Collaborative Research: A Unified Theory of Crack Nucleation and Growth for Materials Subjected to Repetitive Surface Acoustic Waves and Dynamic Impacts

合作研究：重复表面声波和动态冲击下材料裂纹成核和扩展的统一理论

• 批准号: 2132551
• 负责人: John Dolbow
• 金额: $ 41.79万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2132551&HistoricalAwards=false
• 关键词: Collaborative; Research; Unified; Theory; Crack

Surface acoustic waves (SAWs) are prevalent in many naturally occurring destructive phenomena, such as earthquakes and tsunamis. Further, SAWs have long been speculated to contribute to surface damage produced by cavitation on ship propellers, high-speed impact on wind turbine blades, and fragmentation of rocks by jetting streams. In emerging medical applications, such as Nano-Pulse Lithotripsy, SAWs have also been postulated to play a vital role in ensuring the success of noninvasive disintegration of kidney stones in patients. Despite this, the fundamental mechanisms by which SAWs trigger fracture on the surface of materials remain largely unknown. This is not an isolated phenomenon as the nucleation and propagation of cracks regardless of the loading type has been a vexing problem for decades. In this context, this award supports fundamental research to explain how the repeated application of SAWs and other dynamic loadings can give rise to the nucleation of cracks on the surface of brittle materials and affect their subsequent growth. Insights from this project will significantly benefit scientists and engineers seeking to understand and predict a fundamental phenomenon that has remained elusive: the onset of damage in brittle materials in response to mechanical loads at large. The proposed research is interdisciplinary, bringing together engineers and computational scientists to fully explore this class of problems. Importantly, it also includes outreach activities designed to encourage under-represented minority students in STEM fields at the high school and undergraduate levels to pursue research in mechanics of materials. Despite recent theoretical progress in the field of fracture, the current scientific understanding of crack nucleation and its transition to growth in solids remains incomplete and under-explored. This research is focused on the experimental, theoretical, and computational study of crack nucleation and growth in brittle materials in response to repeated, dynamic loadings under a wide range of conditions. Two prototypical systems will be studied: materials that are submerged and subjected to multiple shock loadings that also cause SAWs, and dry materials that are subjected to repeated impact loads. New experiments will be conducted on both glass and Begostone, an engineered material whose elasticity, strength, and toughness properties can be conveniently varied over a substantial range. The experiments will be carried out in conjunction with simulations based on a new continuum theory that will incorporate inertial effects and low-cycle fatigue into a unified model of crack nucleation and growth. The results of these studies will shed light on the fundamental yet long-unresolved question of how low cycle fatigue and inertial loads can degrade the strength and toughness of material systems and ultimately result in their fracture and failure in response to arbitrary mechanical loads.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.

表面声波（锯）在许多天然发生的破坏性现象（例如地震和海啸中）普遍存在。此外，长期以来，人们长期以来一直猜测锯会导致船舶螺旋桨对船舶螺旋桨造成的表面损伤，对风力涡轮机叶片的高速影响以及通过喷射溪流对岩石的碎片化。 在新兴的医疗应用中，例如纳米脉冲岩石纤维状，也假定锯子在确保肾结石在患者中的无创崩解方面起着至关重要的作用。 尽管如此，锯子在材料表面触发裂缝的基本机制仍然很大未知。这不是一个孤立的现象，因为几十年来，裂纹的成核和裂纹的传播一直是一个令人沮丧的问题。在这种情况下，该奖项支持基本研究，以解释锯和其他动态负荷的重复应用如何导致脆性材料表面裂纹的成核并影响其随后的生长。该项目的见解将使寻求理解和预测仍然难以捉摸的基本现象的科学家和工程师有益：脆弱材料中损坏的发作是响应整个机械负载的响应。拟议的研究是跨学科的，将工程师和计算科学家汇总在一起，以充分探索这类问题。 重要的是，它还包括旨在鼓励高中和本科生在STEM领域中代表不足的少数族裔学生的外展活动，以从事材料力学研究。 尽管裂缝领域的最新理论进步，但目前对裂纹成核的科学理解及其向固体生长的过渡仍然不完整且探索不足。 这项研究集中在脆性材料中裂纹成核和生长的实验，理论和计算研究，以响应在广泛的条件下重复的动态负荷。将研究两个典型的系统：被淹没并承受的材料，并受到多种冲击载荷，也会引起锯和干燥的材料，这些材料受到重复的冲击负荷。新实验将在玻璃和贝格斯通（Ghebostone）上进行，这是一种工程材料，其弹性，强度和韧性特性可以方便地在很大的范围内变化。实验将与基于新的连续理论的模拟结合进行，该理论将将惯性效应和低循环疲劳纳入裂纹成核和生长的统一模型中。 The results of these studies will shed light on the fundamental yet long-unresolved question of how low cycle fatigue and inertial loads can degrade the strength and toughness of material systems and ultimately result in their fracture and failure in response to arbitrary mechanical loads.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.