Week 9 Tension and Torsion test challenge
OBJECTIVE
To carry out an explicit dynamics analysis through a tension and torsion test on a given test piece specimen. For the tension test, one end of the specimen is to undergo a displacement of 18mm whereas, for the torsion test, the end is to undergo a displacement of 1200 degrees. The outputs to be requested for each are total deformation, equivalent stress and temperature of the specimen.
MODEL IMAGE
PROCEDURE
TENSION TEST
1. After opening ANSYS Workbench, we are met with the Project Schematic window. Here, we can select the 'Explicit Dynamics' analysis system on the left. Doing so creates a new project. Here, we can rename the project and also input the material. We will need to right-click 'Geometry' and select 'import'. The file provided for this project should be selected.
Now, we can add a material for the analysis. To do that, we need to double-click Engineering Data'. This opens up the list of inserted materials. We can then pick materials we need from the repository listed in the Engineering Data Sources. Going to the 'Explicit Materials' source, we can pick STEEL 1006.
After that, we simply need to click the yellow '+' symbol on the material's corresponding 'add' column to add this specific material to the project. Once we are done, we can simply close the tab.
We can then exit out of the engineering data tab and return to the project schematic window, where we can right-click geometry and select 'edit'. This will bring the model up in the Mechanical interface.
2. In the mechanical interface, in the outline, under geometry, we can rename each of the components. We also need to assign the material to the specimen.
3. Now, we need to create local coordinate systems for the curved surfaces on each end of the specimen separately (as in the screenshot). To do that, we simply need to select the surface and select the 'coordinate system' option in the coordinate systems section of the context toolbar on the top. We repeat this process for the other side as well. Doing so creates them without having to manually adding in the surface in the attribute section.
4. Then, we can work on the mesh. We can introduce tetra mesh by right-clicking 'mesh' > insert > method. The whole body is to be selected for this and the method should be 'tetrahedrons'.
In addition to that, we also need to introduce sizing for either surface for which the local coordinate systems were created. To do so, we need to right-click mesh > insert > sizing. We then need to select the surfaces and the type needs to be 'sphere of influence'. The radius is to be 22mm and the element size would be 3mm. The reference coordinate system would be their respective local coordinate systems that were created.
So that would mean repeating the process for the second surface as well (and therefore two sizing entities).
5. Moving on to the analysis settings, we shall be entering an end time of 1e-3 ms as shown:
We needn't worry about any of the other settings.
6. Next, we need to right-click Explicit Dynamics > Insert > Displacement. We need to pick one of the two surfaces (the surfaces for which mesh sizing was carried out) and the flat surface on the same end. Then, we need to enter tabular data for the direction of displacement, which is the x coordinate in this case. The requirement was 18mm which will be the value of the first (and only) step as shown.
Then, we can assign the fixed support on the opposite side (via right-clicking Explicit Dynamics > insert > fixed support). The corresponding surfaces need to be selected, similar to what was selected for the displacement condition.
7. Now we can generate the outputs. To do this, we can right-click Solution > Insert > Stress > Equivalent (Von-Mises) (for stress) and right-click Solution > Insert > Deformation > Total (for total deformation).
Now, all we need to do is right-click solution again and click 'Evaluate all results'. Once that is done, with 'solution' selected, we can select 'worksheet from the top toolbar and look for the temperature quantity. Right-clicking it, we get the option to generate a user-generated result, which we shall do.
We can then solve this particular result and receive its output as well.
Finally, when the analysis is done, we can view the results by simply clicking each of these solution entities we created, in the Outline menu.
Now, we can close the Mechanical interface to return to the main workbench interface to continue with the torsion test.
TORSION TEST
1. We need to right-click the tension project in the project schematic and duplicate it. We can then rename it as 'torsion test'. Then we can right-click 'model' and click edit to move on to the mechanical interface to set up the torsion test.
2. In the mechanical interface, we can work on the mesh first. We can create a sizing attribute for either surface off the centre as shown, with a mesh size of 1.5mm.
Then, we can introduce a sphere of influence type sizing for the surface in the centre, with a radius of 8mm and a mesh size of 1mm.
3. We can then create a coordinate system for the same centre surface. This time, we will need to create a cylindrical type system. The principal axis may require changing to ensure the y axis denotes the proper direction of torsion (as denoted in the displacement screenshot that will follow).
4. We can then edit the displacement attribute and change the reference coordinate system to the cylindrical coordinate system we just created. Then, we can enter tabular data for the direction of rotation. The only step is given the value of 1200 degrees and the other coordinates are constrained (by simply entering 0mm for.
Now, all we need to do is right-click solution again and click 'Evaluate all results' since the outputs had already been copied from the tension test.
Finally, when the analysis is done, we can view the results by simply clicking each of these solution entities we created, in the Outline menu.
OUTPUTS
TENSION TEST
STRESS
Maximum & minimum stress
TOTAL DEFORMATION
Maximum & minimum deformation
TEMPERATURE
Maximum & minimum temperature
TORSION TEST
STRESS
Maximum & minimum stress
TOTAL DEFORMATION
Maximum & minimum deformation
TEMPERATURE
Maximum & minimum temperature
OBSERVATIONS
From the numbers, we can see that the torsion test has higher values. The testpiece undergoes necking in the tension test and completely fractures in the torsion test due to the shear stress reaching its maximum. This shear in the torsion test also produces higher temperatures due to how shear force works. The friction generated between surfaces acting in opposing directions generates higher temperatures compared to the simple tensile forces in the tensile test.
RESULT
The explicit dynamic analysis was carried out on the given test piece through a standard tensile and torsion test. The required outputs of equivalent stress, total deformation and temperature were generated and it was established that the torsion test produced higher output results.