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

该合作研究项目的目标是发展必要的基础知识，以设计坚固的镁（Mg）合金热成形工艺，重点是材料行为和工艺设计。镁合金取代常用材料，在减轻重量方面具有很大的潜力。镁合金重量轻、性能好，低温成形性差是制约其进一步开发的一个问题。一个可能的解决方案是热成型，然而，实际和基本问题仍然存在。工艺优化在很大程度上依赖于良好的有限元（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。由于镁片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到来自相对较少的力学测试的实验数据的约束，以有效地表征材料的本构行为；将开发一个连续体模型，并将其执行到fe代码中，该代码特别捕捉到机械孪生的影响；最后，有限元建模将用于在现有设备上设计和实现热成形模具。设计策略将使用冲压件进行实验验证。由于这项工作的跨学科性质，本研究结合了弗吉尼亚大学（UVA）、俄亥俄州立大学（OSU）和佛罗里达大学（UF）这三家合作机构的微观结构、微观力学、塑性、工艺优化、有限元模拟和实验成型专业知识。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（汉诺威，德国）和几个工业贡献者（Sekely Industries和Cyril Bath）的互动。了解各向异性材料的热成型将使许多行业受益，因为它有助于使用许多具有优异性能的难成型材料。预计环境效益通过增加轻型材料纳入车辆导致减少有害温室气体的排放。

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.