scholarly journals The Influence of Pulling Up on Micropitting Location for Gears with Interference Fit Connections of Their Conical Surface

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1224
Author(s):  
Layue Zhao ◽  
Yimin Shao ◽  
Minggang Du ◽  
Yang Yang ◽  
Jixuan Bian
Keyword(s):  
Boundary Lubrication ◽  
Gear Tooth ◽  
Sliding Contact ◽  
Conical Surface ◽  
Dynamic Loads ◽  
Interference Fit ◽  
Bending Fatigue ◽  
Lubrication Regimes ◽  
Surface Fatigue ◽  
Reducing Gear

Micropitting is a surface fatigue phenomenon that occurs in Hertzian type of rolling and sliding contact that operates in elastohydrodynamic or boundary lubrication regimes and can progress both in terms of depth and extent. If micropitting continues to propagate, it may result in reducing gear tooth accuracy, increasing dynamic loads and noise. Eventually, it can develop into macropitting and other modes of gear failure such as flank initiated bending fatigue. Micropitting has become a particular problem in the gear surface fatigue. Usually micropitting initiates in the dedendum of the driver and driven at the asperities on the surface. However, the authors found for some gears with interference fit connections of their conical surface, micropitting on the pinion occurs in the addendum. This study attempted to find the reason using a 3D–TCA method based on ISO/TR 15144-1 to predict the micropitting and try to understand the key influence likely to affect micropitting location.

Effects of Moving Speeds of Dynamic Loads on the Deflections of Gear Teeth

1981 ◽  
Vol 103 (2) ◽  
pp. 357-363 ◽  
Author(s):  
K. Nagaya ◽  
S. Uematsu
Keyword(s):  
Dynamic Response ◽  
Timoshenko Beam ◽  
Gear Tooth ◽  
Bending Moment ◽  
Dynamic Loads ◽  
Gear Teeth ◽  
Moving Speed

For the dynamic response problems of gear teeth, the dynamic loads which act upon the gear teeth should be considered as a function of both the position and the moving speed. In previous studies, the effects of the moving speed have not been considered. In this paper the effects of the moving speed of dynamic loads on the deflection and the bending moment of the gear tooth are investigated. The results are obtained from the elastodynamic analysis of the tapered Timoshenko beam.

Gear root bending strength: a comparison between Single Tooth Bending Fatigue Tests and meshing gears

2021 ◽  
pp. 1-17
Author(s):  
Luca Bonaiti ◽  
Ahmed Bayoumi Mahmoud Bayoumi ◽  
Franco Concli ◽  
Francesco Rosa ◽  
Carlo Gorla
Keyword(s):  
Failure Modes ◽  
Bending Strength ◽  
Gear Tooth ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Gear Design ◽  
Single Tooth ◽  
Actual Strength ◽  
Meshing Gears ◽  
Definition Of

Abstract Gear tooth breakage due to bending fatigue is one of the most dangerous failure modes of gears. Therefore, the precise definition of tooth bending strength is of utmost importance in gear design. Single Tooth Bending Fatigue (STBF) tests are usually used to study this failure mode, since they allow to test gears, realized and finished with the actual industrial processes. Nevertheless, STBF tests do not reproduce exactly the loading conditions of meshing gears. The load is applied in a pre-determined position, while in meshing gears it moves along the active flank; all the teeth can be tested and have the same importance, while the actual strength of a meshing gear, practically, is strongly influenced by the strength of the weakest tooth of the gear. These differences have to be (and obviously are) taken into account when using the results of STBF tests to design gear sets. The aim of this paper is to investigate in detail the first aspect, i.e. the role of the differences between two tooth root stress histories. In particular, this paper presents a methodology based on high-cycle multi-axial fatigue criteria in order to translate STBF test data to the real working condition; residual stresses are also taken into account

scholarly journals Pitting and Bending Fatigue Evaluations of a New Case-Carburized Gear Steel

2007 ◽  
Author(s):  
Timothy Krantz ◽  
Brian Tufts
Keyword(s):  
Power Density ◽  
Fatigue Testing ◽  
Surface Hardness ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Surface Fatigue ◽  
Gear Steel ◽  
Single Tooth ◽  
Carburized Gear ◽  
Gear Steels

The power density of a gearbox is an important consideration for many applications and is especially important for gearboxes used on aircraft. One approach to improving power density of gearing is to improve the steel properties by design of the alloy. The alloy tested in this work was designed to be case-carburized with surface hardness of Rockwell C66 after hardening. Test gear performance was evaluated using surface fatigue tests and single-tooth bending fatigue tests. The performance of gears made from the new alloy was compared to the performance of gears made from two alloys currently used for aviation gearing. The new alloy exhibited significantly better performance in surface fatigue testing, demonstrating the value of the improved properties in the case layer. However, the alloy exhibited lesser performance in single-tooth bending fatigue testing. The fracture toughness of the tested gears was insufficient for use in aircraft applications as judged by the behavior exhibited during the single tooth bending tests. This study quantified the performance of the new alloy and has provided guidance for the design and development of next generation gear steels.

Analytical approximations to damaged gear tooth transmission-error contributions for gear-health monitoring

2015 ◽  
Vol 230 (7-8) ◽  
pp. 1157-1182 ◽  
Author(s):  
William D Mark
Keyword(s):  
Fatigue Damage ◽  
Gear Tooth ◽  
Transmission Error ◽  
Generic Model ◽  
Model Framework ◽  
Bending Fatigue ◽  
New Methods ◽  
Analytical Approximations ◽  
Significant Damage ◽  
Higher Harmonic

A generic model of transmission-error contributions arising from gear-tooth damage is developed. Damage is modeled as material removed from tooth-working-surfaces. Regions of modeled tooth damage are of limited size as in pitting damage or are extended to full working surfaces as in tooth-bending-fatigue damage. Results are computed for a wide variety of damage forms and formulated for any collection of teeth experiencing damage. Final results are expressed as transmission-error rotational-harmonic amplitudes arising from damage. Rotational-harmonic regions experiencing significant damage contributions from pitting/spalling damage and from tooth-bending-fatigue damage are delineated. Increases in higher harmonic-number amplitudes arising from transmission-error discontinuities are formulated. The overall model framework can be used to explain and interpret observed features of gear transmission-error spectra arising from gear-tooth damage and to develop new methods of detecting and assessing the severity of such damage.

Optimization of Tooth Bending Fatigue Characteristics of Spur Gear Pairs Using a Gear Dynamics-Based Approach

2015 ◽  
Author(s):  
Yalın Öztürk ◽  
Ender Ciğeroğlu ◽  
H. Nevzat Özgüven
Keyword(s):  
Fatigue Life ◽  
Gear Tooth ◽  
Spur Gear ◽  
Bending Fatigue ◽  
Gear Dynamics ◽  
Optimization Study ◽  
Fatigue Life Estimation ◽  
Fatigue Characteristics ◽  
Profile Optimization ◽  
Operational Range

A gear tooth profile optimization study is performed with the target being defined as the maximization of tooth bending fatigue life for a selected operational range, where the operating torque and speed ranges are defined along with their corresponding durations. For this purpose, a nonlinear lumped gear dynamics model is combined with the S/N curve of the gear material in order to estimate tooth bending fatigue life of the spur gear pair. The differences between the predicted lives of the optimally modified and non-modified gear pairs are presented based on example spur gear pairs. The proposed tooth bending fatigue life estimation is compared with the standard AGMA procedure.

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