Webcutter

Webcutter
1
Topics Covered
In this tutorial, you will learn following new things:
1.
2.
Set material Properties
Create Extruded Part
3.
4.
Verify Model
Modify Material Properties
5.
6.
Export Data to Excel
Create A step Function
You will need to download “link_geometry.zip” file to complete this tutorial
2
Problem Title
B4
B3
A2
O4
O2
This tutorial will describe in depth how to use ADAMS to determine the torque of the motor, bearing
forces, and the angular position, velocity, and acceleration of the links for the given problem.
Links are 2cm thick and made out of Al 6063. Link 2 is rotating at a rate of 60 rpm CCW.
3
What You Should Accomplish
If you are successful, you should end up with a simple working
webcutter model that illustrates bearing force, motor torque and angular
velocity/acceleration of your model.
4
Create New Model
Getting Started:
a.
Under the heading "How would you like to proceed", select the Create a new model radio button.
b.
Choose a Location to save your files
c.
Set Model Name as Webcutter
d.
Verify the Gravity text field is set to Earth Normal (-Global Y).
e.
Verify that the Units text field is set to MKS - m,kg,N,s,deg.
f.
Select OK.
a
b
c
d
e
f
5
Change Working Grid Settings
To edit the grid size:
a.
Click Settings menu, select Working Grid…
The Working Grid Settings window will appear
b.
Change the Spacing text fields in X and Y to (10mm)
c.
Click OK
d.
Click View Coordinate Window (F4)
a
b
d
c
Note: you should see a denser set of dots on your screen
6
Set Material Properties
a.
Click Build Menu Materials New
b.
A new window will appear, enter:
Name: .Webcutter.Al6063
Young Modulus: 214e6
Poissons Ratio: 0.33
Density: 2710
c.
Click OK
a
b
c
Note: If the density is not set the simulation will not run properly
7
Create Extruded Part
a.
Right click on Rigid body tool stack, select Extrusion tool
b.
Enter 0.02 in the Length text field
c.
Select Backward from Path: drop down menu
d.
Click points origin (0.0, 0.0, 0.0) (0.15, 0.15 0.0) (0.15, 0.0, 0.0) (0.0, 0.0, 0.0), right-click to
close
a
d
c
b
Note: When using a command the bar on the bottom will tell you what to do and you can always exit a command by
pressing the Esc key
8
Change View
a.
Right Click in the workspace and Select Iso <I> or Press Shift+I to view an isometric view.
a
Various other options and their shortcut keys are available in this menu. Spend some time experimenting with them
and then return to the front view (Shift+F)
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Rename
a.
Right-Click on part, select Part: PART_2 Rename
b.
Enter .model_1.link_2 in New Name text field
c.
Click OK
b
c
a
d.
Rename the Marker at the origin to .model_1.O2
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Modify Extrusion Points
a.
Right-click on the triangle, select Extrusion: Extrusion_1 Modify. a
b.
Click
c.
Click Read button next to File
d.
Browse the directory for the file link2.txt
e.
Click Open
f.
Click OK
g.
Click OK
next to Profile Points text field
d
b
g
e
c
f
Note: By starting our Triangle at the origin and normalizing the points about O2 for link 2, the origin and O2 coincide.
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Create a Marker
a.
Right click on Rigid body tool stack, select Marker tool
b.
Select Add to Part from Marker pull down menu
c.
Select Global XY from Orientation pull down menu
d.
Click Part_2 (0.04, 0.0, 0.0)
e.
Rename Marker .model_1.A2
a
b
c
d
Note: This is why the links were rotated to make OA horizontal for the input files.
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Add Revolute Joint
a.
Right click Joint tool stack, select Revolute joint
b.
Select 1 Location from Construction pull down menu
c.
Click on point link_2.O2
a
b
c
13
Add Motion
a.
Right Click on Motion Driver tool stack, select Rotational Joint Motion
b.
Enter (360D) in Speed text field
c.
Click JOINT_1
a
c
b
14
Verify Your Model
a.
b.
In the lower right corner of the modeling window, right-click on the Information icon.
Click on the Verification icon.
a
b
c.
d.
The Info Window appears
After seeing that the model has verified successfully,
click on the Close button
d
c
Note: The model verification step is one way to find errors in the model definition. ADAMS checks for error
conditions such as misaligned joints, unconstrained parts, or massless parts in dynamic systems, and alerts you to
other possible problems in the model.
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Run a Simulation
How to simulate the model:
a.
Click on the Simulation tool in the Toolbox.
b.
Select Duration from pull down menu
c.
Enter 2
d.
Select Step Size from pull down menu
e.
Enter 0.01
f.
Click on the Play button.
a
If everything has been done correctly the bar should complete one
revolution.
d
c
b
b
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Save Database
a.
Save your database by Click File Save Database, and select no for a backup copy
a
To export a .cmd file
b.
Click File
Export
c.
Select ADAMS/View Command
File from File Type pull down menu
d.
Enter a File name
e.
Click OK
c
d
b
e
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Create Part 2
a.
Create another extruded triangle, with thickness = 0.2, using points:
(0.04, 0.0, 0.0) (0.3, 0.0, 0.0) (0.25, -0.15, 0.0)
b.
Modify Extrusion points using link3.txt
c.
Rename the part to link_3
d.
Create Marker at Point (0.32,0.0,0.0), rename it B3
e.
Create a revolute joint between link_2 and link_3
d
e
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Revolve Part
a.
Click anywhere on Link 3. Notice that everything is highlighted and there is a green handle at the
end of the y axis on the coordinate located at A2.
b.
Click on this handle and drag left. This causes Link 3 to rotate about that point. Let Link 3 in this
position for now so it is out of the way.
b
a
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Verify and Simulate
a.
Verify you model
b.
Run a simulation: Duration = 2.0, Step Size = 0.01
b
a
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Create Marker
a.
Create Marker on the ground at point (0.26, -0.04, 0.0)
b.
Rename it O4
a
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Create Part 4
a.
Draw another triangle with the Extrusion tool this time with the first point at O4. Repeat the previous steps and read
in Link4.txt to correct the shape.
b.
Create a marker on link 4 at position (0.66, -4.0E-002, 0.0), rename it B4
c.
Add a Revolute Joint between link 4 and Ground, at O4.
b
c
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Create Joint between Part 3 and 4
a.
Rotate link_4 so that points B3 and B4 are close
b.
Click the revolute joint tool
c.
Select 2 Bod-2 Loc from Construction pull down menu
d.
Click link_4 link_3 (point) B4 (point) B3
d
b
a
c
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Save Assembled Model
a.
To join these location click Simulate Interactive Controls
b.
Click
c.
Ignore and Close the warning that comes up. The part is now joined
d.
Click
e.
Enter .Webcutter_Asm in New Model text field, Click OK
f.
Click play to run the simulation.
which performs initial conditions solution.
a
f
e
b
d
Note: The warning is stating that the two reference points of the revolute joint are not the same and need to be the
same for the part to run. ADAMS will move the two links so that the points will coincide before running the
simulation.
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Modify Material Properties
a.
Right-Click link 2, Select Part: link_2 Modify
b.
Enter .Webcutter_Asm.Al6063 in Material Type text field
c.
Click OK
d.
Repeat this step for link_3 and link_4.
a
b
c
Note: If you choose the option of just entering density, the Links will have significant deformation during the run.
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Model
This is what your screen should look like when
your model is complete.
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Export Data to Excel
a.
Click File Export Table.
b.
Enter Webcutter in File Name text field
c.
Select plot_1 (or whichever plot you are trying to export) in Plot text field
d.
Select spreadsheet from Format pull down menu
e.
Click OK
f.
Rename file from Webcutter.tab to Webcutter.xls
a
b
c
d
e
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Generate the following
a.
Measure the motor torque at the joint where the motion is applied (use z component)
b.
Measure bearing forces in the joints attached to ground
c.
Measure angular velocity and angular acceleration of all the links (z component)
d.
Modify the applied motion to be a step function
a.
The initial value (at t = 0) of the link rotation angle is 0 degrees
b.
The final value (at t = 1) of the link rotation angle is 720 degrees
c.
Run a simulation for 2 seconds and comment on the motion of the mechanism
e.
Include all your plots in a word document
f.
Name the model and the word document using “first name_last name” format
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