Mechanical APDL Basic Analysis Guide

7.2.5. Mapping Results onto a Path

One of the most powerful and useful features of POST1 is its ability to map virtually any results data
onto an arbitrary path through your model. This enables you to perform many arithmetic and calculus
operations along this path to calculate meaningful results: stress intensity factors and J-integrals around
a crack tip, the amount of heat crossing the path, magnetic forces on an object, and so on. A useful
side benefit is that you can see, in the form of a graph or a tabular listing, how a result item varies
along the path.

Note

You can define paths only in models containing solid elements (2-D or 3-D) or shell elements.

They are not available for line elements.

Three steps are involved in reviewing results along a path:

1. Define the path attributes (PATH command).


2. Define the path points (PPATH command).


3. Interpolate (map) results data along the path (PDEF command).

Once the data are interpolated, you can review them using graphics displays (PLPATH or PLPAGM
commands) and tabular listings or perform mathematical operations such as addition, multiplication,
integration, etc. Advanced mapping techniques to handle material discontinuities and accurat e compu-
tations are offered in the PMAP command (issue this command prior to PDEF).

Other path operations you can perform include archiving paths or path data to a file or an arra y para-
meter and recalling an existing path with its data. The next few topics discuss path definition and usage.

7.2.5.1. Defining the Path

To define a path, you first define the path environment and then the individual path points. Decide
whether you want to define the path by picking nodes, by picking locations on the working plane, or
by filling out a table of specific coordinate locations. Then create the path by picking or by using both
of the commands shown below or one of the following menu paths:
Command(s):PATH,PPATH
GUI: Main Menu> General Postproc> Path Operations> Define Path> By Nodes
Main Menu> General Postproc> Path Operations> Define Path> On Working Plane
Main Menu> General Postproc> Path Operations> Define Path> By Location

Supply the following information for the PATH command:

• A path name (containing no more than eight characters).


• The number of path points (between 2 and 1000). Required only in batch mode, or when defining
  path points using the "By Location" option.When picking is used, the number of path points equals
  the number of picked points.


• The number of sets of data which may be mapped to this path. (Four is the minimum; default is 30.
  There is no maximum.)


• The number of divisions between adjacent points. (Default is 20; there is no maximum.)

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