CAREER: Fundamentals of Entropy-Driven Mechanics of Flexible Nanostructures

该学院早期职业发展（Career）奖将支持对柔性、片状纳米结构基本力学的研究。这些纳米结构的例子包括低维材料，如二硫化钼、磷二烯、氮化硼和MXenes，以及生物膜。这些纳米结构在纳米传感器、生物医学设备、基因治疗、纳米电子学、能量收集和结构复合材料中都有应用。这些纳米结构的一个特殊方面是，由于储存的热能，它们不断经历随机变形，这影响了它们的机械行为和对外部刺激的反应。然而，事实证明，将这种效应纳入传统的力学模型是相当困难的。该项目将开发耦合统计力学和固体力学模型，以解释柔性纳米结构中的大热波动。由此产生的框架将使下一代多功能纳米结构的机械指导设计成为可能，应用于国防、医疗保健和环境部门。该奖项还将支持下一代跨学科工程师的教育，特别是促进女性和少数族裔的发展，并通过音乐数学课程等创新活动促进K-12学生的STEM教育。由于其低弯曲刚度，热波动是所有柔性纳米结构的普遍特征，影响其宏观力学行为，包括性能，结构稳定性和动力学。在本项目中，板壳的连续介质力学模型将与统计力学的概念相结合，以表征：(1)具有缺陷的波动膜的宏观力学特性；(2)弹性波动膜的不稳定性、缺陷敏感性和屈曲行为；(3)波动膜的动力学和自由振动和强迫振动的特性。由于非线性、非传统边界条件、普遍存在的热波动和材料缺陷，这些研究具有挑战性。所建立的连续统计力学平台可扩展到纳米材料的熵驱动失效机制、纳米材料的力学耦合特性、生物活性物质等其他小尺度问题。该项目由工程理事会土木、机械和制造创新部（CMMI）的材料和结构力学（mom）项目和生物力学和机械生物学（BMMB）项目共同资助。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。

This Faculty Early Career Development (CAREER) award will support research into understanding the fundamental mechanics of flexible, plate-like nanostructures. Examples of these nanostructures include low-dimensional materials, e.g., molybdenum disulphide, phosphorene, boron nitride, and MXenes, and biomembranes. These nanostructures have applications in nanosensors, biomedical devices, gene therapy, nanoelectronics, energy harvesting, and structural composites. One special aspect of these nanostructures is that they constantly experience random deformations due to stored thermal energy, which affects their mechanical behavior and response to external stimuli. It has proven quite difficult, however, to incorporate this effect into conventional mechanical models. This project will develop coupled statistical mechanics and solid mechanics models that will account for large thermal fluctuations in flexible nanostructures. The resultant framework will enable mechanics-guided design of next-generation multifunctional nanostructures for applications in defense, healthcare, and environmental sectors. The award will also support education of next generation interdisciplinary engineers, especially promoting women and minorities, as well as facilitate STEM education for K-12 students through innovative activities, such as a Musical Math Program.Thermal fluctuations are a universal characteristic of all flexible nanostructures due to their low bending stiffness, which impacts their macroscopic mechanical behavior including properties, structural stability, and dynamics. In this project, continuum mechanics models of plates and shells will be integrated with concepts of statistical mechanics to characterize: (1) the macroscopic mechanical properties of a fluctuating membrane with imperfections, (2) the instability, imperfection sensitivity, and buckling behavior of elastic fluctuating membranes, and (3) the dynamics, and properties of free and forced vibrations of fluctuating membranes. These studies are challenging due to nonlinearities, non-traditional boundary conditions, and ubiquitous presence of thermal fluctuations and material imperfections. The developed continuum-statistical mechanics platform would be extendable to other small-scale problems including entropy-driven failure mechanism of nanomaterials, mechanically coupled properties of nanomaterials, and active matters in biology. This project is jointly funded by the Mechanics of Materials and Structures (MoMS) Program and the Biomechanics and Mechanobiology (BMMB) program in the Division of Civil, Mechanical and Manufacturing Innovation (CMMI) in the Directorate for Engineering (ENG).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.