Surface Durability of Spur Gears at Hertzian Stresses Over Shakedown Limit

1974 ◽  
Vol 96 (2) ◽  
pp. 359-372 ◽  
Author(s):  
Akira Ishibashi ◽  
Taku Ueno ◽  
Shigetada Tanaka
Keyword(s):  
Fatigue Testing ◽  
Testing Machine ◽  
Carbon Steels ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Load Testing ◽  
Short Period ◽  
Hertzian Contact Stress ◽  
Surface Durability ◽  
Shakedown Limit

Using a new type of gear-load testing machine and a disk-type rolling fatigue testing machine designed and made by the authors, the upper limits of Hertzian contact stress allowable on rolling contact surfaces were investigated. It was shown conclusively that gears and rollers made of soft carbon steels could be rotated beyond 108 revolutions at Hertzian stresses over shakedown limit (≈ 0.4 HB). In the case of gears, pits having a pitting area ratio of 0.04 percent occurred during 1.16 × 108 rotations at a Hertzian stress of 0.50 HB. However, no pitting occurred on the roller rotated through 1.20 × 108 revolutions at a Hertzian stress of 0.71 HB, although appreciable changes in texture were observed at the subsurface. In order to rotate gears or rollers at Hertzian stresses over shakedown limit, their surface must either be very smooth initially or after a short period of running, and an oil film must be formed between contacting surfaces.

Effect of Lubricant on Surface Rolling Contact Fatigue Cracks

2010 ◽  
Vol 97-101 ◽  
pp. 793-796 ◽  
Author(s):  
Khalil Farhangdoost ◽  
Mohammad Kavoosi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Element Analysis ◽  
Crack Face ◽  
Hertzian Contact Stress ◽  
Model Of Friction

This study performed the finite element analysis of the cycle of stress intensity factors at the surface initiated rolling contact fatigue crack tip under Hertzian contact stress including an accurate model of friction between the faces of the crack and the effect of fluid inside the crack. A two-dimensional model of a rolling contact fatigue crack has been developed with FRANC-2D software. The model includes the effect of Coulomb friction between the faces of the crack. The fluid in the crack was assumed not only to lubricate the crack faces and reduce the crack face friction coefficient but also to generate a pressure.

Tooth Surface Fatigue Strength of Normalized Steel Conical Involute Gears

2000 ◽  
Author(s):  
Tatsuya Ohmachi ◽  
Koji Iizuka ◽  
Hidenori Komatsubara ◽  
Ken-ichi Mitome
Keyword(s):  
Fatigue Strength ◽  
Contact Stress ◽  
Testing Machine ◽  
Hertzian Contact ◽  
Tooth Surface ◽  
Paper Test ◽  
Surface Fatigue ◽  
Involute Gears ◽  
Conical Gears ◽  
Hertzian Contact Stress

Abstract The tooth surface fatigue strength of the conical involute gear is evaluated in this paper. Test gears are straight intersecting-axis conical gears. The material of the test gear is normalized steel. The power circulating testing machine is used in this experiment. The circulating torque is kept constant and the number of times of contact is 107. The tooth surface life is evaluated by the pitting area rate. The critical value of the circulating torque is found between 147 N·m and 157 N·m. For critical torque, the pitting area rate does not progress over 4%. The Hertzian contact stress of the test gear is calculated at the circulating torque. The contact stress should be evaluated in consideration of the wearing effects.

Evaluation of the fatigue life of a sintered machine element under the sliding/rolling contact condition based on fracture mechanics

2002 ◽  
Vol 37 (4) ◽  
pp. 327-336
Author(s):  
A Yoshida ◽  
Y Ohue ◽  
H Ishikawa
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Testing Machine ◽  
Element Model ◽  
Contact Condition ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Stress Intensity Factor Range

In order to evaluate the surface durability of sintered machine elements, the fatigue lives of 28 kinds of sintered roller under a sliding/rolling contact condition were estimated using Paris's law based on linear fracture mechanics. The fatigue tests were conducted using a two-cylinder testing machine. The stress intensity factor for the mode II under the Hertzian contact condition was calculated using the finite element model. The value of the stress intensity factor became larger as the crack length became longer to the contact surface, and the value of the stress intensity factor range was independent of the crack angle. It could be clarified that the fatigue lives of the sintered rollers depended on the pore diameter and the hardness. It was obvious that the pore distribution has to be taken into consideration to estimate the fatigue lives of the sintered rollers more precisely.

Effect of Shot Peening Coverage on Fatigue Strengths of Steels and Aluminum Alloy

2015 ◽  
Vol 1102 ◽  
pp. 33-36
Author(s):  
Junji Sakamoto ◽  
Yong Sung Lee ◽  
Seong Kyun Cheong
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Strength ◽  
Shot Peening ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Carbon Steels ◽  
Medium Carbon Steels ◽  
Negative Effect ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

The relations between shot peening coverage and fatigue strength in the quenched-tempered and annealed medium-carbon steels and aluminum alloy A7075-T6 were experimentally studied using a rotating bending fatigue testing machine. It was found that the fatigue strengths of the annealed steel and aluminum alloy were increased by shot peening. On the other hand, the fatigue strength of the quenched-tempered steel were not increased by shot peening. Same shot peening condition causes the positive effect and the negative effect depending on the type of material. Moreover, the valuable coverage might depend on the type of material. More detailed work is necessary to resolve the issue.

Spalling Fatigue Life Assessment of Surface Hardened Sintered Gears Based on Fracture Mechanics

2003 ◽  
Author(s):  
Yuji Ohue ◽  
Akira Yoshida ◽  
Masanori Seki
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Testing Machine ◽  
Fem Analysis ◽  
Induction Hardening ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Life Assessment ◽  
Hertzian Contact ◽  
Ion Nitriding

In order to evaluate the surface durability of surface-hardened sintered gears, the fatigue lives of 5 kinds of sintered gears and 28 kinds of sintered rollers under sliding-rolling contact conditions were examined and estimated based on the fracture mechanics. The sintered gears and rollers were surface-hardened by induction-hardening and ion-nitriding. The fatigue tests were conducted using a power circulating gear testing machine and two cylinder testing machines. The pore distributions included in the sintered materials were observed and were analyzed statistically. The failure mode of the sintered gears and roller was mainly spalling. The stress intensity factor obtained by FEM analysis for the mode II under a condition of Hertzian contact became larger as the crack length became longer. The estimation of fatigue life of the sintered gears and rollers was attempted using the pore distributions and the fracture mechanics. The estimated fatigue lives were almost the same as the tested fatigue ones. Therefore, it could be said that the crack propagation of the sintered gears and rollers depended on the pore size and hardness.

Investigation for Small Shear-Mode Fatigue Cracks in Bearing Steels

2013 ◽  
Vol 750 ◽  
pp. 236-239
Author(s):  
Saburo Okazaki ◽  
Atsushi Kusaba ◽  
Hisao Matsunaga ◽  
Masahiro Endo
Keyword(s):  
Fatigue Crack ◽  
High Speed ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Testing Machine ◽  
Rolling Contact ◽  
Installation Space ◽  
Shear Mode ◽  
Testing Method ◽  
Small Shear

Flaking and spalling caused by rolling contact fatigue associate with a small crack, and a special testing method and machine are required to study the small fatigue crack behavior under shear mode loading. It was found by authors that the behaviors of small shear-mode fatigue cracks from the inclusions and the artificial defects could be successfully observed by applying the fully-reversed torsion coupled with static axial compressive stress. However, the servo-hydraulic fatigue testing machine is quite expensive for purchase and maintenance, and large installation space is necessary for the hydraulic and cooling systems. Moreover, the presence of axial compression significantly lowers the frequency of torsional loading, which consequently results in low testing speed. In this study, a cost-effective, space-saving and high-speed fatigue testing method was newly proposed, and the shear-mode fatigue crack growth tests were carried out by using the developed machine. Based on the obtained experimental data, the potential of the new testing machine is discussed.

Residual Stress Change Due to Rolling Contact of Ball and Roller Bearings

1980 ◽  
Vol 24 ◽  
pp. 215-220
Author(s):  
Kikuo Maeda ◽  
Noriyuki Tsushima ◽  
Hiroshi Muro
Keyword(s):  
Residual Stress ◽  
Contact Stress ◽  
Stress Measurement ◽  
Rolling Bearing ◽  
Bearing Steel ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Compressive Yield Strength ◽  
Rolling Elements ◽  
Hertzian Contact Stress

The life of a rolling bearing is predominantly determined by the contact stress between the rolling elements (ball and roller) and the raceway of inner and outer rings. The contact stress is calculated by assuming Hertzian stress distribution. The maximum Hertzian contact stress Pmax usually ranges from 2000 to 3000 MPa in actual service of rolling bearings. These figures are rather large compared to the compressive yield strength of hardened bearing steel (σys = 2000 MPa). Therefore plastic deformation sometimes occurs under the raceway, creating residual compressive stress. Several investigators have so far reported about the residual stress due to rolling contact. There were, however, few who referred to the residual stress in used bearings and application of residual stress measurement to failure analysis.

On a New Rotating Bending Fatigue Testing Machine

1966 ◽  
Vol 15 (148) ◽  
pp. 49-54
Author(s):  
Minoru KAWAMOTO ◽  
Katsumi SUMIHIRO ◽  
Koji KIDA
Keyword(s):  
Fatigue Testing ◽  
Testing Machine ◽  
Bending Fatigue ◽  
Rotating Bending Fatigue ◽  
Rotating Bending
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