An Experimental Study of Some of the Factors Affecting the Contact Conditions and the Slip between a Rolling Ball and Its Track

1967 ◽  
Vol 182 (1) ◽  
pp. 757-768 ◽  
Author(s):  
J. Hailing ◽  
M. A. Al-Qishtaini
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Wear Debris ◽  
Normal Load ◽  
Operating Conditions ◽  
Hydrodynamic Effect ◽  
Contact Conditions ◽  
Factors Affecting ◽  
Rolling Ball ◽  
Theoretical Considerations

The problem of a rolling ball subjected to combined normal load and tangential tractions has been studied for a variety of operating conditions. It is shown that for dry steady state loading the resultant slip may be explained in terms of a microslip theory based on the differential elastic straining of the ball and the track. Such results necessitate a careful experimental technique in which the surfaces must be free from contamination and loose wear debris. It is also shown that the preceding arguments are not significantly affected by dynamically varying loads or by speed variations in the range 0-150 in/min. The slip behaviour is found to be markedly affected by the presence of a lubricant. The behaviour with load and speed now indicates a definite hydrodynamic effect, although the theoretical film thickness is considerably less than the surface roughness. These results agree well with the results of other investigations for similar conditions. Using these experimental results and theoretical considerations a tentative power law formulation for the slip under such conditions is proposed.

scholarly journals INFLUENCE OF ROUGHNESS ON THE TRIBOLOGICAL BEHAVIOR OF A STEEL-STEEL COUPLE LUBRICATED WITH THREAD COMPOUND

2019 ◽  
Vol 49 (3) ◽  
pp. 193-200
Author(s):  
N. A. ZABALA ◽  
P. CASTRO ◽  
Walter TUCKART
Keyword(s):  
Surface Roughness ◽  
High Pressure ◽  
Tribological Behavior ◽  
Normal Load ◽  
Roughness Parameter ◽  
Small Scale ◽  
Contact Conditions ◽  
Threaded Joints ◽  
Copper Zinc ◽  
Wear Damage

The purpose of this study is to determinate the influence of surface roughness on the tribological behavior of a lubricated steel against steel tribosystem. Tests were carried out at high pressure and slow sliding speed, in order to simulate at small scale, the contact conditions found in the seal of the threaded joints used in oil & gas casing and tubing strings. Tests were carried out with a simplified block-onring test, varying the surface roughness of rings between 1.3 to 3 m Ra values. A thread compound lubricant containing lead, copper, zinc and graphite was used. During each cycle of test, the normal load was varied linearly between 250 N and 7000 N. An exponential correlation between Ra and Rt roughness values with the wear damage was found and the wear damage of the blocks decreases about 40 percent with the increasing of initial Ra roughness parameter in the movil surface.

Changes in Surface Topography with Running-In

1968 ◽  
Vol 183 (16) ◽  
pp. 57-65 ◽  
Author(s):  
R. Østvik ◽  
H. Christensen
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Surface Topography ◽  
Mixed Lubrication ◽  
Contact Conditions ◽  
Line Contacts

The paper will describe the results of an experimental study of changes in surface roughness and contact conditions as running-in and wear take place. Line contacts under conditions of mixed lubrication in both sliding and sliding with rolling have been studied.

Numerical investigation of sliding friction behaviour and mechanism of engineering surfaces

2019 ◽  
Vol 71 (2) ◽  
pp. 205-211 ◽  
Author(s):  
Xiaogang Zhang ◽  
Yali Zhang
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Sliding Friction ◽  
Normal Load ◽  
Numerical Results ◽  
Operating Conditions ◽  
Friction Mechanism ◽  
Content Type ◽  
Optimal Surface ◽  
Friction Behaviour

Purpose This study aims to investigate the sliding friction behaviour and mechanism of engineering surfaces. Design/methodology/approach A new numerical approach is proposed. This approach derives the macroscale friction coefficient from microscale asperity interactions. By applying this approach, the sliding friction behaviour under different operating conditions were investigated in terms of molecular and mechanical components. Findings Numerical results demonstrate an independent relationship between normal load and friction coefficient, which is governed by the saturated plastic ratio. Numerical results also demonstrate that under very small load, an increase in load increases the friction coefficient. In addition, numerical results confirm the existence of optimal surface roughness where the friction coefficient is the lowest. For the surface profiles used in the current calculation, an optimal surface roughness value is obtained as Rq = 0.125 μm. Originality/value This new approach characterizes the deterministic relationship between macroscale friction coefficient and microscale asperity molecular/mechanical interactions. Numerical results facilitate the understanding of sliding friction mechanism.

Static Friction Experiments and Verification of an Improved Elastic-Plastic Model Including Roughness Effects

2007 ◽  
Vol 129 (4) ◽  
pp. 754-760 ◽  
Author(s):  
Chul-Hee Lee ◽  
Andreas A. Polycarpou
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Wear Debris ◽  
Normal Load ◽  
Static Friction ◽  
Displacement Rate ◽  
Experimental Measurements ◽  
Roughness Effects ◽  
Elastic Plastic ◽  
Static Friction Coefficient

An experimental study was conducted to measure the static friction coefficient under constant normal load and different interface conditions. These include surface roughness, dwell time, displacement rate, as well as the presence of traces of lubricant and wear debris at the interface. The static friction apparatus includes accurate measurement of friction, normal and lateral forces at the interface (using a high dynamic bandwidth piezoelectric force transducer), as well as precise motion control and measurement of the sliding mass. The experimental results show that dry surfaces are more dependent on the displacement rate prior to sliding inception compared to boundary lubricated surfaces in terms of static friction coefficient. Also, the presence of wear debris, boundary lubrication, and rougher surfaces decrease the static friction coefficient significantly compared to dry smooth surfaces. The experimental measurements under dry unlubricated conditions were subsequently compared to an improved elastic-plastic static friction model, and it was found that the model captures the experimental measurements of dry surfaces well in terms of the surface roughness.

scholarly journals Influence of Rock Properties on Wear of M and SR Grade Rubber with Varying Normal Load and Sliding Speed

2017 ◽  
Vol 62 (3) ◽  
pp. 1787-1793 ◽  
Author(s):  
Samir Kumar Pal ◽  
K.U.M. Rao ◽  
P. Sathish Kumar ◽  
R. Rajasekar
Keyword(s):  
Surface Roughness ◽  
Shear Strength ◽  
Normal Load ◽  
Operating Conditions ◽  
Rock Properties ◽  
Sliding Speed ◽  
Lower Load ◽  
Conveyor Belts ◽  
Material Transportation ◽  
Set Up

AbstractRubbers are interesting materials and are extensively used in many mining industries for material transportation. Wear of rubber is a very complex phenomenon to understand. The present study aims to explain the influence of rock properties on wear of M and SR grade rubber used in top cover of conveyor belts. Extensive laboratory experiments were conducted under four combinations of normal load and sliding speed. The wear of both the rubber types were analyzed based on the rock properties like shear strength, abrasivity index and fractal dimension. A fully instrumented testing set up was used to study the wear of rubber samples under different operating conditions. In general, wear was higher for M grade rubber compared to SR grade rubber. Increase in shear strength of rocks depicts decreasing trend for the wear of M and SR grade rubber at lower load conditions. Moreover, a higher load combination displays no definite trend in both the rubbers. The strong correlation between the wear of rubber and frictional power for all rubber-rock combinations has given rise to the parameter A, which reflects the relative compatibility between the rubber and rock. Increase of Cerchar’s Abrasivity Index of rocks shows gradual enhancement in wear for M grade rubber in all the load and speed combinations whereas, it fails in SR grade rubber due to its higher strength. The wear of rubber tends to decrease marginally with the surface roughness of rocks at highest normal load and sliding speed in M grade rubber. However, the wear of M and SR grade rubber is influenced by the surface roughness of rocks.

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