Bevel Gear Challenge

1. GRID DEPENDENCY TEST -

Grid or Mesh generation is the basic step in any simulation. In practice of finite-element stress analysis, the engineer first needs to know if key stresses are converging, and second if they have converged to a reasonable level of accuracy. In order to achieve results that are reliable when using the finite element method, it must be ensured that an acceptable mesh is used with respect to the shape and size of the elements. Mesh quality and mesh density values are directly linked with the solution accuracy.

So Grid/Mesh Dependency test also know as mesh convergence test is the study of Variation of results like stress, with the variation of mesh size. This is to check the dependency of result on mesh size. As the mesh gets finer and finer the results become real and accurate at the cost of computational cost. Thus through grid dependency study we achieve a reasonable accuracy in the results without compromising with computational time. The results are generally kept in the range of 3-5% variation as acceptable.

The difference between the stress component and stress considering the discretization in local area of high stress must be less than 5%.

OBJECTIVE - To Perform a grid dependency test for the Bevel gear simulation for mesh sizes of 6,5 and 4 mm and evaluate the different results for Von-Mises Stresses, Deformations and Deformations.

GEOMETRY - The geometry used is shown below. The mating Bevel Gears Assembly is used for analysis provided by the Problem.

Material Properties :

Pre Processing :

1. Contacts - The Small Gear and Large Gear mating faces are given Frictional Contact Property with mating surfaces having Augmented Lagrange Formulation. Frictional Coefficient is \"Zero\".

The interface treatment is given as Adjust to Touch.

Joint Type - Both the gears are given Ground to body joint condition.

Boundary Conditions : Revolute joint on small gear and big gears is given rotation of 120° with increment of 20° in 6 steps on smaller gear and with 100 N-mm Moement of smaller end.

The Analysis Settings are given

Initial Time Step - 0.5 sec

Incremental Time Step - 0.2 sec

maximum Time Step - 1 sec

Roatation Smaller Gear-

Moment (Larger gear)-

Mesh - 6 mm Size.

The body is firstly meshed with 6mm size. The other two iterations are run using 5mm and 4 mm mesh size respectively.

RESULTS -

1. Max Von Mises Stress Plots

6mm -

5mm

4mm

2. Max Deformation Plots

6mm

5mm

4mm

3. Max Equivalent Elastic Strain

6mm

5mm

4mm

Results Comaprison :

Mesh Size (mm)	Von Mises Stress (Mpa)	% Change	Deformation	% Change
6	2.789		47.87
5	3.349	20.078881	47.87	0
4	4.678	9.683488	47.87	0

As visible from the above Von Mises Stress Variation The Stress % change goes on decreasing with decrease in mesh size. Thus on refining the mesh we are reaching more accurate solution.