Code_Aster
®
Version
5.0
Titrate:
SDLX03 Assembly of braced thin rectangular plates
Date:
23/01/00
Author (S):
B. QUINNEZ
Key
:
V2.05.003-D
Page:
1/8
Manual of Validation
V2.05 booklet: Linear dynamics of the assembled structures
HI-75/01/010/A
Organization (S):
EDF/IMA/MN
Manual of Validation
V2.05 booklet: Linear dynamics of the assembled structures
Document: V2.05.003
SDLX03 - Assembly of rectangular plates
thin braced
Summary:
This three-dimensional problem consists in seeking the frequencies of vibration of a mechanical structure
composed of an assembly of plates where one simulated an effect of stiffening. This test of Mechanics of
Structures corresponds to a dynamic analysis of an assembled structure having a linear behavior. It
includes/understands two modelings.
Via this problem, one tests the element of plate DKT as well as the calculation of the frequencies of
vibration by the method of Lanczos with detection of the modes of rigid body.
In the second modeling, one tests in more the connection between hulls (key word
LIAISON_COQUE
order
AFFE_CHAR_MECA
).
The results obtained are in concord with the results given in guide VPCS (average of results
obtained by various computer codes). The six modes of rigid body were indeed detected.
A comparison with experimental results is also satisfactory.
Code_Aster
®
Version
5.0
Titrate:
SDLX03 Assembly of braced thin rectangular plates
Date:
23/01/00
Author (S):
B. QUINNEZ
Key
:
V2.05.003-D
Page:
2/8
Manual of Validation
V2.05 booklet: Linear dynamics of the assembled structures
HI-75/01/010/A
1
Problem of reference
1.1 Geometry
0.05
0.2
0.375
0.05
0.025
0.075
0.005
1/2 cross section
(lengths
in meters)
Thickness of all the plates:
T = 0.005 m
Plates higher and lower:
length has = 0.375 m
dispatcher B = 0.2 m
Vertical plates:
length has = 0.375 m
width B = 0.05 m
1.2
Properties of materials
E = 2.1 10
11
AP
= 0.3
= 7.800. kg/m
3
1.3
Boundary conditions and loadings
Free structure in any point.
1.4 Conditions
initial
Without object for the modal analysis.
Code_Aster
®
Version
5.0
Titrate:
SDLX03 Assembly of braced thin rectangular plates
Date:
23/01/00
Author (S):
B. QUINNEZ
Key
:
V2.05.003-D
Page:
3/8
Manual of Validation
V2.05 booklet: Linear dynamics of the assembled structures
HI-75/01/010/A
2
Reference solution
2.1
Method of calculation used for the reference solution
The reference solution is that given in card SDLX03/89 of guide VPCS.
The reference solution was obtained by experimental study of the frequencies and clean modes
free structure on a model produced with welded sheets.
The structure suspended by flexible connections is put in vibration by a discharger
electrodynamics. The statement of the Eigen frequencies is obtained starting from an accelerometer.
In addition, of the digital simulations, carried out by various computer codes, allowed to establish
“results of reference” for the models finite elements.
2.2
Results of reference
the first 6 nonnull Eigen frequencies.
2.3
Uncertainty on the solution
Lower than 4%.
2.4 References
bibliographical
[1]
Tests carried out by Company METRAVIB (64 Path of Dampings - LP 182 - 69132 Ecully
Cedex - France). Report/ratio METRAVIB R.D.S. n° 1.604.50 (1987).
Code_Aster
®
Version
5.0
Titrate:
SDLX03 Assembly of braced thin rectangular plates
Date:
23/01/00
Author (S):
B. QUINNEZ
Key
:
V2.05.003-D
Page:
4/8
Manual of Validation
V2.05 booklet: Linear dynamics of the assembled structures
HI-75/01/010/A
3 Modeling
With
3.1
Characteristics of modeling
Elements of hull DKT
Z
X
y
419
409
408
109 108
402401
102 101
502
501
491
201
191
509 508
origins of the axes = center of the structure
Cutting:
Plates higher and lower
10 in length
8 in width
==> 160 meshs TRIA3
Vertical plates
10 in length
1 in width
==> 20 meshs TRIA3
Names of the nodes:
Lower plate:
N101,…, N109
N111,…, N119
...........................
N201,…, N209
Higher plate:
N401,…, N409
N411,…, N419
...........................
N501,…, N509
Vertical plates:
N102, N112,…, N202
N402, N412,…, N502
N108, N118,…, N208
N408, N418,…, N508
3.2
Characteristics of the mesh
A number of nodes:
198
A number of meshs and types:
360 TRIA3
3.3 Functionalities
tested
Controls
Keys
AFFE_CARA_ELEM HULL
ALL
[U4.24.01]
AFFE_MATERIAU ALL
[U4.23.02]
“MECHANICAL” AFFE_MODELE
“DKT”
ALL
[U4.22.01]
DEFI_MATERIAU ELAS
[U4.23.01]
MODE_ITER_SIMULT METHOD
“TRI_DIAG”
[U4.52.01]
CALC_FREQ
OPTION
“TAPE”
FREQ
NMAX_FREQ
Code_Aster
®
Version
5.0
Titrate:
SDLX03 Assembly of braced thin rectangular plates
Date:
23/01/00
Author (S):
B. QUINNEZ
Key
:
V2.05.003-D
Page:
5/8
Manual of Validation
V2.05 booklet: Linear dynamics of the assembled structures
HI-75/01/010/A
4
Results of modeling A
4.1 Values
tested
Command of
clean mode
Reference
experimental
Model reference
finite elements *
Aster
% difference/
model elements
finished
7
606.
584. ± 1%
590.0310
1.03
8
760.
826. ± 1.5%
829.4009
0.41
9
865.
855. ± 1.7%
848.1548
0.80
10
944.
911. ± 2%
908.8566
0.23
11
1113.
1113. ± 3.6%
1097.6578
1.38
12
1144.
1136. ± 4%
1164.0088
2.46
* average of 5 computer codes
4.2 Remarks
Calculations carried out by:
MODE_ITER_SIMULT
METHOD: “TRI_DIAG”
OPTION
“TAPE”
LIST_FREQ:
(1., 1200.)
DIM_SOUS_ESPACE:
12
4.3
Contents of the file results
The first 6 nonnull Eigen frequencies (clean vectors and modal parameters).
4.4 Parameters
of execution
Version: 5.02
Machine: SGI Origin 2000
Overall dimension memory:
64 Mo
Time CPU To use: 2.42 seconds
Code_Aster
®
Version
5.0
Titrate:
SDLX03 Assembly of braced thin rectangular plates
Date:
23/01/00
Author (S):
B. QUINNEZ
Key
:
V2.05.003-D
Page:
6/8
Manual of Validation
V2.05 booklet: Linear dynamics of the assembled structures
HI-75/01/010/A
5 Modeling
B
5.1
Characteristics of modeling
One uses elements of plate DKT
P
16
P
8
P
15
P
9
P
7
P
22
P
23
P
14
P
24
P
21
P
6
P
13
P
5
P
4
P
10
P
1
P
2
P
3
P
18
P
12
P
17
P
20
P
19
P
11
Z
y
X
X
X
P
9
P
10
P
11
P
12
P
19
P
18
P
20
P
4
P
1
P
2
0.025
0.15
0.025
front view
2.5 10
- 3
2.5 10
- 3
P
17
Cutting is done in the following way:
There is 1
element between P
1
and P
2
6
elements between P
2
and P
3
1
element between P
3
and P
4
1
element between P
17
and P
20
10 elements according to sides' parallel with y (P
4
P
5
for example)
2 calculations are passed:
·
in the first calculation, one establishes connections of solid body between the lines:
- P
2
P
7
and P
17
P
22
- P
3
P
6
and P
18
P
21
- P
10
P
15
and P
20
P
23
- P
11
P
14
and P
19
P
24
via the key word factor “LIAISON_COQUE” of control AFFE_CHAR_MECA.
·
in the second calculation, one establishes connections of solid body between the nodes in with respect to
above mentioned line couples via the key word factor “LIAISON_SOLIDE” of the control
AFFE_CHAR_MECA.
5.2
Characteristics of the mesh
A number of nodes:
242
A number of elements TRIA3:
360
5.3 Functionalities
tested
Controls
Keys
AFFE_CHAR_MECA
LIAISON_SOLIDE
LIAISON_COQUE
[U4.25.01]
AFFE_CARA_ELEM HULL
²
ALL
[U4.24.01]
AFFE_MATERIAU ALL
[U4.23.02]
“MECHANICAL” AFFE_MODELE
“DKT”
ALL
[U4.22.01]
DEFI_MATERIAU ELAS
[U4.23.01]
MODE_ITER_SIMULT METHOD
“TRI_DIAG”
[U4.52.01]
CALC_FREQ
OPTION
“TAPE”
FREQ
NMAX_FREQ
Code_Aster
®
Version
5.0
Titrate:
SDLX03 Assembly of braced thin rectangular plates
Date:
23/01/00
Author (S):
B. QUINNEZ
Key
:
V2.05.003-D
Page:
7/8
Manual of Validation
V2.05 booklet: Linear dynamics of the assembled structures
HI-75/01/010/A
6
Results of modeling B
The results of 2 calculations (one with LIAISON_COQUE, the other with LIAISON_SOLIDE) are
identical. One will mention only calculation with LIAISON_COQUE.
6.1 Values
tested
Command of
clean mode
Reference
experimental
Model reference
finite elements *
Aster
% difference/
model elements
finished
7
606.
584. ± 1%
610.2
4.5
8
760.
826. ± 1.5%
852.4
3.2
9
865.
855. ± 1.7%
864.8
1.1
10
944.
911. ± 2%
923.9
1.4
11
1113.
1113. ± 3.6%
1110.8
0.2
12
1144.
1136. ± 4%
1179.5
3.8
* average of 5 computer codes
6.2 Remarks
Calculations carried out by:
MODE_ITER_SIMULT
METHOD: “TRI_DIAG”
OPTION
“TAPE”
LIST_FREQ:
(1., 1200.)
DIM_SOUS_ESPACE:
12
6.3
Contents of the file results
The first 6 nonnull Eigen frequencies (clean vectors and modal parameters).
6.4 Parameters
of execution
Version: 5.02
Machine: SGI Origin 2000
Overall dimension memory:
28 Mo
Time CPU To use: 8.7 seconds
Code_Aster
®
Version
5.0
Titrate:
SDLX03 Assembly of braced thin rectangular plates
Date:
23/01/00
Author (S):
B. QUINNEZ
Key
:
V2.05.003-D
Page:
8/8
Manual of Validation
V2.05 booklet: Linear dynamics of the assembled structures
HI-75/01/010/A
7
Summary of the results
For the modeling A, the results provided by Code_Aster are in the interval of dispersion of
codes which made it possible to establish the reference solution VPCS.
For modeling B, the two ways of writing the connection between the hulls give the same ones
results.