Analysis of Lubricating Performance for Involute Gear Based on Dynamic Loading Theory

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Shi H. Yuan ◽  
Hui L. Dong ◽  
Xue Y. Li
Keyword(s):  
Film Thickness ◽  
Dynamic Load ◽  
Elastohydrodynamic Lubrication ◽  
Helix Angle ◽  
Spur Gear ◽  
Face Width ◽  
Elastic Potential Energy ◽  
The Face ◽  
Squeeze Effect ◽  
The Impact

An integrated model for gear pair that combines the dynamic load with the mixed elastohydrodynamic lubrication (EHL) theory is proposed in this paper covering the film squeeze effect as well as the friction force generated from the rough surfaces. Comparisons between the two models of load which are, respectively, based on minimum elastic potential energy (MEPE) criterion and dynamic motion equations built up in this paper are discussed. The results show that at low speed the loads calculated by the two models are similar. However, with increasing speed, the load exhibits dynamic characteristics gradually and reaches the highest value at resonant speed. Besides, the effects of the helix angle and the lubricant viscosity are also analyzed. Increasing the ambient viscosity could intensify the film stiffness and viscous damping. Gear with larger helix angle could weaken the impact phenomenon at the shift points where one tooth-pair disengages. Moreover, it is symmetric with regard to the pressure and film thickness across the face width for spur gear. Differently, the pressure for helical gear has a higher value at the dedendum of pinion where the film becomes thinner. In addition, speeding up the pinion would generally result in higher dynamic load and film pressure but thicker film thickness.

Study of Transient Elastohydrodynamic Lubrication of Spur Gears under Impact Load

2011 ◽  
Vol 121-126 ◽  
pp. 3506-3509
Author(s):  
You Qiang Wang ◽  
Zhi Cheng He ◽  
Wei Su
Keyword(s):  
Film Thickness ◽  
Impact Load ◽  
Gear Tooth ◽  
Elastohydrodynamic Lubrication ◽  
Spur Gear ◽  
Time Varying ◽  
Spur Gears ◽  
Lubrication Film ◽  
The Impact ◽  
Contact Parameters

Spur gear contacts experience a number of time-varying contact parameters including the load, surface velocities, radii of curvature, and slide-to-roll ratio. It is very hard to obtain transient elastohydrodynamic lubrication (EHL) solution of spur gears. In this study, a transient EHL model of involute spur gear tooth contacts is proposed. A full transient EHL solution of involute spur gear under impact load is obtained by utilizing the multigrid technique. The influences of impact load on the EHL of spur gear are analyzed in the paper. The numerical results show that the approach impact load has strong transient influence on the oil film thickness and pressure distribution between contact zones. The impact load may lead to instantaneous lubrication film deterioration between contact teeth of involute spur gears.

A Theoretical Tribological Comparison Between Soft and Hard Coatings of Spur Gear Pairs

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Huaiju Liu ◽  
Caichao Zhu ◽  
Zhanjiang Wang ◽  
Ye Zhou ◽  
Yuanyuan Zhang
Keyword(s):  
Surface Deformation ◽  
Tribological Behavior ◽  
Elastohydrodynamic Lubrication ◽  
Spur Gear ◽  
Hard Coatings ◽  
Radius Of Curvature ◽  
Maximum Pressure ◽  
Gear Pair ◽  
The Coefficient Of Friction ◽  
Squeeze Effect

A thermal elastohydrodynamic lubrication (TEHL) model is developed for a coated spur gear pair to investigate the effect of soft coatings and hard coatings on the tribological behavior of such a gear pair during meshing. The coating properties, i.e., the ratio of the Young's modulus between the coating and the substrate, and the coating thickness, are represented in the calculation of the elastic deformation. Discrete convolution, fast Fourier transform (DC-FFT) is utilized for the fast calculation of the surface deformation. The variation of the radius of curvature, the rolling speed, the slide-to-roll ratio, and the tooth load along the line of action (LOA) during meshing is taken into account and the transient squeeze effect is considered in the Reynolds equation. Energy equations of the solids and the oil film are derived. The temperature field and the pressure field are solved iteratively. The tribological behavior is evaluated in terms of the minimum film thickness, the maximum pressure, the temperature rise, the coefficient of friction, and the frictional power loss of the tooth contact during meshing. The results show discrepancies between the soft coating results and hard coating results.

Investigation of the Hertzian Stress Distribution on the Surface of the Straight Bevel Gear

2013 ◽  
Vol 307 ◽  
pp. 304-307 ◽  
Author(s):  
Aref Bahramighahnavieh ◽  
Peiman Mosaddegh ◽  
Saleh Akbarzadeh
Keyword(s):  
Stress Distribution ◽  
Spur Gear ◽  
Bevel Gear ◽  
Gear Teeth ◽  
Straight Bevel Gear ◽  
Face Width ◽  
The Face ◽  
Simulation Results ◽  
Abaqus Software ◽  
Good Agreement

In this paper, a model has been developed for calculating the Hertzian stress distribution of straight bevel gear. One pair of straight bevel gear teeth replaced with multiple pairs of spur gear teeth by using Tredgold approximation. The transmitted load and radii of curvature are evaluated and used to determine the stress distribution. The results show that these stresses are constant along the face width of tooth. Moreover, the magnitude of theses stresses are in good agreement with the simulation results using commercial ABAQUS software

Effect of oil starvation on the isothermal impact problem

2017 ◽  
Vol 232 (10) ◽  
pp. 1332-1339
Author(s):  
Duohuan Wu ◽  
Jing Wang ◽  
Peiran Yang ◽  
Ton Lubrecht
Keyword(s):  
Film Thickness ◽  
Pressure Gradient ◽  
Thickness Distribution ◽  
Elastohydrodynamic Lubrication ◽  
Maximum Pressure ◽  
Numerical Techniques ◽  
Minimum Film Thickness ◽  
The Impact ◽  
Impact Motion ◽  
Impact Problem

In this study, the effect of oil starvation on isothermal elastohydrodynamic lubrication of an impact motion is explored with the aid of numerical techniques. During the impact process, on comparison with the fully lubricated results, the pressure and film thickness are much lower and the entrapped film shape does not happen. The rebound is delayed by the oil starvation assumption. During the rebound process, a periphery entrapment is seen in the starved film thickness distribution. Under the starved condition, the maximum pressure gradient is higher. The central film thickness and minimum film thickness exhibit different variations compared with the results by fully flooded assumption.

Investigation on the effect of coating properties on lubrication of a coated spur gear pair

2017 ◽  
Vol 232 (3) ◽  
pp. 277-290 ◽  
Author(s):  
Huaiju Liu ◽  
Caichao Zhu ◽  
Zhanjiang Wang ◽  
Xiangyang Xu ◽  
Jinyuan Tang
Keyword(s):  
Surface Displacement ◽  
Elastohydrodynamic Lubrication ◽  
Spur Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Transform Method ◽  
Influence Coefficients ◽  
Stress Components ◽  
Squeeze Effect ◽  
Energy Equations

A thermal elastohydrodynamic lubrication model is proposed for a coated gear pair in which the influence coefficients for the elastic deformation and the subsurface stress components are obtained through the frequency response functions. The generalized Reynolds equation is utilized to represent the non-Newtonian effect. Energy equations of the contacting solids and the oil film are derived and solved based upon the marching method. The discrete convolute, fast Fourier transform method is used for fast calculation of the tooth surface displacement and the stress components underneath the surface. Variations of the slide-to-roll ratio, rolling speed, and the tooth load during gear meshing are considered and the film squeeze effect is taken into account. Effects of the coating thickness on the tribological performance, i.e. the film thickness, the pressure, the frictional behavior as well as the stress components are investigated under both the smooth and rough surface assumptions. Effects of the root mean square value of the tooth surface roughness on the pressure and stresses are discussed.

Contact Damping and Stiffness Calculation Model for Rough Surface Considering Lubrication in Involute Spur Gear

2021 ◽  
Author(s):  
Gong Cheng ◽  
Ke Xiao ◽  
Jiaxu Wang
Keyword(s):  
Film Thickness ◽  
Contact Stiffness ◽  
Elastohydrodynamic Lubrication ◽  
Spur Gear ◽  
Calculation Model ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Crucial Point ◽  
Normal Deformation ◽  
Oil Film

The contact properties of an interface are crucial to the performance of equipment, and it is necessary to study the contact damping and contact stiffness, especially in the case of mixed lubrication. A calculation model for contact damping and contact stiffness considering lubrication was proposed on the basis of the KE contact model and mixed elastohydrodynamic lubrication theory. Both the damping and the stiffness were composed of the oil film portion and the asperity contact portion. Since the damping and the stiffness of oil film mainly depended on the film thickness and the pressure, which can be obtained with the mixed lubrication model, another crucial point was to figure out the contribution of asperity contact. Ignoring the effect of the tangential deformation, the stiffness and the load determined with the normal deformation of the asperity were obtained. Then, the contact damping and the contact stiffness considering lubrication could be derived. Finally, the model was applied to the study of contact damping and stiffness of the involute spur gear.

Frictional Contact Stress Analysis of Spur Gear by Using Finite Element Method

2015 ◽  
Vol 772 ◽  
pp. 159-163 ◽  
Author(s):  
Muhammad Farhan ◽  
Saravanan Karuppanan ◽  
Santosh S. Patil
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Contact Stress ◽  
Frictional Coefficient ◽  
Spur Gear ◽  
Gear Teeth ◽  
Face Width ◽  
The Face ◽  
Stress Result ◽  
Element Method

Spur gear is used to transfer rotary motion between parallel shafts. The simplicity in its design is one of the advantages of the spur gear. However higher frictional force that is accumulated on the gear teeth will influence the spur gear performance. Many previous papers elaborated extensively on the contact stress in the spur gear but few of them gave the details on how friction affects the gear teeth. There are insufficient frictional effect data in the gear and thus should be regarded as an important research parameter. In this paper, the contact stress of spur gear has been evaluated with and without friction by employing the Hertz theory, AGMA standard and finite element method (FEM). The frictionless contact stress result has been validated with both the theoretical methods with minimum deviation. Frictional coefficient range of 0.0 to 0.3 was selected and the corresponding contact stress is directly proportional to the friction coefficient. The work also involves the variation of face width of the gear set under the influence of friction. The contact stress of spur gear was found to be inversely proportional to the face width.

A Methodology to Experimentally Investigate the Impact of Wobble Errors on the Contact Pattern and Static Transmission Error of Helical Gear Pairs

2019 ◽  
Author(s):  
Michael Benatar ◽  
Michael Handschuh ◽  
Ahmet Kahraman ◽  
David Talbot
Keyword(s):  
Transmission Error ◽  
Helical Gear ◽  
Experimental Results ◽  
Gear Pair ◽  
Contact Pattern ◽  
Gear Mesh ◽  
Face Width ◽  
The Face ◽  
Static Transmission Error ◽  
The Impact

Abstract For a gear pair, both the contact pattern and the transmission error (TE) significantly impact durability and fatigue life. Design and manufacturing processes are often aimed at improving the contact pattern and reducing the overall TE. Other errors, such as runout and wobble, are often induced during the installation of power transmission systems, and they can alter the contact pattern and TE of an otherwise well-designed gear pair. This study provides a methodology to experimentally investigate the impact of wobble errors on the contact pattern and static transmission error (STE) of helical gears. It first provides a description of the modifications to an existing test machine. Next, it describes the gear specifications, preliminary testing matrix, data acquisition and processing procedure, as well as the experimental results obtained with regards to both the contact pattern and STE. The following are observed while describing the experimental results. For a test with no wobble and no runout, the contact pattern remains the same at every rotational position. However, by introducing even a small amount of wobble, the contact will shift from one side of the face width of the gear to the opposite side of the face width of the gear within one revolution. Introduction of wobble may increase the STE and sideband activity around gear mesh harmonics, especially as torque increases. Yet the modest increases in STE and sideband activity seen with the introduction of wobble are not enough to make definitive conclusions. The feasibility of the modified test setup has been demonstrated, and preliminary results have been presented. However, additional data collection should be completed in order to study the impact of runout and wobble on both spur and helical gear pairs with various microgeometry modifications and manufacturing errors.

Effect of Impact Load on Transient Elastohydrodynamic Lubrication of Spur Gears

2011 ◽  
Vol 317-319 ◽  
pp. 548-551
Author(s):  
You Qiang Wang ◽  
Zhi Cheng He
Keyword(s):  
Film Thickness ◽  
Impact Load ◽  
Gear Tooth ◽  
Elastohydrodynamic Lubrication ◽  
Tooth Surface ◽  
Maximum Pressure ◽  
Spur Gears ◽  
Load Spectrum ◽  
Minimum Film Thickness ◽  
The Impact

A full transient elastohydrodynamic lubrication(EHL) solution of involute spur gears is obtained under impact load based on the multi-grid (MG) method for solving the pressures, the multi-level multi-integration (MLMI) approach for evaluating the elastic deformations, which takes into account the variation of equivalent curvature , entertainment velocity and load on time along the line of action, the gear tooth surface is assumed to be smooth. The influences of impact load spectrum and the approach impact load when the teeth come into action on the EHL pressure and film thickness are analyzed in the paper. The results show that the approach impact load can strongly influence the approach point maximum pressure and minimum film thickness. The impact load can lead to instantaneous lubrication film deterioration between contact teeth of involute spur gears. The maximum pressure and the minimum film thickness all occur in the vicinity of approach point immediately after the impact load was feed. The approach impact load is seriously harmful to the gear lubrication.

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