Page 192 - Using ANSYS for Finite Element Analysis Dynamic, Probabilistic, Design and Heat Transfer Analysis

Design optimization • 179
the direction of each design variable while holding all other design vari-
ables fixed at their reference values. The state variables and the objective
function are computed and stored for subsequent display at each sweep
evaluation point.
A sweep execution will produce n design sets calculated from:
s
n�� = nN s
s
Where:
n = number of design variables
N = number of evaluations to be made in the direction of each design
s
variable.

5.2.3.4 Factorial Tool

This is a statistical tool that is used to generate design sets at all
extreme combinations of design variable values. This technique is
related to the technology known as design of experiment that uses a
two-level, full and fractional factorial analysis. The primary aim is to
compute main and interaction effects for the objective function and the
state variables.

5.2.3.5 gradient Tool

The gradient tool computes the gradient of the state variables and the
objective function with respect to the design variables. A reference design
set is defined as the point of evaluation for the gradient. Using this tool,
you can investigate local design sensitivities.

5.2.4 geneRAL PRoCeSS FoR DeSign oPTiMizATion

One can approach an ANSYS optimization in two ways: as a batch run or
interactively via the graphical user interface (GUI). If you are familiar with
ANSYS commands, you can perform the entire optimization by creating an
ANSYS command input file and submitting it as a batch job. This may be
a more efficient method for complex analyses (e.g., nonlinear) that require
extensive run time. Alternatively, the interactive features of optimization
offer greater flexibility and immediate feedback for review of loop results.
When performing optimization through the GUI, it is important to first