馬達轉子軸承系統之有限元素 模型修改及模態分析

The Modification of Finite Element Model and Modal Analysis for Motor Rotor-Bearing System

朱家均(Chia-Chun Chu)

指導教授 ： 康淵

中原大學/工學院/機械工程研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200572

摘要

中文摘要
本文探討馬達轉子-軸承-框架系統之結構動態特性，提供動態特性之關係設計過程中，其轉子-軸承系統的動態設計考量方法，利用電腦輔助工程技術，以有限元素方法，先將馬達轉子-軸承-框架系統分離各個部位成為子結構，將子結構個別的數學模型加以離散化，最後以各子結構結合面上節點的動態參數一致性及力系平衡，連結離散化子結構成為整體結構的運動方程式。
在建模型、網格分割及數值求解上，本文使用商用軟體ANSYS，根據分析結果，得到自然頻率與軸承剛度及轉速之關係與模態振形，以及馬達框架之等效剛度等，以此針對馬達轉子-軸承-框架系統之設計提供改善的可行性。
對其馬達轉子進行模態測試實驗，探討分析結果的準確性，並將分析的結果與實驗得到的結果作比對，並根據轉子-軸承系統的物理意義，進行有限元素模型修改，使分析值接近實驗值，以獲得正確的建模方式，提高分析的精準度，以提供給設計者可靠的依據。

關鍵詞：轉子-軸承系統、馬達、有限元素法、模態測試、模態分析、等效剛度。

關鍵字

轉子軸承系統 ； 馬達

並列摘要

ABSTRACT

In this thesis, during design processes of finite element model for motor rotor-bearing system, the different design for finite element model of the rotor is described. Researching the rotor-bearing system on the different finite element model, and studying the effects of analysis results of motor rotor-bearing system.
The use of CAE on the analysis of motor rotor-bearing system, During the numeric model processes, the finite element method is used to build the discrete model and analytical theory of the rotor-bearing system. The entire system is divided into several dividable substructures, each of which develops individual systematic mathematic model. Finally, the motion equation of whole structures is combined by the integrity of the dynamic variables and force balances on connections of each substructure.
On numeric solutions, the analysis and calculations are done by the dynamic and static methods from a model built by the commercial finite element software “ANSYS.” In terms of analytical results, such as the relationship and vibration model of natural frequency and the rigidity of the bearing, the feasibility of the design of the above motor rotor-bearing system is recommended.
In order to verify the accuracy of finite element modeling built by ANSYS for the motor rotor-bearing system in this article, during the analyzing, proceeding mode test experiment of motor rotor, and compare the results of both analysis and experiment. The experimental values are the foundation to consider the physical meanings and to suitably modify the modeling in order to decrease the differences between both results, to obtain the correct modeling type, to increase the analysis accuracy, and to provide designers a reliable basis.

Keywords：Rotor-bearing system, Motor, Finite element method, Modal testing, Modal analysis, Equivalent stiffness.

並列關鍵字

Rotor-Bearing System ； Motor

參考文獻

1. Eshleman, R. L., and Eubanks, R. A., “On the Critical Speeds of a Continuous Shaft-Disk System”, ASME Journal of Engineering for Industry, November, pp. 645-652, 1967.

2. Eshleman, R. L., and Eubanks, R. A., “On the Critical Speeds of a Continuous Rotors”, ASME Journal of Engineering for Industry, Vol. 91, pp. 1180-1188, 1969.

3. Lee, C. W., Katz, R., Ulsoy, A. G., and Scott, R. A., “Modal Analysis of a Distributed Parameter Rotating Shaft”, Journal of Sound and Vibration, 122(1), pp. 119-130, 1988.

4. Prohl, M. A., “A General Method for Calculating Critical Speeds of Flexible Rotors”, Journal of Applied Mechanics, Trans ASME, 1945, 12(3):142~148.

5. Myklestad, N. O., “A New Method for Calculating Natural Modes of Uncoupled Bending Vibration of Airplane Wings and Other Types of Beams”, Journal of Aero Sci, 1994, 11:153~162.