Rolling and Sliding Contact Stress Parameters in Elastohydrodynamic Lubrication

1967 ◽  
Vol 34 (2) ◽  
pp. 471-477 ◽  
Author(s):  
R. A. Schoeppel ◽  
R. M. Evan-Iwanowski
Keyword(s):  
Pressure Distribution ◽  
Contact Stress ◽  
Contact Area ◽  
Elastohydrodynamic Lubrication ◽  
Considerable Change ◽  
Rolling Contact ◽  
Shear Stresses ◽  
High Speeds ◽  
Pressure Peak ◽  
Distribution Studies

The fatigue life at high operating speeds of machine components, such as bearings, gears, and cams, depends upon the shape and magnitude of the elastohydrodynamic pressure distribution. Studies show that two bodies in rolling contact at high speeds indicate a significant departure from the usual Hertzian pressure distribution present at low rolling speeds. The contact stress distribution for an elastohydrodynamic pressure distribution in an infinitely large plate is determined in this paper. The pressure peak on the outlet side of the contact area and the long pressure sweep on the inlet side of the contact area create a pressure distribution which is asymmetrical. The pressure peak has a significant effect on the normal and shear stresses. Superimposing contact stresses due to sliding indicates a considerable change in the stresses resulting from sliding direction.

A Coupled Approach for Modelling Rolling Contact Fatigue Cracks Under Elastohydrodynamic Lubrication

2009 ◽  
Author(s):  
R. Balcombe ◽  
M. T. Fowell ◽  
A. V. Olver ◽  
D. Dini
Keyword(s):  
Fluid Flow ◽  
Elastic Deformation ◽  
Contact Area ◽  
Fatigue Cracks ◽  
Moving Load ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Contact ◽  
Fluid Solid Interaction

In this paper we present a coupled method for modelling fluid-solid interaction within a crack generated in rolling contact fatigue (RCF) in the presence of lubrication. The technique describes the fluid flow in the contact area and within the crack and explores how this affects the elastic deformation of the solid while the moving load traverses the cracked region. It is argued that this approach sheds light on the instantaneous response of the system, therefore providing a more physically-accurate description of the phenomenon under investigation.

Application of Dang Van criterion to rolling contact fatigue in wind turbine roller bearings under elastohydrodynamic lubrication conditions

2013 ◽  
Vol 228 (12) ◽  
pp. 2079-2089 ◽  
Author(s):  
Michele Cerullo
Keyword(s):  
Wind Turbine ◽  
Pressure Distribution ◽  
High Cycle Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Contact ◽  
Cycle Fatigue ◽  
Roller Bearings ◽  
Very High Cycle Fatigue ◽  
Very High ◽  
Dang Van Criterion

A 2D plane strain finite element program has been developed to investigate very high cycle fatigue in wind turbine roller bearings due to rolling contact. Focus is on fatigue in the inner ring, where the effect of residual stresses and hardness variation along the depth is accounted for. Both classic Hertzian and elastohydrodynamic lubrication theories have been used to model the pressure distribution acting on the inner raceway and results are compared according to the Dang Van multiaxial fatigue criterion. The contact on the bearing raceway is simulated by substituting the roller with the equivalent contact pressure distribution. The material used for the simulations is taken to be an AISI 52100 bearing steel and linear elastic behavior is here assumed. The effect of different residual stress distributions is also studied, as well as the effect of variable hardness along the depth, relating its values to the fatigue limit parameters for the material. It is found that both for Hertzian and elastohydrodynamic lubrication contacts, the Dang Van criterion predicts that fatigue failure will first occur in the subsurface region and that, regardless of the specific pressure distribution used, the hardness distribution can have a significant influence on the safety against failure for bearings subjected to very high cycle fatigue loading.

Non-Newtonian behaviour in elastohydrodynamic lubrication

1974 ◽  
Vol 337 (1608) ◽  
pp. 101-121 ◽  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Critical Stress ◽  
Elastohydrodynamic Lubrication ◽  
Critical Factor ◽  
Molecular Size ◽  
High Speeds ◽  
Oil Films

The relation between shear stress and shear rate has been determined for elastohydrodynamic oil films. At low values the rate of shear is directly proportional to the shear stress, but at higher values the shear rate increases more rapidly than the stress. It is shown that the critical factor is the magnitude of the shear stress, not the shear rate, and that this critical magnitude depends upon the pressure and the molecular size. Above the critical stress, in the non-Newtonian region, the shape of the curve relating the stress to the rate of shear depends upon the distribution of the sizes of the molecules in the oil. It is shown that in elastohydrodynamic conditions the limits of Newtonian behaviour are frequently exceeded and that this is liable to influence the pressure distribution, the magnitude of the traction, the generation of heat, and, at high speeds, the value of the film thickness.

The Lubrication Regime at Pin-Pulley Interface in Chain CVTs

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
G. Carbone ◽  
M. Scaraggi ◽  
L. Soria
Keyword(s):  
Pressure Distribution ◽  
High Pressures ◽  
Elastohydrodynamic Lubrication ◽  
Asperity Contact ◽  
Normal Stress Distribution ◽  
Lubrication Regime ◽  
Starting Point ◽  
High Fatigue ◽  
Variable Transmission ◽  
Pressure Peak

This paper deals with the strongly nonstationary squeeze of an oil film at the interface between the chain pin and pulley in chain belt continuously variable transmission. We concentrate on the squeeze motion as it occurs as soon as the pin enters the pulley groove. The duration time to complete the squeeze process compared with the running time the pin takes to cover the entire arc of contact is fundamental to understand whether direct asperity-asperity contact occurs between the two approaching surfaces to clarify what actually is the lubrication regime (elastohydrodynamic lubrication (EHL), mixed, or boundary) and to verify if the Hertzian pressure distribution at the interface can properly describe the actual normal stress distribution. The Hertzian pressure solution is usually taken as a starting point to design the geometry of the pin surface; therefore, it is of utmost importance for the designers to know whether their hypothesis is correct or not. Taking into account that the traveling time, the pin spends in contact with the pulley groove, is of about 0.01 s, we show that rms surface roughness less than 0.1 μm, corresponding to values adopted in such systems, guarantees a fully lubricated EHL regime at the interface. Therefore, direct asperity-asperity contact between the two approaching surfaces is avoided. We also show that the Hertzian solution does not properly represent the actual pressure distribution at the pin-pulley interface. Indeed, after few microseconds a noncentral annular pressure peak is formed, which moves toward the center of the pin with rapidly decreasing speed. The pressure peak can grow up to values of several gigapascals. Such very high pressures may cause local overloads and high fatigue stresses that must be taken into account to correctly estimate the durability of the system.

Surface Observation of Induction-Heated 13Cr-2Ni-2Mo Stainless Steel after Interrupted Fatigue Testing under Rolling Contact Stress in Water

2021 ◽  
Vol 315 ◽  
pp. 72-76
Author(s):  
Koshiro Mizobe ◽  
Takahiro Matsueda ◽  
Gakuto Shinohara ◽  
Takuya Shibukawa ◽  
Katsuyuki Kida
Keyword(s):  
Stainless Steel ◽  
Contact Stress ◽  
Contact Area ◽  
Contact Surface ◽  
Fatigue Testing ◽  
Wear Behavior ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Wear Loss

In order to investigate the wear behavior of induction-heated 13Cr-2Ni-2Mo stainless steel, we performed the rolling contact fatigue (RCF) tests in water. We interrupted the RCF test at each 1.0×105 cycles and measure the wear loss and observed the contact surface. After the RCF tests, we found the oxygen concentration area in the contact area.

Frictional traction in elastohydrodynamic lubrication

1973 ◽  
Vol 332 (1591) ◽  
pp. 505-525 ◽  
Keyword(s):  
Pressure Distribution ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Speed ◽  
Characteristic Relaxation Time ◽  
Shear Stresses ◽  
Pure Rolling ◽  
Systematic Pattern ◽  
Quantitative Examination ◽  
Very High ◽  
Limiting Value

The traction in pure rolling has been measured at constant temperature over a range of load and speed. Measurements have been made at controlled temperatures of 10, 20 and 30 °C on a paraffinic and a naphthenic based mineral oil. The results form a systematic pattern and provide a fuller picture of the variation of the enhanced viscosity of the oil with load and rolling speed than has been available hitherto. It is shown that the viscosity tends towards a limiting value when the rolling speed is low. The results are compared with recent measurements by Hamilton & Moore of the variation of the pressure distribution with load and speed. Both sets of results appear to suggest that the response of viscosity to the application of pressure is not instantaneous, but is delayed with a characteristic relaxation time. However, quantitative examination shows that this hypothesis is untenable. It is then shown that the variation of viscosity with rolling speed originates from the variation of the pressure distribution with speed. In the region of highest pressure the response of viscosity to pressure is normal. In the inlet and outlet zones, the shear stresses are very high and in these regions the oils exhibit non-Newtonian behaviour.

Some Calculations to Assess the Effect of Spin on the Tractive Capacity of Rolling Contact Drives

1970 ◽  
Vol 185 (1) ◽  
pp. 1015-1022 ◽  
Author(s):  
S. Y. Poon
Keyword(s):  
Rheological Properties ◽  
Contact Area ◽  
Rolling Direction ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Contact ◽  
Contact Conditions ◽  
Transmission Fluid

The tractive capacity of rolling with superimposed spinning motion in elastohydrodynamic lubrication is analysed on the basis of a simplification, that the contact area can be divided into strips in the direction of rolling and that the total traction carried by the contact can be obtained from the sum of these strips. For the contact conditions considered here, the slide (or creep) occurs in the rolling direction. It is shown that the traction versus slide relationship for this situation can be constructed from the basic traction data of the lubricant provided by a two-disc machine. The results can be used to assess the performance of a rolling contact drive design. The analysis also highlights the essential ***rheological properties of a good transmission fluid.

Method for Calculating Plastic Deformation of High Resolution and Large Contact Area

2021 ◽  
Vol 144 (1) ◽  
Author(s):  
S. Sklenak ◽  
D. Mevissen ◽  
J. Brimmers ◽  
C. Brecher
Keyword(s):  
Plastic Deformation ◽  
High Resolution ◽  
Pressure Distribution ◽  
Rough Surface ◽  
Tribological Properties ◽  
Contact Area ◽  
Three Dimensional ◽  
Rolling Contact ◽  
Contact Algorithm ◽  
Large Contact Area

Abstract In a rolling contact, the tribological properties in terms of friction, wear, and fatigue are significantly influenced by the surface roughness. Due to solid contact of the surfaces in the contact area, the roughness and thus also the tribological properties change during the service life of the contact. The initial load leads to major changes of the tribological properties figured out by Brecher et al. (2019, “Influence of the Metalworking Fluid on the Micropitting Wear of Gears,” Wear, 61(434–435), p. 202996). Prediction of the initial changes in topography in the contact area is necessary for specific optimization of rolling contacts. Especially for dry rolling–sliding contact, the roughness of the surfaces is crucial for the lifetime, which is part of the investigations within the DFG priority program 2074 (357505886). In this work, an elastic-plastic contact algorithm for calculating plastic deformation for dry contact of rough surfaces with large contact area and high resolution is presented. Due to the nonlinearity behavior associated with plastic deformation, the plastic contact algorithm is based on an iterative approach. An optimized meshing strategy is implemented to calculate the elastic pressure distribution on the surface. Corresponding to the two-dimensional pressure distribution, the three-dimensional stress distribution allows the consideration of residual stresses and interactions of the microscopic peaks of the rough surface. Furthermore, the three-dimensional plastic strain distribution allows the application of an analytical approach to represent the plastic deformation of the surface. Finally, the solution of a plastic contact calculation with an exemplary topography measured on a real rough surface is presented.

Method for Calculating Normal Pressure Distribution of High Resolution and Large Contact Area

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
C. Brecher ◽  
D. Renkens ◽  
C. Löpenhaus
Keyword(s):  
High Resolution ◽  
Pressure Distribution ◽  
Surface Topography ◽  
Contact Area ◽  
Normal Pressure ◽  
Rolling Contact ◽  
Sliding Contacts ◽  
Contact Areas ◽  
Irregular Grids ◽  
Disk Rolling

The exact calculation of contact stresses below the surface is the basis for optimizing load capacity of heavily loaded rolling–sliding contacts. The level of stress is significantly influenced by the normal pressure distribution within the contact area, which occurs as a result of the transferred normal force and the contact geometry. In this paper, a new method for high resolution pressure calculation of large contact areas is presented. By this, measured surface topography can be taken into account. The basis of the calculation method is the half-space theory according to Boussinesq/Love. Instead of regular grids, optimized meshing strategies are applied to influence the calculation efforts for large contact areas. Two objectives are pursued with the targeted meshing strategy: on the one hand, the necessary resolution for measured surface structures can be realized; while on the other hand, the total number of elements is reduced by a coarse grid in the surrounding areas. In this way, rolling–sliding contacts with large contact areas become computable with conventional simulation computers. Using the newly developed “method of combined solutions,” the overall result is finally composed by the combination of section of separate solutions, which are calculated by consecutively shifting the finely meshed segment over the entire contact area. The vital advancement in this procedure is the introduction of irregular grids, through which the cross influences are not neglected and fully regarded for every separate calculation. The presented methodology is verified stepwise in comparison to the Hertzian theory. The influence of irregular grids on the calculation quality is examined in particular. Finally, the calculation approach is applied to a real disk-on-disk rolling contact based on measured surface topography.

Boundary slips induced temperature rise and film thickness reduction under sliding/rolling contact in thermal elastohydrodynamic lubrication

2021 ◽  
pp. 1-27
Author(s):  
Xianghua Meng ◽  
Jing Wang ◽  
Gyoko Nagayama
Keyword(s):  
Film Thickness ◽  
Contact Area ◽  
Temperature Rise ◽  
Elastohydrodynamic Lubrication ◽  
Volume Ratio ◽  
Velocity Slip ◽  
Rolling Contact ◽  
Thickness Reduction ◽  
Thermal Slip ◽  
Entrainment Velocity

Abstract Temperature rise and film thickness reduction are the most important factors in elastohydrodynamic lubrication (EHL). In the EHL contact area, interfacial resistances (velocity/thermal slips) induced by the molecular interaction between lubricant and solid become significant due to the large surface/volume ratio. Although the velocity slip has been investigated extensively, less attention has been paid on the thermal slip in the EHL regime. In this study, numerical simulations were conducted by applying three cases of boundary slips to surfaces under sliding/rolling contacts moving in the same direction for the Newtonian thermal EHL. We found that the coupled velocity/thermal slips lead the most significant temperature rise and film thickness reduction among the three cases. The velocity slip results in a lower temperature in the lubricant and solids, whereas the thermal slip causes a temperature rise in the entire contact area as the film thickness decreases simultaneously. Furthermore, the effect of thermal slip on lubrication is more dominant than that of velocity slip while increases the entrainment velocity or slide–roll ratio.

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