Mechanical APDL Structural Analysis Guide

3. Refine the section mesh. (Main Menu> Preprocessor> Sections> Beam> Custom Sectns> Edit/Built-
   up> Refine Mesh)


4. Modify the cell materials. (Main Menu> Preprocessor> Sections> Beam> Custom Sectns> Edit/Built-
   up> Modify Material) If you want to create a multiple-material section, define the materials. This is ne-
   cessary to calculate the shear correction factors and material-weighted centroids.


5. Save the section to a .SECT file using SECWRITE (Main Menu> Preprocessor> Sections> Beam>
   Custom Sectns> Edit/Built-up> Save).


6. To calculate the section properties and use a custom section in the analysis, read in the user mesh file
   (Main Menu> Preprocessor> Sections> Beam> Custom Sectns> Read Sect Mesh).

Note

If you redefine a material after creating the section, you must reissue the SECTYPE and

SECREAD commands to recalculate the cross section.

When a cross section has multiple materials, and /ESHAPE is used to produce contour plots

of stresses (and other quantities), the element averages the stresses across material bound-

aries. To limit this behavior, use small cross section cells around the material boundaries.

When using the SECWRITE command explicitly, a section with multiple materials can be

created by assigning material attributes to the areas. During meshing, the elements inherit

the material attribute from the area and this attribute is written to the .SECT file.

A material number (MAT) specified for a custom section overrides any existing material setting.

15.3.4. Defining Composite Cross Sections

A composite cross section is a cross section consisting of at least two materials and meshed with a user-
defined mesh.When creating a composite section, define the materials before running the SECREAD
command. This is necessary to calculate the shear correction factors, material-weighted centroids and
the shear centers.

Note

If you redefine a material after creating the section, you must reissue the SECREAD command

to recalculate the cross section.

You can save composite cross sections as custom cross sections. For information on custom cross sections,
see Using the Beam Tool to Create Common Cross Sections (p. 439)

15.3.5. Defining a Tapered Beam

For BEAM188 and BEAM189, you can define tapered beams using the TAPER option on the SECTYPE
command (Main Menu> Preprocessor> Sections> Beam> Taper Sections). The tapered section varies
linearly between two specified locations, (x1, y1, z1) and (x2, y2, z2).Thus, two SECDATA commands
are required to define the taper as shown below. At each of these end points, a valid beam section ID
must be input (station-1 and station-2 in the example below).

SECTYPE,SECID,TAPER

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

Creating Cross Sections