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Code_Aster
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Version
6.4
Titrate:
Note of use of calculations of sensitivity
Date
:
13/05/03
Author (S):
G. NICOLAS
Key
:
U2.08.02-A
Page
:
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U2.08 booklet: Advanced functions and control of calculations
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Organization (S):
EDF-R & D/SINETICS















Instruction manual
U2.08 booklet: Advanced functions and control of calculations
Document: U2.08.02



Note of use of calculations of sensitivity


Summary:

To calculate the sensitivity of a result to a given parameter supposes two interventions:
·
to define a data as being a significant parameter,
·
to activate the effective calculation of the sensitivity.

This document presents the whole of the operations to be made for that. It details each control
concerned. An example illustrates the recommendations progressively.
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Code_Aster
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Version
6.4
Titrate:
Note of use of calculations of sensitivity
Date
:
13/05/03
Author (S):
G. NICOLAS
Key
:
U2.08.02-A
Page
:
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U2.08 booklet: Advanced functions and control of calculations
HI-23/03/002/A
Count
matters
1
Introduction ............................................................................................................................................ 3
2
An example emblematic .................................................................................................................... 4
3
How to set up a calculation of sensitivity ................................................................................ 6
3.1
Essence ........................................................................................................................................ 6
3.2
To define the significant parameters ..................................................................................................... 6
3.3
To use the significant parameters ..................................................................................................... 7
3.4
To launch the derivation of the main field .......................................................................................... 7
3.5
To derive the secondary fields ...................................................................................................... 7
3.6
Post-to treat the results ................................................................................................................... 8
4
Example: calculation, comments and results ......................................................................................... 9
5
General comments ...................................................................................................................... 14
5.1
Automation of the analysis of the controls ............................................................................... 14
5.2
Performance .................................................................................................................................. 14
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Code_Aster
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Version
6.4
Titrate:
Note of use of calculations of sensitivity
Date
:
13/05/03
Author (S):
G. NICOLAS
Key
:
U2.08.02-A
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:
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U2.08 booklet: Advanced functions and control of calculations
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1 Introduction
Whatever the type of problem considered, thermal, mechanical, etc, Code_Aster produces two
types of results: buildings or total. It can be a field distributed on the mesh, like
temperature or stresses, or it can be a total value, like the rate of refund
of energy. But in both cases, we represent ourselves this result like a function of
data. These data are of varied origin. We find as follows:
·
geometry of the field of calculation,
·
mode of discretization through the choice of the mesh,
·
boundary conditions, like the imposed temperatures or displacements,
·
loadings, like the sources of energy or the imposed pressures,
·
material properties,
·
choices of calculation, like the criteria of convergence.
The list is not exhaustive. Obviously, the result is sensitive to each one of these data. But
obviously we do not propose automatic calculation of all the sensitivities. It is even of
many cases where a quantified evaluation does not have a direction. Such as for example quantifying the sensitivity to
choice of the method of resolution of the matric system related to calculation? Calculations of sensitivity
available with Code_Aster are restricted with the cases where the data is a real parameter, clearly
identified in the data file, and where we know to derive the function which binds this data to the result.
Let us take some examples:
·
choice of the mesh: not, because it is not a real parameter,
·
value of displacement or imposed pressure: yes,
·
numbers of pitches of time: not, because it is an entirety,
·
property of materials: yes and not; yes if the significant value is a pure Young modulus,
not if one is interested in a property given by a curve point by point,
·
criterion of convergence: not, because we do not know to derive the result,
·
etc
We will detail the possibilities for each type of problem. It is enough to keep present at the spirit
regulate stated higher: Code_Aster treats only the cases where the result is in the form
)
(p
U
, where
p
is a visible real parameter and where the partial derivative
p
U
exist. Then Code_Aster will produce this
derivative partial, of comparable nature total or local that the result, this derivative being calculated with
not nominal of operation.
The physical direction attached to the value of this derivative is far from being manifest. That to say of a derivative
of stress compared to a value of imposed pressure which would be worth 1,983? Without same speech of
units… How to interpret these results? As we have just seen it, Code_Aster calculates one
partial derivative. The use of the derivatives is double in our opinion: an aid with the comprehension of
studied phenomenon or an insertion in a more total process.
Initially, the knowledge of derived from a result compared to parameters
enriches the analysis by the phenomenon. That makes it possible for example to locate the areas where the influence of one
change is largest. In the same way, one will be able to compare the respective influence of two data
similar. If one must make a parametric study, one will be able to choose to do it only on
the most significant parameters. Attention nevertheless to compare derivative homogeneous:
sensitivities to an external pressure and a pressure interns for example.
Into the second time, one will be able to inject the values of the derivative obtained in a process
iterative. It is the case of the algorithms of optimization, of retiming, which converge while being based on
value of the function and its derivative. It is also the case of calculations of mechanics reliability engineer
using method FORM.
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Code_Aster
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Version
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Titrate:
Note of use of calculations of sensitivity
Date
:
13/05/03
Author (S):
G. NICOLAS
Key
:
U2.08.02-A
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:
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2
An example emblematic
We will illustrate the possibilities offered by Code_Aster by examining an academic example in
mechanics. This example will be followed until the development of its command set.
We consider a formed part of three materials. This coin is embedded on its edge
left. Two pressures are applied to the higher faces. We are interested in
stresses in third material. More particularly, we would like to know the sensitivities
of these stresses to the various Young moduli and the imposed pressures.
Pressure
With
P
Pressure
B
P









Material 3:
3
3
and
E
Like let us know we it, the stress field is a function of the data:
(
)
.
method,
mesh,
geometry,
,
,
,
,
I
I
B
With
=
In accordance with the rules stated higher, Code_Aster will be able to calculate each one of the derivative
partial
3
2
1
,
,
,
,
With
.
The result
is a field expressed at the points of Gauss of each element; it is a tensor of
components
,
,
yy
xx
etc Same manner, the result
will be a field expressed with
points of Gauss of each element. Each one of its components will be the derivative partial of
corresponding component of
yy
With
xx
,
:
, etc We will obtain them thus automatically
derivative partial of all the components of the tensor of the stresses compared to each one of
parameters mentioned.
Before going further in the description of the calculation of sensitivity, we will specify the data
numerical of the problem, expressed in international system.
Material 1:
1
1
and
E
Material 2:
2
2
and
E
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Code_Aster
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Titrate:
Note of use of calculations of sensitivity
Date
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G. NICOLAS
Key
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U2.08.02-A
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33
0
430000
1
1
,
=
=










38
0
380000
2
2
,
=
=





27
0
130000
3
3
,
=
=



By solving the static problem of mechanics in plane deformation, we obtain the fields of
displacement and of stress following.
Area 1
Area 2
Area 3
Minicomputer
Maximum
Minicomputer
Maximum
Minicomputer
Maximum
X
U
­ 0,0052 0,0066 ­ 0,0072 0,0082 ­ 0,0068 ­ 0,0034
y
U
­ 0,0150 0 ­ 0,0313
­ 0,0143
­ 0,0174
­ 0,0131
xx
­ 189 468
68 192
­ 25 980
23 721
­ 20 213
­ 6 427
yy
­ 280 144
15 453
­ 8 827
23 335
­ 3 826
204
zz
­ 154 972
22 160
­ 11 165
77 065
­ 5 787
­ 1 935
xy
­ 140 950
2 859
­ 11 182
149
­ 6 466
1 974
This stage of description, the reader is invited to test his physical direction and its appreciation of
mechanical behaviors.
Question 1: To which pressures
and
, the stress field in the area n° 3 is
more sensitive?
Question 2: Which is the command of influence of the three Young moduli
3
2
1
,
,
on this same field
stresses?
If the answers are given randomly, a rapid calculation shows that 8,3% of the readers will find them
two good answers. Users of Code_Aster being experts, the rate of good answers
will be very largely higher. We will decide between them with the following question:
Subsidiary question: In which report/ratio are the maximum of the three derived ones
I
xx
in the area
n°3?
In the next chapter, we will show how to implement calculation with Code_Aster which
will answer these questions. The reader will see in chapter 4 if its answers were the maid…
0,06
0,06
0,06
0,05
0,055
0,015
0,01
1000
=
With
P
8000
=
B
P
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Code_Aster
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Version
6.4
Titrate:
Note of use of calculations of sensitivity
Date
:
13/05/03
Author (S):
G. NICOLAS
Key
:
U2.08.02-A
Page
:
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U2.08 booklet: Advanced functions and control of calculations
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3
How to set up a calculation of sensitivity
3.1 Essence
A calculation of sensitivity is done thanks to the introduction of the concept of “significant parameter”. Otherwise
known as, if one wants to derive compared to the Young modulus from the one from materials from the field, one will define one
“significant parameter” which will represent this Young modulus. This parameter will be seen under two aspects:
·
like a constant equalizes with the face value of the Young modulus,
·
as a concept by report/ratio to which one can derive.
For each desired derivation, one will carry out the following operations:
·
to define the significant parameter with its value by the control:
DEFI_PARA_SENSI
,
·
to use this significant parameter everywhere where its value intervenes in the controls
(loadings, materials,…),
·
to ask the operator of resolution to derive the result, with the key word
:
SENSIBILITE= (...)
.
3.2
To define the significant parameters
To define a significant parameter meets this double aim: to introduce into calculation a concept which is
equal to the face value of the data and which is recognized like “sensitive”. For that, one uses
order
DEFI_PARA_SENSI
[U4.31.06]. Its syntax is similar to that well-known of
DEFI_CONSTANTE
:
AP = DEFI_PARA_SENSI (VALE = 1000.)
One must thus thus define all the significant parameters of simulation.
We draw the attention to this
: the definition of a significant parameter does not engage
automatically the calculation of the derivative. Calculation will be made only for the indicated parameters
later on. One can thus define much a priori and, for a given simulation, not derive of it
that compared to some, even none. The thus definite data in excess will be used
like simple constants.
In our example, we will define has minimum the five parameters for which we want to obtain
derivatives:
PA=DEFI_PARA_SENSI (VALE=1000.)
PB=DEFI_PARA_SENSI (VALE=8000.)
E1=DEFI_PARA_SENSI (VALE=430000.)
E2=DEFI_PARA_SENSI (VALE=380000.0)
E3=DEFI_PARA_SENSI (VALE=130000.0)
In accordance with the preceding remark, nothing prohibits to us to define other parameters
sensitive, even if we do not intend to be useful to us about it a priori.
NU3=DEFI_PARA_SENSI (VALE=0.27)
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Code_Aster
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Titrate:
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3.3
To use the significant parameters
The data associated with a significant parameter intervenes in general in a loading or in
definition of a material. Each one of these controls will be activated by providing the parameter
sensitive like input. This input will be seen by the control like a constant function being worth
the value declared in the definition of the parameter.
In our example, the loadings in pressure will be declared as follows:
pressure =
AFFE_CHAR_MECA_F (MODELE=modele
PRES_REP= (_F (GROUP_MA=' BORD_H_1',
PRES=PA),
_F (GROUP_MA=' BORD_H_2',
PRES=PB)
)
)
The definition of three materials does without the same manner:
MATER_1 = DEFI_MATERIAU (ELAS_FO=_F (E=E1, NU=NU1))
MATER_2 = DEFI_MATERIAU (ELAS_FO=_F (E=E2, NU=NU2))
MATER_3 = DEFI_MATERIAU (ELAS_FO=_F (E=E3, NU=NU3))
One will note that to use a concept of the type “parameter significant” instead of a numerical value
imply to use the definitions by functions of the loadings or materials. However, that remains
similar to the cases where the values are defined by concepts of the type “constant”, technique well
known users of Code_Aster.
3.4
To launch the derivation of the main field
Once the significant parameters were defined and used, it only remains to launch derivation.
That is done while inserting the key word
SENSITIVITY
in the operator of calculation. This key word is followed
list parameters by report/ratio to which one wishes to derive [U4.50.02]. In our example, us
let us have:
resultat=MECA_STATIQUE (
MODELE=modele,
CHAM_MATER=ch_mater,
EXCIT= (_F (CHARGE=encastre
),
_F (CHARGE=pression)),
SENSIBILITE= (E1, E2, E3, AP, PB))
This control will calculate simultaneously the field of displacements and the five field of the derivative
this same displacement compared to each definite significant parameter. All these fields
are expressed on the nodes of the mesh.
For each type of problem, we will obtain the derivation of the main field thus:
temperature in thermics, displacement in static mechanics, etc
3.5
To derive the secondary fields
Main field, are deduced from the secondary fields: heat transfer rate, deformations, forced,
etc These operations are activated by the controls
CALC_ELEM
and
CALC_NO
. Thus the tensor of
stresses is created by:
resultat=CALC_ELEM (reuse =resultat,
RESULTAT=resultat,
MODELE=modele,
CHAM_MATER=ch_mater,
EXCIT= (_F
(CHARGE=encastre),
_F (CHARGE=pression),
OPTION=
(“SIEF_ELGA_DEPL”,
“SIEF_ELNO_ELGA”)
)
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Code_Aster
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Titrate:
Note of use of calculations of sensitivity
Date
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13/05/03
Author (S):
G. NICOLAS
Key
:
U2.08.02-A
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To obtain the derivative of the stresses, it is enough to insert the key word
SENSITIVITY
follow-up of the list of
significant parameters concerned.
resultat=CALC_ELEM (reuse =resultat,
RESULTAT=resultat,
SENSIBILITE= (E1,
E2,
E3,
AP,
PB),
MODELE=modele,
CHAM_MATER=ch_mater,
EXCIT= (_F
(CHARGE=encastre),
_F (CHARGE=pression),
OPTION=
(“SIEF_ELGA_DEPL”,
“SIEF_ELNO_ELGA”)
)

resultat=CALC_NO (reuse=resultat,
RESULTAT=resultat,
SENSIBILITE= (E1,
E2,
E3),
OPTION=' SIGM_NOEU_DEPL')
Note:
·
When the key word
SENSITIVITY
is inserted in a control
CALC_ELEM
or
CALC_NO
, only the derived field is calculated.
·
To calculate the derivative of a field to the elements, it is necessary as a preliminary to have calculated it
standard field. On the other hand, that is useless for a field with the nodes because the operator
CALC_NO
is satisfied to make an average with the nodes of a field to the elements.
3.6
Post-to treat the results
To print the fields of derivatives, it is enough to insert the key word
SENSITIVITY
in the control
IMPR_RESU
. Here still, that will start only the impression of the derived fields compared to
parameters concerned:
IMPR_RESU (RESU=_F (FORMAT=' MED',
RESULTAT=resultat)
)

IMPR_RESU (RESU=_F (FORMAT=' MED',
RESULTAT=resultat,
SENSIBILITE= (E1, E2, E3, AP, PB)))
All the options of the control are obviously accessible.
IMPR_RESU (RESU=_F (RESULTAT=resultat,
SENSIBILITE=
(E1,
E2,
E3,
AP,
PB),
NOM_CHAM=
“SIEF_ELGA_DEPL”,
GROUP_MA=' ZONE_3',
VALE_MAX=' OUI',
VALE_MIN=' OUI')
)
Beyond the impression, all the controls which handle the results were equipped with
key word
SENSITIVITY: EXTR_RESU, POST_RELEVE_T
etc Operation is similar to
standard: the control carries out the operation required but on the selected derived fields and
exclusively on them.
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Code_Aster
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Titrate:
Note of use of calculations of sensitivity
Date
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:
U2.08.02-A
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4
Example: calculation, comments and results
Here the complete command set associated the example describes in chapter 2.
BEGINNING (CODE=_F (NOM=' SENSM06A', NIV_PUB_WEB=' INTERNET'))
#
# 1. Mesh
# 1.1. Reading of the mesh
#
PRE_GMSH (MODI_QUAD=' OUI')
maill_0=LIRE_MAILLAGE ()
#
# 1.2. Naming of the groups
#
maill_0= DEFI_GROUP (reuse =maill_0,
MAILLAGE=maill_0,
CREA_GROUP_MA
= (
_F (GROUP_MA=' GM11', NOM=' BORD_H_1'),
_F (GROUP_MA=' GM12',
NOM=' BORD_H_2'),
_F (GROUP_MA=' GM13',
NOM=' BORD_GAU'),
_F (GROUP_MA=' GM21',
NOM=' ZONE_1'),
_F (GROUP_MA=' GM22',
NOM=' ZONE_2'),
_F (GROUP_MA=' GM23', NOM=' ZONE_3')),
CREA_GROUP_NO=_F (GROUP_MA= (“GM1”, “GM2”, “GM3”, “GM4”),
NOM= (“COIN_BG”, “COIN_BD”, “COIN_HD”, “COIN_HG”)))
#
# 2. Definition of the functions
# 2.1. Definition of the significant parameters
#
PA=DEFI_PARA_SENSI (VALE=1000.)
PB=DEFI_PARA_SENSI (VALE=8000)
E1=DEFI_PARA_SENSI (VALE=430000.)
E2=DEFI_PARA_SENSI (VALE=380000.)
E3=DEFI_PARA_SENSI (VALE=130000.)
NU3=DEFI_PARA_SENSI (VALE=0.27)
#
# 2.2 Definition of the constants
#
NU1=DEFI_CONSTANTE (VALE=0.33)
NU2=DEFI_CONSTANTE (VALE=0.38)
#
# 3. Definition of materials
#
mater_1=DEFI_MATERIAU (ELAS_FO=_F (E=E1,
NU=NU1)
)

mater_2=DEFI_MATERIAU (ELAS_FO=_F (E=E2,
NU=NU2)
)

mater_3=DEFI_MATERIAU (ELAS_FO=_F (E=E3,
NU=NU3)
)
#
# 4. The model
#
modele=AFFE_MODELE (MAILLAGE=maill_0,
AFFE=_F
(
TOUT=' OUI',
PHENOMENE=' MECANIQUE',
MODELISATION=' D_PLAN'))
#
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Titrate:
Note of use of calculations of sensitivity
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# 5. Loadings
#
encastre=AFFE_CHAR_MECA (MODELE=modele,
DDL_IMPO=_F (GROUP_NO=' COIN-BG',
DY=0.0)
FACE_IMPO=_F (GROUP_MA=' BORD_GAU', DNOR=0.0))
pression=AFFE_CHAR_MECA_F (MODELE=modele,
PRES_REP= (_F (GROUP_MA=' BORD_H_1',
PRES=PA),
_F (GROUP_MA=' BORD_H_2', PRES=PB))
#
# 6. Installation of materials
#
ch_mater=AFFE_MATERIAU (MAILLAGE=maill_0,
MODELE=modele,
AFFE= (_F (GROUP_MA=' ZONE_1',
MATER=mater_1),
_F (GROUP_MA=' ZONE_2', MATER=mater_2),
_F (GROUP_MA=' ZONE_3', MATER=mater_3)) )
#
# 7. Calculation with derivations
#
resultat=MECA_STATIQUE (MODELE=modele,
CHAM_MATER=ch_mater,
EXCIT= (_F (CHARGE=encastre),
_F (CHARGE=pression)),
SENSIBILITE= (E1, E2, E3, AP, PB))
#
# 8. Other fields
# 8.1. Standard stresses
#
resultat=CALC_ELEM (reuse =resultat,
RESULTAT=resultat,
MODELE=modele,
CHAM_MATER=ch_mater,
EXCIT= (_F (CHARGE=encastre),
_F (CHARGE=pression)),
OPTION= (“SIEF_ELGA_DEPL”, “SIGM_ELNO_DEPL”))
#
# 8.2. The derivative of the stresses at the points of Gauss
#
resultat=CALC_ELEM (reuse =resultat,
RESULTAT=resultat,
SENSIBILITE= (E1, E2, E3, AP, PB),
MODELE=modele,
CHAM_MATER=ch_mater,
EXCIT= (_F (CHARGE=encastre),
_F (CHARGE=pression)),
OPTION= (“SIEF_ELGA_DEPL”, “SIGM_ELNO_DEPL”))
#
# 8.3. The derivative of the stresses to the nodes
#
resultat=CALC_NO (reuse =resultat,
RESULTAT=resultat,
SENSIBILITE= (E1, E2, E3),
EXCIT= (_F (CHARGE=encastre),
_F (CHARGE=pression)),
OPTION=' SIGM_NOEU_DEPL')
#
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Titrate:
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# 9. Impressions of the results
#
# 9.1. The standard result
#
DEFUFI (IMPRESSION=_F (NOM=' RESUGMSH', UNITE=37))
#
IMPR_RESU (RESU=_F (FORMAT=' GMSH', RESULTAT=resultat,
FICHIER=' RESUGMSH'))
#
IMPR_RESU (RESU=_F (FORMAT=' MED',
RESULTAT=resultat))
#
# 9.2. The result of the derivative
#
IMPR_RESU (RESU=_F (FORMAT=' MED',
RESULTAT=resultat,
SENSIBILITE= (E1, E2, E3, AP, PB)))
#
# 9.3. Extreme values of displacement and the stresses in each
area
#
IMPR_RESU (RESU=_F (RESULTAT=resultat,
NOM_CHAM= (“DEPL”,
“SIEF_ELGA_DEPL”),
GROUP_MA=' ZONE_1',
VALE_MAX=' OUI',
VALE_MIN=' OUI',
FORMAT_R='1PE12.5'))
#
IMPR_RESU (RESU=_F (RESULTAT=resultat,
NOM_CHAM= (“DEPL”,
“SIEF_ELGA_DEPL”),
GROUP_MA=' ZONE_2',
VALE_MAX=' OUI',
VALE_MIN=' OUI',
FORMAT_R='1PE12.5'))
#
IMPR_RESU (RESU=_F (RESULTAT=resultat,
NOM_CHAM= (“DEPL”,
“SIEF_ELGA_DEPL”),
GROUP_MA=' ZONE_3',
VALE_MAX=' OUI',
VALE_MIN=' OUI',
FORMAT_R='1PE12.5'))
#
# 9.4. Extreme values of derived from the stresses in area 3
#
IMPR_RESU (RESU=_F (RESULTAT=resultat,
SENSIBILITE= (E1, E2, E3, AP, PB),
NOM_CHAM=' SIEF_ELGA_DEPL',
GROUP_MA=' ZONE_3',
VALE_MAX=' OUI',
VALE_MIN=' OUI',
FORMAT_R='1PE12.3'))
#
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Titrate:
Note of use of calculations of sensitivity
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# 9.5. Test of nonregression on a component of derived from stress
#
TEST_RESU (RESU=_F (RESULTAT=resultat,
SENSIBILITE=E3,
NOM_CHAM=' SIGM_NOEU_DEPL', NOM_CMP=' SIXX',
NUME_ORDRE=1, GROUP_NO=' COIN_BD',
VALE=3.160121E-5, CRITERE=' RELATIF', PRECISION=1e-05,
REFERENCE=' NON_REGRESSION'))
#
END ()


It is time to approach the result of our contest of chapter 2. Here extreme values of
derived from the stresses compared to the two pressures
and
, in area 3.
Derived compared to
Derived compared to
Minicomputer
Maximum
Minicomputer
Maximum
xx
­ 0,0068 0,0868 ­ 2,537 ­ 0,8063
yy
­ 0,0107 0,0107 ­ 0,4770 0,0256
zz
­ 0,0046 0,0245 ­ 0,7264 ­ 0,2427
xy
­ 0,0206 0,0050 ­ 0,8057 0,0250
We note that the stress field is more sensitive to
that with
, the maximum report/ratio
being located between 30 and 50.
For question 2 and the subsidiary question, we examine in the area n° 3, the extreme values
derivative of the stress field compared to the three Young moduli
3
2
1
,
and
.
Derived compared to
1
Derived compared to
2
Derived compared to
3
Maximum Mini minicomputer Maximum Mini Maximum
xx
­ 0,0014 0,0127 ­ 0,0023 0,0173 ­ 0,0577 ­ 0,0273
yy
­ 0,0052 0,0043 ­ 0,0083 0,0021 ­ 0,0008 0,0161
zz
­ 0,0009 0,0044 ­ 0,0024 0,0049 ­ 0,0157 ­ 0,0043
xy
­ 0,0028 0,0068 ­ 0,0046 0,0048 ­ 0,0182 0,0075
background image
Code_Aster
®
Version
6.4
Titrate:
Note of use of calculations of sensitivity
Date
:
13/05/03
Author (S):
G. NICOLAS
Key
:
U2.08.02-A
Page
:
13/14
Instruction manual
U2.08 booklet: Advanced functions and control of calculations
HI-23/03/002/A
On these results, we note that the first two Young moduli have the same one roughly speaking
influence on the stress field in the area n° 3, with a light preponderance of
2
. But
their influence is overridden by that of the third parameter
3
. If we look at the maxima
of sensitivity in absolute value, we have the following reports/ratios:

max
1
max
2
max
3
54
,
4
33
,
3
xx
xx
xx
=
=
max
1
max
2
max
3
10
,
3
94
,
1
yy
yy
yy
=
=
max
1
max
2
max
3
57
,
3
20
,
3
zz
zz
zz
=
=
max
1
max
2
max
3
68
,
2
79
,
3
xy
xy
xy
=
=

Congratulations with the readers who will have found the good solutions!
background image
Code_Aster
®
Version
6.4
Titrate:
Note of use of calculations of sensitivity
Date
:
13/05/03
Author (S):
G. NICOLAS
Key
:
U2.08.02-A
Page
:
14/14
Instruction manual
U2.08 booklet: Advanced functions and control of calculations
HI-23/03/002/A
5 Comments
Generals
5.1
Automation of the analysis of the controls
An attentive user who will consult the file of the messages produced by Code_Aster will see that, by
report/ratio from what had been requested, more controls were carried out. It is completely
normal. The computing process of sensitivity needs to derive the unit from the controls where
intervene the significant parameters. A preprocessing of the command set thus will duplicate
each control by replacing its arguments by the derived arguments. New concepts
are created, whose names are establish by an automatic mechanism. They are memorized in-house
with calculation by the control
MEMO_NOM_SENSI
. Their knowledge does not have any interest for the user
insofar as all information is accessible by a couple (name from standard concept,
significant name of parameter). In short, we can say that the maximum was made to simplify
the task of the user.
Nevertheless, a reserve is essential: this mechanism of preprocessing is available only for
processing of the orders by batches. It is the default option besides of the control
BEGINNING
. Thus
any command set produced by editor EFICAS by preserving the batch processing will be interpreted
correctly. For a advanced use of the command set which involves the inactivation of
batch processing, the automatic insertion of the derived controls does not take place. It is what occurs
when one modifies with the hand the command set to insert basic Python instructions there. It is necessary
then to make with the hand work derivation of the controls, the ones after the others, while memorizing
names of the produced concepts.

5.2 Performance
The calculation of a derivative is increasingly faster than the calculation of the minimal size.