Week 1 Spur Gear Challenge

Objective:

The objective of the challenge was to compare three spur gear models of different materials which are cast bronze, cast iron and cast steel. The materials that I used was Bronze C51000, Carbon Steel 1020 annealed and Cast Iron EN GJl 100. The objective was to compare these 3 models find out possible area of fracture and select which material is best for this application.

All three models used an Element size of 1.5mm.

The images are attacehed in the order of Bronze, Iron and Steel.

Deformation

Comparing the results of deformation we cannot select the material as all 3 materials gave the same amount of deformation and the point of maximum deformation is laso at the same point. The maximum deformation was at 30mm.

Stress

Comparing the stresses produced on the gears the maximum amount of stress is produced in Cast steel at 310.53MPa. the least amount of stress is developed in the gear made of Cast Bronze at 255.84 MPa whil the gear made of Cast iron faired well with maximum stress of 261.59 MPa. In all the materials the maximum stress occured at the same point which was at the foot of the gears teeth.

Stress Intensity

Comparing the stress intensity of all 3 materials there is one thing in common the maximum stress occuring and the maximum stress intensity coincides in every case. There is a similar trend developing here just like in the case of maximum stress. Highest stress intenstiy is for Cast steel at 334.52 MPa followed by Cast Iron at 270.03 MPa and finally by Cast Bronze at 267.03 MPa. Also just as the maximum stress the maximum stress intensity occurs at the foot of the gear tooth.

Fracture possibility:

Fracture occurs when the stress density is higher than the materials yield strength. Going with the yield strengths data given in the engineering data from Ansys Bronze has the highest yield strength (505 MPa) followed by Steel (293.5 MPa) and finally iron (79.81). So fracture will occur on both modesl made by Steel and Iron. the only material which wont fracture is Bronze. Since both maximum stress and maximum stress intensity occured at the foot of the gears teeth it is the point where the fracture will occur.

Material	CAST BRONZE	CAST IRON	CAST STEEL
YIELD STRENGTH (MPa)	505	79.81	293.5
MAX. DEFORMATION (mm)	30	30	30
MAX. STRESS (MPa)	255.84	261.59	310.53
MAX. STRESS INTENSITY(MPa)	267.03	270.03	334.52

Material Selection

I would select bronze to make this gear as it is the only gear which did not fracture or develop enough stress to fracture the gear during the simulation.