Investigation of the effect of hardness on gear tooth failure by bending fatigue test

Abstract

This study investigated the effect of hardness change on the types of damage caused by fatigue damage at the symmetrical and asymmetrical gear teeth made of AISI 4140 material. In the experimental study, gear teeth were subjected to load by the Single Tooth Bending Fatigue (STBF) test method. The gear teeth were loaded with different torque values to examine the fatigue damage. Damages in symmetrical gears happened as a result of the progression of cracks in the tooth root region. In asymmetric gears, on the other hand, it has been observed that the way damage changes rely on the load, the number of cycles, and the hardness. In asymmetrical teeth, relatively high cycle numbers were reached in the tests performed with low torque. The tooth flank damage occurred as a result of crack growth in the teeth at relatively low loads and high cycles.