Static Friction Model of Elastic-Plastic Contact Behavior of Surface With Elliptical Asperities

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Yeau-Ren Jeng ◽  
Shin-Rung Peng
Keyword(s):  
Shear Strength ◽  
Friction Coefficient ◽  
Contact Area ◽  
Static Friction ◽  
Friction Model ◽  
Effective Radius ◽  
Radius Ratio ◽  
Plasticity Index ◽  
Real Contact Area ◽  
Contact Mode

The friction coefficient (μ) of a contact surface with elliptical asperities is examined at various values of the plasticity index (ψ), the effective radius ratio (γ), the shear-strength-pressure proportionality constant (c), and the dimensionless limiting interfacial shear strength (τ¯m). The results demonstrate that the friction coefficient of the contact system increases with an increasing value of γ but decreases with an increasing value of ψ. Furthermore, it is shown that Amonton’s law is applicable for contact systems with either a low ψ and a high τ¯m or a high ψ and a low τ¯m. Analyzing the ratio of the nonelastic contact area, it is found that the asperities of a surface characterized by a large γ generally deform elastically at all values of the plasticity index, while those of a surface with a larger c deform plastically, particularly for surfaces with higher values of τ¯m and ψ. Finally, an inspection of the critical dimensionless real contact area shows that the contact mode of the surface is determined primarily by the value of the effective radius ratio.

On Slip Inception and Static Friction for Smooth Dry Contact

2014 ◽  
Vol 81 (12) ◽  
Author(s):  
Xi Shi
Keyword(s):  
Shear Strength ◽  
Contact Area ◽  
Material Properties ◽  
Static Friction ◽  
Friction Model ◽  
Interfacial Bonding ◽  
The Other ◽  
Material Failure ◽  
Bonding Failure ◽  
Dry Contact

Slip inception mechanism is very important for modeling of static friction and understanding of some experimental observations of friction. In this work, slip inception was treated as a local competence of interfacial bonding failure and weaker material failure. At any contacting point, if bond shear strength is weaker than softer material shear strength, slip inception is governed by interfacial bonding failure. Otherwise, it is governed by softer material failure. Considering the possible co-existence of these two slip inception mechanisms during presliding, a hybrid static friction model for smooth dry contact was proposed, which indicates that the static friction consists of two components: one contributed by contact area where bonding failure is dominant and the other contributed by contact area where material failure is dominant. With the proposed static friction model, the effects of contact pressure, the material properties, and the contact geometry on static friction were discussed.

A Static Friction Model for Elastic-Plastic Contacting Rough Surfaces

2004 ◽  
Vol 126 (1) ◽  
pp. 34-40 ◽  
Author(s):  
Lior Kogut ◽  
Izhak Etsion
Keyword(s):  
Friction Coefficient ◽  
Rough Surfaces ◽  
Static Friction ◽  
Friction Model ◽  
Plasticity Index ◽  
High Plasticity ◽  
Elastic Plastic ◽  
Static Friction Coefficient ◽  
Contact Adhesion ◽  
Limiting Case

A model that predicts the static friction for elastic-plastic contact of rough surfaces is presented. The model incorporates the results of accurate finite element analyses for the elastic-plastic contact, adhesion and sliding inception of a single asperity in a statistical representation of surface roughness. The model shows strong effect of the external force and nominal contact area on the static friction coefficient in contrast to the classical laws of friction. It also shows that the main dimensionless parameters affecting the static friction coefficient are the plasticity index and adhesion parameter. The effect of adhesion on the static friction is discussed and found to be negligible at plasticity index values larger than 2. It is shown that the classical laws of friction are a limiting case of the present more general solution and are adequate only for high plasticity index and negligible adhesion. Some potential limitations of the present model are also discussed pointing to possible improvements. A comparison of the present results with those obtained from an approximate CEB friction model shows substantial differences, with the latter severely underestimating the static friction coefficient.

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.

Strongly Anisotropic Rough Surfaces

1979 ◽  
Vol 101 (1) ◽  
pp. 15-20 ◽  
Author(s):  
A. W. Bush ◽  
R. D. Gibson ◽  
G. P. Keogh
Keyword(s):  
Random Process ◽  
Rough Surface ◽  
Contact Area ◽  
Process Model ◽  
Rough Surfaces ◽  
Plasticity Index ◽  
Real Contact Area ◽  
Elastic Contact ◽  
Elastic Plastic ◽  
Real Contact

The statistics of a strongly anisotropic rough surface are briefly described. The elastic contact of rough surfaces is treated by approximating the summits of a random process model by parabolic ellipsoids and applying the Hertzian solution for their deformation. Load and real contact area are derived as functions of the separation and for all separations the load is found to be approximately proportional to the contact area. The limits of elastic/plastic contact are discussed in terms of the plasticity index.

scholarly journals Evolution of real contact area under shear and the value of static friction of soft materials

2018 ◽  
Vol 115 (3) ◽  
pp. 471-476 ◽  
Author(s):  
R. Sahli ◽  
G. Pallares ◽  
C. Ducottet ◽  
I. E. Ben Ali ◽  
S. Al Akhrass ◽  
...  
Keyword(s):  
Contact Area ◽  
Normal Load ◽  
Scaling Law ◽  
Reduction Rate ◽  
Static Friction ◽  
Soft Materials ◽  
Real Contact Area ◽  
The Real ◽  
Real Contact ◽  
Area Reduction

The frictional properties of a rough contact interface are controlled by its area of real contact, the dynamical variations of which underlie our modern understanding of the ubiquitous rate-and-state friction law. In particular, the real contact area is proportional to the normal load, slowly increases at rest through aging, and drops at slip inception. Here, through direct measurements on various contacts involving elastomers or human fingertips, we show that the real contact area also decreases under shear, with reductions as large as 30%, starting well before macroscopic sliding. All data are captured by a single reduction law enabling excellent predictions of the static friction force. In elastomers, the area-reduction rate of individual contacts obeys a scaling law valid from micrometer-sized junctions in rough contacts to millimeter-sized smooth sphere/plane contacts. For the class of soft materials used here, our results should motivate first-order improvements of current contact mechanics models and prompt reinterpretation of the rate-and-state parameters.

scholarly journals Critical shoe contact area ratio for sliding on a tennis hard court

2017 ◽  
Vol 232 (2) ◽  
pp. 112-121 ◽  
Author(s):  
John Eric Goff ◽  
Luke Boswell ◽  
Daniel Ura ◽  
Mark Kozy ◽  
Matt J Carré
Keyword(s):  
Friction Coefficient ◽  
Contact Area ◽  
Sliding Friction ◽  
Static Friction ◽  
Area Ratio ◽  
Critical Ratio ◽  
Static Friction Coefficient ◽  
The Creation ◽  
Contact Area Ratio

Dimples have been used in the design of some modern tennis shoe outsoles to enhance sliding ability on hard courts. Experiments were performed with bespoke rubber samples possessing various numbers of holes, which served to simulate dimples in tennis shoe treads. The aim of the research was to assess the effect of contact area on sliding friction. As the ratio of holes to solid rubber increased, a critical ratio was reached whereby the static friction coefficient decreased by more than 11% for tread-to-court pressures comparable to real tennis play. Although this study analyzed bespoke rubber samples and not actual tennis shoe treads, shoe manufacturers should be interested in the existence of a critical dimple ratio that could aid them in the creation of tennis shoes suited for sliding on hard courts.

scholarly journals Rate-, state-, and pressure-dependent friction model based on the elastoplastic theory

Friction ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 768-783 ◽  
Author(s):  
Shingo Ozaki ◽  
Takeru Matsuura ◽  
Satoru Maegawa
Keyword(s):  
Friction Force ◽  
Contact Area ◽  
Contact Surface ◽  
Internal State ◽  
Friction Model ◽  
Real Contact Area ◽  
State Variables ◽  
Real Contact ◽  
Model Based ◽  
Acrylic Plate

AbstractAdhesion is one of essences with respect to rubber friction because the magnitude of the friction force is closely related to the magnitude of adhesion on a real contact area. However, the real contact area during sliding depends on the state and history of the contact surface. Therefore, the friction force occasionally exhibits rate-, state-, and pressure dependency. In this study, to rationally describe friction and simulate boundary value problems, a rate-, state-, and pressure-dependent friction model based on the elastoplastic theory was formulated. First, the evolution law for the friction coefficient was prescribed. Next, a nonlinear sliding surface (frictional criterion) was adopted, and several other evolution laws for internal state variables were prescribed. Subsequently, the typical response characteristics of the proposed friction model were demonstrated, and its validity was verified by comparing the obtained results with those of experiments conducted considering the contact surface between a rough rubber hemisphere and smooth acrylic plate.

Static Friction Model for Rough Surfaces With Asymmetric Distribution of Asperity Heights

2004 ◽  
Vol 126 (3) ◽  
pp. 626-629 ◽  
Author(s):  
Ning Yu, ◽  
Shaun R. Pergande, and ◽  
Andreas A. Polycarpou
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Static Friction ◽  
Friction Model ◽  
Published Data ◽  
Asymmetric Distribution ◽  
Adhesion Forces ◽  
Normal Contact ◽  
Static Friction Coefficient ◽  
Gaussian Case

The CEB static friction model is extended to include asymmetric distributions of asperity heights, using the normalized one-parameter Weibull distribution. The normal contact, tangential (friction), and adhesion forces are calculated for different skewness values, and are used to obtain the static friction coefficient. It is predicted that surfaces with negative skewness experience higher static friction coefficient compared to the Gaussian case, under the same external normal load, which agrees with published data. This effect is magnified for lower external loads, as is commonly encountered in microtribological applications.

The Effect of Tip Materials on the Nanotribology with Atomic Force Microscope Technique

2015 ◽  
Vol 723 ◽  
pp. 763-768
Author(s):  
Mei Dong ◽  
Mei Li ◽  
Yan Zhang
Keyword(s):  
Silicon Nitride ◽  
Friction Coefficient ◽  
Silicon Substrate ◽  
Normal Force ◽  
Real Contact Area ◽  
Wafer Surface ◽  
Contact Mode ◽  
Atomic Force ◽  
Microscope Technique ◽  
The Relationship

The effect of tip materials on the friction properties of silicon substrate was investigated by using atomic force microcopy (AFM). The roughness of the silicon wafer surface was characterized with silicon tip at tapping mode, and then the relationship between the friction force and normal force was obtained by silicon tip and silicon nitride tip at contact mode. The experimental results show that when the load exceeds a critical value, the friction coefficient with silicon tip increases from 0.17 to 0.37, which is due to the wear of the silicon tip; the friction coefficient with a hard silicon nitride tip increases from 0.25 to 0.5, which can only be attributed to the plastic deformation of silicon substrate. And the roughness of the silicon substrate can lead to an incomplete contact, which can influence the real contact area between the silicon nitride tip and silicon substrate.

Properties Analysis of Disk Spring with Effects of Asymmetric Variable Friction

2021 ◽  
Author(s):  
Renzhen Chen ◽  
Xiaopeng Li ◽  
Jinchi Xu ◽  
Zemin Yang ◽  
Hexu Yang
Keyword(s):  
Friction Coefficient ◽  
Vibration Isolation ◽  
Normal Load ◽  
Static Friction ◽  
Primary Objective ◽  
Friction Model ◽  
Computational Accuracy ◽  
Static Friction Coefficient ◽  
Disk Spring ◽  
Variable Friction

The primary objective of this fundamental research is to investigate the mechanical properties of the disk spring when the friction at the contact edges is asymmetric and varies with the load. The contact mechanics study shows that the static friction and static friction coefficient on fractal surfaces change depending on the normal load. In this paper, a fractal contact model based on the W-M function is used to explore the connection between the static friction and the normal load. Subsequently, taking into account the asymmetry of the contact surface at the edge, the variable static friction coefficient is brought into the existing model to obtain an improved static model of the disk spring. Different fractal dimensions, frictional states and free heights are considered under quasi-static loading condition, the relative errors between this paper and the method using Coulomb friction are also calculated, and experimental validation was performed. The static stiffness and force hysteresis of the disk spring for different forms of asymmetric variable friction are discussed. It is shown that using the variable friction model can improve the computational accuracy of the disk spring model under small loads and help to improve the design and control accuracy of preload and vibration isolation equipment using the disk spring as a component.

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