The fatigue strength of carburized gears is influenced by the latent defect in the surface layer. To clarify this influence, the bending fatigue strength of carburized gears with an artificial notch is evaluated in this paper. The notches are processed by wire-cut electrical discharge machining (WEDM) and focused ion beam (FIB) etching to obtain the required depth. The fatigue strength of the tooth with the notch over 35 pm in depth decreases markedly in comparison with the nonnotched tooth. In the case where the notch is shallower than 20 μm, cracks initiated from the notch are not observed and the strength is not reduced. By assuming a crack of the same length as the notch, the stress intensity factor KI is calculated considering the effect of residual stress. The strength expected from the stress intensity factor range is higher than the obtained strength of the gear with the notch.
JSME international journal. Ser. 1, Solid mechanics, strength of materials
JSME international journal. Ser. A, Mechanics and material engineering
JSME international journal. Ser. 3, Vibration, control engineering, engineering for industry
JSME international journal. Ser. C, Dynamics, control, robotics, design and manufacturing
JSME International Journal Series A Solid Mechanics and Material Engineering
JSME International Journal Series B Fluids and Thermal Engineering