CAREER: Innovations in Microscale Plasticity and Failure Mechanics to Enable Microforming Processes, with Bending and Hydroforming as Paradigms

这项学院早期职业发展(Career)补助金旨在加强对直径为1 mm的微管(直径1 mm)的变形和失效的了解，这些微管的厚度很少(10)个颗粒。这类部件在微电子、微流体和生物医学应用中大量存在。它们的力学行为是由有限的穿透厚度的颗粒数量决定的，这使得连续统近似不合适。在这项研究中，304不锈钢和CuZN 30黄铜微管将在内压和轴向载荷下膨胀并失效，使用为此目的而建立的试验机。这些实验结果将有助于在韩国研究伙伴的帮助下，建立微观结构信息的晶体塑性本构模型。实验的有限元模拟将与该材料模型相结合，以捕捉观察到的变形和破坏。随后，将通过实验和分析相结合的方法来研究两种微制造工艺(微管弯曲和液压成形)。为了这个项目的目的，将制造一个微管弯曲装置，而德国科隆的一个现有装置将用于微管液压成形实验。上面建立的数值和本构模型的性能将根据这些实验进行检查，并将根据需要进行改进，以捕捉观察到的故障。如果成功，这项研究将有助于科学理解材料的晶界变形和破坏。它将使微管弯曲和液压成形在创新的微电子、微流体和生物医学产品中得到更广泛的实施，使美国工业受益。该奖项还将为两名研究生提供在德国和韩国进行为期18-24个月的研究的机会，为他们在研究和工业全球化方面做好准备。最后，培训和融合少数群体将产生一支更加多样化、公平和具有国际竞争力的劳动力队伍。

This Faculty Early Career Development (CAREER) grant aims at enhancing the understanding of deformation and failure of microtubes (diameter 1mm) with few (10) grains through the thickness. Such components abound in microelectronic, microfluidic and biomedical applications. Their mechanical behavior is dominated by the limited number of through-thickness grains, which renders the continuum approximation unsuitable. In this research, stainless steel 304 and CuZn 30 brass microtubes will be inflated under internal pressure and axial load and taken to failure, using a testing machine to be created for this purpose. These experimental findings will then help establish a microstructurally-informed, crystal plasticity constitutive model, with the aid of the research partner in South Korea. Finite element simulations of the experiments will be coupled with this material model to capture the deformation and failures observed. Subsequently, two micromanufacturing processes (microtube bending and hydroforming) will be examined using a combination of experiments and analysis. A microtube bending device will be created for the purposes of this project, while an existing apparatus in Cologne, Germany, will be used for the microtube hydroforming experiments. The performance of the numerical and constitutive models established above will be examined in light of these experiments and will be improved as needed, to capture the failures observed. If successful, this research will contribute to the scientific understanding of grain-dominated deformation and failure of materials. It will enable the broader implementation of microtube bending and hydroforming in innovative microelectronic, microfluidic and biomedical products, benefiting the American industry. The award will also provide two graduate students with the opportunity to perform research for a total of 18-24 months in Germany and South Korea, preparing them well for the globalization of research and industry. Lastly, training and integrating minorities will result in a more diverse, fair and internationally competitive workforce.