scholarly journals Mechanics Analysis of Rough Surface Based on Shoulder-Shoulder Contact

2021 ◽  
Vol 11 (17) ◽  
pp. 8048
Author(s):  
Qiuping Yu ◽  
Jianjun Sun ◽  
Zhengbo Ji
Keyword(s):  
Rough Surface ◽  
Contact Area ◽  
Rough Surfaces ◽  
Geometric Model ◽  
Mechanical Analysis ◽  
Real Contact Area ◽  
Mechanics Model ◽  
Porosity Reduction ◽  
Fractal Roughness ◽  
Fractal Characteristics

Proper methods and models for mechanical analysis of rough surface can improve the theory of surface contact. When the topography parameters of two rough surfaces are similar, the contact should be considered shoulder-shoulder rather than top-top. Based on shoulder-shoulder contact and fractal characteristics, the geometric model for asperity and contact mechanics model for rough surfaces are established, and the deformation of asperity, the real contact area and contact load of sealing surface are discussed. The effects of contact pressure p and topography parameters (fractal dimension D and fractal roughness G) on the variation of porosity and contact area ratio Ar/A0 are achieved. Results show that with the increase of p, larger D and smaller G corresponds to larger initial porosity but faster and larger decrease of porosity; with the increment of D, porosity increases first and then decreases, and smaller G corresponds to larger porosity reduction; as G becomes bigger, porosity increases, and larger D corresponds to larger porosity difference and change. With the addition of p, Ar/A0 increases, and the variation of Ar/A0 is closer to linearity and less at smaller D and larger G; with the increase of D, Ar/A0 increases gradually, and the growth rate is bigger at smaller G and bigger p; as G becomes bigger, Ar/A0 declines, and it declines more gently at smaller D and p. The influence of D on Ar/A0 is greater than that of G. The results can provide the theoretical basis for the design of sealing surfaces and the research of sealing or lubrication technologies of rough surfaces.

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.

A Contact Mechanics Model for Rough Surfaces Based on a New Fractal Characterization Method

2018 ◽  
Vol 10 (06) ◽  
pp. 1850069 ◽  
Author(s):  
Jianjun Sun ◽  
Zhengbo Ji ◽  
Yuyan Zhang ◽  
Qiuping Yu ◽  
Chenbo Ma
Keyword(s):  
Contact Mechanics ◽  
Rough Surface ◽  
Contact Pressure ◽  
Contact Area ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Measurement Scale ◽  
Real Contact Area ◽  
Sample Length ◽  
Normal Contact

There are mainly two kinds of contact mechanics models for rough surfaces. One is based on the statistical characteristic parameters and depends on the measurement scale of rough surface topography. The other is based on the fractal parameters, which is independent of the measurement scale. However, most of the contact models for rough surfaces based on fractal theory use the size that is corresponding to the contact area of an asperity or the sample length as the base diameter of an asperity to describe the initial profile of asperities. As a result, the obtained deformation mechanism of asperities is not correct. To solve this problem, a new fractal characterization method for rough surfaces based on the fractal dimension [Formula: see text], fractal roughness [Formula: see text] and the highest asperity height is proposed, and then a fractal contact model independent of the measurement scale is established. The contact mechanism of asperities and variation trends of the real contact area and contact stiffness are discussed. When the contact pressure of the rough surface is less than its yield strength, its normal contact stiffness can be expressed as the first derivative of the contact pressure versus the normal compression, regardless of the deformation forms of asperities.

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.

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.

Deterministic Contact Model of a Rough Surface Against a Flat-Layered Surface

2004 ◽  
Author(s):  
H. R. Pasaribu ◽  
D. J. Schipper
Keyword(s):  
Mechanical Properties ◽  
Rough Surface ◽  
Contact Area ◽  
Indentation Depth ◽  
Normal Load ◽  
Contact Model ◽  
Real Contact Area ◽  
Single Asperity ◽  
Real Contact ◽  
Effective Mechanical Properties

The effective mechanical properties of a layered surface vary as a function of indentation depth and the values of these properties range between the value of the layer itself and of the substrate. In this paper, a layered surface is modelled like a solid that has effective mechanical properties as a function of indentation depth by assuming that the layer is perfectly bounded to the substrate. The normal load as a function of indentation depth of sphere pressed against a flat layered surface is calculated using this model and is in agreement with the experimental results published by El-Sherbiney (1975), El-Shafei et al. (1983), Tang & Arnell (1999) and Michler & Blank (2001). A deterministic contact model of a rough surface against a flat layered surface is developed by representing a rough surface as an array of spherically shaped asperities with different radii and heights (not necessarily Gaussian distributed). Once the data of radius and height of every single asperity is obtained, one can calculate the number of asperities in contact, the real contact area and the load carried by the asperities as a function of the separation.

Contact Mechanics Analysis of Two Rough Surfaces in Contact

2010 ◽  
Vol 154-155 ◽  
pp. 531-534 ◽  
Author(s):  
Zhi Qian Xu ◽  
Xiang Zhen Yan ◽  
Xiu Juan Yang
Keyword(s):  
Quantitative Analysis ◽  
Contact Pressure ◽  
Contact Area ◽  
Rough Surfaces ◽  
Mechanical Analysis ◽  
Average Pressure ◽  
Calculation Formula ◽  
Analysis Method ◽  
Mechanics Analysis ◽  
Quantitative Analysis Method

In this paper, the calculation formulas of the asperity’s deformation related with the surface contact pressure are deduced by using the simplified contact model. Firstly, we assume that the rough surface is composed of a set of cones as asperities, and the cones are arranged in different ways along two directions. Secondly, according to the mechanical analysis of a rigid conical punch on a half-space, the theoretical relationship between the average pressure of the micro contact area and the property parameters of a conical punch is obtained. Meanwhile, the calculation formula of the average pressure is given under the reasonable assumptions, which is related with the asperity’s deformation and the contact pressure. Finally, combining two theoretical relationships above, the quantitative analysis method for micro asperity’s deformation of two rough surfaces in contact is provided by using the average pressure as a connection bridge.

Plane Contact and Partial Slip Behaviors of Elastic Layers With Randomly Rough Surfaces

2015 ◽  
Vol 82 (9) ◽  
Author(s):  
Fan Jin ◽  
Qiang Wan ◽  
Xu Guo
Keyword(s):  
Rough Surface ◽  
Contact Area ◽  
Elastic Layer ◽  
Partial Slip ◽  
Real Contact Area ◽  
Rigid Base ◽  
Slip Model ◽  
Normal Contact ◽  
Real Contact ◽  
Plane Contact

A plane contact and partial slip model of an elastic layer with randomly rough surface were established by combining the Greenwood–Williamson (GW) rough contact model and the Cattaneo–Mindlin partial slip model. The rough surface of the elastic layer bonded to a rigid base is modeled as an ensemble of noninteracting asperities with identical radius of curvature and Gaussian-distributed heights. By employing the Hertzian solution and the Cattaneo–Mindlin solution to each individual asperity of the rough surface, we derive the total normal force, the real contact area, and the total tangential force for the rough surface, respectively, and then examine the normal contact and partial slip behaviors of the layer. An effective Coulomb coefficient is defined to account for interfacial friction properties. Furthermore, a typical stick–slip transition for the rough surface was also captured by distinguishing the stick and slip contacting asperities according to their respective indentation depths. Our analysis results show that an increasing layer thickness may result in a larger real contact area, a lower mean contact pressure, and a higher effective Coulomb coefficient.

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