Modeling A
==============


Characteristics of the mesh
----------------------------

The rotor is meshed in 13 finite shaft elements of type POU_D_T and of the same length and includes 4 discrete elements of type DIS_TR for modeling disks and bearings. It is the same finite element model that was chosen for calculations by ROTORINSA.

Number of knots: 14

Number and type of elements: 13 SEG2

                          5 POI1


.. image:: images/10000000000003B000000256A4DE607BD524DBE8.png
    :width: 6.2429in
    :height: 3.9484in


.. _RefImage_10000000000003B000000256A4DE607BD524DBE8.png:

**Figure 1-b:** Characteristic of the finite element model under ROTORINSA.


Tested sizes and results
------------------------------


Natural frequencies as a function of the speed of rotation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The values of the first 8 bending frequencies for speeds :math:`0\mathrm{tr}/\mathrm{mn}` and :math:`30000\mathrm{tr}/\mathrm{mn}`, for both software programs, are shown in the table below.


+--------------------------+--------------------------------------------------------------+----------------------+-----------------------+---------------------------------------+---------------------------------+
|**Freq number in flexion**|**Rotation speed** **(** :math:`\mathrm{tr}/\mathrm{mn}` **)**|**ROTORINSA**                                 |**Aster_code**                                                           |
+                          +                                                              +----------------------+-----------------------+---------------------------------------+---------------------------------+
|                          |                                                              |:math:`F(\mathrm{Hz})`|**Depreciation factor**|**Tolerance of** :math:`F(\mathrm{Hz})`|**Damping tolerance** **reduced**|
+--------------------------+--------------------------------------------------------------+----------------------+-----------------------+---------------------------------------+---------------------------------+
|1                         |0                                                             |6.06148E+01           |5.03277E-04            |1E-03                                  |1.E-03                           |
+                          +--------------------------------------------------------------+----------------------+-----------------------+---------------------------------------+---------------------------------+
|                          |30000                                                         |5.41119E+01           |2.66235E-04            |1.E-03                                 |1.4E-03                          |
+--------------------------+--------------------------------------------------------------+----------------------+-----------------------+---------------------------------------+---------------------------------+
|2                         |0                                                             |6.30255E+01           |3.98814E-04            |1.E-03                                 |1.E-03                           |
+                          +--------------------------------------------------------------+----------------------+-----------------------+---------------------------------------+---------------------------------+
|                          |30000                                                         |6.81221E+01           |6.52538E-04            |1.E-03                                 |6.E-03                           |
+--------------------------+--------------------------------------------------------------+----------------------+-----------------------+---------------------------------------+---------------------------------+
|3                         |0                                                             |1.69496E+02           |3.12313E-03            |1.E-03                                 |2.E-03                           |
+                          +--------------------------------------------------------------+----------------------+-----------------------+---------------------------------------+---------------------------------+
|                          |30000                                                         |1.54652E+02           |3.04410E-03            |3.E-03                                 |17.E-03                          |
+--------------------------+--------------------------------------------------------------+----------------------+-----------------------+---------------------------------------+---------------------------------+
|4                         |0                                                             |1.85563E+02           |2.85327E-03            |1.E-03                                 |2.E-03                           |
+                          +--------------------------------------------------------------+----------------------+-----------------------+---------------------------------------+---------------------------------+
|                          |30000                                                         |1.96002E+02           |2.76113E-03            |2.E-03                                 |20.E-03                          |
+--------------------------+--------------------------------------------------------------+----------------------+-----------------------+---------------------------------------+---------------------------------+


The frequencies obtained are in perfect harmony with those of ROTORINSA.

In Code_Aster, we also observe frequencies and modes of torsion and modes of traction/compression. These modes are not calculated by ROTORINSA, as it only models bending behavior. The values of these frequencies are tested in NON_REGRESSION.