Page 196 - Using ANSYS for Finite Element Analysis Dynamic, Probabilistic, Design and Heat Transfer Analysis

Design optimization • 183

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2. Enter OPT and specify the analysis file
The remaining steps are performed within the OPT processor.
When you first enter the optimizer, any parameters that exist in the
ANSYS database are automatically established as design set num-
ber 1. To enter the optimizer, use one of these methods:
Command(s): /OPT
GUI: Main Menu> Design Opt
In interactive mode, you must specify the analysis file name.
To specify the analysis file name, use one of these methods:
Command(s): OPANL
GUI: Main Menu> Design Opt> Analysis File> Assign
3. Declare optimization variables
The next step is to declare optimization variables, that is, specify
which parameters are DVs, which ones are SVs, and which one is
the objective function. As mentioned earlier, up to 60 DVs and up
to 100 SVs are allowed, but only one objective function is allowed.
To declare optimization variables, use one of these methods:
Command(s): OPVAR
GUI:
Main Menu> Design Opt> Design Variables
Main Menu> Design Opt> State Variables
Main Menu> Design Opt> Objective
Minimum and maximum constraints can be specified for SVs
and DVs. Constraints are needed for the objective function. Each
variable has a tolerance value associated with it, which you may
input or let default to a program-calculated value.
4. Choose optimization tool or method
In the ANSYS program, several different optimization tools and
methods are available. Single loop is the default. To specify a tool
or method to be used for subsequent optimization looping, use one
of these methods:
Command(s): OPTYPE
GUI: Main Menu> Design Opt> Method/Tool
5. Specify optimization looping controls
Each method and tool has certain looping controls associated with
it, such as maximum number of iterations, and so on. All of the
commands that you use to set these controls are accessed by the
menu path Main Menu> Design Opt> Method/Tool.
There are also a number of general controls that affect how
data is saved during optimization. They are as follows: