Spur Gear Advanced Structural Analysis By Using 3 Different Materials For Gears By Using ANSYS Workbench

Spur Gear Challenge

Advanced Structural Analysis using ANSYS Workbench

Compare the results obtained by using 3 different materials for gears and write a detailed report explaining the results obtained.

SPUR GEAR: Spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk with teeth projecting radially. Though the teeth are not straight-sided (but usually of special form to achieve a constant drive ratio mainly involute but less commonly cycloidal), the edge of each tooth is straight and aligned parallel to the axis of rotation. These gears mesh together correctly only if fitted to parallel shafts. No axial thrust is created by the tooth loads. Spur gears are excellent at moderate speeds but tend to be noisy at high speeds

Spur gear teeth are manufactured by either involute profile or cycloidal profile. Most of the gears are manufactured by involute profile with 20° pressure angle. When two gears are in mesh at one instant there is a chance to mate involute portion with non-involute portion of mating gear. This phenomenon is known as \"interference\" and occurs when the number of teeth on the smaller of the two meshing gears is less than a required minimum. To avoid interference we can have undercutting, but this is not a suitable solution as undercutting leads to weakening of tooth at its base. In this situation Corrected gears are used. In corrected gears Cutter rack is shifted upwards or downwards.

Stress Intensity :-

Engineers are interested in the maximum stress near the crack tip and whether it exceeds the fracture toughness. Thus, the stress intensity factor K is commonly expressed in terms of the applied stresses at and .

For example, for a through crack in an infinite plate under uniform tension , the stress intensity factor is :-

where: \'a\' is one half of the width of the through crack. The dimension of K is :-

Objective 1:

• Case 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.

Meshing : Element Size = 1mm & Mesh Type = Tetrahedron/ Hexa. (Automatic) for all Cases.

Material Properties of CAST IRON (Ductile)

Equivalent stress: - Max. =318.2 MPa & Min. = 2.2279e-5 MPa

Total Deformation: - Max. =1.5701 mm & Min. = 0.95936 mm

Stress intensity:- Max. = 325.32 MPa & Min. = 2.5409e-5 MPa

Pressure :- Max. =425.36 MPa & Min.= 0 MPa

• Case 2: Using Cast Steel as material, perform the same analysis for the results as in Case1.

Material Properties of CAST STEEL.

Equivalent stress: - Max. = 381.33 MPa & Min. = 7.0999e-7 MPa

Total Deformation: - Max. = 30 mm & Min. = 18.5 mm

Stress intensity:- Max. = 290.55 MPa & Min. = 5.3122 MPa

Pressure :- Max. = 443.87 MPa & Min. = 0 MPa

• Case 3: Using Cast Bronze as material, perform the same analysis for the results as in Case1.

Material Properties of CAST BRONZE.

Equivalent stress: - Max. = 379.61 MPa & Min. = 1.42e-6 MPa

Total Deformation: - Max. = 1.5701 mm & Min. = 0.9566 mm

Stress intensity:- Max. = 156.82 MPa & Min. = 7.3888e-7 MPa

Pressure :- Max. = 432.16 MPa & Min. = 0 MPa

Objective 2:

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

Comparision Between 3 Materials of Gears.

Sr. No.	Material	Equivalent Stress (MPa)	Total Deformation (mm)	Stress Intensity (MPa)
1	Cast Iron (Ductile)	Max. =318.2	Max. =1.5701	Max.= 325.32
Min. = 2.2279e-5	Min. = 0.95936	Min. = 2.5409e-5
2	Cast Steel	Max. = 381.33	Max. = 30	Max. = 290.55
Min. = 7.0999e-7	Min. = 18.5	Min. = 5.3122
3	Cast Bronze	Max. = 379.61	Max. = 1.5701	Max. = 156.82
Min. = 1.42e-6	Min. = 0.9566	Min. = 7.3888e-7

Conclusion :-

1. From Above compression :- Equivalent Stress :- 2>1>3

Total Deformation :- 2>(1=3)

Stress Intensity :- 1>2>3

2. As per my analysis done in Ansys, and comparing the above results, I prefer Cast Iron material for manufacturing of the gear because it gives less Equivalent Stress at the time of functioning.

3. Apart from that we also can choose Cast Bronze material for the manufacturing of the gears because it gives less Stress Intensity where the crack initation is started.

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