Code_Aster
®
Version
6.4
Titrate:
Great principles of operation of Code_Aster
Date:
26/06/03
Author (S):
J.M. PROIX, J.R. LEVESQUE
Key
:
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:
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Organization (S):
EDF-R & D/AMA
Instruction manual
U1.0- booklet: Synoptic
Document: U1.03.00
Great principles of operation
of Code_Aster
Summary:
One presents here in a summary way the principles of operation of Code_Aster and the main rules
of use.
This document remains a general description and the reader will refer usefully to the other documents, for all
details of use.
Code_Aster
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Version
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Titrate:
Great principles of operation of Code_Aster
Date:
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Key
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1 Principles
Generals
Version 6 of the Code Aster makes it possible to carry out structural analyzes for the phenomena
thermics, mechanics, thermomechanical, or thermo hydro-mechanical coupled, with one
or not linear linear behavior, and of calculations of internal accoustics.
Nonthe linearities relate to the behaviors of the materials (plasticity, viscoplasticity,
damage, effects metallurgical, hydration and drying of the concrete,…), the large ones
deformations or great rotations and the contact with friction. One will refer to the plate of
presentation of version 6 for the presentation of the various functionalities.
The current industrial studies require the placement of tools of mesh and visualization
graph, which does not form part of the Code. However, several tools are usable for these
operations via procedures of interface integrated into the Code.
To make a study, the user must, in general, prepare two data files:
·
the file of mesh:
to define geometrical and topological description mesh without choosing, at this stage the type
of formulation of the finite elements used or the physical phenomenon to modelize. Some
studies can result in using several files of mesh.
This file of mesh, in general, is produced by an interface integrated into the Code Aster to leave
of a file coming from a software of mesh used out of preprocessor (GIBI, GMSH, IDEAS…).
Information which this file must contain is specific to Code_Aster. They define
conventional entities of the finite element method:
·
nodes: points defined by a name and their Cartesian co-ordinates in
space 2D or 3D,
·
meshs: plane or voluminal named topological figures (not, segment, triangle,
quadrangle, tetrahedron,…) to which will be able to apply various types of elements
stop, boundary conditions or loadings.
To improve safety of use and comfort of the operations of modeling and of
examination of the results, one can define, in the file of mesh, of the levels of entities
superiors, having an unspecified property jointly and who could be used
directly by their name:
·
groups of nodes: named lists of names of nodes,
·
groups of meshs: named lists of names of meshs.
One will note, as of now, that all handled geometrical entities (nodes, meshs,
groups of nodes, groups of meshs) are named by the user and usable with all
moment by their name (8 characters to the maximum). The user will be able to use this possibility
to identify explicitly certain parts of the studied structure and to thus facilitate it
examination of the results. The classification of the entities is never clarified: it is useful
only in-house to point on the values of the various associated variables.
·
the command file: to define the text of control which allows:
-
of reading and if required enriching the data of the file by mesh (or other sources of
external results),
-
to affect the data of modeling on the entities of the mesh,
-
to connect various operations of processing: specific calculations, postprocessings,
-
to publish the results on various files.
The text of control refers to the names of geometrical entities defined in the file of
mesh. It also makes it possible to define new groups constantly.
Code_Aster
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From the data-processing point of view, these two files are ASCII files in free format. One gives some here
outstanding features:
Syntax of the file of mesh:
·
length of line limited to 80 characters,
·
the allowed characters are:
-
26 tiny capital letters A-Z and 26 a-z converted automatically in capital letters,
except in the texts (provided between quotes),
-
ten figures 0-9 and signs of representation of the numbers (+ -. ),
-
character
_ white underlined usable in key words or names,
·
a word must always start with a letter,
·
the white character is always a separator,
·
the character % indicates the beginning, until the end of the line, of a comment.
·
The other rules of reading are specified in the booklet [U3.01.00]
Syntax of the command file:
·
syntax related to the language Python, allowing to include instructions of this language
·
character # indicates the beginning, until the end of the line, of a comment.
·
The controls must start in column 1, unless they do not belong to a block
indenté (loops, test)
The other rules of reading are specified in the booklet [U1.03.01].
2 Mesh
2.1 General
The structure and the syntax of the file of mesh are detailed in the Booklet [U3.01.00].
This file can be written (for elementary mesh) or be modified manually with does not import
which text editor. It is a file read in free format, structured in records or under
file by imposed key words.
Several utilities of conversion are available to allow the file conversion of mesh
products by other software packages (IDEAS, GIBI, GMSH…) or of the files of mesh to format MED.
2.2
The file of mesh Aster
The file of Aster mesh is read first line until the first occurrence of a line
begin with the word
END
. This key word is obligatory. The file of mesh is structured in
independent subfiles starting with a key word and finished by the key word imposed FINSF.
This file must comprise at least two subfiles:
·
co-ordinates of all the nodes of the mesh in a Cartesian reference mark 2D (COOR_2D) or 3D
(COOR_3D).
·
the description of all meshs (TRIA3, HEXA20, etc…), on which one will affect then
physical properties, finite elements, boundary conditions or loadings.
It can possibly contain groups of nodes (
GROUP_NO
) or of meshs (
GROUP_MA
) for
to facilitate the operations of assignment, but also the examination of the results.
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It is essential to explicitly create at this stage the meshs located on the borders
of application of the loadings and boundary conditions. One will find then, in the file of
mesh:
·
meshs of edge of the elements 2D necessary,
·
meshs of face of the elements 3D solid masses necessary;
·
groups of meshs of associated edge and/or face.
This stress becomes bearable when one uses an interface, which does the work from
indications provided at the time it mesh (see the documents
PRE_IDEAS
[U7.01.01] or
PRE_GIBI
[U7.01.11]).
2.3
The description of the meshs
Conventions of description of the topology of the meshs and conditions of use of different
types of meshs are described in the booklet [U3.01.00].
The main types of meshs recognized are identified by the following reserved key words [U3.01]:
/POI1
specific mesh
/SEG2/
SEG3/SEG4
segments with 2, 3, or 4 nodes
/TRIA3/TRIA6/TRIA7
triangles with 3, 6 or 7 nodes
/QUAD4/QUAD8/QUAD9
quadrangles with 4, 8 or 9 nodes
/HEXA8/HEXA20
/HEXA27
hexahedrons with 8, 20 or 27 nodes
/
PENTA6
/
PENTA15
pentahedrons with 6 or 15 nodes
/
TETRA4
/
TETRA10
tetrahedrons with 4 or 10 nodes
/
PYRAM5
/
PYRAM13
pyramids with 5 or 13 nodes
2.4
interfaces
These interfaces make it possible to convert the files, with or without format, used by different
computer software package or codes, with the conventional format of the file of mesh Aster.
The currently available interfaces are those which make it possible to use maillor IDEAS, it
maillor GIBI of CASTEM 2000, maillor GMSH, and to treat the files of mesh with the format
of exchange MED.
2.4.1 Universal file IDEAS
The interface is made using the control
PRE_IDEAS
[U7.01.01]
The convertible file is the universal file defined by documentation I-DEAS (see Fascicule
[U3.03.01]). The reconnaissance of version IDEAS used is automatic.
A universal file IDEAS consists of several independent blocks called “dated sets”.
Each “set dated” is framed by the character string - 1 and is numbered. “Dated recognized sets”
by the interface are described in the booklet [U3.03.01].
2.4.2 The file of mesh GIBI
The interface is made using the control
PRE_GIBI
[U7.01.11]).
The convertible file is the ASCII file restored by the control
TO SAVE
FORMAT
CASTEM 2000.
The precise description of the interface is given in [U3.04.01].
2.4.3 The file of mesh GMSH
The interface is made using the control
PRE_GMSH
[U7.01.31]).
The convertible file is the ASCII file restored by the control
SAVE of GMSH
.
Code_Aster
®
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Titrate:
Great principles of operation of Code_Aster
Date:
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2.4.4 The file of mesh to format MED
The interface is made using the control
LIRE_MAILLAGE
(FORMAT:“MED”)
[U4.21.01]).
MED (Modeling and Data exchanges) is a neutral format of data developed by EDF
R & D for the data exchanges between computer codes. Files MED are binary files
and portables. Reading of a file MED by
LIRE_MAILLAGE
, allows to recover a mesh
product by any other code able to create a file MED on any other machine. This format of
data is in particular used for the exchanges of files of mesh and results between ASTER
and the tool of refinement of mesh LOBSTER. The precise description of the interface is given in
[U7.01.21].
2.5
The use of incompatible mesh
Although the finite element method recommends the use of regular mesh, without
discontinuity, to obtain a correct convergence towards the solution of the continuous problem, it can be
necessary for certain modelings to use incompatible mesh: on both sides
of a border, the mesh does not correspond. The connection of this two mesh is
then managed on the level of the command file by the key word
LIAISON_MAIL
control
AFFE_CHAR_MECA
. This makes it possible in particular to finely connect an area with a grid with another
area where one can be satisfied with a coarse mesh.
2.6
Adaptive mesh
Starting from an initial mesh, it is possible to adapt the mesh, to minimize the made error, with
the aid of the macro control
MACR_ADAP_MAIL
, which calls upon the software LOBSTER. Software of
adaptive mesh LOBSTER functions on mesh made of segments, triangles, tetrahedrons.
This adaptation of mesh is placed after the first calculation with Code_Aster. An indicator of
the error will have been calculated. According to its value nets by mesh, the software LOBSTER will modify it
mesh. It is also possible to interpolate fields of temperature or displacement with
nodes of the old mesh towards the new one [U7.03.01].
3 Controls
3.1
The command file
The command file contains a whole of controls, expressed in a specific language
in Code_Aster. In complement of the characteristics of file described in paragraph 1, one will find
the detailed syntax of the language in the booklet [U6.02.00]. These controls are analyzed and
carried out by a software layer of Code_Aster called “supervisor”.
3.2
The role of the supervisor
The supervisor carries out various tasks, in particular:
·
a phase of checking and interpretation of the command file,
·
a production run of the interpreted controls.
These tasks are detailed in the booklet [U1.03.01].
The command file is treated starting from the line where the first call to the procedure is
BEGINNING ()
or with the procedure
CONTINUATION (),
and until the first occurrence of the control
END ()
. Controls located front
BEGINNING ()
or
CONTINUATION ()
and afterwards
END ()
are not
carried out, but must be syntactically correct).
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·
Syntactic phase of checking:
-
reading and syntactic checking of each control; any error of detected syntax makes
the object of a message, but the analysis continues,
- checking that all the concepts used as arguments were declared in one
order preceding like produced concept of an operator; it is also checked that the type
this concept corresponds to the type required for this argument.
·
Production run:
-
the supervisor activates successively the various operators and procedures, which carry them out
tasks envisaged.
3.3
Principles and the syntax of the process control language
The modular concept of Aster makes it possible to present the Code like a succession of controls
independent:
·
the procedures, which do not produce results directly, but ensure, amongst other things,
management of the exchanges with the external files,
·
the operators, who carry out an operation of calculation or data management and produce one
concept result to which the user gives a name.
These concepts represent structures of data, that the user can handle. These concepts
are typified at the time of their creation and could be used only as argument of input of
corresponding type.
The procedures and the operators thus exchange information necessary and of the values by
the intermediary of the named concepts
The complete syntax of the controls and its implications on the drafting of the command file
are detailed in the booklet [U1.03.01]. Here an example of some controls is given
(extracted the example with accompanying notes in [U1.05.00]):
mall = LIRE_MAILLAGE ()
mod1 = AFFE_MODELE (MESH = mall,
AFFE=_F (TOUT=' OUI',
PHENOMENE=' MECANIQUE',
MODELISATION=' AXIS'))
f_y = DEFI_FONCTION (NOM_PARA = “Y”
VALE =_F (0., 20000.,
4., 0. )
)
charg = AFFE_CHAR_MECA_F (MODEL = mod1
PRES_REP =_F (GROUP_MA = (“lfa”, “ldf”),
CLOSE = f_y))
.....
res1 = MECA_STATIQUE (MODELE=mod1,
......
EXCIT=_F (LOAD = charg),
….)
res1 = CALC_ELEM (reuse=res1, RESULTAT=res1,
...........
MODELE=mod1,
OPTION= (“SIGM_ELNO_DEPL”, “EPSI_ELNO_DEPL”))
Code_Aster
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Some general points will be noted, which one can observe on the preceding example:
·
any control starts in first column,
·
the list of the operands of a control is obligatorily between brackets, as well as the lists
elements,
·
one
nom_de_concept
can appear only only once in the text of control like
produced concept, on the left of the sign =,
·
the re-use of an existing concept like produced concept, is not possible that for
operators specified to this end. When one uses this possibility (réentrant concept),
control uses the reserved key word then “reuse”.
This operation is done:
·
maybe with crushing of the initial values. As example let us announce factorization in place
of a matrix of rigidity:
matass = FACT_LDLT (reuse=matass, MATR_ASSE= matass)
·
maybe with enrichment of the concept.
3.4
Regulate of overload
A rule of overload usable, in particular for all the operations of assignment, was added
with the rules of use of one
mot_cle_factor
with several lists of operands:
·
the assignments are done by superimposing the effects of different
mot_clé
,
·
in the event of conflict, the last
mot_clé
overrides the precedents.
Example: one wishes to affect various materials
MAT1
,
MAT2
and
MAT3
with certain meshs:
to subdue = AFFE_MATERIAU (MAILLAGE= mon_mail
AFFE = _F (ALL = “YES”, MATER = MAT1),
_F (GROUP_MA = “MAIL2”, MATER = MAT2),
_F (GROUP_MA = “MAIL1”, MATER = MAT3),
_F (MESH = (“M7”, “M8”), MATER = MAT3))
·
One starts by affecting material
MAT1
with all the meshs.
·
One affects then material
MAT2
with the group of meshs
mail2
who contains, the meshs
m8
,
m9
and
m10
.
·
One affects finally material
MAT3
with the group of meshs
mail1
(m5, m6
and
m7)
and with the meshs
m7
and
m8
, which causes conflict since the mesh
m7
fact already part of the group
mail1
.
regulate of overload will then be applied and one will obtain finally the field of following material:
MAT1
:
meshs
m1 m2 m3 m4
MAT2
:
meshs
m9 m10
MAT3
:
meshs
m5 m6 m7 m8
3.5
Data bases associated with a study
Code_Aster rests, for the management of all the structures of data associated with different
concepts handled, on software package JEVEUX. The aforementioned deals with the space management
memory asked by the user at the time of the request for execution (parameter Report expressed in
Megabytes). This space is frequently insufficient to store central all them
structures of data. The software package takes then charges some, the management of the exchanges between the memory
power station and of the auxiliary storages on files.
Each entity is affected, during its creation by the code, with a file of random access. The aforementioned can
to be regarded as a data base, since it contains, at the end of the execution the index
(names and attributes) which makes it possible to exploit all the segments of values that it contains.
Code_Aster
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Code_Aster uses several data bases:
·
the data base
TOTAL,
who contains all the concepts produced by the operators, thus
that contents of certain catalogs on which the concepts are pressed; the file associated with
this the later continuation of a study allows. It must thus be managed by the user.
·
other data bases, used only by the Supervisor and the operators, with the course
of an execution, do not require a particular intervention of the user.
To make a study, it is to ask for the sequence of several controls:
·
procedures to exchange files with the external world,
·
operators to create concepts progressively produces course of operation
of modeling and calculation.
The controls which correspond to this sequence of operations can be carried out of
various ways, starting from the single executable module of Code_Aster:
·
in only one sequential execution, without intervention of the user,
·
by splitting the study in several successive executions, with re-use of the results
former; starting from the second execution, the access to the data base is done in continuation; with
the occasion of a continuation, one can redemander the last control, if it stopped
prematurely (lack of time, incomplete or incorrect data detected in phase
of execution,…).
order 1
order 2
·
·
order I
order i+1
·
·
order J
order j+1
·
·
order N
Study
order 1
order 2
·
·
order I
order i+1
·
·
order J
order j+1
·
·
order N
Continuation
Continuation
Beginning
Study
The continuation is not possible
that within the framework of one
even version
End
End
End
To manage these possibilities, it will be noted that three controls play a primordial part. They are those
who correspond to the procedures which activate the supervisor:
·
BEGINNING ()
obligatory for the first execution of a study,
·
CONTINUATION ()
obligatory starting from the second execution of a study,
·
END ()
obligatory for all the executions.
For a given study, one can subject command files having the following structure:
Note:
·
The control
INCLUDE
allows to include in a flood of controls the contents of another
command file. This allows in particular, to preserve a file of the controls
main readable and to place in annexed files of the numerical data
bulky (ex: definition of functions).
·
The command files can be cut out in several files which will be carried out
one after the other, with intermediate backup of the data base. For that, it is necessary
to define the successive command files, whose suffix will be:
.com1
,
.com2
,…,
.com9
.
The executions of these files are connected. The data base of the last execution
who finished well is preserved.
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3.6
Contribute to the definition of the values
3.6.1 Substitution of values
Several controls are available to help the user to define the values used like
arguments, therefore to parameterize its command file:
·
to give a name to one or more values:
name = DEFI_VALEUR (STANDARD = [value]);
or quite simply:
name = value
·
To evaluate certain mathematical expressions:
EVAL (expression)
For example:
Eptub = 26.187E-3
Rmoy = 203.2E-3
Rext = DEFI_VALEUR (R8 = EVAL (""" Rmoy+ (EPtub/2) """))
= AFFE_CARA_ELEM (MODEL will cara = model
BEAM =_F (GROUP_MA = all, SECTION: “CIRCLE”,
CARA = (“R”, “EP”), VALE = (Rext, EPtub)))
These possibilities result in a simple substitution of the values each time the Supervisor
meet the name chosen by the user.
3.6.2 Functions of one or more parameters
It is also often necessary to use sizes functions of other parameters.
Those can be:
·
that is to say definite on an external file read by the control,
LIRE_FONCTION
.
·
that is to say defined in the command file by:
-
DEFI_CONSTANTE
product a concept
function
with only one constant value,
-
DEFI_FONCTION
product a concept
function
for a size function of one
real parameter,
-
DEFI_NAPPE
product a concept
function
for a list of functions of same
size, each element of the list corresponding to a value of another parameter
reality.
The concept produced by these operators is of type
function
and can only be used
as argument of operands which accept this type. The operators who accept one
argument of the type
function
have as a suffix
F
(ex:
AFFE_CHAR_MECA_F
). Functions
in this case are defined point by point, with a linear interpolation by defect, therefore
closely connected by pieces.
The functions created are discrete tables of the sizes specified with creation.
At the time of a search for value, one proceeds according to the specified characteristics, by
direct search or by interpolation in the table (linear or logarithm). One can
to specify, during the creation of the function, the prolongation out of the field of definition
table, with various rules, or to prohibit it.
·
that is to say definite using their analytical expression by the operator
FORMULATE
: for example:
Omega = 3.566;
linst = (0., 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10,
0.20, 0.40)
F = FORMULA (REAL = ''' (REAL:INST) = COS (OMEGA * INST) ''')
F1=CALC_FONC_INTERP (FONCTION=F, VALE_R= linst,
NOM_RESU=' ACCE',)
Code_Aster
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The analytical function F (T) =cos (
T) is then calculated by
CALC_FONC_INTERP
for the moments of
the list
linst
list moments T.
3.7
How to write its command file with EFICAS?
To write a command file of Code_Aster, most immediate consists starting from an example
already written by others. In particular, the whole of the tests of Code_Aster often constitutes one
good starting base for a new modeling.
But there is better: tool EFICAS makes it possible to write in an interactive and user-friendly way its file of
controls, by proposing for each control the list of the possible key words while checking
automatically syntax, and by giving access to the documentation of the Instruction manual
(booklets [U4] and [U7]).
4
Great stages of a study
The great stages of a study are in the general case:
·
the preparation of the work, which finishes after the reading of the mesh,
·
the modeling during which are definite and affected all the properties of
finite elements and of materials, boundary conditions and loadings,
·
calculation can then be carried out by the execution of total methods of resolution [U4.5-], which
are possibly based on controls of calculation and assembly of matrix and
vectors [U4.6-]
·
operations of postprocessings complementary to calculation [U4.8-],
·
operations of impression of the results [U4.9-]
·
operations of exchange of results with other software (graphic visualization by
example) [U7.05-]
Another way of using Code_Aster consists in exploiting tools trades, available in
Code in the form of MACRO_COMMANDES: let us quote for example the tools trades:
·
ASCOUF (modeling of fissured elbows or elbows with under-thicknesses),
·
ASPIC (modeling of or not fissured fissured prickings),
·
GOUJ2ECH (modeling of the behavior of the threaded assemblies).
4.1
To start the study and to acquire the mesh
One will not reconsider here the possible fragmentation of the command file, which was presented
in a preceding paragraph.
The first executable control is:
BEGINNING
()
The argument of this control are useful only for the maintenance actions or in
case of very large studies.
For the reading of the mesh, coming from a software of external mesh, one can operate of two
ways:
·
to convert the file of a software package by a separated execution, which allows, if required,
to modify it by word processing and to preserve it:
BEGINNING
()
PRE_IDEAS
()
END
()
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6.4
Titrate:
Great principles of operation of Code_Aster
Date:
26/06/03
Author (S):
J.M. PROIX, J.R. LEVESQUE
Key
:
U1.03.00-D
Page
:
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Instruction manual
U1.0- booklet: Synoptic
HT-66/03/002/A
the normal study will be able to then begin for example by:
BEGINNING
()
my = LIRE_MAILLAGE
()
·
to convert the file right before reading it:
BEGINNING
()
PRE_IDEAS
()
my = LIRE_MAILLAGE
()
4.2
To assign data of modeling to the mesh
To build the modeling of a mechanical problem, thermal or acoustic, it is
essential to assign to the topological entities mesh:
·
a model of finite element,
·
properties of the materials (law of behavior and parameters of the law),
·
geometrical or mechanical characteristics complementary,
·
boundary conditions or loadings.
These assignments are obtained by various operators whose name is prefixed by
AFFE_
.
syntax and the operation of these operators already uses the facilities brought by the rules
mentioned previously on the use of the key words factor.
4.2.1 Definition of a field of assignment
To carry out an assignment, it is essential to define a field of assignment per reference to
names of the topological entities defined in the file mesh. Five key words are usable for
that, according to the specification of the operator:
·
to refer to all the mesh by
TOUT= “YES”
·
to assign to meshs by
MAILLE=
(list of names of meshs)
·
to assign to groups of meshs by
GROUP_MA=
(list of names of groups of meshs)
·
to assign to nodes by
NOEUD=
(list of names of nodes)
·
to assign to groups of nodes by
GROUP_NO=
(list of names of groups of nodes)
4.2.2 To affect the type of finite element
On the meshs of the studied structure, which are at this stage only topological entities, it is
essential to affect:
·
one or more phenomena studied:
“MECHANICAL”,
“THERMAL”, “ACOUSTIC”
;
·
a model of finite element compatible with the topological description of the mesh. This
assignment induces an explicit list of degrees of freedom in each node and a law
of interpolation in the element.
One uses for that the operator
AFFE_MODELE
[U4.41.01], which can be called several times on
even mesh. It uses the rules of overload and remanence.
Note:
For a study with several treated phenomena (
“MECHANICAL”
,
“THERMAL”
), it is
essential to build a model for each phenomenon, by as many calls to
AFFE_MODELE
. On the other hand, for a given calculation (mechanical, thermal,…) one needs one and only one
model.
To know the characteristics of the various finite elements available one will refer to
booklets [U2-], and [U3-].
Code_Aster
®
Version
6.4
Titrate:
Great principles of operation of Code_Aster
Date:
26/06/03
Author (S):
J.M. PROIX, J.R. LEVESQUE
Key
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U1.03.00-D
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:
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Instruction manual
U1.0- booklet: Synoptic
HT-66/03/002/A
4.2.3 To affect material characteristics
It is necessary to assign to this stage characteristics of material, and the parameters associated, with
each finite element of the model (except for the directly definite discrete elements by a matrix of
rigidity, of mass and/or damping). In other words,
DEFI_MATERIAU
is used to define one
material and
AFFE_MATERIAU
is used to define a material field by association of the mesh. For one
calculation given, one needs one and only one field of material.
One can also use the validated characteristics of the catalog material using the procedure
INCLUDE_MATERIAU
[U4.43.02].
A certain number of models of behavior are usable: rubber band, orthotropic rubber band,
thermics, accoustics, elastoplastic, elastoviscoplastic, endommagment. Let us note that it is
possible to define several material characteristics for the same material: rubber band and
thermics, elastoplastic, thermo plastic,…
4.2.4 To assign characteristics to the elements
During the use of certain types of elements, for the phenomenon `
MECANIQUE'
, the definition
geometrical deduced from the mesh does not allow to describe them completely.
One must assign to the meshs the missing characteristics:
·
for the hulls: the constant thickness on each mesh and a reference mark of reference for
representation of the state of stress,
·
for the beams, bars and pipes: characteristics of the cross section, and
possibly orientation of this section around neutral fiber.
These operations are accessible by the operator
AFFE_CARA_ELEM
[U4.42.01]), which uses, for
to simplify the drafting of the control, the rules of overload and remanence.
Another possibility is offered by this operator: that to introduce, directly in the model, of
matrices of rigidity, mass or damping on meshs
POI1
(or of the nodes) or of
meshs
SEG2
. These matrices correspond to the types of discrete finite elements with 3 or 6 degrees of
freedom by node
DIS_T
or
DIS_TR
who must be affected at the time of the call to the operator
AFFE_MODELE
.
4.2.5 To affect the boundary conditions and the loadings
These operations are, in general, essential. They are carried out by several operators of which it
name is prefixed by
AFFE_CHAR
or
CALC_CHAR
. On the same model, one will be able to carry out several
calls to these operators to define, progressively study of the boundary conditions and/or
loadings.
The operators used differ with the phenomenon:
“MECHANICAL” AFFE_CHAR_CINE
AFFE_CHAR_MECA
data of the type
reality
only
AFFE_CHAR_MECA_F
data of the type
function
“THERMAL” AFFE_CHAR_THER
data of the type
reality
only
AFFE_CHAR_THER_F
data of the type
function
“ACOUSTIC”
AFFE_CHAR_ACOU
data of the type
reality
only
Moreover, one can establish the seismic loading to carry out a calculation of response moving
relative compared to the supports, using the control
CALC_CHAR_SEISME
.
Code_Aster
®
Version
6.4
Titrate:
Great principles of operation of Code_Aster
Date:
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Author (S):
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Key
:
U1.03.00-D
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:
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U1.0- booklet: Synoptic
HT-66/03/002/A
The boundary conditions and loadings can be defined according to their nature:
·
with the nodes,
·
on meshs of edge (edge or face) or meshs support of finite elements, created in
the file mesh. On these meshs the operator
AFFE_MODELE
has affected the types of elements
stop necessary.
For the detailed description of the operands of these operators and the rules of orientation of the meshs
support (total reference mark, local reference mark or unspecified reference mark) one will refer to the documents [U4.44-01],
[U4.44-02], and [U4.44-04].
The boundary conditions can be treated in two ways:
·
by “elimination” of the degrees of freedom imposed (for linear mechanical models
implementing that boundary conditions kinematics (degrees of freedom locked)
without linear relation. One will define in this case the boundary conditions by the control
AFFE_CHAR_CINE
.
·
by dualisation [R3.03.01]. This method because of its greater general information allows
to treat all the types of boundary conditions (degree of freedom imposed, relations linear
between degrees of freedom,…) ; the method used results in adding 2 multipliers of
LAGRANGE for each
ddl
imposed or each linear relation.
Each concept produced by the call to these operators, of type
AFFE_CHAR
, corresponds to a system
boundary conditions and loadings indissociable. In the controls of calculation, one can
to incorporate these concepts while providing for the operands
CHARGE
a list of concepts of this type.
4.3
To carry out calculations by total controls
4.3.1 Analyze
THERMICS
To or not calculate to it (S) field (S) of temperature corresponding to a linear thermal analysis
linear:
·
stationary (moment 0),
·
evolutionary whose moments of calculation are specified by a list of realities defined as a preliminary
The controls to be used are:
·
THER_LINEAIRE
for a linear analysis [U4.54.01],
·
THER_NON_LINE
for a nonlinear analysis [U4.54.02],
·
THER_NON_LINE_MO
for a problem of live loads in steady state
[U4.54.03].
Calculations of the matrices and vectors elementary and assembled necessary to the implementation of
methods of resolution are dealt with by these operators.
4.3.2 Analyze STATIC
To calculate the mechanical evolution of a structure subjected to a list of loadings:
·
MECA_STATIQUE
[U4.51.01]: linear behavior, with superposition of the effects of each
loading,
·
MACRO_ELAS_MULT
[U4.51.02]: linear behavior, by distinguishing the effects of each
loading,
·
STAT_NON_LINE
[U4.51.03]: quasi-static evolution of a structure subjected to a history
of loading in small or great transformations, made of a material of which it
behavior is linear or not linear, with taking into possible account of the contact and
friction.
If this mechanical calculation corresponds to a study of thermo elasticity, one will refer to one moment
thermal calculation already carried out. If the material were defined with characteristics depending on
the temperature, those are interpolated for the temperature corresponding to the moment of calculation
asked.
For the problems of thermohydromecanic coupled, it is the operator
STAT_NON_LINE
who is
used to solve simultaneously the 3 problems thermics, hydraulics and mechanics.
Code_Aster
®
Version
6.4
Titrate:
Great principles of operation of Code_Aster
Date:
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J.M. PROIX, J.R. LEVESQUE
Key
:
U1.03.00-D
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U1.0- booklet: Synoptic
HT-66/03/002/A
Calculations of the matrices and vectors elementary and assembled necessary to the implementation of
methods of resolution are dealt with by these operators.
4.3.3 MODAL analysis
To calculate the clean modes and eigenvalues of the structure (agent to a problem
vibratory or with a problem of buckling).
·
MODE_ITER_SIMULT
[U4.52.03]: calculation of the clean modes by simultaneous iterations;
eigenvalues and vector clean are real or complex,
·
MODE_ITER_INV
[U4.52.04]: calculation of the clean modes by iterations opposite; values
clean and vector clean are real or complex,
·
MACRO_MODE_MECA
[U4.52.02]: reduce the modal analysis while cutting out automatically
the interval of frequency in under intervals,
·
MODE_ITER_CYCL
[U4.52.05]: calculation of the clean modes of a structure with repetitivity
cyclic starting from a base of real clean modes.
These four operators require as a preliminary the calculation of the assembled matrices [U4.61-].
4.3.4 Analyze DYNAMIC
To calculate the dynamic response, linear or not linear, of the structure. Several operators are
available. One can quote for example:
DYNA_LINE_TRAN
[U4.53.02]: temporal dynamic response of a linear structure subjected to one
transitory excitation,
DYNA_LINE_HARM
[U4.53.02]: dynamic response complexes of a linear structure subjected to one
harmonic excitation,
DYNA_TRAN_MODAL
[U4.53.21]: transitory dynamic response in coordinated generalized by
modal recombination.
These three operators require as a preliminary the calculation of the assembled matrices [U4.61-].
DYNA_NON_LINE
[U4.53.01]: temporal dynamic response of a nonlinear structure subjected to
a transitory excitation, which also calculates the assembled matrices.
4.4
results
Results produced by the operators realizing of calculations by finite elements [U4.3-], [U4.4-] and
[U4.5-] are of two main types:
·
maybe of the type of field (by elements or with the nodes) when it acts operators not producing
that only one field (for example
RESO_LDLT
),
·
maybe of the type
RESULT
strictly speaking which gathers assemblies of fields,
accessible by a variable allowing to distinguish them (urgent for a result resulting from one
evolutionary calculation, frequency for a result coming from an algorithm of search for modes
clean or of harmonic answer,…).
A field in a concept of the type
RESULT
is identified:
·
by a variable of access which can be:
-
a simple sequence number referring to the command in which the fields were arranged,
-
a parameter preset according to the type of the concept
RESULT
:
-
frequency or number of mode for one
RESULT
type
mode_meca
,
- moment for one
RESULT
type
evol_elas
,
temper,
dyna_trans
or
evol_noli
.
Code_Aster
®
Version
6.4
Titrate:
Great principles of operation of Code_Aster
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·
by a reference symbol of field referring to the type of the field: displacement, speed,
state of stress, efforts generalized,…
In addition to the variables of access of other parameters can be attached to a type of concept
RESULT
. The contents of these concepts are completely described in the booklet [U5-].
The various fields are built-in in a concept result:
·
maybe by the operator who created the concept, a total control (
MECA_STATIQUE
,
STAT_NON_LINE
,…) or a simple control (
MODE_ITER_SIMULT
,
DYNA_LINE_TRAN
,…),
·
maybe during the execution of a control which makes it possible to add an option of calculation in form
of a field by element (
CALC_ELEM
) or of a field to the nodes (
CALC_NO
); one says then
explicitly that one enriches the concept:
resul
=
operator
(reuse=resu1, RESULT =
resul…) ;
4.5
To exploit the results
The whole of the preceding controls made it possible to build various concepts which are
exploitable, by operators of postprocessing of calculations:
·
general operators of postprocessing (see booklet [U4.81]), for example
CALC_ELEM
,
CALC_NO
,
POST_ELEM
,
POST_RELEVE_T
,
·
operators of breaking process (see booklet [U4.82]), for example
CALC_G_THETA
,
·
metallurgy operator:
CALC_META
,
·
static mechanical postprocessing (see booklet [U4.83]), for example
POST_FATIGUE
,
POST_RCCM
,
·
dynamic mechanical postprocessing (see booklet [U4.84]), for example
POST_DYNA_ALEA
,
POST_DYNA_MODA_T
.
·
operators of extractions:
-
of a field in a concept result
RECU_CHAMP
[U4.63.1],
-
of a field in co-ordinates generalized for a dynamic calculation with modal base
RECU_GENE
[U4.63.2],
- of a function of evolution of a component starting from a concept result
RECU_FONCTION
[U4.63.3],
-
and of restitution of a dynamic response in the physical base
REST_BASE_PHYS
,
-
an operator of postprocessing of functions or tablecloths
CALC_FONCTION
who allows
search of peaks, extremums, combinations linear,… [U4.21.9].
Finally two procedures
IMPR_RESU
[U4.91.01] and
IMPR_COURBE
[U4.33.01] allow the impression and
possibly the creation of exploitable files by other software packages in particular of visualization
graph One will retain in particular graphic visualization by
IDEAS
, GMSH, or GIBI whatever
the tool for mesh used at the beginning.
Code_Aster
®
Version
6.4
Titrate:
Great principles of operation of Code_Aster
Date:
26/06/03
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J.M. PROIX, J.R. LEVESQUE
Key
:
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5
Print files and error messages
Aster writes information relating to calculation in three files whose significance is as follows.
File Contained
ERROR
Errors met during the execution
MESSAGE
Information on the course of calculation.
Repetition of the command file, provided and its interpretation by
Aster.
Execution time of each control.
Messages “system”
RESULT
Only expressly written results requested from the request
of the user and the error messages
Other files are used for the interfaces with the programs of graphic examination.
One distinguishes various types of messages from
ERROR
. The transmitted messages will be only directed
according to their type:
Code
Type of message
Output files
F
fatal error message, the execution stops after various
impressions. The concepts created during the execution are lost.
It is used within the which cannot framework of the serious detection of error
to allow the normal continuation of a control Aster
ERROR
MESSAGE
RESULT
E
error message, the execution continues a little: this type of message
allows to analyze a series of errors before the program stop. (by
example, syntactic analysis of the command file by
Supervisor).
The emission of a message of the type
<E>
is always followed by the emission
of a message of the type <
F>
.
ERROR
MESSAGE
RESULT
S
error message, the concepts created during the execution are
validated by the supervisor, the execution stops with “clean” closing
base
TOTAL
. It is thus reusable in CONTINUATION. It
message makes it possible in particular to be secured against a stop system with
run of an iterative process.
ERROR
MESSAGE
RESULT
With
message of alarm. The number of messages of alarm is limited
automatically with 5 identical successive messages.
It is recommended to the users who have messages of the type
With “to repair” their command file to do them
to disappear
MESSAGE
RESULT
I
message of information of the supervisor
MESSAGE