Mid-Surface Creation
Training Manual
– Reduces 3D geometry of constant thickness to a simplified “shell”
representation
t ti
– Automatically places surface body at mid point between 3D face pairs
– Allows shell element type meshing in Simulation
Mid-Surface representation
3D Model
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
Desig
gnModele
er
• Mid-Surface Tool:
ANSYS, Inc. Proprietary
Inventory #002496
5-71
…Mid-Surface Creation
Training Manual
Desig
gnModele
er
• Manual Mid-Surface creation:
– With “Face Pairs”, “Apply/Cancel” buttons
active,
ti
choose
h
the
th face
f
pair
i
– Note the order of selection determines the
surface normal direction
– Notice the first surface picked is displayed
y in
purple, the second is shown in pink
1st
Pick
Normal
Direction
2nd
Pick
Resulting
Surface Body
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-72
…Mid-Surface Creation
Training Manual
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Desig
gnModele
er
• Selection Note: While in select mode (apply/cancel active) the color
scheme described earlier is in effect. When the selection is finalized the
selected pairs are displayed in dark and light blue
blue.
Inventory #002496
5-73
…Mid-Surface Creation
Training Manual
– Multiple surface pairs may be selected for a single
mid-surface
id
f
operation,
ti
however
h
th
they mustt be
b
selected as opposing pairs (see picture)
– Adjacent face pairs will be grouped together if within
the “Thickness Tolerance” (see below)
1
2
3
5
Desig
gnModele
er
• Mid-surface details:
4
6
T2
T1
If │T1 – T2│ < Thk Tol: surfaces are grouped
Mid Surface
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-74
…Mid-Surface Creation
Training Manual
– If gaps exist in adjacent face pairs they will be sewn together within the
“S i T
“Sewing
Tolerance”
l
”
– Sewing Tolerance: If Gap < Sewing Tol: surfaces are grouped
Desig
gnModele
er
• Mid-surface details:
Gap
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-75
…Mid-Surface Creation
Training Manual
– Switching the “Selection Method” from Manual to Automatic exposes several
additional
dditi
l options
ti
• Bodies to search: allows limiting search to visible bodies, selected bodies or all bodies
• Minimum and maximum threshold sets search range (thickness) for face pairs
• Extra trimming provides options for situations where trimming problems with the surface
b d occur (d
body
(described
ib d llater)
t )
• Preserve bodies allows you to save the solid bodies from which surfaces are created
(default is No)
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Desig
gnModele
er
• Automatic mid-surface creation:
Inventory #002496
5-76
…Mid-Surface Creation
Training Manual
– Solid body is 5 mm thick
– When the mid-surface tool is inserted
we switch to “Automatic”
• Note: the “Face Pairs” field used in
manual mode is left “0”
– With a constant thickness throughout
we set the min/max threshold values
to 5 mm
– Using
g the drop
p down choice we
choose “Find Face Pairs Now? = Yes”
Desig
gnModele
er
• Automatic mid-surface example:
– Continued
C ti
d...
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-77
…Mid-Surface Creation
Training Manual
– When the search is complete the number of pairs
d t t d is
detected
i lilisted
t d iin th
the d
details
t il and
d di
displayed
l
d graphically
hi ll
Desig
gnModele
er
• Automatic mid-surface example (continued):
– Mid surface creation is completed by “Generating” the
surface body
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-78
…Mid-Surface Creation
Training Manual
Desig
gnModele
er
• Mixing manual and automatic
selection modes:
– IIn some cases it is
i convenient
i t tto
make an initial surface pair selection
and let the automatic method
complete the process
– Example:
• The model shown here contains 2
different thicknesses
• In this case we’ll select, (manually) a
face pair of each thickness
• We will then allow the auto face
detection to complete the selection
2 mm
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
1 mm
Inventory #002496
5-79
…Mid-Surface Creation
Training Manual
Desig
gnModele
er
• We begin by manually
selecting the 2 face
pairs shown here
• Note the face pairs selected
contain a 1 mm and a 2 mm
pair
i
• We now change the selection method to
“Automatic”
– Note the min/max threshold values are
automatically defined based on our manual
selections
• Continued . . .
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-80
…Mid-Surface Creation
Training Manual
Desig
gnModele
er
• We now activate “Find Face Pairs
Now”
–N
Notice
ti th
there are 2 options
ti
(d
(due tto
the pre selection of face pairs)
– Yes-Add to Face Pairs: adds auto
detected faces to the existing face
pairs selected
– Yes-Replace Face Pairs: will use
only the auto detected faces
• Choosing to add face pairs allows
us to complete the operation
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-81
…Mid-Surface Creation
Training Manual
– In this case the maximum threshold was
increased to intentionally detect unwanted
surfaces
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Desig
gnModele
er
• Adding to, removing from or modifying
automatic surface selection:
• Examples:
Inventory #002496
5-82
…Mid-Surface Creation
Training Manual
• In this case we can choose “Remove Face
Pairs” then select one of the faces to be
removed
Desig
gnModele
er
• Clicking in the “Face Pairs” field activates
selection mode (note the colors change to
indicate this)
• RMB in the graphics window provides the
optional selection modes
– When selection is complete “Generate” to
update the model
• Note when removing face pairs, selecting one
of the faces will remove the pair
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-83
…Mid-Surface Creation
Training Manual
– In cases where trimming problems occur
th
there
are severall options
ti
available
il bl tto
attempt corrections
– Example:
• Using the previous model we generate the
surface model without removing the
unwanted face pairs
• Since the pairs created result in T
junctions, trimming problems occur
Desig
gnModele
er
• Trimming options:
• Notice the mid-surface branch in the tree
is displayed with a yellow check indicating
there is a problem
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-84
…Mid-Surface Creation
Training Manual
– The default behavior is to intersect any
untrimmed surfaces with the original solid
body
– Other options:
Delete
untrimmed
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
Desig
gnModele
er
• Using the RMB option we can “Show
Problematic Geometry”
• The resulting plot shows regions where
trimming problems have occurred
No Extra
Trimming
ANSYS, Inc. Proprietary
Inventory #002496
5-85
Mid Surface Creation
Workshop 5-4
54
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-86
Workshop 5.4, Mid-Surface Creation Overview
– Familiarize users with mid-surface
mid surface capabilities
that are new to Workbench 10.0
– Demonstrate manual and automatic pair
detection
– Demonstrate surface extension for interfaces
Desig
gnModele
er
• Goal
Training Manual
• Model Description
– 2 part bracket with consistent cross sections
– Since
Si
the
th model
d l has
h consistent
i t t cross sections,
ti
shell elements will be used to mesh the model.
This saves time and CPU resources.
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-87
Workshop 5.4, Mid-Surface Creation
Training Manual
Open > Design Modeler Geometry and Browse to > …\bracket_mid_surface.agdb
2. In the Model Tree, note that there are 2 separate parts:
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Desig
gnModele
er
1. From the workbench launcher, select
Inventory #002496
5-88
Workshop 5.4, Mid-Surface Creation
Training Manual
Menu Bar > Selection Filter – Edges.
g tools to verify
y these thicknesses.
Use the status bar measuring
Smaller Body Thickness = 1mm
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
Desig
gnModele
er
3. Each body of this model has different thicknesses. These thickness dimensions will
be entered into the Maximum Threshold and Minimum Threshold fields in the Details
of the MidSurf object
object.
Larger Body Thickness = 2mm
ANSYS, Inc. Proprietary
Inventory #002496
5-89
Workshop 5.4, Mid-Surface Creation
Training Manual
Desig
gnModele
er
4. Insert a mid-surface object
Main Menu > Tools > Mid-Surface
5. In the Details of MidSurf1, change the
Selection Method to Automatic
6. Enter the Minimum Threshold of 1mm
and Maximum Threshold of 2mm
obtained from step 3.
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-90
Workshop 5.4, Mid-Surface Creation
Training Manual
Desig
gnModele
er
7. Set “Find Face Pairs Now?” to “Yes”
8. The Face Pair Automatic Selection method
will select 11 face pairs. However, the
automatic selection method has incorrectly
identified the following features:
a) A face pair that is not needed.
b) A face pair whereby the normal will need
to be reversed
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-91
Workshop 5.4, Mid-Surface Creation
Training Manual
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Desig
gnModele
er
9. Editing Face Pairs
– The face colors help to indicate the current mode
when adding or removing face pairs from the
selection set.
Inventory #002496
5-92
Workshop 5.4, Mid-Surface Creation
Training Manual
11. In the Graphics Window
-
Zoom as needed.
Click on the face to Remove.
Right click to display the Context menu.
Select : Remove Face Pairs.
Desig
gnModele
er
10. To Remove Face Pairs, Click in the
Details of MidSurf1 – Face Pairs to
enter the selection mode (Apply /
Cancel).
12. Note how the context bar indicates
“Select
Select face pairs to remove
remove”.
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-93
Workshop 5.4, Mid-Surface Creation
Training Manual
14. In the Graphics Window
- Zoom as needed.
- Click on the face to Reverse.
- Right click to display the Context menu.
- Select : Reverse Face Pairs
Desig
gnModele
er
13. To Reverse Face Pairs, Click in the Details
of MidSurf1 – Face Pairs to enter the
selection mode (Apply / Cancel)
Cancel).
15. Note how the context bar indicates “Select
face pairs to reverse”
Note that the Reverse Face pair mode operates as a toggle.
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-94
Workshop 5.4, Mid-Surface Creation
Training Manual
Desig
gnModele
er
16.
Generate the Mid-Surface
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-95
Workshop 5.4, Mid-Surface Creation
Training Manual
Desig
gnModele
er
17. Now, instead of two solid bodies,
there are four surface bodies. They
cannot be combined into a single
body because the "T" intersections
would cause it to be non-manifold.
Also, in the final figure below, you
will see that the resulting surface
bodies for the back brace are
automatically extended/trimmed to
meet the main part of the bracket,
as these were all part of one solid
y originally.
g
y However,, the front
body
brace was a separate body, so it is
not automatically extended.
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-96
Workshop 5.4, Mid-Surface Creation
Training Manual
Insert a Surface Extension object. Main Menu > Tools > Surface Extension
Desig
gnModele
er
18. The Surface Extension feature can be used to extend the front brace edge so that
it meets the main bracket surface.
Note: It may be helpful to suppress
May
11, other
2007
the
bodies.
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-97
Workshop 5.4, Mid-Surface Creation
Training Manual
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Desig
gnModele
er
19. Click in the Details of SurfaceExt1 – Edges to enter the selection mode and
select both edges (Apply / Cancel).
Select: Apply
Inventory #002496
5-98
Workshop 5.4, Mid-Surface Creation
Training Manual
21 Generate
21.
– Surface edges are now extended.
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Desig
gnModele
er
20. In the Details of SurfaceExt1 – Extent > Change the Extent to “To Next”.
Inventory #002496
5-99
Workshop 5.4, Mid-Surface Creation
Training Manual
Desig
gnModele
er
•
Alternate Method for determining
Minimum and Maximum thresholds.
- In this example geometry, it was
relatively easy to identify and measure the
solid body thicknesses. In practice, it may
be preferable to select the face pairs first,
then allow the program to calculate the
Minimum and Maximum thresholds.
22. Details of MidSurf1
Set: Selection Method > Manual
23. Select: Face Pair Selection mode
(Apply/Cancel)
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-100
Workshop 5.4, Mid-Surface Creation
Training Manual
25. Then, CTRL key and select the face pairs
on the small bracket to represent
p
the 1mm
thickness.
•
Select: Face Pairs : Apply
•
Note that 2 Face Pairs are now in the selection
set. 1 Pair representing 2mm, the other
representing 1mm.
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Desig
gnModele
er
24. Hold CTRL key down and select the face
pairs on the large bracket to represent the
2mm thickness. Use the selection
rectangles in the lower left corner to
choose hidden faces).
Inventory #002496
5-101
Workshop 5.4, Mid-Surface Creation
Training Manual
Desig
gnModele
er
26. Select: Selection Method :
Automatic
• Note that Minimum Threshold and
Maximum Threshold have been
filled in automatically.
27 Find Face Pairs Now?
27.
> Yes – Add to Face Pairs
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Inventory #002496
5-102
Workshop 5.4, Mid-Surface Creation
Training Manual
May 11, 2007
© 2007 ANSYS, Inc. All rights reserved.
ANSYS, Inc. Proprietary
Desig
gnModele
er
28. The Face Pair Automatic Selection method has selected 11 face pairs which is
the same number from Step 8.
Inventory #002496
5-103