Workshop 5.2
Prestressed Modal Analysis
Prestressed Modal Analysis
Workshop 5.2 - Goals
Workshop Supplement
• Specifically, we will load the link with a 4000 N tensile load
and compare the natural frequency to that of the unloaded
component.
ANSYS Workbench - Simulation
• Our goal is to simulate the modal response of the tension
link (shown below) in both a stressed and unstressed state.
March 29, 2005
Inventory #002216
WS5.2-2
Prestressed Modal Analysis
Workshop 5.2 - Start Page
From the launcher start Simulation.
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Choose “Geometry > From File . . . “
and browse to the file
“tension_link.x_t”.
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When DS starts, close the Template
menu by clicking the ‘X’ in the corner
of the window.
ANSYS Workbench - Simulation
•
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Prestressed Modal Analysis
Workshop 5.2 - Preprocessing
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–
“Units > Metric (mm, kg, MPa, C, s)
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2. Highlight the Environment branch, RMB and “Duplicate”.
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3. Rename the 2 environment branches as shown.
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ANSYS Workbench - Simulation
1. When the DS GUI opens choose the Metric mm unit system.
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RMB > Rename
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Prestressed Modal Analysis
. . . Workshop 5.2 - Preprocessing
In the “Unstressed” environment:
4. Highlight one of the inside faces of
one washer “RMB > Insert > Fixed
Support”.
5. Highlight the face on the rim of the
other washer “RMB > Insert >
Frictionless Support”.
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ANSYS Workbench - Simulation
•
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Prestressed Modal Analysis
Workshop 5.2 - Preprocessing
Workshop Supplement
•
Note: we will accept the default six (6)
modes for the Frequency Finder.
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7. Using the shift key, highlight the 2
boundary conditions just applied in the
Unstressed branch:
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– “RMB > Copy”.
8. Highlight the Prestressed branch:
ANSYS Workbench - Simulation
6. Highlight the Solution branch, “RMB >
Insert > Frequency Finder”.
– “RMB > Paste”.
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Prestressed Modal Analysis
Workshop 5.2 - Environment
Workshop Supplement
10. “RMB > Insert > Force”.
11. Enter “4000” in the Magnitude field.
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Note use the “Direction” field to
modify the force direction if
necessary to insure the load is tensile
(see below).
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ANSYS Workbench - Simulation
9. Reorient the model as necessary and
zoom in on the inside face of the
washer where the frictionless support
is applied to the rim.
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Direction Field
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Prestressed Modal Analysis
. . . Workshop 5.2 - Environment
Workshop Supplement
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13. Highlight the Model branch and Solve (note solving from the
Model branch will cause both environments to solve
sequentially).
ANSYS Workbench - Simulation
12. Highlight the solution branch in the Prestressed
environment, “RMB > Insert > Frequency Finder”.
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Prestressed Modal Analysis
Workshop 5.2 – Postprocessing
Workshop Supplement
Unstressed
Prestressed
ANSYS Workbench - Simulation
• When the solutions are complete expand the Frequency
finders and review the results from each.
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Prestressed Modal Analysis
Workshop 5.2 – Postprocessing
As shown below the prestressed results should show an
increase in frequencies.
– Note: the actual frequencies may vary slightly from those
shown due to meshing and machine differences.
ANSYS Workbench - Simulation
•
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Prestressed Modal Analysis
. . . Workshop 5.2 – Posprocessing
Although not a requirement, good practice recommends that we
include a stress calculation in our prestressed branch to insure
that the component does not fail due to the applied load.
14. Highlight the solution branch in the Prestressed environment,
“RMB > Insert > Stress > Equivalent (von-Mises)”.
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15. Once again issue a solve from this branch to update the new
result.
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ANSYS Workbench - Simulation
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Workshop Supplement
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WS5.2-11
Prestressed Modal Analysis
Workshop 5.2 - Postprocessing
By comparing the reported stresses to the material’s yield
values (Engineering Data) we can assess the component’s
performance with respect to the applied load.
– Note, it may be necessary to calculate other results
(deformation, strain, etc.) depending on the application in which
the part is used.
ANSYS Workbench - Simulation
•
Workshop Supplement
March 29, 2005
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WS5.2-12