4. B modeling#
4.1. Characteristics of modeling#
The shaft is modelled with girder POU_D_T elements regularly distributed at constant circular section with a diameter equal to the diameter of the rotor studied in line with the initial node of the element. In addition, discrete elements of the DIS_TR type are used for modeling the bearings.
4.2. Characteristics of the mesh#
Number and type of elements:
2000 SEG2
2 POI1
Number of knots: 2001
4.3. Tested sizes and results#
The values of the first 12 frequencies when stopped and for rotation speed \(4000\mathrm{tr}/\mathrm{min}\) are shown in the table below:
Frequency Number |
Rotation speed ( \(\mathrm{tr}/\mathrm{mn}\) ) |
Cadyro calculation with a variable-section tree \(F\) ( \(\mathrm{Hz}\) ) |
Tolerance (%) |
1 |
0 |
332.14 |
1.0 |
4000 |
331.51 |
1.0 |
|
2 |
0 |
332.14 |
1.0 |
4000 |
334.10 |
1.0 |
|
3 |
0 |
1193.81 |
1.0 |
4000 |
1196.30 |
1.0 |
|
4 |
0 |
1193.81 |
1.0 |
4000 |
1202.05 |
1.0 |
|
5 |
0 |
1607.19 |
1.0 |
4000 |
1607.19 |
1.0 |
|
6 |
0 |
2291.51 |
1.0 |
4000 |
2304.73 |
2.0 |
|
7 |
0 |
2291.51 |
1.0 |
4000 |
2312.08 |
2.0 |
|
8 |
0 |
2512.22 |
1.0 |
4000 |
2512.22 |
1.0 |
|
9 |
0 |
3160.39 |
1.0 |
4000 |
3160.39 |
1.0 |
|
10 |
0 |
3520.23 |
2.0 |
4000 |
3516.43 |
2.0 |
|
11 |
0 |
3520.23 |
2.0 |
4000 |
3524.02 |
2.0 |
|
12 |
0 |
4724.14 |
2.0 |
4000 |
4724.14 |
2.0 |
Table 4.3-1 : Natural frequencies obtained by QZ