旋转悬臂梁结构振动的非线性抑制研究

The rotating cantilever beams are widely used in engineering. The typical application is high speed rotating blade. The flexible large deformation of high speed rotating blade due to the complex flow filed and structural shape will induce catastrophic vibration. Thus the research on vibration suppression of rotating cantilever beams, which will improve the theory of vibration suppression of rotating cantilever beams and can be used in vibration reduction of turbomachinery blades, has important theoretical meaning and engineering value. NES (Nonlinear Energy Sink) is a passive control nonlinear energy absorber which is widely used in vibration suppression of many engineering structures. This project introduces the NES for vibration suppression of rotating cantilever beams. The forced vibration responses of rotating beams, which is excited by periodic loads and impact loads, suppressed by NES will be investigated. Moreover, the self-excited vibration responses of rotating beams due to fluid-structure interaction and fluid-thermal- structure interaction will be suppressed by using NES. The purposes of this project are obtaining the optimal NES parameters for suppressing different rotating cantilever beams, and revealing the principle of energy transform between NES and rotating cantilever beams. Finally, these studies may be used to guide the vibration control and structure design of turbomachinery blades.

旋转悬臂梁广泛应用于各工程技术领域，其中典型的是高速旋转叶片。高速旋转叶片受复杂流场和结构本身的复杂外形影响，引起结构的柔性大变形，导致严重的振动问题。因而开展旋转悬臂梁的振动抑制研究可以完善旋转悬臂梁的振动抑制理论，还可用于旋转叶片的振动减振，具有十分重要的理论意义和工程应用价值。NES (Nonlinear Energy Sink)作为一种被动控制的非线性吸振器，在各类工程结构的振动抑制中得到了广泛的应用。本项目将NES引入到旋转悬臂梁结构的振动抑制中，将分别研究NES抑制旋转悬臂梁的周期激励和冲击载荷激励作用下的受迫振动响应及由流固耦合和流固热耦合作用而引起的颤振响应。以期获得抑制各类旋转悬臂梁结构振动的最优NES参数，揭示NES与旋转悬臂梁结构之间的能量转移机制。所得结果可以为叶轮机械叶片的振动减振及结构设计提供理论支撑与技术指导。

本项目针对旋转悬臂梁的振动开展非线性抑制研究。建立柔性旋转悬臂梁结构与刚性非线性减振器结构耦合的动力学系统。分别研究了等直线性悬臂梁、等直非线性悬臂梁与变截面悬臂梁的受迫振动的非线性抑制技术。发现旋转悬臂梁的固有频率随转速发生变化，而非线性减振器能够随着转速的变化始终与旋转悬臂梁发生共振。而增大非线性减振器的质量、阻尼和非线性刚度，或者将非线性减振器置于悬臂梁自由端都能够提高减振效果。为讨论非线性减振器对自激振动的抑制，研究了非线性减振器对悬索结构在风激励下驰振响应的抑制。加上非线性减振器后，提高了悬索的临界驰振风速，并降低了悬索在所有风速下的极限环幅值。临界驰振风速的增量与非线性减振器的质量、阻尼和安装位置有关。悬索驰振响应抑制的研究对旋转悬臂梁气流激振的非线性抑制技术研究有一定的借鉴意义。本项目的研究为非线性减振器的理论设计奠定了一定的基础，对促进非线性减振器的发展与工业应用具有一定意义。