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

marcos_g_bortoli@embraco.com.br