Week 2 Bevel Gear Challenge

Bevel Gear Simulation.

Objective - 1) To explain about grid dependency test and its uses.

2) To run the simulation with various mesh sizes of 4mm, 5mm & 6mm respectively and note down all the results.

Grid Dependency Test - We all know that how meshing is important in any ansys simulation. Meshing basically defines how well or bad your results are or how good your solution is converged .We may define mesh as either course of fine. Selection of element size always depend on the model in which we are performing. It’s about the time needed for the solver to converge and mesh refinement. Sometimes very coarse mesh may take much less time but the solution won’t be converged and will show errors, So selecting a fine mesh divided the solid model into more number of nodes & elements Therefore this Grid dependency means we have to select the right choice of mesh in which the solution will provide the accurate results and not refining to a much higher level so as to solve the model Converge the solution. In the below attached file we are using 3 mesh sizes of 4mm, 5mm & 6 mm. We will check and evaluate the results and their differences at various sizes.

Case Setup & Execution-

1. Open Static Structural in Workbench, Import Geometry as provided and select Edit to open the model in Space Claim. As in this we are mostly looking for gear teeth and their evaluation on stress strain and deformation, using the circle and pull option in toolbar remove the inner face of the both the pinion and bevel gear. Then update the model and select edit in model. After opening the model rename the parts and select the required material. Here we have proceeded with Static Structural as material. After that click on connections and select ' Based on Definition ' to automatic generate results. After that select 24 faces of big teeth and 16 faces of pinion gear in target and Contact options. Select Type - Frictional, Behaviour-Symmetrical, Formulation - Augmented Lagrange, Interface Treatment - Adjust to touch. In Contacts add two Joints for both of gears and select Body- Ground and revolute Joint, Choose Scope as inner part of gear. Similarly do the same for second gear. Now moving to analysis Setting select the no of steps as 6 as Simulation will work in 6 steps with initial step = 0.1, Minimum step= 5e-2, maximum step = 0.2. As going with much higher step won’t converge the solution and showcase various error with mesh size of 4mm, 5 mm & 6mm. Insert Joint load and select the pinion gear and provide a rotation of 120 deg with 20deg in 6 different steps. With the big gear provide a moment of 100Nmm and look for the rotation of both the gears. Now moving to the final and important step of simulation that is mesh, Select sizing and choose the teeth of the gear as it is the important part of simulation.To get a mesh that will converge the solution we have to choose the teeth of gear with 1.75mm Mesh and other part of gear as 4mm, 5mm & 6mm respectively. Now the solution will converge and we will have no errors solving the same. Now choose Equivalent stress, Deformation and strain as per requirement and Hit Solve.

Solution for Mesh Size of 4 mm: The maximum Equivalent stress generated is 5.4972 Mpa and Equivalent strain is 3.055e-5. Also total deformation is 47.884(max)

Solution for Mesh Size of 5mm: The maximum Equivalent stress generated is 4.4421 Mpa and Equivalent strain is 2.837e-5. Also total deformation is 47.884(max)

Solution for Mesh Size of 6mm: The maximum Equivalent stress generated is 5.5566 Mpa and Equivalent strain is 3.5482e-5. Also total deformation is 47.884(max)

Sr no	Mesh Size	Elements	Nodes	Stress ( Max) Mpa	Strain ( Max)	Deformation (mm)
1	4mm	14983	27882	5.4972	3.055e-5	47.884
2	5mm	14202	26446	4.4424	2.837e-5	47.884
3	6mm	14171	26331	5.5566	3.5482e-5	47.884

Conclusion:

As all the results are show in the tabular form it can be clearly seen that mesh size really makes a difference in evaluating stress values with better accuracy. In the above simulation it’s been seen that mesh with 6mm consist of elements 14171 and mesh with 4mm size consist of 14983. If we compare both the results then within both of the mesh there is not much difference in the stress values and strain values. Both of values are nearby so instead of using more refined mesh of 4mm we can also opt for 6mm mesh. This will provide us the result faster with precise accuracy and accordingly used for various purpose. From the previous challenge and the current we can observe that changing the element and mesh size doesn’t have much impact unless and until we change the boundary conditions. Deformation is same for mesh sizes of 4mm, 5mm & 6mm.

Note: All the files of different mesh are attached for reference with their mesh size at the end of filename. Animated Videos of each simulation is also been attached for reference.File name Bevel Gear Project that consist of all three simulation is attahed in Workbench format.