Code_Aster ®
Version
7.4
Titrate:
Modeling 2d_DIS_T and 2d_DIS_TR


Date:
03/06/05
Author (S):
J.M. PROIX, F. LEBOUVIER Key
:
U3.13.09-C Page
: 1/4

Organization (S): EDF-R & D/AMA, DeltaCAD
Handbook of Utilization
U3.13 booklet: Mechanical finite elements 2D
Document: U3.13.09
Modelings 2d_DIS_T and 2d_DIS_TR

Summary:

This document describes for modelings 2d_DIS_T, 2d_DIS_TR (cf [R5.03.17]):

· degrees of freedom carried by the finite elements which support modeling,
· the related meshs supports,
· supported loadings,
· nonlinear possibilities,
· case-tests implementing modelings.

Modeling 2d_DIS_T allows the representation of discrete elements of translation one or two nodes.
Modeling 2d_DIS_TR allows the representation of discrete elements of translation and rotation one or
two nodes.

They are usable for two-dimensional problems in linear mechanical analysis or not linear.
Handbook of Utilization
U3.13 booklet: Mechanical finite elements 2D
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Modeling 2d_DIS_T and 2d_DIS_TR


Date:
03/06/05
Author (S):
J.M. PROIX, F. LEBOUVIER Key
:
U3.13.09-C Page
: 2/4

1 Discretization

1.1
Degrees of freedom

The degrees of freedom of discretization are, in each node of the mesh support, both
components of displacement of translation and rotation.

Finite element
Degrees of freedom (with each node node)
2d_DIS_T
DX
DY




2d_DIS_TR
DX
DY
DRZ




1.2
Net support of the matrices of rigidity

The meshs support of the discrete elements, in displacement formulation, are segments with two
nodes SEG2 or of specific meshs POI1 confused with a node:

Modeling Nets Element
finished
Remarks
2d_DIS_T POI1
MECA_2D_DIS_T_N

SEG2
MECA_2D_DIS_T_L

2d_DIS_TR POI1
MECA_2D_DIS_TR_N

SEG2
MECA_2D_DIS_TR_L


With regard to meshs POI1, the efforts intern are calculated starting from the differences of
degrees of freedom of the mesh with the reference mark fixes (as if this discrete node were attached to a reference mark
fixed).
For meshs SEG2, the efforts are calculated starting from the differences of the degrees of freedom carried by
each of the 2 nodes.

2
Assignment of the characteristics

For these discrete elements, 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:

· DISCRET
Allows to define and affect the values of the matrices of rigidity, mass or damping.
Supported modelings: 2d_DIS_T, 2d_DIS_TR

· ORIENTATION
Allows to define and affect a local reference mark.
Supported modelings: 2d_DIS_T, 2d_DIS_TR
Handbook of Utilization
U3.13 booklet: Mechanical finite elements 2D
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Modeling 2d_DIS_T and 2d_DIS_TR


Date:
03/06/05
Author (S):
J.M. PROIX, F. LEBOUVIER Key
:
U3.13.09-C Page
: 3/4

3 Loadings
supported

The supported loading is as follows:

· “PESANTEUR”
Allows to apply a loading of the gravity type.
Supported modelings: 2d_DIS_T, 2d_DIS_TR

4
Possibilities not - linear

Only modeling 2d_DIS_T being pressed on a mesh with 2 nodes is usable with
STAT_NON_LINE and DYNA_NON_LINE. It is only in this case that one uses DEFI_MATERIAU.

4.1
Law of behavior

Laws of behaviors specific to these modelings, usable under COMP_INCR in
STAT_NON_LINE and DYNA_NON_LINE the following ones (Cf. [U4.51.11]):

/“DIS_GOUJ 2e_ELAS”
Supported modeling: 2d_DIS_T (Maille SEG2)

/“DIS_GOUJ 2e_PLAS”
Supported modeling: 2d_DIS_T (Maille SEG2)

/“ELAS”
Supported modelings: 2d_DIS_T, 2d_DIS_TR

In addition to the assignment of characteristics (AFFE_CARA_ELEM) the use of modelings DIS_T
and DIS_TR with STAT_NON_LINE/DYNA_NON_LINE/DYNA_TRAN_EXPLI implies to define
characteristics material (AFFE_MATERIAU).

4.2 Deformations

Deformations available, used in the relations of behavior under the key word
DEFORMATION for operators STAT_NON_LINE and DYNA_NON_LINE are (Cf. [U4.51.11]):

/“PETIT”
The deformations used for the relation of behavior are the linearized deformations
calculated on the initial geometry.
Supported modeling: 2d_DIS_TR (Maille SEG2)

/“PETIT_REAC”
The deformations used in the incremental relation of behavior are the deformations
linearized calculated on the reactualized geometry.
Supported modeling: 2d_DIS_TR (Maille SEG2)
Handbook of Utilization
U3.13 booklet: Mechanical finite elements 2D
HT-66/05/004/A

Code_Aster ®
Version
7.4
Titrate:
Modeling 2d_DIS_T and 2d_DIS_TR


Date:
03/06/05
Author (S):
J.M. PROIX, F. LEBOUVIER Key
:
U3.13.09-C Page
: 4/4

5
Examples of implementation: case-tests

· 2d_DIS_T
­ Statique
linear
SSLL108A [V3.01.108]: Analyze response of a bar, modelled by 10 elements
discrete (Mailles SEG2) subjected to a loading of traction.
­ Statique
non-linear
ZZZZ120A: Calcul of an assembly Pin-Bride without top of support, with a law of
elastoplastic behavior of Von Mises representing the local behavior of a net of
pin of threaded assembly.
­ Dynamique
linear
SDLD02E [V2.01.002]: Seek frequencies of vibration and modes associated with one
mechanical structure made up of masses and springs.
­ Dynamique
non-linear
Rubbing dynamic SDNV104A: Réponse of a rigid shoe subjected to a pressure and one
force of recall.

· 2d_DIS_TR
­ Dynamique
linear
SDLD02F [V2.01.002]: Seek frequencies of vibration and modes associated with one
mechanical structure made up of masses and springs.

Handbook of Utilization
U3.13 booklet: Mechanical finite elements 2D
HT-66/05/004/A

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