Influence of distribution parameters of rough surface asperities on the contact fatigue life of gears

2019 ◽  
Vol 234 (6) ◽  
pp. 821-832
Author(s):  
Wen Yuqin ◽  
Tang Jinyuan ◽  
Zhou Wei
Keyword(s):  
Fatigue Life ◽  
Calculation Method ◽  
Contact Fatigue ◽  
Radius Of Curvature ◽  
Curvature Radius ◽  
Quantitative Calculation ◽  
Distribution Parameters ◽  
Contact Fatigue Life ◽  
The Mean ◽  
Meshing Process

The influence of the distribution parameters of asperities, i.e. mean radius of curvature of asperities β, density of asperities η, and standard deviation of asperity heights σ, on the contact fatigue life of gears is first studied in this paper. Based on the elastic–plastic contact model of asperities, the surface contact pressure and subsurface stress field during the gear meshing process are calculated by the iterative calculation method. According to the multi-axis fatigue life model, the calculation method of fatigue life under different distribution parameters of asperities in the gear meshing process is obtained. The quantitative calculation results of fatigue life and measured distribution parameters of asperities are analyzed. The relationship between the fatigue life and the distribution parameters of asperities on the measured gear surface is calculated and analyzed quantitatively. The following conclusions are drawn: (1) when the roughness value Ra is less than 0.3 µm, the contact fatigue life of gears with rough surfaces is close to that of smooth surfaces; (2) when the roughness value Ra ranges from 0.5 µm to 0.9 µm, the contact fatigue failure occurs near the surface (micro-pitting); (3) under the same roughness value Ra, the contact fatigue life of the gear decreases with the decrease of the density of the asperity and the mean curvature radius of the asperity. The mean radius of curvature of the asperity has a greater influence on the contact fatigue life than the density of the asperity.

Effect of Grain Flow Orientation on Rolling Contact Fatigue Life of AISI M-50

1982 ◽  
Vol 104 (3) ◽  
pp. 330-334 ◽  
Author(s):  
A. H. Nahm
Keyword(s):  
Fatigue Life ◽  
Flow Line ◽  
Flow Direction ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Vacuum Arc ◽  
Type I ◽  
Grain Flow ◽  
Contact Fatigue Life

Accelerated rolling contact fatigue tests were conducted to study the effect of grain flow orientation on the rolling contact fatigue life of vacuum induction melted and vacuum arc remelted (VIM-VAR) AISI M-50. Cylindrical test bars were prepared from a billet with 0, 45, and 90 deg orientations relative to billet forging flow direction. Tests were run at a Hertzian stress of 4,826 MPa with a rolling speed of 12,500 rpm at room temperature, and lubricated with Type I (MIL-L-7808G) oil. It was observed that rolling contact fatigue life increased when grain flow line direction became more parallel to the rolling contact surface.

Influence of ZnDTP on Rolling Contact Fatigue Life under Grease Lubrication

2021 ◽  
Vol 2021.59 (0) ◽  
pp. 05a5
Author(s):  
Hirotomo HOSOI ◽  
Yugo KAMEI ◽  
Hirotoshi AKIYAMA ◽  
Jusei MAEDA ◽  
Masanori SEKI
Keyword(s):  
Fatigue Life ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Grease Lubrication ◽  
Contact Fatigue Life

Evaluation of contact fatigue life of a wind turbine carburized gear considering gradients of mechanical properties

2018 ◽  
Vol 28 (8) ◽  
pp. 1170-1190 ◽  
Author(s):  
Wei Wang ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Zhangdong Sun
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Heavy Duty ◽  
Initial Residual Stress ◽  
Contact Fatigue Life ◽  
Carburized Gear ◽  
Load Conditions

Case hardening processes such as carburizing are extensively applied in heavy-duty gears used in wind turbines, ships, high-speed rails, etc. Contact fatigue failure occurs commonly in engineering practice, thus reduces reliabilities of those machines. Rolling contact fatigue life of a carburized gear is influenced by factors such as the gradients of mechanical properties and profile of initial residual stress. In this regard, the study of contact fatigue life of carburized gears should be conducted with the consideration of those aspects. In this study, a finite element elastic–plastic contact model of a carburized gear is developed which takes the gradients of hardness and initial residual stress into account. Initial residual stress distribution and the hardness profile along the depth are obtained through experimental measurements. The effect of the hardness gradient is reflected by the gradients of yield strength and fatigue parameters. The modified Fatemi–Socie strain-life criterion is used to estimate the rolling contact fatigue life of the heavy-duty carburized gear. Numerical results reveal that according to the Fatemi–Socie fatigue life criterion, rolling contact fatigue failure of the carburized gear will first initiate at subsurface rather than surface. Compared with the un-carburized gear, the rolling contact fatigue lives of the carburized gear under all load conditions are significantly improved. Under heavy load conditions, the carburized layer significantly reduces the fatigue damage mainly due to the benefit to inhibit the accumulation of plasticity. Influence of the residual stress is also investigated. Under the nominal load condition, compared with the residual stress-free case, the existence of the tensile residual stress causes remarkable deterioration of the rolling contact fatigue life while the compressive residual stress with the same magnitude leads to a moderate growth of the rolling contact fatigue life. As the load becomes heavier when plasticity becomes notable, the influence of the initial residual stress on the life is somewhat weakened.

Finite Element Analysis of the Rolling Contact Fatigue Life of Railcar Wheels

2008 ◽  
Vol 575-578 ◽  
pp. 1461-1466
Author(s):  
Byeong Choon Goo ◽  
Jung Won Seo
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Element Analysis ◽  
Railway Vehicles ◽  
Contact Fatigue Life

Railcar wheels and axles belong to the most critical components in railway vehicles. The service conditions of railway vehicles have been more severe in recent years due to speed-up. Therefore, a more precise evaluation of railcar wheel life and safety has been requested. Wheel/rail contact fatigue and thermal cracks due to braking are two major mechanisms of the railcar wheel failure. One of the main sources influencing on the contact zone failure is residual stress. The residual stress in wheels formed during heat treatment in manufacturing changes in the process of braking. Thus the fatigue life of railcar wheels should be estimated by considering both thermal stress and rolling contact. Also, the effect of residual stress variation due to manufacturing process and braking process should be included in simulating contact fatigue behavior. In this paper, an evaluation procedure for the contact fatigue life of railcar wheels considering the effects of residual stresses due to heat treatment, braking and repeated contact load is proposed. And the cyclic stressstrain history for fatigue analysis is simulated by finite element analysis for the moving contact load.

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