Designing Tough Composite NanoFibers using Brittle Glasses

使用脆性玻璃设计坚韧的复合纳米纤维该奖项支持复合材料的理论和计算研究以及教育，复合材料是两种或两种以上纯物质的混合物。复合材料在日常生活中无处不在，可以在商用客机、电动汽车、消费电子产品和医疗设备/设备中找到。复合材料设计的共同智慧是，最终的复合材料混合物的性能，例如延展性，必须在组成纯物质的值范围内。因此，为了使脆性材料变韧，一般做法是加入延性材料形成复合材料。这项NSF项目的研究目标是寻求一种新的复合材料设计范式，使所得到的复合材料优于任何纯成分物质。也就是说，我们能否只用脆性成分设计出一种坚韧的复合材料？研究小组将对数千种潜在的复合材料设计进行大规模的原子级模拟，并应用最先进的机器学习算法来优化这种复合材料设计。通过这种新的复合材料设计，脆性材料可以潜在地用于承重结构复合材料，而功能材料可以承受更高的应力而不会出现机械故障。教育方面的努力将包括与“新愿景：数学、工程、技术和科学（METS）”高中项目的合作，以及为核心工程本科课程开发使用Wolfram可计算文档格式（CDF）环境的互动学习模块。该奖项支持设计复合材料的理论和计算研究和教育。大多数材料缺乏非常理想的加工硬化机制，因此氧化玻璃和超硬固体通常不能用作结构材料，硅基电子产品不能弯曲或在冲击中存活。主要动机是设计一种通用的增韧方案，通过利用刚度差将脆性材料组合成复合材料，使其加工硬化。为了实现这一目标，研究团队将进行大规模的分子动力学模拟，探索复合纳米纤维的设计空间，这将作为最先进的机器学习算法的训练数据集。该项目设计的复合纳米纤维具有加工硬化能力，可用于合成坚韧的纳米纤维，作为表征、数据存储或纳米制造的可靠探针，以及宏观纤维、织物或支架的构建块。此外，复合纳米纤维的设计策略和增韧机理可以应用于体块复合材料的增韧，为结构材料开辟了新的模式。重要的是，有了新的复合材料设计，脆性材料（低成本的硅酸盐玻璃，以及超硬材料）可以潜在地纳入结构复合材料。使用坚韧的纤维设计，功能材料和设备可以承受局部应变（锂化或热冲击中的体积膨胀）和全局应变（柔性电子设备或意外跌落的使用应变）。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Designing Tough Composite NanoFibers using Brittle GlassesNon-technical SummaryThis award supports theoretical and computational research and education on composite materials, which are mixtures of two or more pure substances. Composites are ubiquitous in everyday life and can be found in commercial airliners, electric cars, consumer electronics and medical equipment/devices. The common wisdom of composite design is that a property, say ductility, of a final composite mixture must be within the range of values taken by the constituent pure substances. Therefore, in order to toughen a brittle material, the general practice is to incorporate a ductile material to form a composite. The research goal of this NSF project is to seek a new composite design paradigm such that the resulting composite can be superior to any of the pure constituent substances. That is, can one design a tough composite using only brittle constituents? The research team will conduct large-scale atomic-level simulation of thousands of potential composite designs and apply state-of-the-art machine-learning algorithms to optimize such composite design. With this new composite design, brittle materials can potentially be used in load-bearing structural composites, while functional materials can sustain higher stresses without mechanical failure. The educational efforts will include outreach in collaboration with the "New Visions: Math, Engineering, Technology & Science (METS)" high-school program and developing interactive learning modules using the Wolfram Computable Document Format (CDF) environment for core engineering undergraduate courses.Technical SummaryThis award supports theoretical and computational research and education on designing composite materials. Most materials lack highly desirable work-hardening mechanisms, so that oxide glasses and superhard solids generally cannot be used as structural materials, and silicon-based electronics cannot bend or survive impacts. The primary motivation is to devise a general toughening scheme to impart work-hardening to brittle materials by combining them into composites by exploiting stiffness disparity. To accomplish this goal, the research team will carry out large-scale molecular-dynamics simulations exploring the design space of the composite nanofibers, which will be used as a training dataset for state-of-the-art machine-learning algorithms. The composite nanofiber designs from this project, capable of work-hardening, can be used to synthesize tough nanofibers as reliable probes for characterization, data-storage or nano-fabrication, as well as building-blocks for macroscopic fibers, fabrics or scaffolds. In addition, the design strategy and toughening mechanisms for composite nanofibers can be applied to toughen bulk composite, which could open-up a new paradigm for structural materials. Importantly, with the new composite designs, brittle materials (low-cost silicate glasses, as well as superhard materials) can potentially be incorporated into structural composites. Using the tough fiber design, functional materials and devices can tolerate both local strains (volume expansion in lithiation or thermal shock) and global strains (service strain in flexible electronics or accidental drops).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.