Adhesion Model for Metallic Rough Surfaces

1988 ◽  
Vol 110 (1) ◽  
pp. 50-56 ◽  
Author(s):  
W. R. Chang ◽  
I. Etsion ◽  
D. B. Bogy
Keyword(s):  
Surface Roughness ◽  
Surface Energy ◽  
Adhesion Force ◽  
Rough Surfaces ◽  
Contact Model ◽  
External Loading ◽  
Elastic Plastic ◽  
Adhesion Model ◽  
Very High

An improved DMT adhesion model in conjunction with an elastic-plastic contact model is used to study adhesion of contacting metallic rough surfaces. The effects of surface roughness and surface energy of adhesion on the pull-off force and on the significance of the adhesion force are investigated. It is shown that for clean surfaces the adhesion is quite large even for relatively rough surfaces. Adhesion is negligible only for contaminated rough surfaces or at very high external loading.

Adhesion of Contacting Rough Surfaces in the Presence of Sub-Boundary Lubrication

1990 ◽  
Vol 112 (1) ◽  
pp. 98-104 ◽  
Author(s):  
H. M. Stanley ◽  
I. Etsion ◽  
D. B. Bogy
Keyword(s):  
Film Thickness ◽  
Boundary Lubrication ◽  
Critical Thickness ◽  
Rough Surfaces ◽  
Thin Layers ◽  
Solid Surfaces ◽  
High Affinity ◽  
Wide Range ◽  
Adhesion Model ◽  
Very High

An improved DMT adhesion model is used in conjunction with an elastoplastic contact model to analyze the adhesion of contacting rough solid surfaces covered with extremely thin layers of a lubricant having a very high affinity for the surfaces. This we call sub-boundary lubrication. The paper investigates the effects of the solid surface topography and the film thickness of the lubricant on the adhesion and pull-off forces. A roughness-dependent critical thickness phenomenon is predicted: very rough surfaces may exhibit low adhesion for a wide range of lubricant thicknesses, while for smooth surfaces adhesion may increase dramatically even for a film thickness t below the standard deviation of surface heights σ. The increased adhesion could cause the surfaces to stick together to the extent that sensitive tribological systems may be damaged.

Contact Analysis of Multilayered Elastic/Plastic Solids With Rough Surfaces for Decreasing Friction and Wear

2005 ◽  
Author(s):  
Shaobiao Cai ◽  
Bharat Bhushan
Keyword(s):  
Surface Roughness ◽  
Contact Area ◽  
Yield Criterion ◽  
Rough Surfaces ◽  
Three Dimensional ◽  
Surface Displacement ◽  
Maximum Displacement ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Von Mises

A numerical three-dimensional contact model is presented to investigate the contact behavior of multilayered elastic-perfectly plastic solids with rough surfaces. The surface displacement and contact pressure distributions are obtained based on the variational principle with fast Fourier transform (FFT)-based scheme. Von Mises yield criterion is used to determine the onset of yield. The effective hardness is modeled and plays role when the local displacement meet the maximum displacement criterion. Simulations are performed to obtain the contact pressures, fractional total contact area, fractional plastic contact area, and surface/subsurface stresses. These contact statistics are analyzed to study the effects of the layer-to-substrate ratios of stiffness and hardness, surface roughness, and layers thickness of rough, two-layered elastic/plastic solids. The results yield insight into the effects of stiffness and hardness of layers and substrates, surface roughness, and applied load on the contact performance. The layer parameters leading to low friction, stiction, and wear are investigated and identified.

The Investigation of Energy Loss in Conformal Contact Mechanics of Carpal-Radial Components in Wrist Arthroplasty

2014 ◽  
Author(s):  
Mohammad Hodaei ◽  
Kambiz Farhang
Keyword(s):  
Surface Roughness ◽  
Energy Loss ◽  
Contact Mechanics ◽  
Contact Force ◽  
Rough Surfaces ◽  
Approximate Equation ◽  
Integral Function ◽  
Contact Model ◽  
Metal Debris ◽  
Surface Separation

The contact mechanics of Wrist prosthetic implant is considered in which the surface roughness of the implant is included. Total wrist replacements are developed to perform wrist function as near normal as possible. The main goal of wrist replacement surgery is to relieve patients from painful arthritis and to maintain function in the wrist and hand. The gradual wearing away of the cartilage covering on bones can lead to the most common form of arthritis, usually osteoarthritis. Wear is a very important issue in wrist implant. Metal debris caused by excessive wear in wrist implant can lead to toxicity and patient discomfort. Since implant wear can be the result of contact between surfaces of Carpal and Radial components, so the investigation of the effect of roughness between wrist components and establishing a model for interaction of surface roughness is very important. There are several different designs of wrist implant. Most of them have two components that are made of metal. A high quality plastic called polyethylene is used as a space between the two components. The purpose of this paper is to investigate the effect of roughness between interaction of these metal and polyethylene in wrist implants. This paper develops a contact model to treat the interaction of Carpal - Radial Components. The contact model describes the interaction of implant rough surfaces including both elastic and plastic deformations. In the model, surfaces are investigated as macroscopically conforming semi-Cylinder containing micron-scale roughness. The derived equations relate contact force on the implant and the minimum mean surface separation of the rough surfaces. Based on the distribution of asperity heights, the force is expressed using statistical integral function of asperity heights over the possible region of interaction of the roughness of the implant surfaces. Closed-form approximate equation relating contact force and minimum separation is used to obtain energy loss per cycle in a load-unload sequence applied to the implant.

A statistical model of elastic-plastic contact between rough surfaces

2019 ◽  
Vol 43 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Guang Zhao ◽  
Sheng-xiang Li ◽  
Zhi-liang Xiong ◽  
Wen-dong Gao ◽  
Qing-kai Han
Keyword(s):  
Plastic Deformation ◽  
Interface Design ◽  
Present Model ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Contact Point ◽  
Contact Model ◽  
Elastic Plastic ◽  
Classical Models ◽  
Asperity Deformation

In a mechanical interface, the contact surface topography has an important influence on the contact stiffness. In the contact processes of asperities, elastic-plastic change can lead to discontinuity and lack of smoothness at a critical contact point. The result is a large difference between the elastic-plastic deformation and the actual asperity deformation. Based on Hertz contact theory, the heights of asperities on a rough surface obey a Gaussian distribution. To take into consideration the continuity of elastic-plastic asperity deformation, we divide the elastic-plastic deformation into three stages: pre-elastic-plastic, mid-elastic-plastic, and post-elastic-plastic deformation. This establishes an elastic-plastic contact model of asperity at a continuous critical point. The contact model of a single asperity fits well with the Kogut–Etsion model and the Zhao–Maietta–Chang model, and the variation trend is consistent. At a lower plastic index, the present model coincides with classical models of contact area and contact load. At a higher plastic index, the simulation results of the present model differ from the Greenwood–Williamson model and the Chang–Etsion–Bogy model but are similar to results from the Kogut–Etsion and Zhao–Maietta–Chang models. This study provides a more accurate microscopic contact model for rough surfaces and a theoretical framework for interface design and analysis.

Elastic-Plastic Contact Between Rough Surfaces: Proposal for a Wear or Running-In Model

2005 ◽  
Vol 128 (2) ◽  
pp. 236-244 ◽  
Author(s):  
D. Nélias ◽  
V. Boucly ◽  
M. Brunet
Keyword(s):  
Rough Surfaces ◽  
Companion Paper ◽  
Contact Model ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Mapping Algorithm ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Hardening Law ◽  
Von Mises

A semi-analytical thermo-elastic-plastic contact model has been recently developed and presented in a companion paper. The main advantage of this approach over the classical finite element method (FEM) is the treatment of transient problems with the use of fine meshing and the possibility of studying the effect of a surface defect on the surface deflection as well as on subsurface stress state. A return-mapping algorithm with an elastic predictor/plastic corrector scheme and a von Mises criterion is now used, which improves the plasticity loop. This improvement in the numerical algorithm increases the computing speed significantly and shows a much better convergence and accuracy. The contact model is validated through a comparison with the FEM results of Kogut and Etsion (2002, J. Appl. Mech., 69, pp. 657–662) which correspond to the axisymmetric contact between an elastic-perfectly plastic sphere and a rigid flat. A model for wear prediction based on the material removal during cyclic loading is then proposed. Results are presented, first, for initially smooth surfaces and, second, for rough surfaces. The effects of surface shear stress and hardening law are underlined.

Fractal modeling of elastic-plastic contact between three-dimensional rough surfaces

2018 ◽  
Vol 70 (2) ◽  
pp. 290-300 ◽  
Author(s):  
Rufei Yu ◽  
Wei Chen
Keyword(s):  
Rough Surfaces ◽  
Fractal Theory ◽  
Three Dimensional ◽  
Geometrical Model ◽  
Contact Model ◽  
Radial Clearance ◽  
Content Type ◽  
Elastic Plastic ◽  
Fractal Roughness ◽  
Conformal Contact

Purpose This paper aims to propose a semi-analytical model to investigate the elastic-plastic contact between fractal rough surfaces. Parametric studies have been performed to analyze the dependencies between the contact properties and the scale-independent fractal parameters. Design/methodology/approach A modified two-variable Weierstrass-Mandelbrot function has been used to build the geometrical model of rough surfaces. The computation program was developed using software MATLAB R2015a. The results have been qualitatively validated by the existing theoretical and experimental results in the literature. Findings In most cases, a nonlinear relation between the load and the displacement of the rigid plane is found. Only under the condition of larger loads, an approximate linear relation can be seen for great D and small G values. (D: fractal dimension and G: fractal roughness). Originality/value The contact model of the cylindrical joints (conformal contact) with radial clearance is constructed by using the fractal theory and the Kogut-Etsion elastic-plastic contact model, which includes purely elastic, elastic-plastic and fully plastic contacts. The present method can generate a more reliable calculation result as compared with the Hertz contact model and a higher calculation efficiency as compared with the finite element method for the conformal contact problem.

Resolving the Contradiction of Asperities Plastic to Elastic Mode Transition in Current Contact Models of Fractal Rough Surfaces

2005 ◽  
Author(s):  
Yahav Morag ◽  
Izhak Etsion
Keyword(s):  
Contact Mechanics ◽  
Contact Area ◽  
Rough Surfaces ◽  
Contact Model ◽  
Surprising Result ◽  
Critical Area ◽  
Contact Mode ◽  
Elastic Mode ◽  
Elastic Plastic ◽  
Current Contact

The elastic-plastic contact model of fractal rough surfaces offered by Majumdar and Bushan in 1991 (the MB model) is revisited. According to the MB model, the contact mode of a single fractal asperity transfers from plastic to elastic when the load is increased, and the asperity’s contact area grows and becomes larger than a critical area, which is scale independent. This surprising result of the MB model is in contrast with classical contact mechanics where an increase of contact area due to increased load, is associated with a transition from elastic to plastic contact. The present study describes a revised elastic-plastic contact model of a single fractal asperity showing that the critical area is scale dependent, contrary to the MB model prediction. The new model also shows that a fractal asperity behaves as would be expected from classical contact mechanics namely, as the load and contact area increase a transition from elastic to plastic contact takes place in this order.

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