Page 180 - Using ANSYS for Finite Element Analysis Dynamic, Probabilistic, Design and Heat Transfer Analysis

ChaPter 5

Design oPtimization

Optimizing a structure or manufactured product refers to a sequence of
analyses aimed at reducing the weight or cost of the structure or product
while maintaining the functionality of the structure or product, and that
meets all engineering requirements, and that can be manufactured and
assembled. This process may include modifications to the structural or
product topology, component thicknesses, and material properties. The
optimization process is iterative where the specified design variables are
altered, in the course of the optimization process, in a manner that mod-
ifies the objective function (structural or product weight or cost) in an
advantageous manner. “The term optimization, or mathematical program-
ming, refers to the study of problems in which one seeks to minimize or
maximize a real function by systematically choosing the values of real
or integer variables from within an allowed set.” Using the computer to
achieve the most efficient design of a product, finite element analysis
(FEA) and other methods are used. The finite element method (FEM) is
among the most powerful tool for nonlinear simulations.
In the past, design engineers have performed a combination of man-
ual and automated methods to accomplish design optimization. They have
applied FEA to parts of a CAD drawing, determined what components
needed work and then redrew the object manually. Increasingly, software
that is tightly integrated with the CAD program can perform the analysis
and automatically redraw the object.

5.1 oPtimum design

The optimum design is the best design in some predefined sense. Among
many examples, the optimum design for a frame structure may be the
one with minimum weight or maximum frequency; in heat transfer, the
minimum temperature; or in magnetic motor design, the maximum peak