Experimental study of the effect of dwell time and normal load on static friction in creeping elastic–plastic polymer spherical contact

Wear ◽  
2014 ◽  
Vol 309 (1-2) ◽  
pp. 139-145 ◽  
Author(s):  
H. Kasem ◽  
I. Etsion
Keyword(s):  
Experimental Study ◽  
Dwell Time ◽  
Normal Load ◽  
Static Friction ◽  
Spherical Contact ◽  
Elastic Plastic

The Effect of Surface Roughness on Static Friction and Junction Growth of an Elastic-Plastic Spherical Contact

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
D. Cohen ◽  
Y. Kligerman ◽  
I. Etsion
Keyword(s):  
Surface Roughness ◽  
Normal Load ◽  
Static Friction ◽  
Threshold Value ◽  
Real Contact Area ◽  
Surface Model ◽  
Spherical Contact ◽  
Elastic Plastic ◽  
Surface Models ◽  
Effect Of Surface

A model for elastic-plastic spherical contact of rough surfaces under combined normal and tangential loadings, with full stick contact condition, is presented. The model allows evaluation of the effect of surface roughness on the real contact area, static friction and junction growth under small normal loads. It is shown that as the normal load approaches a certain threshold value, which depends on the plasticity index, the results of the present rough surface model approach these of previous corresponding models for smooth sphere and a rigid flat. At normal load values below the threshold load, the correlation of the present results and published experimental results is much better in comparison with the results of the smooth surface models.

Experimental Study of Static Friction in a Spherical Elastic-Plastic Contact

2008 ◽  
Author(s):  
Andrey Ovcharenko ◽  
Gregory Halperin ◽  
Izhak Etsion
Keyword(s):  
Friction Force ◽  
Normal Load ◽  
Static Friction ◽  
Tangential Displacement ◽  
Accurate Identification ◽  
Elastic Plastic ◽  
Static Friction Coefficient ◽  
Wide Range ◽  
Material Good ◽  
Contact Diameter

The elastic-plastic contact between a deformable sphere and a rigid flat during pre-sliding is studied experimentally. Measurements of friction force and contact area are done in real time along with an accurate identification of the instant of sliding inception. The static friction force and relative tangential displacement are investigated over a wide range of normal preloads for several sphere materials and diameters. It is found that at low normal loads the static friction coefficient depends on the normal load in breach of the classical laws of friction. The pre-sliding displacement is found to be less than 5 percent of the contact diameter, and the interface mean shear stress at sliding inception is found to be slightly below the shear strength of the sphere material. Good correlation is found between the present experimental results and a recent theoretical model in the elastic-plastic regime of deformation.

Experimental Study of Adhesive Static Friction in a Spherical Elastic-Plastic Contact

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
A. Ovcharenko ◽  
G. Halperin ◽  
I. Etsion
Keyword(s):  
Friction Force ◽  
Normal Load ◽  
Static Friction ◽  
Tangential Displacement ◽  
Accurate Identification ◽  
Elastic Plastic ◽  
Static Friction Coefficient ◽  
Wide Range ◽  
Material Good ◽  
Contact Diameter

The elastic-plastic contact between a deformable sphere and a rigid flat during presliding is studied experimentally. Measurements of friction force and contact area are done in real time along with an accurate identification of the instant of sliding inception. The static friction force and relative tangential displacement are investigated over a wide range of normal preloads for several sphere materials and diameters. Different behavior of the static friction is observed in the elastic and in the elastic-plastic regimes of sphere deformation. It is found that at low normal loads, the static friction coefficient depends on the normal load in breach of the classical laws of friction. The presliding displacement is found to be less than 5% of the contact diameter, and the interface mean shear stress at sliding inception is found to be slightly below the shear strength of the sphere material. Good correlation is found between the present experimental results and a recent theoretical model in the elastic-plastic regime of deformation.

Pre-Sliding of a Spherical Elastic-Plastic Contact

2008 ◽  
Author(s):  
Andrey Ovcharenko ◽  
Gregory Halperin ◽  
Izhak Etsion
Keyword(s):  
Friction Force ◽  
Normal Load ◽  
Static Friction ◽  
Tangential Displacement ◽  
Accurate Identification ◽  
Elastic Plastic ◽  
Static Friction Coefficient ◽  
Wide Range ◽  
Material Good ◽  
Contact Diameter

The elastic-plastic contact between a deformable sphere and a rigid flat during pre-sliding is studied experimentally. Measurements of friction force and contact area are done in real time along with an accurate identification of the instant of sliding inception. The static friction force and relative tangential displacement are investigated over a wide range of normal preloads for several sphere materials and diameters. It is found that at low normal loads the static friction coefficient depends on the normal load in breach of the classical laws of friction. The pre-sliding displacement is found to be less than 5 percent of the contact diameter, and the interface mean shear stress at sliding inception is found to be slightly below the shear strength of the sphere material. Good correlation is found between the present experimental results and a recent theoretical model in the elastic-plastic regime of deformation.

The Evolution of Static Friction for Elastic-Plastic Spherical Contact in Pre-sliding

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
V. Zolotarevskiy ◽  
Y. Kligerman ◽  
I. Etsion
Keyword(s):  
Static Friction ◽  
Contact Condition ◽  
Spherical Contact ◽  
Elastic Plastic ◽  
Tangential Stiffness ◽  
Plastic Sphere ◽  
Dimensionless Equations

The evolution of static friction and tangential stiffness in presliding of an elastic-plastic sphere in contact with a rigid flat, under full stick contact condition, is analyzed. Empirical dimensionless equations are developed for these parameters.

Contact mechanics of elastic-plastic fractal surfaces and static friction analysis of asperity scale

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wujiu Pan ◽  
Xiaopeng Li ◽  
Xue Wang
Keyword(s):  
Plastic Deformation ◽  
Fractal Dimension ◽  
Friction Coefficient ◽  
Contact Mechanics ◽  
Normal Load ◽  
Boundary Value ◽  
Static Friction ◽  
Content Type ◽  
Elastic Plastic ◽  
Static Friction Coefficient

Purpose The purpose of this paper is to provide a static friction coefficient prediction model of rough contact surfaces based on the contact mechanics analysis of elastic-plastic fractal surfaces. Design/methodology/approach In this paper, the continuous deformation stage of the multi-scale asperity is considered, i.e. asperities on joint surfaces go through three deformation stages in succession, the elastic deformation, the elastic-plastic deformation (the first elastic-plastic region and the second elastic-plastic region) and the plastic deformation, rather than the direct transition from the elastic deformation to the plastic deformation. In addition, the contact between rough metal surfaces should be the contact of three-dimensional topography, which corresponds to the fractal dimension D (2 < D < 3), not two-dimensional curves. So, in consideration of the elastic-plastic deformation mechanism of asperities and the three-dimensional topography, the contact mechanics of the elastic-plastic fractal surface is analyzed, and the static friction coefficient nonlinear prediction model of the surface is further established. Findings There is a boundary value between the normal load and the fractal dimension. In the range smaller than the boundary value, the normal load decreases with fractal dimension; in the range larger than the boundary value, the normal load increases with fractal dimension. Considering the elastic-plastic deformation of the asperity on the contact surface, the total normal contact load is larger than that of ignoring the elastic-plastic deformation of the asperity. There is a proper fractal dimension, which can make the static friction of the contact surface maximum; there is a negative correlation between the static friction coefficient and the fractal scale coefficient. Originality/value In the mechanical structure, the research and prediction of the static friction coefficient characteristics of the interface will lay a foundation for the understanding of the mechanism of friction and wear and the interaction relationship between contact surfaces from the micro asperity-scale level, which has an important engineering application value.

Static Friction Experiments and Verification of an Improved Elastic-Plastic Model Including Roughness Effects

2007 ◽  
Vol 129 (4) ◽  
pp. 754-760 ◽  
Author(s):  
Chul-Hee Lee ◽  
Andreas A. Polycarpou
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Wear Debris ◽  
Normal Load ◽  
Static Friction ◽  
Displacement Rate ◽  
Experimental Measurements ◽  
Roughness Effects ◽  
Elastic Plastic ◽  
Static Friction Coefficient

An experimental study was conducted to measure the static friction coefficient under constant normal load and different interface conditions. These include surface roughness, dwell time, displacement rate, as well as the presence of traces of lubricant and wear debris at the interface. The static friction apparatus includes accurate measurement of friction, normal and lateral forces at the interface (using a high dynamic bandwidth piezoelectric force transducer), as well as precise motion control and measurement of the sliding mass. The experimental results show that dry surfaces are more dependent on the displacement rate prior to sliding inception compared to boundary lubricated surfaces in terms of static friction coefficient. Also, the presence of wear debris, boundary lubrication, and rougher surfaces decrease the static friction coefficient significantly compared to dry smooth surfaces. The experimental measurements under dry unlubricated conditions were subsequently compared to an improved elastic-plastic static friction model, and it was found that the model captures the experimental measurements of dry surfaces well in terms of the surface roughness.

A Semi-Analytical Solution for the Sliding Inception of a Spherical Contact

2003 ◽  
Vol 125 (3) ◽  
pp. 499-506 ◽  
Author(s):  
Lior Kogut ◽  
Izhak Etsion
Keyword(s):  
Friction Coefficient ◽  
Analytical Solution ◽  
Failure Modes ◽  
Static Friction ◽  
Element Analysis ◽  
Tangential Load ◽  
Spherical Contact ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

A finite element analysis, for an elastic perfectly plastic sphere normally loaded by a rigid flat, is combined with an approximate analytical solution to evaluate the maximum tangential load (static friction) that can be supported by the spherical contact at the inception of sliding. Sliding inception is treated as a failure mechanism based on plastic yield rather than a Coulomb friction law with a certain friction coefficient. Two different failure modes are identified, either on the contact area or below it, depending on the elastic-plastic status of the normal preloading. A limiting normal preload is found above which the contact cannot support any additional tangential load. Simple analytical expressions for an “internal static friction coefficient” are presented for both the elastic and the elastic-plastic regimes.

A Coupled Eulerian–Lagrangian Model for Sliding Inception of Elastic–Plastic Spherical Contact

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Haibo Zhang ◽  
Izhak Etsion
Keyword(s):  
Computing Time ◽  
Static Friction ◽  
Lagrangian Model ◽  
Convergence Problem ◽  
Lagrangian Models ◽  
Spherical Contact ◽  
Elastic Plastic ◽  
Static Friction Coefficient ◽  
Tangential Stiffness ◽  
Explicit Dynamic

Abstract Currently existing finite element (FE) Lagrangian models of elastic–plastic spherical contact are costly in terms of computing time to reach vanishing tangential stiffness at sliding inception. A coupled Eulerian–Lagrangian (CEL) model with explicit dynamic analysis and power-law hardening is proposed to resolve this problem. The CEL model also avoids convergence problem caused by excessive distortion of elements in Lagrangian models. Static friction coefficient at sliding inception is investigated and compared with available experimental results. It is found that the proposed new CEL model is more efficient and accurate compared to previously published results of Lagrangian models.

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