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%.

Two-Dimensional Adaptive-Surface Elasto-Plastic Asperity Contact Model

2006 ◽  
Vol 128 (4) ◽  
pp. 898-903 ◽  
Author(s):  
Tianxiang Liu ◽  
Geng Liu ◽  
Qin Xie ◽  
Q. Jane Wang
Keyword(s):  
Computing Time ◽  
Surface Profile ◽  
Contact Problems ◽  
Contact Model ◽  
Computational Time ◽  
Real Contact Area ◽  
Asperity Contact ◽  
Relative Errors ◽  
Domain Discretization ◽  
Element Free

When contact problems are solved by numerical approaches, a surface profile is usually described by a series of discrete nodes with the same intervals along a coordinate axis. Contact computation based on roughness datum mesh may be time consuming. An adaptive-surface 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 nodes to be removed are determined by a prescribed threshold. The adaptive-surface asperity contact model is solved by means of the element-free Galerkin-finite element coupling method because of its flexibility in domain discretization and versatility in node arrangements. The effects of different thresholds on contact pressure distribution, real contact area, and elasto-plastic stress fields in contacting bodies are investigated and discussed. The results show that this model can help reduce about 48% computational time when the relative errors are about 5%.

Contact Simulation of Three-Dimensional Rough Surfaces Using Moving Grid Method

1993 ◽  
Vol 115 (4) ◽  
pp. 597-601 ◽  
Author(s):  
Ning Ren ◽  
Si C. Lee
Keyword(s):  
Rough Surfaces ◽  
Computing Time ◽  
Three Dimensional ◽  
Random Access ◽  
Grid Method ◽  
Contact Problems ◽  
Computational Time ◽  
Moving Grid ◽  
Memory Size ◽  
Surface Profiles

A new method for simulating dry contacts of three-dimensional rough surfaces has been developed. The present work is based upon Moving Grid Method (MGM) which greatly reduces the required computer memory size. One of the major difficulties in simulating contact problems is the huge requirement in computer Random Access Memory (RAM). The total number of nodes (N) to represent a typical three dimensional roughness topography can easily be in the order of tens of thousands. To store the corresponding deformation matrix based on conventional matrix method requires memory size in the order of N2. The computational time necessary to construct such a matrix is also proportional to N2. Thus a reasonable solution for the three dimensional contact problem can be difficult to obtain. In Moving Grid Method, the required storage space for the deformation matrix is reduced to the order of N. The computing time to construct the matrix is also proportional to N. The contact simulation solutions which include the asperity pressure distributions and the corresponding deformed surface profiles were calculated. The digitized surface profiles were used in the simulations. The 3-D results were compared with an existing 2-D model and the comparison showed excellent agreement.

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.

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 − < × .

A New Approach to Calculation of Contact Characteristics

1999 ◽  
Vol 121 (1) ◽  
pp. 20-27 ◽  
Author(s):  
O. G. Chekina ◽  
L. M. Keer
Keyword(s):  
Rough Surfaces ◽  
Contact Region ◽  
Contact Problems ◽  
Surface Shape ◽  
Real Contact Area ◽  
Iteration Algorithm ◽  
Normal Contact Stress ◽  
Normal Contact ◽  
The Real ◽  
Integral Relations

A new method of calculation of contact characteristics for rough surfaces is proposed based on integral relations that express the normal contact stress as an explicit function of the surface shape. To produce calculations by this method, a region having a simple shape should be chosen first, where the contact is supposed to be nominally complete. An iterative procedure with regard to the shape is applied within the load-free surface portion, and allows the normal stresses, surface displacement and the real area of contact to be determined. The method is applicable to rough bodies of arbitrary shape for which the half-space formulation and equivalent roughness concepts apply; the real contact area should lie within the initially chosen contact region and can include a system of unconnected contact spots. Both 2D and 3D cases are considered in the present work. The 2D analysis is based on known integral relations for nonperiodic and periodic contact problems. In the 3D case, new analytical relations are obtained and their properties are analyzed. An iteration algorithm based on these relations and its efficient numerical implementation are described. Application of the method to the contact of real rough surfaces is discussed.

Stratified Revised Asperity Contact Model for Worn Surfaces

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Songtao Hu ◽  
Noel Brunetiere ◽  
Weifeng Huang ◽  
Xiangfeng Liu ◽  
Yuming Wang
Keyword(s):  
Deterministic Model ◽  
Contact Problems ◽  
Contact Model ◽  
Asperity Contact ◽  
Knee Point ◽  
Gaussian Representation ◽  
Contact Models ◽  
Large Roughness ◽  
Gaussian Surface ◽  
Worn Surfaces

Segmented bi-Gaussian stratified elastic asperity contact model of Leefe (1998, “‘Bi-Gaussian’ Representation of Worn Surface Topography in Elastic Contact Problems,” Tribol. Ser., 34, pp. 281–290), which suits for worn surfaces, has been improved. It still exhibits two drawbacks: (1) the arbitrary assumption of the probability density function (PDF) consisting of two component PDFs intersecting at a knee-point, violating the unity-area demand and (2) the preference for large roughness-scale part of the surface, leading to an error on the characterization of small roughness-scale part. A continuous bi-Gaussian stratified elastic asperity contact model is proposed based on a surface combination theory and a continuous separation method. The two stratified contact models are applied to a simulated pure bi-Gaussian surface and four real worn surfaces. The results show that the modified segmented and the continuous stratified contact models are both validated by a deterministic model with better accuracy for the continuous one.

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 &gt; 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 &lt; ψ &lt; 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.

A FEM Based Multiple Asperity Deterministic Contact Model

2009 ◽  
Author(s):  
A. Megalingam ◽  
M. M. Mayuram
Keyword(s):  
Friction And Wear ◽  
Statistical Approach ◽  
Present Model ◽  
Contact Model ◽  
Real Contact Area ◽  
Clear Understanding ◽  
Asperity Contact ◽  
Single Asperity ◽  
Contact Models ◽  
Single Asperity Contact

Knowledge of contact stresses generated when two surfaces are in contact play a significant role in understanding most mechanisms of friction and wear. Most of present contact models are based on the Greenwood-Williamson (GW) single asperity contact model and a statistical approach is adopted to calculate the real contact area for the entire surface based on the assumption that all the summits have uniform radius of curvatures and their heights vary randomly. But in real cases, the asperity radii vary. For a clear understanding about those aspects, a multiple asperity contact model, based on 3-D rough surface generated is analyzed using a commercial FEM package. Salient aspects of the present model are presented here and results are compared with a single asperity contact model.

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.

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