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.

该学院早期职业发展计划（CAREER）拨款将资助研究，阐明螺栓接头完整性的丧失如何影响安全性和可靠性关键机械结构的弹性和失效进展，并应用于车辆、工业设备、生物医学植入物、太空望远镜和游乐场设备，从而促进科学进步，促进国家繁荣和福利，这是美国基础设施中的常见问题，例如，导致灾难性后果。导致人员伤亡、经济损失和环境破坏的车辆碰撞或火车脱轨对于长期运行过程中结构动力学如何影响螺栓接头的松动知之甚少。该项目通过开发预测建模方法来克服这些挑战，该方法可以捕获结构动力学与螺栓接头完整性之间的耦合，从而与结构的使用寿命一致，从而改善老化的健康监测。该项目通过“探索教学”方法，通过基于游戏的学习和虚拟现实激发学生天生的好奇心，促进 STEM 学习并增强多样性。来自行业和国家实验室的建议和推广确保研究活动符合行业需求，并且结果易于获取和有效评估。本研究旨在为预测长期影响奠定基础。组装结构的非线性动力学项它通过结合新的实验和建模技术来部分实现这一目标，将拧紧的螺栓头周围的应变映射到接头动态演变时界面内的潜在接触条件，例如，测试螺栓连接速率的假设。松动与界面上的相对位移无关，然后从实验测量中导出将螺栓张力与接头刚度和阻尼相关的模型以及控制张力演变的微分方程。作为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 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。