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).

AFM Interaction Forces of Lubricity Materials Surface

2012 ◽  
Vol 528 ◽  
pp. 95-98
Author(s):  
Xue Feng Li ◽  
Chu Wu ◽  
Shao Xian Peng ◽  
Jian Li
Keyword(s):  
Atomic Force Microscopy ◽  
Friction Force ◽  
Sliding Friction ◽  
Static Friction ◽  
Adhesive Force ◽  
New Method ◽  
Interaction Forces ◽  
Scanning Angle ◽  
Force Microscopy ◽  
Atomic Force

Micro interaction forces of lubricity surface of silicon and mica were studied using atomic force microscopy (AFM). From different scanning angle and bisection distance of the AFM, a new method of measuring micro static friction of lubricity surface materials was investigated. Results show that the micro coefficients of static and sliding friction of mica are less than the silicon, but the adhesive force is bigger. The mechanism of friction force of the two lubricity materials was discussed.

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.

Collision of two coins on a horizontal surface

2021 ◽  
Vol 57 (1) ◽  
pp. 015009
Author(s):  
Rod Cross
Keyword(s):  
Friction Force ◽  
Sliding Friction ◽  
Static Friction ◽  
Video Camera ◽  
Horizontal Surface ◽  
Collision Process ◽  
Oblique Angle ◽  
Billiard Ball ◽  
Air Table

Abstract Oblique angle collisions of two penny coins on a smooth, horizontal surface were filmed with a video camera to investigate the physics of the collision process. If one of the coins is initially at rest, then the two coins emerge approximately at right angles, as commonly observed in billiard ball collisions and in puck collisions on an air table. The coins actually emerged at an angle less than 90 degrees due to friction between the coins, which also resulted in both coins rotating after the collision. At glancing angles, the friction force was due to sliding friction. At other angles of incidence the coins gripped each other and the friction force was then due to static friction.

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.

Static Friction and the Law of Rubber Friction

1963 ◽  
Vol 36 (2) ◽  
pp. 365-376 ◽  
Author(s):  
V. V. Lavrentev
Keyword(s):  
Friction Force ◽  
Contact Time ◽  
Sliding Friction ◽  
Tangential Force ◽  
Static Friction ◽  
Experimental Results ◽  
The Other ◽  
Chemical Bonds ◽  
Vulcanized Rubber ◽  
Rubber Friction

Abstract a) The true static friction of vulcanized rubber is in practice immeasurably small (equal to zero, according to theory). b) The static friction as usually determined is an initial friction force. c) The initial friction force is equal to the sliding friction force in accelerated movement. It depends on the contact time, the rate of growth of the tangential force and the other conditions of experiment. d) With long contact times, particularly at higher temperatures, strong chemical bonds are formed between the vulcanized rubber and the track, leading to true static friction. e) The theoretical law of friction agrees well with the experimental results over the whole range of normal pressures. f) Good approximations are given in the range of low normal pressures by Coulomb's law (5) and in the rubber of high normal pressures by that of Thirion (7).

scholarly journals Friction force microscopy of tribochemistry and interfacial ageing for the SiO x /Si/Au system

2018 ◽  
Vol 9 ◽  
pp. 1647-1658 ◽  
Author(s):  
Christiane Petzold ◽  
Marcus Koch ◽  
Roland Bennewitz
Keyword(s):  
Friction Force ◽  
Static Friction ◽  
Chemical Bonds ◽  
Friction Force Microscopy ◽  
Adhesion Forces ◽  
Low Friction ◽  
Friction Forces ◽  
Force Microscopy ◽  
Static Contact ◽  
Wear Friction

Friction force microscopy was performed with oxidized or gold-coated silicon tips sliding on Au(111) or oxidized Si(100) surfaces in ultrahigh vacuum. We measured very low friction forces compared to adhesion forces and found a modulation of lateral forces reflecting the atomic structure of the surfaces. Holding the force-microscopy tip stationary for some time did not lead to an increase in static friction, i.e., no contact ageing was observed for these pairs of tip and surface. Passivating layers from tip or surface were removed in order to allow for contact ageing through the development of chemical bonds in the static contact. After removal of the passivating layers, tribochemical reactions resulted in strong friction forces and tip wear. Friction, wear, and the re-passivation by oxides are discussed based on results for the temporal development of friction forces, on images of the scanned area after friction force microscopy experiments, and on electron microscopy of the tips.

scholarly journals Highly Selective Biomimetic Flexible Tactile Sensor for Neuroprosthetics

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Yue Li ◽  
Zhiguang Cao ◽  
Tie Li ◽  
Fuqin Sun ◽  
Yuanyuan Bai ◽  
...  
Keyword(s):  
Friction Force ◽  
Sliding Friction ◽  
Dielectric Material ◽  
Silver Nanowires ◽  
Static Friction ◽  
Tactile Sensor ◽  
Capacitive Sensor ◽  
Silver Nanowire ◽  
Friction Forces ◽  
Signal Encoding

Biomimetic flexible tactile sensors endow prosthetics with the ability to manipulate objects, similar to human hands. However, it is still a great challenge to selectively respond to static and sliding friction forces, which is crucial tactile information relevant to the perception of weight and slippage during grasps. Here, inspired by the structure of fingerprints and the selective response of Ruffini endings to friction forces, we developed a biomimetic flexible capacitive sensor to selectively detect static and sliding friction forces. The sensor is designed as a novel plane-parallel capacitor, in which silver nanowire–3D polydimethylsiloxane (PDMS) electrodes are placed in a spiral configuration and set perpendicular to the substrate. Silver nanowires are uniformly distributed on the surfaces of 3D polydimethylsiloxane microcolumns, and silicon rubber (Ecoflex®) acts as the dielectric material. The capacitance of the sensor remains nearly constant under different applied normal forces but increases with the static friction force and decreases when sliding occurs. Furthermore, aiming at the slippage perception of neuroprosthetics, a custom-designed signal encoding circuit was designed to transform the capacitance signal into a bionic pulsed signal modulated by the applied sliding friction force. Test results demonstrate the great potential of the novel biomimetic flexible sensors with directional and dynamic sensitivity of haptic force for smart neuroprosthetics.

Drift Turning of Lateral Guided Vehicle With Sensor Steering Mechanism: Variable Kinetic Friction Model

2005 ◽  
Author(s):  
Yoshihiro Takita ◽  
Hisashi Date
Keyword(s):  
Friction Force ◽  
Coulomb Friction ◽  
High Speed ◽  
Static Friction ◽  
Friction Model ◽  
Tire Model ◽  
Kinetic Friction ◽  
Steering Mechanism ◽  
Three Stages ◽  
Coulomb Friction Model

In a previous paper, the simulated loci of high-speed cornering did not correspond with experimentally obtained results because the tire model used only the sticking in the Coulomb friction model. If the centrifugal force becomes larger than the cornering force of the tires, then the vehicle does not maintain the desired course. The cornering force is affected by the sticking or slipping condition of the tires. In order to simulate the high-speed cornering trajectory, the present paper assumes three stages of friction: low kinetic friction force at the beginning of slipping, the period of kinetic friction force, and the return to the static friction condition at small slip angles. In addition to the Rear motor Rear drive (RR) type vehicle, the Front motor Front drive (FF) type vehicle with a Sensor Steering Mechanism (SSM) and a 4-wheel steering mechanism is developed. In the experiments of present paper, both of these robots are run on an oval course at high speed. Numerical simulation and experimental results indicate effective prediction by the friction model.

Analytical Dynamics of a Piecewise Linear Friction Oscillator Under a Periodic Excitation

2005 ◽  
Author(s):  
Albert C. J. Luo ◽  
Patrick Zweigart
Keyword(s):  
Friction Force ◽  
Piecewise Linear ◽  
Static Friction ◽  
Friction Model ◽  
Analytical Dynamics ◽  
Periodic Motions ◽  
Input And Output ◽  
Output Force ◽  
Linear Friction ◽  
Friction Oscillator

This paper presented a methodology to determine the analytical dynamics of the periodically forced friction oscillator. The friction force is modeled by a piecewise linear, kinetic friction model with the static force. The input and output force concepts in the vicinity of the discontinuous friction force boundary are introduced. The force criteria for the onset and vanishing of stick and non-stick motions are presented through the input and output forces. The periodic motion of such an oscillator is determined through the corresponding mapping structure. The local stability of the periodic motions is presented. Illustrations of the periodic motions in such a piecewise friction model are given for better understanding the stick motion with static friction. The force responses are presented, which agreed very well with the force criteria.

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