scholarly journals Measurement of Real Contact Area for Rough Metal Surfaces and the Distinction of Contribution From Elasticity and Plasticity

2020 ◽  
Vol 143 (7) ◽  
Author(s):  
Lei-Tao Li ◽  
Xuan-Ming Liang ◽  
Yu-Zhe Xing ◽  
Duo Yan ◽  
Gang-Feng Wang
Keyword(s):  
Contact Area ◽  
Rough Surfaces ◽  
Normal Load ◽  
Real Contact Area ◽  
The Real ◽  
Physical Mechanisms ◽  
Frustrated Total Internal Reflection ◽  
Real Contact ◽  
New Apparatus ◽  
Elastic And Plastic Deformation

Abstract The measurement of the real contact area between rough surfaces is one of the most challenging problems in contact mechanics and is of importance to understand some physical mechanisms in tribology. Based on the frustrated total internal reflection, a new apparatus is designed to measure the real contact area. For metallic samples with various surface topographies, the relation between normal load and the real contact area is measured. The unloading process is first considered to distinguish the contribution of elasticity and plasticity in contact with rough surfaces. It is found that both elasticity and plasticity are involved throughout the continuous loading process, different from some present understanding and assumptions that they play at different loading stages. A quantitative parameter is proposed to indicate the contribution of plasticity. The present work not only provides an experimental method to measure the real contact area but figures out how elastic and plastic deformation works in contact with rough surfaces.

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.

Elastic-Plastic Contact Behavior Considering Asperity Interactions for Surfaces With Various Height Distributions

2005 ◽  
Vol 128 (2) ◽  
pp. 245-251 ◽  
Author(s):  
Yeau-Ren Jeng ◽  
Shin-Rung Peng
Keyword(s):  
Contact Area ◽  
Rough Surfaces ◽  
Local Deformation ◽  
Real Contact Area ◽  
Recent Experimental Data ◽  
The Real ◽  
Surface Separation ◽  
Real Contact ◽  
The Mean ◽  
Non Gaussian

This study investigates the effects of asperity interactions on the mean surface separation and the real contact area for rough surfaces with non-Gaussian height distributions. The effects of the asperity interactions on the local deformation behavior of a given microcontact are modeled using the Saint Venant principle and Love’s formula. The non-Gaussian rough surfaces are described by the Johnson translatory system. The results indicate that asperity interactions can significantly affect the mean separation of surfaces with non-Gaussian height distributions. The findings also reveal that the contact load and the real contact area of surfaces with non-Gaussian height distributions are significantly different from those of surfaces with Gaussian height distributions. This study uncovers that skewed surfaces tend to deform more elastically, which provides underlying physics for the long-time conventional wisdom and recent experimental data [Y. R. Jeng, 1996, Tribol. Trans., 39, 354–361;Y. R. Jeng, Z. W. Lin, and S. H. Shyo, 2004, ASME J. Tribol., 126, 620–625] that running-in surfaces have better wear resistance.

An incremental equivalent circular contact model for rough surfaces

2021 ◽  
pp. 1-16
Author(s):  
Gangfeng Wang ◽  
Xuan-Ming Liang ◽  
Yan Duo
Keyword(s):  
Contact Area ◽  
Rough Surfaces ◽  
Normal Load ◽  
Real Contact Area ◽  
Contact Radius ◽  
Surface Separation ◽  
Real Contact ◽  
Proposed Model ◽  
Geometrical Information ◽  
Circular Contact

Abstract The accurate calculation of real contact area between rough surfaces is a key issue in tribology. In this paper, based on the geometrical information of total contact area and the number of contact patches with respect to surface separation, a new method is proposed to determine the relation between real contact area and normal load. The contact of rough surfaces is treated as an accumulation of equivalent circular contacts with varying average contact radius. For a realistic range of separation, the proposed model predicts a linear relation between real contact area and load, and coincides well with direct finite element calculations. Moreover, this model is general and not confined to isotropic Gaussian surfaces.

An Efficient Multiscale Strategy to Predict the Evolution of the Real Contact Area between Rough Surfaces

2021 ◽  
pp. 107255
Author(s):  
R. Pinto Carvalho ◽  
A.M. Couto Carneiro ◽  
F.M. Andrade Pires ◽  
T. Doca
Keyword(s):  
Contact Area ◽  
Rough Surfaces ◽  
Real Contact Area ◽  
The Real ◽  
Real Contact

Effect of normal load on the frictional and wear behaviour of carbon fiber in tow-on-tool contact during three-dimensional weaving process

2020 ◽  
pp. 152808372094461
Author(s):  
Ning Wu ◽  
Ximing Xie ◽  
Jie Yang ◽  
Yajie Feng ◽  
Yanan Jiao ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Contact Area ◽  
Normal Load ◽  
Three Dimensional ◽  
Hertzian Contact ◽  
Wear Behaviour ◽  
Real Contact Area ◽  
The Real ◽  
Real Contact ◽  
Fracture Damage

The effect of normal load on the frictional and wear behaviour of carbon fiber is investigated by simulating the tow-on-tool friction relevant to the beating-up motion of three-dimensional (3 D) weaving process. The true number of contact filaments over a range of normal loads is calculated by characterizing the cross-section parameters of carbon tow. The real contact area is calculated on the basis of the filaments amount by Hertzian contact model. The friction force values obtained from multiplying the real contact area with shear strength are closely with the measured results. The coefficient of friction increases with the increase of normal loads. When the normal load is 250, 400 and 600 mN, the tensile loss rate of the carbon tow after friction test is 6.3%, 23.2% and 42.4% respectively. The filaments reveal multiple fracture damage patterns which are caused by stretching, shearing and compression during the weaving process.

Contact Behavior of Surfaces Containing Elliptical Asperities With Gaussian and Non-Gaussian Height Distributions

2007 ◽  
Vol 129 (4) ◽  
pp. 743-753 ◽  
Author(s):  
Yeau-Ren Jeng ◽  
Shin-Rung Peng
Keyword(s):  
Contact Area ◽  
Rough Surfaces ◽  
Single Mode ◽  
Real Contact Area ◽  
Height Distribution ◽  
Contact Mode ◽  
Contact Behavior ◽  
The Real ◽  
Real Contact ◽  
Non Gaussian

This study investigates the effects of asperity interactions on the mean surface separation and real contact area of rough surfaces containing elliptical asperities with Gaussian and non-Gaussian height distributions. The elastic-plastic contact behavior of surfaces with elliptical asperities with both single-mode and bimodal height distributions are studied. The results indicate that the effects of asperity interactions become more pronounced as the effective radius ratio of the asperities increases. The findings also reveal that the real contact load, the real contact area, and the surface contact mode observed for elliptical asperities are significantly different from those noted for spherical asperities. Furthermore, it is found that the form of the non-Gaussian height distribution has a significant effect on the contact mode of rough surfaces. Specifically, the contact mode of surfaces with a negatively skewed height distribution is found to be more elastic than that of surfaces with a Gaussian height distribution.

Analysis of Contact Area Between an Elasto-Plastic Rough Body and a Flat Body Under Different Working Mode

2014 ◽  
Author(s):  
Jianmeng Huang ◽  
Chenghui Gao ◽  
Youxi Lin ◽  
Xiezhao Lin
Keyword(s):  
Contact Area ◽  
Sliding Friction ◽  
Normal Load ◽  
Equivalent Plastic Strain ◽  
Real Contact Area ◽  
Three Dimensional Model ◽  
The Real ◽  
Mechanical Coupling ◽  
Real Contact ◽  
Rough Body

A thermo-mechanical coupling contact model between a fractal rough body and a flat body is established. In the model, the heat flux coupling between the sliding surfaces and the effect of elasto-plastic deformation of the rough body are considered. To obtain the transient microcontact process between the rough body and the flat body during rotating sliding friction, the thermo-mechanical problem under this three-dimensional model is solved by the nonlinear finite element multi-physical methods. The comparisons of the real contact area are analyzed under two different working modes, including loading processes with and without frictional rotating. During the loading and rotating process, the shear stress and the total frictional force on the frictional rough interface, and the equivalent plastic strain of the contact asperity are larger. All these including the thermal expansion make the real contact area increase with the applied normal load much faster under the working mode of loading and rotating than it does under the only loading mode.

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