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Technical Overview
62
divided to create new curves. Other operations such as
absolute value, square root, logarithm, exponential,
and maximum and minimum determinations can be
used. Differentiation and integration of the curves may
be done to produce additional curves such as velocity
and acceleration. It can also be used to generate
response spectra (for use in a spectrum analysis) from
time-history results.
TEMP
(1E+3)
1.00
.88
.75
.63
6
.50
25
26
27
7
9
.38
.25
.13
0
–.13
–.25
0
4.0
2.0
8.0
6.0
12.0
10.0
16.0
14.0
20.0
TIME
18.0
Brake Disk Transient
Figure 37
The time-history postprocessor easily produces time-history graphs.
Here, the temperature solution time-history of several nodes on
a thermal model is monitored throughout a transient analysis.
ANSYS Parametric
Language
Design
The normal procedure for performing an analysis using
the finite element method involves defining the model
and its loading, obtaining a solution, and interpreting
the results. If the solution results indicate that a design
change is necessary, the geometry of the model must be
changed and the process repeated. This procedure can
be very costly and time-consuming, especially if the
model is complex or many changes must be made.
ANSYS Parametric Design Language (APDL)
gives the user the ability to automate this cycle by setting
up an “intelligent” analysis; that is, the program input
can be set up to make decisions based on specified
functions, variables, and selected analysis criteria. APDL
allows for sophisticated data input, giving the user control over virtually any design or analysis entity such as
dimensions, materials, loadings, constraint locations,
and mesh refinement. APDL expands ANSYS capabilities beyond the realm of traditional FEA and into more
advanced operations, including sensitivity studies, parametric modeling from parts libraries, innovative design
changes, and design optimization.
The extent to which APDL can be employed to
maximize the program’s efficiency is limited only by
the ingenuity of the user. For example, a company that
manufactures gears may use the ANSYS program to
analyze all of its new designs. The user can develop one
generalized set of ANSYS input commands to describe
the basic definition of a gear, including material properties, geometry, and other design parameters that gears
may have in common. The user can quickly set up and
perform an analysis for virtually any type of gear the
manufacturer designs by changing specific values for
the appropriate entities in this master set of input
commands, and an analysis can be quickly set up.
Even more sophisticated use of APDL features in
this example might be to automate the gear design
process. The generalized ANSYS command file can be
set up to prompt the engineer for detailed gear parameters (such as dimensions, material properties, number
of gear teeth, pitch, loadings, etc.). Based on this data,
the ANSYS program would create the gear model
geometry and loadings, and execute the appropriate
analysis. Furthermore, the program could be directed
to retrieve the analysis results and decide if the gear
design is acceptable based on defined limitations.
APDL consists of the following features, which
can be used together or separately as desired:
• Parameters
• Array Parameters
• Expressions and Functions
• Branching and Looping
• Repeat Functions and Abbreviations
• Macros
• User Routines