Numerical Investigation of Atomic Scale Kinetic Friction in Ambient Condition With a Novel Extended Prandtl-Tomlinson Model

2014 ◽  
Author(s):  
Birahima Gueye ◽  
Chenfei Sun ◽  
Yan Zhang ◽  
Yujuan Wang ◽  
Yunfei Chen
Keyword(s):  
Relative Humidity ◽  
Adhesion Force ◽  
Normal Load ◽  
Analytical Data ◽  
Two Dimensions ◽  
Atomic Scale ◽  
Kinetic Friction ◽  
Capillary Bridge ◽  
Mode Operation ◽  
Tomlinson Model

A more adequate extended Prandtl-Tomlinson model in two dimensions (2D) analysis is proposed in the aim to thoroughly investigate the interplay between kinetic friction, relative humidity (RH), normal load, and temperature in both contact and tapping mode atomic force microscopic (AFM). In contact mode operation, results firstly show that for various applied normal loads highly wetted surface in contrast to partially wetted surface exhibits lower friction at finite temperature range. This phenomenon is attributed to the film layer acting as a lubricant. Secondly, two different regimes when varying the relative humidity were further observed with increasing temperature. The first one shows the thermolubricity’s effect at low RH (RH 20%) while the second regime remarkably confirms an increase of friction with temperature at higher RH (RH60%) which is inconsistent with common observation. The latter regime is characterized by the thermally activated capillary bridge formation leading to an increase of the total adhesion force. Thirdly we demonstrated that both regimes also hold in ac mode operation and regardless to the humidity level, either low or high RH, friction force decreases with increasing amplitude modulation. Good agreement was found with measurement and analytical data reported previously. In the model treatment, however, only effects of capillary force which dominate in AFM measurement were considered.

scholarly journals The description of friction of silicon MEMS with surface roughness: virtues and limitations of a stochastic Prandtl–Tomlinson model and the simulation of vibration-induced friction reduction

2010 ◽  
Vol 1 ◽  
pp. 163-171 ◽  
Author(s):  
W Merlijn van Spengen ◽  
Viviane Turq ◽  
Joost W M Frenken
Keyword(s):  
Surface Roughness ◽  
Critical Role ◽  
Measurement Data ◽  
Friction Model ◽  
Friction Reduction ◽  
Atomic Scale ◽  
Mems Devices ◽  
Tomlinson Model ◽  
Atomic Force ◽  
On Chip

We have replaced the periodic Prandtl–Tomlinson model with an atomic-scale friction model with a random roughness term describing the surface roughness of micro-electromechanical systems (MEMS) devices with sliding surfaces. This new model is shown to exhibit the same features as previously reported experimental MEMS friction loop data. The correlation function of the surface roughness is shown to play a critical role in the modelling. It is experimentally obtained by probing the sidewall surfaces of a MEMS device flipped upright in on-chip hinges with an AFM (atomic force microscope). The addition of a modulation term to the model allows us to also simulate the effect of vibration-induced friction reduction (normal-force modulation), as a function of both vibration amplitude and frequency. The results obtained agree very well with measurement data reported previously.

Atomistic Origins of Friction

2019 ◽  
pp. 348-388
Author(s):  
C. Mathew Mate ◽  
Robert W. Carpick
Keyword(s):  
Atomic Structure ◽  
Real Life ◽  
Static Friction ◽  
Electronic Excitations ◽  
Kinetic Friction ◽  
Dynamic Simulations ◽  
Tomlinson Model ◽  
Current State ◽  
Friction Models ◽  
Kontorova Model

This chapter covers the current state of knowledge about how the shear strength (the force needed to slide one surface over another) originates at the atomic level. For adhesive friction, friction originates from the forces needed to move the atoms on one surface over the atomic structure of the opposing surface; the simplest model for adhesive friction is the cobblestone model. The Frenkel–Kontorova model, the Prandtl–Tomlinson model, and molecular dynamic simulations are typically used to show how the atomic structure of the surfaces leads to static friction. One exciting aspect of these friction models is the prediction of superlubricity or negligible friction for incommensurate sliding surfaces, which is now being realized in experiments. Also discussed is why superlubricity is not observed in real-life situations. As atoms and molecules slide over surfaces, kinetic friction originates from phonon and electronic excitations, which are typically studied using the quartz crystal microbalance (QCM).

Friction Characteristics and Adhesion Force Under Low Normal Load

1995 ◽  
Vol 117 (4) ◽  
pp. 569-574 ◽  
Author(s):  
Yasuhisa Ando ◽  
Yuichi Ishikawa ◽  
Tokio Kitahara
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Adhesion Force ◽  
Normal Load ◽  
Adhesion Forces ◽  
Test Pieces ◽  
Before And After ◽  
Constant Normal Load ◽  
The Mean ◽  
Steel Balls

The friction coefficient and adhesion force between steel balls and flat test pieces were measured during friction under low normal load in order to examine the tribological characteristics. First, the friction coefficients were measured under a constant normal load of 0.8 to 2350 μN, and the adhesion forces were measured before and after each friction. The result showed that the friction coefficient was highest at low normal loads, while the friction force divided by the sum of the normal load and the mean adhesion force was almost constant over the whole range of loads. Second, when the normal load was reduced gradually during friction, friction still acted when the normal load became negative and a pulling off force was applied to the surface. Thus an adhesion force acts during friction and this adhesion force affects the friction force in the same way as the normal load.

Scale-dependent nanomechanical behavior and anisotropic friction of nanotextured silicon surfaces

2009 ◽  
Vol 24 (10) ◽  
pp. 3038-3043 ◽  
Author(s):  
Hanshen Zhang ◽  
Kyriakos Komvopoulos
Keyword(s):  
Sliding Friction ◽  
Adhesion Force ◽  
Normal Load ◽  
Ion Beam ◽  
Strong Dependence ◽  
Surface Texturing ◽  
Surface Force ◽  
Silicon Surfaces ◽  
Real Contact Area ◽  
Ripple Orientation

Nanoscale surface texturing of silicon was accomplished by oblique Ar+ ion beam irradiation. Atomic force microscope (AFM) imaging showed that nanotexturing produced an anisotropic morphology consisting of ordered nanometer-sized ripples. Surface force microscope (SFM) measurements showed that the nanotextured surface exhibited scale-dependent nanomechanical behavior during indentation loading/unloading and anisotropic sliding friction, significantly different from those of the original (untextured) surface. AFM and SFM results showed a strong dependence of the nanoindentation response and friction coefficient on the tip radius and sliding direction relative to the ripple orientation. The observed experimental trends are interpreted in terms of the applied normal load, real contact area, interfacial adhesion force, tip-ripple interaction scale, and ripple orientation.

THE EFFECT OF SURFACE TEXTURE OF STEEL DISC ON FRICTION AND FRETTING WEAR

Tribologia ◽  
2018 ◽  
Vol 280 (4) ◽  
pp. 39-48 ◽  
Author(s):  
Agnieszka LENART ◽  
Paweł PAWLUS ◽  
Andrzej DZIERWA ◽  
Mirosław TUPAJ
Keyword(s):  
Relative Humidity ◽  
Surface Texture ◽  
Normal Load ◽  
Fretting Wear ◽  
Surface Textures ◽  
Steel Disc ◽  
42Crmo4 Steel ◽  
Number Of Cycles ◽  
Effect Of Surface

Fretting tests were performed using an Optimol SRV5 tribotester in a ball-on-flat scheme. Balls from 100Cr6 steel of 60 HRC hardness and diameters of 10 mm co-acted with discs from 42CrMo4 steel of 47 HRC hardness under dry gross fretting conditions. Tests were performed at 300C and 25–35% relative humidity, and the number of cycles was 18000. During each test, the normal load was kept constant. Six sets of experiments were conducted. Discs had different surface textures as the result of machining. It was found that the lowest coefficients of friction were obtained for anisotropic surfaces when ball movements were perpendicular to main disc texture directions.

Dry Adhesion Based on Electrospun Polymer Nanofibers

2010 ◽  
Author(s):  
Qiang Shi ◽  
Shing-Chung Wong ◽  
Kai-Tak Wan ◽  
Todd A. Blackledge ◽  
John Najem
Keyword(s):  
Relative Humidity ◽  
Linear Relationship ◽  
Contact Mechanics ◽  
Adhesion Force ◽  
Van Der Waals ◽  
Polymer Nanofibers ◽  
Mechanics Model ◽  
Tensile Tester ◽  
Dry Adhesion ◽  
Fiber Radius

Dry Adhesion exists between polymer nano/microfibers. An elaborate experiment was performed to directly measure the adhesion between electrospun poly(ε-caprolactone) (PCL) microfibers using a nano force tensile tester. Electrospun nano/microfibers with radius ranging from 0.2 to 1.1 μm were investigated. It was found that the adhesion force depended on the fiber radius following a linear relationship, which complied with the classical Johnson-Kendall-Roberts (JKR) contact mechanics model. The force increased with temperature and decreased with relative humidity between two fibers positioned in orthogonal directions. Our data suggested the van der Waals’ (vdW) interactions are primarily operative between the micro-/nano-fibers.

Spontaneous atomic-scale magnetic skyrmion lattice in two dimensions

2011 ◽  
Vol 7 (9) ◽  
pp. 713-718 ◽  
Author(s):  
Stefan Heinze ◽  
Kirsten von Bergmann ◽  
Matthias Menzel ◽  
Jens Brede ◽  
André Kubetzka ◽  
...  
Keyword(s):  
Two Dimensions ◽  
Atomic Scale
Sign in / Sign up

Export Citation Format

Share Document