Code_Aster ®
Version
4.0
Titrate:
SDLD25 Système mass-arises with viscous damping device
Date:
05/01/98
Author (S):
P. GUIHOT
Key:
V2.01.025-B Page:
1/6
Organization (S): EDF/EP/AMV
Handbook of Validation
V2.01 booklet: Linear dynamics of the discrete systems
V2.01.025 document
SDLD25 - Système mass-arises with damping device
viscous proportional (spectral answer)
Summary
This one-way problem consists in carrying out a spectral seismic analysis of a mechanical structure
composed of a whole of mass-springs with viscous damping devices subjected to a seismic stress
provided in the shape of a spectrum of response of pseudo oscillators in acceleration.
Via this problem, one tests modal combination SRSS of operator COMB_SISM_MODAL
[U4.54.04]. In addition, several operators of preprocessing are tested; DEFI_FONCTION and DEFI_NAPPE.
The results obtained are in concord with the results of guide VPCS.
This test is also a test of resorption of POUX. There are no differences between results ASTER and them
results POUX.
Handbook of Validation
V2.01 booklet: Linear dynamics of the discrete systems
HP-52/96/042 - Ind A

Code_Aster ®
Version
4.0
Titrate:
SDLD25 Système mass-arises with viscous damping device
Date:
05/01/98
Author (S):
P. GUIHOT
Key:
V2.01.025-B Page:
2/6
1
Problem of reference
1.1 Geometry
U1
U2
U3
U8
K
K
K
K
With
m
m
m
m
B
X, U
P1
P2
P3
P8
C
C
C
C
Specific masses:
mP = m = m = ...... = m = m
1
P2
P3
P8
Stiffnesses of connection:
kAP1 = kP1P2 = kP2P3 = ...... = kP8B = K
Viscous depreciation:
cAP1 = cP1P2 = cP2P3 = ...... = cP8B = C
1.2
Material properties
Comes out from linear elastic translation
K =
105 NR/m
Specific mass
m =
10 kg
One-way viscous damping
C =
50 NR/(m/s)
1.3
Boundary conditions and loadings
Not A and b: embedded (U = 0)
Spectrum of acceleration to supports Ý
Ý
U (F, has) normalized with 1. ms2
Points A and b: Ý
Ý
U = Ý
Ý
U (F, has)
ms2
25
0.5%
5%
10
1
1
3
13
33
frequency (Hz)
Handbook of Validation
V2.01 booklet: Linear dynamics of the discrete systems
HP-52/96/042 - Ind A

Code_Aster ®
Version
4.0
Titrate:
SDLD25 Système mass-arises with viscous damping device
Date:
05/01/98
Author (S):
P. GUIHOT
Key:
V2.01.025-B Page:
3/6
2
Reference solution
2.1
Method of calculation used for the reference solution
Comparison with other codes.
Guide VPCS: test in preparation.
2.2
Results of reference
Absolute acceleration according to X at the points A, P1, P2, P3, P4.
2.3 References
bibliographical
[1]
Guide VPCS: Second edition to be appeared.
[2]
J. PIRANDA: Note of use of the software of modal analysis MODAN - Version 0.2.
Laboratory of Mécanique Appliquée - Université de Franche County Besancon (1990).
Handbook of Validation
V2.01 booklet: Linear dynamics of the discrete systems
HP-52/96/042 - Ind A

Code_Aster ®
Version
4.0
Titrate:
SDLD25 Système mass-arises with viscous damping device
Date:
05/01/98
Author (S):
P. GUIHOT
Key:
V2.01.025-B Page:
4/6
3 Modeling
With
3.1
Characteristics of modeling
y
With
P
P
B
X
1
2
P3
P4
P5
P6
P7
P8
Characteristics of the elements:
DISCRET:
with nodal masses
M_T_D_N
and matrices of rigidity
K_T_D_L
and matrices of damping
A_T_D_L
Limiting conditions:
in all the nodes
DDL_IMPO:
(TOUT:“YES” DY: 0. , DZ: 0. )
with the nodes ends
(GROUP_NO: AB DX: 0. )
Names of the nodes:
Not A = N1
P1 = N2
Not B = N10
P2 = N3
.............
P8 = N9
3.2
Characteristics of the grid
A number of nodes: 10
A number of meshs and types: 9 SEG2
3.3 Functionalities
tested
Commands
Keys
AFFE_MODELE
TOUT
“MECANIQUE”
“DIS_T'
[U4.22.01]
GROUP_NO
“DIS_T'
AFFE_CARA_ELEM
DISCRET
GROUP_MA
“K_T_D_L'
[U4.24.01]
GROUP_MA
“A_T_D_L'
GROUP_NO
“M_T_D_N'
COMB_SISM_MODAL
[U4.54.04]
Handbook of Validation
V2.01 booklet: Linear dynamics of the discrete systems
HP-52/96/042 - Ind A

Code_Aster ®
Version
4.0
Titrate:
SDLD25 Système mass-arises with viscous damping device
Date:
05/01/98
Author (S):
P. GUIHOT
Key:
V2.01.025-B Page:
5/6
4
Results of modeling A
4.1 Values
tested
Identification
Reference
Aster
% difference
Eigen frequencies
1
5.53
5.527
- 0.04
2
10.89
10.886
- 0.02
3
15.92
15.915
- 0.02
4
20.46
20.460
0.00
5
24.38
24.383
0.01
6
27.57
27.566
- 0.01
7
29.91
29.911
0.00
8
31.35
31.347
- 0.01
Size localization
ACCE_ABSOLU A DX
1.0
1.0
1.0
P1 DX
10.69
10.45
2.24
P2 DX
19.26
19.03
1.19
P3 DX
25.46
25.32
0.55
P4 DX
29.16
28.95
0.73
4.2 Remarks
Mode
1
2
3
4
5
6
7
8
Damping (in %)
0.868
1.710
2.500
3.213
3.830
4.331
4.698
4.924
Spectrum
23.19
19.54
9.033
3.928
2.282
1.601
1.283
1.136
4.3 Parameters
of execution
Version: 3.05.02
Machine: CRAY
System: UNICOS 8.0
Obstruction memory: 8 megawords
Time CPU To use: 5.75 seconds
Handbook of Validation
V2.01 booklet: Linear dynamics of the discrete systems
HP-52/96/042 - Ind A

Code_Aster ®
Version
4.0
Titrate:
SDLD25 Système mass-arises with viscous damping device
Date:
05/01/98
Author (S):
P. GUIHOT
Key:
V2.01.025-B Page:
6/6
5
Summary of the results
One obtains a good agreement between the Aster solution and the reference solution which comes from other codes.
The Aster results are identical to results POUX until the second decimal.
Handbook of Validation
V2.01 booklet: Linear dynamics of the discrete systems
HP-52/96/042 - Ind A