Week 1 Spur Gear Challenge
Stress analysis on spur gear assembly of different materials:
Aim: To perform stress analysis on Spur gear assembly made up of 3 materials of cast iron,cast steel & bronze cast with material specifications shown in the image below:
Cast Iron:
Cast Steel:
Cast Bronze:
Stress Intensity: Stress intensity factor is a concept used in fracture mechanics to measure stress concentration at the crack tip.In safety design, it is used to evalute with material's cricital value at failure points,were stresses are high.
Steps Followed:
The following connections are given to spur gear assembly of all 3 different materials:
Each gear having 13 teeths & gear ratio of 1, so we have to select 26 faces of each gears for assembly purpose with frictional connection type. Behaviour is symmetric,Formulation Augmented Lagrange with interface of Adjust to touch.
We provide joints of body to ground & revolute type after selecting inner surface of both gears for rotation & different geometric selection for the proper rotation of both the gears.
Analysis:
The analysis is doen taking 6 number of steps as for each gear will rotate 30 degree angle.
Auto time stepping On, Define Time,Intial time step of 0.2s,Minimum time step 0.05s & Maximum time step 0.5s.
Rotation is given to one of the spur gear, for each second gear will rotate by 30 degree and by the end of 6 s it will be rotated by 180 degrees.
One gear given rotation while the other is given torque of 10 Nmm in all 3 different material gear assembly.
Result:
Cast Iron:
Equivalent Von Mises Stress:
Total Deformation:
Stress Intensity:
Stress vs Time Plot:
Values of stress with time in Tabular fomat:
Maximum stress in above simulation is 402.37 MPa for cast iron which is more than yield strength of
79.81 MPa, so this gear assembly system wil fail
Cast Bronze:
Eqivalent Von Mises Stress:
Total Deformation:
Stress Intensity:
Stress vs Time Plot:
Values of stress with time in Tabular fomat:
Maximum stress in above simulation is 410.98 MPa for bronze cast which is again more than yield strength of 144 MPa. So this gear assembly system fails.
Cast Steel:
Eqivalent Von Mises Stress:
Total Deformation:
Stress Itensity:
Stress vs time plot:
Stress vs Time plot in tabular form:
Maximum stress obtained is 419.37MPa for cast steel so it is more than yield tensile strength of 349 MPa.So this gear assembly system fails.
Conclusions:
All datas below are in MPa.
| Maximum Stress | Tensile Yield Strength | Difference | |
| Cast Iron | 402.37 | 79.81 | 322.56 |
| Bronze Cast | 410.98 | 144 | 266.98 |
| Cast Steel | 419.37 | 349 | 70.37 |
From the above table which we get after stress analysis of Spur Gear assembly in Ansys Workbench, we can conclude that highest maximum stress occurs for cast steel though it has least difference between Tensile yield strength & maximum stress compared to bronze cast or cast iron.So Cast Steel material must be preferred over Bronze Cast or Cast Iron materials.
However from safety point of view all 3 gear assembly system will be failing hence not applicable in real life examples.
Animation of Cast Steel Material is attached below.