ProductsAbaqus/StandardAbaqus/ExplicitAbaqus/CAE TypeModel data LevelPartPart instance Abaqus/CAEProperty module Required parameters- ELSET
Set this parameter equal to the name of the element set containing the shell
elements for which the section behavior is being defined.
Required parameter in
Abaqus/Explicit,
optional parameter in
Abaqus/Standard- DENSITY
Set this parameter equal to the mass per unit surface area of the shell.
If the MATERIAL and COMPOSITE parameters are omitted, this density accounts for the mass of
the shell, since no material definition is given.
If the MATERIAL or COMPOSITE parameter is used, the mass of the shell includes a
contribution from this parameter in addition to any contribution from the
material definition.
Optional parameters- BENDING ONLY
Include this parameter to ignore membrane stiffness effects in the shell.
Bending stiffness and transverse shear stiffness coefficients are computed
normally. Membrane-bending coupling coefficients are set to zero. Diagonal
membrane stiffness coefficients are set to 1 × 10−6 times the
largest diagonal bending stiffness term. Off-diagonal membrane stiffness
coefficients are set to zero.
- CONTROLS
In an
Abaqus/Explicit
analysis, set this parameter equal to the name of a section controls definition
(see
Section controls)
to be used to specify the second-order accurate element formulation option, a
nondefault hourglass control formulation option, or scale factors.
In an
Abaqus/Standard
analysis, set this parameter equal to the name of a section controls definition
to be used to specify the enhanced hourglass control formulation (see
Section controls)
or to be used in a subsequent
Abaqus/Explicit
import analysis.
- LAYUP
This parameter is relevant only when the COMPOSITE parameter is used.
Set this parameter equal to the name of a composite layup (see
Composite layups).
Abaqus/CAE
uses this name to identify the composite layup that contains the shell section.
- MEMBRANE ONLY
Include this parameter to ignore bending stiffness effects in the shell.
Membrane stiffness and transverse shear stiffness coefficients are computed
normally. Membrane-bending coupling coefficients are set to zero. Diagonal
bending stiffness coefficients are set to 1 × 10−6 times the largest
diagonal membrane stiffness term. Off-diagonal bending stiffness coefficients
are set to zero.
- OFFSET
Include this parameter to define the distance (as a fraction of the shell
thickness) from the shell midsurface to the reference surface (containing the
nodes of the element). This parameter accepts positive or negative values, the
labels SPOS or
SNEG, or in an
Abaqus/Standard
analysis the name of a distribution (see
Distribution definition).
Positive values of the offset are in the positive normal direction (see
About shell elements).
When OFFSET=0.5 (or SPOS), the top surface
of the shell is the reference surface. When OFFSET=−0.5 (or SNEG), the bottom
surface of the shell is the reference surface. The default is OFFSET=0, which indicates that the middle surface of the shell is the
reference surface.
In an
Abaqus/Standard
analysis a spatially varying offset can be specified by setting OFFSET equal to the name of a distribution. The distribution used to
define the shell offset must have a default value. The default offset is used
by any shell element assigned to the shell section that is not specifically
assigned a value in the distribution.
- ORIENTATION
Set this parameter equal to the name of an orientation definition (see
Orientations)
to be used with the section forces and section strains.
- POISSON
Include this parameter to define the shell thickness direction behavior.
Set this parameter equal to a nonzero value to cause the thickness direction
strain under plane stress conditions to be a linear function of the membrane
strains. The value of the POISSON parameter must be between −1.0 and 0.5.
Set POISSON=ELASTIC to automatically select this parameter value based on the
initial isotropic elastic part of the material definition.
The default is POISSON=0.5.
- SMEAR ALL LAYERS
This parameter is relevant only when the COMPOSITE parameter is used.
Include this parameter to ignore the material layer stacking sequence.
Transverse shear stiffness coefficients are computed normally. Membrane-bending
coupling terms are set to zero, and bending stiffness terms are computed as
T2/12 times the corresponding membrane
stiffness terms, where T is the total thickness of the
shell.
- STACK DIRECTION
This parameter is relevant only for continuum shells.
Set this parameter equal to 1, 2, 3, or ORIENTATION to define the continuum shell stack or thickness direction.
Specify one of the numerical values to select the corresponding isoparametric
direction of the element as the stack or thickness direction. The default is STACK DIRECTION=3.
If STACK DIRECTION=ORIENTATION, the ORIENTATION parameter is also required.
To obtain a desired thickness direction, the appropriate numerical value for
the STACK DIRECTION parameter depends on the element connectivity. For a
mesh-independent specification, use STACK DIRECTION=ORIENTATION. If the orientation assigned to the ORIENTATION parameter is defined with a distribution (Distribution definition),
STACK DIRECTION=ORIENTATION is not supported.
- SYMMETRIC
This parameter is relevant only when the COMPOSITE parameter is used.
Include this parameter if the layers in the composite shell are symmetric
about a central core. This parameter cannot be used if a spatially varying
thickness or orientation angle is defined on any composite layer using a
distribution (Distribution definition).
- THICKNESS MODULUS
This parameter is relevant only for continuum shells.
Set this parameter equal to an effective thickness modulus. The default
effective thickness modulus is twice the initial in-plane shear modulus based
on the material definition.
- ZERO
If the section is defined by its general stiffness, set this parameter equal
to ,
the reference temperature for thermal expansion (for example, ZERO=50 means
).
This parameter is ignored if the COMPOSITE, the MATERIAL, or the USER parameter is specified.
The following parameters are optional, mutually exclusive, and used only
if the section is not defined by its general stiffness on the data
lines- COMPOSITE
Include this parameter to indicate that the shell is composed of layers with
different linear elastic material behavior.
- MATERIAL
Set this parameter equal to the name of the single linear elastic material
of which the shell is made.
- USER
This parameter applies only to
Abaqus/Standard
analyses and cannot be used with continuum shell elements. See
Using a general shell section to define the section behavior
for use of this option in linear perturbation analyses.
Include this parameter to indicate that the shell section stiffness is
defined in user subroutine
UGENS.
The following parameters are optional, mutually exclusive, and can be
used only in combination with the MATERIAL, the COMPOSITE, or the USER parameter- NODAL THICKNESS
Include this parameter to indicate that the shell thickness should not be
read from the data lines but should be interpolated from the thickness
specified at the nodes with the
NODAL THICKNESS option. For composite sections the total thickness is
interpolated from the nodes, and the thicknesses of the layers specified on the
data lines are scaled proportionally. This parameter is ignored for continuum
shells.
- SHELL THICKNESS
Set this parameter equal to the name of a distribution (Distribution definition)
to define spatially varying thickness. If this parameter is used for a
non-composite section, the thickness on the data line is ignored. For composite
sections the total thickness is defined by the distribution, and the
thicknesses of the layers specified on the data lines are scaled
proportionally. This parameter is ignored for continuum shells.
The distribution used to define shell thickness must have a default value.
The default thickness is used by any shell element assigned to the shell
section that is not specifically assigned a value in the distribution.
The following optional parameters can be used only in combination with
the USER parameter- I PROPERTIES
Set this parameter equal to the number of integer property values needed as
data in user subroutine
UGENS. The default is I PROPERTIES=0.
- PROPERTIES
Set this parameter equal to the number of real (floating point) property
values needed as data in user subroutine
UGENS. The default is PROPERTIES=0.
- UNSYMM
Include this parameter if the section stiffness matrices are not symmetric.
This parameter will invoke the unsymmetric equation solution capability.
- VARIABLES
Set this parameter equal to the number of solution-dependent variables that
must be stored for the section. The default is VARIABLES=1.
Optional parameter for use when the MATERIAL, the COMPOSITE, and the USER parameters are omitted- DEPENDENCIES
Set this parameter equal to the number of field variable dependencies
included in the definition of the scaling moduli, in addition to temperature.
If this parameter is omitted, it is assumed that the moduli are constant or
depend only on temperature.
Data
line if the MATERIAL parameter is included- First (and only) line
Shell thickness. This value is ignored if the NODAL THICKNESS or SHELL THICKNESS parameter is included.
Data
lines if the COMPOSITE parameter is included- First line
Positive scalar value defining layer thickness or the name of a distribution
(Distribution definition)
that defines spatially varying layer thicknesses. A distribution for composite
layer thickness can be used only for conventional shell elements (not continuum
shell elements). The layer thickness is modified if the NODAL THICKNESS or SHELL THICKNESS parameter is included.
This field is not used (any value given will be ignored). It is included for
compatibility with the
SHELL SECTION option.
Name of the material forming this layer.
Orientation angle, ,
or the name of a distribution (Distribution definition)
that defines spatially varying orientation angles. Orientation angles (in
degrees) are measured positive counterclockwise relative to the orientation
definition given with the ORIENTATION parameter. If the ORIENTATION parameter is not included,
is measured relative to the default shell local directions (see
Conventions).
Name of the ply. Required only for composite layups defined in
Abaqus/CAE.
Repeat this data line as often as necessary to define the
layers of the shell. The order of the laminated shell layers with respect to
the positive direction of the shell normal is defined by the order of the data
lines. If the SYMMETRIC parameter is included, specify only half the layers, from the
bottom layer to the midplane.
Data
lines to define the shell section directly if the MATERIAL, the COMPOSITE, and the USER parameters are omitted- First line
Symmetric half of the
matrix in the order ,
,
,
,
,
,
,...,
,
,...,
,...,
,...,
Repeat this data line three
times. Enter 21 entries total, 8 per line on the first two lines and 5 on the
third line.
- Second line (optional)
vector (,
,
..., ).
- Third line (optional)
Y, scaling modulus for .
The default is 1.0.
,
scaling modulus for .
The default is 0.0.
,
temperature for these values of Y and
.
First field variable.
Second field variable.
Etc., up to five field variables.
- Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)
Sixth field variable.
Etc., up to eight field variables per line.
Repeat this set of data lines
as often as necessary to define Y and
as functions of temperature and other predefined field
variables.
Data
lines to define spatially varying shell section stiffness with a distribution
if the MATERIAL, the COMPOSITE, and the USER parameters are omitted- First line
Distribution name. The data in the distribution define the symmetric half of
the
matrix.
- Second line (optional)
vector (,
,
..., ).
- Third line (optional)
Y, scaling modulus for .
The default is 1.0.
,
scaling modulus for .
The default is 0.0.
,
temperature for these values of Y and
.
First field variable.
Second field variable.
Etc., up to five field variables.
- Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)
Sixth field variable.
Etc., up to eight field variables per line.
Repeat this set of data lines
as often as necessary to define Y and
as functions of temperature and other predefined field
variables.
Data
lines if the USER parameter is included- First line
Shell thickness. This value is ignored if the NODAL THICKNESS or SHELL THICKNESS parameters are included.
- Second line
Enter the data to be used as properties in user subroutine
UGENS. Enter all floating point values first, followed
immediately by the integer values.
Repeat this data line as often as necessary to define the
properties required in
UGENS. Enter eight values per line for both real and integer
values.
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