Prediction of Spur Gear Mechanical Power Losses Using an EHL Model With Time-Varying Contact Parameters

2009 ◽  
Author(s):  
S. Li ◽  
A. Kahraman
Keyword(s):  
Power Loss ◽  
Normal Load ◽  
Elastohydrodynamic Lubrication ◽  
Spur Gear ◽  
Mechanical Power ◽  
Transient Pressure ◽  
Gear Mesh ◽  
Proposed Model ◽  
Time Variations ◽  
Contact Parameters

A physics-based model is proposed to predict load dependent (mechanical) power loss of spur gear pairs by using a specialized gear elastohydrodynamic lubrication (EHL) model. The EHL model includes time variations of all key contact parameters such as surface velocities, radii of curvature and normal load in their continuous forms such that a continuous analysis of a tooth contact from its root to tip can be performed. The EHL model has the capability to simulate any gear contacts represented by condition ranging from full EHL to mixed or boundary EHL conditions. Predicted transient pressure and film thickness distributions are used to determine the instantaneous as well as the overall mechanical power loss of the gear mesh. Correction factors are introduced to account for thermal effects. At the end, capabilities and accuracy of the proposed model are demonstrated by comparing its predictions to experimental data.

A Computational Study on the Mechanical Power Loss of a Spur Gear Pair Under the Thermal Tribo-Dynamic Condition

2015 ◽  
Author(s):  
Sheng Li
Keyword(s):  
Power Loss ◽  
Computational Study ◽  
Dynamic Condition ◽  
Elastohydrodynamic Lubrication ◽  
Static Condition ◽  
Spur Gear ◽  
Mechanical Power ◽  
Gear Pair ◽  
Gear Mesh ◽  
Six Degree Of Freedom

This study proposes a formulation for the description of the gear mesh mechanical power loss under the thermal tribodynamic condition. A six degree-of-freedom motion equation set that models the vibratory motions of a general spur gear pair is coupled with the governing equations for the description of the gear thermal mixed elastohydrodynamic lubrication to include the interactions between the gear dynamics and gear tribology disciplines in the modeling of the gear mesh mechanical power loss. The important role of the gear thermal tribo-dynamics in power loss is demonstrated by comparing the predictions of the proposed model to those under the thermal quasi-static condition, and the iso-thermal tribo-dynamic condition, respectively.

Frictional dynamic model predictions of FZG-A10 spur gear pairs considering profile errors

2020 ◽  
pp. 135065012096297
Author(s):  
Nabih Feki ◽  
Maroua Hammami ◽  
Olfa Ksentini ◽  
Mohamed Slim Abbes ◽  
Mohamed Haddar
Keyword(s):  
Dynamic Model ◽  
Coefficient Of Friction ◽  
Power Loss ◽  
Spur Gear ◽  
Operating Conditions ◽  
Time Dependent ◽  
Nonlinear Dynamic Model ◽  
Gear Mesh ◽  
Proposed Model ◽  
Profile Errors

In this work, a nonlinear dynamic model of an FZG-A10 spur gear was investigated by taking into account for the actual time-varying gear mesh stiffness and the frictional effects between meshing gear teeth to evaluate the influence of the dynamic effects on frictional gear power loss predictions. The equations of motion of the generalized translational-torsional coupled dynamic system derived from Lagrange principle was extended compared to authors’ previous work in order to account for time dependent coefficient of friction and profile errors. The dynamic response of spur gears, computed by an iterative implicit scheme of Newmark, is changed due to the presence of coefficient of friction and profile errors. A dynamic analysis was performed and the influence of frictional effect including tooth shape deviations, in particular, was scrutinized since a time-dependent coefficient of friction is deeply related to the gear surface roughness and all parameters dependent on gears error profiles are introduced in the proposed model. The predicted meshing gear power losses with constant and local friction coefficient were compared. The influence of constant and variable profile errors considered in the local coefficient of friction formulation was also studied and their corresponding root mean square (RMS) power loss was compared to the experimental results. The results using FZG A10 spur gear pairs running under several operating conditions (different loads and speeds) validate the superiority of the proposed model against previous similar models.

A Transient Mixed Elastohydrodynamic Lubrication Model for Helical Gear Contacts

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
A. S. Chimanpure ◽  
A. Kahraman ◽  
D. Talbot
Keyword(s):  
Power Loss ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Sensitivity Study ◽  
Helical Gear ◽  
Operating Conditions ◽  
Mechanical Power ◽  
Distribution Model ◽  
Rolling Velocity ◽  
Gear Mesh

Abstract In this study, a non-Newtonian, transient, isothermal, mixed elastohydrodynamic lubrication (EHL) model is proposed for helical gear contacts. The model accounts for nonelliptical contacts subject to spatially varying sliding and rolling velocity fields that are not aligned with any principal axis of the contact region, which is the case for helical gear contacts. The time-varying changes pertaining to key contact parameters and relative motion of roughness profiles on mating tooth surfaces are captured simultaneously to follow the contact from the root to the tip of a tooth while accounting for the transient effect due to relative motions of the roughness profiles. Actual tooth load distributions, contact kinematics, and compliances of helical gear contacts are provided to this model by an existing helical gear load distribution model. Measured three-dimensional roughness profiles covering the entire meshing zone are incorporated in the analyses to investigate its impact on the EHL conditions as well as mechanical power loss. Results of a parametric sensitivity study are presented to demonstrate the influence of operating conditions and surface roughness on the EHL behavior and the resultant gear mesh mechanical power loss of an example helical gear pair. The accuracy of the proposed mixed-EHL model is assessed by comparing the mechanical power loss predictions to available experimental results.

A Transient Mixed Elastohydrodynamic Lubrication Model for Spur Gear Pairs

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
S. Li ◽  
A. Kahraman
Keyword(s):  
Normal Load ◽  
Gear Tooth ◽  
Elastohydrodynamic Lubrication ◽  
Transient Behavior ◽  
Spur Gear ◽  
Numerical Approach ◽  
Operating Conditions ◽  
Proposed Model ◽  
Tangential Surface ◽  
Time Invariant

In this study, a transient, non-Newtonian, mixed elastohydrodynamic lubrication (EHL) model of involute spur gear tooth contacts is proposed. Unlike the contact between two cylindrical rollers, spur gear contacts experience a number of time-varying contact parameters including the normal load, radii of curvature, surface velocities, and slide-to-roll ratio. The proposed EHL model is designed to continuously follow the contact of a tooth pair from the root to the tip to capture the transient characteristics of lubricated spur gear contacts due to these parameter variations, instead of analyzing the contact at discrete positions assuming time-invariant parameters. The normal tooth force along the line of action is predicted by using a gear load distribution formulation and the contact radii and tangential surface velocities are computed from the kinematics and geometry of involute profiles. A unified numerical approach is adapted for handling asperity interaction in mixed EHL conditions. The differences between the transient and discrete EHL analyses are shown for a spur gear pair having smooth surfaces and different tooth profile modifications. The transient behavior predicted by the proposed model is found to be mainly due to the squeezing and pumping effects caused by sudden load changes. The lubrication behavior under rough conditions is also investigated at different operating conditions.

Effect of Design Parameters on Lubrication Behavior of Spur Gear Pairs

2017 ◽  
Author(s):  
Yanfang Liu ◽  
Qiang Liu ◽  
Peng Dong
Keyword(s):  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Spur Gear ◽  
Design Parameters ◽  
Curvature Radius ◽  
Gear Pair ◽  
Sliding Velocity ◽  
Rolling Velocity ◽  
Lubrication Performance ◽  
Meshing Process

An involute spur gear pair meshing model is firstly provided in this study to achieve relevant data such as rolling velocity, sliding velocity, curvature radius etc. These data are needed in a transient, Newtonian elastohydrodynamic lubrication (EHL) model which is provided later. Based on these two models, the behavior of an engaged spur gear pair during the meshing process is investigated under dynamic conditions, film thickness, pressure, friction coefficient etc. could be achieved through the models. Then, power loss under certain operating condition is calculated. Relationship between power loss and lubrication performance is also analyzed.

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.

Prediction of Spur Gear Mesh Stiffness Associated with the Tooth Corrosion

2015 ◽  
Vol 799-800 ◽  
pp. 570-575
Author(s):  
Zheng Min Qing Li ◽  
Qing Bin Zhao ◽  
Xiao Zhen Li
Keyword(s):  
Spur Gear ◽  
Mesh Stiffness ◽  
Gear Mesh ◽  
Gear Drive ◽  
Corrosion Effect ◽  
Proposed Model ◽  
Stiffness Model ◽  
The Stability ◽  
Gear Drives ◽  
Gear Mesh Stiffness

In this study, a mesh stiffness model of spur gear drives considering the tooth corrosion effect, which is based on Ishikawa model, is proposed. The fidelity of mesh stiffness based on the proposed model is checked by comparing the result with a benchmark result from the reference and the effect of the tooth corrosion on mesh stiffness is analyzed. The prediction indicates mesh stiffness is insensitive to the tooth corrosion, but this conclusion has a signification for assessing the stability of inherent properties of a spur gear drive when the tooth corrosion is produced.

Prediction of Mechanical Power Loss of Planet Gear Roller Bearings Under Combined Radial and Moment Loading

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
D. Talbot ◽  
S. Li ◽  
A. Kahraman
Keyword(s):  
Load Distribution ◽  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Planetary Gear ◽  
Mechanical Power ◽  
Distribution Model ◽  
Roller Bearings ◽  
Modeling Methodology ◽  
Force Moment ◽  
Planet Gear

A modeling methodology is proposed to predict load-dependent (mechanical) power loss of cylindrical roller bearings under combined radial and moment loading with focus on planetary gear set planet bearings. This methodology relies on two models. The first model is a bearing load distribution model to predict load intensities along rolling element contacts due to combined force–moment loading. This model takes into account planet bearing macrogeometry as well as micromodifications to the roller and race surfaces. The second model is an elastohydrodynamic lubrication (EHL) model employed to predict rolling power losses of bearing contacts with load intensities predicted by the load distribution model. The bearing mechanical power loss methodology is applied to bearings of an automotive planetary gear set to quantify the sensitivity of mechanical power loss to key bearing, lubrication and surface parameters as well as operating speed, load and temperature conditions.

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.

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