WORKSHOP 4
Applying Loads and Boundary Conditions
Objectives: ■ Apply Constraints to the clevis. ■ Define a Field to describe a load distribution. ■ Use the Field to define a Variable Load.
MSC.Nastran 120 Exercise Workbook
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MSC.Nastran 120 Exercise Workbook
Loads and B/C’s on a Clevis
WORKSHOP 4
Model Description: Using the clevis model, apply Constraints and a Spatially Varying Load. The base of the clevis is Fixed and a quadratic Load Distribution of Fy=-100(1-x2) will be applied to the model. Figure 4.1 illustrates the loading conditions for the model.
Figure 4-1
Fixed
y x z
Apply a Spatially Varying Load to the bottom faces of the holes. Fx = Fz = 0 Fy = -100(1-x2)
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Suggested Exercise Steps: ■ Open the database, clevis.db. ■ Create a spatially varying vector field named quadratic_load. ■ Apply constraints to the model. ■ Define a variable load using a field.
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MSC.Nastran 120 Exercise Workbook
Loads and B/C’s on a Clevis
WORKSHOP 4
Exercise Procedure: 1.
Open the database, clevis.db. File/Open... Existing Database Name:
clevis.db
OK NOTE: Whenever possible, toggle off the ❑ Auto Execute option by left clicking the check box. 2.
Create a spatially varying Vector Field.
◆ Fields Action:
Create
Object:
Spatial
Type:
PCL Function
Field Name:
quadratic_load
Field Type:
◆ Vector
Second Component:
-100*(1-’X**2)
Apply 3.
Constrain the model.
◆ Load/BCs Action:
Create
Object:
Displacement
Method:
Nodal
New Set Name:
clamped
Input Data... Translation < T1 T2 T3 >
< 0, 0, 0>
OK Select Application Region...
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◆ Geometry
Geometry Filter: .
Surface or Face To make entity selection easier, switch to a Front View using an icon on the toolbar. Front view Changing the Picking preference will also help in selecting the application region for the next step. Preferences/Picking... Rectangle/Polygon Picking:
◆ Enclose entire entity
Close Turn off entity labels. Hide labels Drag the left mouse button to use a Rectangle Selection for applying the constraint. Figure 4.2 highlights the Application Region for constraining the model Figure 4.2
T Z 1
Y Z
X
Add 4-6
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Loads and B/C’s on a Clevis
WORKSHOP 4
OK Apply 4.
Create an applied load named vertical_load, which uses the quadratic_load field. Apply it to the solid faces along the bottom half of the holes.
◆ Load/BCs Action:
Create
Object:
Force
Method:
Nodal
New Set Name:
vertical_load
Input Data... Force
f:quadratic_load
OK Select Application Region... Be sure that the Surface icon is still highlighted in the Select Menu. Click in the Select Geometry Entities databox, and select the Surfaces for the load. Use the Polygon Pick method to select the Solid Faces that bound the bottom half of the holes, as shown in Figure 4.3. Figure 4.3 123
T 123
Z
R
1
123 Y Z
X
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Add OK Apply Vector markers representing the Applied Load will appear as shown in the Figure 4.4. Figure 4.4
123
T 123
0.
50.00
Z 1 100.0
50.00 R 0.
123 Y Z
5.
X
Display both the Constraint and Force on the finite element model. Display/Load/BC/Elem. Props...
■ Show on FEM Only Apply Cancel
◆ Load/BCs Action: Assigned Load/BCs Sets:
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MSC.Nastran 120 Exercise Workbook
Plot Markers Displ_clamped Force_vertical_load
Loads and B/C’s on a Clevis
WORKSHOP 4
Group Filter
◆ Current Viewport
Select Groups
default_group
Apply The Loads and Constraints should be displayed at nodal locations as shown in the Figure 4.5. Figure 4.5
123 123 123 T 3.805 6.699 14.64 25.000. 0. 30.86 50.00 50.00 67.62 67.62 Z 81.19 90.57 R 81.19 90.57 96.31 1 99.19 99.19 96.31 100.0
123 123 123 123 123 123
Y Z
6.
X
Since the markers for the load all have the same length, scale the markers to show the force distribution. Display/Load/BC/Elem. Props...
❑ Show LBC/El. Prop Vectors Vectors/Filters... ◆ Scaled-Model Relative Apply Cancel
Quit MSC.Patran after finishing this exercise.
MSC.Nastran 120 Exercise Workbook
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MSC.Nastran 120 Exercise Workbook