为模型，以便更准确地对其在高温下通过深冲压成形进行有限元分析。改进模型的质量进行了评估的基础上的模拟和实验结果的比较拉深过程中的矩形杯。在过程的FEA中使用所确定的流动曲线（其真实地再现材料的硬化和软化）导致其与具有常规外推的连续增加的流动曲线的过程的FEA相比更高的精度。然而，由于关键材料点处的成形路径超出了成形极限曲线的有效范围，因此无法对成形零件中的变形局部化和随后的裂纹形成进行数值预测。新项目的目标是在比成形极限曲线更宽的应力和应变状态范围内表征镁板材AZ31的可成形性。该表征将借助基于剪切拉伸样本的剪切拉伸测试的金属板材可成形性确定方法，结合基于在工艺相关温度下对腰部板坯进行拉伸测试的传统成形极限曲线确定方法来进行。所获得的数据将被整合到一个热机械模拟在高温下的深冲。因此，应力状态和温度对所研究材料的成形性的影响是要描述的。此外，它应该调查，如果一个改进的可成形性预测的过程模拟可以实现与工艺相关的应力状态和温度的确定的可成形性描述。通过项目成果，预计将实现镁板材的改进材料建模以及通过成型加工的工艺极限扩展。