GOALI: Deformation and Cracking Behavior of Oxide Glass under Indentation

非技术描述：防裂玻璃对于广泛的应用至关重要，如个人电子产品、汽车、太阳能电池板、建筑和海底通信电缆。该项目旨在促进关于玻璃在撞击下产生裂纹的基本知识(例如，将带盖子的智能手机掉到实心地板上)。该项目通过将现场实验与大规模计算机模拟中的虚拟力学测试相结合来获得这一知识。综合教育的一个组成部分是为必修的本科课程“计算材料设计”开发计算模块。参与该项目的学生有机会与康宁公司的研究人员在描述玻璃结构和解决工业环境中的实际问题方面进行互动。在实施这一项目时，对研究生和本科生进行玻璃科学和技术前沿领域的培训。目前正在努力通过激发年轻人的好奇心和向女性和少数族裔灌输信心，来激励和鼓励K-12学生将科学和工程作为一条职业道路。技术细节：尽管进行了广泛的研究，但在急剧接触载荷下，控制玻璃裂纹萌生的因素仍然难以捉摸。这一困难主要是因为在复杂和不均匀的应力下进行局部规模(几十微米)的现场调查所涉及的实验复杂性。在本项目中，多种原位光学诊断技术，如拉曼光谱、光学显微镜和布里渊光散射同时用于表征在均匀应力状态(例如，流体静压、单轴压缩或混合状态)下的玻璃的结构和性能的演变，从而为了解玻璃对尖锐接触载荷的响应提供必要的参考数据。微布里渊光谱被用来绘制压痕下的残余致密化和压痕周围的残余应力场，空间分辨率为~1um。这些结果为理解玻璃在压痕下的变形和破裂行为提供了关键的见解，并为拟合多组分玻璃的分子动力学模拟的势能参数和验证计算机模型提供了关键数据。基于这些可靠的势能，在可控参数的分子动力学模拟中进行了三维纳米压痕等虚拟力学试验，以详细了解在压痕作用下导致不同类型裂纹萌生的动态结构变化、变形模式和临界应力状态。模拟的3D纳米压痕测试正在提供实验中的关键缺失信息，这些实验限制了人们对玻璃破裂的理解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL DESCRIPTION: Crack-resistant glass is of paramount importance for a wide range of applications such as personal electronics, automobiles, solar panels, buildings, and submarine communications cables. This project aims to advance fundamental knowledge on crack initiation in glass under impact (e.g., dropping a smart phone with cover glass onto a solid floor). This project gains this knowledge by integrating in-situ experiments with virtual mechanical tests in large-scale computer simulations. An integrated education component is to develop computational modules for a required undergraduate course “Computational Materials Design”. Students involved in the project have opportunities to interact with researchers at Corning Incorporated in characterizing the structure of glasses and solving practical problems in the industrial setting. In carrying out this project, graduate and undergraduate students are trained in frontier areas of glass science and technology. On-going efforts are being made to inspire and encourage K-12 students to pursue science and engineering as a career path, by igniting curiosity in young minds and instilling confidence in women and underrepresented minorities.TECHNICAL DETAILS: Despite extensive studies, what controls crack initiation in glass under sharp contact loading remains elusive. The difficulty arises mainly due to the experimental complexity associated with in-situ investigations at a local scale (tens of microns) under complex and non-uniform stresses. In this project multiple in-situ optical diagnosis techniques such as Raman, optical microscopy and Brillouin light scattering are used simultaneously to characterize the evolution of structure and properties of glass under uniform stress states (e.g., hydrostatic, uniaxial compression or a mixed state) in a diamond anvil cell to provide the reference data necessary for understanding the glass response to sharp contact loading. Micro-Brillouin spectroscopy is used to map the residual densification underneath an indent and the residual stress field around an indentation with a spatial resolution of ~1 um. These results provide key insights in understanding the deformation and cracking behaviors of glass under indentation, and critical data for fitting potential parameters for molecular dynamics simulations of multi-component glasses and for validating computer models. Based on these reliable potentials, virtual mechanical tests such as 3D nanoindentation in molecular dynamics simulations with well-controlled parameters are carried out to provide a detailed understanding of the dynamic structural changes, the deformation modes, and the critical stress states that lead to the initiation of different types of cracks under indentation. Simulated 3D nanoindentation tests are providing the key missing information in experiments that has limited one’s understanding of how glass cracks.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.