Exploring Deformation Mechanisms in Hierarchical Metallic Nano-Lattices: Experimental and Computational Study

该基金的研究目标是阐明基本的变形机制，这些机制支配着具有竞争性材料和结构诱导尺寸效应的材料系统的整体力学性能。 结晶固体已经显示出既表现出内在/材料尺寸效应，例如多晶体的晶粒尺寸相关强度，又表现出外在/结构诱导的尺寸效应，例如单晶微米柱和纳米柱的尺寸相关强度。 虽然这两种类型的尺寸效应已被独立研究，宏观结构特征尺寸和微观结构特征尺寸合并的材料系统的机械响应是一个关键的开放问题，原因有两个。 首先，用于制造和测试微米级和特别是纳米级结构的实验技术是复杂的，并且通常需要专门的设施。 其次，大多数计算模型无法描述物理现象，这需要离散的原子描述和现实的（即实验上可访问的）时间和空间分辨率。 该研究项目将结合联合收割机先进的粗粒化原子模拟计算模型和新颖的制造和原位实验方法来合成和测试中空金属纳米桁架，这将深入了解纳米结构材料的变形机制和由此产生的机械性能。如果成功，这一跨学科合作研究的成果将在合成具有高度理想性能的新材料方面具有变革性，其在历史上以限制组合（例如刚度和重量）耦合。 所获得的知识承诺是必不可少的结构材料的发展和改进，它做了一个很好的例子来说明固体中的结构-性能关系的重要性，这将包括在课堂和高中教育。 该项目将通过跨学科研究项目培养具有工程和物理背景的本科生，特别强调从代表性不足的群体和妇女中招收学生。 面向K-12学生的广泛推广活动将提供参与的机会，包括邀请高中生在实验室工作三到六周的暑期项目。 PI将为研究生提供培训和职业发展，在一个令人兴奋的跨学科领域将联合收割机材料现象与理论和实验相结合。 最后，集成和迭代的计算和实验任务将为成功的跨学科研究提供一个很好的例子，以缩小跨学科的知识差距。

The research objective of this grant is to elucidate the fundamental deformation mechanisms that govern the overall mechanical properties of material systems with competing material- and structure-induced size effects. Crystalline solids have been shown to exhibit both intrinsic/material size effects, such as the grain-size dependent strength of polycrystals, as well as extrinsic/structure-induced size effects, such as the size-dependent strength of single-crystalline micro- and nano-pillars. While both types of size effects have been studied independently, the mechanical response of material systems in which macro-structural feature size and characteristic size of the microstructure merge is a key open question for two reasons. First, experimental techniques for fabricating and testing micro- and particularly nano-scale structures are intricate and often require specialized facilities. Second, most computational models fail to describe physical phenomena, which require both a discrete atomistic description and realistic (i.e. experimentally accessible) temporal and spatial resolution. This research project will combine advanced computational models for coarse-graining atomistic simulations with novel fabrication and in situ experimental methods to synthesize and test hollow metallic nano-trusses, which will give insight into the governing deformation mechanisms and the resulting mechanical properties of nano-structural materials.If successful, the outcome of this interdisciplinary collaborative research will be transformative in the synthesis of new materials with highly desirable properties, which have been historically coupled in limiting combinations (e.g. stiffness and weight). The gained knowledge promises to be essential for the development and improvement of structural materials, and it makes a prime example to illustrate the importance of structure-property relations in solids, which will be included in classroom and high school education. This project will train undergraduate students from both engineering and physics backgrounds through interdisciplinary research projects with special emphasis on recruiting students from underrepresented groups and women. Broad outreach activities geared towards K-12 students will offer opportunities to become involved, including a summer program for high school students who are invited to spend three to six weeks working in the labs. The PIs will provide training and career development for graduate students in an exciting interdisciplinary field to combine materials phenomena with theory and experiments. Finally, the integrated and iterative computational and experimental tasks will make a prime example for successful interdisciplinary research to close a knowledge gap across scientific disciplines.