Finite Element Analysis of a Gear Tooth using Ansys and Stress Reduction by Stress Relief Hole

Spur gears are used to transmit motion and power from one shaft to another, especially in between two parallel shafts and also used to vary speed and torque. The cost of replacement of spur gear is very high and also the system down time is one of the effect in which these gears are part of system. When gear is subjected to load, high stresses developed at the root of the teeth, these high stresses increase the chances of fatigue failure at the root of teeth of spur gear. The aim of this research paper is to reduce the root filet stress to increase fatigue life of spur gear. This paper present the techniques to reduce root fillet stress in spur gear by introducing the stress relieving features in stress zone. Three teeth of spur gear are taken for study. By using Lewis equation maximum principal stress is calculated by applying the load at tip of tooth. In the same way spur gear is analyzed in ANSYS software for the maximum principal stress. In comparison it is found that both the results are above 900 closed. The maximum principal stress at root fillet of spur gear is calculated in ANSYS is 10% less than theoretical result. By considering the maximum principal stress in ANSYS as a base, further work is carried out in ANSYS. Circular stress relieving features are used at various locations in spur gear to reduce the maximum principal stress. Reduction in principal stress increases fatigue life of spur gear.