Mechanical APDL Basic Analysis Guide

ample, the commands shown below define two element types,BEAM188 and SHELL181, and assign
them type reference numbers 1 and 2 respectively.

ET,1,BEAM188

ET,2,SHELL181

This table of type reference number versus element name is called the element type table. While defining
the actual elements, you point to the appropriate type reference number using the TYPE command
(Main Menu> Preprocessor> Modeling> Create> Elements> Elem Attributes).

Key Options

Many element types have key options, or KEYOPTs, and are referred to as KEYOPT(1), KEYOPT(2), etc.
For example, KEYOPT(3) for BEAM188 allows you to choose the shape function along the length of the
beam, and KEYOPT(8) for SHELL181 allows you to specify how layer data should be stored.

Specify KEYOPTs via the ET command or the KEYOPT command (Main Menu> Preprocessor> Element
Type> Add/Edit/Delete).

1.1.3. Defining Element Real Constants

Element real constants are properties that depend on the element type, such as the cross-sectional
properties of a beam element. Not all element types require real constants, and different elements of
the same type may have different real constant values.

You can specify real constants using the R family of commands (R,RMODIF, etc.) or their equivalent
menu paths; see the Command Reference for further information. As with element types, each set of
real constants has a reference number, and the table of reference number versus real constant set is
called the real constant table. While defining the elements, you point to the appropriate real constant
reference number using the REAL command (Main Menu> Preprocessor> Modeling> Create> Ele-
ments> Elem Attributes).

While defining real constants, keep these rules and guidelines in mind:

• When using one of the R commands, you must enter real constants in the order shown in Table 4.n.1
  for each element type in the Element Reference.


• For models using multiple element types, use a separat e real constant set (that is, a different REAL
  reference number) for each element type. The program issues a warning message if multiple element
  types reference the same real constant set. However, a single element type may reference several
  real constant sets.


• To verify your real constant input, use the RLIST and ELIST commands, with RKEY = 1 (shown below).
  RLIST lists real constant values for all sets. The command ELIST,,,,,1 produces an easier-to-read list
  that shows, for each element, the real constant labels and their values.
  Command(s):ELIST
  GUI: Utility Menu> List> Elements> Attributes + RealConst
  Utility Menu> List> Elements> Attributes Only
  Utility Menu> List> Elements> Nodes + Attributes
  Utility Menu> List> Elements> Nodes + Attr + RealConst
  Command(s):RLIST
  GUI: Utility Menu> List> Properties> All Real Constants
  Utility Menu> List> Properties> Specified Real Const

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