An analysis of the effect of pressure angle change on bending fatigue performance in asymmetrical spur gears

Abstract

In this study, the fatigue performances of symmetrical and asymmetrical spur gears were analyzed by performing single tooth bending fatigue tests. The gears tested were determined to be symmetrical spur gears with a 20 degrees/20 degrees pressure angle, asymmetrical spur gears with a 20 degrees/22 degrees pressure angle, and asymmetrical spur gears with a 20 degrees/25 degrees pressure angle. These gears were made of AISI 4140 material. Single tooth bending fatigue tests were performed under variable loads. Considering the tests performed at the same torque values in asymmetrical spur gears with a 20 degrees/22 degrees pressure angle compared to symmetrical spur gears with a 20 degrees/20 degrees pressure angle, a statistically significant increase in performance was achieved at close to 90%. While gears with 20 degrees/20 degrees and 20 degrees/22 degrees pressure angles break at the tooth root, tooth flank fracture was observed in relatively high numbers of cycles in asymmetric spur gears with a 20 degrees/25 degrees pressure angle. It was observed that the formation of tooth flank damage negatively affected the fatigue performance.