Week 1 Spur Gear Challenge

Objectives

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

1. Cast Iron Simulation Results

The solver settings are as described in the video.

Equivalent stresses in a cast iron spur gears are as shown in figure 1.

Figure 1 Equivalent(von-mises) stresses in cast iron spur gear

The equivalent(von-mises) stresses are higher at the tooths meshing into each other. This is obvious due to normal stresses developed, when tooths come in contact to each other. The maximum stress 75.874 MPa is at the surface of tooth which has just come into contatc. However, for the teeths which are free to roatate, stresses are very low of the order -9.

Total deformation in the spur gear is as shown in figure 2.

Figure 2 Total deformation in cast iron spur gear

The total deformation is same in every teeth, highest being at the top face of the teeth. The lowest defomation is lowest in below the base circle. This is obvious tooth part coming in contact to each other experiance highest forces, thus are having highest deformations.

The stress intensity is as shown in figure 3.

The stess intensity factor is the magnitude of the stress singularity at the tip of a mathematically sharp crack in a linear elastic material.

The stress intensity is highest in the tooth at the left gear leaving the contact with the right gear. Hence, is the location for the possible fracture. The teeths in the conatact experiences highest stress intensity, as they experience high normal reactions forces. On the other hand rest of the gear has very low stress intensity as they are free to rotate.

2. Comparison of simulaiton results for cast iron, cast steel, cast bronze gears.

Cast iron spur gears shoule be preferred as they have lowest max equivalent(von-mises) stress(75.874) and max stress intensity(86.996) as shown in table 1,2 ,3.

Table 1 Comparision of equivalent(von-mises) stress, total deformation, stress intensity for cast iron, cast steel, and cast bronze gears

S.No.	Max. Equivalent stress	Max. Total deformation	Max. Stress Intensity
Cast Iron	159.54	28.978	182.76
Cast Steel	190.61	28.978	218.43
Cast Bronze	75.874	28.978	86.996

Table 2 Comparision of equivalent(von-mises) stress, total deformation, stress intensity for cast iron, cast steel, and cast bronze gears

S.No.	Min. Equivalent stress	Min. Total deformation	Min. Stress Intensity
Cast Iron	1.0182e-8	17.87	1.1529e-8
Cast Steel	1.7072e-8	17.87	1.9513e-8
Cast Bronze	7.0142e-9	17.87	7.4443e-9

Table 3 Comparision of equivalent(von-mises) stress, total deformation, stress intensity for cast iron, cast steel, and cast bronze gears