Workbench-Mechanical Structural Nonlinearities

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Christina Lawrence
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1 Workshop 2B Assembly Contact Workbench-Mechanical Structural Nonlinearities WS2B-1

2 Workshop 2B Assembly Contact Goal: In this workshop our goal is to investigate the behavior of the pipe clamp assembly (Pipe_clamp.x_t) shown here. Specifically we wish to determine the crushing stress and deformation in a copper pipe section when the bolt in the clamp is torqued down. WS2B-2

3 We will assume the material used for the pipe is a copper alloy while all other parts are steel. It is assumed the clamp is torqued to 1000 N when placed in service. We ll assume the coefficient of friction between the clamp and pipe is 0.4. The other contact regions will be treated as either bonded or no separation as shown in the accompanying figures. WS2B-3

From the Toolbox, double click Static Structural to create a new

4 If previous workshop project is still in session, clear it from the project page Utility Menu > File >New 1. From the Toolbox, double click Static Structural to create a new system RMB the geometry cell and Import Geometry and browse to Pipe_Clamp.x_t WS2B-4

5 From the Units drop down menu: Set Project units to Metric (Tonne, mm, s, C, ma, N, mv). Display Values in Project Units is checked (on). WS2B-5

6 3. Double Click the Model cell to open the Mechanical Application Once inside the Mechanical application, set the working unit systems Unit>Metric(mm,kg,N,s,mV,mA) 4. WS2B-6

7 5. Expand the Connections branch and use the shift key to highlight all contact definitions In the details window change the Formulation to Augmented Lagrange. 6. WS2B-7

7. Highlight the first contact branch. This is the definition for the pipe to clamp contact. 7. 8.

8 7. Highlight the first contact branch. This is the definition for the pipe to clamp contact In the detail for the definition change the Type to Frictional. 9. Enter a value for Friction Coefficient of WS2B-8

10. Highlight the second contact branch. This is the definition for the bolt shaft to clamp hole contact. 10. 11.

9 10. Highlight the second contact branch. This is the definition for the bolt shaft to clamp hole contact From the details window change the Type to No Separation. The remaining 2 contact regions will be modeled using the default bonded type of contact. 11. WS2B-9

10 Create a local coordinate system along the pipe s axis. Note, we will use the local coordinate system for post processing later. With the Coordinate system branch highlighted: 12. Select the inside surface of the cylinder. 13. RMB > Insert > Coordinate System WS2B-10

11 14. From the detail for the new coordinate system change Type to Cylindrical. 15. Change the Principal Axis to the Z Direction 16. Defined by Geometry Selection 17. Click to Change on Geometry, then select the inner surface of the pipe and Apply WS2B-11

12 18. In the Details of Analysis Settings Window, define the following: Number of Steps = 2 Large Deflection = On This analysis is run in two load steps. In, Load Step 1, apply the bolt pretension In Load Step 2, lock this pretension and postprocess the working load. WS2B-12

13 19. Select one of the end surfaces of the pipe. 20. Highlight Static Structural Branch RMB > Insert > Fixed Support WS2B-13

14 21. Select the cylindrical face of the bolt part. RMB > Insert > Bolt Pretension 22. In the Detail of Bolt Pretension window enter a Preload value of 1000 for Load Step 1. Using the Timeline, Set load step to 2 and define Pretension as Lock WS2B-14

15 23. Switch to Body select mode. 24. With Solution Branch highlighted, select the pipe part. 25. RMB > Insert > Deformation > Directional WS2B-15

16 26. From the detail for the Directional Deformation change to Coordinate System. 26. Note we allowed the default name Coordinate System to be used when the local system was created. We could easily change the name to a more meaningful one. WS2B-16

17 27. Switch to face select mode. 28. Highlight the outer surface of the pipe. 29. RMB > Insert > Contact Tool 30. RMB Contact Tool in the Contact Tool Branch Insert > Pressure Repeat step 30 inserting contact Frictional Stress Solve 29. WS2B-17

18 The solution for this workshop might take several depending on the available hardware. The use of frictional contact triggers a nonlinear solution requiring equilibrium iterations. The solution progress can be viewed by opening the Solution Information folder. WS2B-18

19 Recall that the solution triggered the use of Weak Spring stabilization. To insure that the weak springs are not the result of rigid body motion, Highlight Solution, RMB > Insert > Probe> Force Reaction and specify in the details window the boundary condition as Weak Springs Verify that the reaction in the weak springs is of the order e-5, a negligible value. WS2B-19

pretension working load equals user defined preload In Details of Bolt

20 Highlight Solution. RMB > Insert > Probe > Bolt Pretension to verify that the bolt pretension working load equals user defined preload In Details of Bolt Pretension, define Boundary as Bolt Pretension (Trivial since there is only one bolt in this model). RMB > Evaulate Results WS2B-20

21 Insert and plotting the Total Deformation for the assembly. This plot is not particularly useful for our goal (investigation of pipe s behavior). The scoped result we placed in the solution branch earlier will be more instructive. WS2B-21

22 Highlight and plot the result Directional Deformation. In this case the result is scoped only to the pipe section. Also, since we employed a local cylindrical system at the pipe axis, the X direction here is displayed in the radial sense. WS2B-22

23 Similarly, the behavior of the contact region can be viewed by highlighting the contact result objects. Again the use of scoped results allows a more intuitive plot of the quantity displayed. WS2B-23

Workshop 3.1 2D Gear and Rack Analysis

Workshop 3.1 2D Gear and Rack Analysis 16.0 Release Introduction to ANSYS Mechanical 1 2015 ANSYS, Inc. February 27, 2015 Assumptions Workshop 3.1 consists of a 2 part assembly representing spur and rack