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.

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.

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.

Model for Elastic–Plastic Contact Between Rough Surfaces

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Zhiqian Wang ◽  
Xingna Liu
Keyword(s):  
Rough Surfaces ◽  
Plasticity Index ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Single Asperity ◽  
Deformation Regime ◽  
Smooth Model ◽  
Relationship Of ◽  
The Relationship ◽  
Contact Displacement

This paper studies elastic–plastic contact between Greenwood–Williamson (GW) rough surfaces, on which there are many asperities with the same radius whose height obeys the Gaussian distribution. A new plasticity index is defined as the ratio of the standard deviation of the height of asperities on the rough surface to the single-asperity critical displacement (the transition point from the elastic to the elastic-fully plastic deformation regime), which is linearly proportional to the GW plasticity index to the power of 2. The equations for the load/area–separation relationship of rough surfaces are presented based on Wang and Wang's smooth model of singe-asperity elastic–plastic contact, which is an improvement of the Kogut–Etsion (KE) empirical model based on finite element analysis (FEA) data. The load/area–separation relationship can be described by empirical Gaussian functions. The load–area relationship of rough surfaces is approximately linear. The average pressure is only function of the new plasticity index. According to Wang and Wang's conclusion that Etsion et al. single-asperity elastic–plastic loading (EPL) index is approximately equal to the ratio of the single-asperity residual plastic contact displacement to the single-asperity total elastic–plastic contact displacement, the equations for the relationship between Kadin et al. modified plasticity index (MPI) and separation of rough surfaces are also presented. In addition, the MPI is approximately linearly proportional to the separation between rough surfaces for a given new plasticity index ranging from 5 to 30. When the new plasticity index is smaller than 5, due to the large proportion of the elastic deformation in the total deformation, the MPI slightly deviate from linearity.

Elastic-Plastic Adhesive Contact of Rough Surfaces Based on Accurate FEA Study Using N-Point Asperity Model

2014 ◽  
Vol 2 (2) ◽  
pp. 1-22
Author(s):  
Ajay K. Waghmare ◽  
Prasanta Sahoo
Keyword(s):  
Plastic Deformation ◽  
Rough Surfaces ◽  
Adhesive Contact ◽  
Plasticity Index ◽  
Asperity Contact ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Significant Difference ◽  
Asperity Model ◽  
Adhesion Index

The paper describes a theoretical study of elastic-plastic adhesive contact of rough surfaces based on n-point asperity model and accurate finite element analysis (FEA) of elastic-plastic deformation of single asperity contact. The n-point asperity model developed by Hariri et al (2006) is integrated with the elastic-plastic model of . In this study an attempt is made to extend the work of by incorporating intermediate elastic-plastic regime of deformation. A large range of interference values ranging from fully elastic through elastic-plastic to fully plastic deformation of contacting asperities is considered. The effect of varying load and material parameters is analyzed in terms of well established adhesion index and plasticity index. A comparison between the present analysis with that of model shows significant difference in load–separation behaviour depending on combinations of mean separation, adhesion index and plasticity index.

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.

Adhesive Wear Based on Accurate FEA Study of Asperity Contact and n-Point Asperity Model

2016 ◽  
Vol 4 (1) ◽  
pp. 1-24
Author(s):  
Ajay K. Waghmare ◽  
Prasanta Sahoo
Keyword(s):  
Adhesive Wear ◽  
Complete Solution ◽  
Wear Particle ◽  
Wear Volume ◽  
Asperity Contact ◽  
Wear Model ◽  
Element Analysis ◽  
Particle Generation ◽  
Elastic Plastic ◽  
Asperity Model

The paper describes a theoretical study of adhesive wear based on accurate finite element analysis (FEA) of elastic-plastic contact of single asperity and n-point asperity model. The wear model developed considers wear particle generation in whole range of deformation, ranging from fully elastic through elastic-plastic to fully plastic. Well defined adhesion index and plasticity index are used to study the prospective situations arising out of variation in load, material properties, and surface roughness. It is observed that the wear volume at particular level of separation increases with increase in plastic deformation and adhesion effect. Materials having higher tendency to adhesion show higher wear rate. Trend of the results obtained is found in line with the existing solutions which are modeled with conventional asperity concept. Inclusion of separate formulations for intermediate state of deformation of asperities which are based on accurate FEA study gives complete solution.

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 A Finite Element-Based Elastic-Plastic Model for the Contact of Rough Surfaces

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Ali Sepehri ◽  
Kambiz Farhang
Keyword(s):  
Finite Element ◽  
Contact Force ◽  
Contact Area ◽  
Rough Surfaces ◽  
Constitutive Relations ◽  
Element Model ◽  
Tangential Component ◽  
Asperity Contact ◽  
Elastic Plastic ◽  
Force Components

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 constitutive relations from a finite element model of the elastic-plastic interaction proposed by Kogut and Etsion (2002), in which asperity scale constitutive relations are derived using piecewise approximate functions. An analytical fusion technique is developed to combine the piecewise asperity level constitutive relations. Shoulder-shoulder asperity contact yields a slanted contact force consisting of two components, one in the normal direction and a half-plane tangential component. Statistical summation of the asperity level contact force components and asperity level contact area results in the total contact force and total contact area formulae between two rough surfaces. Approximate equations are developed in closed form for contact force components and contact area.

Closed-Form Equations for Three Dimensional Elastic-Plastic Contact of Nominally Flat Rough Surfaces

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Ali Sepehri ◽  
Kambiz Farhang
Keyword(s):  
Closed Form ◽  
Contact Force ◽  
Rough Surfaces ◽  
Tangential Force ◽  
Three Dimensional ◽  
Tangential Direction ◽  
Asperity Contact ◽  
Force Component ◽  
Elastic Plastic ◽  
Functional Forms

Approximate closed-form equations governing the shoulder-shoulder contact of asperities are derived based on a generalization by Chang, Etsion, and Bogy. The work entails the consideration of asperity shoulder-shoulder contact in which the volume conservation is assumed in the plastic flow regime. Shoulder-shoulder asperity contact gives rise to a slanted contact force comprising tangential and normal components. Each force component comprises elastic and plastic terms, which upon statistical summation yields the force component for the elastic and plastic forces for the contact of two rough surfaces. Half-plane tangential force due to elastic-plastic contact is derived through the statistical summation of tangential force component along an arbitrary tangential direction. Two sets of equations are found. In the first set of equations the functional forms are simpler and provide approximation of contact force to within 9%. The second set is enhanced equations derived from the first set of approximate equations that achieve an accuracy of within 0.2%.

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