Week 9 Machining with Planer Challenge
OBJECTIVE
To carry out an explicit dynamics analysis on a given model that involves a planer carrying out machining on a workpiece. Two cases differentiated by planer speed are to be carried out and outputs compared. The outputs to be requested are equivalent stress, total deformation and the temperatures generated in the workpiece.
MODEL IMAGE
PROCEDURE
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 workpiece.
The cutting tool is also assigned a stiffness behaviour of 'rigid' since no analysis would be carried out on it.
3. Then we can move to Connections > Contacts and delete all the existing contacts. We can leave body contacts as they are.
4. Moving on to meshing, we can assign a tetra mesh to the planer. A tetra mesh is usually applied to more complex geometries. We can introduce tetra mesh by right-clicking 'mesh' > insert > method. The whole cutting tool (planer) is to be selected for this and the method should be 'tetrahedrons'.
We can then assign a mesh sizing on the workpiece. To do so, we need to right-click mesh > insert > sizing. We then need to select the short edges of the workpiece (four of them) with the help of the edge selector tool. The type of sizing should be 'number of divisions' and we can give it a number of 10.
5. Moving on to the analysis settings, we shall be entering an end time of 7.5e-4 ms as shown
6. Next, we need to right-click Explicit Dynamics > Insert > Velocity. We need to select the entire planer body for this. Then, we need to enter tabular data for the direction of velocity application, which is the x coordinate in this case. The requirement was 20000mm/s (case 1) which will be the value of the first (and only) step as shown. After this case is simulated, and analysis carried out, we will need to save the file and come back here to change the velocity to 15000mm/s and repeat the process.
Also, the other components are constrained as shown.
Then, we can assign the fixed support on one of the workpiece surfaces (via right-clicking Explicit Dynamics > insert > fixed support).
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.
Again, this analysis needs to be run again a second time after saving the case 1 file and changing the velocity.
OUTPUTS
CASE 1 - CUTTING VELOCITY - 20000 mm/s
STRESS
Maximum & minimum stress
TOTAL DEFORMATION
Maximum & minimum deformation
TEMPERATURE
Maximum & minimum temperature
CASE 2 - CUTTING VELOCITY - 15000 mm/s
STRESS
Maximum & minimum stress
TOTAL DEFORMATION
Maximum & minimum deformation
TEMPERATURE
Maximum & minimum temperature
OBSERVATIONS
Looking at the stress values, we can see that case 1 with higher planer velocity has lower stresses generated in the workpiece. In case 2, stress values are higher, probably due to impedance from the workpiece due to the lower velocity. But, in the case of the other outputs, case 1 values are higher. These values are affected by the kinetic energy generated. The higher energy is due to the higher velocity and this results in the higher deformation as well as temperature. Friction and velocity have no relation and a velocity increase does not change this frictional force, but it does increase other resulting factors, such as heat, in the system. This explains the increase in temperaure.
RESULT
The explicit dynamic analysis was carried out on the given machining model involving a planer. Two cases of differing planer velocities were carried out and their outputs were generated and compared.