1. Course Outline Program Layout Program Setup Viewing Geometry Modeling
Physical Aspects
Problem Discretization
Analysis
Output

2. Program Layout Important Features Workspace: Model is displayed
Message Area: Program tells user what it wants
User Input Area: User gives program data.

3. Program Setup
Units Setup
View Setup

4. Units Setup
Unit Systems
Individual settings
User Units

5. View Setup Limits define maximum extents of the model
Rotation Step defines how finely view rotation is applied
Grid and Snap used in 2D modeling mode

6. Viewing Zooming Panning Rotating Standard Views Rendering Modes
Visibility

7. Zooming
Zoom-In and Zoom-Out – Allow you to zoom in and out on different features
Previous - To go back to the previous view
Scale view to limits – takes to to default view

8. Panning Using the Scroll bars is easiest
Pan command allows you to pan the view within the Workspace

9. Rotating View Position
Change Look-at Point
Select the rotate view icon or use the keyboard arrow keys while in a selection loop
Change the “Look-at Point” to rotate about a local feature
Use the Rotate Step setting on the View Setup to allow finer/slower or coarser/faster rotation

10. Standard Views Use standard views to quickly view from top or sides.
Standard View buttons
Use standard views to quickly view from top or sides.
Use isometric view to get back to the default 3D view position

11. Rendering Modes Change rendering modes to establish perspective.
Rendering Mode buttons
Change rendering modes to establish perspective.
Use Coarse shading density except to generate images for presentations.

12. Rendering Modes Wire-frame Rendering Solid Model Rendering
Translucent Rendering
Hidden Line Removal

13. Visibility
Visibility buttons
Use visibility to reduce the amount of visual data your brain needs to process.
HINT: Create GROUPs of geometry to more quickly and flexibly show and hide items related to the same parts of the model.

14. Geometry Modeling Fundamentals Segments Selection
Definition - Surfaces, Volumes, Groups
Extrusion
Importing Geometry – DXF, IGES, IES2D
Modification

15. Geometry Fundamentals
Basic building block is a segment
Closed, simply-connected groups of segments form surfaces
Closed groups of surfaces form volumes

16. Geometry Primitive Segments
Segment creation buttons
Segments can be lines, arcs, or splines.
Real geometry is modeled, not piecewise linear approximation.

17. Useful Keyboard Shortcuts
Algebraic expressions (e.g. X+A Y-B Z/C) Useful when entering geometry points for primitives or when extruding linear
Increment values using function keys F5-F10 Useful for defining the axis for rotation or circular sweeps.

18. Geometry Primitive Volumes
Volume primitive buttons
Cubes, Cylinders, Spheres can be constructed with separate commands
Surface and volume definitions are created in addition to the segments
Can also use these as a starting point for other volumes.

19. Geometry - Selection Change selection to desired type.
Selection Type
Change selection to desired type.
Entity that mouse is over is highlighted in orange.
Click to select highlighted entity.
If desired entity is obscured use <Ctrl> + Click to toggle between alternatives, then click when desired entity is green.
HINT: Use Solid Rendering Mode while selecting surfaces and volumes to confirm selections.

20. Surfaces, Volumes and Groups
Surfaces required for placement of surface types of physical attributes (boundary conditions) and as the basic unit of a volume.
Volumes required for placement of surface types of physical attributes (materials, volume currents, permanent magnets)
Groups are useful for selection of combinations of volumes that make up a part or which have some functional similarity.

21. Surface Definition
Surfaces must be made of three or four sides.

22. Surface Definition
Surfaces can be made of more than 4 segments by grouping multiple segments into one side.
Note the distinction between “segment” and “side”.
These four segments comprise one side

23. Surface Definition
Segments grouped into sides should meet such that their tangents are “nearly continuous” at the connection point.
Rule of thumb – interior angle greater than 135o but not greater than 225.
Bottom side is OK
Bottom side is NOT OK
Solution: Create two surfaces

24. Surface Definition
Two sides should not meet with an interior angle of 180o or greater (for four-sided surfaces).
Bad four-sided surfaces
Surface is OK, group bottom two segments into one side
Solution: Create two three-sided surfaces

25. Surface Definition
Surfaces with severe aspect ratios (i.e. one segment much shorter than the rest) should be avoided.
Rule of thumb – Opposite sides should have length ratios > 1/20
Bad aspect ratio
Solution 1: Break down into smaller surfaces with better aspect ratios
Solution 2: Remove small feature and turn into three-sided surface

26. Volume Definition Volume constructed from a closed set of surfaces
Volumes can be made up of any number of surfaces, to place volume currents, face oriented magnets, or sub-volumes, must have 6 surfaces.

27. Group Definition
Groups can be made up of segments, surfaces and volumes.
Use groups to make selection and visibility of structures of the same part easier.

28. Geometry – Extrusion
Geometry extrusion buttons
Sweep path setting
Use extrusion or “sweeps” to generate surfaces from segments and volumes from surfaces.
Use Linear sweep setting to give thickness to surfaces.
Use Circular sweep setting to create surfaces or revolution.
Use Path sweep setting to generate arbitrary shapes.

29. Geometry - Imports IGES and DXF
Best to start with 2D drawing and extrude into third dimension

30. Geometry - Modification
Displace
Rotate
Pull
Undo (one level)
Delete/Delete All
Mirror
Scale
Geometry Operation:
Copy Off Copy On Stretch
Repeat On/Off

31. Geometry - Modification
Displace – shift geometry by some vector distance
Rotate – shift geometry around a user defined axis by some angle
Mirror – Reflect geometry across user defined plane
HINT: Use Copy On setting with Repeat button set to create multiple copies.

32. Geometry - Reshaping
Pull – used to change the position of individual points

33. Geometry - Reshaping
Stretch setting – used to maintain connections while shifting geometry
Result of displacing top surface with Stretch setting

34. Geometry - Reshaping
Stretch setting – can also be used to maintain connections while scaling
Result of scaling top surface with Stretch setting

35. Geometry Construction Tools
Finding tangent lines.
Tangent to two arcs
Tangent to an arc from a point
Tangent to an arc at a point along the arc

36. Geometry Construction Tools
Rounding corner where two lines meet.
Rounding two lines of length 1 unit with radius 0.1 unit

37. Geometry Construction Tools
Finding curves of intersection of surfaces.
Want to find union of two volumes
First find curves of intersection using Intersection of Volumes command

38. Geometry Construction Tools
Break and reconnect surfaces
Reconstruct as one volume or three separate volumes

39. Physical Aspects Material Properties BH curves Electrostatics
Boundary Conditions
Volume and Surface Charges
Magnetics
Volume and Surface Currents
Permanent Magnets

40. Material Properties
Material properties include permittivity, conductivity and permeability.
Permeability can be linear (single number) or nonlinear (BH curve) data.
Change material properties in Material Table.

41. BH Curves
Edited using the Autograph utility. Note the curve fitting, slope at the end is 1.0 (saturation) Right click on curve data to edit.

42. Volume and Surface Currents
Volume currents are the most common.
If a physical coil has an extreme height:width ratio, approximate the coil by a surface current. Rule of thumb: h/w > 20 use surface current.
Aspect ratios OK for volume
h/w > 20 convert volume to surface

43. Volume and Surface Currents
Currents are applied by assigning the nI value to the appropriate geometry.
Must also select the surface where current enters the volume.
Current enters volume through this surface

44. Permanent Magnets
First must generate a second quadrant BH curve (demagnetizing curve)

45. Permanent Magnets
Direction is determined by assigning: Unit vector for magnetization direction or Magnetization normal to a geometry surface

46. Problem Discretization
BEM Fundamentals
Symmetry and Periodicity
Placement of Elements and Subvolumes

47. BEM Fundamentals
Consider the electric field from a point charge and the magnetic field from a filamentary current.
Current “out of page”
Magnetic field lines
Positive charge
Electric field lines

48. BEM Fundamentals
Placing several charges, both positive and negative, around a boundary will give a field pattern somewhat as follows: + - + -

49. BEM Fundamentals
Similarly, placing several filamentary currents around a boundary will result in a field pattern as below: + -
+ +

50. BEM Fundamentals
Equivalence principle: Material interfaces can be replaced by certain equivalent sources that will sustain the same fields. The sources are computed to satisfy fundamental boundary conditions:
n X (H1-H2)=Js n . (B1-B2)=0
n X (E1-E2)=0 n . (D1-D2)=qs
Boundary elements are placed to geometrically represent where equivalent sources are placed.

51. BEM Fundamentals i  i i e  e  e Volume Sources
Equivalent Surface Sources

52. BEM Fundamentals Boundary Elements needed on surfaces where:
Electro-statics: Permittivity Mode
Permittivity changes
Voltage, dV/dn, or Floating boundary condition is assigned
Conductivity Mode
Conductivity changes
Voltage or Current boundary condition is assigned
Permitivitty and Conductivity (Both) Mode
Any of the above

53. BEM Fundamentals Boundary Elements needed on surfaces where:
Magnetostatics:
Permeability changes
Surface current is assigned
Direction of magnetization of permanent magnets change.
Time Harmonic Magnetics:
Permeability Changes
Conductivity Changes
Permittivity Changes (when displacement currents are considered)
Surface Currents are defined

54. BEM Solution Boundary elements solved for at the nodes
Linear basis function used between nodes as shown in the 2D example below. 
Example representing the approximation of a quadratic function by a set of piece-wise linear functions

55. Element Density
There are two significant considerations with respect to the density of elements that should be used:
Resolution in the Solution
Where do the fields change most rapidly in the model?
Change in material properties over a surface (for nonlinear models)
What is being calculated

56. Subvolumes
Volumetric effects such as volume currents and the effect of inhomogeneity due to non-linear materials require the placement of sub-volumes.
Sub-volumes are needed where: 
Electro-statics: Volume Charge is assigned. 
Magnetostatics: Volume Current is assigned. In regions containing non-linear materials especially where the material is partially saturated. 
Time Harmonic Magnetics: Volume current is assigned.
In regions containing non-linear materials especially where the material is partially saturated 

57. Subvolume Density
Regions where there is a uniform source applied (volume currents and volume charges ) do not require any special consideration with respect to subvolume density. Because the source here is uniform, there is no consideration for resolution in the solution.
Increase density:
In consideration for what is being calculated.
Forces, torques or flux linkage on a coil.
For non-linear problems:
Change in field and transition from non-saturated to saturated material within a region

58. Symmetry
Symmetry occurs when you have mirror symmetry across one or more of the principal geometry planes.
If the real and equivalent current sources are mirrored across the symmetry plane, this is termed “Symmetry”, when they are mirrored but with opposite polarity, this is termed “Anti-Symmetry”.

59. Symmetry
Image on left exhibits “Symmetry” across the X=0 plane and “Anti-Symmetry” across the Y=0 and Z=0 planes.

60. Symmetry
When you have permanent magnets, the definition of symmetry is opposite to that of currents.
The image on the right shows “Anti-Symmetry” across the Y=0 plane and “Symmetry” across the Z=0 plane for permanent magnets. Z Y X

61. Periodicity
Periodicity occurs when the model exhibits a repetitive pattern along one or the principal axes or rotationally about one of the principal axes.
When the sources repeat themselves with the same polarity, this is termed “Periodic”. When the sources repeat with every the polarity of every second source reversed, this is termed “Anti-Periodic”.
There is no difference in the definition of “Periodic” and “Anti-Periodic” for permanent magnets.

62. Periodicity
Image on right shows magnetic coupling with arrows denoting direction of magnets

63. Periodicity
Two possibilities are 5 sections with “Periodic” setting or 10 sections with “Anti-Periodic” setting.

64. Symmetry and Periodicity
Post-processing is performed by deriving the sources in the image space from those in the modeled space.
Solution time is saved by accumulating the solution only in the modeled section.

65. Analysis Solver Setup Plot Types Figures of Merit
Solution Verification
Batch Processing and Parametrics

66. Analysis – Solver Setup
Matrix Solver Type – Leave as Auto
Accuracy Speed Factor Most cases = 1 Very Thin models may require increase.
Nonlinear Convergence Criteria – Most cases .03 is adequate. Very nonlinear  .01

67. Analysis – Plot Types
Analysis Viewer Dialog Change quantity to be displayed Change vector component Change plot type

68. Analysis – Graphs
Options Graph on Lines Segments, or on a Surface Number of evaluation points for the graph

69. Analysis – Autograph Utility
Legend
Plot curve with data points

70. Analysis – Autograph Utility
File menu to print graph or save data
Graph menu to zoom or pan on the graph.
Data menu to show or hide the graph data.

71. Analysis – Autograph Utility
Right click on a curve or the legend entry for a curve to display the Curve Operations menu.
Interesting features are Differentiation and Integration operations on the curve.
Use Curve Attributes to change color and data marker.
Use Hide to hide curves, to clarify plots with multiple curves.

72. Analysis – Contour Plots
Reference geometry Plotting grid density
Color fill on/off
Number of Contours or Bands to plot

73. Analysis – Contour Plots
Place a legend for the plot. Integrate the value of the scalar plot over the surface or plane.

74. Analysis – Arrow Plots
Reference geometry Plotting grid density Scale arrow size to field magnitude on/off
Number of Levels to plot

75. Analysis – Arrow Plots
Place a legend for the plot

76. Analysis – Figures of Merit
Calculate: Force/Torque on a real part of the model. Force/Torque on parts acting as a test coil Flux Linkage Inductance

77. Analysis - Solution Verification
Simplest Kind: Solve once (Perform some “sanity checks”)  Perform calculation     Increase elements    Solve again   
Until change in
calculated value
is less than
some criteria

78. Analysis - Solution Verification
“Reality Checks” Electrostatics
Computed Voltage vs. Assigned Voltage. Electric field inside closed conductors is zero. E•dl = V for known separation of potentials. Fundamental boundary conditions (Dn).
Magnetics Force/torque balance. Amperes Circuital Law (H•dl = I). Gauss’ Law - total flux crossing a closed path is zero. Fundamental boundary conditions (Ht).

79. Analysis - Solution Verification
“Reality Checks” (cont’d) Eddy Current/Time Harmonic Total current induced in plane = 0. Fundamental boundary conditions (Ht and Et) . Assigned current vs. integration of skin effect current density.

80. Batch Processing
Most useful to solve a set of distinctly different models, or to perform several operations on one model.
Batch mode is set from Utilities menu, then all commands and entries are recorded.
Batch files can be edited in a text editor and rerun. The usual method is to create the batch file in the program and edit rather than start from scratch.

81. Parametric Solver
Analyze a range of values for a particular aspect of the design.
Geometry, materials and currents can all be defined as parameters to be varied during the analysis.

82. Output
Obtaining Numerical Data
Exporting Visualizations

83. Numerical Data Generate text files of figures of merit.
Generating data from a graph or plot.
Generating output from a file of (x,y,z) coordinates.

84. Exporting Visualizations
Exporting Bitmap files: Generate image Add legends, text, etc. Select Utilities > Export > Image … Image saved as bitmap (.BMP) file

85. Exporting Visualizations
Generating Animations Create a set of images to include in the animation using the method outlined for saving images. Select Utilities > Export > Animation … Add all of the bitmaps wanted in the animation. Select Open from the file selection dialog. You can then save the animation as a .avi file.
HINT: When generating animations from contour or arrow plots, use the User Range setting on the dialog to maintain a constant reference.