| The control moment gyroscope is used as an important inertial navigation instrument for spacecraft. It plays an important role in adjusting the attitude, and maintaining the stability of aircraft. However, it vibrates when it is working, which makes noise and shortens it lifespan. The vibration of control moment gyroscope is mainly caused by the rotor vibration. The vibration of the rotor can be divided into vibration with high frequency and low frequency.The energy mainly concentrates on the rim of the rotor when high frequency vibration happens, making bigger local stress, local plastic deformation and faster fatigue fracture on rotor. So vibration with high frequency is more harmful to rotor in contrast with low frequency vibration. Therefore, it is meaningful to reduce the high frequency vibration of the rotor.Vibration characteristics are premises in designing friction damping structure. The causes of rotor vibration impact rotor vibration characteristics.The causes of vibration of rotor are analyzed and bearing waviness is regard as the main reason for the rotor vibration. Accordingly, a kinematics model about bearing waviness is established. Based on the kinematics model of bearing waviness, rotor vibration characteristics, such as amplitude and frequency characteristics, are discussed.Friction damping principles are the basis to design friction damping structure. The distributions of friction damping structure affect vibration reduction. Friction damping structures should locate at resting zones of the rotor according to friction damping principles. Finite-element analysis is done to get the distributed regularity of resting zones. Friction damping structures are designed based on the distribution of resting zones.Based on friction damping structure, factors which affect the vibration reduction are analyzed. The depth of the friction blocks, the magnitude of the friction damping structure interference and load frequency are regarded as the research objects. By secondary development of ANSYS and using the APDL, the friction work generating by friction damping structure is obtained. By comparing the loss ratio of friction work, how do these factors affect the vibration reduction are analyzed.Moreover, three kinds of structure(without friction damping structure, friction damping structure with magnitude of interference 60μm, and 120μm) are tested. Fast Fourier transform is applied to process data. The results show that the vibration reduction structure can successfully reduce the rotor vibration in high frequency and the structure with the interference 120μm works better than the structure with interference 60μm. |
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