~Spur Gears ñ Static Stress Analysis with Linear Material Models.pdf
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Exercise A
Spur Gears
–
Static Stress Analysis with Linear Material Models
Beam and Brick Elements
Objective
:
Determine the stress distribution in the spur gears when a moment of 93.75 in-lb is
applied to the pinion.
Geometry
:
Use the
Exercise A
.dmit file located in the "Exercise A\input file" directory. The gears
are manufactured out of steel and are based on a diametral pitch of 8. There are 10 teeth
in the pinion, 24 teeth in the main gear and the width of both gears is 0.25 inches.
Loads
:
A moment of 93.75 in-lb will be applied to the pinion.
Constraints
:
A joint will be created at the center of the pinion.
The pinion will be constrained to only rotate about its center.
The main gear will be fully fixed at the shaft hole to simulate a locked condition.
Elements
:
Beam
Brick
Material
:
Steel (ASTM-A36)
Contact
:
Surface contact will be defined between the pinion and the main gear.
Exercise A Spur Gears
–
Static Stress Analysis with Linear Material Models
Finite Element Analysis in Practice Gear Design Supplement 1.00 02/20/2004
Exercise A Spur Gears
–
Static Stress Analysis with Linear Material Models
Solution
Opening the Model
The CAD Solid Model environment of FEMPRO is used to create a mesh on all solid models. You can
open CAD models from any of the CAD solid modelers or universal CAD formats that ALGOR supports.
Press the Windows
"Start"
button. Select the
"Programs"
pull-out menu and then select the
"ALGOR V14"
pull-out menu. Select the
"FEMPRO"
command. The ALGOR FEMPRO
application will now appear.
"Start: Programs:
ALGOR V14: FEMPRO"
Press the
"Open"
icon at the left of the
"Open"
dialog. Navigate to the Exercise A\input file directory
and change the
"Files of type"
drop-down box to the
"ALGOR Direct Memory Image Transfer Files"
option as shown in Figure 1. Then select the file Exercise A.dmit and press the
"Open"
button.
Figure 1: Select Type of File to Open
"OK"
A dialog will appear asking you to choose the
design scenario for this model. Press the
"OK"
button to accept the default of
"Single analysis:
Static Stress with Linear Material Models"
.
Finite Element Analysis in Practice Gear Design Supplement 1.00 02/20/2004
Exercise A Spur Gears
–
Static Stress Analysis with Linear Material Models
Meshing the Model
"Mesh: Create Mesh
…
"
If the
"Create Mesh"
dialog does not automatically
appear, use the
"Mesh: Create Mesh
…
"
command to
bring it up.
Press the
"Details >>"
button on the
"Create Mesh"
dialog to change the default mesh settings.
"Details >>"
"Options
…
"
"
button on the
"Create Mesh"
dialog to access additional meshing options.
Press the
"Options
…
15
Enter a value of
"15"
in the
"Angle"
field in the
"Edge
curve
refinement"
section
of
the
"Surface
Mesh
Options"
dialog as shown in Figure 2.
0.01
Enter a value of
"0.01"
in the
"Tolerance value"
field in
the
"Part matching"
section of the
"Surface Mesh
Options"
dialog as shown in Figure 2.
Figure 2: Surface Mesh Options
"OK"
Press the
"OK"
button on the
"Surface Mesh Options"
dialog to accept the changes.
"Mesh"
Press the
"Mesh"
button on the
"Create Mesh"
dialog to
create the mesh.
Mouse
Press the
button in the upper right corner of the
"Create
Mesh"
dialog to close it.
Finite Element Analysis in Practice Gear Design Supplement 1.00 02/20/2004
Exercise A Spur Gears
–
Static Stress Analysis with Linear Material Models
Defining Surface Contact
The default contact option of
"Bonded"
will be changed to
"Surface Contact"
. This type of contact will
prevent the surfaces from penetrating each other, but still allow them to pull away from each other with no
resistance.
Mouse
Right click on the
"Contact"
heading in the tree view
and select the
"Surface Contact"
command as shown in
Figure 3 below.
Figure 3: Setting the Contact Type
Using the Joint Creation Utility
The joint creation utility will be used to create a pin joint (i.e., a "spider-web" of beam elements) at the
location of the shaft hole in the pinion. The pin joint will facilitate constraining of the pinion to rotate
about its center and also the application of the moment load.
"View: Rotate"
Access the VIEW pull-down menu and select the
"Rotate"
command. Using the mouse, rotate the model
around to get a clear view of the shaft hole in the pinion.
Zoom and pan operations can also be used to get a closer
view.
"Selection: Shape: Point"
Access the SELECTION pull-down menu and select the
"Shape"
pull-out menu. Select the
"Point"
command.
This will allow you to select an object by clicking on it.
"Selection: Select: Surfaces"
Access the SELECTION pull-down menu and choose the
"Select"
pull-out
menu.
Select
the
"Surfaces"
command.
Click on one of the two surfaces for the shaft hole in the
pinion. The surface will turn to a magenta color to
indicate that it is selected.
Mouse
<Ctrl> Mouse
While holding down the <Ctrl> key, click on the second
surface of the shaft hole in the pinion. Both surfaces for
the hole should now be selected, as shown in Figure 4
below.
Finite Element Analysis in Practice Gear Design Supplement 1.00 02/20/2004
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~Spur Gears ñ Static Stress Analysis with Linear Material Models.pdf
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