Tooth Surface Fatigue Research Articles

Reliability analysis of thin-walled ring gear based on tooth surface fatigue and wear

Reliability analysis of thin-walled ring gear based on tooth surface fatigue and wear

Investigation on the influence of spalling defects on the dynamic performance of planetary gear sets with sliding friction

With the lubrication conditions deteriorating, sliding friction appears and affects the dynamic performance of planetary gear sets significantly. Furthermore, sliding friction can accelerate tooth surface fatigue and consequently cause many kinds of tooth failures. Spalling defect is a typical tooth failure of planetary gear sets. The influence of the spalling defect on the dynamic performance of planetary gear sets remains unknown when sliding friction is considered. In this paper, a dynamic model is proposed to investigate the dynamics of planetary gear sets with the spalling defect and sliding friction. The dynamic model includes the effect of the time-varying mesh stiffness, mesh damping, sliding friction forces and torques. A planetary gear set with three planet gears is taken as an example to analyze the effect of the spalling defect under sliding friction. Through the simulation analysis, it can be found that the spalling defect and sliding friction have remarkable influence on the dynamic responses of the planetary gear set. Finally, the dynamic model is validated by the experiments. This research establishes the theoretical basis for the diagnosis of the spalling defect of the planetary gear set with sliding friction.

New approach for gear mesh stiffness evaluation of spur gears with surface defects

Gear tooth surface fatigue is one of the most common failure modes of gears. Surface fatigue manifests on two principle phenomena, namely spalling and pitting. Spalls are localized cavities on the teeth surface with relatively important depths, whereas pits are distributed cavities on all the teeth surface with small depths. Generally, spalls and pits appear with nonuniform shapes, making their modelization difficult for researchers. Therefore, common methods assume specific geometries (rectangles, triangles, circles, etc.) to consider surface defects on the gear mesh stiffness evaluation process. In this paper, a new method has been proposed to accurately calculate the gear mesh stiffness of spur gears with surface defects based on the potential energy method. A double discretization of the tooth surface was performed to consider defect depth variation in both width and length directions of the gear tooth. A contact detection algorithm is developed to detect actual contact points during meshing process. Simulation results showed that the deformation of the gear mesh stiffness due to irregular shaped spalls and pits was completely different to those of regular shape and depends on the defect severity. In addition, results showed that the spall size and position have an impact on the final deformation of the gear mesh stiffness. The proposed method allowed remedying to multiple problems exposed by researchers in modeling gear mesh stiffness of gears with tooth surface defects.

Tooth surface fatigue strength analysis of hyper conical gear focusing on the internal crack growth

Tooth surface fatigue strength analysis of hyper conical gear focusing on the internal crack growth

Study on simulation for the tooth surface fatigue strength analysis of conical gear

Study on simulation for the tooth surface fatigue strength analysis of conical gear

Influence of Variability in Helix Deviation between Gear Teeth on Tooth Surface Strength of Transmission Gears

To predict precisely the tooth surface strength of transmission gears has been a very important issue in developing a new vehicle-transmission with high reliability, because failures such as pitting or spalling on the tooth surface have recently determined the gear life. Mass produced transmission gears have some unevenness in helix deviation between the teeth, which is caused by runout of the cutter arbor, heat treatment distortion, assembly errors, etc. It is important to clarify quantitatively the influence of the variability in helix deviation on the tooth surface strength of gears; however, no report on the subject has been published. In this study, gear surface fatigue endurance tests were carried out using carburized gears with five types of uneven helix deviation between the teeth. The results were examined, and the author introduces a new parameter, “Modified Hertzian pressure” that is based on cumulative fatigue damage rule on the tooth surface and the variation of Hertzian pressure during gear mesh. It is demonstrated that tooth surface fatigue life can be estimated quantitatively using this parameter. Based on the information obtained, the influence of the variability in helix deviation on the tooth surface strength is discussed.

Malfunction Analysis of the NC Machine Tool and its Vibration Model

The means of classification of the NC machine tool malfunctions is the key basis on detecting malfunctions and processing malfunctions` s signal. By defining malfunction mechanism and malfunction mode, a series of new classifications are presented. According to malfunction mechanism, mechanical malfunction are damage malfunction, lubrication malfunction, and fit malfunction. According to malfunction mode, the noise malfunction can be classified as vibration malfunction mode, the heating malfunction can be classified as heating malfunction mode, and the bad motion malfunction can be classified as deformation malfunction mode. Conclusion is that damage malfunction of gear and bearing malfunction is the most frequent malfunction whose performance formation is noise. Another conclusion is that tooth surface fatigue is the familiar malfunction, and bearing malfunction is mainly caused by surface peeling. Based on these conclusions, the vibration model of the mechanical failure is established, which lays a foundation for dealing with the follow-up signal.

Influence of Tooth Profile and Helix Deviation on Tooth Surface Strength of Carburized Helical Gears.

Because the life of power transmission gears has come to be greatly affected by the tooth surface strength, it is an important problem to clarify the influence of tooth profile and helix deviation on the tooth surface strength of carburized helical gears in a practical design. In this research, first, the experiments were carried out to measure the tooth surface strength using the test gears with six kinds of different tooth surface deviation. Next, this experimental result was arranged as S-N diagram by using Hertzian contact stress calculated in consideration of the tooth surface deviation. The influence of the tooth surface deviation on the tooth surface fatigue life was quantitatively shown by the empirical formula. Using the obtained result, the influence which the kind and the amount of the tooth profile and helix deviation exerted on the tooth surface fatigue life was considered. In addition, the effect of crowning was discussed.

212 コニカルギヤの歯面疲労強度に関する研究(OS1-4 伝動装置の基礎と応用)

212 コニカルギヤの歯面疲労強度に関する研究(OS1-4 伝動装置の基礎と応用)

Computerized Analysis of Gear Meshing Based on Coordinate Measurement Data

A mathematical model is proposed for the reconstruction of gear tooth surface features based on the manufacturing process deviations measured with the help of a gear inspection (or coordinate measurement) machine. The model is extended to facilitate the computer simulation of meshing between the measured gear and a theoretical master gear, or between two measured gears. This would allow one to predict the transmission errors and bearing contact which are otherwise only possible to investigate using the combination of single-flank testing and a time-consuming work-in and examination procedure. The developed model is applied to the determination of tooth-to-tooth transmission errors of parallel-axis gears and can also be utilized to determine bearing contact and contact stresses and be useful in tooth surface fatigue life calculations.

Trial production of a specific sliding varying type contact roller testing machine and its characteristics.

In the case of a general roller testing machine which is- employed at researching the tooth surface fatigue of gear materials, the specific sliding on test roller is constant during a rotation of the test roller. In this report, a new roller testing machine which can give a continuously varying specific sliding to the test roller was developed using an eccentric gear mechanism and its characteristics were elucidated. In this new type machine, the specific sliding of the test roller changes continuously in the ranges of -125% to 0%, -50% to +33% and 0% to +56 %. The minimum oil film thichness between the test rollers changes during a rotation of the roller with the change of circumferential velocity ratio of the roller pair. The change of the tangential force between the rollers during a rotation of the roller depends upon the changes of the normal force and the friction coefficient between the rollers.

Study on the Effect of Tooth Fatigue on Dynamic Performance of Gear Pair : 1st Report In the case of induction-hardened Chromium Molybdenum Steel Gears

In order to elucidate the failure mode, load carrying capacity and relation between tooth profile change and dynamic performance in fatigue process of a surface hardened gear, operational fatigue tests were performed using induction-hardened chromium molybdenum steel gears, The failure mode in these experiments was pitting or tooth breakage due to tooth surface fatigue except one example in which tooth breakage occurred at tooth fillet. Tooth root strain, mode in tooth stress frequency distribution, noise and vibration increased as the tooth profile was degraded, and it was also made clear experimentally that the failure prediction by sound level change was difficult for the tooth breakage at tooth fillet and tooth breakage due to spalling.

Endurance and Failure Characteristics of Modified Vasco X-2, CBS 600 and AISI 9310 Spur Gears

Gear endurance tests and rolling-element fatigue tests were conducted to compare the performance of spur gears made from AISI 9310, CBS 600 and modified Vasco X-2 and to compare the pitting fatigue lives of these three materials. Gears manufactured from CBS 600 exhibited lives longer than those manufactured from AISI 9310. However, rolling-element fatigue tests resulted in statistically equivalent lives. Modified Vasco X-2 exhibited statistically equivalent lives to AISI 9310. CBS 600 and modified Vasco X-2 gears exhibited the potential tooth fracture occurring at a tooth surface fatigue pit. Case carburization of all gear surfaces for the modified Vasco X-2 gears results in fracture at the tips of the gears.

The Effect of Lubricants on Gear Tooth Surface Fatigue

This paper presents some of the results of a recent investigation on the effect of lubricants on gear tooth surface fatigue (pitting). The work described comprises the development of a laboratory test procedure for exploratory purposes, and the determination of the performance of a number of lubricants using this procedure. It was found that bulk lubricant viscosity, as measured by the conventional viscometric method, did not have a predominant effect on gear tooth surface fatigue. Examination of the development of scuffing and pitting on the gear teeth indicates that the initial incidence of scuffing and the initial incidence of pitting were unrelated. It was further noted that as pitting became advanced, severe scuffing of the pitted teeth would almost invariably result. On the other hand, there was no evidence that severe scuffing would lead to gear tooth pitting. Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Toronto, Canada, October, 1957.