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AnalyzingAssembliesIIUnderstandingInterfacesLecture
UnderstandingInterfaces.mp3
Understanding Interfaces
Interfaces define how parts will be connected in an Assembly.
Interfaces available
Bonded Free Contact
Assigning the Default Interface
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Coupler Assembly
Coupler Assembly with Model Connectivity highlighting.LectureNotes
Understanding Interfaces
In previous releases of Pro/ENGINEER, Mechanica would assume all assemblycomponents mated together or with coincident surfaces should be merged to function
as a single body. Users now have the ability to change the default behavior. TheDefault Interface between assembly components can be set to:
Bonded: All components that are mated together or with coincident surfaces willbe merged. Users who want specific surfaces to remain free of each other or toendure contact forces can assign a free or contact interface respectively.
Free: All Components are free as individual bodies. Mechanica will not preventinterpenetration between components except along surfaces that have beenassigned a contact or bonded interface.
Contact: Mechanica will create contact regions along all surfaces that meet theseparation gap and angle criteria. The surfaces will not be merged, but
interpenetration will be prevented and contact forces calculated if the user runsa contact analysis. Surfaces that should be merged should have a bondedinterface assigned.
Best Practices
Determining the default interface more appropriate for your model depends largely on
how much time you want to spend assigning interfaces. For instance, if most
components in the model are bonded together, and only one pair of components have
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contact between them, then it would be prudent to set the default to bonded and
assign contact interfaces where needed. Conversely, if most of the components in the
model should have contact interfaces between components, then the default should be
set to contact and then bonded interfaces should be assigned where needed.
UnderstandingInterfacesDemonstrationUnderstandingInterfaces_demo.mp4
UnderstandingInterfacesProcedureProcedure: Using Interfaces in Assemblies
ScenarioIn this exercise, you will change the default Assembly Connectivity and view connected
surfaces.
Interfaces coupler_asm.asm
Task 1.Open the Mechanica application and change the default assemblyconnectivity.
1. Click Applications > Mechanica.
2. From the main menu, click Edit > Mechanica Model Setup....
3. Examine the current settings.
Note the default setting of Bonded.
4. Click OKto close the dialog box.
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5. From the main menu, click AutoGEM > Review Geometry.
6. Click the dark grey color swatch next to the Bonded Interfacescheck box. Set the
color to R = 0, G = 255, B = 0 as shown.
7. Click Closeto set the color and close the Color Editor dialog box.
8. The Simulation Geometry dialog box should appear as shown. Click Apply.
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9. Examine the resulting display of the model.
Note all of the surfaces in green. These are surfaces that have defaulted to
the bonded connection.
Note that there are no green surfaces between BALL.PRT or SLEEVE_C.PRT
and the rest of the model. This is because they were assembled with gaps
and do not have coincident surfaces with other assembly components.
10. From the main menu, click Edit > Mechanica Model Setup...again. This time,select Contactfrom the Default Interface drop-down menu.
11. Type .1in the Separation Distance field. Verify that the Angle field is set to 5and
click OK.
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12. From the main menu, click AutoGEM > Review Geometry > Apply.
Note the surfaces that are less than the specified 0.1 inches from each other
now have the default Contact Interface applied as shown by the yellow color.
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13. Return to the Standard Pro/ENGINEER mode by clicking Applications >
Standard.
14. Click Save from the main toolbar and click OKto save the model.
15. Click File > Close Windowfrom the main menu.
16. Click File > Erase > Not Displayed > OKto erase the model from memory.
This completes the procedure.
UnderstandingInterfacesExerciseExercise: Changing the Default Assembly Interface
Objectives
After successfully completing this exercise, you will be able to:
Change the default assembly interface. Add bonded interfaces to the model where needed. Make use of explode states.
ScenarioYou may encounter scenarios in which contact interfaces need to be assigned between a
number of components, and the surfaces or components in contact are not always clear.
Assembles created for practical applications can have patterned components, parts
sandwiched between each other, and other positional difficulties that make it difficult forthe engineer to determine what may come into contact or make it difficult to select the
appropriate surfaces.
In this exercise, you will learn about a number of options available that make dealing withcomplex assemblies and contact problems significantly easier. This exercise is strongly
recommended for users who expect to work with complex assemblies that may contain
several intertwined parts.
ChgDefAssemInterface coupler_asm.asm
Task 1.Open the Mechanica application, access an exploded state of the assembly,and examine the current simulation geometry.
Note the different components in the assembly. The inner most component
is SLEEVE_A, and SLEEVE_B is sandwiched between SLEEVE_A and
SLEEVE_C. A pattern of spheres are assembled to SLEEVE_A and are all
named BALL.PRT. If interfaces needed to be created between these
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components, surface selection would be a tedious task.
1. Click Applications > Mechanica.
2. From the main toolbar, click View Manager and select the Explodetab ifnecessary.
3. Right-click the Mechanica_Explodeview from the list in the Names area of the
dialog box and select Explodeas shown in the figure to the right.
4. From the main menu, click AutoGEM > Review Geometry.
5. Click the dark grey color swatch next to the Bonded Interfacescheck box. Setthe color to R = 0, G = 255, B = 0 as shown.
6. Click Closeto set the color and close the Color Editor dialog box.
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7. The Simulation Geometry dialog box should appear as shown. Click Apply.
8. Examine the resulting display of the model.
Note that the only surfaces bonded to each other are on SLEEVE_A and
SLEEVE_B. SLEEVE_C and the spheres are not bonded to any otherassembly component. Feel free to Spin/Pan/Zoom while the surfaces are
highlighted to get a better view of the surfaces that are bonded.
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Task 2.Change the default interface.
1. Start the process of changing the default interface in the model by clicking Edit >
Mechanica Model Setupfrom the main menu.
2. Select Contactfrom the Default Interface drop-down menu.
3. Verify that the Separation Distance field is set to 0, the units field is set to in, and
the Angle field is set to 5.
4. The dialog box should now appear as shown in the figure. Click OKto finish
changing the Mechanica Model Setup and close the dialog box.
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5. From the main menu, click AutoGEM > Review Geometry > Apply.
Note that the surfaces defined for contact are limited to SLEEVE_A,
SLEEVE_B and only one of the spheres. Contact surfaces were not defined
for all spheres or SLEEVE_C because the gaps that separate them from the
other components is greater than the separation distance of 0that you
specified in the Mechanica Model Setup dialog box in the previous step.
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It is now obvious that too many surfaces have been assigned contact. It is
obvious that the outer surface of SLEEVE_C is not in contact with any other
component, yet it has been assigned a contact interface. It is clear that the
separation distance was set to too large of a value.
10. Click Edit > Mechanica Model Setupfrom the main menu.
11. Type .1in the Separation field as shown in the figure.
12. Click OKto finish editing the Mechanica Model Setup and close the dialog box.
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13. Check connectivity again by clicking AutoGEM > Review Geometry > Apply.
Note that the model now has appropriate contact surfaces.
14. Click Closeto close the Simulation Geometry dialog box.
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Task 3.Define bonded interfaces between surfaces in SLEEVE_A and SLEEVE_B.
With all the components in the model having contact defined between one
another, bonded interfaces can now be defined between surfaces that you
want to merge together. For the purpose of this exercise, part SLEEVE_A
and part SLEEVE_B will be bonded together, while preserving the contact
interfaces already created in this exercise.
1. Click Interface from the Mechanica toolbar.
2. Verify that the Type field is set to Bondedand select Component-Componentfrom the References drop-down menu.
3. Select SLEEVE_A from the model tree as the first reference.
4. Select SLEEVE_B from the model tree as the second reference.
5. The dialog box should appear as shown in the figure. Click OKto complete the
Interface Definition and close the dialog box.
6. Check connectivity again by clicking AutoGEM > Review Geometry > Apply.
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Note that contact is now defined between all components except SLEEVE_A
and SLEEVE_B. If this were done by selecting individual surfaces (as
opposed to changing the Default Interface to Contact) and not using the
exploded view, it would have taken significantly more time.
7. Click Closeto close the Simulation Geometry dialog box.
Task 4.Save the model and erase it from memory.
1. Return to the Standard Pro/ENGINEER mode by clicking Applications > Standard.
2. Click Save from the main toolbar and click OKto save the model.
3. Click File > Close Windowfrom the main menu.
4. Click File > Erase > Not Displayed > OKto erase the model from memory.
This completes the exercise.