Week 1 Spur Gear Challenge
Stress Intensity: It is used in fracture mechanics to predict the stress state near the tip of a crack or notch caused by a remote load or residual stresses.
Its value (k) depends on the magnitude of load, location of the crack and goemetry
Objective: To find out the total deformation, equivalent stress and stress intensity of spur gears using different materials like Cast Iron, Cast steel and Cast Broze
Setting up the analysis: Once after opening the geometry in the ANSYS mechanical, we need to define the contacts by selecting the surface areas of teeths of both the spur gears. Type of contact selected is frictional and the algorithm used for contacts is Augumented Lagrangian
Mesh: A mesh size of 3mm is used for the analysis
Figure 1
Boundary conditions: We select 2 joints of 2 gears while one being in roration and the other being moment. We solve by taking time steps. Total of 6 time steps are taken and for rotation, each time step 30 degrees is given. Moment of 10 Nm is the fixed moment for all time steps.
Case 1: Cast Iron
Total Deformation
Figure 2
Equivalent stress
Figure 3
Stress Intensity
Figure 4
Case 2: Cast Steel
Total Deformation
Figure 5
Equivalent stress
Figure 6
Stress Intensity
Figure 7
Case 3: Cast Bronze
Total deformation
Figure 8
Equivalent stress
Figure 9
Stress Intensity
Figure 10
Results
The locations of possible fractures are mentioned with a Max probe in the given figures, that is the place where the fracture is likely to happen. The results of all cases are tabulated below
| Case | Material | Total Deformation(mm) | Equivalent stress(MPa) | Stress Intensity(MPa) |
| 1 | Cast Iron | 30 | 317 | 366 |
| 2 | Cast Steel | 30 | 358 | 413 |
| 3 | Cast Bronze | 30 | 281 | 299 |
Cnclusion: From the above observations we found out the values of stress and stress intensity and got to know that Cast steel has the higher values and Cast Bonze has the lower values. So in comparison with the above materials, it is safe to assume that using Cast Bronze is the better option due to its low stress and Stress intensity values.