CAREER: Vibration-Based Active and Passive Damage Identification of Time-Varying Dynamical Systems with Applications to Rotating Structures

该学院早期职业发展(CALEAR)研究计划的目标是开发基于振动的损伤识别策略，该策略严格适用于时变动态系统。结构健康监测是提高许多关键工程系统安全性和可靠性的关键技术。基于监测结构模态特征变化的策略具有吸引力，因为它们具有非破坏性，并且能够从有限的传感器信息中评估全球结构健康状况。目前基于振动的损伤识别方法的发展在很大程度上依赖于经典的特征向量分解，其中假定测量的反应谱与结构的真实固有频率具有时间不变的对应关系。这一关系不成立的一类重要系统是周期时变动力系统。主要的例子是旋转式结构，如涡轮机、轴、螺旋桨、齿轮系和泵。这种更复杂、时变的谱行为对损伤估计提出了重大挑战，必须找到合适的逆关系来将测量的谱变化与结构系统参数的变化联系起来。该项目将开发基于广义时变模态分解框架的新方法，并结合新的Floquite倍增器损伤敏感性范例。这些新的公式将能够直接根据测量的时域或频率响应信息来估计具有固有时变动力学行为的系统中多个同时结构损伤的严重程度和位置。对于安装了力执行器的转子系统，将探索基于Floquet特征向量配置和周期反馈控制的新的、主动增强的损伤估计策略。在多个控制参数下进行损伤识别，将有效地丰富数据集，从而弥补有限的传感器信息，提高空间损伤分辨率，对于提高依赖于关键旋转机械的基础设施、交通运输和航空航天系统的安全性和可靠性具有重要影响。通过为一大类时变动力系统的损伤估计提供新的分析基础，这项研究将推动实时、现场、预测系统早期故障的方法的发展，并允许增加运行安全裕度。此外，研究结果将对涉及时变动态系统的广泛的控制和信号处理应用具有重要意义。该项目还包括一个全面的教育计划，以研究和实验室演示为切入点，激励和激励有前途的学生追求科学事业。高中外展活动将通过田纳西大学的高中工程系统简介(HITES)计划进行，并将对田纳西东部地区的教育产生宝贵的影响。

The aim of this Faculty Early Career Development (CAREER) research program is to develop vibration based damage identification strategies which are rigorously suited for time-varying dynamical systems. Structural health monitoring is a key technology for enhancing safety and reliability in many critical engineering systems. Strategies based on monitoring changes in a structure's modal characteristics are attractive due to their non-destructive nature and ability to assess global structural health from limited sensor information. The current evolution of vibration based damage identification strategies largely depend on classical Eigenvector decomposition, where it is presumed that the measured response spectrum has a time invariant correspondence with the true natural frequencies of the structure. One important class of systems where this relationship does not hold is for periodically time varying dynamical systems. Prime examples are rotordynamic structures, such as turbines, shafts, propellers, gear-trains and pumps. This more complex, time varying, spectral behavior poses a significant challenge for damage estimation where a suitable inverse relation must be found to relate measured spectral changes to changes in structural system parameters. This project will develop new methods based on a generalized time-varying modal decomposition framework coupled with a novel Floquet multiplier damage sensitivity paradigm. These new formulations will enable estimation of the severity and location of multiple simultaneous structural damages in systems with inherently time varying dynamical behavior directly from measured time domain or frequency response information. For rotordynamic systems equipped force actuators, new, actively enhanced, damage estimation strategies based on Floquet Eigenvector assignment and periodic feedback control will be explored. Performing damage identification under multiple control tunings, will effectively enrich the data set and thereby compensate for limited sensor information and allow for increased spatial damage resolution.This research will have an important impact on enhancing the safety and reliability of many infrastructures, transportation and aerospace systems which rely on critical rotating machinery. By providing a new analytical foundation for damage estimation of a large class of time varying dynamical systems, this research will advance the development of real-time, in-situ, methods for prediction of incipit system failures and allow for increased operating safety margins. Additionally, the research results will have significant implications for a wide array of control and signal processing applications where time varying dynamical systems are involved. This project also involves a comprehensive educational plan which utilizes the research and laboratory demonstrations as an entree point to motivate and inspire up-and-coming students to pursue a scientific career. High school outreach activities will be conduced through the High School Introduction to Engineering Systems (HITES) program at the University of Tennessee and will have a valuable influence on education in the greater East Tennessee region.