CAREER: Modeling the Loosening of Bolted Joints due to Nonlinear Dynamics of Structural Assemblies

职业：对结构组件非线性动力学引起的螺栓接头松动进行建模

• 批准号: 2237715
• 负责人: Keegan Moore
• 金额: $ 72.74万
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2028-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2237715&HistoricalAwards=false
• 关键词: CAREER; Modeling; Loosening; Bolted; Joints

This Faculty Early Career Development Program (CAREER) grant will fund research that clarifies how loss of integrity of bolted joints affects the resilience and progression to failure of safety- and reliability-critical mechanical structures, with application to vehicles, industrial equipment, biomedical implants, space telescopes, and playground equipment, thereby promoting the progress of science, and advancing the national prosperity and welfare. Loose bolts and screws are a common problem in US infrastructure. Structural failures often have catastrophic consequences, for example, resulting in vehicle crashes or train derailments that lead to casualties, economic loss, and environmental damage. Little is known about how a structure’s dynamics influences the loosening of bolted joints over long periods of operation. Models calibrated using data from the time of assembly fail to enable optimized preventative maintenance over a structure’s lifetime. This project overcomes these challenges by developing predictive modeling approaches that capture the coupling between structural dynamics and the integrity of bolted joints over timespans consistent with the structure’s service life, leading to improved health monitoring of aging infrastructure, toughened designs against the impacts of extreme weather, and more reliable energy generation from renewable sources. The project advances STEM learning and enhances diversity through a “Teach for Discovery” approach that engages students’ natural curiosity through game-based learning and virtual reality experiences. Advise from, and outreach to, industry and national labs ensures that the research activities are informed by industry needs and that results are accessible and effectively assessed.This research aims to develop the foundations of a modeling and validation framework for predicting the long-term nonlinear dynamics of assembled structures with loosening bolted joints. It achieves this aim partly by combining new experimental and modeling techniques to map the strains around a tightened bolt head to the underlying contact conditions inside the interface as the joint evolves dynamically, for example, to test the hypothesis that the rate of loosening is independent of the relative displacement across the interface. Models relating bolt tension to joint stiffness and damping and differential equations governing the evolution of the tensions are then derived from experimental measurements. Finally, the theory of nonlinear normal modes is expanded to incorporate bolt tension as a dependent variable and used to characterize the influence of internal resonances on the progression of local damage.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.

这项教师早期职业发展计划（职业）赠款将资助研究，以阐明螺栓固定关节的完整性丧失如何影响安全性和关键可靠性机械结构的失败，并将其应用于车辆，工业设备，生物医学的不屑一顾，太空望远镜，太空望远镜和游乐设备，并在其中促进科学和促进科学繁荣的进步，并促进发展的进步。松动的螺栓和螺钉是美国基础设施中的一个常见问题。结构性故障通常会带来灾难性后果，例如，导致伤亡，经济损失和环境破坏的车辆撞车或火车出轨。关于结构的动态如何影响长期操作的螺栓接头损失，知之甚少。从组装时间开始使用数据进行校准的模型无法在结构的寿命上进行优化的预防性维护。该项目通过开发预测建模方法来克服这些挑战，从而捕获结构动力学和螺栓连接的完整性之间的耦合，而螺栓连接的完整性则与该结构的使用寿命一致，从而改善了对衰老基础设施的健康监测，对极端天气的影响强大的设计，对极端天气的影响进行了强化，并从可恢复可恢复的源代源产生了可靠的能源。该项目通过一种“发现教学”方法通过基于游戏的学习和虚拟现实经验来吸引学生的自然好奇心，从而提高STEM学习并增强多样性。从行业和国家实验室提出建议，并从宣传到行业和国家实验室，并确保研究活动得到行业需求的信息，并可以访问并有效评估结果。这项研究旨在开发建模和验证框架的基础，以预测带有松动螺栓接头的组装结构的长期非线性动力学。它通过结合新的实验和建模技术来部分实现这一目标，以将拧紧的螺栓头周围的应变绘制到界面内部的基础接触条件上，例如动态演化，例如，测试松动速率与界面之间的相对位移无关的假设。然后从实验测量中得出了将螺栓张力与关节刚度和阻尼方程式以及控制张力演变的差分方程的模型。最后，非线性正常模式的理论被扩展为将螺栓张力纳入因变量，并用于表征内部共振对局部损害进展的影响。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响审查标准来通过评估来获得的支持。