CAREER: Understanding Fiber Bundle Failure Mechanics for Ultra-high Reliability Applications

纤维束(平行细丝)是单位重量最坚固的材料。桥梁缆索、肌肉、柔性防弹衣和航空复合材料都是某种形式的纤维束。了解这些捆绑包的故障属性是至关重要的，但也是具有挑战性的。期望失效概率越低(可靠性越高)，就越难准确预测。该学院早期职业发展(Career)奖支持基础研究，以增加我们对导致捆绑失败的机制的理解。它采用了一种新的计算机建模方法，将实验数据与理论相结合。这将深入了解光纤束的行为，从而更好地估计光纤束故障概率。了解故障概率可以更好地做出决策，并潜在地降低光纤束结构(包括电缆和复合材料)的成本。因此，这项研究的结果将有利于美国的经济和社会。该项目还将为大学预科少数民族学生提供研究和推广机会，激励他们上大学并考虑在STEM的未来，扩大代表不足的群体在研究中的参与，并对工程教育产生积极影响。该项目的目标是了解纤维之间的相互作用如何通过变形到断裂来决定纤维束的应力-应变响应，以及导致纤维束失效的关键驱动机制。捆绑失效是由失稳导致倒塌引起的，了解失稳的起因和失效分布的下尾是保证超高可靠性的关键。该项目的新奇之处在于将建模(机械、概率和随机)与基于数据的蒙特卡罗模拟实验相结合，该模拟将根据实验数据进行广泛验证。该模拟将从数值上确定全束应力应变行为。此外，数值预测一般非线性纤维束载荷-应变特性分布的新能力，将使人们更好地理解纤维载荷分担的基本机理。学生的参与是本项目成功的关键，该项目包括仔细的纤维材料测试、理论概念和统计建模。这项研究非常适合将实验、理论和编程融为一体的学生。他们的新知识和能力将通过纳入外展活动和在专业会议上发表而得到巩固。该奖项反映了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。

Fiber bundles (parallel filaments) are some of the strongest materials per unit weight. Bridge cables, muscles, flexible body armor, and aerospace composites are all fiber bundles of some form. Understanding the failure properties of these bundles is crucial but challenging. The lower the desired failure probability (higher reliability), the harder it is to accurately predict. This Faculty Early Career Development (CAREER) award supports fundamental research to increase our understanding of the mechanisms leading to bundle failure. It uses a new computer modeling method to combine experimental data and theory. This will provide insight into how fiber bundles behave, allowing for better estimation of bundle failure probabilities. Knowing the probability of failure allows for better decision making and potentially decreased costs for structures made from fiber bundles, including cables and composites. Therefore, results from this research will benefit the U.S. economy and society. The project will also provide research and outreach opportunities for pre-college minority students, to inspire them to attend college and consider a future in STEM, broadening participation of underrepresented groups in research and positively impacting engineering education.The objectives of this project are to understand how interactions between fibers determine the bundle’s stress-strain response through deformation to fracture, and the key driving mechanics leading to bundle failure. Bundle failure is caused by instability leading to collapse, and understanding the onset of instability and the lower tail of the failure distribution is critical to ensuring ultra-high reliability. The novelty of this project is the combination of modeling (mechanistic, probabilistic, and stochastic) with experiments in a data-based Monte-Carlo simulation, which will be extensively validated against experimental data. This simulation will numerically determine full bundle stress strain behavior. Further, the new ability to numerically predict distributions of bundle load-strain characteristics for generic, non-linear fibers, will result in improved understanding of the fundamental mechanics of fiber load sharing. Student involvement is key to the success of this project, which involves careful fiber material testing, theoretical concepts, and statistical modeling. This research is ideal for students with a blend of tractable experiments, theory and coding. Their new knowledge and abilities will be cemented through inclusion in outreach activities and presenting at professional conferences.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.