A Fatigue Model for Spur Gear Contacts Operating Under Mixed Elastohydrodynamic Lubrication Conditions

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
S. Li ◽  
A. Kahraman ◽  
M. Klein
Keyword(s):  
Crack Nucleation ◽  
Surface Condition ◽  
Elastohydrodynamic Lubrication ◽  
Spur Gear ◽  
Mixed Lubrication ◽  
Distribution Model ◽  
Tooth Surface ◽  
Stress Concentrations ◽  
Fatigue Model ◽  
Lubrication Conditions

This paper presents a model to predict the crack formation fatigue lives of spur gear contacts operating under mixed lubrication conditions where surface roughnesses introduce intermittent metal-to-metal contacts and severe stress concentrations. The proposed model consists of several submodels, including (i) a gear load distribution model to determine the normal tooth force distribution along the tooth surface, incorporating any profile modifications and manufacturing deviations, (ii) a mixed elastohydrodynamic lubrication model customized to handle transient contact conditions of gears, (iii) a stress formulation that assumes the plane strain condition to compute the transient elastic stress fields on and below the tooth surface induced by the mixed lubrication surface pressure and shear stress distributions, and (iv) a multi-axial fatigue model to predict the crack nucleation life distribution. The proposed spur gear fatigue model is used to simulate the contacts of gear pairs having different surface roughness amplitudes. The predictions are compared to the measured gear fatigue stress-life data for each surface condition to assess the model accuracy in the prediction of the crack nucleation fatigue lives as well as the location of the critical failure sites.

A Fatigue Model for Spur Gear Contacts Operating Under Mixed Elastohydrodynamic Lubrication Conditions

2011 ◽  
Author(s):  
Sheng Li ◽  
Ahmet Kahraman ◽  
Mark Klein
Keyword(s):  
Crack Nucleation ◽  
Surface Condition ◽  
Elastohydrodynamic Lubrication ◽  
Spur Gear ◽  
Mixed Lubrication ◽  
Distribution Model ◽  
Tooth Surface ◽  
Stress Concentrations ◽  
Fatigue Model ◽  
Lubrication Conditions

This paper presents a model to predict the crack formation fatigue lives of spur gear contacts operating under mixed lubrication conditions where surface roughnesses introduce intermittent metal-to-metal contacts and severe stress concentrations. The proposed model consists of several submodels including (i) a gear load distribution model to determine the normal tooth force distribution along the tooth profile, incorporating any profile modifications and manufacturing deviations, (ii) a mixed elastohydrodynamic lubrication model customized to handle transient contact conditions of gears, (iii) a stress formulation that assumes the plane strain condition to compute the transient elastic stress fields on and below the tooth surface induced by the mixed lubrication surface pressure and shear stress distributions, and (iv) a multi-axial fatigue model to predict the crack nucleation life distribution. The proposed spur gear fatigue model is used to simulate the contacts of gear pairs having different surface roughness amplitudes. The predictions are compared to the measured gear fatigue Stress-Life data for each surface condition to assess the model accuracy in predicting the crack nucleation fatigue lives as well as the location of the critical failure sites.

The Effect of Spur Gear Tribo-Dynamic Response on Pitting Crack Nucleation

2017 ◽  
Author(s):  
Sheng Li ◽  
Anusha Anisetti
Keyword(s):  
Crack Nucleation ◽  
Axial Stress ◽  
Contact Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Normal Pressure ◽  
Spur Gear ◽  
Dynamics Simulation ◽  
Dynamic Surface ◽  
Fatigue Crack Nucleation ◽  
Gear Mesh

This study investigates the role of the tribo-dynamic behavior in the contact fatigue crack nucleation for spur gears. To describe this fatigue phenomenon, a six-degree-of-freedom (DOF) lumped parameter dynamics formulation is coupled with a set of mixed elastohydrodynamic lubrication (EHL) governing equations. The former provides the dynamic tooth force to the EHL analysis, and the latter yields the gear mesh damping as well as the friction excitations that are required in the gear dynamics simulation. The converged tribo-dynamic surface normal pressure and tangential shear are then used to determine the multi-axial stress fields using the potential theory based closed-form stress formulation for half space. Lastly, the stress means and amplitudes are implemented in a multi-axial fatigue criterion to assess the fatigue damage.

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.

Effects of Speed on Scuffing in Mixed Lubrication

1994 ◽  
Vol 208 (4) ◽  
pp. 269-279 ◽  
Author(s):  
D A Kelly ◽  
C G Barnes
Keyword(s):  
Thermal Model ◽  
Elastohydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Engineering Practice ◽  
General Criterion ◽  
Sliding Direction ◽  
Lubrication Regime ◽  
Surface Finishes ◽  
Mixed Lubrication Regime ◽  
Lubrication Conditions

Theories of failure of elastohydrodynamic lubrication are briefly reviewed, but none that relate to scuffing per se and no general criterion that accounts for the sensitivity of scuffing to rolling as well as sliding speed are found. A theoretical investigation of micro-EHL by Baglin, for surface finishes with a lay parallel to the sliding direction, predicts boundaries in the operating condition domain to a regime of mixed lubrication in which little elastic deformation of asperities by micro-EHL is expected. A new thermal model incorporating salient features of scuffing in mixed lubrication conditions is described. It is shown to give the form of a boundary in the sliding/rolling speed domain above which localized temperatures close to melting may be expected and below which lower temperatures suggest running-in without scuffing may be expected. Results of scuffing tests on circumferentially ground discs, at sliding and rolling speeds in the range 3-10 m/s, are reported and shown for surfaces with a distinguishable mainscale wavelength in their topography, (a) to provide further support for the location of the boundaries to the mixed lubrication regime in the operating domain predicted by Baglin and (b) to match the form of the thermal model in the speed domain. Implications for engineering practice are briefly discussed.

A fatigue model for spiral bevel gears under mixed elastohydrodynamic lubrication conditions

2021 ◽  
Author(s):  
Wei Cao ◽  
Wei Pu ◽  
Di Wang ◽  
Yu Yang ◽  
Xuanqiu Li ◽  
...  
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Fatigue Model ◽  
Spiral Bevel ◽  
Lubrication Conditions

scholarly journals Contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions

Friction ◽  
2021 ◽  
Author(s):  
Zongzheng Wang ◽  
Wei Pu ◽  
Xin Pei ◽  
Wei Cao
Keyword(s):  
Contact Stiffness ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Dry Contact ◽  
Spiral Bevel ◽  
Stiffness And Damping ◽  
Lubrication Conditions ◽  
Film Lubrication

AbstractExisting studies primarily focus on stiffness and damping under full-film lubrication or dry contact conditions. However, most lubricated transmission components operate in the mixed lubrication region, indicating that both the asperity contact and film lubrication exist on the rubbing surfaces. Herein, a novel method is proposed to evaluate the time-varying contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions. This method is sufficiently robust for addressing any mixed lubrication state regardless of the severity of the asperity contact. Based on this method, the transient mixed contact stiffness and damping of spiral bevel gears are investigated systematically. The results show a significant difference between the transient mixed contact stiffness and damping and the results from Hertz (dry) contact. In addition, the roughness significantly changes the contact stiffness and damping, indicating the importance of film lubrication and asperity contact. The transient mixed contact stiffness and damping change significantly along the meshing path from an engaging-in to an engaging-out point, and both of them are affected by the applied torque and rotational speed. In addition, the middle contact path is recommended because of its comprehensive high stiffness and damping, which maintained the stability of spiral bevel gear transmission.

Modeling of surface roughness in a novel magnetorheological gear profile finishing process

2020 ◽  
pp. 095440622097826
Author(s):  
Ravi Datt Yadav ◽  
Anant Kumar Singh ◽  
Kunal Arora
Keyword(s):  
Surface Roughness ◽  
Gear Tooth ◽  
Surface Characteristics ◽  
Spur Gear ◽  
Tooth Profile ◽  
Tooth Surface ◽  
Magnetic Flux Density ◽  
Element Analysis ◽  
Finishing Process ◽  
Gear Profile

Fine finishing of spur gears reduces the vibrations and noise and upsurges the service life of two mating gears. A new magnetorheological gear profile finishing (MRGPF) process is utilized for the fine finishing of spur gear teeth profile surfaces. In the present study, the development of a theoretical mathematical model for the prediction of change in surface roughness during the MRGPF process is done. The present MRGPF is a controllable process with the magnitude of the magnetic field, therefore, the effect of magnetic flux density (MFD) on the gear tooth profile has been analyzed using an analytical approach. Theoretically calculated MFD is validated experimentally and with the finite element analysis. To understand the finishing process mechanism, the different forces acting on the gear surface has been investigated. For the validation of the present roughness model, three sets of finishing cycle experimentations have been performed on the spur gear profile by the MRGPF process. The surface roughness of the spur gear tooth surface after experimentation was measured using Mitutoyo SJ-400 surftest and is equated with the values of theoretically calculated surface roughness. The results show the close agreement which ranges from −7.69% to 2.85% for the same number of finishing cycles. To study the surface characteristics of the finished spur gear tooth profile surface, scanning electron microscopy is used. The present developed theoretical model for surface roughness during the MRGPF process predicts the finishing performance with cycle time, improvement in the surface quality, and functional application of the gears.

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