SDLS300 - Air cooler subjected to an excitation ground

Code_Aster

Version

7.3

Titrate:

SDLS300 - Air cooler subjected to an excitation ground

Date

25/10/04

Author (S):

E. BOYERE, G. ROBERT, F. SOULIE

Key

V2.03.300-A

Page:

1/8

Manual of Validation

V2.03 booklet: Linear dynamics of the hulls and plates

HT-66/04/005/A

Organization (S):

EDF-R & D/AMA, SAMTECH

Manual of Validation
V2.03 booklet: Linear dynamics of the hulls and plates
V2.03.300 document

SDLS300 - Air cooler subjected to an excitation
ground

Summary:

The applicability of this test is the seismic analysis. The studied structure is an air cooler subjected to
an excitation ground.
Displacements are calculated along meridian in plan XZ.
The objective is to test axial, tangential and normal displacements for modal recombinations CQC
and SRSS, for elements hull 3D.
Displacements of reference come from results obtained by several computer codes.

One is interested more particularly in calculation of the Eigen frequencies of this system. Values of reference
are obtained on a model of Fourier with the computation software of structures the SAMCEF software.

Code_Aster

Version

7.3

Titrate:

SDLS300 - Air cooler subjected to an excitation ground

Date

25/10/04

Author (S):

E. BOYERE, G. ROBERT, F. SOULIE

Key

V2.03.300-A

Page:

2/8

Manual of Validation

V2.03 booklet: Linear dynamics of the hulls and plates

HT-66/04/005/A

Problem of reference

1.1 Geometry

ruffle

With

The structure is defined by two arcs of hyperbole.

Dimensions:

ruffle = 55.587 m
Rb = 37.515 m
rc = 35.532 m
h1 = 30.16 m
H2 = 107.01 m
ep = 0.305 m

1.2

Properties of materials

E = 2.76E10 AP
= 0.166
= 2244 kg/m

1.3

Boundary conditions and loading

Boundary conditions

Embedding of the air cooler on the level of the ground.

Loading:

The air cooler is subjected to an excitation in direction X on the level of embedding. Calculation
is realized starting from the spectrum of answer of speed [Figure 1.3-a].

Code_Aster

Version

7.3

Titrate:

SDLS300 - Air cooler subjected to an excitation ground

Date

25/10/04

Author (S):

E. BOYERE, G. ROBERT, F. SOULIE

Key

V2.03.300-A

Page:

3/8

Manual of Validation

V2.03 booklet: Linear dynamics of the hulls and plates

HT-66/04/005/A

Appear 1.3-a: Spectrum of answer of speed

Reference solution

2.1

Method of calculation used for the reference solution

The spectral analysis is carried out with code CASTEM 2000.

2.2

Results of reference

· Frequencies calculated with the SAMCEF software.

· Axial, tangential and normal displacements along the wall located in the xOz plan (X and Z

positive) for modal recombinations CQC and SRSS. (Calculated while taking into account
4 modes).

In order to improve the identification of the modes, one evaluates the spectrum with a model of Fourier. This
modeling was carried out with software the SAMCEF software. The spectrum being very dense, the following table
present that the frequencies lower than 4Hz.

Code_Aster

Version

7.3

Titrate:

SDLS300 - Air cooler subjected to an excitation ground

Date

25/10/04

Author (S):

E. BOYERE, G. ROBERT, F. SOULIE

Key

V2.03.300-A

Page:

4/8

Manual of Validation

V2.03 booklet: Linear dynamics of the hulls and plates

HT-66/04/005/A

Harmonic N°

Frequencies

4 1,14
5 1,17
3 1,24
4 1,35
6 1,45
5 1,50
2 1,53
6 1,62
7 1,70
3 1,73
5 1,93
8 1,96
7 2,03
6 2,09
9 2,26
7 2,28
6 2,42
8 2,45
4 2,47
7 2,55

10 2,60

8 2,67
1 2,80
9 2,82

11 2,98

5 3,01
8 3,04
8 3,10
7 3,10
2 3,20

10 3,21

9 3,29
9 3,37

12 3,40

6 3,56

11 3,65

9 3,70

10 3,80

3 3,81
8 3,83

13 3,86

9 3,91

2.3

Uncertainty on the solution

Comparisons between codes.

2.4 References

bibliographical

The case test is inspired by the following reference:

[1]

P.L. GOULD and S.H. ABU SITTA: Dynamic response off structures to wind and earthquake
loading PENTECH NEAR

Code_Aster

Version

7.3

Titrate:

SDLS300 - Air cooler subjected to an excitation ground

Date

25/10/04

Author (S):

E. BOYERE, G. ROBERT, F. SOULIE

Key

V2.03.300-A

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Manual of Validation

V2.03 booklet: Linear dynamics of the hulls and plates

HT-66/04/005/A

3 Modeling

With

3.1

Characteristics of modeling

3.2

Characteristics of the mesh

The mesh consists of 1860 nodes and 1800 elements hull DKT.

3.3

Functionalities tested

Controls

AFFE_MODELE AFFE MODELING

“DKT”

AFFE_CHAR_MECA DDL_IMPO

THICK AFFE_CARA_ELEM

POST_ELEM MASS_INER

MODE_ITER_SIMULT

METHOD
CALC_FREQ

“TRI_DIAG”
OPTION

“TAPE”

NORM_MODE NORMALIZES

“TRAN_ROTA”

Code_Aster

Version

7.3

Titrate:

SDLS300 - Air cooler subjected to an excitation ground

Date

25/10/04

Author (S):

E. BOYERE, G. ROBERT, F. SOULIE

Key

V2.03.300-A

Page:

6/8

Manual of Validation

V2.03 booklet: Linear dynamics of the hulls and plates

HT-66/04/005/A

Results of modeling A

4.1 Values

tested

Eigen frequencies (Hz)

Only the effective frequencies having a mass higher than 0.1% are indicated in the table
below.

Number of the mode

Ref.

(The SAMCEF software)

Code_Aster

Difference between the SAMCEF software and

Code_Aster in %

1 2.80058

2.80065 0.003

2 2.80058

2.80065 0.003

3 5.92549

5.92490 - 0.010

4 5.92549

5.92490 - 0.010

These four modes make it possible to obtain a good representation of the mass in the direction
of excitation since the effective mass according to X amounts to 83.2%

Horizontal displacement X (m):

Altitude CASTEM

2000

Code_Aster

Variation (%)

(m) CQC SRSS CQC SRSS CQC

SRSS

13.3 1.318E-03

1.316E-03

1.538

E-03 1.432

E-03 16.653 8.740

26.8 1.484E-03

1.485E-03

2.853

E-03 2.669

E-03 92.155 79.744

40.3 1.898E-03

1.898E-03

4.456

E-03 4.249

E-03 134.714 123.819

49.4 2.4448E-03

2.442E-03 5.693

E-03 5.495

E-03 132.872 124.948

63.08 3.278E-03 3.275E-03 7.822

E-03 7.657

E-03 138.603 133.751

76.8 4.570E-03

4.568E-03

1.026

E-02 1.014

E-02 124.510 121.860

90.7 5.918E-03

5.918E-03

1.293

E-02 1.283

E-02 118.516 116.802

100 7.023E-03

7.024E-03

1.477

E-02 1.467

E-02 110.294 108.862

109.3 7.677E-03 7.677E-03 1.658

E-02 1.648

E-02 115.998 114.614

127.9 9.053E-03 9.054E-03 1.990

E-02 1.975

E-02 119.818 118.117

Vertical displacement Z (m):

Altitude CASTEM

2000

Code_Aster

Variation (%)

(m) CQC SRSS CQC SRSS CQC

SRSS

13.3 4.534E-04

4.540E-04

8.297

E-04 8.101

E-04 82.955 78.407

26.8 6.832E-04

6.832E-04

1.712

E-03 1.674

E-03 150.528 145.025

40.3 1.091E-03

1.091E-03

2.464

E-03 2.408

E-03 125.872 120.680

49.4 1.510E-03

1.510E-03

2.892

E-03 2.823

E-03 91.521 86.877

63.08 1.794E-03 1.795E-03 3.424

E-03 3.337

E-03 90.769 85.848

76.8 1.944E-03

1.945E-03

3.840

E-03 3.737

E-03 97.437 92.035

90.7 2.024E-03

2.025E-03

4.173

E-03 4.056

E-03 106.143 100.213

100 2.114E-03

2.115E-03

4.372

E-03 4.244

E-03 106.767 100.630

109.3 2.187E-03 2.188E-03 4.564

E-03 4.427

E-03 108.645 102.266

127.9 2.356E-03 2.358E-03 4.959

E-03 4.803

E-03 110.427 103.663

4.2 Remarks

These four modes make it possible to obtain a good representation of the mass in the direction
of excitation since the effective mass according to X amounts to 83.2%.
Calculation is carried out without the taking into account of the neglected modes.

Code_Aster

Version

7.3

Titrate:

SDLS300 - Air cooler subjected to an excitation ground

Date

25/10/04

Author (S):

E. BOYERE, G. ROBERT, F. SOULIE

Key

V2.03.300-A

Page:

7/8

Manual of Validation

V2.03 booklet: Linear dynamics of the hulls and plates

HT-66/04/005/A

Summary of the results

One is interested in two the first hundred modes of the structure: those are located in tape 0 -
7Hz.
One finds well these frequencies with Code_Aster with a maximum change compared to the solution

of reference of 1.7%.

Four modes make it possible to obtain an effective mass cumulated according to X and there of 83.2%. Mass
effective cumulated according to Z is null. These effective weight breakdowns are identical to those obtained
with the SAMCEF software.

For seismic calculation, displacements obtained are far away from the reference solution.
However, one can express some doubts on the validity of these results of reference, being
data the bad representation of the mass: indeed, for this calculation of reference, the mass
effective cumulated in direction X accounts for 43% of the total mass. This is why this part of
calculation was put in comment in the case-test.