Influence of Surface Roughness Lay Directionality on Scuffing Failure of Lubricated Point Contacts

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
S. Li
Keyword(s):  
Frictional Heat ◽  
Bulk Temperature ◽  
Asperity Contact ◽  
Load Range ◽  
Rolling Velocity ◽  
Sliding Direction ◽  
Disk Contact ◽  
Continuous Surface ◽  
Scuffing Failure ◽  
Resistance Performance

The influence of roughness lay directionality on scuffing failure is studied considering different roughness lay direction combinations of the contacting surfaces of a ball-on-disk contact. Using a recently developed scuffing model Li et al., (2013, “A Model to Predict Scuffing Failures of a Ball-On-Disk Contact,” Tribol. Int., 60, pp. 233–245)., the bulk temperature and flash temperature are predicted for each roughness lay combination within the load range from 0.76 GPa to 2.47 GPa in a step-wise manner under the rolling velocity of 10 m/s and slide-to-roll ratio of −0.5 to show substantial impacts of roughness lay directionality on scuffing resistance performance (SRP). It is found (i) the lay direction combination that results into contacts of asperities with small contact radii leads to increased local contact pressures and frictional heat flux, reducing SRP; (ii) the continuous asperity contact along the sliding direction leads to continuous surface temperature rise and lowers SRP; and (iii) the lubricant side leakage caused by the pressure gradient in the direction normal to the sliding direction leads to reduced SRP. With these main mechanisms in effect, the SRP of a contact decreases as the deviation between the roughness texture orientations of the two surfaces increases. The surfaces with their roughness lay directions both perpendicular to the sliding direction exhibits best SRP. The surfaces with one roughness lay direction positioned in line with the direction of sliding and the other positioned perpendicular to the sliding direction shows worst SRP.

scholarly journals A Wear Simulation Method for Mechanical Face Seals under Friction Instability Conditions

2020 ◽  
Vol 10 (8) ◽  
pp. 2875
Author(s):  
Wentao He ◽  
Shaoping Wang ◽  
Chao Zhang ◽  
Xi Wang ◽  
Di Liu
Keyword(s):  
Contact Pressure ◽  
Torsional Stiffness ◽  
Frictional Heat ◽  
Axial Stiffness ◽  
Asperity Contact ◽  
Wear Simulation ◽  
Time Rate ◽  
Wear Time ◽  
Face Seals ◽  
Non Gaussian

Mechanical face seals are crucial components of automotive cooling water pumps and affect the safe operation of the pump. This article focuses on the effect of friction instabilities on the wear of the seals. Friction instabilities, such as stick-slip, occur when the axle is decelerated or operated at a low speed. Based on previous studies, a simulation model is proposed of a mechanical face seal that considers the interaction of asperities of non-Gaussian surfaces and the heat transfer between the sealing rings. According to the Archard wear equation, a numerical wear simulation is performed, and the wear distance rate and wear time rate are obtained. A comparison of the contact pressure of the Gaussian and non-Gaussian surfaces indicates that the latter is more likely to generate high contact pressure, thereby producing more significant wear. The viscous shear heat and frictional heat due to asperity contact decrease with an increase in the thickness of the tapered film. As the shaft decelerates, the wear distance rate increases with an increase in the axial stiffness. The axial damping only affects the duration of the oscillations. The wear time rate decreases with an increase in the torsional stiffness and torsional damping. The results of this research provide guidelines for estimating the wear of mechanical seals when friction instabilities occur.

Numerical Simulations of Slider Interaction With Multiple Asperity Using Hertzian Contact Model

1995 ◽  
Vol 117 (4) ◽  
pp. 575-579 ◽  
Author(s):  
Ellis Cha ◽  
D. B. Bogy
Keyword(s):  
Disk Drive ◽  
Contact Model ◽  
Hertzian Contact ◽  
Flying Height ◽  
Radius Of Curvature ◽  
Asperity Contact ◽  
Disk Contact ◽  
Suspension Dynamics ◽  
Magnetic Hard Disk ◽  
Hertzian Contact Model

A numerical simulation of slider-disk contact in a magnetic hard disk drive is studied using the Hertzian contact model. The slider-disk contact is caused by flying height fluctuation due to disk runout for very low flying sliders. The rough disk topography is generated numerically by combining a sinusoidal waviness and a Gaussian roughness. For each asperity contact, the radius of curvature is calculated from the disk topography, and the radius is used to calculate the contact force using the Hertzian contact model. The slider’s response to a single asperity calculated using the Hertzian contact model agrees well with the result obtained using the impulse-momentum based contact model. The simulation results of slider-disk contact including suspension dynamics are calculated with and without friction for a “nano-slider.”

Numerical Simulation of Engagement of Paper Based Wet Clutch Facing

1994 ◽  
Vol 116 (2) ◽  
pp. 232-237 ◽  
Author(s):  
Shinichi Natsumeda ◽  
Tatsuro Miyoshi
Keyword(s):  
Hydrodynamic Lubrication ◽  
Compressive Strain ◽  
Viscosity Reduction ◽  
Frictional Heat ◽  
Asperity Contact ◽  
Wet Clutch ◽  
Engagement Process ◽  
Torque Curve ◽  
The Many ◽  
Made In

Theoretical analysis was carried out on the engagement process of a paper based wet clutch. The annular multidisk clutch in a SAE#2 tester was chosen as an example. The average flow model on partial hydrodynamic lubrication proposed by Patir and Cheng was employed for the analysis of squeeze motion taking the permeability, the compressive strain, and the asperity contact of paper facing into account. Simultaneously, the equations of heat conduction were solved to calculate the viscosity reduction due to frictional heat generation. The theoretical torque curve agreed qualitatively with the experimental one in spite of the many assumptions made in this analysis.

Temperature Rise Simulation of Three-Dimensional Rough Surfaces in Mixed Lubricated Contact

1998 ◽  
Vol 120 (2) ◽  
pp. 310-318 ◽  
Author(s):  
Liangheng Qiu ◽  
Herbert S. Cheng
Keyword(s):  
Temperature Rise ◽  
Surface Film ◽  
Computing Time ◽  
Three Dimensional ◽  
Film Surface ◽  
Grid Method ◽  
Lubricant Film ◽  
Frictional Heat ◽  
Asperity Contact ◽  
Lubricated Contact

A numerical simulation of the temperature rise for a three-dimensional rough surface sliding against a smooth surface in mixed lubricated contact has been developed. The effects of lubricant film friction and solid asperity friction are considered in the simulation. The moving grid method, which greatly reduces the required computer memory size and computing time, is used to solve the coefficient matrix of temperature equations. The time-dependent surface temperature rise at very small subregions is obtained. Different friction coefficients for lubricant shearing, surface film shearing and dry solid asperity contact are used to simulate the change of frictional heat in mixed lubricated contact. A critical temperature criterion is used to determine whether the friction coefficient is controlled by lubricant film, surface film, or dry solid asperity contact. Solutions for different contact conditions are presented for verification of the present simulation

The Failure of Elastohydrodynamic Lubrication of Circumferentially Ground Discs

1976 ◽  
Vol 190 (1) ◽  
pp. 699-711 ◽  
Author(s):  
A. Dyson
Keyword(s):  
Contact Mechanics ◽  
Reasonable Agreement ◽  
Elastohydrodynamic Lubrication ◽  
Bulk Temperature ◽  
Scuffing Failure

SYNOPSIS A new theory is developed in an attempt to explain the scuffing failure of circumferentially ground discs. The characteristics of the surfaces of a particular pair of such discs just before scuffing took place have been analysed in detail. The roughness of the surfaces has been taken into account in the treatment both of the hydrodynamics and of the contact mechanics of the system. The disc bulk temperature at which high hydrodynamic pressures just fail to be generated shows a reasonable agreement with the temperature observed just before scuffing. The implications for the mechanism of scuffing are discussed.

Scuffing Failure in Heavily Loaded Slow Speed Conformal Sliding Contacts

1991 ◽  
Vol 113 (1) ◽  
pp. 182-191 ◽  
Author(s):  
M. C. Shen ◽  
H. S. Cheng ◽  
P. C. Stair
Keyword(s):  
Bulk Temperature ◽  
Slow Speed ◽  
Sliding Contacts ◽  
Formation Kinetics ◽  
Speed Range ◽  
Total Temperature ◽  
Scuffing Failure ◽  
Adsorption Desorption ◽  
Major Data ◽  
Good Agreement

Scuffing failure phenomenon is studied experimentally in heavily loaded slow speed conformal sliding contacts of two flat thrust washers in a regime close to boundary lubricated condition. Lubricants used are base oils of pure mineral oil and poly-α-olefin (PAO). Speed range is 0.76–33.0 cm/s. Material studied is hardened 52100 steel for both washers in contact. Scuffing threshold load at failure, friction, and surface bulk temperature are major data measured. The surface total temperature is determined with the measure bulk temperature in addition to the surface flash temperature calculated using Jaeger’s theory. Characteristic scuffing failure mechanisms are categorized in terms of various speed ranges. A simple model is proposed to predict scuffing failure based on theories in adsorption/desorption dominated lubricated wear and metal oxide formation kinetics. Good agreement is found between experimental data and theoretical prediction in terms of threshold load in certain speed range.

Scuffing Failure of Steel Discs: Conditions for the Failure of Elastohydrodynamic Lubrication

1990 ◽  
Vol 204 (2) ◽  
pp. 91-97 ◽  
Author(s):  
A Dyson ◽  
H P Evans ◽  
G Karami ◽  
M C Paliwal ◽  
R W Snidle
Keyword(s):  
Atmospheric Pressure ◽  
Elastohydrodynamic Lubrication ◽  
Bulk Temperature ◽  
Critical Temperatures ◽  
Lubricating Oils ◽  
Scuffing Failure

Scuffing tests run on circumferentially finished discs were analysed to determine the conditions for the failure of elastohydrodynamic lubrication according to Dyson's theory. The critical lubricant temperatures and viscosities derived from this analysis were compared with the temperatures and viscosities at atmospheric pressure and at the bulk temperature of the discs, as recorded by thermocouples embedded below the surfaces. Tests and corresponding calculations were made for three different lubricating oils and for two steels. The results of the comparison between measured and calculated critical temperatures and viscosities support the concept of scuffing failure as being related to the physical failure of elastohydrodynamic lubrication, even though the lubricants differed significantly in their scuffing behaviour.

Experimental and Computational Thermal Modeling of In Vitro Pin-on-Disk Tests of Ultra High Molecular Weight Polyethylene

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Kathleen A. Lewicki ◽  
Douglas W. Van Citters
Keyword(s):  
Molecular Weight ◽  
Coefficient Of Friction ◽  
Bovine Serum ◽  
Temperature Increase ◽  
Frictional Heating ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Frictional Heat ◽  
Bulk Temperature ◽  
Gravimetric Analysis

Frictional heating occurring during pin-on-flat tribotesting of ultrahigh molecular weight polyethylene (UHMWPE) pins was measured and modeled. A full factorial experiment was conducted to determine if testing parameters can produce sufficient frictional heat to alter tribological properties of the bovine serum used as lubricant in the system. Temperature of the surrounding bovine serum was monitored during tribotests using varying pin sizes and sliding speeds to determine typical temperature rises due to frictional heating. This work examined two sliding speeds (40 mm/s and 80 mm/s) and two pin diameters (6.35 mm and 9.5 mm) at a single static load. Gravimetric analysis for wear determination and coefficient of friction measurement were performed for each test. Results showed that frictional heating increased the bulk temperature of the surrounding serum and correlated to sliding speed and average coefficient of friction. No correlation was seen at this temperature range between serum temperature rise and wear rate, providing evidence that the tested parameters are acceptable for tribotesting of UHMWPE. A computational model was developed to predict bulk serum temperature increase. This model closely predicted the temperature increase to within 2 °C, which is sufficient accuracy for identifying if bovine serum protein precipitation is likely during tribotesting. This work serves as an initial estimate and prediction for appropriate testing parameters based on lubricant responses to frictional heating.

Antithrombin III Binding to Surface Immobilized Heparin and Its Relation to F Xa Inhibition

1987 ◽  
Vol 58 (04) ◽  
pp. 1064-1067 ◽  
Author(s):  
K Kodama ◽  
B Pasche ◽  
P Olsson ◽  
J Swedenborg ◽  
L Adolfsson ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Surface Coating ◽  
Antithrombin Iii ◽  
Lower Class ◽  
Biologically Active ◽  
High Affinity ◽  
Heparin Coating ◽  
Continuous Surface ◽  
Approximate Molecular Weight

SummaryThe mode of F Xa inhibition was investigated on a thromboresistant surface with end-point attached partially depoly-merized heparin of an approximate molecular weight of 8000. Affinity chromatography revealed that one fourth of the heparin used in surface coating had high affinity for antithrombin III (AT). The heparin surface adsorbed AT from both human plasma and solutions of purified AT. By increasing the ionic strength in the AT solution the existence of high and low affinity sites could be shown. The uptake of AT was measured and the density of available high and low affinity sites was found to be in the range of 5 HTid 11 pic.omoles/cmf, respectively Thus the estimated density of biologically active high and low ailmity heparm respectively would be 40 and 90 ng/cm2 The heparin coating did not take up or exert F Xa inhibition by itself. With AT adsorbed on both high and low affinity heparin the surface had the capacity to inhibit several consecutive aliquots of F Xa exposed to the surface. When mainly high affinity sites were saturated with AT the inhibition capacity was considerably lower. Tt was demonstrated that the density of AT on both high and low affinity heparin determines the F Xa inhibition capacity whereas the amount of AT on high affinity sites limits the rate of the reaction. This implies that during the inhibition of F Xa there is a continuous surface-diffusion of AT from sites of a lower class to the high affinity sites where the F Xa/AT complex is formed and leaves the surface. The ability of the immobilized heparin to catalyze inhibition of F Xa is likely to be an important component for the thromboresistant properties of a heparin coating with non-compromized AT binding sequences.

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