Mechanical APDL Structural Analysis Guide

Command Quantity Defined and Data Specified

Transverse shear stiffness -- Symmetric part of

submatrix [E]

SSPE [ 1 ]

E 11 ,E 21 ,E 22 ,T

SSMT Membrane thermal effects -- {MT}

MT 11 ,MT 22 ,MT 12 ,T

SSBT [ 1 ] Bending thermal effects -- {BT}

BT 11 ,BT 22 ,BT 12 ,T

Mass density of the shell section (assuming a

unit thickness)

SSPM

DENS,T

1. If you are using the SHELL181 or SHELL281 element's Membrane option (KEYOPT(1) = 1), it is not necessary
   to issue the SSPB,SSPD,SSPE, and SSBT commands. In this case, the only relevant quantities are
   membrane stiffness (SSPA), membrane thermal effects (SSMT), and density (SSPM).

Temperature dependencies (T) You can define each of the preintegrated shell section data as
temperature-dependent. It is possible to specify up to six temperatures (T) by reissuing any command
as necessary. If you issue a command for a temperature specified earlier, the most recent data supersedes
the previous value.

16.3.2. Considerations for Using Preintegrated Shell Sections

You can define preintegrated shell sections only when using the SHELL181 or SHELL281 element. When
using preintegrated shell section data, the following conditions apply:

• The section data defined by each command listed in Table 16.2: Commands for Specifying Preintegrated
  Shell Section Data (p. 466) is associated with the section most recently defined via the SECTYPE command.


• You cannot use the shell element with heat-transfer shells.


• Shell stresses are not available for output; however, the stress resultants are available as ETABLE quantities.


• The thickness of the shell is assumed to remain constant even in a large-strain analysis.


• Section offsetting (SECOFFSET) is not available.


• The preintegrated stiffness components must yield a positive definite section stiffness at analysis time.

If using preintegrated shell sections in a contact analysis, ANSYS, Inc. recommends the pure Lagrange
multiplier method.

For standard layered-shell sections, you can obtain submatrices [A], [B], [D], and [E] via the SLIST com-
mand's FULL option.

Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information

Using Preintegrated General Shell Sections