scholarly journals On a sliding friction model of boundary lubrication

2021 ◽  
Author(s):  
Can Wang
Keyword(s):  
Boundary Lubrication ◽  
Sliding Friction ◽  
Friction Model

Friction Force and Stresses Analysis for Contact of Assembled Details

2006 ◽  
Vol 113 ◽  
pp. 334-338
Author(s):  
Z. Dreija ◽  
O. Liniņš ◽  
Fr. Sudnieks ◽  
N. Mozga
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Plastic Deformation ◽  
Friction Force ◽  
Sliding Friction ◽  
Friction Model ◽  
Contact Interface ◽  
Finite Element Program ◽  
Elastic Plastic ◽  
Element Program

The present work deals with the computation of surface stresses and deformation in the presence of friction. The evaluation of the elastic-plastic contact is analyzed revealing three distinct stages that range from fully elastic through elastic-plastic to fully plastic contact interface. Several factors of sliding friction model are discussed: surface roughness, mechanical properties and contact load and areas that have strong effect on the friction force. The critical interference that marks the transition from elastic to elastic- plastic and plastic deformation is found out and its connection with plasticity index. A finite element program for determination contact analysis of the assembled details and due to details of deformation that arose a normal and tangencial stress is used.

Coupled thermo-mechanical sticking-sliding friction model along tool-chip interface in diamond cutting of copper

2021 ◽  
Vol 70 ◽  
pp. 578-592
Author(s):  
Shiquan Liu ◽  
Haijun Zhang ◽  
Liang Zhao ◽  
Guo Li ◽  
Chunyu Zhang ◽  
...  
Keyword(s):  
Sliding Friction ◽  
Friction Model ◽  
Diamond Cutting

scholarly journals Calculation and AFM Experimental Research on Slip Friction for Unlubricated Spherical Contact with Roughness Effect

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1428
Author(s):  
Shengguang Zhu ◽  
Liyong Ni
Keyword(s):  
Friction Force ◽  
Sliding Friction ◽  
Static Friction ◽  
Friction Model ◽  
Rigid Sphere ◽  
Roughness Effect ◽  
Force Microscopy ◽  
Comparison Results ◽  
Experimental Values ◽  
Calculation Models

Previous research on friction calculation models has mainly focused on static friction, whereas sliding friction calculation models are rarely reported. In this paper, a novel sliding friction model for realizing a dry spherical flat contact with a roughness effect at the micro/nano scale is proposed. This model yields the sliding friction by the change in the periodic substrate potential, adopts the basic assumptions of the Greenwood–Williamson random contact model about asperities, and assumes that the contact area between a rigid sphere and a nominal rough flat satisfies the condition of interfacial friction. It subsequently employs a statistical method to determine the total sliding friction force, and finally, the feasibility of this model presented is verified by atomic force microscopy friction experiments. The comparison results show that the deviations of the sliding friction force and coefficient between the theoretical calculated values and the experimental values are in a relatively acceptable range for the samples with a small plasticity index (Ψ ≤ 1).

A Model for Run-In and Other Transitions in Sliding Friction

1987 ◽  
Vol 109 (3) ◽  
pp. 537-543 ◽  
Author(s):  
Peter J. Blau
Keyword(s):  
Sliding Friction ◽  
Friction Model ◽  
Mathematical Framework ◽  
Semiempirical Model ◽  
System Parameters ◽  
Debris Accumulation ◽  
Scaling Parameters ◽  
Coefficient Versus ◽  
Specific Sliding ◽  
Empirical System

The mathematical framework for a sliding friction model for run-in and other tribological transitions is presented. The semiempirical model was developed to portray the commonly observed shapes, durations, and variations in kinetic friction coefficient versus sliding time curves. Terms in the model involve material properties and physical interface conditions such as transfer, debris accumulation, and surface roughness. The forms of individual terms are adjustable through the use of systemspecific scaling parameters in order to provide enough modeling flexibility to treat a variety of possible tribological conditions. Effects of such conditions as lubrication efficiency loss over time, and temperature build-up can be incorporated by modification of appropriate terms. Illustrative plots using the framework with several combined contributions are compared with experimental data from previous work. The basic framework of the model can be further developed to incorporate sub-models for specific sliding friction contributions and, in so doing, reduce the number of empirical system parameters required to model actual tribosystem behavior.

A Novel Friction Model Basing on Journal Bearing Theory for Reciprocating Compressor

2013 ◽  
Vol 456 ◽  
pp. 320-323 ◽  
Author(s):  
Le Wang ◽  
Bin Tang ◽  
Yuan Yang Zhao
Keyword(s):  
Friction Coefficient ◽  
Piston Ring ◽  
Sliding Friction ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Dynamic Change ◽  
Friction Model ◽  
Reciprocating Compressor ◽  
Oil Viscosity ◽  
Compressor Performance

The paper presents a comprehensive friction model of reciprocating compressor which is able to evaluate friction losses in moving parts. The model consists of crankshaft, connecting rod and piston all supported by bearings as well as the piston ring/cylinder interface viewed as sliding friction. Hydrodynamic lubrication theory reveals relationship between load and friction coefficient and was demonstrated to be helpful to give insight to the lubrication characteristics of journal bearing. The model gave the composition of friction losses, friction coefficient dynamic change with orbiting angle and effect of oil viscosity on compressor performance. The results showed that the friction losses of piston ring/cylinder interface and the rod big end bearing was most part of the friction losses and it was necessary to choose suitable oil viscosity to reach the optimum compressor performance.

A Boundary Lubrication Friction Model Sensitive to Detailed Engine Oil Formulation in an Automotive Cam/Follower Interface

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Rupesh Roshan ◽  
Martin Priest ◽  
Anne Neville ◽  
Ardian Morina ◽  
Xin Xia ◽  
...  
Keyword(s):  
Boundary Lubrication ◽  
Fuel Efficiency ◽  
Lubricant Additive ◽  
Friction Model ◽  
Operating Conditions ◽  
Valve Train ◽  
Engine Oil ◽  
Contact Friction ◽  
Boundary Lubrication Friction ◽  
Base Oil

Theoretical studies have shown that in severe operating conditions, valve train friction losses are significant and have an adverse effect on fuel efficiency. However, recent studies have shown that existing valve train friction models do not reliably predict friction in boundary and mixed lubrication conditions and are not sensitive to lubricant chemistry. In these conditions, the friction losses depend on the tribological performance of tribofilms formed as a result of surface–lubricant additive interactions. In this study, key tribological parameters were extracted from a direct acting tappet type Ford Zetec SE (Sigma) valve train, and controlled experiments were performed in a block-on-ring tribometer under conditions representative of boundary lubrication in a cam and follower contact. Friction was recorded for the tribofilms formed by molybdenum dithiocarbamate (MoDTC), zinc dialkyldithiophosphate (ZDDP), detergent (calcium sulfonate), and dispersant (polyisobutylene succinimide) additives in an ester-containing synthetic polyalphaolefin (PAO) base oil on AISI E52100 steel components. A multiple linear regression technique was used to obtain a friction model in boundary lubrication from the friction data taken from the block-on-ring tribometer tests. The model was developed empirically as a function of the ZDDP, MoDTC, detergent, and dispersant concentration in the oil and the temperature and sliding speed. The resulting friction model is sensitive to lubricant chemistry in boundary lubrication. The tribofilm friction model showed sensitivity to the ZDDP–MoDTC, MoDTC–dispersant, MoDTC–speed, ZDDP–temperature, detergent–temperature, and detergent–speed interactions. Friction decreases with an increase in the temperature for all ZDDP/MoDTC ratios, and oils containing detergent and dispersant showed high friction due to antagonistic interactions between MoDTC–detergent and MoDTC–dispersant additive combinations.

Molecular Dynamics Simulations of Sliding Friction of Rigid Sphere with Single Crystal Copper Surface

2013 ◽  
Vol 345 ◽  
pp. 167-171 ◽  
Author(s):  
Xiao Jing Yang ◽  
Xiao Jiang Yang
Keyword(s):  
Single Crystal ◽  
Sliding Friction ◽  
Normal Force ◽  
Three Dimensional ◽  
Copper Surface ◽  
Friction Model ◽  
Rigid Sphere ◽  
Stick Slip ◽  
Friction Process ◽  
Single Crystal Copper

Using LAMMPS to establish the three-dimensional sliding friction model of the nanoscale diamond hemisphere with the single-crystal copper surface. Simulation and solving the process of sliding friction, research the micro-contact area atomic states change in sliding friction process, and study the friction characteristics change when the rigid sphere sliding on rough surface of the single crystal copper with minute projections. The results indicate that, in the sliding friction process, the lattice of substrate atoms are damaged under the forces of the extrusion which also cause corresponding dislocation and deformation. In the direction of the hemisphere movement, generate the pileup and side stream phenomena, and produce furrows. Friction and normal force rapidly increase with the depth of contact, and then enter into a stable sliding phase. For the thermal motion of atoms, formation of dislocations and the stick-slip effect, the curves of friction and normal force present waves of sawtooth. Small defect on surface of the substrate almost have no effect on the process of sliding friction.

scholarly journals DESCRIPTIVE MODEL OF SLIDING FRICTION PROCESSES

2015 ◽  
Vol 2 ◽  
pp. 227
Author(s):  
Andris Martinovs ◽  
Vladimir Gonca
Keyword(s):  
Friction Coefficient ◽  
Surface Area ◽  
Contact Surface ◽  
Sliding Friction ◽  
Friction Model ◽  
Friction Process ◽  
Contact Surface Area ◽  
Optimal Surface ◽  
Sliding Friction Coefficient ◽  
The Mathematical Model

Paper analyses the sliding friction coefficient of rubber on concrete, timber and ceramic tile surfaces depending on the weight of the sliding object and contact surface area. It has been established that increase in the weight of the object makes sliding friction coefficient to grow. In the case of increase in size of contact area, sliding friction coefficient between rubber and concrete also increases, but it decreases between rubber- timber and rubber- tile. The mathematical model for description of sliding friction process has been developed which can be used to determine optimal surface area and a pattern as well as optimal weight of the sliding object in order to provide sufficient sliding friction. Model has five independent constants. It includes the contact surface area, the weight and the velocity of the sliding object, sliding friction coefficient, temperature and time.

scholarly journals Squeezing and stick–slip friction behaviors of lubricants in boundary lubrication

2018 ◽  
Vol 115 (26) ◽  
pp. 6560-6565 ◽  
Author(s):  
Rong-Guang Xu ◽  
Yongsheng Leng
Keyword(s):  
Phase Transition ◽  
Boundary Lubrication ◽  
Sliding Friction ◽  
Surface Force ◽  
Lubricant Film ◽  
Force Balance ◽  
Surface Boundary ◽  
Stick Slip ◽  
Squeeze Out ◽  
Dynamics Simulations

The fundamental questions of how lubricant molecules organize into a layered structure under nanometers confinement and what is the interplay between layering and friction are still not well answered in the field of nanotribology. While the phase transition of lubricants during a squeeze-out process under compression is a long-standing controversial debate (i.e., liquid-like to solid-like phase transition versus amorphous glass-like transition), recent different interpretations to the stick–slip friction of lubricants in boundary lubrication present new challenges in this field. We carry out molecular dynamics simulations of a model lubricant film (cyclohexane) confined between molecularly smooth surfaces (mica)––a prototypical model system studied in surface force apparatus or surface force balance experiments. Through fully atomistic simulations, we find that repulsive force between two solid surfaces starts at about seven lubricant layers (n= 7) and the lubricant film undergoes a sudden liquid-like to solid-like phase transition atn< 6 monolayers thickness. Shear of solidified lubricant films at three- or four-monolayer thickness results in stick–slip friction. The sliding friction simulation shows that instead of shear melting of the film during the slip of the surface, boundary slips at solid–lubricant interfaces happen, while the solidified structure of the lubricant film is well maintained during repeated stick–slip friction cycles. Moreover, no dilation of the lubricant film during the slip is observed, which is surprisingly consistent with recent surface force balance experimental measurements.

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