3. Modeling A#

3.1. 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

_images/10000000000003B000000256A4DE607BD524DBE8.png

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

3.2. Tested sizes and results#

3.2.1. Natural frequencies as a function of the speed of rotation#

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

Freq number in flexion

Rotation speed ( \(\mathrm{tr}/\mathrm{mn}\) )

ROTORINSA

Aster_code

\(F(\mathrm{Hz})\)

Depreciation factor

Tolerance of \(F(\mathrm{Hz})\)

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.