Performing Grid dependency test on Bevel Gear setup
Objective
To perform Grid dependency test for the Bevel gear simulation for mesh sizes of 6,5 and 4 mm
Grid dependency test is and its use.
Grid dependency is also Known as Mesh Convergence in FEA.
Coarse meshes can yield inaccurate results in analyses using implicit or explicit methods.
The numerical solution provided by the model will tend toward a unique value as you increase the mesh density. The computer resources required to run your simulation also increase as the mesh is refined.
The mesh is said to be converged when further mesh refinement produces a negligible change in the solution.
It is always good practice to perform a mesh convergence study, where same problem is simulated with a finer mesh and compare the results. One can ensure that the model is producing a mathematically accurate solution if the two meshes give essentially the same result.
Mesh convergence is an important consideration in FEA.
Importing the model
The CAD model is imported and viewed in spaceclaim and making sure there are no errors in the geometry.
Simulation Setup
Contact Definition
The material is chosen as structural steel. The auto generated contacts are deleted and manually the gear faces which will come in contact area are alone chosen as contact surfaces.
The contact properties are
Type - frictional contact
Formulation - Augumented lagrange
Interface treatment - Adjust to touch
Joint creation
Two body-ground revolute joint is created for the two gears.
Mesh generation
Face sizing is made for the gear teeth faces which come under contact area.
The face sizing is done at an element size of 1.75 mm.
Then the model is meshed with three different mesh with element sizes 6mm , 5mm , 4mm
Analysis settings
Larger gear is applied with a moment value of 100 Nmm
Smaller gear is given rotations in 6 steps each step has increment of 20 degree. The angle of rotation is 0-120 degree
Results
The model is solved and following results are generated Total deformation, Equivalent strain and Equivalent stress
The force-convergence plot is viewed and it can be concluded that the model results have converged without any convergence issues
Case (1) - 4mm
Total deformation
Equivalent strain
Equivalent stress
Case (2) - 5mm
Total deformation
Equivalent strain
Equivalent stress
Case (3) - 6mm
Total deformation
Equivalent strain
Equivalent stress
Comparing the results of three different meshed models
Total deformation and maximum equivalent strain is almost equal for all the 3 meshed models.
Even if the mesh size is decreased from 6mm to 4mm, there is only marginal difference in stress vales
In conclusion, it can be stated that at mesh size 6mm itself results are accurate and when we decrease the mesh size to 5mm or even 4mm there is no significant improvement in simulation results.
Thus, grid dependency test is performed on a Bevel gear setup.
Google drive link for the ansys file
https://drive.google.com/file/d/1ExcY2uNOZfPP1a3ZSrdBQAFFTrb3QMcP/view?usp=sharing