*SHELL GENERAL SECTION
controls,” Section 21.1.4 of the ABAQUS Analysis User’s Manual) or to be used in a subseq uent
ABAQUS/Explicit import analysis.
OFFSET
Include this parameter to define the distance (as a fraction of theshell thickness) from the shell
midsurface to the reference surface (containingthe 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 cannot be used if the MATERIALand COMPOSITE parameters are omitted.
This parameter is ignored for continuum shells.
ORIENTATION
Set this parameter equal to the name of an orientation definition(see “O rientations,”Section 2.2.5
of the ABAQUS Analysis User’s Manual) to be used with the section forcesand section strains.
POISSON
Include this parameter to define the shell thickness direction behavior.
Set this parameter equal to a nonzerovalue 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.
STACK DIRECTION
This parameter is relevant only for continuum shells.
This parameter defines the continuum shell stack or thickness direc tion. Set this parameter
equal to 1, 2, 3, or ORIENTATION.The default is STACK DIRECTION=3. The ORIENTATION
parameter must also be used if STACKDIRECTION=ORIENTATION.
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 mater ial definition.
ZERO
If the section is defined by its general stiffness, set this parameter equal to , the referen ce
temperature for thermal expansion (for example, ZERO=50 means ).
This parameter is ignored if the COMPOSITE, the MATERIAL,or the USER parameter is
specified.
18.14–2
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