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.

Comparative Contact Analysis Study of Finite Element Method Based Deterministic, Simplified Multi-Asperity and Modified Statistical Contact Models

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
A. Megalingam ◽  
M. M. Mayuram
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Rough Surface ◽  
Contact Area ◽  
Model Analysis ◽  
Contact Model ◽  
Contact Load ◽  
Asperity Contact ◽  
Single Asperity ◽  
Contact Models

The study of the contact stresses generated when two surfaces are in contact plays a significant role in understanding the tribology of contact pairs. Most of the present contact models are based on the statistical treatment of the single asperity contact model. For a clear understanding about the elastic-plastic behavior of two rough surfaces in contact, comparative study involving the deterministic contact model, simplified multi-asperity contact model, and modified statistical model are undertaken. In deterministic contact model analysis, a three dimensional deformable rough surface pressed against a rigid flat surface is carried out using the finite element method in steps. A simplified multi-asperity contact model is developed using actual summit radii deduced from the rough surface, applying single asperity contact model results. The resultant contact parameters like contact load, contact area, and contact pressure are compared. The asperity interaction noticed in the deterministic contact model analysis leads to wide disparity in the results. Observing the elastic-plastic transition of the summits and the sharing of contact load and contact area among the summits, modifications are employed in single asperity statistical contact model approaches in the form of a correction factor arising from asperity interaction to reduce the variations. Consequently, the modified statistical contact model and simplified multi-asperity contact model based on actual summit radius results show improved agreement with the deterministic contact model results.

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%.

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.

Review on Rock Joint Contact Model

2012 ◽  
Vol 170-173 ◽  
pp. 232-236
Author(s):  
Li Fang Zou ◽  
Wei Jie Deng
Keyword(s):  
Interaction Effect ◽  
Rough Surfaces ◽  
Rock Joint ◽  
Contact Problems ◽  
Contact Model ◽  
Normal Loading ◽  
Multi Scale ◽  
Scale Models ◽  
Joint Contact ◽  
Contact Models

The contact of nominally flat rough surfaces can be applied in rock joint contact problems. Statistical, fractal and multi-scale models for surfaces under normal loading are reviewed. The assumptions usually used in those contact models are illustrated. The criteria for distinguishing surfaces which touch elastically from those which touch plastically are analyzed. Moreover, the interaction effect of asperities under loading is discussed.

scholarly journals A Cylindrical Contact Model for Two-Dimensional Multiasperity Profiles

2003 ◽  
Author(s):  
John J. Jagodnik ◽  
Sinan Mu¨ftu¨
Keyword(s):  
Three Dimensional ◽  
Local Maximum ◽  
Contact Problems ◽  
Pressure Profile ◽  
Contact Model ◽  
Total Force ◽  
Asperity Contact ◽  
Two Dimensional ◽  
Depth Direction ◽  
Contact Parameters

In practice, multi-asperity contact problems are often solved as two dimensional (2D) plane problems rather than true three dimensional (3D) problems. This is accomplished by assuming that each peak on a 2D scanned profile is the pinnacle of a half sphere. Hertz contact equations are then used to solve for the radius of contact and pressure profile. In reality, the local maximum in the plane may not be the maximum in the unmeasured depth direction, creating inherent errors in the contact model. This error is shown to be significant in contact problems when estimating the area of contact and total contact force over a single asperity. The pressure corrected Sternberg-Turteltaub model is introduced, in which a cylinder is used to model a sphere in a plane. This model is shown to improve the contact area and total force estimates for a range contact parameters.

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%.

scholarly journals Numerical prediction of the frictional losses in sliding bearings during start-stop operation

Friction ◽  
2020 ◽  
Author(s):  
Florian König ◽  
Christopher Sous ◽  
Georg Jacobs
Keyword(s):  
Detailed Comparison ◽  
Numerical Prediction ◽  
Contact Model ◽  
Engineering Practice ◽  
Asperity Contact ◽  
Sliding Bearings ◽  
Actual Distribution ◽  
Automotive Engine ◽  
Frictional Losses ◽  
Contact Models

AbstractWith the increased use of automotive engine start-stop systems, the numerical prediction and reduction of frictional losses in sliding bearings during starting and stopping procedures has become an important issue. In engineering practice, numerical simulations of sliding bearings in automotive engines are performed with statistical asperity contact models with empirical values for the necessary surface parameters. The aim of this study is to elucidate the applicability of these approaches for the prediction of friction in sliding bearings subjected to start-stop operation. For this purpose, the friction performance of sliding bearings was investigated in experiments on a test rig and in transient mixed elasto-hydrodynamic simulations in a multi-body simulation environment (mixed-EHL/MBS). In mixed-EHL/MBS, the extended Reynold’s equation with flow factors according to Patir and Cheng has been combined on the one hand with the statistical asperity contact model according to Greenwood and Tripp and on the other hand with the deterministic asperity contact model according to Herbst. The detailed comparison of simulation and experimental results clarifies that the application of statistical asperity contact models with empirical values of the necessary inputs leads to large deviations between experiment and simulation. The actual distribution and position of surface roughness, as used in deterministic contact modelling, is necessary for a reliable prediction of the frictional losses in sliding bearings during start-stop operation.

scholarly journals The effect of sampling interval on the predictions of an asperity contact model of two-process surfaces

2017 ◽  
Vol 65 (3) ◽  
pp. 391-398 ◽  
Author(s):  
P. Pawlus ◽  
R. Reizer ◽  
M. Wieczorowski ◽  
W. Żelasko
Keyword(s):  
Surface Region ◽  
Sampling Interval ◽  
Plasticity Index ◽  
Contact Model ◽  
Asperity Contact ◽  
Normal Contact ◽  
Method Of Calculation ◽  
Surface Separation ◽  
Sampling Intervals ◽  
Flat Steel

AbstractContact of random machined two-process steel textures with a smooth, flat steel surface is discussed in this paper. Two-process surfaces were machined by vapour blasting followed by lapping. An elastic-plastic contact model was applied, assuming distributed radius of asperities. Calculation procedures allowed the mean surface separation, contact pressure, and area fraction to be computed as functions of sampling intervals. Parameters characterizing the summits important in contact mechanics were calculated for different sampling intervals. Plasticity index of two-process textures was calculated using the modified procedure. It was found that the influence of sampling interval on normal contact depended on the rough surface ability to plastic deformation. The use of a traditional method of calculation overestimated the plasticity index. Peaks from plateau surface region governed contact characteristics of two-process surfaces.

Investigation of the Influence of Different Asperity Contact Models on the Elastohydrodynamic Analysis of a Conrod Small-End/Piston Pin Coupling

2018 ◽  
Vol 11 (6) ◽  
pp. 919-934 ◽  
Author(s):  
Andrea Ferretti ◽  
Matteo Giacopini ◽  
Luca Mastrandrea ◽  
Daniele Dini
Keyword(s):  
Asperity Contact ◽  
Contact Models
Sign in / Sign up

Export Citation Format

Share Document