- 學位論文
轉子-軸承系統不平衡、軸彎、 盤歪、不對心之旋振效應分析
Whirl Response Analysis for Unbalance, Initial Bow, Disc Skew and Misalignment of Rotor-Bearing System
摘要
本文使用有限元素方法，建立轉子-軸承系統之離散模型，根據複變法分析有限元素模型之非齊次週期性激振之穩態響應，依據模擬結果，探討不平衡、初始軸彎、盤歪、不對中等系統非齊次效應對於轉子旋振反應之影響。並以運動方程式之推導作為模擬分析之理論基礎，使用有限元素商用軟體ANSYS建立轉子-軸承系統之有限元素模型，並給予系統上述之效應，依據分析結果加以討論。 當轉子不平衡與轉子重量之無因次比值越大，對系統所產生的共振幅值也越大；系統若存在初始軸彎效應，若初始軸彎量與跨距之無因次比值越大，對系統所造成的共振振幅也越大。如果初始軸彎的相位與轉盤質量偏心相反時，兩種效應正好相互抵消。當轉盤歪斜所造成得不平衡力矩與跨距乘以轉子重量之無因次比值越大，則使系統的共振振幅變大；如果圓盤傾斜角與不平衡量相位相同時，其合成的效應會增大系統臨界轉速的振幅，然而，如果是反相時，由圓盤之傾斜角所造成之力矩將抵消徑向不平衡力，進而降低系統的振幅。若系統兩軸聯結處有不對中之效應，頻譜特徵是轉速2倍頻譜峰過大，則其2倍頻之第一共振峰值將會明顯比1倍頻之第一共振峰值大之現象。
並列摘要
In this study, the finite element method is ulilized to built up the discrete model of the rotor-bearing system and the response of the system stability due to misalignment, disc skew, initial bow and unbalance are discused. The simulation and analysis is base on the deriving of the system governing equation, the finite element model of the rotor-bearing system is built up with the finite element software ANSYS and the vibration response that induced by the reasons described above are also simulated by ANSYS. Futher discussions are provided by analysis results. When the unbalance of a rigid disc is large, the resonance amplitude of vibration system is also large. If the effect of initial bow is existed in the system, the resonance vibration is large when the distance of initial bow is large. If the phase of the initial bow and the unbalance in the rotor system is opposite , the vibration response will be reduced . If the angle of disc skew is large , the response vibration of system is large. And the phases between the disc skew and the unbalance are same in the rotor systems, the vibration response in critical speed will be increased. Otherwise in the opposite phase, the moment was created by disc skew will counteract the vibration response of the radial unbalance and reduced the amplitude of the system. If the effect of misalignment between two shaft within coupling, the twice rotary frequency will appear and the amplitude of the first critical speed will larger than which in non-misalignment system.