Increasing the bending fatigue strength of carburized spur gear teeth by presettin

Presetting is used to enhance the fatigue strength of many products. This study investigated the use of presetting as a method to increase the bending fatigue strength of carburized spur gear teeth. A elastic-perfectly plastic finite element model was formulated to predict the effects of presetting on a gear tooth. The model's results were verified both analytically and experimentally. It was determined that presetting induces compressive residual stress in the area from which fatigue cracks typically originate. Fatigue tests were conducted at three load levels to determine the effect of presetting on fatigue life. At all load levels, improved fatigue life was observed for the preset gear teeth. A statistical analysis was performed to compute the probability that presetting did enhance the fatigue strength of the gear teeth.