On a model for the prediction of asperity interactions of the coated friction pair

2019 ◽  
Vol 72 (3) ◽  
pp. 449-454 ◽  
Author(s):  
Chunxing Gu ◽  
Shuwen Wang
Keyword(s):  
Optimum Design ◽  
Numerical Experiments ◽  
Rough Surfaces ◽  
Contact Model ◽  
Real Contact Area ◽  
Plastic Behavior ◽  
Asperity Contact ◽  
Content Type ◽  
Contact Behavior ◽  
Elastic Plastic

Purpose Surface coatings have been introduced on the contact surfaces to protect the mechanical parts for a long time. However, in terms of the optimum design of coatings, some key coating parameters are still selected by trial and error. The optimum design of coatings can be conducted by numerical experiments. This paper aims to predict the contact behavior of the coated rough surfaces accurately. One improved asperity contact model for the coated rough surfaces considering the misalignment of asperities would be developed. Design/methodology/approach Incorporating the coated asperity contact model into the improved Greenwood Tripp-based statistical approach, the proposed model can predict the elastic-plastic behaviors of the interacting coated asperities. Findings According to numerical experiments, compared with the coated asperity contact model in which an equivalent rough surface against a plane is assumed, the improved asperity contact model for the coated contacts can account for the effect of permitting misalignment of two rough surfaces. The contacts having the thicker, stiffer and harder coatings result in higher asperity contact pressure and smaller real contact area fraction under the given Stribeck oil film ratio. Originality/value In this paper, one statistical coated asperity contact model for two rough surfaces was developed. The developed model can consider the elastic-plastic behavior of interacting coated asperities. The effects of the coating thickness and its mechanical properties on the contact behavior of the rough surfaces with coatings can be evaluated based on the developed model.

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.

The Contact Mechanics for Indentation of Single Asperity and Rough Surfaces

2022 ◽  
pp. 1-32
Author(s):  
Zhaoning Sun ◽  
Xiaohai Li
Keyword(s):  
Rough Surfaces ◽  
Real Contact Area ◽  
Rigid Sphere ◽  
Asperity Contact ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Single Asperity ◽  
Plastic Yield ◽  
Plastic Deformation Region ◽  
Contact Parameters

Abstract A Finite Element Analysis of a rigid sphere contact with a deformable elastic-plastic plat called indentation model is studied. The numerical results are applied on the rough surfaces contact of the GW model. A series of the relationships of the rough surfaces contact parameters are obtained. The contact parameters of the indentation model and the flattening model are compared in detail and the reasons for their differences are analyzed. In the case of single asperity contact, for ω/ωc > 1, the Indentation model reaches the initial plastic yield while the flattening model is ω/ωc = 1. In ω/ωc = 10, the plastic yield reaches the contact surface for the first time, and the corresponding point of ψ = 0.5 the flattening model is relatively earlier in . The contact parameters of rough surface in different plasticity indexes are compared again. On the point of ω/ωc = 6, the contact parameters of the flattening model and the indentation model coincide perfectly. For 0.5 < ψ < 4, the difference between the parameters curves become larger and larger. To the point of ψ = 4, when the distance difference reaches the maximum, it begins to decrease until the two curves are close to coincide again. The dimensionless elastic-plastic contact hardness is introduced. The relation between real contact area and the contact pressure of the indentation model can be acquired quickly. The results show that the geometric shape of deformable contact parts has an important effect on the contact parameters, especially for the extension of plastic deformation region within a specific range of plasticity index.

An Elliptic Elastic-Plastic Asperity Microcontact Model for Rough Surfaces

1998 ◽  
Vol 120 (1) ◽  
pp. 82-88 ◽  
Author(s):  
Jeng Haur Horng
Keyword(s):  
Present Model ◽  
Rough Surfaces ◽  
Plasticity Index ◽  
Contact Model ◽  
Real Contact Area ◽  
Elastic Plastic ◽  
Surface Topographies ◽  
Elliptic Contact ◽  
Contact Spots ◽  
Circular Contact

An elastic-plastic microcontact model, that takes into account the directional nature of surface roughness, is proposed for elliptic contact spots between anisotropic rough surfaces. In addition, the plasticity index was modified to suit more general geometric contact shapes. This contact model, which expands the usefulness of the CEB model, is also utilized to determine the effect of effective radius ratio (γ) on microcontact behavior and to compare the results of this model and other models under different surface topographies. The results show that the elliptic contact model and circular contact model deviate considerably in regard to the separation (h), total real contact area (At), plastic area (Ap) and plasticity index (Ψ). The present model can be simplified to become other stochastic models.

Thermal Elasto-Plastic Contact Model of Rough Surfaces

2005 ◽  
Author(s):  
Geng Liu ◽  
Tianxiang Liu ◽  
Qin Xie ◽  
Fanghui Shi
Keyword(s):  
Thermal Effects ◽  
Rough Surfaces ◽  
Frictional Heating ◽  
Contact Model ◽  
Stress Fields ◽  
Real Contact Area ◽  
Plastic Behavior ◽  
Contact Conditions ◽  
Real Contact ◽  
Frictional Coefficients

A thermal elasto-plastic contact model is developed in this paper to investigate the influences of steady-state frictional heating on the contact performance of surface asperities and subsurface stress fields. This model takes into account the asperity distortion caused by temperature variation in a tribological process, micro plastic flow of surface asperities, and the coupled thermo-elasto-plastic behavior of materials, with and without considering the strain-hardening property of the materials. The model is verified through the contact analysis between a rigid, isolated cylinder and a plane. Furthermore, the thermal effects on the contact pressure, real contact area, and average gap of rough surfaces in contact with different frictional coefficients and heat inputs under the thermal elasto-plastic contact conditions are studied.

A Two-Dimensional Adaptive Elasto-Plastic Contact Model of Rough Surfaces

2005 ◽  
Author(s):  
Tianxiang Liu ◽  
Geng Liu ◽  
Qin Xie
Keyword(s):  
Rough Surfaces ◽  
Computing Time ◽  
Surface Profile ◽  
Contact Problems ◽  
Contact Model ◽  
Computational Time ◽  
Real Contact Area ◽  
Asperity Contact ◽  
Pressure Distributions ◽  
Element Free

When contact problems are solved by numerical approaches, the surface profile is usually described by a series of discrete nodes with the same intervals along the coordinate axis. An adaptive-surface-based elasto-plastic asperity contact model is presented in this paper. Such a model is developed in order to reduce the computing time by removing the surface nodes that have little influence on the contact behavior of rough surfaces. The removed nodes are determined by setting a threshold. Thus, the contact problems can be described by fewer surface nodes but have similar results to the ones of the original surface. The adaptive asperity contact model is solved by using the element-free Galerkin-finite element (EFG-FE) coupling method because of its flexibility in domain descritization and versatility in node arrangements. The effects of different thresholds on the contact pressure distributions, real contact area, and the elasto-plastic stress fields in the contacting bodies are investigated and discussed. The results show that the computational time will dramatically reduce to about 50% when the relative error is about 5%.

A New Adaptive-Surface Elastic-Plastic Contact Model of Rough Surfaces: Parameter Correlations

2006 ◽  
Vol 532-533 ◽  
pp. 961-964
Author(s):  
Min Song
Keyword(s):  
Rough Surface ◽  
Root Mean Square ◽  
Rough Surfaces ◽  
Computing Time ◽  
Contact Model ◽  
Asperity Contact ◽  
Mean Square ◽  
Elastic Plastic ◽  
Surface Profiles

Based on an presented adaptive-surface elastic-plastic asperity contact model which can greatly decrease contact computing time and keep the precision loss less than 5%, a series of 2-D rough surface profiles with different roughness and correlative length are numerically generated to investigate how to select the threshold used in this model for different adaptive rough surfaces. The results show that well acceptable precision of the elastic-plastic contact calculation would be derived when the ratio of threshold to root mean square curvature, δ 1.0 10 6mm2 − < × .

Approximate Macroscale Constitutive Relations Using a Finite Element Based Constitutive Equations for Microscale Contact

2008 ◽  
Author(s):  
Ali Sepehri ◽  
Kambiz Farhang
Keyword(s):  
Finite Element ◽  
Contact Force ◽  
Rough Surfaces ◽  
Constitutive Relations ◽  
Cumulative Effect ◽  
Element Model ◽  
Tangential Component ◽  
Total Force ◽  
Asperity Contact ◽  
Elastic Plastic

Three dimensional elastic-plastic contact of two nominally flat rough surfaces is considered. Equations governing the shoulder-shoulder contact of asperities are derived based on the asperity-asperity constitutive relations from a finite element model of their elastic-plastic interaction. Shoulder-shoulder asperity contact yields a slanted contact force consisting of both tangential (parallel to mean plane) and normal components. Multiscale modeling of the elastic-plastic rough surface contact is presented in which asperity-level FE-based constitutive relations are statistically summed to obtain total force in the normal and tangential direction. The equations derived are in the form of integral functions and provide expectation of contact force components between two rough surfaces. An analytical fusion technique is developed to combine the piecewise asperity level constitutive relations. This is shown to yield upon statistical summation the cumulative effect resulting in the contact force between two rough surfaces with two components, one in the normal direction and a half-plane tangential component.

Contact Mechanics of Rough Surfaces in Tribology: Single Asperity Contact

1996 ◽  
Vol 49 (5) ◽  
pp. 275-298 ◽  
Author(s):  
Bharat Bhushan
Keyword(s):  
Friction And Wear ◽  
Rough Surfaces ◽  
Asperity Contact ◽  
Elastic Solids ◽  
Elastic Plastic ◽  
Single Asperity ◽  
Real Area Of Contact ◽  
Single Asperity Contact ◽  
Indentation Problem ◽  
Real Area

Contact modeling of two rough surfaces under normal approach and with relative motion is carried out to predict the real area of contact which affects friction and wear of an interface. The contact of two macroscopically flat bodies with microroughness is reduced to the contact at multiple asperities of arbitrary shapes. Most of deformation at the asperity contact can be either elastic or elastic-plastic. In this paper, a comprehensive review of modeling of a single asperity contact or an indentation problem is presented. Contact analyses for a spherical asperity/indenter on homogeneous and layered, elastic and elastic-plastic solids with and without tangential loading are presented. The analyses reviewed in this paper fall into two groups: (a) analytical solutions, primarily for elastic solids and (b) finite element solutions, primarily for elastic-plastic problems and layered solids. Implications of these analyses in friction and wear are discussed.

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.

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