The Elastic—Plastic Contact of Rough Surfaces and its Relevance in the Study of Wear

1988 ◽  
Vol 202 (4) ◽  
pp. 269-274 ◽  
Author(s):  
J Halling ◽  
R D Arnell ◽  
K A Nuri
Keyword(s):  
Theoretical Model ◽  
Probability Distribution ◽  
Experimental Evidence ◽  
Rough Surfaces ◽  
Plasticity Index ◽  
Elastic Behaviour ◽  
Asperity Height ◽  
Real Contact ◽  
Nominal Pressure ◽  
Unique Relationship

In a recent paper it was shown that the limit of elastic behaviour of rough surfaces could be defined by a unique relationship between the plasticity index and the nominal pressure. Specific experimental evidence suggested that the best theoretical model was one when the asperity height probability distribution was assumed Gaussian with a truncation of 3 σ. This paper extends this argument by showing that for a given ratio of plastic-elastic area of real contact, similar unique relations exist between the plasticity index and nominal pressure. It is assumed that the maximum non-dimensional elastic deformation is given by the inverse of the square of the plasticity index, and this is supported by experimental results. It is also shown that the model proposed is in error at higher pressures, due to the interaction of the deformations of adjacent asperities.

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 Theoretical description of large deformations in criss-cross composites (with application to Tensylon®)

2020 ◽  
Vol 23 (2) ◽  
pp. 269-281
Author(s):  
Pavel S. Mostovykh
Keyword(s):  
Theoretical Model ◽  
Anisotropic Material ◽  
Large Deformations ◽  
Theoretical Description ◽  
Elastic Behaviour ◽  
Large Strains ◽  
Experi Mental Data ◽  
Deforma Tion

A theoretical model of an anisotropic material, Tensylon®, under large strains is proposed. This model is capable to describe the material’s response in in-plane tension at different angles to the fibrils. At 0° and at 90°, i.e., along the fibrils in either “criss” or “cross” plies, it quantitatively predicts the experimentally observed elastic behaviour until failure. At 45° to the fibrils, it quantitatively describes the experi- mental data in the elastic and plastic domains. The description remains accurate up to strains of 35%, that corresponds to 30÷40% of deforma- tion gradient components. The infinitesimal strains model would give at least 25% of error under such circumstances.

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.

Theoretical model for enhanced photochemistry on rough surfaces

1981 ◽  
Vol 75 (5) ◽  
pp. 2205-2214 ◽  
Author(s):  
Abraham Nitzan ◽  
L. E. Brus
Keyword(s):  
Theoretical Model ◽  
Rough Surfaces

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.

A Method for Determining the Non-Gaussian Probability Density Functions of Asperity Heights for Two Contact Surface Conditions

2007 ◽  
Author(s):  
Jeng Luen Liou ◽  
Jen Fin Lin
Keyword(s):  
Probability Density ◽  
Contact Surface ◽  
Elastic Recovery ◽  
Normal Load ◽  
Plasticity Index ◽  
Asperity Height ◽  
Engineered Surfaces ◽  
Change In The Mean ◽  
The Mean ◽  
Non Gaussian

Most statistical contact analyses assume that asperity height distributions (g(z*)) follow a Gaussian distribution. However, engineered surfaces are frequently the non-Gaussian with a character dependent upon the material and surface state being evaluated. When two rough surfaces experience contact deformations, the original topography of the surfaces varies with different loads. Two kinds of topographies are considered in the present study. The first kind of topography is obtained during the contact of two surfaces under a normal load. The second kind of topography is obtained from a rough contact surface after the end of the elastic recovery. The g(z*) profile is quite sharp and has a large value at its peak if it is obtained from the surface contacts under a normal load. The g(z*) profile defined for a contact surface after the elastic recovery is quite close to the g(z*) profile before contact deformations occur if the plasticity index is a small value. However, the g(z*) profile for the contact surface after the end of elastic recovery is closer to the g(z*) profile shown in the contacts under a normal load if a large plasticity index is assumed. Skewness (Sk) and kurtosis (Kt), which are the parameters in the probability density function, are affected by the change in the mean separation of two contact surfaces, or the initial skewness (the initial kurtosis is fixed in this study), or the plasticity index of the rough surface are also discussed on the basis of the topography models mentioned above.

Studies of Low-loading Micro-slip Contacts on Rough Surfaces with GW Model

2017 ◽  
Vol 09 (04) ◽  
pp. 1750049 ◽  
Author(s):  
Pin Lu ◽  
Lulu Yang ◽  
Gangfeng Wang
Keyword(s):  
Rough Surfaces ◽  
Extended Model ◽  
Interfacial Slip ◽  
Slip Model ◽  
Roughness Parameters ◽  
Asperity Height ◽  
Contact Conditions ◽  
Lateral Contact ◽  
Low Load ◽  
General Relations

Lateral loading and interfacial slip of multi-asperity (i.e., rough) elastic contacts are studied for micro-slip contact conditions. The Mindlin micro-slip model for smooth surfaces is generalized to rough surface contacts using the Greenwood–Williamson (GW) approach, and the general relations of lateral contact force and related stiffness are obtained. The method extends previous approaches by incorporating micro-slip, allowing application to rough surfaces and providing simple expressions for experimental analysis by use of the Greenwood–Williams roughness parameters. As applications, the numerical results of micro-slip contacts on rough surfaces for Gaussian and exponential asperity height distributions, respectively, are obtained based on the general relations of the extended model, and are compared and discussed for low load cases.

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