1. WORKSHOP 11 SPACECRAFT FAIRING

3. Problem Description
In this exercise, a spacecraft fairing will be constructed. Curves and surfaces will be used to define the fairing geometry. The finite element model will consist of 2-dimensional elements with 1-dimensional elements applied at various edges of the geometry. The 1-dimensional elements will represent stiffeners for the structure.

4. Workshop Objectives
Learn to use Groups and Lists

5. Suggested Exercise Steps
Create a new database called fairing.db and set the model preferences.
Create the model geometry.
Create the mesh seeds for the model.
IsoMesh the model using Quad4 topology.
Check the free edges, equivalence the model, and then check the free edges again.
Create a new group called FEM that contains only the finite elemental model. Then post only the FEM group.
Create two material properties, alum_1 and alum_2.
Create two fields, one for temperature and the other for thickness.
Create element properties.
Create a temperature boundary condition.
Create a series of lists containing elements that satisfy these following requirements: 1) the elements are made up of the alum_1 material, 2) the elements are greater than 0.98 in thickness, and 3) the elements have a temperature greater than degrees.
Intersect lists a and b to produce a list of elements that satisfy the first two conditions.

6. Suggested Exercise Steps (Cont.)
Create another list that satisfies the third condition.
Intersect the new list with the other list to produce a group of elements that satisfy all three conditions. Then, place these elements in a separate group.
Post the group containing the elements produced in step 14.
Create 2 new groups, each containing elements with different property sets.
Change the display attributes for each group.
Post each group separately, then post both groups together.

7. Step 1. Create New Database
Create a new database and set the
model preferences.
a. File : New.
b. Enter fairing for the File Name.
c. Click OK.
d. Set the Tolerance to Default.
e. Make sure that the Analysis Code
and Analysis Type are set to
MSC.Nastran and Structural,
respectively.
f. Click OK. e f b c

8. Step 2. Create Model Geometryf g
Create the points and curves that
represent the outline of the fairing.
a. Geometry : Create / Point / XYZ.
b. Enter [30 0 0] under Point
Coordinates List and click
Apply.
c. Geometry : Create / Curve / XYZ.
d. Enter < > and [ ]
under Vector Coordinates List
and Origin Coordinates List,
respectively.
e. Click Apply.
f. Click on Show Labels icon.
g. Click on Point Size icon to
increase the point size.
h. Geometry : Create / Curve / Point.
i. Click on Point 1 under Starting
Point List and click on Point 2 for
Ending Point List.
j. Click Apply. a h c d b i j e

9. Step 2. Create Model Geometry (Cont.)
Illustrated here are curves that represent the basic geometry for the fairing. These curves will be revolved 360º in order to get the final model.

10. Step 2. Create Model Geometry (Cont.)
Create the fairing by revolving
curves 1 and 2 about the fairing’s
vertical center line.
a. Geometry : Create /
Surface / Revolve.
b. Enter Coord 0.2 for Axis
c. Enter 360 for the Total
Angle.
d. Click on Curve 1, then click
on Curve 2.
e. Viewing : Angles.
f. Enter under Angles.
g. Click Apply. b c f d g

11. Step 2. Create Model Geometry (Cont.)b
Change the display preferences
in order to get a clearer visual of
the model.
a. Display : Geometry…
b. Enter 3 for Number of
Display Lines
c. Click Apply, then Cancel. c

12. Step 3. Create Mesh Seeds a b c Create a finite element mesh
so that 4 node Quad elements
are created every 10° along the
circumferential edges.
a. Elements : Create / Mesh
Seed / Uniform.
b. Select Number of
Elements and enter 36
for the Number.
c. Select the top
circumferential edge of
the fairing(Surface 1.3). b c

13. Step 3. Create Mesh Seeds (Cont.)
In the vertical direction (y-direction),
define a smoothly transitioning mesh
density. The elements along the top of
the cylinder are 2.5 times as large as
those along the bottom edge (tapered
end) of the fairing.
a. Elements : Create / Mesh Seed /
One Way Bias.
b. Select L1 and L2 and enter 7 and
10 for L1 and L2, respectively.
c. Select Curve 1.
d. Elements : Create / Mesh Seed /
e. Select L1 and L2 and enter 4 and
7 for L1 and L2, respectively.
f. Select Curve 2. a d b e c f

14. Step 4. Create a Mesh for the Model
Now that the mesh seeds have
been created, mesh the model
using Quad4 topology.
a. Elements : Create / Mesh
/ Surface.
b. Select Quad, IsoMesh,
and Quad4.
c. Rectangular pick the
entire model and click
Apply.
d. Remove the display lines
by clicking the on the
Display lines icon.
e. Remove the labels by
clicking the Hide labels
icon.
f. Decrease the point-size
by clicking on the Point
Size icon. a b c

15. Step 4. Create a Mesh for the Model (Cont.)
Mesh the horizontal (circumferential)
edges of each surface with two-
noded bar elements.
a. Click on Plot/Erase icon and
click on Erase under FEM.
b. Click OK.
c. Elements : Create / Mesh /
Curve.
d. Set Topology to Bar2
e. Shift select the 3 curves (as
indicated).
f. Click Apply. c d e e b f

16. Step 5. Observe the Free Edgesa
Check the free edges of the model,
equivalence, and then check the
free edges again.
a. Click on the Plot/Erase Icon.
b. Under FEM, click Plot.
c. Elements : Verify / Element /
Boundaries.
d. Select Free Edges under
Display Type.
e. Click Apply.
f. Elements : Equivalence / All /
Tolerance Cube.
g. Click Apply.
h. Repeat steps c through e. c d e f g

17. Step 6. Create a New Group a b c d e Replot the FEM and create a group
called FEM containing only the finite
element model. Post only this new
group to the viewport.
a. Group : Create…
b. Enter FEM for the New Group
Name.
c. Select Unpost All Other
Groups.
d. Change Group Contents to
Add All FEM.
e. Click Apply. b c d e

18. Step 7. Create Material Properties
Create the first material for the
model. Material alum_1 will be
applied to the top(cylindrical) portion
of the fairing.
a. Materials : Create / Isotropic /
Manual Input.
b. Enter alum_1 for the Material
Name.
c. Click on Input Properties.
d. Select Linear Elastic and
enter 1.05E7, 0.33, and
2.6E-4, for Elastic Modulus,
Poisson Ratio, and Density,
respectively.
e. Click OK.
f. Click Apply. d b c e f

19. Step 7. Create Material Properties (Cont.)
Create the second material for the
model. Material alum_2 will be
applied to the bottom(tapered)
portion of the fairing.
a. Materials : Create / Isotropic /
Manual Input.
b. Enter alum_2 for the Material
Name.
c. Click on Input Properties.
d. Select Linear Elastic and
enter 1.18E7, 0.33, and
2.4E-4, for Elastic Modulus,
Poisson Ratio, and Density,
respectively.
e. Click OK.
f. Click Apply. d b c e f

20. Step 8. Create Fields a b c Define a field that represents the
varying thickness.
a. Fields : Create / Spatial / PCL
Function.
b. Enter thickness for the Field
Name.
c. Enter 1.5-’Y/160 for the Scalar
Function and click Apply. b c

21. Step 8. Create Fields a d b e c f
Plot the function defined in the field.
Field : Show
Select thickness as the field to show.
Click Specify Range.
Enter for the maximum and 20 for the number of points.
Click O.K.
Click Apply. d b e c f

22. Step 8. Create Fields a b c d Delete the plot.
XY Plot : Delete / XYWindow
Select XY Result Window.
Click Apply.
Choose Yes to delete the result window. a b c d

23. Step 8. Create Fields a b c Define a field that represents the
varying temperature distribution.
a. Fields : Create / Spatial / PCL
Function.
b. Enter temperature for the
Field Name.
c. Enter (150.0/160.0)*’X
for the Scalar Function and
click Apply. b c

24. Step 8. Create Fields a b d e c f
Plot the function defined in the field.
Field : Show
Select temperature as the field to show.
Click Specify Range.
Enter 50.0 for the maximum and 10 for the number of points.
Click O.K.
Click Apply. b d e c f

25. Step 9. Create Element Propertiesf
Create two element properties
which include the material
definitions and varying thickness.
a. Properties : Create / 2D /
Shell.
b. Enter prop_1 for the
Property Set Name.
c. Click on Input Properties.
d. Click on the Select
Material icon.
e. Select alum_1 from the
Select Material list box.
f. Click on the Front view
icon. a d b c e

26. Step 9. Create Element Properties (Cont.)
Finish creating the first property set.
a. Set the thickness type to
Element Nodal and click on
the Select Field icon.
b. Select thickness as the Scalar
Spatial Field.
c. Click OK.
d. Click on Select Members and
click on the Shell Element
icon.
e. Select the top(cylindrical)
portion of the fairing by
dragging a box around the
desired section (as indicated
on next page).
f. Click Add, then Apply. a d e b c f

27. Step 9. Create Element Properties (Cont.)
Illustrated here is the desired application region for the first property set.

28. Step 9. Create Element Properties (Cont.)
Create the second property set.
a. Properties : Create / 2D /
Shell.
b. Enter prop_2 for the Property
Set Name.
c. Click on Input Properties…
d. Click on the Select Material
Icon.
e. Select alum_2 from the
Existing Materials.
f. Click on the Select Field Icon
g. Select thickness from the
Existing Fields box.
h. Click OK.
i. Click on Select Members and
select the bottom(tapered)
portion of the fairing by
dragging a box around it(as
indicated on next page).
j. Click Add, then Apply. a d f b c i g e h j

29. Step 9. Create Element Properties (Cont.)
Shown here are the elements for the desired application region of the second property set.

30. Step 10. Create Temperature Boundary Conditions
Define the model’s varying temperature
distribution.
a. Loads/BCs : Create / Temperature
/ Nodal.
b. Enter temp for the New Set
Name.
c. Click on Input Data.
d. Click on Temperature and select
temperature from the Spatial
Fields.
e. Click OK.
f. Click on Select Application
Region.
g. Under Geometry Filter, select
FEM.
h. Click on Application Region and
select the entire model.
i. Click Add, then, OK
j. Click Apply. g a d h b i e c f j

31. Step 10. Create Temperature Boundary Conditions (Cont.)
Turn off the temperature labels in
order to get a better visualization of
the model.
a. Display : Load/BC/Elem.
Prop…
b. Under Loads/BC’s remove
check under Temperature.
c. Click Apply, then Cancel. c

32. Step 11. Create Lists a b c d e
Use Lists and groups to filter then group
the quad elements that have the following
attributes:
Material : alum_1
Thickness : > 0.98
Temperature : >230.0
a. Tools : List / Create…
b. FEM / Element / Attribute
c. Under Attribute, select Material.
d. Under Existing Materials, select
alum_1.
e. Set the Target List to “A” and click
Apply. c d
The contents of List A compose of elements that satisfy the first condition; they are made up of the alum_1 material. e

33. Step 11. Create Lists (Cont.)
Define List B to include only the
Quad elements that have a
thickness greater than 0.98.
a. Properties : Show.
b. Under Existing Properties,
select Thickness.
c. Set Display Method to
Scalar Plot.
d. Select Current Viewport,
select FEM and click Apply. b c d
Shown above is a fringe plot the model by thickness. Those elements that are thicker than 0.98 will be included in the next list.

34. Step 11. Create Lists (Cont.)b
After defining the list parameters,
add the elements greater than 0.98
in thickness to list B.
a. Tools : List / Create…
b. FEM / Element / Attribute.
c. Under Attribute, select Fringe
Value.
d. Under Fringe Tools, select
default_Fringe.
e. Change the inequality to > and
enter 0.98.
f. Select “B” for the Target List.
g. Click on Apply. c d
The contents of List B include all elements thicker than 0.98. e f g

35. Step 12. Intersect Lists a b c Intersect Lists A and B and replace
the contents of List A with the
elements found in the intersection.
a. Tools : List / Boolean…
b. Click on the Intersect icon.
c. Click on Replace A. b c
The new List A is composed of elements that satisfy both requirements: they are made up of alum

36. Step 13. Create More Lists a b c d
Perform a final classification of the
elements. Isolate those elements
that satisfy the third condition of the
applied temperature load >
a. Loads/BCs : Plot Contours /
Temperature.
b. Select temp from the
Existing Sets.
c. Select Temperature under
Select Data Variable.
d. Select the FEM group and
click Apply. b c d

37. Step 13. Create More Lists (Cont.)b
Clear the contents of List B and add the
values obtained from the final classification.
a. Tools : List / Create.
b. FEM / Element / Attribute.
c. Select Fringe Value and
default_Fringe for Attribute and
Fringe Tools respectively.
d. Change the inequality to > and enter
230.0.
e. Select “B” for the Target List.
f. Click on Clear on the List B form
g. Click Apply on the List Create
form. f c d e g

38. Step 14. Intersect Lists Again
Lists A and B will be intersected
again to create a List C. This list will
contain the elements that satisfy all
three conditions. The contents of
List C will then be placed into a new
group called common_quads.
a. Tools : List / Boolean…
b. Click Clear.
c. Click on the Intersect icon(It
may be necessary to click on
any of the other icons first).
d. Click on Add To Group…
e. Enter common_quads for the
Group Name.
f. Click Apply, then Cancel. c b d e f

39. Step 15. Post Group a d b c Post the common_quad group.
This is the group of elements
that satisfy all three of the
conditions defined earlier.
a. Group : Post…
b. Select the
common_quads group
under Select Groups to
Post.
c. Click Apply, then
Cancel.
d. Click on the Iso 1 view
icon. b c

40. Step 15. Post Group (Cont.)
This is the Iso 1 view of the elements in the common_quads group. These are all the elements that satisfied all three conditions.

41. Step 16. Create Two New Groupsb a f c
Create two new groups, prop1_group
and prop2_group. Then, change the
display attributes for each group.
a. Click on the Reset Graphics
icon.
b. Group : Create…
c. Create / Property Set.
d. Enter prop1_group for the
Group Name.
e. Select prop_1 under Property
Sets.
f. Click Apply.
g. Repeat steps b through f
entering prop2_group for the
Group Name and selecting
prop_2 under Property Sets. d e f

42. Step 17. Change the Display Attributes
Set the entity coloring and labeling to Group mode
and then change the display attributes for each of
the two new groups.
a. Display : Entity / Color / Label / Render…
b. Select Group under Entity Color and
Labeling.
c. Select the prop1_group under the Target
Group(s).
d. Select HiddenLine for the Render Style
and select dark blue for the Shade Color.
e. Click Apply.
f. Select the prop2_group for the Target
g. Select Wireframe for the Render Style and
select red for the Shade Color.
h. Click Apply, then, Cancel. c f g d h e

43. Step 18. Post Groups b a c d Change views and post the prop1_group.
a. Click on the Iso 3 view icon.
b. Group : Post…
c. Under Select Groups to
Post, select
d. Click Apply. c d

44. Step 18. Post Groups (Cont.)a
Post only the prop2_group.
a. Group : Post…
b. Under Select Groups to
Post, select
prop2_group.
c. Click Apply. b c

45. Step 18. Post Groups (Cont.)a
Post both the prop1_group
and the prop2_group.
a. Group : Post…
b. Under Select
Groups to Post,
select both
prop1_group
and
prop2_group.
c. Click Apply. b c