Week 1 Spur Gear Challenge

1) Objective: To carry out static structural analysis to find a) Equivalent stress b) Total deformation and c) Stress Intensity for three different materials which are a) Cast iron, b) Cast steel c) Cast bronze and conclude which material is best suited for applications based on results.

2) Stress Intensity : The stress intensity factor is the magnitude of the stress singularity at the tip of a mathematically sharp crack in a linear elastic material. It describes the stress state at a crack tip, is related to the rate of crack growth and is used to establish failure criteria due to fracture.

3) Case setup

Case 1: 

Material: Cast iron

Geometry : exported step file of spur gear

Boundary conditions : 

• 1) Contacts : frictional between both gears
• 2) Joints: Revolute to ground for both gears

Analysis setting:

• No. of steps = 6
• Initial Time setup = 0.2 s
• Min. Time setup = 5.e-002 s
• Max. Time setup = 0.5s

Joint load:

• Rotation (cw) 120 degrees in one gear
• Moment (ccw) 10N in second gear

Case 2:

• Material: Cast Bronze
• all other setting for analysis are same as above

Case 3:

• Material: Cast Steel
• all other setting for analysis are same as above

4) Result: Attached document for the results.

5) Conclusion: 

Result/Material	Cast Iron	Cast Bronze	Cast Steel
Max. Equivalent stress (MPa)	465.32	275.81	283.61
Max. Displacement (mm)	30	25.98	25.98
Max. Stress Intensity (MPa)	525.49	296.81	313.87

As the stress intensity for cast iron is greater among three material, it can sustain more fatigue load before any fracture, hence increasing life of the gear.