Week 1 Spur Gear Challenge

Stress Intensity on Spur Gear.

Objective 1:

• Case 1:
  

Using Cast Iron(ductile) as a material, carry out a static structural analysis to find out Equivalent stress, Total deformation and Stress intensity(Learn about what stress intensity is). Find location for possible fracture

• Case 2:

Using Cast Steel as material, perform the same analysis for the results as in Case 1.

• Case 3:

Using Cast Bronze as material, perform the same analysis for the results as in Case 1.

Objective 2:

Write a detailed report comparing the results of the three cases and conclude which material would you recommend based on these results.

Procedure:

Case1:

For Case 1, Static Structural Analysis is carried out on Spur Gear. The material is Cast Iron (Ductile) and the analysis is carried out on Ansys Workbench. The geometry of the model is imported on the Ansys Workbench for analysis.

The Property of the material is stated below:

Density: 6999 kg/m³

Bulk Modulus: 6.2111E+10 Pa

Poisson’s Ratio: 0.26

Young’s Modulus: 8.944E+10 Pa

The model is meshed using Ansys Mesher with an element size of 1 mm, and a patch conforming method using tetrahedrons was employed. This is done to get the best refinement within the limitation of Ansys Academic License.

A mesh metric that identifies the elements according to their quality was employed and it can be seen that element of lowest quality are minimal. Most of the elements have very high quality in the range of 0.7-1. Hence, the mesh is of acceptable quality. The meshed model is shown in image below:

The simulation is then run and results are obtained.

Case 2:

For Case 2, Static Structural Analysis is carried out on Spur Gear. The material is Cast Steel and the analysis is carried out on Ansys Workbench. The geometry of the model is imported on the Ansys Workbench for analysis.

The Property of the material is stated below:

Density: 7820 kg/m³

Young’s Modulus: 2.03E+11 Pa

Poisson’s Ratio: 0.3

Bulk Modulus: 1.697E+11 Pa

Case 3:

For Case 3, Static Structural Analysis is carried out on Spur Gear. The material is Cast Bronze and the analysis is carried out on Ansys Workbench. The geometry of the model is imported on the Ansys Workbench for analysis.

The Property of the material is stated below:

Density: 8810 kg/m³

Young’s Modulus: 8E+10 Pa

Poisson’s Ratio: 0.345

Bulk Modulus: 8.6022E+10 Pa

Results:

Total deformation of the 3 cases are compared first.

S.No. Time [s] Minimum [mm] Maximum [mm] Average [mm]

1. 0.2 0.96822 1.5988 1.2672 (Cast Iron)
2. 0.2 0.96822 1.5854 1.2619 (Cast Steel)
3. 0.2 0.96822 1.5949 1.2657 (Cast Bronze)

Equivalent Stress for the 3 cases are compared.

S.No Time [s] Minimum [Mpa] Maximum [Mpa] Average [Mpa]

1. 0.2 2.5444e-005 242.43 8.9336 (Cast Iron)
2. 0.2 6.8125e-006 266.31 8.9284 (Cast Steel)
3. 0.2 2.1937e-007 245.35 8.9593 (Cast Bronze)

Stress Intensity of 3 cases are compared.

S.No Time [s] Minimum [Mpa] Maximum [Mpa] Average [Mpa]

1. 0.2 2.6613e-005 255.88 9.7123 (Cast Iron)
2. 0.2 7.5911e-006 282.69 9.7206 (Cast Steel)
3. 0.2 2.5248e-007 262.79 9.7876 (Cast Bronze)

The plot for the total deformation of the Spur Gear is as plotted and is shown in the figure given below:

The plot for the equivalent stress of the Spur Gear is as plotted and is shown in the figure given below:

The plot for the equivalent stress of the Spur Gear is as plotted and is shown in the figure given below:

Since the maximum stress intensity is in this region of the gear i.e 414.88 Mpa, so the location for possible fracture could be the tooth of the gear as shown in the figure below, highlighted by the probe.

Conclusion:

The Analysis was run succesfully, within the limits of the academic license, the simulation for the 3 cases were examined.

On comparison of the Total deformation experienced by the model in 3 cases, only a slight difference in the average value is evident of the order of 0.005 mm with Case 3 (max-min) having a higher value.

On comparison of the Equivalent stress experienced by the model in 3 cases, a slight difference in the average value of is evident of the order of 0.03 Mpa with (Case3-Case 2) having hiegher value.

On comparison of the stress intensity experienced by the model in 3 cases, a slight difference in the average value of is evident of the order of 0.07 Mpa with (Case3-Case 1) having hiegher value. Maximum stress intensity having a difference of 26.81 Mpa.(i.e Cast bronze is having 26.81 Mpa stress intensification than cas iron)

On the basis of these 3 results from analysis point of veiw, case 1 can be choosen because the stress intensity undergone by it on the same amount of tensile force is lesser than the case 2 & Case 3.