1. Snap Fit Workshop Seventeen Introduction to Contact REFERENCE: Training Manual Introduction to Contact (7-69)

2. Workshop Supplement October 15, 2001 Inventory # 001566 W17-2 Purpose Introduce the Contact Wizard for creating contact pairs Goal Create a contact pair utilizing the Contact Wizard, solve the contact analysis, and post-process the results Model Description Snap fit assembly Axisymmetric Applied displacement 17.Introduction to Contact Snap Fit 0.4 inches applied displacement axis of symmetry

3. Workshop Supplement October 15, 2001 Inventory # 001566 W17-3 17.Introduction to Contact …Snap Fit STEPS TO FOLLOW: 1.Start an ANSYS Interactive session in the working directory specified by the instructor using “snap” as the jobname 2.Resume the SNAP database –Utility Menu > File > Resume from Select “snap.db1” [OK] –OR enter the following command: RESUME, snap, db1 NOTE: The snap.db1 database contains the completed geometry, material, and boundary condition definitions for this finite element model.

4. Workshop Supplement October 15, 2001 Inventory # 001566 W17-4 17.Introduction to Contact …Snap Fit Steps 3-7 involve creating a contact pair using the Contact Wizard: 3.Enter the Contact Wizard –Main Menu > Preprocessor > Create > Contact Pair > Contact Wizard 4.Designate the target surface Target Surface: Lines [Pick Target] Select 14 lines as shown: [OK] LINE NUMBERS:

5. Workshop Supplement October 15, 2001 Inventory # 001566 W17-5 17.Introduction to Contact …Snap Fit 5.Designate the contact surface [Next] Contact Surface: Lines [Pick Contact] Select 8 lines as shown: [OK] [Next] LINE NUMBERS:

6. Workshop Supplement October 15, 2001 Inventory # 001566 W17-6 17.Introduction to Contact …Snap Fit 6.Specify optional settings [Optional Settings] Normal penalty stiffness = 0.1 [OK] NOTE: For bending-dominated problems, use FKN = 0.1 as a starting estimate.

7. Workshop Supplement October 15, 2001 Inventory # 001566 W17-7 17.Introduction to Contact …Snap Fit 7.Create the contact pair Coefficient of Friction = 0 [Create] [Finish] NOTE: The log file will contain the commands executed by the Contact Wizard separated by START and END comments.

8. Workshop Supplement October 15, 2001 Inventory # 001566 W17-8 17.Introduction to Contact …Snap Fit 8.Apply 0.4 inches displacement in the -Y direction (axial) –Utility Menu > Plot > Elements –Main Menu > Solution > Apply > Displacement > On Nodes Select node number 19 [OK] UY Displacement value = -0.4 [OK] –OR enter the following commands: /SOLUTION D, 19, UY, -0.4 Pick node number 19

9. Workshop Supplement October 15, 2001 Inventory # 001566 W17-9 17.Introduction to Contact …Snap Fit 9.Specify “Basic” solution control options –Main Menu > Solution > Sol’n Control Select tab: “Basic” Analysis Options = Large Displacement Static Time at end of loadstep = 0.4 Number of substeps = 20 Max no. of substeps = 500 Min no. of substeps = 10 All solution items Write every substep [OK] –OR enter the following commands: NLGEOM, ON TIME, 0.4 NSUBST, 20, 500, 10 OUTRES, ALL, ALL

10. Workshop Supplement October 15, 2001 Inventory # 001566 W17-10 17.Introduction to Contact …Snap Fit 10.Solve the contact analysis –Main Menu > Solution > Current LS [OK] –OR enter the following command: SOLVE 11.Read the results for the last substep –Main Menu > General Postproc > Last Set –OR enter the following commands: /POST1 SET, LAST 12.Plot the contact pressure –Main Menu > General Postproc > Plot Results > Element Solu Contact Pressure PRES [OK] –OR enter the following command: PLESOL, CONT, PRES

11. Workshop Supplement October 15, 2001 Inventory # 001566 W17-11 17.Introduction to Contact …Snap Fit 13.Plot the von Mises stress –Main Menu > General Postproc > Plot Results > Nodal Solu Stress von Mises SEQV [OK] –OR enter the following command: PLNSOL, S, EQV 14.Disable automatic fit mode –Utility Menu > PlotCtrls > View Settings > Automatic Fit Mode Disabled [OK] –OR enter the following command: /USER, 1

12. Workshop Supplement October 15, 2001 Inventory # 001566 W17-12 17.Introduction to Contact …Snap Fit 15.Animate the von Mises stress –Utility Menu > PlotCtrls > Animate > Over Time Use Last Display [OK] –OR enter the following command: ANTIME, 10, 0.5,, 1 16.Enable automatic fit mode –Utility Menu > PlotCtrls > View Settings > Automatic Fit Mode Enabled [OK] –OR enter the following command: /AUTO, 1 NOTE: You need to stop the animation before issuing any other plot commands.

13. Workshop Supplement October 15, 2001 Inventory # 001566 W17-13 17.Introduction to Contact …Snap Fit 17.Define the reaction force variable –Utility Menu > Plot > Elements –Main Menu > TimeHist Postpro > Variable Viewer… Select “snap.rst” file [open] Press Add Data Button Reaction Forces >Structural Forces > Y Component of Force Variable Name: “FORCE”

14. Workshop Supplement October 15, 2001 Inventory # 001566 W17-14 17.Introduction to Contact …Snap Fit 17.Define the reaction force variable (cont’d) Select node number 19 or enter “19” in the ANSYS input window [OK] Select node number 19

15. Workshop Supplement October 15, 2001 Inventory # 001566 W17-15 17.Introduction to Contact …Snap Fit 17.Graph the load vs. Deflection Curve Press the Graph Button

16. Workshop Supplement October 15, 2001 Inventory # 001566 W17-16 17.Introduction to Contact …Snap Fit EXTRA CREDIT: Restart the analysis and increase the vertical deflection to 0.55 inches in the -Y direction Review the results (create von Mises contour and load vs. deflection graph as follows) Why does the response contain both positive and negative reaction forces?