The Contact of Two Nominally Flat Rough Surfaces

1970 ◽  
Vol 185 (1) ◽  
pp. 625-633 ◽  
Author(s):  
J. A. Greenwood ◽  
J. H. Tripp
Keyword(s):  
Surface Roughness ◽  
General Theory ◽  
Rough Surface ◽  
Rough Surfaces ◽  
Deformation Mode ◽  
Surface Model ◽  
Geometrical Properties ◽  
Rough Plane ◽  
Surface Contact ◽  
Compliance Curve

Most models of surface contact consider the surface roughness to be on one of the contacting surfaces only. The authors give a general theory of contact between two rough plane surfaces. They show that the important results of the previous models are unaffected: in particular, the load and the area of contact remain almost proportional, independently of the detailed mechanical and geometrical properties of the asperities. Further, a single-rough-surface model can always be found which will predict the same laws as a given two-rough-surface model, although the required model may be unrealistic. It does not seem possible to deduce the asperity shape or deformation mode from the load-compliance curve.

scholarly journals Fretting Wear Mechanical Analysis of Double Rough Surfaces Based on Energy Method

2021 ◽  
Author(s):  
Ling Li ◽  
Ganghua Li ◽  
JingJjing Wang ◽  
Xiaohui Shi ◽  
Anjiang Cai
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Rough Surface ◽  
Rough Surfaces ◽  
Research Work ◽  
Mechanical Analysis ◽  
Fretting Wear ◽  
Surface Model ◽  
Dissipation Model ◽  
And Performance

Abstract A fretting wear model of rough surface that conforms to the actual situation is established to accurately reveal the wear mechanism of the connection structure. In the ABAQUS software, the UMESHMOTION subroutine and the energy dissipation model are used to simulate the fretting wear of double rough surfaces. The new model, a single rough surface model, and a smooth model are compared to analyze the differences between them. In addition, the influence of surface roughness, material, and friction coefficient on the fretting wear of rough surfaces is systematically explored through finite element simulation. The results show that the reliability of the model has been verified through Hertz’s theory and experiments. The stress and wear of the contact surface are more realistically reflected by the double roughness model. Besides, with the increase of surface roughness and material rigidity and the decrease of friction coefficient, the wear of the double rough surface model becomes more severe. The research work provides a theoretical basis for the design and performance prediction of the connection structure.

A Comparative Study on Equivalent Modeling of Rough Surfaces Contact

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Xi Shi ◽  
Yunwu Zou
Keyword(s):  
Rough Surface ◽  
Rough Surfaces ◽  
Contact Analysis ◽  
Contact Forces ◽  
Sliding Contact ◽  
Contact Model ◽  
Surface Model ◽  
Normal Contact ◽  
Surface Contact ◽  
Rough Surface Contact

Greenwood and Tripp (GT model) have proposed that the contact analysis of two rough surfaces (two-rough-surface contact model) could be considered as an equivalent rough surface in contact with a rigid flat (single-rough-surface contact model). In this paper, by virtue of finite element method, the normal contact analysis was performed with two-rough-surface contact model and its equivalent single-rough-surface contact model, and it was verified that the resultant normal contact forces are in good agreement with each other for these two models, meanwhile the equivalent stress is a little bit lower for two-rough-surface model due to shoulder-to-shoulder contact. In contrast, the sliding contact analysis was also performed with these two models, respectively, and the results show a great disparity with each other in all contact parameters due to the strong plowing effects in two-rough-surface model. Therefore, this equivalence approach proposed by Greenwood and Tripp is only valid for normal contact of rough surfaces and not valid for sliding contact.

Lubrication of Rough Surfaces by a Boundary Film-Forming Viscosity Modifier Additive

2005 ◽  
Vol 127 (1) ◽  
pp. 223-229 ◽  
Author(s):  
R. P. Glovnea ◽  
A. V. Olver ◽  
H. A. Spikes
Keyword(s):  
Rough Surface ◽  
Rough Surfaces ◽  
Viscosity Index ◽  
Functionalized Polymers ◽  
Contact Conditions ◽  
Film Forming ◽  
Boundary Film ◽  
Surface Contact ◽  
Lubricated Contact ◽  
Rough Surface Contact

In previous work it was shown that some functionalized polymers used as viscosity index improvers are able to form thick boundary lubricating films. This behavior results from adsorption of the polymer on metal surfaces to form a layer of enhanced viscosity adjacent to the surface. In the current work the behavior of one such polymer in rough surface contact conditions is studied, using both model and real rough surfaces. It is found that the polymer is able to form a thick boundary film in rough surface contact, just as it does with smooth surfaces. It is also shown that the effect of this boundary film is to significantly reduce friction in rolling-sliding, rough surface, lubricated contact.

Testing the Validity of Greenwood and Tripp’s Sum Surface Assumption for Elastic-Plastic Contact

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Ashutosh Roy ◽  
Bhargava Sista ◽  
Kumar Vemaganti
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Correlation Length ◽  
Coefficient Of Friction ◽  
Rough Surfaces ◽  
Surface Model ◽  
Finite Element Models ◽  
Rigid Plane ◽  
Static Coefficient Of Friction ◽  
Static Coefficient

Abstract The complexity of modeling friction between rough surfaces has prompted many researchers to use Greenwood and Tripp’s sum surface assumption to simplify the analysis. This assumption approximates the contact between two rough surfaces as contact between their equivalent sum surface and a rigid plane. In this work, we develop detailed finite element models to test the sum surface assumption for surfaces with Gaussian and exponential autocorrelation functions. We consider surfaces with differing surface roughness and correlation length values. For each case, we conduct simulations of two rough surfaces interacting in compression followed by shear, and a corresponding equivalent surface model based on the sum surface assumption. Multiple realizations of each parameter combination are simulated to obtain a statistical picture of the responses. We find that (a) the sum surface assumption consistently under-predicts the static coefficient of friction and (b) the equivalent surface model is less accurate for surfaces with differing correlation length-to-surface roughness ratios.

An Efficient Multi-Scale Modeling Method that Reveals Coupled Effects Between Surface Roughness and Roll-Stack Deformation in Cold Sheet Rolling

2021 ◽  
pp. 1-53
Author(s):  
Feng Zhang ◽  
Arif S Malik
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Rough Surface ◽  
Material Behavior ◽  
Sheet Rolling ◽  
Elastic Plastic ◽  
Multi Scale ◽  
Macro Scale ◽  
Surface Contact ◽  
Rough Surface Contact

Abstract In thin-gauge cold rolling of metal sheet, the surface roughness of work-rolls is known to affect the rolled sheet surface morphology, the required rolling load, and the roll wear. While modeling of rough surfaces using statistical asperity theory has been widely applied to problems involving semi-infinite solids, the application of asperity distributions and their elastic-plastic behavior has not been considered in roll-stack models for cold sheet rolling. In this work, a simplified-mixed finite element method (SM-FEM) is combined with statistical elastic-plastic asperity theory to study contact interference and coupling effects between a rough work-roll surface and the roll-stack mechanics in cold sheet rolling. By mixing equivalent rough-surface contact foundations, Hertz foundations, and Timoshenko beam stiffness, an approach is created to efficiently model interactions between the micro-scale asperities and the macro-scale roll-stack deformation. Nonlinearities from elastic-plastic material behavior of the asperities and the sheet, as well as changing contact conditions along the roll length, are also accommodated. Performance of the multi-scale SM-FEM approach is made by comparison to a continuum finite element virtual material model. 3D studies for a 4-high mill reveal new multi-scale coupling behaviors, including non-uniform roughness transfer, and perturbations to the sheet thickness ‘crown’ and contact force profiles. The described multi-scale SM-FEM approach is general and applies to rough surface contact problems involving plates and shear-deformable beams having multiple contact interfaces and arbitrary surface profiles.

Effect of Surface Roughness on Fouling of Calcium Carbonate: An Experimental Investigation

2010 ◽  
Author(s):  
M. Izadi ◽  
D. K. Aidun ◽  
P. Marzocca ◽  
H. Lee
Keyword(s):  
Surface Roughness ◽  
Calcium Carbonate ◽  
Rough Surface ◽  
Smooth Surface ◽  
Rough Surfaces ◽  
Operating Conditions ◽  
Tubular Heat Exchanger ◽  
Analytical Microscopy ◽  
Deposit Layer ◽  
Effect Of Surface

The effect of surface roughness on the fouling behavior of calcium carbonate is experimentally investigated. The real operating conditions of a tubular heat exchanger are simulated by performing prolonged experiments with duration of 3 to 7 days. The solution used is a mixture of sodium bicarbonate and calcium chloride in de-ionized water with the concentration of 0.4 g/l of each. An on-line fouling evaluation system was developed such that the fouling resistance for a selected solution could be measured in real time. The experiments are repeated with the same procedure for 90/10 Cu/Ni tubes with different internal surface roughness. After the experiment the surface is analyzed by analytical microscopy to investigate the morphology of the deposit layer. Comparison of the experimental results of smooth and rough surfaces shows that a combination of aragonite and calcite polymorphs are formed on rough surface while only dendritic porous aragonite crystals are formed on smooth surface. Accordingly, the deposit layer formed on rough surface is denser and has a higher thermal resistance comparing to that formed on smooth surface. The fouling factor-time curves of smooth and rough surfaces obtained by the current experimental study agree with the results found by the analytical microscopy of the surface and show higher fouling resistances for rough surface. Experimental data is significantly important for the design, and formulating operating, and cleaning schedules of the equipment.

Surface Roughness Characterization of al Films by Spectroscopic Ellipsometry

1985 ◽  
Vol 54 ◽  
Author(s):  
J. R. Blanco ◽  
K. Vedam ◽  
P. J. McMarr ◽  
J. M. Bennett
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Spectroscopic Ellipsometry ◽  
Rough Surfaces ◽  
Scalar Theory ◽  
Nondestructive Technique ◽  
Aluminum Films ◽  
Random Rough Surfaces ◽  
Scalar Theory Of Diffraction

ABSTRACTWell characterized rough surfaces of aluminum films have been studied by the nondestructive technique of Spectroscopie Ellipsometry (SE). The roughness of the aluminum specimens had been characterized earlier by Total Integrated Scattering and Stylus Profilometry techniques to obtain numerical estimates of ras roughness and autocovariance lengths. The present SE measurements on these specimens were carried out at a number of angles of incidence in the range 30–80° and at a number of discrete wavelengths in the spectral range 300–650nm. The SE results were then analyzed by the scalar theory of diffraction from random rough surfaces by treating the surface as a simple random rough surface. The results of such analyses of the SE measurements are compared with the results of the earlier characterization techniques.

A Reconstruction and Contact Analysis Method of Three-Dimensional Rough Surface Based on Ellipsoidal Asperity

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Yuqin Wen ◽  
Jinyuan Tang ◽  
Wei Zhou ◽  
Lin Li
Keyword(s):  
Rough Surface ◽  
Rough Surfaces ◽  
Minimum Mean Square Error ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
Contact Analysis ◽  
Analysis Method ◽  
Surface Asperity ◽  
Surface Contact ◽  
Rough Surface Contact

Abstract The 3D rough surface modeling and contact analysis is a difficult problem in the study of rough surface contact. In this paper, a new method for reconstruction and contact analysis of asperities on 3D rough surfaces is proposed based on real rough surfaces. Watershed algorithm is used to segment and determine the area of asperities on the rough surface. According to the principle of minimum mean square error, ellipsoid fitting is carried out on asperities. Based on the elastic-plastic contact model of a single ellipsoidal asperity, a stable and efficient method for 3D rough surface contact analysis and calculation is proposed. Compared with existing calculating methods, the present method has the following characteristics: (1) the constructed surface asperity is closer to the real asperity in contact, and the calculation of asperity parameters has better stability under different sampling intervals and (2) the contact pressure, contact area, and other contact parameters of the 3D rough surface are calculated with high accuracy and efficiency, and the calculation convergence is desirable. The reconstruction and contact analysis method of the 3D rough surface asperity proposed in this paper provides a more accurate reconstruction and calculation method for the study of contact fatigue life and wear failure of rough surfaces.

A Micromechanical Dislocation Model of Rough Surface Contact Plasticity

2005 ◽  
Author(s):  
Y. F. Gao
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Micromechanical Model ◽  
Complex Surface ◽  
Dislocation Nucleation ◽  
Dislocation Model ◽  
Sensitive Material ◽  
Dislocation Plasticity ◽  
Surface Contact ◽  
Rough Surface Contact

Rough surface contact plasticity, especially at mesoscale and nanoscale, has been playing a central role in a broad spectrum of novel applications, e.g. nanostructure fabrication and reliability. The multiscale nature of surface roughness, the structure- and size-sensitive material deformation behavior, and the importance of surface forces and other physical interactions give rise to very complex surface phenomena at mesoscale and nanoscale. We present a micromechanical model to study rough surface contact plasticity, based on dislocation nucleation and multiplication. Surface roughness can be sources of dislocation nucleation; though roughness is confined to a thin layer, the resulted dislocation plasticity can extend to a far depth. Depending on interface adhesion, roughness features and slip planes, we get a variety of surface micro-plasticity behaviors that are radically different from classic plasticity behaviors.

Statistical Analysis of a Rough-Surface Model

1978 ◽  
Vol 20 (6) ◽  
pp. 315-318 ◽  
Author(s):  
N. B. Demkin ◽  
I.I. Berkovich ◽  
M. S. Kourova
Keyword(s):  
Statistical Analysis ◽  
Rough Surface ◽  
Surface Model ◽  
Surface Layers ◽  
Equal Radius ◽  
Surface Contact ◽  
Rough Surface Contact ◽  
Contact Parameters

The ‘stereometrical’ characteristics of the rough surface layers of engineering components, which are necessary for the calculation of rough-surface contact parameters, are often identified with the ‘planimetrical’ ones obtained from single profiles. In this paper, a relationship is obtained between these characteristics. Asperities are modelled by segments of spheres of equal radius and arbitrary height.

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