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.

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.

Planar Tooth Profile Synthesis for Relative Curvature

2017 ◽  
Author(s):  
Zhiyuan Yu ◽  
Kwun-Lon Ting
Keyword(s):  
Contact Stress ◽  
Tooth Profile ◽  
Hertzian Contact ◽  
Rolling Motion ◽  
Special Cases ◽  
Systematic Methodology ◽  
Hertzian Contact Stress ◽  
Curvature Theory ◽  
The Given ◽  
Tooth Pair

This paper is the first that uses the new conjugation curvature theory [1] to directly synthesize conjugate tooth profiles with the given relative curvature that determines the Hertzian contact stress. Conjugation curvature theory offers a systematic methodology to synthesize the relative curvature for a tooth pair. For any given relative curvature between the contact tooth profiles, a generating point can be located on an auxiliary body. Under the rolling motion among the pinion pitch, the gear pitch and the pitch on the auxiliary body, the generating point will trace fully conjugate profiles on the pinion and gear bodies with the given relative curvature at the instant of the contact. Full conjugation throughout the contact of the profiles is guaranteed with the three instant centers remaining coincident [1]. The methodology is demonstrated with a planar tooth profile synthesis with given relative curvature. One may find that the Wildhaber-Novikov tooth profile, which is known to have low relative curvature and Hertzian contact stress, and its variations become special cases under such methodology.

Hertzian Contact-Stress Deformation Coefficients

1969 ◽  
Vol 36 (2) ◽  
pp. 296-303 ◽  
Author(s):  
Duane H. Cooper
Keyword(s):  
Contact Stress ◽  
Digital Computer ◽  
Approximate Calculation ◽  
Transcendental Equation ◽  
Contact Stresses ◽  
Elliptic Integrals ◽  
Hertzian Contact ◽  
Stress Deformation ◽  
Hertzian Contact Stress

Formulations are given for the coefficients λ, μ, ν defined by Hertz in terms of the solution of a transcendental equation involving elliptic integrals and used by him to describe the deformation of bodies subjected to contact stresses. Methods of approximate calculation are explained and errors in the tables prepared by Hertz are noted. For the purpose of providing a more extensive and more accurate tabulation, using an automatic digital computer, these coefficients are reformulated so that a large part of the variation is expressed by means of easily interpreted elementary formulas. The remainder of the variation is tabulated to 6 places for 100 values of the argument. Graphs of the coefficients are also provided.

Tooth Surface Contact Fatigue Reliability Analysis of Cycloidal Gear Based on Monte-Carlo

2012 ◽  
Vol 605-607 ◽  
pp. 811-814 ◽  
Author(s):  
Tian Min Guan ◽  
Jiang Bo Li ◽  
Lei Lei
Keyword(s):  
Monte Carlo ◽  
Fatigue Strength ◽  
Reliability Analysis ◽  
Contact Stress ◽  
Contact Fatigue ◽  
Tooth Surface ◽  
Fatigue Reliability ◽  
Contact Fatigue Strength ◽  
Design Variables ◽  
Distribution Laws

All sorts of design variables and parameters are often regarded as fixed values in the traditional design, it cannot describe quantitatively how well the products are safe. It is necessary to make a reliability analysis of cycloidal gear, which is the key part of FA pin-cycloidal transmission, this paper uses Monte-Carlo method to simulate and test the distribution laws of the contact stress and the contact fatigue strength of cycloidal gear, which indicates that the contact stress obeys the normal distribution and the contact fatigue strength obeys the lognormal distribution, besides, makes a sensitivity analysis of the random parameters, all these work lay the foundation for the reliability analysis of the whole reducer.

A Simplified Approach to Predict Elastic Pressure Distribution in Non-Hertzian Contact Stress Problems

1991 ◽  
Vol 113 (2) ◽  
pp. 218-223 ◽  
Author(s):  
L. Nayak
Keyword(s):  
Numerical Methods ◽  
Pressure Distribution ◽  
Contact Stress ◽  
Normal Load ◽  
Hertzian Contact ◽  
Two Dimensional ◽  
Simple Method ◽  
Simplified Approach ◽  
Design Engineers ◽  
Hertzian Contact Stress

An approximate but simple method to predict elastic pressure distribution in non-Hertzian contact stress problems has been developed using the two-dimensional Hertz relations and experimentally observed footprint shapes. Predicted pressures have been compared with results available from other numerical methods and are found to be quite satisfactory. The method has been applied to determine pressure distribution in wheel-rail contact under the normal load only. Because of its simplicity and reasonably accuracy in predicting pressure it can be readily used by industrial design engineers for many practical problems of contact mechanics.

Effect of Slider Burnish on Disk Damage During Dynamic Load/Unload

1998 ◽  
Vol 120 (2) ◽  
pp. 332-338 ◽  
Author(s):  
M. Suk ◽  
D. Gillis
Keyword(s):  
Contact Stress ◽  
Disk Surface ◽  
Hertzian Contact ◽  
Radius Of Curvature ◽  
Air Bearing ◽  
Head Disk Interface ◽  
Bearing Surface ◽  
Disk Interface ◽  
Current Design ◽  
Hertzian Contact Stress

Two of the most difficult issues to resolve in current design of head/disk interface in magnetic recording devices are stiction and durability problems. One method of overcoming these problems is by implementing a technology known as load/unload, where the system is designed so that the slider never touches the disk surface. One potential problem with this type of system is slider/disk contact induced disk defects. The objective of this paper is to show that the likelihood of disk scratches caused by head/disk contacts during the load/unload process can be significantly decreased by rounding the edges of the air-bearing surface. Using the resistance method, we observe that head/disk contacts burnish the corners of the slider and thereby decrease exponentially with load/unload cycles. A well burnished slider rarely causes any disk damage thus resulting in an interface with significantly higher reliability. A simple Hertzian contact stress analysis indicates that the contact stress at the head/disk interface can be greatly decreased by increasing the radius of curvature of the air-bearing surface edges.

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