Code_Aster ®
Version
7.4
Titrate:
Modelings DKT - DST - Q4G
Date:
01/06/05
Author (S):
X. DESROCHES, F. LEBOUVIER Key
:
U3.12.01-D Page
: 1/6
Organization (S): EDF-R & D/AMA, DeltaCAD
Handbook of Utilization
U3.12 booklet: Mechanical elements of structure 2D
Document: U3.12.01
Modelings DKT - DST - Q4G
Summary:
This document describes for modelings DKT - DST - Q4G:
· degrees of freedom carried by the finite elements which support modeling,
· the related meshs supports,
· supported loadings,
· nonlinear possibilities,
· case-tests implementing modelings.
They are usable for problems of plate into three-dimensional [R3.07.03] in mechanical analysis
linear for all modelings and in nonlinear material for modeling DKT only. Their
use for problems of hull is usually allowed by considering that the plan of the element is
comparable to a tangent facet with the average layer of the hull (attention, only the plane facets are
allowed).
Thermomechanical calculations are chained starting from the finite elements of thermal hulls (see [U3.22.01]).
Handbook of Utilization
U3.12 booklet: Mechanical elements of structure 2D
HT-66/05/004/A
Code_Aster ®
Version
7.4
Titrate:
Modelings DKT - DST - Q4G
Date:
01/06/05
Author (S):
X. DESROCHES, F. LEBOUVIER Key
:
U3.12.01-D Page
: 2/6
1 Discretization
1.1
Degrees of freedom
For three modelings of plate 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) with the nodes nodes of the mesh support. These nodes are supposed to describe a facet
tangent with the average layer of the hull.
Finite element
Degrees of freedom (with each node node)
DKT/DKQ
DX
DY
DZ
DRX
DRY
DRZ
DST/DSQ
DX
DY
DZ
DRX
DRY
DRZ
Q4G (Q4)
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, can be triangles or
quadrangles. In this last case, the meshs are supposed to be plane (4 nodes nodes
coplanar):
Modeling Nets Element
finished
Remarks
DKT TRIA3
MEDKTR3
QUAD4
MEDKQU4
DST TRIA3
MEDSTR3
QUAD4
MEDSQU4
Q4G (Q4)
QUAD4 MEQ4QU4
1.3
Net support of the loadings
All the loadings applicable to the facets of the elements of plate are treated by discretization
direct on the mesh support of the element in displacement formulation.
No mesh support of loading is thus necessary for the faces of the elements of plates.
For the applicable loadings on the edges of the elements of plate, a mesh support of the type
SEG2 is usable:
Modeling Nets Element
finished
Remarks
DKT SEG2
MEBODKT
DST SEG2
MEBODST
Q4G (Q4)
SEG2 MEBOQ4G
Handbook of Utilization
U3.12 booklet: Mechanical elements of structure 2D
HT-66/05/004/A
Code_Aster ®
Version
7.4
Titrate:
Modelings DKT - DST - Q4G
Date:
01/06/05
Author (S):
X. DESROCHES, F. LEBOUVIER Key
:
U3.12.01-D Page
: 3/6
2
Assignment of the characteristics
For these elements of plate or hulls, it is necessary to affect characteristics
geometrical which is complementary to the data of grid. The definition of these data is
carried out with command AFFE_CARA_ELEM associated with the key word following factor:
· COQUE
Allows to define and affect on the meshs, the thickness, the coefficient of shearing,
offsetting,…
For the study of structures comprising of multi-layer materials it is necessary to affect them
characteristics of each layer (thickness, type of material) and their stacking
(orientation of fibers). The definition of these data is carried out with the command
DEFI_COQU_MULT.
3 Loadings
supported
The loadings available are as follows:
· FORCE_ARETE
Allows to apply linear forces.
Supported modelings: DKT, DST, Q4G
· FORCE_COQUE
Allows to apply surface efforts.
Supported modelings: DKT, DST, Q4G
· PESANTEUR
Allows to define the acceleration and the direction of gravity.
Supported modelings: DKT, DST, Q4G
· PRES_REP
Allows to apply surface efforts.
Supported modelings: DKT, DST, Q4G
· TEMP_CALCULEE
Allows to apply a thermal loading of origin.
Supported modelings: DKT, DST, Q4G
· EPSI_INIT
Allows to apply a loading of initial deformation.
Supported modelings: DKT, DST, Q4G
Handbook of Utilization
U3.12 booklet: Mechanical elements of structure 2D
HT-66/05/004/A
Code_Aster ®
Version
7.4
Titrate:
Modelings DKT - DST - Q4G
Date:
01/06/05
Author (S):
X. DESROCHES, F. LEBOUVIER Key
:
U3.12.01-D Page
: 4/6
4 Possibilities
non-linear
For modeling DKT only.
4.1
Law of behaviors
Only modeling “DKT” has non-linear possibilities. Laws of behaviors
specific to this modeling, usable under COMP_INCR in STAT_NON_LINE and
DYNA_NON_LINE are the relations of behavior in plane constraints available with
modelings “AXIS” and “C_PLAN”. These relations are to be used with the key word
ALGO_C_PLAN = ' DEBORST '' (cf [U4.51.11]).
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 deformations
linearized.
/“PETIT_REAC”
The increments of deformations used in the incremental relation of behavior are
linearized deformations of the increment of displacement in the reactualized geometry.
Note:
Attention, the calculation of the deformations using PETIT_REAC is only one approximation of
assumptions of great displacements. It requires to carry out very small increments of
loading. To correctly take into account great displacements, and especially them
great rotations, it is recommended to use modeling COQUE_3D, with
DEFORMATION=' GREEN_GR'.
5
List cases tests available
· DKT
Statique
linear
FORMA01B [V7.15.100]: Analyze of a piping comprising an elbow subjected to one
specific force and with an internal pressure.
SSLS100A [V3.03.100]: Plate circular embedded on its contour, subjected to one
uniform pressure, with a normal force and its actual weight.
Statique
non-linear
SSNL501C [V6.02.501]: Quasi-static analysis of a beam fixed to both
ends, subjected to a uniform pressure, with an elastic material perfectly
plastic.
Dynamique
linear
SDLS03C: Seek Eigen frequencies and modes associated with a plate
rectangular thin in simple support on its edges.
Dynamique
non-linear
ELSA01D: Non-linear dynamic response of a piping in the shape of quadrant (elsa)
subjected to a seismic loading.
Handbook of Utilization
U3.12 booklet: Mechanical elements of structure 2D
HT-66/05/004/A
Code_Aster ®
Version
7.4
Titrate:
Modelings DKT - DST - Q4G
Date:
01/06/05
Author (S):
X. DESROCHES, F. LEBOUVIER Key
:
U3.12.01-D Page
: 5/6
· DST
Statique
linear
SSLS101F [V3.03.101]: Plate circular posed on the edge, subjected 3 loadings:
actual weight, pressure and effort distributed constant.
HSLS01A [V7.11.001]: Analyze of a thin square plate embedded on its contour
subjected to a heat gradient in the thickness.
Dynamique
linear
SDLS03A: Recherche of the Eigen frequencies and the modes associated with a plate
rectangular thin in simple support on its edges.
· Q4G
Statique
linear
SSLS101H [V3.03.101]: Plate circular posed on the edge under 3 loadings: weight
clean, pressure and effort distributed constant.
HSLS01B [V7.11.001]: Analyze of a thin square plate embedded on its contour
subjected to a heat gradient in the thickness.
Dynamique
linear
SDLS03B: Recherche of the Eigen frequencies and the modes associated with a plate
rectangular thin in simple support on its edges.
Handbook of Utilization
U3.12 booklet: Mechanical elements of structure 2D
HT-66/05/004/A
Code_Aster ®
Version
7.4
Titrate:
Modelings DKT - DST - Q4G
Date:
01/06/05
Author (S):
X. DESROCHES, F. LEBOUVIER Key
:
U3.12.01-D Page
: 6/6
Intentionally white left page.
Handbook of Utilization
U3.12 booklet: Mechanical elements of structure 2D
HT-66/05/004/A
Outline document