Cylinder on a Plane in ANSYS Workbench Go to the web page and download the “Cylinder_on_plane.igs” file for the geometry. Load the geometry file into ANSYS. Notice that o geometry is in the x‐y plane (necessary for plane strain) o cylinder is split into top and bottom half to make analyzing results easier o 10 diameters is a big domain Close DesignModeler Switch to a 2D Analysis Type (Properties of Geometry in Project Schematic window) Open Mechanical o In “Details of Geometry” switch from Plane Stress to Plane Strain Check the contact region (under Connections‐> Contact Region). Leave it Bonded for now. Mesh o Generate a default mesh. Notice that it’s not nearly good enough. Almost the entire cylinder will fit into the first element in the plane. o Apply an Edge Sizing to the top edge of the rectangular plane. Select a bias type that looks like Now use the help on “Bias Factor” to figure out how to make the smallest element edge on that line 1/10th as big as the largest element edge o Now apply an Edge Sizing to the left edge of the rectangular plane and make the elements get gradually larger as we move away from the cylinder. o At this point, you probably have a decent (although coarse) mesh. Apply appropriate boundary conditions to the centerline of the domain and the bottom of the “semi‐infinite plane” Apply a 0.1m displacement on the top vertex of the cylinder. Run the analysis. Look at the results for normal stress in the y direction. o Zoom in on the contact surface. Use true scale (1.0). How does the interface look? Since that was just “Bonded”, we shouldn’t have expected much anyway. Change to “Frictionless” and run again. How does the interface look now? Turn on large deflections and run again. How does the interface look now? Go back and change the displacement of the vertex so that it is 10 times smaller than before (0.01m). Solve. o How does the interface look now? o Insert a second stress result which is the normal stress in the y direction just on the two surfaces that are contacting. How does the interface look now? o Insert a “Contact Tool” and look at a few of the results, such as “status”, “penetration”, “gap” Go back and change the displacement of the vertex to 1/100th of where we began: 0.001m. Solve. Inspect the solution again. It seems like we might be getting somewhere. We may not be able to do much better with this mesh. We will see if we can get a solution that compares roughly with the analytical solution from this mesh. o Change the vertex displacement back to 0.01m. o In the Analysis Settings, change “Auto Time Stepping” to “Off”. Change “Define By” to “Substeps”. Change “Number of Substeps” to 10. This should make each substep just 0.001m, which seemed to be working. o Inspect the results. On mine, it seemed as though we have managed to get about half an element of the cylinder to contact reasonably well. What is the current value of “b”? o
Check the reaction force at the cylinder top vertex to check the applied force. Is this the applied force that you would expect for this “b”? (Be careful here—there’s some subtle things occurring.) Try to get your solution for stress and the applied force to match up (very approximately) with your hand calculation. Stick with this mesh, even though it is not very good, because otherwise it will take too long to run. For the homework next week I will have you work on a good mesh.