Workbench, APDL and one Unusual Finite
Element Application
Marcos Giovani Dropa de Bortoli
Júlio César Silva
PRESENTATION TOPICS
• Company Overview
• Problem Description
• Methodology
• Application
• Conclusion
• Abstract
Embraco
• Specialized in cooling solutions, Embraco is the world leader
in the hermetic compressor market for refrigeration.
• Founded in March 1971, it employs, globally, about 12
thousand people. With production capacity of approximately
35 million compressors by year, it sells hundreds of models
tailored to different markets in over 80 countries.
• Embraco is recognized worldwide for the state-of-the-art of
its products and for offering innovative cooling solutions.
Technology is Embraco’s differential to ensure leadership in
its sector.
Embraco – global presence
Introduction
• Usually, the results of a finite element
analysis are:
– displacement
– stress
• For some applications, the results must be
showed in different way (a special post
processing)
• For example, how to evaluate the roundness?
What is roundness?
A component may appear round to the eye
and may even have an apparently constant
diameter, but is it true?
Out-of-roundness is expressed as the
difference between the greatest and least
distance of the profile from a center.
Image from www.taylor-hobson.com
Image from www.taylor-hobson.com
Why is it important to evaluate roundness?
Image from www.taylor-hobson.com
One example: the bearing shown here has
a race that is not truly circular. The
undulations about this bearing race would
cause vibration, and reduce the life of the
bearing.
How to evaluate the roundness?
There are a lot of methods to evaluate the roundness. In this work it will
presented three methods: least squares reference circle, minimum
circumscribed circle and maximum inscribed circle .
Image from www.taylor-hobson.com
Least squares reference circle (LSCI): a
circle is fitted to the data such that the sum
of the squares of the distance between it
and the traced or modified profile of the
workpiece is minimized. Out-of-roundness is
expressed in terms distance between the
highest peek to the lowest valley.
How to evaluate the roundness?
Image from www.taylor-hobson.com
Minimum Circumscribed Circle (MCCI):
defined as the circle of minimum radius
which will enclose the profile data. The out-
of-roundness is then give as the distance
from the lowest valley to the profile from this
circle.
Maximum Inscribed Circle (MICI): defined
as the circle of maximum radius which will
enclose the profile data. The out-of-
roundness is then give as the distance from
the highest peak to the profile from this
circle.
Image from www.taylor-hobson.com
Why is it necessary to evaluate the roundness
numerically?
• Typically, the roundness is a experimentally
process, to evaluate the quality of the components.
• For some components, it is important to calculate
numerically, to analyze the influence of shapes,
material, loads, etc.
• FEM is a efficient tool to help in this subject.
The strategy implementation
• The roundness evaluation is made by a external
program (Fortran language). The input data are the
profile points.
• The FEA is made by Workbench – Import the CAD model
– Create mesh and apply BC
– Solve the problem
– Supply the displacements
• APDL does the connection between Workbench
and the external program (using a macro).
APDL – ANSYS Parametric Design Language
• Language used to communicate with the ANSYS
Mechanical APDL solver
• It can be used to:
– automate common tasks
– build a parametric model
• APDL encompasses a wide range of features:
– if-then-else constructs
– do-loops
– Vector and matrix operations
Macro – input and output
input
output
Macro – the external program
Macro calls
the external
program
Where is the macro?
The example
Typical post processing (displacement)
Improving the post processing
Changing the
coordinate
system
Roundness evaluation
Recommended way!
Not recommended way
Application
position
roundness
experimental
numerical
Conclusion
• APDL is a efficient way to improve the power of
workbench (to do unusual things).
• APDL could be a link between workbench and
external programs.
• It is possible to use the same methodology to
evaluate others geometrical parameters are:
cylindricity, flatness and squareness.
• It is important to guarantee the legacy of the older
works.
• Pay attention about ACT.
Abstract
Normally, the results of a finite element analysis are stress or
displacements. But, for some applications, the results must be
showed in different way, it is necessary a special post processing.
This is the case to evaluate the geometric tolerances, as roundness,
cylindricity, squareness, flatness and parallelism. An alternative to
evaluate these tolerances is creating macros using APDL language,
and with the integration with other languages, as for example,
FORTRAN.
The objective of this paper is to present the importance of the use of
APDL inside of workbench, and the benefits of this junction. To
illustrate the subject, the evaluation of roundness of a compressor
cylinder will be presented, with experimental results to show the
precision of the methodology.
Thank you!
Marcos Giovani Dropa de Bortoli