Week 2 Bevel Gear Challenge

Objective :

The objective of this challenge can be stated as below:

1. Elaborate on grid dependency test and perform a test.

2. To perform the simulation of Bevel gear and determine Von-mises stress, Equivalent elastic strain and Total Deformation using mesh sizes of 6,5 and 4 mm and present the findings.

Solution 1:

Grid Dependency Test

Basic theme of FEA is to make calculations only at limited number of points and then interpolate that result for the entire domain.The FEM reduces the degrees of freedom from infinite to finite with the help of discretization that is meshing via nodes and elements. The output result for the coarse and fine mesh vary fronm one another, so a grid dependency test is needed to reach an optimum result.

With reference to the grid dependenct test, in order to get the most accurate solution the meshing is varied from coarse to fine and the output result is checked for each mesh When varying the mesh does not affect the result much then we can stop and select that minimum mesh size for our final solution output.

Solution 2: 

Geometry Update:

The gear geometry has been updated in the spaceclaim and some central part of the gears has been reduced as it is not the point of interest in this simulation.

Contact:

The Contact has been defined as frictional between the set of gears and only the required faces which gets engaged are defined as contact and target faces respectively as shown below.

These are having frictional contact with symmetric behaviour. The formulation is defined as Augmented Lagranges whereas the interface treatment is set to adjust to touch.

 Joints:

Revolute Joints has been set up between the gears with respect to ground.

Meshing:

For the meshing requirement, the gear tooth face has been given a finer mesh which is 1.75 mm and other regions of the gear which are not the point of interest are provided with coarse mesh.

Also, for the grid dependency test parametric set has been created and the mesh sizes are given as input parameters.

Analysis Settings:

The analysis has been set up in 6 steps with specifying the initial, minimum and maximum time step and the time stepping is automatically controlled. Also, the large deflection is kept on.

Boundary Condition:

The boundary conditions has been applied to the two revolute joints as Joint load in such a manner that the pinion or small gear is given an angular rotation in the increment of 20 degrees while the big gear is provided with a constant moment of 100 N-mm.

Below we can see the results using the general area mesh size as 4 mm while tooth face mesh size as 1.75 mm.

Equivalent Stress:

Equivalent Strain:

Total Deformation:

 Parametric Study Related:

Variation of parameters with change in mesh size :

Conclusion:

1.  As the mesh was made finer, the number of nodes and elements increases and this resulted in increase in computation time and accuracy.

2. Also, with refining the mesh the output result started converging to closer values.