Page 193 - Using ANSYS for Finite Element Analysis Dynamic, Probabilistic, Design and Heat Transfer Analysis

180 • using ansys for finite eLement anaLysis
establish the analysis file for your model. Then all operations within the
optimizer can be performed interactively, allowing the freedom to probe
your design space before the actual optimization is done. The insights
you gain from your initial investigations can help to narrow your design
space and achieve greater efficiency during the optimization process.
(The interactive features can also be used to process batch optimization
results.)
The process involved in design optimization consists of the following
general steps. The steps may vary slightly, depending on whether you are
performing optimization interactively (through the GUI), in batch mode,
or across multiple machines.

1. Create an analysis file to be used during looping. This file should
represent a complete analysis sequence and must do the following:
• Build the model parametrically (PREP7).
• Obtain the solution(s) (SOLUTION).
• Retrieve and assign to parameters the response quantities that
will be used as state variables and objective functions (POST1/
POST26).
2. Enter OPT and specify the analysis file (OPT).
3. Declare optimization variables (OPT).
4. Choose optimization tool or method (OPT).
5. Specify optimization looping controls (OPT).
6. Initiate optimization analysis (OPT).
7. Review the resulting design sets data (OPT) and postprocess results
(POST1/POST26).

1. Create the analysis file
The analysis file is a key component and crucial to ANSYS opti-
mization. The program uses the analysis file to form the loop file,
which is used to perform analysis loops. Any type of ANSYS anal-
ysis (structural, thermal, magnetic, etc.; linear or nonlinear) can
be incorporated in the analysis file. In this file, the model must be
defined in terms of parameters (which are usually the DVs), and
results data must be retrieved in terms of parameters (for SVs and
the objective function). Only numerical scalar parameters are used
by the design optimizer. There are two ways to create an analysis
file:
• Input commands line by line with a system editor.
• Create the analysis interactively through ANSYS and use the
ANSYS command log as the basis for the analysis file.