ANSYS Mechanical Advanced Contact & Fasteners

Transcription

1 Workshop 2C Contact with Friction Release ANSYS Mechanical Advanced Contact & Fasteners 1

2 Workshop 2C: Contact with Friction Goal Create contact pairs between three parts (piston, cylinder and seal). Run 2 load step analysis to simulate assembly of the three parts together. Post Process force along axis to assembly parts. Piston Model Description 2D Axisymmetric Piston is constrained from movement. Cylinder is displaced to simulate assembly Materials: Steel for Piston and Cylinder Elastomer for O Ring 1 st load reconciles interference between piston and inside diameter of O ring 2 nd load step slides cylinder onto piston O ring subassembly. O-ring Cylinder 2

3 Steps to Follow: Workshop 2C: Contact with Friction Restore Archive browse for file W2c_friction.wbpz Save as File name: WS2c friction Save as type: Workbench Project Files (*.wbpj) 3

4 The project Schematic should look like the picture to the right. Highlight the Engineering Data Cell and open by clicking on the Right Mouse Button (RMB)=>Edit to verify the predefined material properties elastomer and Structural Steel Verify that the units are in Metric(Tonne,mm, ) system. If not, fix this by clicking on Utility Menu=>Units=>Metric(Tonne, mm, ) 4

5 Return to the project schematic page Double click (or RMB=>Edit ) on the Model Cell to open a Mechanical Session 5

6 Once inside the Mechanical application, verify the working unit system Unit > Metric (mm,kg,n,s,mv,ma) The piston cylinder assembly is already set up as a 2D axisymmetric model with the necessary boundary conditions and loads. It remains to define the contact pairs between the parts, set up the solution control analysis settings, run the solution and post process the results. Expand each folder in the project tree to become familiar with the model and to confirm material assignments for each part, boundary conditions, loads and Analysis Settings. 6

7 Note: Auto contact detection did not create adequate contact relationships for this model. There is only one bonded contact pair created by default and it is insufficient for representing the assembly. 7

8 Redefine the O-ring To Piston contact region as follows: Target definition should include the three surfaces on the piston side as shown. Contact should be on the o Ring side (2 edges) Change Type to Frictional Friction Coefficient = 0.2 target Switch behavior to Asymmetric Normal Stiffness = 0.1 Updated stiffness each iteration Pinball Radius = 2mm 8

9 Insert an additional manual contact region between O ring and Cylinder wall by highlighting Contact branch and RMB>Insert>Manual Contact. Defined this new region with specifications below. Contact Target 9

10 Confirm the Analysis Settings Large deflection is turned On There are two load steps with different Auto Time Stepping specifications 10

11 Confirm the displacement load of 10mm is applied to the cylinder at load step 2. 11

12 Execute the solve. After many iterations and a few bisections, the solution converges. 12

13 Review the Total Deformation results. Change the contour bar to clarify the deformation of the O ring geometry Animate the result 13

14 Highlight Solution Branch and RMB>Insert>Contact Tool Insert and post process contact status, pressure, frictional stress and penetration After reviewing results, Re Save this Project for use later in Workshop 3B 14