Static structural analysis on spur gear

OBJECTIVE:

To perform a static structural analysis on the given model of spur gear to find out Equivalent stress, Total deformation, Stress intensity and location for possible fracture for 3 different cases and to compare the results obtained.

• CASE 1: MATERIAL USED : Cast Iron(ductile)
• CASE 2: MATERIAL USED : Cast Steel
• CASE 3: MATERIAL USED : Cast Bronze

GIVEN MODEL:

MESHING:

Element size:0.8mm

APPLIED CONDITIONS:

CASE 1:

• Material used:
• RESULTS FROM CASE 1:
• Total deformation
• Equivalent stress:
• Equivalent elastic strain:
• Stress intensity:
• Contact Pressure:

CASE 2:

• Material used:
• RESULTS FROM CASE 2:
• Total deformation:
• Equivalent elastic strain:
• Equivalent stress:
• Stress intensity:
• Contact Pressure:

CASE 3:

• Material used:
• RESULTS FROM CASE 3:
• Total deformation:
• Equivalent elastic strain:
• Equivalent stress:
• Stress intensity:
• Contact Pressure:

COMPARISON BETWEEN CASE 1, CASE 2 AND CASE 3:

• The values of total deformation is same for all three cases.
• The maximum stress intensity is higher for case 1 and lower for case 3.
• The mximum von mises stress is higher for case 1 and lower for case 3.
• The mximum equivalent elastic strain is higher for case 3 and lower for case 2.

LOCATION FOR POSSIBLE FRACTURE:

It is seen that the tip region of the gear teeth sufers maximum value of deformation and the value of deformation reduces as we go to the root region.

The stress intensity at the spur gear root region is higher compared to other regions.

Stress intensity at the top region of the teeth in contact

Stress intensity at the bottom region of the teeth in contact

It is clear from the above picture that the stress intensity is higher at base of the teeth. Hence it is a location for possible fracture to take place.

Animations Link: https://drive.google.com/open?id=1lJja1IMrHrVKLFgIeUk2OcV8qvc-tL7Z

CONCLUSIONS:

• From the analysis , it is clear that the von mises stress developed is higher for cast iron(ductile) and is lower for cast bronze.
• Similarly, higher value for stress intensity is seen when the material is cast iron(ductile) and lower value for cast bronze. When the stresses developed are lower, lower will be the chances of fracture.
• Since cast bronze showed the least values for equivalent stress and stress intensity, it would be the best material for the above purpose. Still it may not be economical for this purpose but it is the strongest.
• Whereas, Cast steel showed lower values for stress intensity and equivalent stress when compared to cast iron(ductile), but little higer values than cast bronze. Since cast steel is more economical with stress intensity being very close to cast bronze, it would be the best material for the manufacturing of the spur gear.