Code_Aster ®
Version
7.4
Titrate:
Modeling POU_D_EM
Date:
17/06/05
Author (S):
J.L. FLEJOU, F. LEBOUVIER Key
:
U3.11.07-B Page
: 1/6
Organization (S): EDF-R & D/AMA, DeltaCAD
Handbook of Utilization
U3.11 booklet: Mechanical elements of structure 1D
Document: U3.11.07
Modeling POU_D_EM
Summary:
Modeling POU_D_EM corresponds to the formulation of elements of multifibre beam (beam of section
heterogeneous divided into several fibers).
They are usable for three-dimensional problems in linear and nonlinear mechanical analysis.
Handbook of Utilization
U3.11 booklet: Mechanical elements of structure 1D
HT-66/05/004/A
Code_Aster ®
Version
7.4
Titrate:
Modeling POU_D_EM
Date:
17/06/05
Author (S):
J.L. FLEJOU, F. LEBOUVIER Key
:
U3.11.07-B Page
: 2/6
1 Discretization
1.1
Degrees of freedom
For the modeling of multifibre beam into three-dimensional the degrees of freedom of discretization are,
in each node of the mesh support, six components of displacement (three translations and three
rotations). These nodes are supposed to describe a segment of average fiber of the beam.
Finite element
Degrees of freedom (with each node node)
POU_D_EM
DX
DY
DZ
DRX
DRY
DRZ
1.2
Net support of the matrices of rigidity
The meshs support of the finite elements, in displacement formulation, are segments with two nodes
SEG2:
Modeling Nets Element
finished
Remarks
POU_D_EM SEG2
MECA_POU_D_EM
1.3
Net support of the loadings
As for the traditional elements of beam (POU_D_E), all loadings applicable to
elements of multifibre beam are treated by direct discretization on the mesh support of the element in
displacement formulation.
No mesh support of loading is thus necessary for the edge of the elements of beam or
of bar.
1.4
Principal characteristics of modeling
Modeling POU_D_EM is based on the resolution of a problem of beam for which each
definite section is divided into several fibers.
Each fiber behaves then like a beam of Euler, i.e. the sections remain right
and perpendicular to average fiber (assumption of great twinge).
The section can be of an unspecified form.
Handbook of Utilization
U3.11 booklet: Mechanical elements of structure 1D
HT-66/05/004/A
Code_Aster ®
Version
7.4
Titrate:
Modeling POU_D_EM
Date:
17/06/05
Author (S):
J.L. FLEJOU, F. LEBOUVIER Key
:
U3.11.07-B Page
: 3/6
2
Assignment of the characteristics
For this element of structures 1D, it is necessary to affect geometrical characteristics which
are complementary to the data of grid. The definition of these data is carried out with
order AFFE_CARA_ELEM associated with the key words following factors:
· AFFE_SECT
Allows to associate a plane grid of section an element beam.
· AFFE_FIBER
Allows to associate a section made up of one or more specific fibers an element
beam.
· POUTRE
Allows to associate a geometrical characteristic of torsion an element beam.
· ORIENTATION
Allows “to turn” the plane grid of the section around the axis of the beam.
Remarks on the characteristics of modeling:
1) Within the framework of modeling of a multifibre type, there are two “levels” of modeling. It
y with the modeling known as “longitudinal” which will be represented by a beam (support
geometrical SEG2) and a modeling planes section (perpendicular to the SEG2).
Operand AFFE_SECT makes it possible to associate a plane grid of section an element beam.
Operand AFFE_FIBER makes it possible to associate a section made up of one or more
specific fibers (defined by their position and surfaces) with an element beam.
2) In general in the plane modeling of the section, several materials cohabit. By
example, in a section concrete reinforced, there are at the same time concrete and reinforcements. In it
case there, operator CREA_MAILLAGE makes it possible to duplicate support E.F so that there is not
that only one material by support.
3) The operand
POUTRE is used to affect a geometrical characteristic of torsion (JX)
who cannot be calculated starting from the plane grid of the section. If the value is used
GENERALE for key word SECTION of operand POUTRE, it is necessary to give the characteristics
(CARA) With, IY and IZ in addition to JX because operator AFFE_CARA_ELEM waits at least these
four characteristics for a traditional beam.
Values (VALE) data with A, IY and IZ are not used by element POU_D_EM, because
they are calculated starting from the plane grid of the section. On the other hand a checking of
coherence of the information (AIRE and INERTIE) provided on the one hand by A, IY, IZ and of other
leaves by key words AFFE_SECT and AFFE_FIBER is carried out. The criterion of error is based
on the error relating and is compared either with the default value or to that given by
the user via key words PREC_AIRE and PREC_INERTIE. (Cf orders
AFFE_CARA_ELEM key words PREC_AIRE and PREC_INERTIE of operand POUTRE).
4) The operand
ORIENTATION is used in general “to turn” the plane grid of the section
around the axis of beam (CARA “ANGL_VRIL”). Indeed, by defect, axis X (horizontal)
plane grid of the section is confused with the axis there beam (see [Figure 3-a]).
Handbook of Utilization
U3.11 booklet: Mechanical elements of structure 1D
HT-66/05/004/A
Code_Aster ®
Version
7.4
Titrate:
Modeling POU_D_EM
Date:
17/06/05
Author (S):
J.L. FLEJOU, F. LEBOUVIER Key
:
U3.11.07-B Page
: 4/6
Y
p
y
X
X
p
Z
p
Element beam
Grid section
Appear 3-a: Orientation by defect of the plane grid compared to the element beam
3 Loadings
supported
The loadings available are as follows:
· “FORCE_POUTRE”
Allows to apply linear forces.
· “PESANTEUR”
Allows to apply a loading of the gravity type.
· “ROTATION”
Allows to define the disk speed and the vector of rotation.
· “TEMP_CALCULEE”
Allows to apply a thermal loading.
4 Possibilities
non-linear
4.1
Law of behaviors
Laws of behaviors specific to this modeling, usable under COMP_INCR in
STAT_NON_LINE and DYNA_NON_LINE are as follows (Cf. [U4.51.11]):
/“CORR_ACIER”
/“LABORD_1D'
/“PINTO_MENEGOTTO”
/“VMIS_CINE_LINE”
/“VMIS_ISOT_LINE”
/“VMIS_ISOT_TRAC”
/“GRAN_IRRA_LOG”
Moreover, it is possible for this modeling, which uses a monodimensional state of stresses
to use the behaviors 3D by using key word ALGO_1D (METHODE = DEBORST).
4.2 Deformations
Only the linearized deformations key word “PETIT” under DEFORMATION are available in
relations of behavior (Cf. [U4.51.11]).
Handbook of Utilization
U3.11 booklet: Mechanical elements of structure 1D
HT-66/05/004/A
Code_Aster ®
Version
7.4
Titrate:
Modeling POU_D_EM
Date:
17/06/05
Author (S):
J.L. FLEJOU, F. LEBOUVIER Key
:
U3.11.07-B Page
: 5/6
5
Examples of implementation: case-tests
· Linear statics
SSLL111A [V3.01.111]: Static response of a concrete beam reinforced (section in T) with one
linear behavior subjected to three successive loading cases: a specific force, the weight
clean and a rise in temperature.
· Non-linear statics
SSNL119A [V6.02.119]: Deflection test 3 points, static response of a reinforced concrete beam
(rectangular section) with a nonlinear behavior of Borderie.
· Linear dynamics
SDLL130B [V2.02.130]: Seismic response of a reinforced concrete beam (rectangular section) to
linear behavior.
· Non-linear dynamics
SDNL130A [V5.02.130]: Seismic response of a reinforced concrete beam (rectangular section) to
nonlinear behavior.
Handbook of Utilization
U3.11 booklet: Mechanical elements of structure 1D
HT-66/05/004/A
Code_Aster ®
Version
7.4
Titrate:
Modeling POU_D_EM
Date:
17/06/05
Author (S):
J.L. FLEJOU, F. LEBOUVIER Key
:
U3.11.07-B Page
: 6/6
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Handbook of Utilization
U3.11 booklet: Mechanical elements of structure 1D
HT-66/05/004/A
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