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

2003 ◽  
Vol 125 (4) ◽  
pp. 700-708 ◽  
Author(s):  
George G. Adams ◽  
Sinan Mu¨ftu¨ ◽  
Nazif Mohd Azhar
Keyword(s):  
Real Contact Area ◽  
Asperity Contact ◽  
Adhesion Forces ◽  
Friction Forces ◽  
Dugdale Model ◽  
The Real ◽  
Nano Scale ◽  
Macro Scale ◽  
Asperity Contacts ◽  
Coefficient Versus

As loading forces decrease in applications such as MEMS and NEMS devices, the size of the asperity contacts which comprise the real contact area tend to decrease into the nano scale regime. This reduction in size of the contacts is only partially offset by the nominally increased smoothness of these contacting surfaces. Because the friction force depends on the real area of contact, it is important to understand how the material and topographical properties of surfaces contribute to friction forces at this nano scale. In this investigation, the single asperity nano contact model of Hurtado and Kim is incorporated into a multi-asperity model for contact and friction which includes the effect of asperity adhesion forces using the Maugis-Dugdale model. The model spans the range from nano-scale to micro-scale to macro-scale contacts. Three key dimensionless parameters have been identified which represent combinations of surface roughness measures, Burgers vector length, surface energy, and elastic properties. Results are given for the friction coefficient versus normal force, the normal and friction forces versus separation, and the pull-off force for various values of these key parameters.

A Nano-Scale Multi-Asperity Contact and Friction Model

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

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.

Scale effects on the attachment pads and friction forces in syrphid flies (Diptera, Syrphidae)

2001 ◽  
Vol 204 (8) ◽  
pp. 1421-1431 ◽  
Author(s):  
S. Gorb ◽  
E. Gorb ◽  
V. Kastner
Keyword(s):  
Body Mass ◽  
Friction Force ◽  
Contact Area ◽  
Scale Effects ◽  
Real Contact Area ◽  
Resistance Force ◽  
Friction Forces ◽  
The Real ◽  
Frictional Properties ◽  
Real Contact

To test the role of constructional and dimensional factors in the generation of friction force by systems of setose attachment pads, six species of syrphid fly (Platycheirus angustatus, Sphaerophoria scripta, Episyrphus balteatus, Eristalis tenax, Myathropa florea and Volucella pellucens) were studied using light and scanning electron microscopy. Flies were selected according to their various body mass and attachment pad dimensions. Such variables as pad area, setal density, the area of a single setal tip and body mass were individually measured. A centrifugal force tester, equipped with a fibre-optic sensor, was used to measure the friction forces of the pads on a smooth horizontal surface made of polyvinylchloride. Friction force, which is the resistance force of the insect mass against the sum of centrifugal and tangential forces, was greater in heavier insects such as Er. tenax, M. florea and V. pellucens. Although lighter species generated lower frictional forces, the acceleration required to detach an insect was greater in smaller species. The area of attachment pads, setal tip area and setal density differed significantly in the species studied, and the dependence of these variables on body mass was significant. The frictional properties of the material of the setal tips were not dependent on the dimensions of the fly species. Similar results were obtained for the frictional properties of the pulvillus as a whole. Thus, the properties of the secretion and the mechanical properties of the material of the setal tips are approximately constant among the species studied. It is concluded that differences in friction force must be related mainly to variations in the real contact area generated by the pad on the smooth surface. The real contact area can be estimated as the summed area of the broadened setal tips of the pad in contact with the surface. The real contact area depends on such morphological variables as setal density and the area of a single setal tip. Although individual variables vary among flies with different dimensions, they usually compensate such that smaller setal tip area is partially compensated for by higher setal density.

Asperity-Based Models of Micro-Scale Friction

2005 ◽  
Author(s):  
George G. Adams
Keyword(s):  
Contact Area ◽  
Tangential Force ◽  
Scale Dependence ◽  
Real Contact Area ◽  
Nonlinear Load ◽  
Friction Forces ◽  
Micro Scale ◽  
Load Dependence ◽  
Real Contact ◽  
Asperity Contacts

As surfaces become smoother and loading forces decrease in applications such as MEMS, NEMS, and magnetic recording devices, the size and number of the asperity contacts which comprise the real contact area continues to decrease. The tangential force which is measured between two sliding bodies is the combined result of friction forces which are present in a very large number of nano and micro scale asperity contacts. Recent experiments as well as modeling have shown considerable scale-dependence and nonlinear load-dependence of the friction force. These models will be reviewed and discussed.

Simulation of Nanomanipulation Using Compliance-Based Contact Dynamics Modeling Technique

2007 ◽  
Author(s):  
Ou Ma ◽  
Xiumin Diao ◽  
Mingjun Zhang
Keyword(s):  
Contact Forces ◽  
Contact Dynamics ◽  
Modeling Technique ◽  
Published Data ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Friction Forces ◽  
Nano Scale ◽  
Model Fidelity ◽  
Macro Scale

This paper describes dynamics modeling and simulation of AFM-based manipulation of a nano-scale object using the compliance-based contact dynamics modeling technique (also referred to as the penalty method). Such a modeling technique has been well developed and widely applied in macro-scale applications. Its applicability to nano-scale cases is, however, relatively new and thus, requires more investigation. The dynamics model developed in the paper includes the Van der Waals forces, electrostatic forces, contact forces (for modeling repulsion), and friction forces with consideration of contact geometry, stiffness, and friction properties of all the physically interacting objects. The model can simulate the dynamic behavior of interactions between nano-scale objects and its environment. For demonstration, the dynamic simulation results of an AFM-based manipulation process are presented. To provide confidence of the model fidelity, a simulation example which matches some published data is presented.

scholarly journals Relationship between the real contact behavior and tribological characteristics of cotton fabric

Friction ◽  
2020 ◽  
Author(s):  
Rongxin Chen ◽  
Jiaxin Ye ◽  
Wei Zhang ◽  
Jiang Wei ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Contact Area ◽  
Dynamic Change ◽  
Tribological Characteristics ◽  
Real Contact Area ◽  
Cotton Fibers ◽  
Friction Behavior ◽  
Contact Behavior ◽  
The Real ◽  
Real Contact

Abstract The tribological characteristics of cotton fibers play an important role in engineering and materials science, and real contact behavior is a significant aspect in the friction behavior of cotton fibers. In this study, the tribological characteristics of cotton fibers and their relationship with the real contact behavior are investigated through reciprocating linear tribotesting and real contact analysis. Results show that the friction coefficient decreases with a general increase in load or velocity, and the load and velocity exhibit a co-influence on the friction coefficient. The dynamic change in the real contact area is recorded clearly during the experiments and corresponds to the fluctuations observed in the friction coefficient. Moreover, the friction coefficient is positively correlated with the real contact area based on a quantitative analysis of the evolution of friction behavior and the real contact area at different loads and velocities. This correlation is evident at low velocities and medium load.

An Observation Method of Real Contact Area during PVA Brush Scrubbing

2018 ◽  
Vol 282 ◽  
pp. 73-76 ◽  
Author(s):  
Toshiyuki Sanada ◽  
Masanao Hanai ◽  
Akira Fukunaga ◽  
Hirokuni Hiyama
Keyword(s):  
Contact Area ◽  
Contact Condition ◽  
Real Contact Area ◽  
Led Light ◽  
The Real ◽  
Real Contact ◽  
Observation Method

In the post CMP cleaning, the contact condition between PVA brush and surface is very important. In this study, we observed the real contact area between a brush and surface using a collimating LED light and prism. As a result, we found that the real contact area increases with increasing the brush compression. In addition, we also found that the real contact area decreases when the brush starts to move, and the brush was locally compressed due to its deformation.

Identifying Product Scaling Principles: A Tool for Bioinspired Design and Beyond

2011 ◽  
Author(s):  
Angel G. Perez ◽  
Julie S. Linsey
Keyword(s):  
Scaling Laws ◽  
Initial Step ◽  
Nano Scale ◽  
Bioinspired Design ◽  
Macro Scale ◽  
Design By Analogy ◽  
Global Principles ◽  
Physical Principles

There are countless products that perform the same function but are engineered to suit a different scale. Designers are often faced with the problem of taking a solution at one scale and mapping it to another. This frequently happens with design-by-analogy and bioinspired design. Despite various scaling laws for specific systems, there are no global principles for scaling systems, for example from a biological nano-scale to macro-scale. This is likely one of the reasons bioinspired design is difficult. Very often scaling laws assume the same physical principles are being used, but this study of products indicates that a variety of changes occur as scale changes, including changing the physical principles to meet a particular function. Empirical product research was used to determine a set of principles by observing and understanding numerous products to unearth new generalizations. The function a product performs is examined in various scales to view subtle and blatant differences. Principles are then determined. This study provides an initial step in creating new innovative designs based on existing solutions in nature or other products that occur at very different scales. Much further work is needed by studying additional products and bioinspired examples.

Electric Control of Friction on Silicon Studied by Atomic Force Microscope

NANO ◽  
2015 ◽  
Vol 10 (03) ◽  
pp. 1550038 ◽  
Author(s):  
Yan Jiang ◽  
Lili Yue ◽  
Boshen Yan ◽  
Xi Liu ◽  
Xiaofei Yang ◽  
...  
Keyword(s):  
Atomic Force Microscope ◽  
Bias Voltage ◽  
Electrostatic Force ◽  
Adhesion Forces ◽  
Friction Forces ◽  
Type Silicon ◽  
Atomic Force ◽  
Electric Control ◽  
Before And After ◽  
Track Line

We investigated friction on an n-type silicon surface using an atomic force microscope when a bias voltage was applied to the sample. Friction forces on the same track line were measured before and after the bias voltages were applied and it was found that the friction forces in n-type silicon can be tuned reversibly with the bias voltage. The dependence of adhesion forces between the silicon nitride tip and Si sample on the bias voltages approximately follows a parabolic law due to electrostatic force, which results in a significant increase in the friction force at an applied electric field.

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