Collaborative Research: Interdisciplinary Investigation of Warm Forming of Magnesium Alloy Sheet

这一合作研究项目的目标是发展必要的基础知识，以设计稳健的镁合金温成形工艺，重点是材料行为和工艺设计。镁合金通过取代常用材料提供了巨大的减轻重量的潜力。阻碍镁合金进一步开发的一个问题是其较差的低温成形性。一个可能的解决方案是热成形，然而，实际和根本问题仍然存在。工艺优化在很大程度上依赖于拥有良好的有限元(FE)建模框架，以确定各种材料和工艺参数如何相互作用并影响变形过程。由于镁板材的力学行为具有明显的各向异性和不对称性，目前还没有现成的有限元建模框架。在这项工作中，将采用以下方法：多晶塑性建模方法将受相对较少的力学试验的实验数据的约束，以有效地表征材料的本构行为；连续介质模型将被开发并实施到有限元程序中，该有限元程序将特别地捕捉机械孪生的影响；最后，有限元建模将被用于在现有设备中设计和实施温成形模具。由于这项工作的跨学科性质，这项研究结合了三个合作机构--弗吉尼亚大学(UVA)、俄亥俄州立大学(OSU)和佛罗里达大学(UF)--的微观结构、微观力学、塑性、工艺优化、有限元模拟和实验成形专业知识。研究生和本科生将受益于这种互动，以及与金属成形研究所(德国汉诺威)和几家工业贡献者(Sekely Industries和Cyril Bath)的互动。了解各向异性材料的热成形将使许多行业受益，因为它有助于使用许多具有优异性能的难以成形的材料。通过在车辆中加入更多的轻质材料，减少有害温室气体的排放，预计将产生环境效益。

The objective of this collaborative research project is to develop the fundamental understanding necessary to design robust warm forming processes for magnesium (Mg ) alloys, with emphasis on material behavior and process design. Magnesium alloys offer great potential to reduce weight by displacing commonly used materials. A problem that prevents greater exploitation of magnesium alloys' light weight and good properties is their poor low-temperature formability. A possible solution is warm forming, however, both practical and fundamental issues remain. Process optimization relies heavily upon having a good finite element (FE) modeling framework in order to determine how various material and process parameters interact and affect the deformation process. Due to the significant anisotropy and asymmetry in the mechanical behavior of magnesium sheet, no readily available FE modeling framework exists. In this work, the following approach will be employed: a polycrystal plasticity modeling approach will be constrained by experimental data from a relatively small number of mechanical tests to efficiently characterize the material's constitutive behavior; a continuum model will be developed and implemented into an FE-code, which captures the effects of mechanical twinning, in particular; finally, FE-modeling will be used to design and implement warm forming tooling in existing equipment. The design strategy will be subject to experimental validation using a stamped part.Due to the interdisciplinary nature of the work, this research combines the microstructure, micromechanics, plasticity, process optimization, finite element simulation, and experimental forming expertise of the three collaborating institutions -- University of Virginia (UVA), Ohio State University (OSU), and University of Florida (UF). Graduate and undergraduate students will benefit from this interaction, as well as the interaction with the Institute of Metal Forming (Hannover, Germany) and several industrial contributors (Sekely Industries and Cyril Bath). Understanding the warm forming of anisotropic materials will benefit numerous industries, by helping to enable the use of numerous hard-to-form materials that have excellent properties in service. Environmental benefits are anticipated through the increased incorporation of lightweight materials into vehicles leading to decreased emissions of harmful greenhouse gases.