Mechanical APDL Basic Analysis Guide

• For line and area elements that require geometry data (cross-sectional area, thickness, diameter, etc.)
  to be specified as real constants, you can verify the input graphically by using the following commands
  in the order shown:
  Command(s):/ESHAPE and EPLOT
  GUI: Utility Menu> PlotCtrls> Style> Size and Shape
  Utility Menu> Plot> Elements

The program displays the elements as solid elements, using a rectangular cross-section for link and
shell elements and a circular cross-section for pipe elements. The cross-section proportions are determined
from the real constant values.

1.1.3.1. Creating Cross Sections

If you are building a model using BEAM188or BEAM189, you can use the section commands (SECTYPE,
SECDATA, etc.) or their GUI path equivalents to define and use cross sections in your models. See Beam
Analysis and Cross Sections in the Structural Analysis Guide for information on how to use the BeamTool
to create cross sections.

1.1.4. Defining Material Properties

Most element types require material properties. Depending on the application, material properties can
be linear (see Linear Material Properties (p. 4)) or nonlinear (see Nonlinear Material Properties (p. 7)).

As with element types and real constants, each set of material properties has a material reference
number. The table of material reference numbers versus material property sets is called the material
table. Within one analysis, you may have multiple material property sets (to correspond with multiple
materials used in the model). The program identifies each set with a unique reference number.

While defining the elements, you point to the appropriate material reference number using the MAT
command.

1.1.4.1. Linear Material Properties

Linear material properties can be constant or temperature-dependent, and isotropic or orthotropic. To
define constant material properties (either isotropic or orthotropic), use one of the following:
Command(s):MP
GUI: Main Menu> Preprocessor> Material Props> Material Models

(See Material Model Interface (p. 8) for details on the GUI.)

You also must specify the appropriate property label; for example EX, EY, EZ for Young's modulus, KXX,
KYY, KZZ for thermal conductivity, and so forth. For isotropic material you need to define only the X-
direction property; the other directions default to the X-direction value. For example:

MP,EX,1,2E11! Young's modulus for material ref. no. 1 is 2E11

MP,DENS,1,7800! Density for material ref. no. 1 is 7800

MP,KXX,1,43! Thermal conductivity for material ref. no 1 is 43

Besides the defaults for Y- and Z-direction properties (which default to the X-direction properties),
other material property defaults are built in to reduce the amount of input. For example, Poisson's ratio
(NUXY) defaults to 0.3, shear modulus (GXY ) defaults to EX/2(1+NUXY )), and emissivity (EMIS) defaults
to 1.0. See the Element Reference for details.

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