Passive Nonlinear Automatic Balancing of Flexible Rotordynamic Structures

不平衡振动是几乎所有旋转结构中的一个重要问题，也是工程中的一个重要问题。传统上，抑制不平衡振动的策略分为两类：i)通过附加偏心质量的被动平衡，以及ii)使用调谐质量吸振器或主动轴承驱动来抑制振动。本项目的目的是提出一种基于被动、非线性、自动平衡原理的替代方法。这种方法需要使用一种特殊的平衡装置，称为自动平衡器，它有偏心的质量，绕着转子？S的旋转轴自由旋转。通过转子S横向振动和平衡器质量运动之间的非线性动力学相互作用，实现了自动平衡。在一定的超临界转子转速下，平衡器质量块自然调整位置，以消除转子的S不平衡。自动平衡方法的一个关键优势是它能够自然地适应不平衡的变化，而不需要电源、传感器或控制系统。该项目的总体目标是：a)开发用于预测装有自动平衡装置的柔性轴和叶片盘转子的稳定性和极限环行为的非线性动力学分析；b)探索新的运动学修改的自动平衡器概念以稳定自动平衡器系统中不需要的非同步极限环轨道；c)探索空间分布的自动平衡器的布置和相互作用，以实现柔性转子的多模式自动平衡。这些分析将使用柔性转子/自动平衡器试验台进行实验验证。该项目开发的非线性动力学分析方法将对其他活跃的研究领域产生重要的科学影响，如流固耦合动力学、机床振动和转子-定子相互作用问题。这项研究还将对依赖于关键旋转机械平稳运行的许多民用基础设施、发电、交通和航空航天系统的安全、可靠性和效率产生未来的好处。例如，通过了解叶片盘中的自动平衡行为，这项研究将揭示使用自动平衡器在燃气轮机发动机中实现自动调整叶片损失补偿的新见解和方法，这反过来将提高航空安全。该项目还具有重大的教育使命。通过进行这项研究，参与该项目的研究生将接受强大的分析和实验研究技能的培训，并将在转子动力学、结构振动和非线性动力学领域发展深厚的知识。此外，在田纳西大学的高中外展活动中，该项目中的实验室设置将提供动手演示，这将促进一个切入点，以激励和激励年轻学生追求科学事业。这些努力将对教育下一代劳动力产生广泛影响，并将对东田纳西地区的教育产生积极影响。

Imbalance vibration is a significant concern in virtually all rotating structures and is an important problem in engineering. Strategies for imbalance vibration mitigation traditionally fall into two categories; i) passive balancing via attached eccentric masses, and ii) vibration suppression using tuned-mass absorbers or active bearing actuation. The aim of this project is to advance an alternative approach based on the principle of passive, nonlinear, automatic balancing. This approach requires use of a special class of balancing devices know as Autobalancers which have eccentric masses that freely revolve around the rotor?s axis of rotation. Automatic balancing is achieved through nonlinear dynamic interaction between the rotor?s lateral vibration and the balancer mass motions. At certain supercritical rotor speeds, the balancer masses naturally adjust their positions to cancel the rotor?s imbalance. A key advantage of the automatic balancing approach is its ability to naturally adapt to imbalance changes without requiring power, sensors or a control system. The overall goals of this project are to; a) develop a nonlinear dynamic analysis for predicting stability and limit-cycle behavior in flexible shaft and bladed-disk rotors fitted with autobalancer devices, b) explore novel kinematically modified autobalancer concepts to stabilize unwanted non-synchronous limit-cycle orbits in autobalancer systems, c) and explore placement and interaction of spatially distributed autobalancers to achieve multi-mode automatic balancing of flexible rotors. These analyses will be experimentally validated using a flexible-rotor/autobalancer testrig. The nonlinear dynamic analysis methods developed in this project will have important scientific impacts in other active research areas such as coupled fluid-structure dynamics, machine tool vibrations, and rotor-stator interaction problems. This research will also have future benefits on the safety, reliability and efficiency of many civil infrastructures, power generation, transportation and aerospace systems which depend on smooth operation of critical rotating machinery. For example, by gaining an understanding of automatic balancing behavior in bladed-disks, this research will reveal new insights and approaches into the use of autobalancers to enable self-adjusting blade-loss compensation in gas turbine engines which, in turn, will enhance aviation safety. This project also has a significant educational mission. By performing this research, the graduate student involved in this project will be trained with strong analytical and experimental research skills and will develop deep knowledge in areas of rotordynamics, structural vibrations and nonlinear dynamics. Additionally, during high school outreach activities at the University of Tennessee, the laboratory setups in this project will provide a hands-on demonstration which will facilitate an entrée point to motivate and inspire younger students to pursue a scientific career. These efforts will have broad impacts on teaching the next generation workforce and will have a positive influence on education in the East Tennessee region.