5. C modeling#
5.1. Characteristics of modeling#
The rotor is modelled by quadratic volume elements (“3D_SI” modeling, MECA_HEXS20).
CALC_MODES calculates the modes specific to standstill (ie. without gyroscopic damping) and in rotation, ie. with gyroscopic damping (option MECA_GYRO), but taking into account or not taking into account the softening effect by centrifugal stiffness (option RIGI_ROTA).
5.2. Characteristics of the mesh#
Number of stitches HEXS20 |
112 |
Table 5.2-1
5.3. Results: comparison between Code_Aster and ANSYS calculations#
The table gives the numerical values tested in this test case. These are the natural frequencies of the cylinder in a free-free configuration at standstill and at 3000 rpm.
Identification |
Reference type |
Reference value |
Tolerance |
Mode 1 |
“EXTERNE” |
2562.08 |
|
Mode 2 |
“EXTERNE” |
2562.08 |
|
Mode 3 |
“EXTERNE” |
2962.72 |
|
Mode 4 |
“EXTERNE” |
2962.72 |
|
Mode 5 |
“EXTERNE” |
6231.34 |
|
Mode 6 |
“EXTERNE” |
6231.34 |
|
Mode 7 |
“EXTERNE” |
6313.73 |
|
Mode 8 |
“EXTERNE” |
6420.42 |
|
Mode 9 |
“EXTERNE” |
6420.42 |
|
Mode 10 |
“EXTERNE” |
6658.75 |
|
Mode 11 |
“EXTERNE” |
6658.75 |
|
Mode 12 |
“EXTERNE” |
7040.85 |
|
Mode 13 |
“EXTERNE” |
7040.85 |
|
Mode 14 |
“EXTERNE” |
7159.02 |
|
Table 5.3-1 : Summary of results tested when stopped (elements HEXS20 )
With under-integration, we can actually see that the difference between Code_Aster and ANSYS decreases from 3% to 1.5% at most.
Identification |
Reference type |
Reference value |
Tolerance |
Mode 1 |
“EXTERNE” |
53.26 |
|
Mode 2 |
“EXTERNE” |
100 |
|
Mode 3 |
“EXTERNE” |
2524.2 |
|
Mode 4 |
“EXTERNE” |
2601.5 |
|
Fashion 5 |
“EXTERNE” |
2928.5 |
|
Mode 6 |
“EXTERNE” |
2998.1 |
|
Mode 7 |
“EXTERNE” |
6211.4 |
|
Mode 8 |
“EXTERNE” |
6251.8 |
|
Mode 9 |
“EXTERNE” |
6313 |
|
Mode 10 |
“EXTERNE” |
6388.2 |
|
Table 5.3-2 : Summary of results tested in rotation without centrifugal sweetening
Identification |
Reference type |
Reference value |
Tolerance |
Mode 1 |
“EXTERNE” |
26.63 |
|
Mode 2 |
“EXTERNE” |
26.63 |
|
Mode 3 |
“EXTERNE” |
50 |
|
Mode 4 |
“EXTERNE” |
50 |
|
Mode 5 |
“EXTERNE” |
2523.74 |
|
Mode 6 |
“EXTERNE” |
2600.99 |
|
Fashion 7 |
“EXTERNE” |
2928.09 |
|
Mode 8 |
“EXTERNE” |
2997.72 |
|
Mode 9 |
“EXTERNE” |
6211.33 |
|
Mode 10 |
“EXTERNE” |
6251.73 |
|
Mode 11 |
“EXTERNE” |
6312.84 |
|
Mode 12 |
“EXTERNE” |
6388.03 |
|
Table 5.3-3: Summary of the results tested in rotation with centrifugal softening