Week 2 Bevel Gear Challenge
Grid Dependency test:
- A smoother mesh provides smoother and more accurate results. The finer the mesh gets , the easier it gets in visualizing the contours. Mesh refinement increases the closeness to the true value.
- Mesh refinement may increases the total number of nodes and elements in the mesh which actually increases the computaional time.
- Therefore, it is necessay to find a suitable mesh size so that further refinement does not change the results significantly.
- In a Grid Dependency test, the analysis is completed for different mesh sizes starting from a higher values to lower values for each element size such that after a particular element size, further refinement does not change the final results.
Objective: To perform a grid dependency test for the bevel gear simulation for mesh sizes of 6,5 and 4 mm and to compare the results obtained of total deformation, Von-Mises Stress and Equivalent elastic strain for the 3 cases.
Materials: Structural steel is used for all the cases.
| Material | Youngs Modulus(GPa) | Poission ratio | Yield Strength(MPa) | ultimate Strength(MPa) |
| Structural Steel | 200 | 0.3 | 250 | 460 |
Model: (common for 3 cases)
Contact Sets:
1. Between the gears a frictional contact is setup with a frictioal coefficient of 0.2.
2. Two revolute joints (body-ground) is applied to the small and big gear.
Mesh:
| Mesh Size | Nodes | Elements |
| Case 1: 4mm | 22015 | 11679 |
| Case 2: 5mm | 20982 | 11095 |
| Case 3: 6mm | 20300 | 10721 |
Analysis Settings:
Joints:
1. Revolute: Ground to big gear . Rotation along Z-axis.
2. Moment: Ground to small gear . 100N-mm.
Results:
Case 1: 4mm
Total deformation:
Von-Mises Stress:
Equivalent Elastic strain:
Case 2: 5 mm
Total Deformation:
Von-Mises Stress:
Equivalent Elastic Strain:
Case 3: 6mm
Total Deformation:
Von-Mises Stress:
Equivalent Elastic Strain:
| Mesh size | Total Deformation(mm) | Von-Mises Stress(MPa) | Equivalent elastic strain |
| Case 1: 4mm | 47.862 | 3.3414 | 1.776e-5 |
| Case 2: 5mm | 47.872 | 3.2906 | 1.761e-5 |
| Case 3: 6mm | 47.872 | 2.5701 | 1.6533e-5 |
From the above table we can conclude that as the mesh is refined, a convergence towards the true value can be seen. The mesh can be further refined to get more accurate value which cannot be done in this case due to the limit of Student version.