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.

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.

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.

Friction Reduction Effect of Soft Coatings

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Zhou Chen
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Static Friction ◽  
Hard Coatings ◽  
Friction Reduction ◽  
Element Analysis ◽  
Tangential Load ◽  
Static Friction Coefficient ◽  
Tangential Stiffness ◽  
Reduction Effect

Finite element analysis is conducted on an elastic-plastic full stick contact between a rigid flat and a deformable coated sphere with a soft coating. A combined normal and tangential load is applied to the rigid flat, and the sliding inception is assumed as a result of the decreasing tangential stiffness of the contact junction. As the coating becomes thicker, the static friction coefficient first decreases reaching a minimum and then increases. This demonstrates a friction reduction effect of soft coatings that is opposite to hard coatings. The static friction coefficient decreases with increasing normal load as the contact junction contains more plasticity and becomes more compliant.

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.

A Static Friction Model for Elastic-Plastic Contacting Rough Surfaces

2004 ◽  
Vol 126 (1) ◽  
pp. 34-40 ◽  
Author(s):  
Lior Kogut ◽  
Izhak Etsion
Keyword(s):  
Friction Coefficient ◽  
Rough Surfaces ◽  
Static Friction ◽  
Friction Model ◽  
Plasticity Index ◽  
High Plasticity ◽  
Elastic Plastic ◽  
Static Friction Coefficient ◽  
Contact Adhesion ◽  
Limiting Case

A model that predicts the static friction for elastic-plastic contact of rough surfaces is presented. The model incorporates the results of accurate finite element analyses for the elastic-plastic contact, adhesion and sliding inception of a single asperity in a statistical representation of surface roughness. The model shows strong effect of the external force and nominal contact area on the static friction coefficient in contrast to the classical laws of friction. It also shows that the main dimensionless parameters affecting the static friction coefficient are the plasticity index and adhesion parameter. The effect of adhesion on the static friction is discussed and found to be negligible at plasticity index values larger than 2. It is shown that the classical laws of friction are a limiting case of the present more general solution and are adequate only for high plasticity index and negligible adhesion. Some potential limitations of the present model are also discussed pointing to possible improvements. A comparison of the present results with those obtained from an approximate CEB friction model shows substantial differences, with the latter severely underestimating the static friction coefficient.

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