137 - understanding interfaces

8/13/2019 137 - Understanding Interfaces

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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.

137 - understanding interfaces

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