*
SHELL SECTION
DENSITY
Set this parameter equal to a m ass per unit surface area of the shell.
If this parameter is used, the mass of t he shell includes a contribution from this parameter in
addition to a ny contribution from the material definition.
NODAL THICKNESS
Include this p arameter to indica te that the shell thickness should not be read from the data lines but
should be interpola ted from the thickness specified at the nodes with the
*
NODAL THICKN ESS
option. For composite secti ons the total thickness is interpolated from the nodes and the thicknesses
of the layers specified on the data lines are scaled propor tionally. 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 ele ments:
overview,” Section 23.6.1 of the ABAQUS A nalysis User’s Manual). When O FFSET=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 param eter 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 orie ntation will be used for material calculat ions and stress output in
the individual layers, for the section forces output, and for the transverse shear stiffness.
It is possible to us e a different orientation d efinition for material calculations in the individual
layers of a com posite 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 thick ness direction behav ior.
Set this parameter equal to a nonzero value to cause the thickness direction strain under plane
stress condition s to be a linear function of the membrane strains. The value of the POISSO N
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 afunctionof the membrane strains and the in-plane material
properties.
18.15–2
ABAQUS Version 6.1 Module:
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