OS-V: 1000 Complex Eigenvalue Analysis of Rotor Bearing System
Rotor Bearing system is an excellent example of rotating machines used in mechanical engineering applications.

図 1. 1D Rotor Model

図 2. 3D Representation of Beams
Benchmark Model
The finite element model, as shown in 図 1 is constrained at all the nodes. Only DOF 1 and 4 are allowed on all the nodes. The model is meshed with beam elements of different sections (図 2). Mass is attached at node 5. An isotropic system is assumed.
Material
- Property
- Value
- Young's modulus
- 207.8 GN/m2
- Density
- 7806 kg/m3
- k22 = k33
- = 4.378 x e7 N/m
- k23 = k32
- = 0 N/m
- DMIG
- The stiffness matrix of the bearing is defined directly in the model as multiple column entries using K2GG.
- GENEL
- A file (.inc) which contains the details of bearing stiffness is imported in the model.
The problem has been solved for Complex Eigenvalue Analysis (ASYNC).
Results

図 3. Eigen Mode Contour Plot for Spin Speed of 1.75e5 RPM and 10th Mode

図 4. Campbell Diagram (For Engine Orders 0.5, 1, 2 and 4)
Mode | Speed (RPM) | Normalized Value | |
---|---|---|---|
Nelson McVaugh 1 | OS 2 | ||
1 | 15470 | 15433.38 | 0.998 |
2 | 17159 | 17069.22 | 0.995 |
3 | 46612 | 46975.50 | 1.008 |
4 | 49983 | 50221.98 | 1.005 |
5 | 64752 | 65122.80 | 1.006 |
6 | 96547 | 92419.20 | 0.957 |
Mode | Speed (RPM) | Normalized Value | |
---|---|---|---|
Nelson McVaugh 1 | OS 2 | ||
1 | 4015 | 4002.56 | 0.997 |
2 | 4120.20 | 4102.75 | 0.996 |
3 | 11989.25 | 12063.20 | 1.006 |
4 | 12200 | 12267.90 | 1.006 |
5 | 18184.25 | 18353.40 | 1.009 |
6 | 20162.25 | 20116.80 | 0.998 |
- Nomenclature
- Critical Speed
- The angular speed of a rotor that matches one of its natural frequencies.
- Whirl Ratio
- Ratio of whirl speed to spin speed.
- Campbell Diagram
- The plot of natural frequencies of the system as functions of the spin speeds.
Model Files
必要なモデルファイルのダウンロードについては、モデルファイルへのアクセスを参照してください。
The model file used in this problem includes:
Rotor_Bearing_1.fem