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Students' QuickField (TM)
Finite Element Analysis System
Version 3.4
User's Guide
Copyright (C) Tera Analysis Company, 1995.
All Rights Reserved.
The information contained in this document is subject to change without
notice.
Tera Analysis Co.
P.O. Box 571086,
Tarzana, CA 91357
E-mail: terainfo@tera-analysis.com
URL: http://www.tera-analysis.com
Tel: 818 831 9662
Fax: 805 493 2172
QuickField is a trademark of Tera Analysis Company.
DXF is a trademark of Autodesk, Inc.
IBM PC/AT and PC-DOS are trademarks of International Business Machines
Corporation.
Microsoft and MS-DOS are registered trademarks, and Windows and Microsoft
Word are trademarks, of Microsoft Corporation.
Adobe, Adobe Illustrator, and PostScript are registered trademarks of Adobe
Systems, Inc.
All other brand and product names are trademarks or registered trademarks
of their respective owners.
Table Of Contents
1. Getting Started
2. Required Hardware Configuration
2.1 QuickField Installation
2.2 Starting QuickField
2.3 Quitting QuickField
3. Introductory Guide
3.1 Basic Organization of QuickField
3.2 Overview of Analysis Capabilities
3.2.1 Magnetostatic Analysis
3.2.2 Harmonic Magnetic Field
3.2.3 Electrostatic Analysis
3.2.4 Current Flow Analysis
3.2.5 Thermal Analysis
3.2.6 Stress Analysis
4. Basic Skills
4.1 Terminology
4.2 Working with Menus
4.3 Working with Dialog Boxes
4.3.1 Command Buttons
4.3.2 Text Boxes
4.3.3 List Boxes
4.3.4 Drop-Down List Boxes
4.3.5 Option Buttons
4.3.6 Check Boxes
4.4 Selecting Geometric Objects
4.5 Using Rubber Band Rectangle
5. Problem Description
5.1 Structure of Problem Database
5.2 Creating a New Problem
5.3 Establishing Coupling Links
5.4 Choosing Length Units
5.5 Cartesian vs. Polar Coordinates
6. Model Geometry Definition
6.1 Terminology
6.2 How to Create a Model
6.2.1 Starting and Quitting the Model Editor
6.2.2 Objects Selection
6.2.3 Geometry Description
6.2.4 Copying and Moving Geometric Objects
6.2.5 Labeling Vertices, Edges and Blocks
6.2.6 Building the Mesh
6.2.7 Zooming
6.2.8 Obtaining Model Information
6.3 Additional Options
6.3.1 Saving Model
6.3.2 Opening Model File
6.3.3 DXF File Import
6.3.4 Discretization Visibility Options
6.3.5 Attraction Distance Parameter
7. Problem Parameters Description
7.1 Creating a New Label
7.2 Editing Label Data
7.2.1 Editing Data in Magnetostatics
7.2.2 Editing Data in Harmonic Magnetics
7.2.3 Editing Data in Electrostatics
7.2.4 Editing Data with Current Flow Problems
7.2.5 Editing Data with Heat Transfer Problems
7.2.6 Editing Data with Stress Analysis Problems
7.2.7 Editing the Curves
7.3 Copying, Renaming and Deleting Labels
7.4 Merging and Copying Data Files
8. Solving the Problem
9. Analyzing Solution
9.1 Starting and Quitting the Postprocessor
9.2 Building the Field Picture on the Screen
9.2.1 Interpreted Quantities
9.2.2 Field Presentation Methods
9.2.3 Field Picture Constructing
9.2.4 Zooming
9.3 Access to Local Field Data
9.4 X-Y Plots
9.4.1 Editing Contours
9.4.2 X-Y Plot Control
9.4.3 Zooming the X-Y Plot
9.5 Calculating Integrals
9.6 Saving Prepared Results to Files
9.6.1 Saving the Screen Picture
9.6.2 Exporting Local Values to the Table File
9.6.3 Exporting Field Values along the Contour to the Table File
9.6.4 Fast Printing the Results
9.7 Additional Options
9.7.1 Saving the Postprocessor State
9.7.2 Controlling Legend Display
9.7.3 Changing Color Scheme
10. Examples
10.1 Magnetic Problems
10.1.1 MAGN1: Nonlinear Permanent Magnet
10.1.2 MAGN2: Solenoid Actuator
10.1.3 MAGN3: Ferromagnetic C-Magnet
10.2 Time-Harmonic Magnetics Problem
10.2.1 HMAGN1: Slot Embedded Conductor
10.2.2 HMAGN2: Symmetric Double Line of Conductors
10.3 Electrostatic Problems
10.3.1 ELEC1: Microstrip Transmission Line
10.3.2 ELEC2: Two Conductor Transmission Line
10.4 Heat Transfer Problems
10.4.1 HEAT1: Slot of an Electric Machine
10.4.2 HEAT2: Cylinder with Temperature Dependent Conductivity
10.5 Stress Analysis Problems
10.5.1 STRES1: Perforated Plate
10.6 Coupled Problems
10.6.1 COUPL1: Stress Distribution in a Long Solenoid
10.6.2 COUPL2: Cylinder Subject to Temperature and Pressure
10.6.3 COUPL3: Temperature Distribution in an Electric Wire
About This Manual
What Is QuickField?
Welcome to QuickField Finite Elements Analysis System. QuickField is a
PC-oriented interactive environment for electromagnetic, thermal and stress
analysis. Standard analysis types include:
* Electrostatics.
* Linear and nonlinear magnetostatics.
* Harmonic magnetics (involving eddy current analysis).
* Linear and nonlinear heat transfer and diffusion.
* Linear stress analysis.
* Coupled problems.
During a 15-minute session, you can describe the problem (geometry,
material properties, sources and other conditions), obtain solution with
high accuracy and analyze field details looking through full color picture.
With QuickField, complicated field problems can be solved on your PC
instead of large mainframes or workstations.
How to Use this Manual
This manual has nine chapters:
Chapter 1, "Getting Started", describes first steps of using QuickField. In
this chapter, you will learn how to install and start the package.
Chapter 2, "Introductory Guide", briefly describes the organization of
QuickField and gives an overview of analysis capabilities.
Chapter 3, "Basic Skills", tells you about working patterns with
QuickField.
Chapter 4, "Problem Description", explains how to specify the analysis type
and general problem features.
Chapter 5, "Model Geometry Definition", explains how to describe geometry
of the model, build the mesh, and define material properties and boundary
conditions.
Chapter 6, "Problem Parameters Description", introduces non-geometric data
file organization, and the way to attach this file to the model.
Chapter 7, "Solving the Problem", tells you how to start the solver to
obtain analysis results.
Chapter 8, "Analyzing Solution", introduces QuickField Postprocessor, its
features and capabilities.
Chapter 9, "Examples", contains description of some example problems, which
can be analyzed using QuickField.
Conventions
In this manual we use CAPITAL LETTERS to specify the names of keys on your
keyboard. For example, ENTER, ESC, or ALT. Four arrows on the keyboard,
collectively named the DIRECTION keys, are named for the direction the key
points: UP ARROW, DOWN ARROW, RIGHT ARROW, and LEFT ARROW.
A plus sign (+) between key names means to hold down the first key while
you press the second key. A comma (,) between key names means to press the
keys one after the other.
"Text in quotation marks" is used for QuickField menu and dialog options.
1. Getting Started
2. Required Hardware Configuration
Computer: A 286 or higher Intel processor based
IBM PC compatible.
Coprocessor: Intel 287 or higher math coprocessor.
Memory: 640K.
Display: EGA, VGA color or LCD monochrome.
Mouse: Microsoft mouse or 100% compatible with
Microsoft mouse driver, version 8.00 or
above.
Operating System: MS-DOS, or PC-DOS (Rev. 3.3 or above).
2.1 QuickField Installation
Distribtuion kit of QuickField 3.4 (Students' QuickField) consist of four
archive files:QFLD34-1.ZIP, QFLD34-2.ZIP, QFLD34-3.ZIP, QFLD34-4.ZIP
After unzipping (don't forget -d switch to restore directory structure)
QuickField directory should contain:
six ASCII files:
* FILE_ID.DIZ - descriptor;
* README.TXT - primary information;
* MANUAL.TXT - system documentation;
* REG_FORM.TXT - registration form;
* VENDOR.TXT - information for shareware distributors;
* FAQ.TXT - frequently asked questions about QuickField.
and two subdirectories:
* BIN - contains all the files needed to run QuickField;
* EXAMPLES - contains example problems.
The BIN directory contains all the necessary to run the package. These
files are to be copied to the special directory on the hard disk, for
example, C:\QF\BIN. For your convenience, we recommend to include the name
of this directory to DOS PATH environment variable.
The EXAMPLES directory contains a number of problems solved with
QuickField. We suggest you to look through the examples in the area of your
interest, before you start with your own problems.
To operate with large amount of data, QuickField creates temporary file in
the current working directory. You can specify alternate place for this
file by assigning path of the preferred directory to QFTEMP environment
variable, e.g., to store temporary files in the C:\TEMP directory, you
could include SET QFTEMP=C:\TEMP line in your AUTOEXEC.BAT.
QuickField can use the extended memory of PC. This feature is available
through the XMS driver, e.g., HIMEM.SYS distributed with MS-DOS 5.0 and 6.x
and Microsoft Windows 3.x.
Note. QuickField uses part of the extended memory that is not
occupied by RAM disks, disk caching systems or other resident
programs.
The BIN directory of QuickField distribution kit contains four files with
.CFG extension. These files contain optional color tables:
SCREENC.CFG color table for VGA and EGA color monitors;
SCREENL.CFG color table for LCD monitor of Laptop;
SCREENG.CFG gray scale color table, can be used when obtaining screen
hard copy on a monochrome printer;
SCREEN.CFG default color table, the same as SCREENC.CFG.
You can change the default by replacing SCREEN.CFG on your hard disk with a
copy of the color table you prefer.
Installation under Windows
If you are not planning to run QuickField under Windows, you can skip the
rest of this section.
The installation under Windows 3.x is done after completion the normal
installation procedure. While in Program Manager, select the program group
you want to add QuickField to, or create a new program group called
QuickField. From the File menu of Program Manager, choose New. In the New
Program Item dialog box, select the Program Item option, and then choose
the OK button.. In Program Item Properties dialog box., type "QuickField
3.4" in Description line. Choose the Browse button, and in Browse dialog
box, select the QFIELD.PIF file from the QuickField BIN directory. Choose
the OK button to return to Program Item Properties dialog box. Choose the
Change Icon button. Choose OK button to get to Change Icon dialog box.
Choose the Browse button and select the QFIELD.ICO file from the BIN
directory. Choose the OK button three times to complete the installation
process.
Now you can start QuickField under Windows by double clicking its icon.
Additional Configuration Options
QuickField can use the extended memory of PC. This feature is available
through the XMS driver, e.g., HIMEM.SYS included in MS-DOS 5.0 and 6.x and
in Microsoft Windows 3.x. See Chapter -2 for details how additional memory
can improve performance.
Note. QuickField uses part of the extended memory that is not
occupied by RAM disks, disk caching systems or other resident
programs.
If you do not have extended memory QuickField creates temporary file in the
current working directory.You can specify alternate place for this file by
assigning path of the preferred directory to QFTEMP environment variable,
e.g., to store temporary files in the C:\TEMP directory, you could include
SET QFTEMP=C:\TEMP line in your AUTOEXEC.BAT.
The BIN directory of QuickField contains four files with .CFG extension.
These files represent optional color schemes:
SCREENC.CFG color scheme for VGA and EGA color monitors;
SCREENL.CFG color scheme for a monochrome LCD monitor of Laptop;
SCREENG.CFG gray scale color scheme, can be used when obtaining screen
hard copy on a monochrome printer;
SCREEN.CFG default color scheme, the same as SCREENC.CFG.
You can change the default by replacing SCREEN.CFG on your hard disk with a
copy of the color scheme you prefer.
2.2 Starting QuickField
To start QuickField, go to the directory you devoted for this work and
enter QFIELD at your system prompt. The command line may include the
problem file name. If it does not, the name is taken from QFIELD.INI file
of the previous session. If QFIELD.INI is absent in the current directory,
or does not contain the problem file name, QuickField will ask you for the
name of the problem to work with.
2.3 Quitting QuickField
To exit from QuickField to operating system environment, choose "Exit" from
the "File" menu (ALT+F, X), or press ALT+F4.
3. Introductory Guide
This chapter briefly describes the basic organization of the QuickField
program. It presents an overview of the available capabilities.
The aim of this chapter is to get you started with modeling in QuickField.
If you are new to the QuickField, we strongly recommend you to study this
chapter. If you haven't yet installed QuickField, please do so. For
information on installing QuickField see Getting Started
3.1 Basic Organization of QuickField
QuickField is a menu driven system, when you just get into QuickField you
see the main menus which are located in a horizontal bar on top of the
screen. The four main menus are "File", "Edit", "Results", and "Options".
Here, we briefly describe the functions of these menus and some of their
corresponding submenus.
"File" menu contains all the tools for choosing and manipulating the
database files. For example, you can choose a new problem name or select an
old problem in any existing directory. The detailed description of
operations on problem files is given in Problem Description.
Edit menu contains all the submenus and tools for creating the problem
model and defining all the necessary parameters. It consists of four parts,
"Problem", "Geometry", "Data", and "Library Data".
"Problem" provides you with a dialog box to describe the general problem
parameters, such as the type of analysis ("Electrostatics",
"Magnetostatics", "Heat transfer" and etc.) or the model type (planar or
axisymmetric). The detailed description of how to do this is given in
Problem Description.
"Geometry", takes you to another graphic interface to define the geometry,
the part labels and the mesh for your model. The detailed description of
the geometric modeler is given in Model Geometry Definition.
"Data" provides you with dialog boxes to assign the values of material
properties, loadings and boundary conditions for different part labels, and
"Library Data" allows you to edit the existing data library. The detailed
description of how to specify properties and boundary conditions is given
in Chapter 6.
The "Results" menu contains all the tools for solving your problem and
analyzing the results. It consists of two parts, "Solve Problem" and
"Analyze". After completing the model and assigning all the necessary
parameters, you can choose "Solve Problem" to obtain the solution for your
problem. "Analyze" takes you to a special graphic interface for graphic
display of the results and other postprocessing functions. The detailed
description of how to get and explore the results of the analysis is given
in Chapter 7 and Chapter 8.
Using the above features, QuickField helps you build and analyze your
design problems very quickly. In analyzing a problem, the typical sequence
of phases that you go through with QuickField is depicted in the flowchart
below:
+--------------------------+
! Choose a problem name !
! !
! File: New !
+--------------------------+
!
!
+--------------------------+
! Specify the problem type !
! !
! Edit: Problem !
+--------------------------+
!
!
+--------------------------+
! Define the geometry, !
! part labels and !
! mesh for your model !
! !
! Edit: Geometry !
+--------------------------+
!
!
+--------------------------+
! Provide the data for the !
! materials, loads, !
! boundary conditions !
! !
! File: New !
+--------------------------+
!
!
+--------------------------+
! Obtain the solution !
! !
! Results: Solve Problem !
+--------------------------+
!
!
+--------------------------+
! Review the results and !
! obtain the postprocessing!
! parameters !
! !
! Results: Analyze !
+--------------------------+
3.2 Overview of Analysis Capabilities
This section provides you with the basic information on different analysis
capabilities.
3.2.1 Magnetostatic Analysis
Magnetic analysis is used to design or analyze variety of devices such as
solenoids, electric motors, magnetic shields, permanent magnets, magnetic
disk drives, and so forth. Generally the quantities of interest in
magnetostatic analysis are magnetic flux density, field intensity, forces,
torques, inductance, and flux linkage.
QuickField can perform linear and nonlinear magnetostatic analysis for 2-D
and axisymmetric models. The program is based on a vector potential
formulation. Following options are available for magnetic analysis:
MATERIAL PROPERTIES: air, orthotropic materials with constant permeability,
ferromagnets, current carrying conductors, and permanent magnets. B-H
curves for ferromagnets can easily be defined through an interactive curve
editor, see the "Editing the Curves" section in Chapter 6.
LOADING SOURCES: current density, uniform external field and permanent
magnets.
BOUNDARY CONDITIONS: Prescribed potential values (Dirichlet condition),
prescribed values for tangential flux density (Neumann condition), constant
potential constraint for zero normal flux conditions on the surface of
superconductor.
POSTPROCESSING RESULTS: magnetic potential, flux density, field intensity,
forces, torques, magnetic energy, flux linkage, self and mutual
inductances.
SPECIAL FEATURES: A postprocessing calculator is available for evaluating
user defined integrals on given curves and surfaces. The magnetic forces
can be used for stress analysis on any existing part (magneto-structural
coupling).
3.2.2 Harmonic Magnetic Field
Harmonic magnetic analysis is used to analyze magnetic field caused by
alternating currents and, vise versa, electric currents induced by
alternating magnetic field (eddy currents). This kind of analysis is useful
with different inductor devices, solenoids, electric motors, and so forth.
Generally the quantities of interest in harmonic magnetic analysis are
electric current (and its source and induced component), voltage, generated
Joule heat, magnetic flux density, field intensity, forces, torques,
impedance and inductance.
Following options are available for harmonic magnetic analysis:
MATERIAL PROPERTIES: air, orthotropic materials with constant permeability,
current carrying conductors with known current or voltage.
LOADING SOURCES: voltage, total current, current density, uniform external
field.
BOUNDARY CONDITIONS: Prescribed potential values (Dirichlet condition),
prescribed values for tangential flux density (Neumann condition), constant
potential constraint for zero normal flux conditions on the surface of
superconductor.
POSTPROCESSING RESULTS: magnetic potential, current density, voltage, flux
density, field intensity, forces, torques, Joule heat, magnetic energy,
impedances, self and mutual inductances.
SPECIAL FEATURES: A postprocessing calculator is available for evaluating
user defined integrals on given curves and surfaces. The magnetic forces
can be used for stress analysis on any existing part (magneto-structural
coupling); and power losses can be used as heat sources for thermal
analysis (electro-thermal coupling).
3.2.3 Electrostatic Analysis
Electrostatic analysis is used to design or analyze variety of capacitive
systems such as fuses, transmission lines and so forth. Generally the
quantities of interest in electrostatic analysis are voltages, electric
fields, capacitances, and electric forces.
QuickField can perform linear electrostatic analysis for 2-D and
axisymmetric models. The program is based on Poisson's equation. Following
options are available for electrostatic analysis:
MATERIAL PROPERTIES: air, orthotropic materials with constant permittivity.
LOADING SOURCES: Voltages, and electric charge density.
BOUNDARY CONDITIONS: Prescribed potential values (Voltages), prescribed
values for normal derivatives (surface charges), and prescribed constraints
for constant potential boundaries with given total charges.
POSTPROCESSING RESULTS: voltages, electric fields, gradients of electric
field, flux densities (electric displacements), surface charges, self and
mutual capacitances, forces, torques, and electric energy.
SPECIAL FEATURES: A postprocessing calculator is available for evaluating
user defined integrals on given curves and surfaces. Floating conductors
with unknown voltages and given charges can be modeled. The electrostatic
forces can be used for stresses on any existing part (electro-structural
coupling).
3.2.4 Current Flow Analysis
Current flow analysis is used to analyze variety of conductive systems.
Generally the quantities of interest in current flow analysis are voltages,
current densities, electric power losses (Joule heat).
QuickField can perform linear current flow analysis for 2-D and
axisymmetric models. The program is based on Poisson's equation. Following
options are available for current flow analysis:
MATERIAL PROPERTIES: orthotropic materials with constant resistivity.
LOADING SOURCES: Voltages, electric current density.
BOUNDARY CONDITIONS: Prescribed potential values (Voltages), prescribed
values for normal derivatives (surface current densities), and prescribed
constraints for constant potential boundaries.
POSTPROCESSING RESULTS: voltages, current densities, electric fields,
electric current through a surface, and power losses.
SPECIAL FEATURES: A postprocessing calculator is available for evaluating
user defined integrals on given curves and surfaces. The electric power
losses can be used as heat sources for thermal analysis (electro-thermal
coupling).
3.2.5 Thermal Analysis
Thermal analysis plays an important role in design of many different
mechanical and electrical systems. Generally the quantities of interest in
thermal analysis are temperature distribution, thermal gradients, and heat
losses.
QuickField can perform linear and nonlinear thermal analysis for 2-D and
axisymmetric models. The program is based on heat conduction equation with
convection and radiation boundary conditions. Following options are
available for thermal analysis:
MATERIAL PROPERTIES: orthotropic materials with constant thermal
conductivity, isotropic temperature dependent conductivities.
LOADING SOURCES: constant and temperature dependent volume heat densities,
convective and radiative sources, Joule heat sources imported from current
flow analysis.
BOUNDARY CONDITIONS: Prescribed temperatures, boundary heat flows,
convection, radiation, and prescribed constraints for constant temperature
boundaries.
POSTPROCESSING RESULTS: temperatures, thermal gradients, heat flux
densities, and total heat losses or gains on a given part.
SPECIAL FEATURES: A postprocessing calculator is available for evaluating
user defined integrals on given curves and surfaces. Plate models with
varying thicknesses can be used for thermal analysis. The temperatures can
be used for thermal stress analysis (thermo-structural coupling).
3.2.6 Stress Analysis
Stress analysis plays an important role in design of many different
mechanical and electrical components. Generally the quantities of interest
in stress analysis are displacements, strains and different components of
stresses.
QuickField can perform linear stress analysis for 2-D plane stress, plane
strain, and axisymmetric models. The program is based on Navier equations
of elasticity. Following options are available for stress analysis:
MATERIAL PROPERTIES: isotropic and orthotropic materials.
LOADING SOURCES: concentrated loads, body forces, pressure, thermal
strains, and imported electric or magnetic forces from electrostatic or
magnetostatic analysis.
BOUNDARY CONDITIONS: prescribed displacements, elastic spring supports.
POSTPROCESSING RESULTS: displacements, stress components, principal
stresses, von Mises stress, Tresca, Mohr-Coulomb, Drucker-Prager, and Hill
criteria.
4. Basic Skills
This chapter describes the working environment that you will use with
QuickField.
QuickField is a menu driven system. The meaning of the selected menu item
is explained by the prompt message occupying the bottom line of the screen.
The same line is used for other messages.
In most context the ESC key may be used to cancel or to interrupt the
current action. The right mouse button is completely equivalent to the ESC
key. The left mouse button is used to click objects.
4.1 Terminology
The following terms are used to describe your actions when working with
QuickField.
Choose - To use a mouse or key combination to pick an item that begins an
action. For example, choosing a menu item usually causes the
execution of QuickField command.
Click - To press the mouse button while the tip of the mouse pointer
rests on the item of choice.
Double-click - To click the mouse button twice in rapid succession.
Select - To mark an item by highlighting it with key combinations or by
clicking it with a mouse. Selecting does not initiate an action.
4.2 Working with Menus
To choose a menu item click it with a mouse. You can also use the UP and
DOWN ARROW keys to select the item you want; then press ENTER. If the item
name has an underlined letter, you can type it to choose the menu item with
one step. To select an item on the horizontal menu bar press its underlined
letter while holding down the ALT key.
Pressing the ESC key or clicking the right mouse button returns to the
previous menu level. If you press ESC while in main menu, you will be asked
about exiting to DOS.
4.3 Working with Dialog Boxes
QuickField uses dialog boxes to get information from you and provide
information to you. For example, when QuickField needs additional
information to carry out a command you have chosen, a dialog box requests
the information. You complete the dialog box by providing the missing
information. Whenever you see an ellipsis (...) after a menu command,
another menu or a dialog box follows.
For example, when you choose "Open" from the "File" menu, QuickField
displays a dialog box asking for the name of the file you want to open.
Most dialog boxes contain options, each asking for a different kind of
information. After you supply all the requested information, you choose a
command button to carry out the command.
Often you need to move around within a dialog box to make several
selections. The current option is marked by a highlight or dotted rectangle
(or both) around the name of the option or button. To move within a dialog
box:
* Click the option you want to move to.
* Press TAB to move forward (generally from left to right and top to
bottom) or SHIFT+TAB to move in opposite direction.
* Use the DIRECTION keys to move in desired direction.
* Or, while you hold ALT, you can type the underlined letter in the option
name or group name.
The options that are unavailable for some reason are dimmed.
The next few sections describe different dialog boxes and the procedures
for selecting options.
4.3.1 Command Buttons
Command buttons initiate an immediate action. One command button in each
dialog box carries out the command you choose, using the information
supplied in the dialog box. This button is usually named "OK". Other
command buttons let you cancel the command or choose from additional
options.
Command buttons marked with an ellipsis (...) open another dialog box so
you can provide more information. The currently selected, or default,
button has a highlighted green name or, in a monochrome mode, a darker
border than the other buttons. You can choose the selected button by
pressing ENTER.
You can close the dialog box without completing a command by choosing
"Cancel" button.
To choose a command button:
* Click it.
* Move to the command button you want. A dotted rectangle around the button
text marks the selected button. Press the SPACEBAR (or ENTER) to choose
the button.
* Or, while you hold ALT, you can type the underlined letter in the button
name.
Some dialog boxes are so small that do not contain any command button. Such
dialog boxes are usually located at the right-hand side of the screen and
have gray background. In spite of missing the "OK" command button, it is
still possible to use a mouse to carry out the command you choose. Click
the dialog box background anywhere outside options. The effect will be the
same as if using the "OK" command button.
4.3.2 Text Boxes
A text box is a rectangle into which you type information.
When you move to an empty text box, a text cursor appears at the left side
of the box. The text you type starts at the cursor position.
If the box already contains text when you move to it, all the text in the
box is automatically selected and any text you type replaces it. Or, you
can erase the existing text by pressing DEL. To discard the selection
simply move the cursor to the point where you want to enter or erase text.
Use LEFT and RIGHT ARROW, HOME or END keys to move the cursor.
The text exceeding the length of the text box is scrolled automatically.
4.3.3 List Boxes
The list box shows a column of available choices. If there are more choices
than can fit in the list box, a scroll bar is provided so that you can use
your mouse to move up and down quickly through the list.
To scroll one line click one of the scroll arrows. To scroll one window up
or down click the gray background of the scroll bar above or below the
white rectangle.
When the required item is already visible in the list box, you can select
it by clicking it with a mouse. You also can double-click the item to
choose it and complete the command at once.
To select an item using a keyboard press UP or DOWN ARROW key until you
reach your choice. You also can use PAGE UP and PAGE DOWN to move one
window a time, and HOME or END to move to the first or to the last item of
the list. Or, type the first letter of the item you want, the highlight
will be moved to the first item that starts from that letter.
4.3.4 Drop-Down List Boxes
A drop-down list box appears initially as a rectangular box with the
current choice (default) displayed in the box. The arrow in a square box at
the right opens into a list of available choices when you select it. If
there are more choices than can fit in the drop-down list box, a scroll bar
is provided.
A selected drop-down list box can be opened without a mouse by pressing
ALT+DOWN ARROW. An opened drop-down list box is closed when you select an
item in it, select other option in the dialog box, or press ALT+DOWN ARROW.
4.3.5 Option Buttons
Option buttons appear in dialog boxes as a list of mutually exclusive
items. From the list you can select only one option a time. You can change
a selection by selecting a different button.
The selected option button contains a black dot.
To select an option button:
* Click it.
* Press TAB to move into the option group you want; then use the DIRECTION
keys to select the option button you want.
* Or, if the option name contains an underlined letter, you can hold down
ALT and press the underlined letter from anywhere in the dialog box to
select an option button.
In dialog boxes where all options are represented by option buttons, you
can double-click an option button to choose it and complete the command at
once.
4.3.6 Check Boxes
Check boxes offer a list of options you can switch on and off. You can
select as many or as few check box options as are appropriate. When an
option in a check box is selected, it contains X. Otherwise, the box is
empty.
To select or clear a check box option:
* Click the empty check box you want to select. Click a selected box again
to clear the selection.
* Press TAB to move to the empty check box you want to select. Press the
SPACEBAR to enter an X. Press the SPACEBAR again if you want to clear the
selection.
* Or, if the check-box name has an underlined letter, hold down ALT and
press the underlined letter for each check box you want to select or
clear.
4.4 Selecting Geometric Objects
When editing the model geometry or analyzing the results you may need to
enter the coordinates of a point. The plus sign cursor (+) arises to
indicate the point locating mode. This cursor can be moved by mouse or
using the DIRECTION keys. The HOME, END, PAGE DOWN and PAGE UP keys move
the cursor in four diagonal directions. You can control the keyboard cursor
step by the MINUS and PLUS keys. The MINUS key approximately halves the
cursor step, the PLUS key increases it back. You also can get very fine
cursor movement by holding down CTRL while pressing the DIRECTION keys.
To select a point of the model move the cursor to the position of choice
and click left mouse button or press the ENTER key. ESC or the right mouse
button cancels the operation. If you prefer numerical form of the
coordinates input press TAB and you will get a dialog box with two text
boxes for coordinates typing. Press ENTER or click the dialog box
background to complete the dialog and carry out the command.
When working with the model you often need to select some of its
constituent geometric objects. The picking mode is indicated by the X-
shaped cursor. You can move this cursor the same way as while locating a
point. To pick a massive object like a block place the center of the cursor
on that object and click the left mouse button or press the ENTER key. To
pick a vertex or an edge it is not necessary to point cursor exactly on the
object. The selected object is always the closest to the cursor.
4.5 Using Rubber Band Rectangle
The rubber band rectangle is used to zoom-in to a rectangular part of the
model or of an X-Y plot. The chosen part is enlarged to occupy the whole
available screen area. The rubber band rectangle is controlled using a
mouse or the DIRECTION keys. First, choose the position of the lower left
hand corner, then of the upper right hand one.
5. Problem Description
5.1 Structure of Problem Database
A special database is built for each problem solved with QuickField. The
core of the database is the problem description, which is stored in file
with the extension .PBM. The problem description contains the basics of the
problem: its subject, plane, precision class, etc., and also references to
all other files, which constitute the problem database. These files are the
model file, with standard extension .MOD", and physical data files, with
extension .DES, .DCF, .DMS, .DHE, .DHT, or .DSA", depending on the subject
of the problem.
The problem description may refer to one or two files of physical data.
Both files have the same format, and differ only in purpose. Usually, the
first data file contains specific data concerning the problem, as the
second file is a library of standard material properties and boundary
conditions, which are common for a whole class of problems.
Depending on the problem type, you may share a single model file or a
single data file between several similar problems.
While solving the problem, QuickField creates one more filesthe file of
results with the extension .RES. This file always has the same name as the
problem description file, and is stored in the same directory.
5.2 Creating a New Problem
To create a new problem, choose "New" in the "Files" menu (ALT+F, N), and
then enter the name of the new problem. While created, new problem inherits
settings of the preceding problem. To change these settings, choose
"Problem" in the "Edit" menu (ALT+E, P). The dialog box appears, containing
problem description options. Here you can pick the problem type, model type
(2D planar or axisymmetric), precision level, and etc.
To exit from problem description editing, choose "OK". You can cancel
editing by choosing "Cancel" button, or pressing ESC, or clicking right
mouse button.
Choosing the "Browse" button allows you to select a file from the list of
files and directories when defining the model or data filename. The button
acts on that type of file, which is currently selected.
Once the file is chosen, you can instantly open it for editing by choosing
the "Open" button. It acts upon the currently selected file. For example,
if you have selected geometry file, by choosing "Open", you would get into
the Model Editor.
5.3 Establishing Coupling Links
The stress analysis and heat transfer problems can incorporate data, which
come from other analysis types. The data types are: electrostatic and/or
magnetic forces and temperature field for the stress analysis, and power
losses generated by the current flow for the heat transfer.
To establish a link between the problem that imports data and the problem
that originates them choose "Imported Data" button in problem description
dialog box. The following dialog box will appear.
To add a data link:
1. Select the type of the data in the "Data Type" pull-down list box;
2. Type a name of the source problem in the "Problem" text box, or choose
"Browse" button to make the selection from the list of existing
problems;
3. And, choose "Add" button to add the link to the list of data sources.
To add a data link:
1. Select the type of the data in the "Data Type" pull-down list box;
2. Type a name of the source problem in the "Problem" text box, or choose
"Browse" button to make the selection from the list of existing
problems;
3. And, choose "Add" button to add the link to the list of data sources.
To change a data link:
1. Select the link of choice in the "Data Sources" list box;
2. Change the source problem name as necessary;
3. And, choose "Update" button to update the link in the list of data
sources.
To delete a link:
1. Select the link of choice in the "Data Sources" list box;
2. And, choose "Delete" button to delete the link from the list of data
sources, or use "Delete All" button to delete all data links at once.
The links to the imported data are considered to be a part of the problem
description. The changes made in them are preserved only if you choose "OK"
when completing the problem description editing. And, vice versa, if you
would choose "Cancel" button or press ESC, the changes made in data links
will be discarded along with other changes in problem description.
5.4 Choosing Length Units
QuickField allows you to use various units for coordinates when creating
model's geometry. You can use microns, millimeters, centimeters, meters,
kilometers, inches, feet, or miles. To set the units of preference, choose
"Length Units" from the "Options" menu (ALT+O, U).
Chosen units are associated with each particular problem, which gives you
freedom to use different units for different problems. Usually units of
length are chosen before creating the model geometry. It is possible to
change units of length later, but it does not affect physical dimensions of
the model. So, if you create your geometry as a square with 1 m side and
then switch to centimeters, you will get a square measured 100 cm by
100 cm, which is the same as it was before. To actually change size of the
model you should rather use "Scaling" option of the "Move Selected" command
of the Model Editor.
The choice of length units does not affect units for other physical
parameters, which always use standard SI units. E.g., the current density
is always measured in A/m2 and never in A/mm2. The only physical quantity
that is measured in chosen units of length, is the displacement vector in
stress analysis problems.
5.5 Cartesian vs. Polar Coordinates
Problem geometry as well as material properties and boundary conditions can
be defined in Cartesian or polar coordinate systems. There are several
places in QuickField where you can make choice between Cartesian and polar
coordinate systems. Using "Coordinates" option from the "Options" menu
(ALT+O, C) you can define the default coordinate system associated with a
problem. The same option is also available in the Model Editor and in the
Postprocessor. Definition of orthotropic material properties, some loads
and boundary conditions depends on the choice of the coordinate system. You
can choose Cartesian or polar coordinate system for each element of data
individually and independently from the default coordinate system
associated with the problem. This choice is available in the dialog boxes
of the Data Editor.
6. Model Geometry Definition
This chapter describes how to define the model geometry and build the mesh
using QuickField preprocessing utility-the Model Editor.
6.1 Terminology
Vertex, edge, and block are three basic types of geometric objects, which
the Model Editor operates with.
Vertex is a point on the plane with coordinates defined by the user or
calculated automatically as intersection of the edges. For each vertex you
can define the mesh spacing value and the label. The mesh spacing value
defines approximate distance between mesh nodes in the neighborhood of the
vertex. The label is used, for example, to describe a line source or load.
Edge is a line segment or a circular arc connecting two vertices. It can't
intersect any other edge of the region. If an edge being created contains
an existing vertex, two adjacent edges are created. New vertices are
automatically created in all points where new edge intersects the existing
ones and all intersected edges are split by these vertices. Edges can be
labeled, for example, to specify the boundary conditions.
Block is a continuous subregion with its boundary consisting of edges and
possibly isolated vertices. A block may contain holes which can be formed
by chains of edges or by isolated vertices. Each block has to be labeled to
describe material properties. Labels of the blocks are also used to define
distributed field sources. Unlabeled block is not included in calculation
of field even it is covered by the mesh. The mesh is created block by block
automatically or according to the mesh spacing value defined for particular
vertices.
The Label is a string of up to 16 characters length, which establishes the
correspondence between geometrical parts of the model and physical values
assigned to them. Any printable characters including letters, digits,
punctuation marks, space character are permitted, except for asterisk (*)
and question mark (?) characters. The label cannot begin with space
character; trailing spaces are ignored. Labels are case-sensitive.
The Mesh Spacing value defines an approximate element size around the
vertex. The mesh spacing parameter is associated with the vertex and
measured in the current units of length. By setting mesh spacing values in
some vertices you can control the mesh density and therefore the accuracy
of the solution.
6.2 How to Create a Model
Model development consists of three stages:
* Geometry description;
* Definition of properties, field sources and boundary conditions;
* Mesh generation.
To describe model geometry you define vertices and edges which form
boundaries of all subregions having different physical properties. You can
create vertices and edges; move, copy and delete any geometric objects
using the selection mechanism or one by one.
You define properties, sources and boundary conditions by means of
assigning labels to geometrical objects.
There are two options available for creating the finite element mesh for
your model:
* Fully automated method which generates a smooth mesh with a density based
on region's dimensions and sizes of geometrical details. This option does
not require any information from the user.
* The second method allows you to choose the mesh density. In this case you
need to define the spacing values at few vertices of your choice. Spacing
values for other vertices are calculated automatically to make the mesh
distribution smooth.
6.2.1 Starting and Quitting the Model Editor
To start the Model Editor, choose "Geometry" from "Edit" menu (ALT+E, G) or
while editing the problem description select the model filename and choose
"Edit" button.
The Model Editor uses interactive graphics. Two graphic windows are
displayed on screen permanently. The small window presents general view of
the problem region, while the large one provides a more detailed view.
Below the graphic windows is a prompt line. Upper right screen area is
normally occupied by the menu or a dialog box used for editing values and
labels.
The Model Editor has hierarchical structure of menus. Pressing ESC or right
mouse button causes returning to preceding menu level or quitting the Model
Editor in the main menu.
To quit the Model Editor select "Exit" from the main menu or press ESC
while in the main menu. You will be prompted to save the model.
6.2.2 Objects Selection
The Model Editor provides possibility to make some group operation upon
several objects at once if those have been previously selected. To enter
select mode, choose "Select" and then one of "Select Blocks",
"Select Edges" or "Select Vertices" in a dialog box that will appear.
While in select mode pick an object to select or unselect it. All selected
objects are highlighted on the screen. To leave the select mode press ESC
or right mouse button. Objects of different types cannot be selected
simultaneously.
"Unselect All" cancels all previous selections.
6.2.3 Geometry Description
Whenever a new model is created, the default window is set to correspond to
a unit square. For planar models the horizontal and vertical directions
correspond to X and Y axes, and. for axisymmetric models they correspond to
Z and R axes, respectively. It is convenient to assign the window with
region's dimensions and create the outward boundary of the model at once,
and then describe the details. To change default window dimensions choose
"Keyboard" from "Zoom" submenu. The default window dimensions are saved
with the model to be restored in later editing sessions.
To build the geometry of your problem go to "Model" submenu. First, you
need to create the vertices using the "Add Vertex" command. Locate the
required positions with the cursor or press TAB to enter coordinates from
the keyboard. New vertex appears in the window. Then you can continue
creating vertices or return to "Model" menu by pressing ESC or right mouse
button.
If at least two vertices are defined in the region you can connect them
with an edge. To do this, choose "Add Edge" and type in the angle size in
degrees for a new edge. Zero value corresponds to a line segment. Positive
value defines an arc directed from the first vertex to the second one
counter-clockwise, or clockwise if negative. After defining the angle size,
pick the vertices to be connected by the edge in corresponding order. New
edge appears in the window. Picking vertex by vertex you can create several
edges of the same angle size. To break the chain and start a new one, press
ESC. To return to menu press ESC twice.
6.2.4 Copying and Moving Geometric Objects
Repeated geometry elements can be easily created by means of copying any
set of objects to new location, using geometric transformations listed
below. To make a copy:
1. Select any number of objects (vertices, edges or blocks) you want to
copy, choosing "Select" from the menu.
2. Choose "Copy Selected". The dialog box appears, asking for copying
parameters.
3. Select transformation, enter its parameters and choose OK. The new
objects will appear on screen and the program will be waiting for your
confirmation, so you could be sure that you entered the parameters
correctly.
4. Choose "Create" to confirm copying. New objects will be `implanted' into
the model, and selection will move to the last copy.
The copy operation affects all explicitly set features of the selected
objects, including labels and spacing values. Only the mesh is not copied.
Caution. Use copy operation with care, because improperly set
transformation parameters may cause creating new objects in the
wrong places. Such improper objects may interfere with the existing
objects and generate a lot of useless intersection points, which
will be hard to remove later.
You can also move selected objects to other location with the restriction,
that region topology will not change, and no new intersection or coinciding
will arise. To move selected objects, choose "Move Selected" from the menu.
The dialog box which appears is very similar to "Copy Selected" dialog box.
Geometric transformations available with move and copy operations are:
Displacement - parallel displacement is applied to selected objects
for specified displacement vector. With copy operation, several
copies can be asked for, it means that copying operation will be
performed several times, each time being applied to the previous
result. Parameters needed are displacement vector components.
Rotation- selected objects are rotated around the specified point for the
specified angle. With copy operation, several copies can be asked
for, it means that copying operation will be performed several
times, each time being applied to the previous result. Parameters
needed are center of rotation coordinates and angle measured in
degrees.
Symmetry- selected objects are mirrored; symmetry line is specified by
coordinates of any point on it and the angle between the
horizontal axis and the symmetry line. Positive value of an angle
means counter-clockwise direction. This transformation is
available for copy operation only.
Scaling - selected objects are dilated (constricted) by means of homothetic
transformation. Parameters needed are center of homothety and
scaling factor. This transformation is available for move
operation only.
You can remove auxiliary or incorrectly defined vertices, edges and blocks
by choosing "Delete Selected", "Delete Vertex" or "Delete Edge". If the
vertex being removed contacts exactly two edges, which can be treated as
single edge when eliminating that vertex, those are joined together.
Otherwise confirmation will be asked to delete all the connected edges.
6.2.5 Labeling Vertices, Edges and Blocks
The correspondence between geometrical objects and their physical
properties, such as material properties, boundary conditions, or field
sources is established by the use of labels. All operation with assigning,
editing and checking the labels is done in the "Label" menu.
To assign a label, choose one of "Label Block", "Label Edge" or
"Label Vertex", and then pick the entity which you need to label. The
dialog box will appear, which allows you to type in the label from keyboard
or to select one from the previously defined labels in the model or in data
files assigned to the problem. After you define the label, you can continue
picking the objects or return to the menu by pressing ESC key.
You may assign the same labels to several entities of similar type at once.
To do so, first select those objects by using "Select" command (for more
details see the section on Object Selections) and then label them using
"Label Selected".
To check labels assignment or to select objects possessing the same label,
use "Find Label". The dialog box will appear, which allows you to select
the type of object, and contains the full list of labels as appear in the
model for the given object type. Picking some label in the list would
select all the objects associated with that label.
6.2.6 Building the Mesh
After creating the geometry of the model or its parts, you can proceed with
building the finite element mesh. With the Model Editor you can easily
build a nonuniform mesh for a highly complex geometry. You may choose a
fine mesh in some regions and very coarse in others, since the geometric
decomposition technique would produce a smooth transition from large to
small element sizes. Generally, the mesh has to be fine where the field
changes most rapidly (high gradient), and also where you need high
precision.
If the geometry is rather simple, or a draft precision for preliminary
design analysis is satisfactory, it is suggested to use the fully automatic
mode to create the mesh. With this option, once you built your geometry you
would simply choose "Build Mesh" and a suitable mesh is automatically
created without any information on the mesh size.
You also have the option to pick the mesh density if you choose to do so.
The mesh density is controlled by spacing values in vertices. The spacing
value defines approximate distance between mesh nodes around that vertex.
You never need to define the spacing in all model's vertices. To obtain
uniform mesh you can set the spacing in any one vertex. This value is
spread among all other vertices automatically. If you need the non-uniform
mesh, define spacing values only in those vertices where you need finest
and roughest mesh. The spacing values are automatically interpolated to
other vertices to smooth the mesh density distribution. The group selection
mechanism allows to assign the value to several vertices at once.
After defining spacing values, you can proceed with the mesh building. The
mesh is built block by block. You may choose to build the mesh in one block
or in selected blocks or in entire region at once.
Changing the density of a pre-built mesh (e.g. if solution results show
that you need more precision somewhere in the region) obey some rules:
* When you change the spacing value in some vertex, the mesh is removed
automatically in those blocks which are connected to that vertex.
* The mesh that is not removed, freezes spacing values along its boundary
from recalculation as if those values were defined manually; so if you
need major changes in the mesh density, first remove the mesh in the
whole region.
All operation with spacing values and the mesh is performed in the "Mesh"
submenu. To define the spacing, choose "Set Spacing", then pick the vertex
and type in the spacing value. Then you can alter spacing at any other
vertex or return to menu by pressing ESC. If there are some previously
selected vertices, the spacing values are set for all of them at once. If
some edges are selected, the spacing values are set for all the vertices
located on them. The same way, if there are some selected blocks, the
spacing values are set for all the vertices located on their boundaries or
inside them.
To build the mesh, choose "Build Mesh" and select an option. "Delete Mesh"
removes mesh in some blocks or in the entire region.
If the spacing visibility switch is on ("Show Spacing" in the "Options"
menu), the explicitly set spacing values are shown as small circles around
the vertices. You can see the mesh building process if "Show Mesh" toggle
in the "Options" menu is on.
6.2.7 Zooming
There are two graphic windows on the screen while editing the model. The
small window always displays the general view of the model. The large
window is used to present a more detailed picture of the whole model or its
selected parts. "Zoom" menu provides several options to control the
displays in each graphic window.
"Keyboard" allows you to type in dimensions of the visible region.
Specified region is displayed in both windows and becomes the default. This
is a normal way to extend the default visible region. Limits of the visible
region can be automatically adjusted to preserve equal horizontal (X or Z)
and vertical (Y or R) scales.
"Natural" sets minimum visible region large enough to contain the whole
model. Resulting region is displayed in both windows and becomes the
default.
"Default" sets visible region dimensions to the default values. The region
visible in the large window becomes the same as in the small one.
"Large Window" controls the dimensions of the visible region using rubber
band rectangle in the large window. The rubber rectangle is controlled
using mouse or cursor keys. First, choose position of the lower left hand
corner, then of the upper right hand one.
"Small Window" does the same, but rubber band rectangle appears in the
small window. This mode is recommended when whole or part of the required
region lies outside the large window.
6.2.8 Obtaining Model Information
You can get detailed information on the current model using "Info" submenu.
In this submenu choose the object type (vertices, edges or blocks) and
complete information corresponding to that type will be displayed (amount
of objects, presence of labels, mesh parameters, etc.). Then you can pick a
specific object within that group to get more local information. Pressing
ESC returns to the menu. This mode is used to get total number of mesh
nodes, to check labels, to examine the mesh spacing values and so on.
6.3 Additional Options
6.3.1 Saving Model
The "Save" command of "File" menu saves the model to disk. The "Save As"
does the same but lets you change the name of output file. It is wise to
save model not only when editing is over, but regularly during the session
to avoid troubles due to errors or power failure.
Note. When the "Save As" command changes name of the model file it
automatically updates reference to the model file in problem
description.
6.3.2 Opening Model File
To create new empty model choose "New" in the "File" menu. To open existing
model file choose "Open" in the same menu, and then type or select the file
name. If the active model was changed you will be prompted to save it
before transition to the new one.
With "Open", you can import old geometry model files created with the 1.x
or 2.x versions of QuickField and having ".TRI" extension. To do so, you
need only to specify ".TRI" extension when selecting the file.
Note. While loading old-formatted model, all numerical labels are
transferred to literal form automatically.
6.3.3 DXF File Import
You can import model geometry or its fragments from the DXF file produced
by any major CAD system. To do so, choose "Import DXF" in the "File" menu
and then type or select required file name. The visible region is
automatically extended if needed to assure visibility of all imported
geometric objects. If the model is not empty when reading the DXF file, it
is recommended to save the current model state before the operation. This
will give you a chance to return to the initial stage if the imported
objects incidentally overlap the existing part of model.
6.3.4 Discretization Visibility Options
There are four switches "Show Mesh", "Show Domain", "Show Breaking", and
"Show Spacing" which affect the discretization visibility level. These are
accessible through "Options" menu. When all these switches are off, region
is displayed without discretization. This mode is useful for region
geometry description and label setting. If the "Show Spacing" mode is
switched on, all explicitly set spacing values are shown as circles with
the appropriate radii.
When "Show Breaking" switch is on, the size of the elements along the edges
is shown as tic marks on the edges. It is convenient to use both
"Show Spacing" and "Show Breaking" when specifying the mesh spacing values.
"Show Mesh" lets you see the complete triangular mesh. Turn it on to check
the mesh building process. "Show Domain" without "Show Mesh" displays the
domains due to geometric decomposition process.
The state of these switches is remembered between sessions.
6.3.5 Attraction Distance Parameter
To avoid small unrecognizable inaccuracies in geometry definition, new
vertices or edges cannot be created very close to the existing ones. The
creation of new geometric objects is controlled by the e parameter also
called the attraction distance.
The following rules concern creating new vertices and edges.
* Creating a new vertex is prohibited within 2*epsilon-neighborhood of the
existing one.
* A new edge cannot be added if it joins the same vertices as of an
existing edge and the maximum gap between them does not exceed epsilon.
* If the distance between a vertex to add and some edge is less than or
equal epsilon, the vertex is attracted by the edge and the edge is
automatically split into pair of new edges to incorporate the vertex. The
same is true when new edge is added, but in this case the new edge may be
attracted by existing vertex.
The default value of epsilon is 0.5 per cent of the visible region size.
You can set different value by choosing "Epsilon" in "Options" menu.
Decreasing epsilon would allow you to describe very fine details of the
model. But the most convenient way to get the same result is to zoom in the
window.
7. Problem Parameters Description
To solve the problem it is needed to describe the material properties,
field sources and boundary conditions. These parameters are stored in the
property description file. The correspondence between records of these
files and subdomains or boundaries of the region is established by the
labels assigned to geometrical objects during editing the model. Labeling
blocks, edges and vertices is described in Chapter 5 "Model Geometry
Definition".
Physical values for a problem may be defined in one or two data files
attached to the problem. Both files have the same format and distinguish
only in purpose. The first file is the basic data file of the problem and
is assumed to contain the data specific to that problem. The second is the
library file, that contains common material properties and standard
boundary conditions for a class of problems.
To edit the basic data file, choose "Data" in the "Edit" menu (ALT+E, D) to
edit the library file, choose "Library" (ALT+E, L.) The alternate method
to start editing data is to select the name of one of the data files and to
choose the "Open" button while editing the problem description.
When entering data file editing mode, the dialog box appears, containing
three lists of labels, which correspond to blocks, edges and vertices.
Option buttons above the list boxes, allow you to choose the label group
type. Once you pick a label from the available lists, it gets highlighted.
In this case it appears also in the text box below the list boxes. The
label in the text box is the current label, so all the immediate actions
are done to this label.
The labels with no specified data are marked with asterisks. Labels of the
blocks which are excluded from consideration (i.e., having empty material
properties,) are marked with double exclamation mark.
Options for editing the data file could be divided into three groups. The
first group considers actions on creating new labels and editing data for
existing ones. Operations on copying, renaming and deleting a data set
associated with the label belong to the second group. The third group
includes saving the data file under another name and merging two data
files.
To exit from data file editing, choose the "Close" command button or press
the ESC key. You will be prompted to save the changes to file.
7.1 Creating a New Label
To create a new label:
1. Choose appropriate type of geometric objectsblock, edge or vertex;
2. Type the name of the label in the text box titled "Label". You may use
the INS key in addition to usual methods to move to the text box. If the
label's name already exists in the list, but is marked with asterisk
(which means that the data for the label is not defined yet) you need
not type the name, but simply select it in the list using keyboard or
mouse;
3. Choose "Add" button or press ENTER to start editing the data.
After you define the data, new label appears in the list of existing
labels. If data editing was canceled, new label is not created.
7.2 Editing Label Data
To edit the data associated with some label, select that label and choose
"Edit" button or press ENTER. The dialog box appears, its view depends on
the class of current problem and on the type of geometrical object which
the label corresponds to.
To finish label data editing, choose "OK" button. Choosing "Cancel" button
will end the editing and discards all changes to the values.
7.2.1 Editing Data in Magnetostatics
With problems of magnetostatics, block label data contain two components of
magnetic permeability tensor, the current density, and for permanent
magnets also magnitude and direction of coercive force.
With nonlinear materials, you need to define the magnetization curve,
instead of magnetic permeability. In this case check the "Nonlinear" box to
get into the B-H curve editor. If a B-H curve had already been defined, the
dialog box would contain a "B-H Curve" button which can be chosen to get
into the curve editor. Editing the magnetization curve is discussed in
"Editing the Curves" section later in this chapter.
When creating data for a new label, the text boxes for magnetic
permeability components contain None" instead of numbers. The word None" in
these boxes or absence of value means that the block with such label is
excluded. If you want to define the material properties (and therefore
include the block into consideration), simply type in the value of magnetic
permeability, which will replace the highlighted None".
If you need to define two components different from each other, first check
the "Anisotropic" box.
The data for the edge label allow to assign one of possible boundary
conditions. Select the type of condition and then type in the values.
The vertex in the problem of magnetostatics may have known potential or the
concentrated current may flow through the vertex. Check one of the options
and then enter a value.
7.2.2 Editing Data in Harmonic Magnetics
With problems of harmonic magnetics, block label data contain two
components of magnetic permeability tensor, electric conductivity and one
of three possible field sources: source current density, voltage, or total
current.
When creating data for a new label, the text boxes for magnetic
permeability components contain None" instead of numbers. The word None" in
these boxes or absence of value means that the block with such label is
excluded. If you want to define the material properties (and therefore
include the block into consideration), simply type in the value of magnetic
permeability, which will replace the highlighted None".
If you need to define two components different from each other, first check
the "Anisotropic" box.
The method of applying sources is different for conductors and non-
conductive areas. In first case, you may switch between voltage and total
current, as in second case voltage is inaccessible and you can apply
current density or total current only.
Note. It is assumed that total current specified for some data
label is a summary current in all blocks carrying that label.
With harmonic problems, you always specify amplitude, or peak, values for
all alternating quantities.
The data for the edge label allow to assign one of possible boundary
conditions. Select the type of condition and then type in the values.
The vertex in the problem of harmonic magnetics may have known potential or
the concentrated current may flow through the vertex. Check one of the
options and then enter a value.
7.2.3 Editing Data in Electrostatics
Block label data for electrostatics problem contain two components of
electric permittivity and possibly distributed charge density.
When creating data for a new label, the text boxes for electric
permittivity components contain None" instead of numbers. The word None" in
these boxes or absence of value means that the block with such label is
excluded. If you want to define the material properties (and therefore
include the block into consideration), simply type in the value of electric
permittivity, which will replace the highlighted None".
If you need to define two components different from each other, first check
the "Anisotropic" box.
The data for the edge label allow to assign one of the possible boundary
conditions. Select the type of condition and then type in the values.
The vertex in the problem of electrostatics may have known potential or
concentrated charge. Check one of these options and then enter a value.
7.2.4 Editing Data with Current Flow Problems
Block label data for the problem of current flow contain two components of
electric resistivity.
When creating data for a new label, the text boxes for electric resistivity
components contain None" instead of numbers. The word None" in these boxes
or absence of value means that the block containing such label is excluded.
If you want to define the material properties (and therefore include the
block into consideration), simply type in the value of electric
resistivity, which will replace the highlighted None".
If you need to define two different components of resistivity, first check
the "Anisotropic" box.
The data for the edge label allow you to assign one of possible boundary
conditions. Select the type of condition and then type in the values.
The vertex in the problem of current flow may have known potential or
external current. Check one of these options and then enter a value.
7.2.5 Editing Data with Heat Transfer Problems
The data for block label contain two components of thermal conductivity
tensor and, possibly, the volume power of heat source.
To describe the thermal conductivity as a function of temperature, check
the "Nonlinear" box and the temperature curve editor for defining
"lambda = f(T)" will be displayed. Curve editing is discussed in "Editing
the Curves" section later in this chapter.
Also the volume power of heat source could be described as a function of
temperature. To do so, check the "Function of Temperature" box related to
the heat source field. Editing the dependencies is described in "Editing
the Curves".
When creating new label, the text boxes for thermal conductivity components
contain None" instead of numbers. The word None" in these boxes or absence
of value means that the block containing such label is excluded. If you
want to define the material properties (and therefore include the block
into consideration), simply type in the value of thermal conductivity,
which will replace the highlighted None".
If you need to define two different components of thermal conductivity,
first check the "Anisotropic" box.
The data for edge label allow you to describe boundary conditions. Check
the condition which you need, and then type in the parameters. The heat
flux, convection, and radiation can be combined together, which means that
the heat flow through the surface is compounded from several components.
The vertex in heat transfer problem may have known temperature, or
represent a line heat source. Check one of these options, and then enter
the numeric parameter.
7.2.6 Editing Data with Stress Analysis Problems
When editing the data for the block label with stress analysis problem,
there are two sets of properties to be edited simultaneously. To switch
from one set to another, use option buttons at the top of dialog box or
press PAGE UP or PAGE DOWN keys.
When creating new label, the text boxes for Young's moduli contain None"
instead of numbers. The word None" in these boxes or absence of value means
that the block containing such label is excluded. If you want to define the
material properties (and therefore include the block into consideration),
simply type in the value of the Young's modulus, which will replace the
highlighted None".
The "Anisotropic" boxes, which applied to elastic moduli or coefficients of
thermal expansion, allow you to describe anisotropic properties in each set
independently.
The data for thermal loading are defined slightly different way for thermo-
structural coupled and non coupled problems:
* With an uncoupled problem, you define the temperature difference between
strained and strainfree states, which is assumed to be constant within
all blocks with the corresponding label.
* With thermo-structural coupling, you need to define the temperature of
strain free state for each block subjected to thermal loading.
The values of allowable stresses do not affect the solution. Those are only
used in postprocessing stage to calculate the Mohr-Coulomb, Drucker-Prager,
and Hill criteria. You don't need to define allowable stresses, if these
criteria are of no interest to you.
The data defined for an edge label may include constraints along one or
both coordinate axes and the surface forces are described either as normal
pressure or by their Cartesian or polar coordinate system components. To
apply fixed displacement along an axis, check the appropriate box and then
enter a value of displacement.
The vertex label data may define rigid or elastic support along one or both
coordinate axes, or concentrated external force. To describe rigid
constraint along some axis, check the appropriate box, and then enter the
value of fixed displacement.
7.2.7 Editing the Curves
Curve functions, which describe some field dependent parameters, are
implemented as tables containing two columns: an argument and a function,
e.g., magnetic field intensity and flux density or temperature and thermal
conductivity. Editing the table is supported with graphical presentation of
the dependency, which is interpolated with cubic spline between the entered
points. The solver uses just the same curve as you see on your screen.
To add the new point to the dependency, type in two values (B and H in
shown example) and press ENTER key or choose "Add" button. If the argument
of a new point coincides with the argument of existing one, new point
replaces the old one.
To remove the point, select it in the table and choose "Delete" button or
press the DEL key.
You may control the scaling of the graph with use of "Zoom In" or "Zoom
Out" buttons.
To exit from editing the curve, choose "Close" button or press ESC. Note
that subsequent canceling of label data editing with ESC key or the
"Cancel" button will discard all changes including the curve editing.
7.3 Copying, Renaming and Deleting Labels
In order to copy or rename a label (to be precise, a data set related to
the label), select the label in the list and choose "Copy" or "Rename"
button. A new name is entered in a dialog box, which appears when you
choose the button.
To remove a label, select it and choose "Delete" or press DEL.
7.4 Merging and Copying Data Files
"Merge" command button allows you to expand the contents of the data file
being edited with the labels contained in some other data file for the same
type of problem. The labels with coinciding names will not be replaced.
8. Solving the Problem
This chapter describes, how to solve the prepared problem, and methods
QuickField uses to solve.
Several conditions have to be met to solve a problem. The problem type,
plane, required precision and other parameters have to be specified in the
problem description file. The model geometry file must contain complete
model with mesh and labels. Each label referred by the model file is to be
defined in the problem's private or library data file.
To obtain the problem solution, choose "Solve Problem" from the "Results"
menu (ALT+R, S). You may skip this action and directly proceed to the
analysis results by choosing "Analyze" from the "Results" menu (ALT+R, A).
If the problem has not been solved yet, or its results are out of date, the
solver will be invoked automatically.
Special bar indicator lets you see the progress of the solution process.
Linear problems are solved by using a powerful preconditioned conjugate
gradients method. The preconditioning based on the geometric decomposition
technique guaranties a very high speed and close to linear dependence
between number of nodes and the resulting solution time. Nonlinear problems
are solved using the Newton-Raphson method. The Jacobian matrix arising at
each step of the Newton-Raphson method is inverted the same way as it is
done for linear problems.
9. Analyzing Solution
This chapter explains the procedures for detailed examination of the
results using the QuickField postprocessing utility. The Postprocessor
provides various ways of results presentation:
* field pictures,
* local field values,
* integral quantities,
* X-Y plots.
Field pictures and X-Y plots can be saved in vector-formatted files for use
with any word-processing or desktop publishing utility. Local field values
and sequences of points from X-Y plots can be stored in table files for
subsequent use by spreadsheet or user-written programs.
9.1 Starting and Quitting the Postprocessor
To examine the results, choose "Analyze" from the "Results" menu (ALT+R,
A).
Screen layout when working with the Postprocessor is very similar to one of
the Model Editor. There are two graphic windows displayed on the screen.
The small one presents general view of the model, while the large one shows
detailed field picture or an X-Y plot. The message bar is at the screen
bottom edge. Upper right screen area is normally occupied by menu, legend
box, or a temporary window used to display text information.
To quit the Postprocessor select "Exit" from its main menu, or press ESC
while in the main menu.
9.2 Building the Field Picture on the Screen
9.2.1 Interpreted Quantities
The set of the physical quantities which can be displayed by the
Postprocessor depends on the problem type.
9.2.1.1 For the electrostatic problem these quantities are:
* scalar electric potential (voltage) U;
* vector of electric field intensity E = - grad(U);
* tensor of gradient of electric field G = grad(E);
* vector of electrostatic induction D = epsilon * E;
* electric permittivity e (or its largest component in anisotropic media);
* electrostatic field energy density w = (E*D)/2.
9.2.1.2 For the magnetostatic problem:
* vector magnetic potential A in plane-parallel problem or flux function
Phi = 2*PI*rA in axisymmetric case;
* vector of magnetic flux density B = curl (A);
* vector of magnetic field intensity H = (1/mu)*B;
* magnetic permeability mu (its largest component in anisotropic media);
* magnetic field energy density:
w = (B*H)/2 s in linear media,
w = Integral(H*dB) s in ferromagnetic media.
9.2.1.3 For the problem of harmonic magnetics:
* complex amplitude of vector magnetic potential A (flux function rA in
axisymmetric case);
* complex amplitude of voltage U applied to the conductor;
* complex amplitude of total current density j = j0 + jeddy, source current
density j0 and eddy current density jeddy = -I*omega*g*A.
All these complex quantities may be shown in form of momentary, root mean
square (RMS) or peak value in time dimension.
E.g., complex quantity z = z0*exp(i*(omega*t + phiz)) my be shown as:
* momentary value at given phase phi0 = omega*t0
z = Re (z0*exp(i*(phi0+phiz)) = z0*cos(phi0+phiz);
* peak value z0;
* RMS value
z = sqrt(2)/2 * z0.
* Complex vector of the magnetic flux density B = curl (A)
* complex vector of magnetic field intensity H = (1/mu)*B, where mu is the
magnetic permeability tensor.
Complex vectors may be shown in form of momentary, RMS or peak magnitude.
* Time average and peak Joule heat density Q = (1/g)*j*j;
* time average and peak magnetic field energy density w = (B*H)/2;
* time average Poynting vector (local power flow) S = [E, H] (cross product
E and H);
* time average Lorentz force density vector F = [j, B];
* magnetic permeability mu (its largest component in anisotropic media);
* electric conductivity g.
9.2.1.4 For the problem of current flow:
* scalar electric potential U;
* vector of electric field intensity E = - grad(U);
* vector of current density j = (1/ro)xE;
* electric resistivity ro (its largest component in anisotropic media);
* ohmic losses per volume unit w = (j*E)/2.
9.2.1.5 For heat transfer problem:
* temperature T;
* vector of heat flow F = -lambda * grad(T);
* thermal conductivity lambda (its largest component in anisotropic media).
9.2.1.6 For stress analysis problem:
* displacement vector delta;
* strain tensor epsilon and its principal values;
* stress tensor sigma and its principal values;
* von Mises stress (stored energy of deformation criterion)
* Tresca criterion (maximum shear)
* Mohr-Coulomb criterion
* Drucker-Prager criterion
* Hill failure index for orthotropic materials
The Hill failure index is calculated only for those materials, where
allowable stresses were defined (while editing the block data, see
"Problem Parameters Description"). If any pair of allowable stresses is
not given, the corresponding term is dropped while calculating the Hill
Index.
9.2.2 Field Presentation Methods
Several methods are available for displaying the field picture:
* Color map for distribution of a chosen scalar quantity. The color map is
accompanied by the legend showing the correspondence between colors and
numerical values.
You can adjust the color scale by changing the range limits for the
chosen quantity.
* Field lines. Those are isotherms for temperature fields, lines of equal
potential in electrostatics and flux lines for magnetostatic problems.
You can manipulate the picture by changing the distance between
neighboring lines. This distance is measured in units of chosen quantity.
* Vectors-family of line segments showing magnitude and direction of the
vector quantity. The base point of each vector is marked by a dot.
Vectors are drawn in the nodes of the regular rectangular grid.
You can change the grid cell size and the scaling factor for a desired
vector quantity.
The following methods are specifically for stress analysis problems:
* Deformed boundary and shape indicated by means of deformed and original
rectangular grid.
* Stress tensor display as a pair of eigenvectors reflecting the direction
of principal axes, magnitudes and signs of principal stresses (blue color
denotes tension, red color-compression);
With these methods, you can change the grid cell size and the scaling
factors in order to manipulate the appearance.
It is possible to combine several visualization methods in the same picture
to obtain the most expressive result.
9.2.3 Field Picture Constructing
When entering the Postprocessor, the default form of the field picture
appears on the screen. You may use "Field View" from main menu to select
other display methods or quantities.
Shown dialog box corresponds to the problem of magnetics.
To choose desired visualization method, select corresponding check box. You
can select any combination of methods at once. If none of the methods is
selected, only the model's geometry is shown.
This dialog box also allows to change scaling parameters for selected
methods of presentation. When you select some edit box, you can choose
"Suggest" button to obtain suggested value of corresponding parameter. Note
that suggested values for "Minimum" and "Maximum" fields are calculated for
the currently visible part of the model.
In case of harmonic magnetics problem, equilines and vectors are drawn at
specified phase. The "Field View" dialog box allows to set phase value. For
more expressive field picture, you can order the second family of equilines
or vectors, shifted with regard to the first by 90..
The "Field View" dialog box for the stress analysis problem additionally
allows to select tensor quantity visualization.
Selecting the "Deformed Shape" option turns on "Deformed Boundary"
automatically.
Sizes of the vector symbols for all vector quantities except the
displacement vector are determined by the corresponding physical value
multiplied by the scaling factor and by the cell size. Similar method is
used for stress tensor components. Unlike other vector quantities, the size
of the displacement vector on the screen does not depend on the cell size.
It is determined by the dimensionless scaling factor, the unit value of
which means that the displacement is shown in its natural scale.
Color map of temperature difference in stress analysis problem visualizes
temperature distribution as it is defined by user or imported from linked
heat transfer problem. In the last case, temperature is shown only in those
blocks, where it is really taken into account.
The "Failure Index" option is available when the model contains at least
one block with correctly defined allowable stresses.
Choosing the "OK" button causes redrawing the field picture on the screen.
"Cancel" closes the dialog box without redrawing the picture and preserves
preceding values of all the parameters.
9.2.4 Zooming
To adjust the scale of the field picture, choose "Zoom" from the menu. This
command is very similar to the analogous command of the Model Editor, but
the default window dimensions cannot be altered, they retain values set in
the Model Editor.
"Keyboard" allows you to type in dimensions of the visible region. Limits
of the visible region can be automatically adjusted to preserve equal
horizontal (X or Z) and vertical (Y or R) scales.
"Default" sets visible region dimensions to the default values. The region
visible in the large window becomes the same as in the small one.
"Large Window" controls the dimensions of the visible region using rubber
band rectangle in the large window. The rubber rectangle is controlled
using mouse or cursor keys. First, choose position of the lower left hand
corner, then of the upper right hand one.
"Small Window" does the same, but rubber band rectangle appears in the
small window. This mode is recommended when whole or part of the required
region lies outside the large window.
"Maximize" enlarges the large window to the full screen for hard copying
and taking photos. Pressing any key returns the Postprocessor to its
preceding state. The color map legend could be shown in maximized view. To
switch legend on or off, choose "Show Legend" in "Options" menu before
maximizing.
9.3 Access to Local Field Data
The Postprocessor displays local field data in "Values" mode. Click the
point where you need to know the values of the field quantities, or press
TAB and then enter the coordinates of the point with the keyboard. Once you
choose the point, the values at this point are displayed on the screen. To
leave the "Values" mode use ESC key, or press right mouse button.
While analyzing harmonic magnetics field, you can choose between momentary,
time average, peak or complex form of time dependent field data.
Corresponding dialog box appears on the screen right after you choose the
"Values" mode.
The local values of physical quantities obtained in the "Values" mode can
be logged to the table file. This file has self explaining ASCII format,
with values separated with spaces or commas. The table file can be used for
printing numerical results, or to pass them to other application program,
e.g., a spreadsheet program to produce a report. To open the table file
choose "Open Table" from the "Options menu. See section "Exporting Local
Values to the Table File" for further explanation.
9.4 X-Y Plots
With QuickField Postprocessor, you can analyze field quantities
distribution along user-defined paths of arbitrary shape (contours).
Contours are also used for calculating integral quantities (see
"Calculating Integrals" later in this chapter) and for saving local field
values to the table file (see "Exporting Local Values to the Table File").
To start this mode, choose "X-Y Plot" from the menu. If the contour is
already defined, X-Y plot is immediately shown in the large window.
Otherwise you should define the contour, choosing "Edit Contour" from the
menu.
9.4.1 Editing Contours
The contour is a directed curved line consisting of line segments and arcs
(including the edges of the model). Some rules are applied to the contours:
* The contour may not intersect itself.
* Open and closed contours are discerned.
* Multiply connected contours have sense only for calculating integral
quantities.
Contour is shown in the window as a set of directed lines or color-filled
interior (closed counter-clockwise-directed contours).
To edit the contour, choose "Edit Contour" from the menu. The following
operations change the current contour state:
"Add Line" - attaches a line segment or an arc to the contour. The arc is
specified by its degree measure (zero means line segment)
and two end points. The contour may be initiated by an
arbitrary line, but only adjacent lines are accepted later.
The line cannot be added to the closed contour. Adding lines
is terminated by pressing ESC or when the contour becomes
closed.
"Close Contour" - closes an open contour by connecting its open ends
with a straight line or an arc.
"Add Edge" - append the contour with an edge of the model. The contour
may be initiated by an arbitrary edge, but only adjacent
edges are accepted later. The edge cannot be added to the
closed contour. Adding edges is terminated by pressing ESC
or when the contour becomes closed.
"Add Block" - considers the current closed contour as a border of the
plane region and updates this region by adding (or
subtracting) a block of the model in the sense of set
theory. Adding blocks is terminated by pressing ESC.
"Undo" - reverses the last action done with the contour.
"Clear" - deletes the entire contour.
"Change Direction" - alters the contour direction. The direction is
shown by the arrows at the contour elements.
Once edited, the state of the contour is preserved until the next
modification or the end of postprocessing session. Depending on current
state of the contour, some editing operations may be prohibited.
The direction of the contour is significant in the following cases:
* for volume integrals the domain of integration lies to the left of the
contour.
* for surface integrals the positive normal vector points to the right
relative to the contour direction.
* the starting point of the contour corresponds to zero point at the x-axis
of the X-Y plot.
* if the plotted or the integrated function has different values to the
left and to the right of the contour, the right-hand value is used.
9.4.2 X-Y Plot Control
Once the contour has been defined, the X-Y plot is drawn showing
distribution of the default field quantity. In order to change shown
quantity, choose "View" from "X-Y Plot" menu.
Few quantities having the same unit of measurement can be shown at the same
X-Y plot. According to this, all quantities are combined into groups. Full
list of quantities includes all those available for the color map
representation (see "Interpreted Quantities"), and also normal and
tangential components of vector and scalar quantities.
When you select the appropriate group of quantities, the list titled "Show"
contains the quantities selected for display, and the "Quantities" list
contains available but not selected quantities. You can use buttons located
between the lists, or simply double-click in the lists, to move some
quantity from one list to another.
In the dialog box, you can also modify the range of y coordinate. By
default, it fits all the currently selected curves. You can get the
suggested value of lower or upper limit by selecting the corresponding text
box ("Minimum" or "Maximum") and choosing "Suggest" button.
With the problems of harmonic magnetics, you can also switch between
momentary (at given phase), time average and peak values of time dependent
quantities.
You can turn on or off the switches for displaying coordinate grid and
markers on the curves. The last mode allows you to distinguish the
coinciding curves.
9.4.3 Zooming the X-Y Plot
"Zoom In" position in "X-Y Plot" menu allows you to change the plot
scaling, using the rubber band rectangle. Then you can return to the
default ranges for both axes, choosing "Zoom Out".
Choosing "Maximize" enlarges the X-Y plot window to the full screen
dimensions without changing axes ranges. Then press any key to return the
Postprocessor to its normal state. The legend is shown in maximized view,
if "Show Legend" in "Options" menu has been switched on earlier.
9.5 Calculating Integrals
QuickField calculates line, surface and volume integrals. In plane-parallel
problem, a contour defines cylindrical (in generalized sense) surface of
infinite depth, or volume of that cylinder for volume integral. Therefore,
in plane-parallel formulation surface and volume integrals are calculated
per unit depth. In axisymmetric problem, a contour defines toroidal
surface, or toroid for volume integral.
Positive direction of a contour is counter-clockwise. The direction of the
contour is accounted as follows:
* For volume integrals the domain of integration lies to the left of the
contour.
* For surface integrals the positive normal vector points to the right
relative to the contour direction.
* If the plotted or the integrated function has different values to the
left and to the right of the contour, the right-hand value is used.
Force, torque and electric charge integrals represent real physical
quantities only when the contour is closed. However, these integrals are
calculated for the unclosed contours too, commented as part.
To get the integral quantities, choose "Integrals" from the menu.
Choose "Edit Contour" button first to create a contour of integration. Some
integrals require closed counter-clockwise oriented contour, otherwise they
have no physical sense. Once you created the contour, you can select an
integral quantity from the list and choose "Calculate" button to get the
value. "Copy to File" button allows you to record the calculated result
into a text file.
When the electrostatic or magnetic force, torque, electric charge, electric
current or heat flux are to be calculated, the domain of integration may be
chosen by many different ways. The only requirement for the surface of
integration is to contain all the necessary bodies, but to avoid any extra
bodies or field sources. It is important to understand that the accuracy
will be the best if you choose the integration surface as far as possible
from the places with strong inhomogeneity of field, e.g., field sources or
boundaries of conducting or ferromagnetic bodies.
When calculating the flux linkage the domain of integration must exactly
fit the cross section of the coil.
9.5.1.1 The quantities available for electrostatic problems:
* Total electric charge in a particular volume
* Total electrostatic force acting on bodies contained in a particular
volume
* Total torque of electrostatic forces acting on bodies contained in a
particular volume
The torque vector is parallel to z-axis in planar case, and is
identically equal to zero in axisymmetric one. The torque is considered
relative to the origin of the coordinate system. The torque relative to
any other arbitrary point can be obtained by adding extra term of
[F , r0] (cross product F and r0), where F is the total force and r0 is
the radius vector of the point.
* Electric field energy
9.5.1.2 For magnetostatic problems:
* Total magnetostatic force acting on bodies contained in a particular
volume
* Total torque of magnetic forces acting on bodies contained in a
particular volume
The torque vector is parallel to z-axis in the planar case, and is
identically equal to zero in the axisymmetric one. The torque is
considered relative to the origin of the coordinate system. The torque
relative to any other arbitrary point can be obtained by adding extra
term of [F , r0], where F is the total force and r0 is the radius vector
of the point.
* Magnetic field energy
* Flux linkage per one turn of the coil
9.5.1.3 For harmonic magnetics problems:
* Complex magnitude of electric current through a particular surface, and
also its source and eddy components I0 and Ie.
* Time average and peak Joule heat in a volume
* Time average and peak magnetic field energy
* Time average and peak power flow through the given surface (Poynting
vector flow)
* Time average and oscillating part of Maxwell force acting on bodies
contained in a particular volume
* Time average and peak Maxwell force torque acting on bodies contained in
a particular volume
* Time average and oscillating part of Lorentz force acting on conductors
contained in a particular volume
* Time average and peak Lorentz force torque acting on bodies contained in
a particular volume
The torque vector is parallel to z-axis in the planar case, and is
identically equal to zero in the axisymmetric one. The torque is
considered relative to the origin of the coordinate system. The torque
relative to any other arbitrary point can be obtained by adding extra
term of [F , r0], where F is the total force and r0 is the radius vector
of the point.
Note. The Maxwell force incorporates both force acting on
ferromagnetic bodies and Lorentz force, which acts only on
conductors. If the first component is negligible or is not
considered, we recommend calculating the electromagnetic force as
Lorentz force. Its precision is less sensitive to the contour path,
and you can simply select conductors via block selection to
calculate the force. With Maxwell force, this method leads to very
rough results, and you need to avoid coinciding of your contour
parts and material boundaries, as described earlier in this
chapter.
9.5.1.4 For problems of current flow:
* Electric current through a given surface
* Power losses in a volume
9.5.1.5 For heat transfer problems:
No integral quantities are available for stress analysis.
9.6 Saving Prepared Results to Files
9.6.1 Saving the Screen Picture
The postprocessor is capable of storing current field picture or X-Y plot
in widely supported graphics file formats. Graphic objects in these files
are stored in vector form, independent of output device resolution. It
guaranties maximum quality pictures on different printers. These files can
be directly printed, as well as included into other documents. There are a
number of word processors and desktop publishing systems, which could
import vector-formatted graphics files for editing and printing.
The postprocessor supports following graphics formats:
* Computer Graphics Metafile - CGM (ISO 8632-3:1992 compliant).
* PostScriptR language by AdobeR System Incorporated. PostScript file
created by QuickField could be directly sent to any PostScript printer.
* Encapsulated PostScript - EPS. An EPS file is a standard
PostScript language file, destined to be included in other
documents as an illustration. EPS file created by QuickField also
conforms to Adobe Illustrator ( R) format, that in many cases allows
not only to print, but also to edit the graphics image.
To save the field picture to file, choose "Export" in the "File" menu.
The "Line Styles" box allows you to select appropriate line styles and
widths for separate field picture elements. The line width is measured in
points-typographic unit equal to 1/72 inch. "Hair" line means line of
minimum width allowed for the printer device. "Dot" means dotted line of
the same width. To revert line styles to default settings, choose "Reset".
Note: Appearance of imported field picture elements in some
applications depends on the features of graphics import filter used
by those applications, e.g., several filters do not support dotted
line style.
With the Color Grades text box you can change the number of colors used for
the color map. If the exporting color mode is black and white, shades of
gray are used instead of rainbow colors.
We recommend exporting in "Full Color" mode only when you are really
planning to use the color printer.
To export the X-Y plot currently drawn on the screen, choose "Export" in
the "File" menu. The corresponding dialog box is similar to the
"Export Picture" dialog box.
9.6.2 Exporting Local Values to the Table File
The local values of physical quantities obtained in the "Values" mode (see
"Access to Local Field Data") can be logged to the table file. This file
has self explaining ASCII format, with values separated with spaces or
commas. The table file can be used for printing numerical results, or to
pass them to other application program, e.g., a spreadsheet program to
produce a report.
To open the table file choose "Open Table" from the "File" menu. The dialog
box will appear, asking for the name of the table file, its format and the
set of the field quantities to be included in the table. The table also may
contain optional header. Existing files may be appended or overwritten.
Once this option is activated, for every point you click in the "Values"
mode, a line is written to the table file.
If you wish other filename, than what is suggested, you can type it in the
"File" text box, or choose "Browse" to pick the filename from the
directory.
The list of currently selected quantities is displayed in the "Columns"
list box. To add some quantity to the list:
1. Select the option button corresponding to the group, to which that
quantity belongs. The list of available quantities will be redisplayed
in accordance to the group chosen.
2. Select the needed quantity from the list box and choose "Add", or
double-click in the list. That quantity will appear in the "Columns"
list box.
To delete some quantity from the list of currently selected quantities,
select that quantity in the "Columns" list box and choose "Delete" or
double-click in the list.
Values in the table can be separated with spaces or commas (the default
extensions are .TXT and .CSV, respectively). In some cases, comma-separated
tables are better understood by the spreadsheet applications.
To close output to the table file, choose "Close Table" from the "Options"
menu.
9.6.3 Exporting Field Values along the Contour to the Table File
You can save field data in the points, distributed along the currently
selected contour, to the table file of the same format that is used for
exporting local field values, described in "Exporting Local Values to the
Table File". To save the data, choose "Tabulate" in "X-Y Plot" menu. The
dialog box appears, allowing you to manage the format and contents of the
table.
In addition to the controls in the "Open Table" dialog box, this dialog box
allows you to control the number of rows in the table. You can enter the
value in the "Rows Number" text box. Its meaning depends on option button
selection below the text box. If "At Whole Contour" is selected, the table
will contain that number of rows, equally distributed along the contour and
accounting its ends. If selected is "In Each Segment", given number of
points will be equally distributed along each segment, constituting the
contour. The total number of rows in the table will be that number
multiplied by the number of segments (plus one additional row, if the
contour is not closed).
Also, some additional quantities are available: the distance from the
contour start, and normal and tangential components of the vector and
tensor quantities, with respect to local contour direction.
9.6.4 Fast Printing the Results
If you do not need high quality printing, or if you want to get hardcopy to
the printer, that does not support PostScript language, QuickField offers
some special capabilities.
QuickField supports special mode for screen hardcopies, when the field
picture or X-Y plot is enlarged to entire screen ("Maximize" position in
the menu). There is also a color scheme suited for creating monochrome
screen hardcopies. You can select this color scheme with "Options Colors"
command, which is available in main QuickField and Postprocessor menus.
If you run QuickField under MS-DOS 5.0 or higher and the GRAPHICS program
is resident, you can obtain the screen hardcopy by pressing
SHIFT+PRINT SCREEN on the keyboard.
If you run QuickField under Windows, pressing PRINT SCREEN copies the
QuickField screen image to the clipboard, which allows you to use this
image in Windows based applications.
9.7 Additional Options
9.7.1 Saving the Postprocessor State
Current state of the Postprocessor can be saved to the special ."SST" file
and restored from it later. The current state includes: chosen method of
presentation, selected quantity, scales, ranges, current contour state,
color table, etc. If you analyze several similar problems or the results of
the same problem several times, you can save a lot of work by reusing the
same Postprocessor parameters once saved in the .SST file.
Choose "Save Setup" from the "Options" menu to save current Postprocessor
state and "Load Setup" from the same menu to restore this state from the
file. In both cases you will be inquired to supply the file name. The
default file name is constructed from the current problem name and .SST
extension.
9.7.2 Controlling Legend Display
The legend for the color map shows the correspondence between colors and
number; and for X-Y plot-between curves and quantities.
The legend appears in special window after each redrawing of the field
picture or X-Y plot until any key pressed. It can be displayed again by
choosing "Legend" from the menu.
To control the legend visibility in maximized view, choose "Show Legend"
toggle in "Options" menu.
9.7.3 Changing Color Scheme
The QuickField package has several alternative color schemes. You can
switch between these schemes from the main menu of the package as well as
form the main menu of the postprocessor. In both cases, choose "Colors"
from "Options" menu.
QuickField stores chosen scheme in QFIELD.INI file.
10. Examples
This chapter contains descriptions of the example problems supplied in the
EXAMPLES directory. Each problem in this directory is represented by the
complete data base, which includes geometric model, finite element mesh,
definition of material properties, loads and boundary conditions, and ready
analysis results. Supplied analysis results allow you to look instantly at
the postprocessing capabilities without spending time for preparing data
and solving the problem.
Some of the example descriptions included in this chapter represent an
alternative approach with detailed step-by-step description of the modeling
process, data preparation, and postprocessing of the results. They are
provided to illustrate effective modeling techniques and to give you an
opportunity to learn QuickField by following an example.
10.1 Magnetic Problems
10.1.1 MAGN1: Nonlinear Permanent Magnet
A permanent magnet and a steel keeper in the air.
Problem Type:
A nonlinear plane-parallel problem of magnetostatics.
Geometry:
+------------------------------------------------------+
!Q R !
! !
! !
! M +----------------------------------+ N !
! ! ! !
! ! ! !
! ! Iron ! !
! ! ! !
! ! ! !
! K +----------------------------------+ L !
! !
!
! G +------+H I ------- + J !
! ! ! ! ! !
! !Alnico! !Alnico ! !
! ! !D E ! ! !
! C +------+------------------ +------ + F !
! ! ! !
! ! Iron ! !
! ! ! !
! +----------------------------------+ !
! A B !
! !
!O P !
+------------------------------------------------------+
The permanent magnets are made of ALNICO, coercive force is 147218 A/m. The
polarizations of the magnets are along vertical axis opposite to each
other.
The demagnetization curve for ALNICO:
H (A/m) -147218 -119400 -99470 -79580 -53710 -19890 0
B (T) 0. 0.24 0.4 0.5 0.6 0.71 0.77
The B-H curve for the steel:
H (A/m) 400 600 800 1000 1400 2000 3000 4000 6000
B (T) 0.73 0.92 1.05 1.15 1.28 1.42 1.52 1.58 1.60
Comparison of Results
Maximum flux density in Y-direction:
ANSYS 0.42
Students' 0.40
QuickField
Professional 0.417
QuickField
See the MAGN1.PBM problem in the EXAMPLES directory.
All dimensions are in centimeters.
Step-by-step Description
Let us learn, how to solve this problem from scratch. We'll forget the
solution made in MAGN1.PBM, and start a new problem, MAGNET.PBM.
To create a new problem:
1. Choose "New" in the "Files" menu (ALT+F, N); the dialog box appears,
asking for the filename for new problem.
2. Change, if needed, the drive and directory in the "Directories" list
box.
3. Type magnet in the "Filename" box.
4. Choose "OK".
The extension .PBM will be added automatically.
To select convenient length measurement units (millimeters):
1. Choose "Length Units" in the "Options" menu. A dialog box appears.
2. Select "Millimeters".
3. Choose "OK".
To assign the problem with appropriate features:
1. Choose "Problem" in the "Edit" menu (ALT+E, P). The
"Problem Description" dialog box appears.
2. Select "Magnetostatics" in the "Problem Type" drop-down list box.
3. Select "XY Plane".
We'll agree with suggested model and data file names (MAGNET.MOD and
MAGNET.DMS.) If the "Library Data" filename box is not empty, clear it,
since we'll define all the labels in the local data file (MAGNET.DMS.)
We can start editing the model or the data directly in the
"Problem Description" dialog box. To edit the model:
1. Select the "Geometry" text box (click anywhere in the box with a mouse,
or press ALT+G, or press TAB until the selection reaches the box.)
2. Choose the "Open" button.
The Model Editor starts.
First, we should make a decision concerning dimensions of the problem's
region. Since the given problem is physically unbounded, the magnetic
system must be surrounded with a layer of air thick enough to neglect the
influence of the boundary. We suppose that three times the width of the air
gap between the magnet and the steel keeper will be a satisfactory
thickness of the air layer around the magnet, so the rectangle 100'100 mm
will fit our region's geometry.
The first step with the new model in Model Editor is to adjust window
dimensions fitting the problem's region. Since the problem has vertical
axis of symmetry, it is convenient to set zero of x-axis at the axis of
symmetry. So the region fits the square (-50 # x # 50, 0 # y # 100) To
assign these values to the window limits:
1. Choose "Keyboard" in the "Zoom" menu.
2. Type the values in appropriate text boxes.
3. Press ENTER or click the dialog box background anywhere outside options.
Now we can proceed with defining the geometry itself. To define the
vertices which correspond to points labeled with letters A through R on the
sketch:
1. Enter "Add Vertex" mode in the "Model" menu. The plus sign cursor (+)
arises in the large window indicating the point locating mode.
2. Use DIRECTION keys or a mouse to move cursor from point to point and
press ENTER or click left mouse button where you want the vertex to be
located. New vertices immediately appear in the window. Or, press TAB,
type coordinates, and press ENTER for each new vertex Create vertices
with coordinates: (-20, 20), (20, 20), (-20, 30), (-10, 30), (10, 30),
(20, 30), (-20, 40), (-10, 40), (10, 40), (20, 40), (-20, 50), (20, 50),
(-20, 70), (20, 70), (-50, 0), (50, 0), (-50, 100), and (50, 100). Don't
worry about making mistakes-you can remove erroneous vertices later.
3. Press ESC to return to the "Model" menu.
If you have created excess points, you can remove them now:
1. Choose "Delete Vertex". The X-shaped cursor appears to indicate the
picking mode. Consecutively pick excess vertices, which immediately
disappear.
2. Press ESC to return to the "Model" menu.
Now we can create edges connecting the vertices:
1. Choose "Add Edge". A dialog box appears asking the arc angle for new
edges.
2. Press ENTER (or click gray background of the dialog box) to agree with
suggested zero value, which means creating the straight lines. The
picking mode (X-shaped) cursor appears in the window.
3. Pick points A, B, F, C, A consecutively to create edges, which
constitute the rectangle ABFC. The edges immediately appear on the
screen. In fact, we created six edges, not four, because edge FC was
split into three (FE, ED and DC) while creating.
4. Press ESC to break the chain of edges and start a new one.
5. Repeat last two actions to create chains CGHD, EJGF, rectangle KLNM and
bounding rectangle OPRQ.
6. Press ESC to return to the "Model" menu.
You can remove erroneous edges, using the "Delete Edge" command.
We are done with the model's geometry. Now we can assign labels to
geometrical objects to describe material properties, sources and boundary
conditions.
The problem contains four materials having different properties: the air,
the steel and two pieces of permanent magnet, which differ in direction of
magnetization vector. To be clear, we can use the labels Air, Steel,
ALNICO Up and ALNICO Dn to label appropriate blocks. To assign these labels
to blocks:
1. Press ESC to close the "Model" menu and return to the main menu of the
Model Editor.
2. Choose "Label Blocks" in the "Label" menu. The picking mode cursor
arises.
3. Pick inside the CDHG rectangle. The block becomes highlighted and the
dialog box appears asking for the label value.
4. Type ALNICO Dn and press ENTER. The X-shaped cursor appears again.
5. Repeat the last two actions to label the CDJI rectangle as ALNICO Up,
the ABFC rectangle as Steel and the OPRQ as Air.
6. Pick inside the KLNM rectangle. Because the Steel label already exists,
you can simply pick it in the list of existing labels instead of typing
and then press ENTER. (You can also use the "Select" command to assign
some label to several blocks at once.)
7. Press ESC to return to the "Label" menu.
Edge labels are used to define specific boundary conditions on inner and
outer boundaries of the region. In our case, we need to specify zero
Dirichlet boundary condition for the outer boundary (rectangle OPRQ). To
assign labels to edges:
1. Choose "Select" and then double-click "Edges" option in the
corresponding dialog box. The picking mode cursor arises.
2. Pick consecutively four edges, which constitute the rectangle OPRQ.
Those edges become highlighted that indicates the selection. If you have
selected excess edge, pick it once more to unselect it.
3. Press ESC to cancel selection mode.
4. Choose "Label Selected". A dialog box appears asking for the label
value.
5. Type Zero and press ENTER to assign the label to selected edges.
Now we have finished with assigning labels to geometrical objects. You can
check their values in the "Find Label" mode.
We can proceed with building a mesh of finite elements. To define the mesh
density, we need to define mesh spacing parameters in several vertices of
the model. We suppose that the field is most non-homogeneous around the
magnets, so the mesh there must be maximum dense. Therefore, we'll assign
the spacing value of 1 mm to the vertices G, H, I and J and the value of
5 mm to the vertices O, P, R and Q to build the mesh of approximately 2000
nodes. To define spacing values:
1. Press ESC to return from the "Label" menu to the main menu.
2. Choose "Mesh" to open the mesh building menu.
3. Choose "Select" and then double-click "Vertices" option in the
corresponding dialog box. The picking mode cursor arises.
4. Select vertices G, H, I and J and press ESC to return to the "Mesh"
menu.
5. Choose "Set Spacing". A dialog box appears asking for the spacing value.
6. Type 1 and press ENTER. This value is now assigned to selected vertices.
7. Choose "Select" and double-click "Unselect All" option to unselect all
previously selected objects.
8. Choose "Select" and double-click "Vertices" option again.
9. Select vertices O, P, R and Q.
10.Choose "Set Spacing", type 5 and press ENTER. The model is now ready to
build the mesh.
11.Choose "Build Mesh". A dialog box appears asking, which blocks you want
to mesh.
12.Choose "In All Blocks" to build the meshes for all blocks at once.
Now the model is ready. To exit the Model Editor with saving the file:
1. Press ESC twice to close the "Mesh" menu and quit. The box appears
prompting you to save the model file.
2. Choose "Yes" to confirm saving operation.
You have returned to the "Problem Description" dialog box. Let us continue
with defining data for material properties and boundary conditions. To
start editing data file:
1. Select the "Data" text box.
2. Choose the "Open" button. A dialog box appears warning you that the file
MAGNET.DMS does not exist.
3. Choose "OK" to create new data file.
The "Properties Description File" dialog box appears. It contains labels,
which you have just defined in the model. The label names are marked with
asterisks to outline the fact, that the data for these labels are not yet
defined. Now we need to select the labels one-by-one and to define the data
for them.
To define the data for block label Air:
1. Select its name in the list box (click it with a mouse, or press ALT+B
and use DOWN key to highlight the name's field.)
2. Choose "Open" button (or press ENTER as "Open" is the default button, or
double-click on the name's field.)
A dialog box appears, prompting to enter material properties and
distributed source for block label Air. To assign values:
1. Type 1 in any text box for components of magnetic permeability tensor.
2. Choose "OK".
Now we'll learn how to describe nonlinear magnetic properties by means of
editing the B-H curve. To start editing for block label Steel:
1. Select its name in the list box and choose "Open" button. The property
editing dialog box appears.
2. Select the "Nonlinear" box. This causes starting the B-H Curve Editor.
With the Curve Editor, you can simply enter the values from the table,
point by point, checking the curve in the graph to the left of the table.
The point (0; 0) is always presented in the table, which cannot be edited
nor deleted. Since the cursor is already in the box for new B value, you
can start entering new points. To create the first point (B = 0.73 T,
H = 400 A/m, see the steel magnetisation table:
1. Type 0.73 and press ENTER. The cursor will move to the box for H value.
2. Type 400 and press ENTER. The new point will be added to the table and
immediately displayed in the graph. The cursor will return back to the
box for B value.
3. Repeat these actions for other points of the table. Points may be
entered in any order.
In case of mistyping, the erroneous point would in general produce a
noticeable anomaly in the displayed curve. You can select this point in the
graph or in the table and then delete it or correct its coordinates.
When you are done with entering points, and the curve looks like classic
B-H curve, choose the "Close" button to finish curve editing and return to
property editing dialog. Since we do not want to change any more values,
choose "OK" button to finish editing data for label Steel.
Describing data for the permanent magnet is a bit more complicated. In
addition to demagnetization curve, the direction of resistant magnetization
should be specified by means of the vector of coercive force. Now we'll
define the demagnetization curve for label ALNICO Up:
1. Select its name in the list box and choose "Open" button. The property
editing dialog box appears.
2. Type 1 in any text box for components of magnetic permeability tensor.
This is void action, the only purpose of which is to specify that the
data for the label is not empty, so that other text boxes will become
available.
3. Select the text box for y-component of coercive force and type 147218.
4. Choose the "Nonlinear" box. This starts the B-H Curve Editor.
Note that the predefined point is now at (-147218, 0). It is exactly the
first point from the B-H curve table. Now we can continue with adding all
other points from the table. When this job is done, choose the "Close"
button to finish curve editing and return to property editing dialog. Then
choose "OK" button to finish editing data for label ALNICO Up.
To define data for label ALNICO Dn, we need not repeat all this actions. We
can simply copy the data from ALNICO Up, and change the direction of the
coercive force. To do this:
1. Select ALNICO Up in the list box.
2. Choose "Copy". The dialog box appears asking for destination label name.
3. Change ALNICO Up to ALNICO Dn and choose "OK". The data for these labels
are now the same.
4. Select ALNICO Dn in the list box and choose "Open".
5. Select the text box for y-component of coercive force and insert minus
sign before digits to change the direction of coercive force to the
opposite one.
6. Choose "OK".
Now we'll continue with edge labels' data. We'll define the label Zero as
homogeneous Dirichlet boundary condition (A = 0). To define the data for
edge label Zero:
1. Select its name and choose "Open". A dialog box appears, allowing to
assign to edge label any of possible boundary conditions.
2. Select the "Dirichlet Condition" box. Zero value of pre-defined
potential will be suggested.
3. Choose "OK".
All the data needed to solve the problem is now defined. To exit from data
editing mode:
1. Choose "Close" button in the "Properties Description File" dialog box. A
dialog box appears, prompting you to save changes to data file.
2. Choose "Yes" to save changes. Now you return to the
"Problem Description" dialog box again.
3. Choose "OK".
At last, we can solve the problem and analyze the solution. To do this in
one step:
1. Choose "Analyze" from the "Results" menu. You will be suggested to solve
the problem first, as the results are absent.
2. Choose "OK".
10.1.2 MAGN2: Solenoid Actuator
A solenoid actuator consists of a coil enclosed in a ferromagnetic core
with a plunger. Calculate the magnetic field and a force applied to the
plunger.
Problem Type:
A nonlinear axisymmetric problem of magnetics.
Given:
Relative permeability of air and coil m = 1;
Current density in the coil j = 1x10 A/m ;
The B-H curve for the core and the plunger:
H (A/m) 460 640 720 890 1280 1900 3400 6000
B (T) 0.80 0.95 1.00 1.10 1.25 1.40 1.55 1.65
Problem:
Obtain the magnetic field in the solenoid and a force applied to the
plunger.
Solution:
This magnetic system is almost closed, therefore outward boundary of the
model can be put relatively close to the solenoid core. A thicker layer of
the outside air is included into the model region at the plunger side,
since the magnetic field in this area cannot be neglected.
Mesh density is chosen by default, but to improve the mesh distribution,
three additional vertices are added to the model. We put one of this
vertices at the coil inner surface next to the plunger corner, and two
others next to the corner of the core at the both sides of the plunger.
A contour for the force calculation encloses the plunger. It is put in the
middle of the air gap between the plunger and the core. While defining the
contour of integration, use a strong zoom-in mode to avoid sticking the
contour to existing edges.
The calculated force applied to the plunger F = 374.1 N.
See the MAGN2.PBM problem in the EXAMPLES directory. Load the Postprocessor
setup from the MAGN2.SST file to get the predefined contour for the force
calculation.
Comparison of Results
Maximum flux density in Z-direction in the plunger:
Bz (T)
Reference 0.933
QuickField 1.0183
Reference
D. F. Ostergaard, "Magnetics for static fields", ANSYS revision 4.3,
Tutorials, 1987.
10.1.3 MAGN3: Ferromagnetic C-Magnet
A permanent C-magnet in the air. The example demonstrates how to model
curved permanent magnet using the equivalent surface currents.
Problem Type:
Plane problem of magnetics.
Given:
Relative permeability of the air m = 1;
Relative permeability of the magnet m = 1000;
Coercive force of the magnet Hc = 10000 A/m.
The polarization of the magnet is along its curvature.
Solution:
To avoid the influence of the boundaries while modeling the unbounded
problem, we'll enclose the magnet in a rectangular region of air and
specify zero Dirichlet boundary condition on its sides.
Magnetization of straight parts of the magnet is specified in terms of
coercive force vector. Effective surface currents simulate magnetization in
the middle curved part of the magnet.
See the MAGN3.PBM problem in the EXAMPLES directory.
10.2 Time-Harmonic Magnetic Problems
10.2.1 HMAGN1: Slot Embedded Conductor
Problem Type:
A plane problem of time-harmonic magnetic field.
Geometry:
+--------------+---------+---------------+
| | | |
| | Air | |
| | | |
| +-------- + |
| Steel | | Steel |
| | | |
| +------+ +------+ |
| | | |
| | | |
| | Cooper Bar | |
| | | |
| | | |
| +-----------------------+ |
| |
+----------------------------------------+
A solid copper conductor embedded in the slot of an electric machine
carries a current I at a frequency f.
Given:
Magnetic permeability of air mu = 1;
Magnetic permeability of copper mu = 1;
Conductivity of copper sigma = 5.8005x10e7 S/m;
Current in the conductor I = 1 A;
Frequency f = 45 Hz.
Problem:
Determine current distribution within the conductor and complex impedance
of the conductor.
Solution:
We assume that the steel slot is infinitely permeable and may be replaced
with a Neumann boundary condition. We also assume that the flux is
contained within the slot, so we can put a Dirichlet boundary condition
along the top of the slot. See HMAGN1.PBM problem in the EXAMPLES directory
for the complete model.
The complex impedance per unit length of the conductor can be obtained from
the equation
Z = V / I,
where V is a voltage drop per unit length. This voltage drop can be
obtained in the Postprocessor (choose "Results", "Analyze", "Values",
"Complex", and then pick an arbitrary point within the conductor.)
Comparison of Results
Re Z (Ohm/m) Im Z (Ohm/m)
Reference 1.7555x10e-4 4.7113x10e-4
QuickField 1.7550x10e-4 4.7112x10e-4
Reference
A. Konrad, "Integrodifferential Finite Element Formulation of
Two-Dimensional Steady-State Skin Effect Problems", IEEE Trans. Magnetics,
Vol MAG-18, No. 1, January 1982.
10.2.2 HMAGN2: Symmetric Double Line of Conductors
Problem Type:
A plane problem of time-harmonic magnetic field.
Geometry:
+---------------------------------------------------+
| Coating |
| +-----------------------------------------+ |
| | | |
| | Air | |
| | +-----------+ +------------+ | |
| | | | | | | |
| | | Conductor | | Conductor | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | +-----------+ +------------+ | |
| | | |
| | | |
| +-----------------------------------------+ |
| |
+---------------------------------------------------+
Two copper square cross-section conductors with equal but opposite currents
are contained inside rectangular ferromagnetic coating. All dimensions are
in millimeters.
Given:
Magnetic permeability of air mu = 1;
Magnetic permeability of copper mu = 1;
Conductivity of copper sigma = 5.6x10e7 S/m;
Magnetic permeability of coating mu = 100;
Conductivity of copper sigma = 1.0x10e6 S/m;
Current in the conductors I = 1 A;
Frequency f = 100 Hz.
Problem:
Determine current distribution within the conductors and the coating,
complex impedance of the line, and power losses in the coating.
Solution:
We assume that the flux is contained within the coating, so we can put a
Dirichlet boundary condition on the outer surface of the coating. See
HMAGN2.PBM problem in the EXAMPLES directory for the complete model.
The complex impedance per unit length of the line can be obtained from the
equation
Z = (V1 - V2) / I,
where V1 and V2 are voltage drops per unit length in each conductor. These
voltage drops are equal with opposite signs due to the symmetry of the
model. To obtain a voltage drop choose "Results", "Analyze", "Values",
"Complex", and then pick an arbitrary point within a conductor.
The impedance of the line Z = 4.93x10e-4 + i 7.36x10e-4 Ohm/m.
To obtain power losses in the coating:
1. In the postprocessing mode choose "Integrals", "Edit Contour",
"Add Block" and pick the coating block. Press right mouse button or ESC
key twice to return to the Integral Calculator dialog box.
2. Select Joule heat from the list of integral quantities and choose
"Calculate".
The power losses in the coating P = 4.65x10-5 W/m.
10.3 Electrostatic Problems
10.3.1 ELEC1: Microstrip Transmission Line
A shielded microstrip transmission line consists of a substrate, a
microstrip, and a shield.
Problem Type:
Plane-parallel problem of electrostatics.
Geometry:
The transmission line is directed along z-axis, its cross section is shown
on the sketch. The rectangle ABCD is a section of the shield, the line EF
represents a conductor strip.
Geometry:
Shield
-------
/
/
D +----------------------------------------- + C
! !
! !
! Air Conductor !
! ----------- !
! / !
! / !
! / !
G ! E / F ! H
+---------------=========----------------- +
! !
! Substrate !
! J !
A +-------------------o--------------------- + B
Given:
Relative permittivity of air e = 1;
Relative permittivity of substrate e = 10.
Problem:
Determine the capacitance of a transmission line.
Solution:
There are several different approaches to calculate the capacitance of the
line:
* To apply some distinct potentials to the shield and the strip and to
calculate the charge that arises on the strip;
* To apply zero potential to the shield and to describe the strip as having
constant but unknown potential and carrying the charge, and then to
measure the potential that arises on the strip.
Both these approaches make use of the equation for capacitance:
C = q / U.
Other possible approaches are based on calculation of stored energy of
electric field. When the voltage is known:
C = 2 * W / (U * U),
and when the charge is known:
C = q*q / (2 * W)
Experiment with this example shows that energy-based approaches give little
bit less accuracy than approaches based on charge and voltage only. The
first approach needs to get the charge as a value of integral along some
contour, and the second one uses only a local value of potential, this
approach is the simplest and in many cases the most reliable.
The first and third approaches are illustrated in the ELEC1_1.PBM problem
in the EXAMPLES directory, and the ELEC1_2.PBM explains the second and the
fourth approaches.
Results:
Theoretical result: C = 178.1 pF/m.
Approach 1: C = 177.83 pF/m (99.8%).
Approach 2: C = 178.47 pF/m (100.2%).
Approach 3: C = 177.33 pF/m (99.6%).
Approach 4: C = 179.61 pF/m (100.8%).
Step-by-step Description
Let us learn, how to solve this problem from scratch, using the second
approach. We'll forget the solution made in ELEC1_2.PBM, and start a new
problem, STRIP.PBM.
To create the new problem:
1. Choose "New" in the "Files" menu (ALT+F, N); the dialog box appears,
asking for the filename for new problem.
2. Change, if needed, the drive and directory in the "Directories" list
box.
3. Type strip in the "Filename" box.
4. Choose "OK".
The extension .PBM will be added automatically.
To select convenient length measurement units (centimeters):
1. Choose "Length Units" in the "Options" menu. A dialog box appears.
2. Select "Centimeters".
3. Choose "OK".
To assign the problem with appropriate features:
1. Choose "Problem" in the "Edit" menu (ALT+E, P). The "Problem
Description" dialog box appears.
2. Select "Electrostatics" in the "Problem Type" drop-down list box.
3. Select "XY Plane".
We'll agree with suggested model and data file names (STRIP.MOD and
STRIP.DES.) If the "Library Data" filename box is not empty, clear it,
since we'll define all the labels in the local data file (STRIP.DES.)
We can start editing the model or the data directly in the "Problem
Description" dialog box. To edit the model:
1. Select the "Geometry" text box (click anywhere in the box with a mouse,
or press ALT+G, or press TAB until the selection reaches the box.)
2. Choose the "Open" button.
The Model Editor starts.
The first step with the new model in Model Editor is to adjust window
dimensions fitting the problem's region. Since the problem has vertical
axis of symmetry, it is convenient to set zero of x-axis at the axis of
symmetry. So the region fits the square (-5 # x # 5, 0 # y # 10.) To assign
these values to the window limits:
1. Choose "Keyboard" in the "Zoom" menu.
2. Type the values in appropriate text boxes.
3. Press ENTER or click the dialog box background anywhere outside options.
Now we can proceed with defining the geometry itself. To define the
vertices which correspond to points labeled with letters A through F in the
sketch:
1. Enter "Add Vertex" mode in the "Model" menu. The plus sign cursor (+)
arises in the large window indicating the point locating mode.
2. Use DIRECTION keys or a mouse to move cursor from point to point and
press ENTER or click left mouse button where you want the vertex to be
located. New vertices immediately appear in the window.
3. Or, press TAB, type coordinates, and press ENTER for each new vertex
Create vertices with coordinates (-5, 0), (5, 0), (5, 10), (-5, 10),
(-0.5, 1), and (0.5, 1). Don't worry about making mistakes-you can
remove erroneous vertices later.
4. Press ESC to return to the "Model" menu.
If you have created excessive points, you can remove them now:
1. Choose "Delete Vertex". The X-shaped cursor appears to indicate the
picking mode. Consecutively pick excess vertices, which immediately
disappear.
2. Press ESC to return to the "Model" menu.
Now we can create edges connecting the vertices:
1. Choose "Add Edge". A dialog box appears asking the arc angle for new
edges.
2. Press ENTER (or click gray background of the dialog box) to agree with
suggested zero value, which means creating straight lines. The picking
mode (X-shaped) cursor appears in the window.
3. Pick points A, B, C, D, A consecutively to create edges, which
constitute the rectangle ABCD. The edges immediately appear on the
screen.
4. Press ESC twice to return to the "Model" menu.
You can remove erroneous edges, using the "Delete Edge" command.
We need some additional constructing to create edges separating substrate
from the air. The easy way to create them is to copy the edge AB shifting
it 1 cm up. To make a copy:
1. Choose "Select" and then double-click "Edges" option. The picking mode
(X-shaped) cursor appears.
2. Pick the edge AB and press ESC to return to menu.
3. Choose "Copy Selected". A dialog box with the parameters for copy
operation appears.
4. Select delta-y box and type 1.
5. Choose OK, and then confirm the operation by choosing "Create".
The copy of the line segment AB crosses vertices E and F and produces three
edges separated by these vertices.
We are done with the model's geometry. Now we can assign labels to
geometrical objects to describe material properties, sources and boundary
conditions.
The model contains two blocks having different material properties: the air
and the substrate. To be clear, we can use the word Air to label the upper
block and Substrate for the lower one. To assign these labels to blocks:
1. Press ESC to close the "Model" menu and return to the main menu of the
Model Editor.
2. Choose "Label Blocks" in the "Label" menu. The picking mode cursor
arises.
3. Pick the upper block. It becomes highlighted and the dialog box appears
asking for the label value.
4. Type Air and press ENTER. The X-shaped cursor appears again.
5. Pick the lower block, type Substrate and press ENTER.
6. Press ESC to return to the "Label" menu.
Edge labels are used to define specific boundary conditions on inner and
outer boundaries of the region. In our case, we need to specify boundary
conditions for the shield (rectangle ABCD) and for the strip (line EF). To
assign labels to edges:
1. Choose "Select" and double-click "Edges" option (we'll select several
edges to assign a label to them at once.)The picking mode cursor arises.
2. Pick consecutively six edges, which constitute the rectangle ABCD. Those
edges become highlighted that indicates the selection. If you have
selected excess edge, pick it once more to unselect it.
3. Press ESC to cancel selection mode.
4. Choose "Label Selected". A dialog box appears asking for the label
value.
5. Type Shield and press ENTER to assign the label to selected edges.
6. Choose "Label Edges". The picking mode cursor appears. This mode is
convenient for assigning labels edge-by-edge.
7. Pick the edge EF. A dialog box appears.
8. Type Strip and press ENTER to assign the label.
9. Press ESC to return to the "Label" menu.
We also need to assign vertex label to any vertex contacting the strip, to
specify that the strip is charged. No matter which vertex you choose, the
charge will be distributed through all the conductor. To assign the label
to a vertex:
1. Choose "Label Vertices". The picking mode cursor arises.
2. Pick one vertex, E or F. A dialog box appears asking for the label
value.
3. Type Charge and press ENTER to assign the label to the vertex.
4. Press ESC to return to the "Label" menu.
Now we have finished with assigning labels to geometrical objects. You can
check their values in the "Find Label" mode.
We can proceed with building a mesh of finite elements. To define the mesh
density, we need to define spacing parameters in several vertices of the
model. We suppose that the electric field is most non-homogeneous near the
ends of the strip, so the mesh there must be very fine. Therefore, we'll
assign the spacing value of 0.2 cm to the vertices E and F and the value of
0.5 cm to the vertices A, B, C and D to build the mesh of approximately
1000 nodes. To define spacing values:
1. Press ESC to return from the "Label" menu to the main menu.
2. Choose "Mesh" to open the mesh building menu.
3. Choose "Select" and double-click "Vertices" option. We'll assign one
spacing value to several vertices at once.
4. Select vertices A, B, C and D and press ESC to return to the "Mesh"
menu.
5. Choose "Set Spacing". A dialog box appears asking for the spacing value.
6. Type 0.5 and press ENTER. This value is now assigned to selected
vertices.
7. Choose "Select" and double-click "Unselect All" option to unselect all
previously selected objects.
8. Choose "Select" and double-click "Vertices" option.
9. Select vertices E and F.
10.Choose "Set Spacing", type 0.2 and press ENTER. The model is now ready
to build the mesh.
11.Choose "Build All" to build the meshes for both blocks at once.
Now the model is ready. To exit the Model Editor with saving the file:
1. Press ESC twice to close the "Mesh" menu and quit. The box appears
prompting you to save the model file.
2. Choose "Yes" to confirm saving operation.
You have returned to the "Problem Description" dialog box. Let us continue
with defining data for material properties and boundary conditions. To
start editing data file:
1. Select the "Data" text box.
2. Choose the "Open" button. A dialog box appears warning you that the file
STRIP3.DES does not exist.
3. Choose "OK" to create new data file.
The "Properties Description File" dialog box appears. It contains labels,
which you have just defined in the model. The label names are marked with
asterisks to outline the fact, that the data for these labels are not yet
defined. Now we need to select the labels one-by-one and to define the data
for them.
To define the data for block label Air:
1. Select its name in the list box (click it with a mouse, or press ALT+B
and use DOWN key to highlight the name's field.)
2. Choose "Open" button (or press ENTER as "Open" is the default button, or
click a mouse once more on the name's field.)
A dialog box appears, prompting to enter material properties and
distributed source for block label Air. To assign values:
1. Type 1 in any text box for components of electric permittivity tensor.
2. Choose "OK".
Repeat last actions for the label Substrate. The value of relative
permittivity of substrate is 10.
Now we'll continue with edge labels' data. We'll define the label Shield as
a homogeneous Dirichlet boundary condition (U = 0) and the label Strip as a
conductor condition (U = const).
To define the data for edge label Shield:
1. Select its name and choose "Open". A dialog box appears, allowing to
assign to edge label any of possible boundary conditions.
2. Select the "Dirichlet Condition" box. Zero value of pre-defined
potential will be suggested.
3. Choose "OK".
To define the data for edge label Strip:
1. Select its name and choose "Open".
2. Select the "Conductor" box.
3. Choose "OK".
We need to define the vertex label Charge to assign the charge to the
strip. To determine the capacitance, the exact value of the charge does not
matter. We'll choose a value of 1.
To define the data for vertex label Charge:
1. Select its name and choose "Open". A dialog box appears, allowing to
specify the charge, or to assign the Dirichlet boundary condition.
2. Select the "Electric Charge" box.
3. Type 1 in the text box for charge value.
4. Choose "OK".
All the data needed to solve the problem is now defined. To exit from data
editing mode:
1. Choose "Close" button in the "Properties Description File" dialog box. A
dialog box appears, prompting you to save changes to data file.
2. Choose "Yes" to save changes. Now you return to the "Problem
Description" dialog box again.
3. Choose "OK".
At last, we can solve the problem and analyze the solution. To do this in
one step:
1. Choose "Analyze" from the "Results" menu. You will be suggested to solve
the problem first, as the results are absent.
2. Choose "OK" to start the solver.
After finishing, the Postprocessor starts automatically. There are many
possibilities to analyze the field in the Postprocessor. We will show only
those steps needed to determine the capacitance:
1. Choose "Values" from the menu. Cross-shaped cursor appears allowing you
to pick points to determine the local field data.
2. Move the cursor to the point (0.0, 1.0) (exactly; the convenient way is
to use the DIRECTION keys, or to press TAB and type coordinates from
keyboard.)
3. Press ENTER.
The box appears, showing you the local field data. The potential of the
strip is 5.251e+9 Volts. The capacitance is
C = q / U = 1 / 5.251e+9 = 190.4 pF/m
Note that, with plane-parallel problems, we specify the sources as specific
values per unit depth (e.g., the charge of the strip), and the result is
specific capacitance per unit depth, measured in F/m.
Since the mesh is rather rough, the solution gives less accuracy than
provided in ELEC1_2.PBM.
If you now look through the model provided with ELEC1_2.PBM, ELEC1.MOD, you
will find some hints for obtaining a very fine mesh near the vertices E and
F-the points of singularity.
Since the Model Editor cannot squeeze the mesh spacing inside the edge, but
only from one end to another, two extra vertices have been added in central
points of edges AB and EF. The first of these vertices allows the Model
Editor to adjust automatically the spacing around it, since the strip is
very close to this point. The second vertex is aimed to specify manual
spacing value for it, which helps to decrease the total number of nodes in
the mesh, without loss of precision.
10.3.2 ELEC2: Two Conductor Transmission Line
Problem Type:
A plane problem of electrostatics.
Geometry:
The problem's region is bounded by ground from the bottom side and extended
to infinity on other three sides.
Given:
Relative permittivity of air e = 1;
Relative permittivity of dielectric e = 2.
Problem:
Determine self and mutual capacitance of conductors.
Solution:
To avoid the influence of outer boundaries, we'll define the region as a
rectangle large enough to neglect side effects. To calculate the
capacitance matrix we set the voltage U = 1 V on one conductor and U = 0 on
the another one.
Self capacitance: C11 = C22 = q1 / U1;
Mutual capacitance: C12 = C21 = q2 / U1;
where charge Q1 and Q2 are evaluated on rectangular contours around
conductor 1 and 2 away from their edges. We chose the contours for the C11
and C12 calculation to be rectangles -6 < x < 0, 0 < y < 4 and 0 < x < 6,
0 < y < 4 respectively.
Comparison of Results
C11 (F/m) C12 (F/m)
Reference 9.23x10-11 -8.50x10-12
QuickField 9.43 10-11 -8.57x10-12
Reference
A. Khebir, A. B. Kouki, and R. Mittra, "An Absorbing Boundary Condition for
Quasi-TEM Analysis of Microwave Transmission Lines via the Finite Element
Method", Journal of Electromagnetic Waves and Applications, 1990.
See the ELEC2.PBM problem in the EXAMPLES directory.
10.4 Heat Transfer Problems
10.4.1 HEAT1: Slot of an Electric Machine
Temperature field in the stator tooth zone of power synchronous electric
machine.
Problem Type:
The plane-parallel problem of heat transfer with convection.
Geometry:
Stator outer diameter is 690 mm. Domain is a 10 degree segment of stator
transverse section. Two armature bars laying in the slot release ohmic
loss. Cooling is provided by convection to the axial cooling duct and both
surfaces of the core.
Given:
Specific copper loss: 360000 W/m ;
Heat conductivity of steel: 25 J/Kxm;
Heat conductivity of copper: 380 J/Kxm;
Heat conductivity of insulation: 0.15 J/Kxm;
Heat conductivity of wedge: 0.25 J/Kxm;
Inner stator surface:
Convection coefficient: 250 W/Kxm ;
Temperature of contacting air: 40.C.
Outer stator surface:
Convection coefficient: 70 W/Kxm ;
Temperature of contacting air: 20.C.
Cooling duct:
Convection coefficient: 150 W/Kxm ;
Temperature of contacting air: 40.C.
See the HEAT1.PBM problem in the EXAMPLES directory.
10.4.2 HEAT2: Cylinder with Temperature Dependent Conductivity
A very long cylinder (infinite length) is maintained at temperature Ti
along its internal surface and To along its external surface. The thermal
conductivity of the cylinder is known to vary with temperature according to
the linear function l(T) = C0 + C1xT.
Problem Type:
An axisymmetric problem of nonlinear heat transfer.
Geometry:
To Ti
---- -----
\ \
\ \
+--------------------------\--------- +
!////////////////////////// \ /////// !
+------------------------------------ +
! !
+-.--.--.--.--.--.--.--.--.--.--.--.- +
! !
+------------------------------------ +
!//////////////////////////////////// !
+------------------------------------ +
Given:
Ri = 5 mm, Ro = 10 mm;
Ti = 100.C, To = 0.C;
C0 = 50 W/Kxm, C1 = 0.5 W/Kxm.
Problem:
Determine the temperature distribution in the cylinder.
Solution:
The axial length of the model is arbitrarily chosen to be 5 mm.
Comparison of Results
Radius Quickfield Theory
0.6 79.2 79.2
0.7 59.5 59.6
0.8 40.2 40.2
0.9 20.66 20.8
See the HEAT2.PBM problem in the EXAMPLES directory.
10.5 Stress Analysis Problems
10.5.1 STRES1: Perforated Plate
A thin rectangular sheet with a central hole subject to tensile loading.
Problem Type:
Plane problem of stress analysis (plane stress formulation).
Geometry of the plate:
Length: 240 mm;
Width: 180 mm;
Radius of central opening: 30 mm;
Thickness: 5 mm.
Given:
Young's modulus E = 207000 N/mm ;
Poisson's ratio n = 0.3.
The uniform tensile loading (40 N/mm ) is applied to the bottom edge of the
structure.
Problem:
Determine the concentration factor due to presence of the central opening.
Solution:
Due to mirror symmetry one quarter of the structure is presented, and
internal boundaries are restrained in X and Y directions respectively.
The concentration factor may be obtained from the loading stress (40 N/mm2)
and the maximum computed stress (146 N/mm2) as
k = 140.8 / 40 = 3.52.
See the STRES1.PBM problem in the EXAMPLES directory.
10.6 Coupled Problems
10.6.1 COUPL1: Stress Distribution in a Long Solenoid
A very long, thick solenoid has an uniform distribution of circumferential
current. The magnetic flux density and stress distribution in the solenoid
has to be calculated.
Problem Type:
An axisymmetric problem of magneto-structural coupling.
Geometry:
+------------------------------------ +
!///////// Conducting cylinder ////// !
+------------------------------------ +
! Air !
+-.--.--.--.--.--.--.--.--.--.--.--.- +
! !
+------------------------------------ +
!//////////////////////////////////// !
+------------------------------------ +
Given:
Dimensions Ri = 1 cm, Ro = 2 cm;
Relative permeability of air and coil mu = 1;
Current density j = 1x10+5 A/m2;
Young's modulus E = 1.075x10+11 N/m2;
Poisson's ratio nu = 0.33.
Problem:
Calculate the magnetic flux density and stress distribution.
Solution:
Since none of physical quantities varies along z-axis, a thin slice of the
solenoid could be modeled. The axial length of the model is arbitrarily
chosen to be 0.2 cm. Radial component of the flux density is set equal to
zero at the outward surface of the solenoid. Axial displacement is set
equal to zero at the side edges of the model to reflect the infinite length
of the solenoid.
Comparison of Results
Magnetic flux density and circumferential stress at r = 1.3 cm:
Bz (T) Stheta (N/m2)
Reference 8.796x10-3 97.407
QuickField 8.798x10-3 96.301
Reference
F. A. Moon, "Magneto-Solid Mechanics", John Wiley & Sons, N.Y., 1984,
Chapter 4.
See the COUPL1MS.PBM and COUPL1SA.PBM problems in the EXAMPLES directory
for magnetic and structural parts of this problem respectively.
Step-by-step Description
Let us learn how to solve this problem from scratch. We'll ignore the
solution made in COUPL1MS.PBM and COUPL1SA.PBM, and start a new problem,
SOLMAG.PBM. We use a suffix "MAG" to underline that this will represent the
magnetic part of our problem.
To create new problem:
1. Choose "New" in the "Files" menu (ALT+F, N); the dialog box appears,
asking for the filename for the new problem.
2. Change, if needed, the drive and directory in the "Directories" list
box.
3. Type solmag in the "Filename" box.
4. Choose "OK".
The extension .PBM will be added automatically.
To select convenient length measurement units (centimeters):
1. Choose "Length Units" in the "Options" menu. A dialog box appears.
2. Select "Centimeters".
3. Choose "OK".
To assign the problem with appropriate features:
1. Choose "Problem" in the "Edit" menu (ALT+E, P). The "Problem
Description" dialog box appears.
2. Select "Magnetostatics" in the "Problem Type" drop-down list box.
3. Select "RZ Plane", since our problem is axisymmetric.
We'll agree with suggested data file name (SOLMAG.DMS), but change model
file name to SOL.MOD to stress out the fact, that the model file will be
shared between magnetic and stress analysis problems. If the "Library Data"
filename box is not empty, clear it, since we'll define all the labels in
the local data file (SOLMAG.DMS.)
We can start editing the model or the data directly from the "Problem
Description" dialog box. To edit the model:
1. select the "Geometry" text box (click anywhere in the box with a mouse,
or press ALT+G, or press TAB until the selection reaches the box.)
2. choose the "Open" button.
The Model Editor starts.
The first step with the new model in Model Editor is to adjust window
dimensions fitting the problem's region. Since none of the physical
quantities varies along z-axis, we'll model a thin slice of the solenoid.
We'll choose the axial length of this slice to be 0.2 cm, from -0.1 to 0.1
along z-axis. The whole model fits in the square (-1 # z # 1, -0 # r # 2.)
To assign these values to the window limits:
1. Choose "Keyboard" in the "Zoom" menu.
2. Type the values (-1, 1, 0, 2) in appropriate text boxes.
3. Press ENTER or click the dialog box background anywhere outside options.
Now we can proceed with defining the geometry itself. As the first step we
create vertices, which represent specific points of the model geometry.
We'll need six vertices with coordinates:
z -0.1 -0.1 -0.1 0.1 0.1 0.1
r 0 1 2 0 1 2
To define the vertices:
1. Enter "Add Vertex" mode in the "Model" menu. The plus sign cursor (+)
arises in the large window indicating the point locating mode.
2. Use DIRECTION keys to move cursor from point to point and press ENTER
where you want the vertex to be located. New vertices immediately appear
in the window.
3. Or, press TAB, type coordinates, and press ENTER for each new vertex.
Don't worry about making mistakessyou can remove erroneous vertices
later.
4. Press ESC to return to the "Model" menu.
If you have created excess points, you can remove them now:
1. Choose "Delete Vertex". The X-shaped cursor appears to indicate the
picking mode. Consecutively pick excess vertices, which immediately
disappear.
2. Press ESC to return to the "Model" menu.
Now we can create edges connecting the vertices:
1. Choose "Add Edge". A dialog box appears asking the arc angle for new
edges.
2. Press ENTER (or click gray background of the dialog box) to agree with
suggested zero value, which means creating the straight lines. The
picking mode (X-shaped) cursor appears in the window.
3. Pick vertices consecutively to create two rectangles one on the top of
another. Press ESC to break the chain of edges and start a new one.
4. Press ESC to return to the "Model" menu.
You can remove erroneous edges, using the "Delete Edge" command.
We are done with the model's geometry. Now we can assign labels to
geometrical objects to describe material properties, sources and boundary
conditions.
The bottom rectangle represents the air inside the solenoid, so we'll
assign the label air to it. The top rectangle represents the slice of the
solenoid coil itself, so we'll label it coil. To assign these labels to
blocks:
1. Press ESC to close the "Model" menu and return to the main menu of the
Model Editor.
2. Choose "Label Blocks" in the "Label" menu. The picking mode cursor
arises.
3. Pick inside the bottom rectangle. The block becomes highlighted and the
dialog box appears asking for the label value.
4. Type air and press ENTER. The X-shaped cursor appears again.
5. Pick inside the top rectangle. The block becomes highlighted and the
dialog box appears asking for the label value.
6. Type coil and press ENTER.
7. Press ESC to return to the "Label" menu.
Edge labels are used to define the boundary conditions. For magnetic
problem we need to specify only a zero flux condition at outward surface of
the solenoid, but to make the model suitable for the stress analysis too,
we'll also assign labels to the side edges of the coil. To assign labels to
edges:
1. Choose "Label Edges". The picking mode cursor arises.
2. Pick the top edge. The edge becomes highlighted and the dialog box
appears asking for the label value.
3. Type outer and press ENTER. The X-shaped cursor appears again.
4. Pick one of the side edges of the top rectangle and type no axial displ.
5. Pick another side edge of the coil and type no axial displ, or double
click the corresponding line in the "Existing Labels" list box.
6. Press ESC to return to the "Label" menu.
Now we have finished with assigning labels to geometrical objects. You can
check their values in the "Find Label" mode.
We can proceed with building a mesh of finite elements. For simplicity we
will use a homogeneous mesh with element size approximately equal to
0.025 cm. To build the mesh:
1. Press ESC to return from the "Label" menu to the main menu.
2. Choose "Mesh" to open the mesh building menu.
3. Choose "Set Spacing". The X-shaped pick-mode cursor appears on a screen.
4. Pick any vertex, a dialog box appears asking for the spacing value.
5. Type 0.025 and press ENTER. This value is now assigned to the vertex and
will control the mesh density in the whole region.
6. Choose "Build Mesh". A dialog box appears asking, which blocks you want
to mesh.
7. Choose "In All Blocks" "to build the meshes for all blocks at once.
Now the model is ready. To exit the Model Editor with saving the file:
1. Press ESC twice to close the "Mesh" menu and quit. The box appears
prompting you to save the model file.
2. Choose "Yes" to confirm the saving operation.
You have returned to the "Problem Description" dialog box. Let us continue
with defining data for material properties and boundary conditions. To
start editing the data file:
1. Select the "Data" text box.
2. Choose the "Open" button. A dialog box appears warning you that the file
SOLMAG.DMS does not exist.
3. Choose "OK" to create new data file.
The "Properties Description File" dialog box appears. It contains labels,
which you have just defined in the model. The label names are marked with
asterisks to outline the fact, that the data for these labels are not yet
defined. Now we need to select the labels one-by-one and to define the data
for them.
To define the data for block label air:
1. Select its name in the list box (click it with a mouse, or press ALT+B
and use DOWN key to highlight the name's field.)
2. Choose "Open" button (or press ENTER as "Open" is the default button, or
double-click on the name's field.)
A dialog box appears, prompting to enter material properties and
distributed source for block label air. To assign values:
1. Type 1 in any one of two text boxes for components of magnetic
permeability tensor.
2. Choose "OK".
To define the data for block label coil:
1. Select its name in the list box (click it with a mouse, or press ALT+B
and use DOWN key to highlight the name's field.)
2. Choose "Open" button (or press ENTER as "Open" is the default button, or
double-click on the name's field.)
A dialog box appears, prompting to enter material properties and
distributed source for block label coil. To assign values:
1. Type 1 in any one of two text boxes for components of magnetic
permeability tensor.
2. Type 1e6 in the "Current Density" text box.
3. Choose "OK".
Now we'll continue with edge labels' data. We'll specify a zero flux
condition (Bn = 0) for the outer label. To define the data for the edge
label outer:
1. Select its name and choose "Open". A dialog box appears, allowing to
assign to edge label any of possible boundary conditions.
2. Select the "Zero Flux Condition" box.
3. Choose "OK".
To define a natural boundary condition for the edge label no axial displ:
1. Select its name and choose "Open".
2. Choose "OK", the dialog box by default represents the natural boundary
condition.
All the data needed to solve the magnetic problem are now defined. To exit
from data editing mode:
1. Choose "Close" button in the "Properties Description File" dialog box. A
dialog box appears, prompting you to save changes to data file.
2. Choose "Yes" to save changes. Now you return to the "Problem
Description" dialog box again.
3. Choose "OK".
At last, we can solve the problem and analyze the magnetic field. To do
this in one step:
1. Choose "Analyze" from the "Results" menu. You will be suggested to solve
the problem first, as the results are absent.
2. Choose "OK".
3. Choose "Values" to get the field values in a particular point. The plus
sign cursor (+) arises in the large window indicating the point locating
mode.
4. Use DIRECTION keys to move cursor from point to point and press ENTER
where you want to see the field values. Or, press TAB, type coordinates,
and press ENTER for each new point.
5. Press ESC to exit the "Values" mode and another ESC to return to the
main QuickField menu.
Once we got the results for the magnetic part of our problem, we can
proceed with the stress analysis. To perform the stress analysis we will
need a new problem description.
To create new problem description:
1. Choose "New" in the "Files" menu (ALT+F, N); the dialog box appears,
asking for the filename for the new problem.
2. Type solstr in the "Filename" box.
3. Choose "OK".
The extension .PBM will be added automatically.
To assign the problem with the appropriate features:
1. Choose "Problem" in the "Edit" menu (ALT+E, P). The
"Problem Description" dialog box appears.
2. Select "Stress Analysis" in the "Problem Type" drop-down list box.
We'll agree with suggested data file name (SOLSTR.DMS), but change the
model file name to the existing SOL.MOD.
To specify the problem coupling:
1. Choose Imported Data button in the Problem Description dialog box. The
Data Imported from Other Problems dialog box appears.
2. Choose "Magnetic forces" option in "Data Type" drop-down list box.
3. Choose "Browse" button, and double-click a SOLMAG.PBM file.
4. Choose "Add" button, a new line will appear in "Data Sources" list box.
5. Choose "Close" button to return to the "Problem Description" dialog box.
Next our step is to define material properties and boundary conditions for
the structural problem. To start editing the data file:
1. Select the "Data" text box.
2. Choose the "Open" button. A dialog box appears warning you that the file
SOLSTR.DMS does not exist.
3. Choose "OK" to create new data file.
The "Properties Description File" dialog box appears. It contains labels,
which you assigned to the model. The label names are marked with asterisks
to outline the fact, that the data for these labels are not yet defined.
Now we need to select the labels one-by-one and to define the data for
them.
To define data for the block label air:
1. Select its name in the list box (click it with a mouse, or press ALT+B
and use DOWN key to highlight the name's field.)
2. Choose "Open" button (or press ENTER as "Open" is the default button, or
double-click on the name's field.)
A dialog box appears, prompting to enter material properties and
distributed source for block label air. The block labeled air has to be
excluded from stress calculation. Since the text boxes for the Young's
moduli already contain word None, the all we need to do is to choose "OK"
button.
To define data for the block label coil:
1. Select its name in the list box (click it with a mouse, or press ALT+B
and use DOWN key to highlight the name's field.)
2. Choose "Open" button (or press ENTER as "Open" is the default button, or
double-click on the name's field.)
A dialog box appears, prompting to enter material properties for block
label coil. To assign values:
1. Type 1.075e11 in any one of three text boxes for Young's moduli.
2. Type 0.33 in any one of three text boxes for Poisson's ratios.
3. Choose "OK".
Now we'll continue with edge labels' data. To define the data for the edge
label no axial displ:
1. Select its name and choose "Open". A dialog box appears, allowing to
assign to edge label any of possible boundary conditions.
2. Check the "Z" check box inside "Fixed Displacement" rectangle. The
displacement is zero by default.
3. Choose "OK".
To define the natural boundary condition for the edge label outer:
1. Select its name and choose "Open".
2. Choose "OK", the dialog box by default represents the natural boundary
condition.
All the data needed to solve the structural problem are now defined. To
exit from data editing mode:
1. Choose "Close" button in the "Properties Description File" dialog box. A
dialog box appears, prompting you to save changes to data file.
2. Choose "Yes" to save changes. Now you return to the "Problem
Description" dialog box again.
3. Choose "OK".
Now we can solve the problem and analyze stresses in the coil. To do this
in one step:
1. Choose "Analyze" from the "Results" menu. You will be suggested to solve
the problem first, as the results are absent.
2. Choose "OK".
3. Choose "Values" to get the field values in a particular point. The plus
sign cursor (+) arises in the large window indicating the point locating
mode.
4. Use DIRECTION keys to move cursor from point to point and press ENTER
where you want to see the stress value.
5. Or, press TAB, type coordinates, and press ENTER for each new point.
6. Press ESC to exit the "Values" mode and another ESC to return to the
main QuickField menu.
10.6.2 COUPL2: Cylinder Subject to Temperature and Pressure
A very long, thick-walled cylinder is subjected to an internal pressure and
a steady state temperature distribution with Ti and To temperatures at
inner and outer surfaces respectively. Calculate the stress distribution in
the cylinder.
Problem Type:
An axisymmetric problem of thermal-structural coupling.
Geometry:
To Ti
---- -----
\ \
\ \
+--------------------------\--------- +
!////////////////////////// \ /////// !
+------------------------------------ +
! !
+-.--.--.--.--.--.--.--.--.--.--.--.- +
! !
+------------------------------------ +
!//////////////////////////////////// !
+------------------------------------ +
Given:
Dimensions Ri = 1 cm, Ro = 2 cm;
Inner surface temperature Ti = 100.C;
Outer surface temperature To = 0.C;
Coefficient of thermal expansion alpha = 1x10-6 1/K;
Internal pressure P = 1x10+6 N/m2;
Young's modulus E = 3x10+11 N/m2;
Poisson's ratio nu = 0.3.
Problem:
Calculate the stress distribution.
Solution:
Since none of physical quantities varies along z-axis, a thin slice of the
cylinder can be modeled. The axial length of the model is arbitrarily
chosen to be 0.2 cm. Axial displacement is set equal to zero at the side
edges of the model to reflect the infinite length of the cylinder.
Comparison of Results
Radial and circumferential stress at r = 1.2875 cm:
Sr (N/m2) Stheta (N/m2)
Theory -3.9834x10+6 -5.9247x10+6
Students' -3.827x10+6 -5.882x10+6
QuickField
Professional -3.959x10+6 -5.924x10+6
QuickField
Reference
S. P. Timoshenko and Goodier, "Theory of Elasticity", McGraw-Hill Book Co.,
N.Y., 1961, pp. 448-449.
See the COUPL2HT.PBM and COUPL2SA.PBM problems in the EXAMPLES directory
for the corresponding heat transfer and structural parts of this problem.
10.6.3 COUPL3: Temperature Distribution in an Electric Wire
Calculate the temperature distribution in a long current carrying wire.
Problem Type:
An axisymmetric problem of electro-thermal coupling.
Geometry:
+------------------------------------ +
+//////////////////////////////////// +
+////////------> Current //////////// +
+//////////////////////////////////// +
+------------------------------------ +
Given:
Wire diameter d = 10 mm;
Resistance R = 3x10-4 Ohm/m;
Electric current I = 1000 A;
Thermal conductivity lambda = 20 W/Kxm;
Convection coefficient alpha = 800 W/Kxm2;
Ambient temperature To = 20.C.
Problem:
Calculate the temperature distribution in the wire.
Solution:
We arbitrary chose a 10 mm piece of wire to be represented by the model.
For data input we need the wire radius r = 5 mm, and the resistivity of
material:
rho = (PI * d*d * R) / 4 = 2.356e-8 Ohm*m,
and voltage drop for our 10 mm piece of the wire:
DU = I*R*l = 3e-3 (V).
For the current flow problem we specify two different voltages at two
sections of the wire, and a zero current condition at its surface. For heat
transfer problem we specify zero flux conditions at the sections of the
wire and a convection boundary condition at its surface.
Comparison of Results
Center line temperature:
T
(centigrade)
Theory 33.13
QuickField 32.83
Reference
W. Rohsenow and H. Y. Choi, "Heat, Mass, and Momentum Transfer", Prentice-
Hall, N.J., 1963.
See the COUPL3CF.PBM and COUPL3HT.PBM problems in the EXAMPLES directory
for the corresponding current flow and heat transfer parts of this problem.
Center line temperature:
T
(centigrade)
Theory 33.13
QuickField 32.83
