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Great principles of operation of Code_Aster
Date:
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:
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Organization (S): EDF-R & D/AMA
Handbook of Utilization
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 principal rules
of use.
This document remains a general description and the reader will refer usefully to the other documents, for all
details of use.
Handbook of Utilization
U1.0- booklet: Synoptic
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Code_Aster ®
Version
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Titrate:
Great principles of operation of Code_Aster
Date:
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Author (S):
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:
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1 Principles
Generals
Version 6 of 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 grid and visualization
graph, which does not form part of Code. However, several tools are usable for these
operations via procedures of interface integrated into Code.
To make a study, the user must, in general, prepare two data files:
· the file of grid:
to define geometrical and topological description grid without choosing, at this stage the type
of formulation of the finite elements used or the physical phenomenon to model. Some
studies can result in using several files of grid.
This file of grid, in general, is produced by an interface integrated into Code Aster to leave
of a file coming from a software of grid used out of preprocessor (GIBI, GMSH, IDEAS…).
Information which this file must contain is specific to Code_Aster. They define
traditional 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 grid, 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 command which allows:
-
of reading and if required enriching the data of the file by grid (or other sources of
external results),
-
to affect the data of modeling on the entities of the grid,
-
to connect various operations of processing: specific calculations, postprocessings,
-
to publish the results on various files.
The text of command refers to the names of geometrical entities defined in the file of
grid. It also makes it possible to define new groups constantly.
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From the data-processing point of view, these two files are files ASCII in free format. One gives some here
principal characteristics:
Syntax of the file of grid:
· 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 Python language, allowing to include instructions of this language
· character # indicates the beginning, until the end of the line, of a comment.
· The commands 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 Grid
2.1 General
The structure and the syntax of the file of grid are detailed in Fascicule [U3.01.00].
This file can be written (for elementary grids) 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 grid
products by other software packages (IDEAS, GIBI, GMSH…) or of the files of grid to format MED.
2.2
The file of Aster grid
The file of Aster grid is read first line until the first occurrence of a line
begin with word FIN. This key word is obligatory. The file of grid 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 grid 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 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
grid:
· 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 constraint becomes bearable when one uses an interface, which does the work from
indications provided at the time it grid (see 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 principal 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 to 3, 6 or 7 nodes
/QUAD4/QUAD8/QUAD9 quadrangles to 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 to 4 or 10 nodes
/
PYRAM5
/
PYRAM13 pyramids to 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 Aster grid.
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 grid with the format
of exchange MED.
2.4.1 Universal file IDEAS
The interface is made using command PRE_IDEAS [U7.01.01]
The convertible file is the universal file defined by documentation I-DEAS (see Fascicule
[U3.03.01]). The recognition 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 grid GIBI
The interface is made using command PRE_GIBI [U7.01.11]).
The convertible file is file ASCII restored by command SAUVER FORMAT of CASTEM 2000.
The precise description of the interface is given in [U3.04.01].
2.4.3 The file of grid GMSH
The interface is made using command PRE_GMSH [U7.01.31]).
The convertible file is file ASCII restored by command SAVE of GMSH.
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2.4.4 The file of grid to format MED
The interface is made using command LIRE_MAILLAGE (FORMAT:“MED”) [U4.21.01]).
MED (Modélisation and Echanges de Données) 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. The reading of a file MED by LIRE_MAILLAGE, makes it possible to recover a grid
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 grids and results between ASTER
and the tool of refinement of grid HOMARD. The precise description of the interface is given in
[U7.01.21].
2.5
The use of incompatible grids
Although the finite element method recommends the use of regular grids, without
discontinuity, to obtain a correct convergence towards the solution of the continuous problem, it can be
necessary for certain modelings to use incompatible grids: on both sides
of a border, the grids do not correspond. The connection of these two grids is
then managed on the level of the command file by key word LIAISON_MAIL of the command
AFFE_CHAR_MECA. This makes it possible in particular to finely connect a zone with a grid with another
zone where one can be satisfied with a coarse grid.
2.6
Adaptive grid
Starting from an initial grid, it is possible to adapt the grid, to minimize the made error, with
assistance of the macro command MACR_ADAP_MAIL, which calls upon software HOMARD. Software of
adaptive grid HOMARD functions on grids made of segments, triangles, tetrahedrons.
This adaptation of grid 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, software HOMARD will modify it
grid. It is also possible to interpolate fields of temperature or displacement with
nodes of the old grid towards the new one [U7.03.01].
3 Commands
3.1
The command file
The command file contains a whole of commands, 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 commands 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 commands.
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
DEBUT () or with procedure POURSUITE (), and until the first occurrence of the command
FIN (). The commands located before DEBUT () or POURSUITE () and after FIN () are not
carried out, but must be syntactically correct).
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· Syntactic phase of checking:
-
reading and syntactic checking of each command; 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 Code like a succession of commands
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 commands and its implications on the drafting of the command file
are detailed in the booklet [U1.03.01]. Here an example of some commands is given
(extracted the example with accompanying notes in [U1.05.00]):
mall = LIRE_MAILLAGE ()
mod1 = AFFE_MODELE (MAILLAGE = 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 (MODELE = mod1
PRES_REP =_F (GROUP_MA = (“lfa”, “ldf”),
PRES = f_y))
.....
res1 = MECA_STATIQUE (MODELE=mod1,
......
EXCIT=_F (CHARGE = charg),
….)
res1 = CALC_ELEM (reuse=res1, RESULTAT=res1,
...........
MODELE=mod1,
OPTION= (“SIGM_ELNO_DEPL”, “EPSI_ELNO_DEPL”))
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Some general points will be noted, which one can observe on the preceding example:
· any command starts in first column,
· the list of the operands of a command is obligatorily between brackets, as well as the lists
elements,
· a nom_de_concept can appear only only once in the text of command 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),
command 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 a 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 mot_clé last 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 assigning material MAT1 to all the meshs.
· One assigns then material MAT2 to the group of meshs mail2 which contains, the meshs m8, m9
and m10.
· One assigns finally material MAT3 to the group of meshs mail1 (m5, m6 and m7) and to the meshs
m7 and m8, which causes conflict since the mesh m7 forms already part of the mail1 group.
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. This one deals with the space management
memory asked by the user at the time of the request for execution (Mémoire parameter 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. This one can
to be regarded as a data base, since it contains, at the end of the execution the repertory
(names and attributes) which makes it possible to exploit all the segments of values that it contains.
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Code_Aster uses several data bases:
· the data base GLOBALE, which 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 Superviseur 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 commands:
· procedures to exchange files with the external world,
· operators to create concepts progressively produces course of operation
of modeling and calculation.
The commands 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 command, if it stopped
prematurely (lack of time, incomplete or incorrect data detected in phase
of execution,…).
Beginning
order 1
order 1
order 2
order 2
·
·
·
·
Study
order I
order I
Study
End
order i+1
Continuation
order i+1
·
·
·
·
order J
order J
End
order j+1
Continuation
order j+1
The continuation is not possible
·
·
that within the framework of one
·
·
even version
order N
order N
End
To manage these possibilities, it will be noted that three commands play a paramount part. They are those
who correspond to the procedures which activate the supervisor:
· DEBUT ()
obligatory for the first execution of a study,
· POURSUITE ()
obligatory starting from the second execution of a study,
· FIN ()
obligatory for all the executions.
For a given study, one can subject command files having the following structure:
Note:
· Command INCLUDE makes it possible to include in a flood of commands the contents of another
command file. This allows in particular, to preserve a file of the commands
principal 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 commands 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 (TYPE = [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) """))
will cara = AFFE_CARA_ELEM (MODELE = model
POUTRE =_F (GROUP_MA = all, SECTION: “CERCLE”,
CARA = (“R”, “EP”), VALE = (Rext, EPtub)))
These possibilities result in a simple substitution of the values each time Superviseur
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 command, LIRE_FONCTION.
· that is to say defined in the command file by:
-
DEFI_CONSTANTE produces a concept function with only one constant value,
-
DEFI_FONCTION produces a concept function for a size function of one
real parameter,
-
DEFI_NAPPE produces 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 function type and can only be used
as argument of operands which accept this type. The operators who accept one
argument of the function type 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 operator FORMULE: 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',)
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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 of 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
commands, by proposing for each command the list of the possible key words while checking
automatically syntax, and by giving access to the documentation of Manuel of use
(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 grid,
· 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 commands 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 grid
One will not reconsider here the possible fragmentation of the command file, which was presented
in a preceding paragraph.
The first executable command is:
DEBUT
()
The argument of this command are useful only for the maintenance actions or in
case of very large studies.
For the reading of the grid, coming from a software of external grid, 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:
DEBUT
()
PRE_IDEAS ()
FIN ()
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the normal study will be able to then begin for example by:
DEBUT
()
my = LIRE_MAILLAGE
()
· to convert the file right before reading it:
DEBUT
()
PRE_IDEAS
()
my = LIRE_MAILLAGE
()
4.2
To assign data of modeling to the grid
To build the modeling of a mechanical problem, thermal or acoustic, it is
essential to assign to the topological entities grid:
· 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 grid. Five key words are usable for
that, according to the specification of the operator:
· to refer to all the grid 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], who can be called several times on
even grid. It uses the rules of overload and remanence.
Note:
For a study with several treated phenomena (“MECANIQUE”, “THERMIQUE”), 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-].
Handbook of Utilization
U1.0- booklet: Synoptic
HT-66/03/002/A
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
:
U1.03.00-D Page
: 12/16
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 are used to define a material field by association of the grid. 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 grid 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]), who uses, for
to simplify the drafting of the command, 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 nodes) or
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 which 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 given of real type only
AFFE_CHAR_MECA_F
data of the function type
“THERMIQUE” AFFE_CHAR_THER given of real type only
AFFE_CHAR_THER_F
data of the function type
“ACOUSTIQUE”
AFFE_CHAR_ACOU given of real type only
Moreover, one can establish the seismic loading to carry out a calculation of response moving
relative compared to the supports, using command CALC_CHAR_SEISME.
Handbook of Utilization
U1.0- booklet: Synoptic
HT-66/03/002/A
Code_Aster ®
Version
6.4
Titrate:
Great principles of operation of Code_Aster
Date:
26/06/03
Author (S):
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:
U1.03.00-D Page
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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 grid. On these meshs 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 blocked)
without linear relation. One will define in this case the boundary conditions by the command
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 commands of calculation, one can
to incorporate these concepts by providing for operands CHARGE a list of concepts of this type.
4.3
To carry out calculations by total commands
4.3.1 Analyze
THERMIQUE
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 commands 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.
Handbook of Utilization
U1.0- booklet: Synoptic
HT-66/03/002/A
Code_Aster ®
Version
6.4
Titrate:
Great principles of operation of Code_Aster
Date:
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Author (S):
J.M. PROIX, J.R. LEVESQUE Key
:
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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 (correspondent 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 principal 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 RESULTAT strictly speaking which gathers sets 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 RESULTAT is located:
· 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 concept RESULTAT:
-
frequency or number of mode for a RESULTAT of the mode_meca type,
- moment for a RESULTAT of the evol_elas type, temper, dyna_trans or
evol_noli.
Handbook of Utilization
U1.0- booklet: Synoptic
HT-66/03/002/A
Code_Aster ®
Version
6.4
Titrate:
Great principles of operation of Code_Aster
Date:
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Author (S):
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:
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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
RESULTAT. 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 command (MECA_STATIQUE,
STAT_NON_LINE,…) or a simple command (MODE_ITER_SIMULT,
DYNA_LINE_TRAN,…),
· maybe during the execution of a command which makes it possible to add an option of calculation in form
of a field by element (CALC_ELEM) or of a field to nodes (CALC_NO); one says then
explicitly that one enriches the concept:
resul
=
operator
(reuse=resu1, RESULTAT =
resul…) ;
4.5
To exploit the results
The whole of the preceding commands 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 physical base REST_BASE_PHYS,
-
an operator of postprocessing of functions or tablecloths CALC_FONCTION which 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 grid used at the beginning.
Handbook of Utilization
U1.0- booklet: Synoptic
HT-66/03/002/A
Code_Aster ®
Version
6.4
Titrate:
Great principles of operation of Code_Aster
Date:
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:
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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
ERREUR
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 command.
Messages “system”
RESULTAT
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 error messages. 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 ERREUR
impressions. The concepts created during the execution are lost. MESSAGE
It is used within the framework of the serious detection of error which cannot RESULTAT
to allow the normal continuation of a Aster command
E
error message, the execution continues a little: this type of message ERREUR
allows to analyze a series of errors before the program stop. (by MESSAGE
example, syntactic analysis of the command file by the RESULTAT
Supervisor).
The emission of a message of the <E> type is always followed by the emission
of a message of the <F> type.
S
error message, the concepts created during the execution are ERREUR
validated by the supervisor, the execution stops with “clean” closing MESSAGE
base GLOBALE. It is thus reusable in POURSUITE. This RESULT
message makes it possible in particular to be secured against a stop system with
run of an iterative process.
With
message of alarm. The number of messages of alarm is limited MESSAGE
automatically with 5 identical successive messages.
RESULTAT
It is recommended to the users who have messages of the type
With “to repair” their command file to do them
to disappear
I
message of information of the supervisor
MESSAGE
Handbook of Utilization
U1.0- booklet: Synoptic
HT-66/03/002/A
Outline document