Week 1 Spur Gear Challenge

Objective of the Work:

Objective of the work is to simulate Spur gear simulation using different materials like Cast Iron (ductile), Cast Steel, and Cast Bronze as a material for the gears and carry out a static structural analysis to find out Equivalent stress, Total deformation and Stress intensity. After getting all the result need to analyse and compare the results of the three cases and conclude which the best material among all and possible facture zone.

Experimental Procedure:

To carry out Static structural analysis on Ansys workbench, several steps has been followed.

Case-1

1. Engineering Data: This is the first step, where we have to select the material on which the analysis would be carried out. For the Case-1, Cast Iron (Ductile) has been chosen.
2. Import Geometry: After assigning the base material of the geometry, the model has been imported in Ansys.
3. Model: This step is the major step of Analysis. After importing the model, need to click on “Edit” to open the “Model Window” where we can assign several constraint and Boundary condition.

Step-1(Geometry): Under geometry click on the imported model and assign the material individually.

Step-2 (Connections): Under Connection have to insert “Contacts”, where have to assign “Frictional Contacts” and assign the Contact faces of the gears. After Contacts has been given, need to assign “Joints “as a type “Revolute joint” for the both Gears.

4. Mesh: Element size as 1.00 mm has been chosen and Smoothening has been kept Low for meshing the model.
5. Static Structural:

Step-1 (Analysis Setting): Under Analysis setting several parameters have been modified according to the problem. No. of Steps kept as 6, Auto Time Stepping kept as On, Initial Time Step 0.2 sec, Minimum Time Step 5e- ⁰⁰² sec, Maximum Time Step 0.5 sec and all Solver Controls have been kept as Programmed Controlled.

Step-2 Need to Assign the Joints for the individual gears. DOF has been kept as on Z axis and Magnitude has been given in Tabulated Data, where in one gear it has been kept as Degree of rotation (30 Degree increment) and on the other gear Moment has been given in the Tabulated data as 10 N-m on each.

Step-3 (Contact Tool): To get the Contact Pressure point on the Gear Tooth, have to insert Pressure, under contact tool.

6. Solution: To get the result as per the objective of the work have to insert Equivalent Stress, Total Deformation and Stress Intensity.
7. Solve: To obtain the result click on Solve.

*** The same procedure has been followed up for the Case-2 and Case-3 (Only the material has been changed according to the Case2 & Case3 requirements).

Result & Discussion:

Case-1 (Material: Cast Iron- Ductile)

1. Total Deformation: The ductile iron has higher elongation. As for the ductile iron it has 18% elongation. The maximum deformation result got 30mm and Minimum deformation: 18.5 mm.
2. Equivalent Stress: Maximum Stress: 386.49 Mpa. And Minimum Stress: 3.339e^-06
3. Stress Intensity: Maximum Stress Intensity: 410.31 Mpa and Minimum Stress Intensity 3.5139e-⁰⁶ Mpa
4. Pressure: The maximum contact pressure got 422.24 Max.

Case-2 (Cast Steel)

1. Total Deformation: The maximum deformation result got 30mm and Minimum deformation: 18.5 mm.
2. Equivalent Stress: Maximum Stress: 244.35 Mpa. And Minimum Stress: 1.0251e^-05
3. Stress Intensity: Maximum Stress Intensity: 261.92 Mpa and Minimum Stress Intensity 1.1238e-⁰⁵ Mpa
4. Pressure: The maximum contact pressure got 426.94 Max.

Case-3 (Cast Bronze)

1. Total Deformation: The maximum deformation result got 30mm and Minimum deformation: 18.5 mm.
2. Equivalent Stress: Maximum Stress: 371.94 Mpa. And Minimum Stress: 3.2093e^-05
3. Stress Intensity: Maximum Stress Intensity: 399.13 Mpa and Minimum Stress Intensity 3.6279e-⁰⁵ Mpa
4. Pressure: The maximum contact pressure got 322.48 Max.

Analysis on all three cases:

• The Maximum & minimum Equivalent stress has been found among these three case is Cast Iron (Ductile) and Cast Steel respectively.
• The Deformation value are the same in all three cases.
• The Maximum and Minimum Stress Intensity has been found on Cast and Cast Steel respectively.
• The maximum and minimum Contact pressure has been found on Cast Steel and Cast Bronze respectively.
• The moderate result of Equivalent stress and Stress Intensity has been found on Cast Bronze.

Conclusion:

• Considering the Equivalent stress, the maximum values obtained on Cast Iron, Cast Steel and Cast Bronze are 386.49 Mpa, 244.35 Mpa and 371.94 Mpa respectively. The ductile iron has higher elongation. As for the ductile iron it has 18% elongation. In all the cases the values are below the UTS limit of the material which are 448 Mpa, 420 Mpa & 550 Mpa. But in case of Cast Iron the value is slightly in higher side. So, high stress has been generated in Cast Iron gears.
• The Total Deformation value has been same in all three cases which is 30 mm.
• Maximum stress intensity developed on Cast Iron and its stress is also very high. Though the material is ductile but due to high stress intensity it can go fatigue failure under loading condition for a long cycle run. The stress intensity result of Cast Bronze is high, but due to its high ductility and higher UTS value, it can be safe to manufacture gears with Cast Bronze. But cost would also higher.
• The optimum result got from Cast steel. Because the maximum stress and intensity value got from Cast steel are much lower than its yield limit. Thus design is very safe in terms of fatigue failure for long cycle run and from the cost perspective its lesser that other two. So, we can say that from cost, material and Static structural analysis perspective Cast Steel would be better choice in terms of feasibility.