scholarly journals Experimental Studies of Nanometer-Scaled Single-Asperity Contacts with Metal Surfaces

2018 ◽  
Author(s):  
Arnaud Caron
Keyword(s):  
Metal Surfaces ◽  
Experimental Studies ◽  
Single Asperity ◽  
Asperity Contacts

scholarly journals The sliding contact of a rigid wavy surface with a viscoelastic half-space

2014 ◽  
Vol 470 (2169) ◽  
pp. 20140392 ◽  
Author(s):  
N. Menga ◽  
C. Putignano ◽  
G. Carbone ◽  
G. P. Demelio
Keyword(s):  
Half Space ◽  
Applied Load ◽  
Sliding Velocity ◽  
Contact Conditions ◽  
Frictional Properties ◽  
Single Asperity ◽  
Partial Contact ◽  
Pressure Distributions ◽  
Full Contact ◽  
Asperity Contacts

In this paper, the contact of a rigid sinusoid sliding on a viscoelastic half-space is studied. The solution of the problem is obtained by following the path drawn by Hunter for cylindrical contacts. Results show that depending on the remote applied load, a transition from full contact conditions to partial contact may occur depending on the sliding velocity. This effect, which is not observed in smooth single asperity contacts, is related to the viscoelastic stiffening of the material and to the periodicity of the contacts. Frictional properties as well as contact area, displacement and pressure distributions are discussed in detail.

scholarly journals Calculation of the Optimum Cone Angle of a Confuser Used for Reversive-Jet Cleaning of Metal Surfaces against Corrosion

2019 ◽  
Vol 18 (3) ◽  
pp. 216-222
Author(s):  
I. V. Kachanov ◽  
A. N. Zhuk ◽  
I. M. Shatalov ◽  
V. V. Veremenyuk ◽  
A. V. Filipchik
Keyword(s):  
Metal Surfaces ◽  
Production Efficiency ◽  
Cone Angle ◽  
Experimental Studies ◽  
Raw Material ◽  
Flame Spraying ◽  
Working Fluid ◽  
Material Base ◽  
River Sand ◽  
Jet Impact

The modern industrial production of the Republic of Belarus is characterized by the absence of its own raw material base and significant dependence on imported energy carriers and material resources supplied at world prices. When working in such conditions, production efficiency can be achieved through all-round economy and creation of modern energyand resource-saving technologies. However implementation of such technologies, for example, laser cutting and welding, cladding, flame spraying, painting, etc. directly depends on quality of cleaning metal surfaces from corrosion. Theoretical and experimental studies conducted at the Department of Shipbuilding and Hydraulics of the Belarusian National Technical University have shown that it is very economical to remove corrosion products from metal surfaces using new technology of reverse jet cleaning. The reverse jet cleaning technology is based on a physical principle which presupposes that a jet of working fluid (pulp based on river sand or bentonite clay) rotates 180º when it hits the surface to be cleaned and it leads to an increase in jet impact on the surface to be cleaned by 1.5–2 times due to occurrence of a reactive component. In order to ensure a marked jet reversal an original case design has been developed which is characterized by a patent novelty. One of the main elements in this design is a confuser-shaped stream-forming device. Theoretical investigations on pressure losses of working fluid in a confuser channel which are based on the study of functional at the extremum have made it possible to obtain a dependence for calculation of an optimal cone angle at a turbulent mode of motion within the range of Reynolds numbers 4000 < Re < 3 ×106 while taking into account an influence of working fluid density, its dynamic or kinematic viscosity, average velocity movement of working fluid, confuser radii.

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.

A Nano-Scale Multi-Asperity Model for Contact and Friction

2002 ◽  
Author(s):  
George G. Adams ◽  
Sinan Mu¨ftu¨ ◽  
Nazif Mohd Azhar
Keyword(s):  
Normal Force ◽  
Real Contact Area ◽  
Adhesion Forces ◽  
Friction Forces ◽  
Dugdale Model ◽  
Single Asperity ◽  
Nano Scale ◽  
Macro Scale ◽  
Asperity Contacts ◽  
Asperity Model

As surfaces become smoother and loading forces decrease in applications such as MEMS and NEMS devices, the asperity contacts which comprise the real contact area will continue to decrease into the nano scale regime. Thus it becomes important to understand how the material and topographical properties of surfaces contribute to measured friction forces at this nano scale. We have incorporated the single asperity nano contact model of Hurtado and Kim into a multi-asperity model for contact and friction which includes the effect of asperity adhesion forces using the Maugis-Dugdale model. Our model spans the range from nano-scale to micro-scale to macro-scale contacts. We have identified three key dimensionless parameters representing combinations of surface roughness measures, Burgers vector length, surface energy, and elastic modulus. Results are given for the normal and friction forces vs. separation, and for the friction coefficient vs. normal force for various values of these key parameters.

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