Calculation of Gear Meshing Stiffness Considering Lubrication

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Gong Cheng ◽  
Ke Xiao ◽  
Jiaxu Wang ◽  
Wei Pu ◽  
Yanfeng Han
Keyword(s):  
Rough Surface ◽  
Calculation Method ◽  
Contact Stiffness ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Meshing Stiffness ◽  
Roughness Amplitude ◽  
Meshing Process

Abstract Gear meshing stiffness is the key parameter to study the gear dynamic performance. However, the study on the calculation of gear meshing stiffness considering lubrication, especially mixed lubrication, is still insufficient. Based on the three-dimensional linear contact mixed elastohydrodynamic lubrication model and the contact stiffness calculation method of rough surface, a method for calculating the gear meshing stiffness under mixed lubrication is proposed in this paper. According to the proposed calculation method, the effects of speed, external load, and roughness amplitude on gear meshing stiffness are further explored. The method can take into account the real rough surface topography and lubrication in the meshing process, so it may be more advantageous than the conventional method to some extent.

Plasto-Elastohydrodynamic Lubrication in Point Contacts for Surfaces With Three-Dimensional Sinusoidal Waviness and Real Machined Roughness

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Tao He ◽  
Ning Ren ◽  
Dong Zhu ◽  
Jiaxu Wang
Keyword(s):  
Plastic Deformation ◽  
Rough Surface ◽  
Mechanical Design ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Von Mises Stress ◽  
Asperity Contacts ◽  
Lubrication Characteristics ◽  
Von Mises

Efficiency and durability are among the top concerns in mechanical design to minimize environmental impact and conserve natural resources while fulfilling performance requirements. Today mechanical systems are more compact, lightweight, and transmit more power than ever before, which imposes great challenges to designers. Under the circumstances, some simplified analyses may no longer be satisfactory, and in-depth studies on mixed lubrication characteristics, taking into account the effects of 3D surface roughness and possible plastic deformation, are certainly needed. In this paper, the recently developed plasto-elastohydrodynamic lubrication (PEHL) model is employed, and numerous cases with both sinusoidal waviness and real machined roughness are analyzed. It is observed that plastic deformation may occur due to localized high pressure peaks caused by the rough surface asperity contacts, even though the external load is still considerably below the critical load determined at the onset of plastic deformation in the corresponding smooth surface contact. It is also found, based on a series of cases analyzed, that the roughness height, wavelength, material hardening property, and operating conditions may all have significant influences on the PEHL performance, subsurface von Mises stress field, residual stresses, and plastic strains. Generally, the presence of plastic deformation may significantly reduce some of the pressure spikes and peak values of subsurface stresses and make the load support more evenly distributed among all the rough surface asperities in contact.

scholarly journals Theoretical and Experimental Study on Normal Contact Stiffness of Joint Surfaces with Surface Texturing

2020 ◽  
Author(s):  
Chao-Chao Yin ◽  
Hai-Hong Huang ◽  
Dan Zhou ◽  
Zhi-Feng Liu
Keyword(s):  
Rough Surface ◽  
Contact Stiffness ◽  
Fractal Theory ◽  
Surface Texturing ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Normal Contact ◽  
Joint Surfaces ◽  
Theoretical Predictions ◽  
Normal Contact Stiffness

Abstract Effects of surface texturing on the normal contact stiffness of joint surfaces had been investigated by experiments in many previous researches; however, there are relatively few theoretical models in this regard. The rough surface with surface texturing can be divided into two parts: the textured zone and the remaining zone, and their theoretical models are established respectively in this research. For the textured zone, the texture is modeled theoretically based on the three-dimensional topographic data obtained via a 3D-CCMP1 type laser profilometer from TRIMOS. For the remaining zone, the model of normal contact stiffness is established based on the fractal theory for the surface topography description and elastic-plastic deformation of surface asperities, and the structure function method is used to calculate the fractal dimension of rough surface profiles. In the experiment, the normal contact stiffness of specimens is obtained under different normal loads, and the test results are compared with the theoretical predictions. The result shows that the predictions of proposed theoretical model are in good agreement with the experimental data. For the joint surfaces with Sa>2.69 μm, the normal contact stiffness can be effectively increased through proper surface texturing.

scholarly journals Effect of Detuning of Clamping Force of Tie Rods on Dynamic Performance of Rod-Fastened Jeffcott Rotor

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Haoliang Xu ◽  
Lihua Yang ◽  
Tengfei Xu ◽  
Yao Wu
Keyword(s):  
Natural Frequency ◽  
Rough Surface ◽  
Contact Stiffness ◽  
Dynamic Performance ◽  
Flexural Stiffness ◽  
Clamping Force ◽  
Term Operation ◽  
Analysis And Design ◽  
Jeffcott Rotor ◽  
Tie Rods

In view of the advantages of lightweight, high strength, easy cooling, and easy assembly, the rod-fastened rotor is widely used in the aeroengine and heavy gas turbine. However, because of assembly, stress relaxation, material creep, and other reasons, the clamping force of the tie rods will be out of tune during the long-term operation of the rotor. The detuning of the clamping force of the tie rods not only affects the contact stiffness of the contact interface but also causes the rod-fastened rotor with a certain residual shaft bow, which will affect the dynamic characteristics of the rod-fastened rotor. Based on the statistical model of rough surface contact (GW contact model), this paper presents a method to calculate the equivalent flexural stiffness of rough surface considering the detuning of the clamping force of the tie rods and gives the calculation method of the residual shaft bow deformation of the rod-fastened Jeffcott rotor with detuning of the tie rods. The effect of the preload, the rate of detuning of the tie rods, the number of detuning tie rods on the natural frequency, and the response of residual shaft bow of the rod-fastened Jeffcott rotor at a certain speed are investigated. The results show that the detuning of the tie rods makes the flexural stiffness of the rotor inconsistent along with two main stiffness directions of the rotor, which makes the natural frequency of the rotor divided into two. The negative detuning of the tie rods decreases the natural frequency of the rotor, while the positive detuning of the tie rods increases the natural frequency of the rotor. The smaller preload or the larger rate of detuning of the tie rods makes the detuning of the tie rods have a greater influence on the natural frequency of the rotor. These results will provide a theoretical reference for the dynamic analysis and design of the rod-fastened rotor.

Point Contact EHL Based on Optically Measured Three-Dimensional Rough Surfaces

1997 ◽  
Vol 119 (3) ◽  
pp. 375-384 ◽  
Author(s):  
Dong Zhu ◽  
Xiaolan Ai
Keyword(s):  
Rough Surface ◽  
Rough Surfaces ◽  
Three Dimensional ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Peak Height ◽  
Machining Process ◽  
Maximum Pressure ◽  
Pressure Peak ◽  
Surface Profiles

This paper presents a numerical solution for the elastohydrodynamic lubrication in point contacts, using optically measured three-dimensional rough surface profiles as input data. The multi-grid computer program originally developed by Ai and Cheng (1993, 1994) is modified, so that both contacting surfaces can be three-dimensional measured rough surfaces moving at different velocities. Many different engineering surfaces are measured and analyzed in the present study, demonstrating that the numerical analysis is practical for real surfaces of bearings, cams, gears and other components, as long as a significant EHL film still exists. In addition, discussions are given in this paper for the effects of three-dimensional rough surface topography, which is related to machining process. It appears that, for the circular contact cases analyzed, surface roughness texture and orientation do not have a significant effect on the average film thickness, but they do affect the maximum pressure peak height and asperity deformation in the contact zone considerably.

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.

Modeling and Analysis of Mixed Lubrication in Automotive Valve Train

2014 ◽  
Author(s):  
Ning Ren ◽  
Frances E. Lockwood ◽  
Ilya Piraner ◽  
Amit Gabale
Keyword(s):  
Driving Forces ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Valve Train ◽  
Engine Oil ◽  
Modeling And Analysis ◽  
Low Viscosity ◽  
Lubrication Performance ◽  
Engine Components

Environmental regulation and high fuel cost are among the leading driving forces behind the demand of energy efficient vehicles. Together with new engine hardware technologies, engine oil is expected to significantly contribute to improving vehicle fuel economy. New fuel-efficient engine oils are often formulated with advanced additives and low viscosity base oils. Understanding the lubrication performance at key engine components such as the cam and follower in valve train systems becomes critically important to ensure engine durability with the new fuel-efficient low viscosity oils. A full numerical mixed lubrication analysis of the cam and roller follower pair is conducted using the three dimensional line contact mixed elastohydrodynamic lubrication (EHL) model. The results show significant effects of surface roughness, topography, slide-to-roll ratio, and viscosity grade on lubricant film, contact pressure, and subsurface stress.

An improved stiffness model for line contact elastohydrodynamic lubrication and its application in gear pairs

2020 ◽  
Vol 72 (5) ◽  
pp. 703-708 ◽  
Author(s):  
Jiaxing Pei ◽  
Xu Han ◽  
Yourui Tao
Keyword(s):  
External Load ◽  
Contact Stiffness ◽  
Elastohydrodynamic Lubrication ◽  
Line Contact ◽  
Content Type ◽  
Meshing Stiffness ◽  
Proposed Model ◽  
Stiffness Model ◽  
Film Stiffness ◽  
Ehl Contact

Purpose The purpose of this paper is to propose an simple and efficient stiffness model for line contact under elastohydrodynamic lubrication (EHL) and to investigate the gear meshing stiffness by the proposed model. Design/methodology/approach The method combines the surface contact stiffness and film stiffness as EHL contact stiffness. The EHL contact stiffness can be calculated by the external load and displacement of the load action point. The displacement is the sum of deformation of the film and contact surface and is equal to the distance of the mutual approach of two contact bodies. Findings The conclusion is drawn that the contact stiffness calculated by the proposed model is smaller than that by the minimum film model and larger than that by the mean film model. It is also concluded that the gear meshing stiffness under EHL is slightly smaller than that under dry contact. Originality/value The EHL contact stiffness can be obtained by the increment of external load and mutual approach directly. The calculation of oil film stiffness and surface contact stiffness separately is avoided. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2019-0465

scholarly journals New analytical model of elastic-plastic contact for three-dimensional rough surfaces considering interaction of asperities

Friction ◽  
2021 ◽  
Author(s):  
Yuqin Wen ◽  
Jinyuan Tang ◽  
Wei Zhou ◽  
Lin Li ◽  
Caichao Zhu
Keyword(s):  
Plastic Deformation ◽  
Surface Science ◽  
Calculation Method ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Three Dimensional ◽  
Correction Method ◽  
Elastic Plastic ◽  
Contact Distance ◽  
The Matrix

AbstractThe contact calculation of three-dimensional real rough surfaces is the frontier field of tribology and surface science. In this study, we consider the interaction and elastic-plastic deformation characteristics of asperities and further, propose an analytical contact calculation method for rough surfaces considering the interaction of asperities. Based on the watershed algorithm, the rough surface is segmented and the asperities are reconstructed into ellipsoids. According to the height relationship between the asperities, the definition of the deformation reference height of the matrix between each couple of asperities is provided. Subsequently, the calculation formula of the substrate deformation is provided according to the local contact pressure considering the elastic-plastic deformation of the asperity, and the contact state under a specific load is determined using the iterative correction method. The results correspond with those of finite element numerical calculation and the study reveals the following: (1) compared with the results obtained without considering the asperity interaction, contact area, distance, and stiffness will be reduced by 6.6%, 19.6%, and 49.5%, respectively, when the influence of asperity interaction is considered; (2) the interaction of the asperities has the greatest influence on the surface contact distance and stiffness. Under the same load, the existence of asperity interaction will reduce the contact distance, area, and stiffness; (3) considering the interaction of the asperities, the higher asperity will bear more load, but it will simultaneously reduce the contact of the surrounding area and increase that of the distant area. The calculation method proposed in this study has the advantages of high calculation efficiency and accuracy, thus, providing the calculation basis and method for subsequent studies on service performance of rough surfaces, such as the calculation of contact stiffness and fatigue performance analysis of rough surfaces.

A Numerical Model to Predict Dynamic Performance of Layered Gears at Starved Lubrication

2019 ◽  
Author(s):  
Qingbing Dong ◽  
Jing Wei ◽  
Yan Li ◽  
Lixin Xu
Keyword(s):  
Reynolds Equation ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Material System ◽  
Stress Concentrations ◽  
Damage Resistance ◽  
Influence Coefficients ◽  
Load Carrying ◽  
Potential Energy Method

Abstract Gears of modern industry are required to have a good fatigue performance to transmit power and motion through the contact interfaces. Composite layered surfaces can effectively improve the damage resistance of gears and decrease the friction coefficients. However, improper surface modification may induce intensive stress concentrations at the joint interfaces of the strengthening layers and cause unexpected damages to the flanks. Furthermore, the amount of lubricant at the inlet may probably be insufficient to establish fully flooded condition, which may result in starvation and accelerate damages to the gear sets. In this study, a starved elastohydrodynamic lubrication (EHL) model in three-dimensional (3D) line contact for layered gears is developed. The potential energy method is employed to determine the load distribution along the action line. The loading force is assumed to be balanced by the lubrication pressure, which is derived by discretizing the dimensional Reynolds equation into a solvable matrix with the consideration of the enforced boundary conditions due to the inlet oil supply. The transient evolution of lubrication is investigated to evaluate the load-carrying capability of the lubricant film at various starvation conditions. The influence coefficients related to the displacements and stresses of the layered material system are determined with the assistance of the fast Fourier transform (FFT) algorithm, and the effects of the layer properties and the fabrication methods are evaluated. Such analysis may provide insightful information for the optimization of material systems with fabricated layers and engineering design of gears.

scholarly journals Theoretical and Experimental Study on Normal Contact Stiffness of Plane Joint Surfaces with Surface Texturing

2021 ◽  
Author(s):  
Chaochao Yin ◽  
Haihong Huang ◽  
Dan Zhou ◽  
Zhifeng Liu
Keyword(s):  
Rough Surface ◽  
Contact Stiffness ◽  
Fractal Theory ◽  
Surface Texturing ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Normal Contact ◽  
Joint Surfaces ◽  
Normal Contact Stiffness ◽  
Plane Joint

Abstract Effects of surface texturing on the normal contact stiffness of joint surfaces had been investigated by experiments in many previous researches; however, there are relatively few theoretical models in this regard. The rough surface with surface texturing can be divided into two parts: the textured zone and the remaining zone, and their theoretical models are established respectively in this research considering surface morphology and material properties. For the textured zone, micro textures are modeled theoretically based on the three-dimensional topographic data obtained via a VK-X250 type laser profilometer from KEYENCE. For the remaining zone, the model of normal contact stiffness is established based on the fractal theory for the surface topography description and elastoplastic deformation of surface asperities, and the structure function method is used to calculate the fractal dimension of rough surface profiles. In the experiment, the normal contact stiffness of specimens is obtained under different normal loads, and the test results are compared with the theoretical predictions. The result shows that the predictions of proposed theoretical model are in good agreement with the experimental data. For the joint surfaces with Sa > 2.69 μm, the normal contact stiffness can be effectively increased through proper surface texturing.

Sign in / Sign up

Export Citation Format

Share Document