Mechanical APDL Structural Analysis Guide

4.4.3.7. Repeat for Additional Load Steps

Repeat the process for any additional loads and frequency ranges (that is, for additional load steps). If
you plan to do time-history postprocessing (POST26), the frequency ranges should not overlap from
one load step to the next. Another method for multiple load steps, which allows you to store the load
steps on files and then solve them at once using a macro, is described in the Basic Analysis Guide.

4.4.3.8. Leave SOLUTION

Command(s):FINISH
GUI:Close the Solution menu.

4.4.4. Review the Results

The results data for a harmonic analysis are the same as the data for a basic structural analysis with the
following additions: If you defined damping in the structure, the response will be out-of-phase with
the loads. All results are then complex in nature and are stored in terms of real and imaginary parts.
Complex results will also be produced if out-of-phase loads were applied. See Review the Results (p. 19)
in Structural Static Analysis (p. 9).

4.4.4.1. Postprocessors

You can review these results using either POST26 or POST1.The normal procedure is to first use POST26
to identify critical forcing frequencies - frequencies at which the highest displacements (or stresses)
occur at points of interest in the model - and to then use POST1 to postprocess the entire model at
these critical forcing frequencies.

• POST1 is used to review results over the entire model at specific frequencies.


• POST26 allows you to review results at specific points in the model over the entire frequency range.

Some typical postprocessing operations for a harmonic analysis are explained below. For a complete
description of all postprocessing functions, see An Overview of Postprocessing in the Basic Analysis
Guide.

4.4.4.2. Points to Remember

The points to remember for a harmonic analysis are the same as those for most structural analyses. See
Points to Remember (p. 19) in Structural Static Analysis (p. 9).

4.4.4.3. Using POST26.

POST26 works with tables of result item versus frequency, known as variables. Each variable is assigned
a reference number, with variable number 1 reserved for frequency.

1. Define the variables using these options:
   Command(s):NSOL,ESOL,RFORCE

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Harmonic Analysis