1. WORKSHOP 2 SOLID-TO-SOLID CONTACT

3. Workshop Objectives Software Version Required Files
Learn to handle contact bodies with different mesh densities.
Software Version
MD Nastran 2011
Patran 2011
Required Files
search_order_start.ses

4. Problem Statement
To investigate how to conduct a contact analysis with two bodies that have different mesh densities, this problem will include a mounting bracket that has a coarse mesh and a loading block that is more finely meshed. The mounting bracket has a fixed boundary condition of 0 on its left face. The loading block has a force on its right face pushing it a total displacement of .003 inches into the mounting bracket.
Mounting bracket
Loading block
Fixed BC
Displacement BC

5. Suggested Steps Create a new database.
Build the starting model by running the session file, search_order_start.ses.
Review the load and constraints on the model.
Define two deformable contact bodies.
Set up a linear static analysis
Request contact results and run the analysis.
Review the Nastran input file.
Attach the Master result file.
Plot deformation and von Mises stress results.
Set deformation scale to true scale.
Make a Marker plot of Contact Status.
Plot Normal Contact Force as a vector plot on both bodies.
Display a Fringe Plot of Contact Status on both bodies.
Display a Fringe Plot of Normal Contact Stress on both bodies.

6. Step 1. Create New Database
Create a new database:
Pull down File > New.
Enter contact_search_order as the file name.
Click OK.
For New Model Preference, accept all defaults by clicking OK. d

7. Step 2. Build Starting Model by Running a Session Filec
Build a starting model by running a session file:
Pull down File > Session > Play…
Select search_order_start.ses
Click Apply to play the session file. a

8. Step 3. Review the Model a b c Review the model:
Click Smooth Shaded in the Display group.
Review boundary conditions: The left solid block is fixed at one face.
Review loading: An enforced displacement of is applied to the right block to push it into the left block. b c

9. Step 4. Define Two Deformable Contact Bodies
Create contact body definition for the left solid block:
Under the Load/BCs tab, click Deformable in the Contact Bodies group.
Enter mounting_bracket for the New Set Name.
Click Select Application Region.
Pick the solid with the coarser mesh.
Click Add.
Click OK.
Click Apply. d e f d b c g

10. Step 4. Define Two Deformable Contact Bodies
Create contact body definition for the right solid block:
Enter loading_block for the New Set Name.
Click Select Application Region.
Pick the solid with the finer mesh.
Click Add.
Click OK.
Click Apply. c d e a c b f

11. Step 5. Set Solution Type to SOL 101a
Set up a Linear Static analysis:
Under the Analysis tab, click Entire Model in the Analyze group.
Click Solution Type….
Click Solution Parameters.
Click Results Output Format.
Check MASTER/DBALL and uncheck XDB.
Click OK. c b e d h f g

12. Step 6. Request Contact Results and Run the Analysis
Request contact results output:
Click Subcases…
Click on Default under Available Subcases.
Click Output Requests.
Select Contact Results.
Click OK.
Click Apply.
Click Cancel.
To run the analysis: b d c f g e

13. Step 7. Review Nastran Input File
Review the Nastran input file:
In the training directory locate and open the file contact_search_order.bdf with any text editor.
Note the Case Control entry BCONTACT = ALLBODY indicating that all contact bodies can potentially contact each other. Note also that no contact table (BCTABLE) is present. b a

14. Step 8. Attach Master Result Fileb
Attach the Master result file:
Under the Analysis tab, click Master/DBALL in the Access Results group.
Select contact_search_order under Available Jobs.
Click Apply c

15. Step 9. Plot Deformation and Stress Results
Plot deformation and Von Mises stress:
Under the Results tab click Fringe/Deformation in the Quick Plot group.
Select Stress Tensor for Fringe Result.
Select Displacements, Translational for Deformation Result.
Click Reset Graphics to clear the shading.
Click Apply. b c e

16. Step 10. Set the Deformation Scale to True Scale
Set deformation scale to true scale to accurately show the contact between the bodies:
Click the Deform Attributes icon
Select True Scale.
Click Apply. a b c

17. Step 11. Make Marker Plot of Contact Status
Create a marker plot of Contact Status on the mounting bracket.
View just the mounting bracket (on left) by posting only the mounting_bracket group. (Not shown)
Pull down Create > Marker > Scalar.
Select Contact Status for the Scalar Result.
Click the Display Attributes icon.
Pull down Scalar Style, pick the Solid Sphere.
Set Scale Factor to .03
Click Apply.
The solid sphere markers appear on the mounting bracket as shown.
Contact Status
Marker Plots b d h j c
Create a marker plot of Contact Status on the loading block:
View just the loading block (on right) by posting the loading_block group. (not shown)
When the block is displayed it should have the solid sphere markers as shown above. f e g

18. Step 12. Plot Normal Contact Force
Plot Normal Contact Force as a vector plot on both bodies.
Display a normal force vector plot on the mounting bracket:
View just the mounting bracket by posting the group mounting_bracket. (not shown)
Pull down Vector for Method
For the Fringe Result select Contact Force, Normal.
Pull down Resultant for Show As.
Click Apply.
The normal force vectors will appear on the mounting bracket as shown.
Display normal force vectors on the loading block:
View just the loading block by posting the group loading_block. (not shown)
The normal force vectors are displayed on the loading block. b
Contact Normal Force
(marker plot) f h c d e

19. Step 13. Display a Fringe Plot of Contact Status
Display a fringe plot of Contact Status on the mounting bracket:
View just the mounting bracket by posting the group Mounting_bracket
Pull down Object to Fringe.
For the Fringe Result select Contact Status.
Click Apply.
The fringe plot will appear on the mounting bracket as shown.
Display a fringe plot on the loading block:
View just the loading block by posting the group Loading_block.
When the block appears it will be displayed with the fringe plot. b
Contact Status
(fringe plot) g e c d

20. Step 14. Display a Fringe Plot of Normal Contact Stress
Display a fringe plot of Normal Contact Stress on the mounting bracket:
View just the mounting bracket by posting the group mounting_bracket
For the Fringe Result select Contact Stress, Normal.
Click Apply.
The normal stress fringe plot will appear on the mounting bracket as shown.
Display a fringe plot of Normal Contact Stress on the loading block:
View just the loading block by posting the group loading_block.
When the block appears it will be displayed with the fringe plot.
Contact Normal Stress
(fringe plot) d f b c