scholarly journals On an Elastoplastic Sliding Model for a Coated Single Asperity

Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 96 ◽  
Author(s):  
Can Wang ◽  
Dik Schipper
Keyword(s):  
Elastic Modulus ◽  
Yield Strength ◽  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Contact Process ◽  
Friction Model ◽  
Contact Algorithm ◽  
Single Asperity ◽  
Asperity Contacts ◽  
Nanocrystalline Layer

In this study, a sliding friction model for coated single asperity contacts is proposed. A displacement-driven layered contact algorithm is firstly introduced and verified by the finite element method. Then, this algorithm is applied to simulate the contact between two semispherical asperities. The full sliding contact process is discretized into a series of transient steps, and each of these steps are calculated by the displacement-driven contact algorithm. The effects of the interference depth and the properties of, respectively, the tribofilm (thickness, elastic modulus, and yield strength) and the nanocrystalline layer on the sliding coefficient of friction are investigated. The results suggest that when surface adhesion and asperity damage are ignored, the plastic deformation of the tribofilm is the main source of the sliding friction. Greater interference depth, tribofilm with greater thickness, higher elastic modulus or lower yield strength, and the presence of a nanocrystalline layer will lead to a higher coefficient of friction in single asperity sliding.

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.

scholarly journals Densification of Ceramic Matrix Composite Preforms by Si2N2O Formed by Reaction of Si with SiO2 under High Nitrogen Pressure. Part 2: Materials Properties

2021 ◽  
Vol 5 (7) ◽  
pp. 179
Author(s):  
Brice Taillet ◽  
René Pailler ◽  
Francis Teyssandier
Keyword(s):  
Elastic Modulus ◽  
Yield Strength ◽  
Room Temperature ◽  
Outer Part ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Nitrogen Pressure ◽  
High Nitrogen ◽  
Yield Strain ◽  
High Nitrogen Pressure

Ceramic matrix composites (CMCs) have been prepared and optimized as already described in part I of this paper. The fibrous preform made of Hi-Nicalon S fibers was densified by a matrix composed of Si2N2O prepared inside the CMC by reacting a mixture of Si and SiO2 under high nitrogen pressure. This part describes the oxidation resistance and mechanical properties of the optimized CMC. The CMC submitted to oxidation in wet oxygen at 1400 °C for 170 h exhibited an oxidation gradient from the surface to almost the center of the sample. In the outer part of the sample, Si2N2O, Si3N4 and SiC were oxidized into silica in the cristobalite-crystallized form. The matrix microstructure looks similar to the original one at the center of the sample, while at the surface large pores are observed and the fiber/matrix interphase is consumed by oxidation. The elastic modulus and the hardness measured at room temperature by nano-indentation are, respectively, 100 and 8 GPa. The elastic modulus measured at room temperature by tensile tests ranges from 150 to 160 GPa and the ultimate yield strength from 320 to 390 MPa, which corresponds to a yield strain of about 0.6%. The yield strength identified by acoustic emission is about 40 MPa.

Materials characterization and effect of purity and ion implantation on the friction and wear of sublimed fullerene films

1994 ◽  
Vol 9 (11) ◽  
pp. 2823-2838 ◽  
Author(s):  
B.K. Gupta ◽  
Bharat Bhushan ◽  
C. Capp ◽  
J.V. Coe
Keyword(s):  
Fourier Transform ◽  
Elastic Modulus ◽  
Ion Implantation ◽  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Steel Ball ◽  
Scanning Tunneling ◽  
High Dose ◽  
Wear Life ◽  
Plastic Deformation Behavior

In previous studies, sublimed C60-rich fullerene films on silicon, when slid against a 52100 steel ball under dry conditions, have exhibited low coefficient of friction (∼0.12). Films with different purities can be produced by sublimation at different substrate temperatures. In this paper, effects of purity of fullerene films and ion implantation of the films with Ar ions on the friction and wear properties of sublimed fullerene films are reported. C60-rich films (called here films with high purity) exhibit low macroscale friction. An increased amount of C70 and impurities in the fullerene film determined using Raman and Fourier transform infrared (FTIR), increases its coefficient of friction. Microscale friction measurements using friction force microscopy also exhibited similar trends. Low coefficient of friction of sublimed C60-rich films on silicon is probably due to the formation of a tenacious transfer film of C60 molecules on the mating 52100 steel ball surface. Based on scanning tunneling microscopy (STM), transmission electron microscopy (TEM), and high resolution TEM (HRTEM), we found that fullerene films primarily consisted of C60 molecules in a fcc lattice structure. Nanoindenter was used to measure hardness and elastic modulus of the as-deposited films. Ion-implantation with 1 × 1016 Ar+ cm−2 reduced macroscale friction down to about 0.10 from 0.12 with an increase in wear life by a factor of 4; however, doses of 5 × 1016 ions cm−2 gave three times higher friction and poorer wear life; higher doses disintegrated the C60 molecules. Based on STM, TEM, Raman, FTIR, and laser desorption Fourier-transform ion cyclotron resonance mass spectrometer (LD/FT/ICR) studies, we found that the ion implantation with a dose of 1 × 1016 Ar+ cm−2 resulted in smoothening of the fullerene film surface probably by compacting clusters, but without disintegrating the C60 molecules. However, a high dose of 5 × 1016 Ar+ cm−2 damaged the C60 molecules, converting it to an amorphous carbon. Nanoindentation studies show that ion implantation with a dose of 1 × 1016 Ar+ cm−2 resulted in an increase in the hardness from about 1.2 to 4.0 GPa and in elastic modulus from about 70 to 75 GPa and modified the elastic-plastic deformation behavior.

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 Solid Lubrication by Multiwalled Carbon Nanotubes in Air and in Vacuum for Space and Aeronautics Applications

2005 ◽  
Author(s):  
K. Miyoshi ◽  
K. W. Street ◽  
R. L. Vander Wal ◽  
R. Andrews ◽  
David Jacques ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Solid Lubrication ◽  
Multiwalled Carbon ◽  
Solid Lubrication Friction ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Steel Balls

To evaluate recently developed aligned multiwalled carbon nanotubes (MWNTs) and dispersed MWNTs for solid lubrication applications, unidirectional sliding friction experiments were conducted with 440C stainless steel balls and hemispherical alumina-yttria stabilized zirconia pins in sliding contact with the MWNTs deposited on quartz disks in air and in vacuum. The results indicate that MWNTs have superior solid lubrication friction properties and endurance lives in air and vacuum under dry conditions. The coefficient of friction of the dispersed MWNTs is close to 0.05 and 0.009 in air and in vacuum, respectively, showing good dry lubricating ability. The wear life of MWNTs exceeds 1 million passes in both air and vacuum showing good durability. In general, the low coefficient of friction can be attributed to the combination of the transferred, agglomerated patches of MWNTs on the counterpart ball or pin surfaces and the presence of tubular MWNTs at interfaces.

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.

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