ABAQUS Volume II: I–Z - Manual (Page 422)

*SHELL SECTION
DENSITY
Set this parameter equal to a mass per unit surface area of the shell.
If this parameter is used, the mass of the shell includes a contribution from this parameter in
addition to any contribution from the material definition.
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.
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 or the labels SPOS or SNEG.
Positive values of the offset are in the positive normal direction (see “Shell elements:
overview,” Section 23.6.1 of the ABAQUS Analysis User’s Manual). 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. This parameter is ignored for continuum
shells.
ORIENTATION
Set this parameter equal to the name of an orientation definition (“Orientations,” Section 2.2.5 of
the ABAQUS Analysis User’s Manual) to be used with material calculations in this definition of
shell section behavior. This orientation will be used for material calculations and stress output in
the individual layers, for the section forces output, and for the transverse shear stiffness.
It is possible to use a different orientation definition for material calculations in the individual
layers of a composite shell by referencing an orientation definition or giving an orientation angle
(in degrees, positive counterclockwise relative to the shell local directions) on each layer definition
data line. Any layer definition line that does not have an orientation reference or an angle specified
will use the orientation defined here.
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
elastic part of the material definition.
Set POISSON=MATERIAL in an ABAQUS/Explicit analysis to cause the thickness direction
strain under plane stress conditions to be a function of the membrane strains and the in-plane material
properties.
18.15–2
ABAQUS Version 6.1 Module: ID:
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