Pressures Distributions and Depth Stresses Developed in Concentrated Contacts Between Elements With Non-Gaussian Rough Surfaces

2012 ◽  
Author(s):  
Ana C. Urzică ◽  
Mihaela Rodica D. Bălan ◽  
Spiridon S. Creţu
Keyword(s):  
Pressure Distribution ◽  
Autocorrelation Function ◽  
Contact Area ◽  
Rough Surfaces ◽  
Spectral Characteristics ◽  
Equivalent Stress ◽  
Real Contact Area ◽  
Main Step ◽  
Spatial Characteristics ◽  
Non Gaussian

The main step in a contact analysis between rough surfaces is the evaluation of the pressure distribution developed on the real contact area. The normal pressure distribution can be used further to predict subsurface stress, interfacial friction and surface wear. Only few real rough surfaces are Gaussian, most of that produced by manufacturing processes are non-Gaussian having an arbitrarily orientation. The definition of the roughness will include, in addition to the spatial characteristics, information about spectral characteristics of the surface, described with the use of autocorrelation function ACF. Conjugate Gradient Method in conjunction with Discrete Convolution Fast Fourier Transform was refined and applied to solve the constrained system of equations that governs the pressure distribution between rough surfaces subjected to contact loading in elastic dry conditions. The paper reveals the role played by the spatial characteristics (standard deviation σ, skewness Sk, and kurtosis K) as well as by autocorrelation function on both the non-Hertzian pressure distribution on contact area and depth distribution of von Mises equivalent stress.

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.

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.

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 A semi-analytical approach to the elastic loading behaviour of rough surfaces

Friction ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 970-981
Author(s):  
Xiaogang Zhang ◽  
Yali Zhang ◽  
Zhongmin Jin
Keyword(s):  
Contact Area ◽  
Rough Surfaces ◽  
Real Contact Area ◽  
Exponential Relationship ◽  
Load Range ◽  
Contact Behaviour ◽  
Elastic Loading ◽  
Moderate Load ◽  
Convergence Problems ◽  
Linear Decay

AbstractThe elastic loading behaviour of rough surfaces is derived based on the physical understanding of the contact phenomena, where the pressure distribution is analytically obtained without any negative values or convergence problems, thus the evolution of the contact behaviour is obtained in a semi-analytical manner. Numerical results obtained by the proposed approach facilitate the understanding of the contact behaviour in the following aspects: 1) the ratio of contact area to load decreases with an increase in real contact area; 2) normal approach-load relationship is approximated by an exponential decay under relatively small loads and a linear decay under relatively large loads; and 3) average gap shows an exponential relationship with load only in moderate load range.

A Microcontact Model Developed for Asperity Heights with a Variable Profile Fractal Dimension, A Surface Fractal Dimension, Topothesy, and Non-Gaussian Distribution

2009 ◽  
Vol 25 (1) ◽  
pp. 103-115
Author(s):  
J. L. Liou ◽  
J. F. Lin
Keyword(s):  
Fractal Dimension ◽  
Contact Area ◽  
Distribution Functions ◽  
Real Contact Area ◽  
Contact Deformation ◽  
Surface Fractal Dimension ◽  
Surface Fractal ◽  
Deformation Regime ◽  
The Mean ◽  
Non Gaussian

AbstractThe cross sections formed by the contact asperities of two rough surfaces at an interference are islandshaped, rather than having the commonly assumed circular contour. These island-shaped contact surface contours show fractal behavior with a profile fractal dimension Ds. The surface fractal dimension for the asperity heights is defined as D and the topothesy is defined as G. In the study of Mandelbrot, the relationship between D and Ds was given as D = Ds + 1 if these two fractal dimensions are obtained before contact deformation. In the present study, D, G, and Ds are considered to be varying with the mean separation (or the interference at the rough surface) between two contact surfaces. The D-Ds relationships for the contacts at the elastic, elastoplastic, and fully plastic deformations are derived and the inceptions of the elastoplastic deformation regime and the fully plastic deformation regime are redefined using the equality of two expressions established in two different ways for the number of contact spots (N). The contact parameters, including the total contact force and the real contact area, were evaluated when the size distribution functions (n) for the three deformation regimes were available. The results indicate that both the D and Ds parameters in these deformation regimes increased with increasing the mean separation (d*). The initial plasticity index before contact deformation (ψ)0 is also a factor of importance to the predictions of the contact load (F*t) and contact area (At*) between the model of variable D and G, non-Gaussian asperity heights and circular contact area and the present model of variable D and G, non-Gaussian asperity heights and fractal contact area.

Influence of the in-plan distribution of asperities on the normal contact of periodically rough surfaces

2016 ◽  
Vol 230 (9) ◽  
pp. 1382-1391
Author(s):  
K Houanoh ◽  
H-P Yin ◽  
J Cesbron ◽  
Q-C He
Keyword(s):  
Numerical Simulations ◽  
Half Space ◽  
Contact Area ◽  
Rough Surfaces ◽  
Elastic Half Space ◽  
Real Contact Area ◽  
Normal Contact ◽  
Real Contact ◽  
Full Contact ◽  
Rigid Surfaces

The present work aims to analyze the influence of the in-plan distribution of asperities on the contact between periodically rough surfaces. Square pattern and hexagonal pattern rigid surfaces are considered. Their contact with an elastic half-space is analyzed by numerical simulations. Three surfaces are generated with identical asperities periodically distributed in a plan according to different patterns. It follows from numerical results that when the load and the real contact area are small, the asperities act almost independently. However, the interaction between close asperities increases with the load becomes intensified and has a significant effect on the contact area when the situation is close to full contact.

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.

Prediction of Contact Area and Frictional Behaviour of Rubber on Rigid Rough Surfaces

2014 ◽  
Author(s):  
Hagen Lind ◽  
Matthias Wangenheim
Keyword(s):  
Contact Area ◽  
Surface Texture ◽  
Rough Surfaces ◽  
Scale Model ◽  
Real Contact Area ◽  
Contact Friction ◽  
Sliding Velocity ◽  
Normal Contact ◽  
Multi Scale ◽  
Frictional Behaviour

In the tire-road contact friction depends on several influencing variables (e.g. surface texture, real contact area, sliding velocity, normal contact pressure, temperature, tread block geometry, compound and on the existence of a lubrication film). A multi-scale model for prediction of contact area and frictional behaviour of rubber on rigid rough surfaces at different length scales is presented. Within this publication the multi-scale approach is checked regarding convergence. By means of the model influencing parameters like sliding velocity, compound and surface texture on friction and contact area will be investigated.

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