On the Modeling of Quasi-Steady and Unsteady Dynamic Friction in Sliding Lubricated Line Contact

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
H. Sojoudi ◽  
M. M. Khonsari
Keyword(s):  
Experimental Data ◽  
Friction Coefficient ◽  
Reynolds Equation ◽  
Friction Model ◽  
Sliding Contact ◽  
Dynamic Friction ◽  
Line Contact ◽  
Sliding Velocity ◽  
Friction Behavior ◽  
Lubricated Sliding

A simple but realistic dynamic friction model for the lubricated sliding contact is developed based on decoupling the steady and unsteady terms in Reynolds equation. The model realistically captures the physics of friction behavior both when speed is increased unidirectionally or when operating under oscillating condition. The model can simulate the transition from boundary to mixed to full film regimes as the speed is increased. Two different classes of simulations are performed to show the utility of the model: the so-called quasisteady, where the sliding velocity is varied very slowly, and the oscillating sliding velocity, where the friction coefficient exhibits a hysteresis type behavior. Both categories of simulation are verified by comparing the results with published experimental data.

Adhesive Effects on Dynamic Friction for Unlubricated Rough Planar Surfaces

2004 ◽  
Author(s):  
Xi Shi ◽  
Andreas A. Polycarpou
Keyword(s):  
Friction Coefficient ◽  
Mean Value ◽  
Friction Model ◽  
Major Influence ◽  
Dynamic Friction ◽  
Friction Behavior ◽  
Friction Forces ◽  
Normal Contact ◽  
Continuous Contact ◽  
Dynamic Friction Coefficient

As the size of contacting and sliding tribosystems decrease, intermolecular or adhesive forces become significant partly due to nanometer size surface roughness. The presence of adhesion has a major influence on the interfacial contact and friction forces as well as the microtribosystem dynamics and thus influences the overall dynamic friction behavior. In this paper, a dynamic friction model that explicitly includes adhesion, interfacial damping and the system dynamics for realistic rough surfaces was developed. The results show that the amplitude and mean value of the time varying normal contact and friction forces increase in the presence of adhesion under continuous contact conditions. Also, due to the attractive nature of adhesion, its presence delays or eliminates the occurrence of loss of contact. Furthermore, in the presence of significant adhesion, dynamic friction behavior is significantly more complicated compared to the no adhesion case, and the dynamic friction coefficient predictions may be misleading. Thus, it is more appropriate to discuss dynamic friction force instead of dynamic friction coefficient under dynamic conditions.

Adhesive Effects on Dynamic Friction for Unlubricated Rough Planar Surfaces

2006 ◽  
Vol 128 (4) ◽  
pp. 841-850 ◽  
Author(s):  
Xi Shi ◽  
Andreas A. Polycarpou
Keyword(s):  
Friction Coefficient ◽  
Mean Value ◽  
Friction Model ◽  
Major Influence ◽  
Dynamic Friction ◽  
Friction Behavior ◽  
Friction Forces ◽  
Normal Contact ◽  
Continuous Contact ◽  
Dynamic Friction Coefficient

As the size of contacting and sliding tribosystems decrease, intermolecular or adhesive forces become significant partly due to nanometer size surface roughness. The presence of adhesion has a major influence on the interfacial contact and friction forces as well as the microtribosystem dynamics (microtribodynamics) and thus influences the overall dynamic friction behavior. In this paper, a dynamic friction model that explicitly includes adhesion, interfacial damping, and the system dynamics for realistic rough surfaces was developed. The results show that the amplitude and mean value of the time varying normal contact and friction forces increase in the presence of adhesion under continuous contact conditions. Also, due to the attractive nature of adhesion, its presence delays or eliminates the occurrence of loss of contact. Furthermore, in the presence of significant adhesion, dynamic friction behavior is significantly more complicated compared to the no adhesion case, and the dynamic friction coefficient predictions may be misleading. Thus, it is more appropriate to discuss dynamic friction force instead of dynamic friction coefficient under dynamic conditions.

An improved nonlinear model considering relative velocity for the friction behavior between untwisted glass-fiber tow and roller

2021 ◽  
pp. 004051752110308
Author(s):  
Yang Liu ◽  
Zhong Xiang ◽  
Xiangqin Zhou ◽  
Zhenyu Wu ◽  
Xudong Hu
Keyword(s):  
Friction Coefficient ◽  
Glass Fiber ◽  
Relative Velocity ◽  
Friction Model ◽  
Woven Fabric ◽  
Test Results ◽  
Application Process ◽  
Friction Behavior ◽  
Improved Model

Friction between the tow and tool surface normally happens during the tow production, fabric weaving, and application process and has an important influence on the quality of the woven fabric. Based on this fact, this paper studied the influence of tension and relative velocity on the three kinds of untwisted-glass-fiber tow-on-roller friction with a Capstan-based test setup. Furthermore, an improved nonlinear friction model taking both tension and velocity into account was proposed. According to statistical test results, firstly, the friction coefficient was found to be positively correlated with tension and relative velocity. Secondly, tension and velocity were complementary on the tow-on-roller friction behavior, with neither being superior to the other. Thirdly, an improved model was found to present well the nonlinear characteristics between friction coefficient and tension and velocity, and predicational results of the model were found to agree well with the observations from Capstan tests.

Viscous Friction Effect During the Process of Tightening and Loosening of Bolted Joints

2021 ◽  
Author(s):  
Qingyuan Lin ◽  
Yong Zhao ◽  
Qingchao Sun ◽  
Kunyong Chen
Keyword(s):  
Friction Coefficient ◽  
Viscous Friction ◽  
Normal Pressure ◽  
Friction Model ◽  
Bolted Joints ◽  
Critical Parameters ◽  
Bolted Joint ◽  
Sliding Velocity ◽  
Friction Effect ◽  
Bearing Friction

Abstract Bolted connection is one of the most widely used mechanical connections because of its easiness of installation and disassembly. Research of bolted joints mainly focuses on two aspects: high precision tightening and improvement of anti-loosening performance. The under-head bearing friction coefficient and the thread friction coefficient are the two most important parameters that affect the tightening result of the bolted joint. They are also the most critical parameters that affect the anti-loosening performance of the bolted joint. Coulomb friction model is a commonly used model to describe under-head bearing friction and thread friction, which considers the friction coefficient as a constant independent of normal pressure and relative sliding velocity. In this paper, the viscous effect of the under-head bearing friction and thread friction is observed by measuring the friction coefficient of bolted joints. The value of the friction coefficient increases with the increase of the relative sliding velocity and the decrease of the normal pressure. It is found that the Coulomb viscous friction model can better describe the friction coefficient of bolted joints. Taking into account the dense friction effect, the loosening prediction model of bolted joints is modified. The experimental results show that the Coulomb viscous friction model can better describe the under-head bearing friction coefficient and thread friction coefficient. The model considering the dense effect can more accurately predict the loosening characteristics of bolted joints.

Numerical Investigation of Size Effect on Dry Friction Behavior in Micro Upsetting Process

2014 ◽  
Vol 997 ◽  
pp. 321-324
Author(s):  
Wei Zheng ◽  
Guang Chun Wang ◽  
Bing Tao Tang ◽  
Xiao Juan Lin ◽  
Yan Zhi Sun
Keyword(s):  
Friction Coefficient ◽  
Size Effect ◽  
Dry Friction ◽  
Normal Pressure ◽  
Friction Model ◽  
Strain Hardening Exponent ◽  
Forming Process ◽  
Friction Behavior ◽  
Initial Yield Stress ◽  
Coulomb’S Friction

After modifying the Wahime/Bay friction model, a new friction model suitable for micro-forming process without lubrication is established. In this model, it is shows that the friction coefficient is a function of strain hardening exponent, the normal pressure and the initial yield stress of material. Based on the experimental data, the micro-upsetting process is simulated using the proposed friction model. The simulation results are used to investigate the size effect on the dry friction behavior. It is found that the Coulomb’s friction coefficient is dropping with miniaturization of specimens when the amount of reduction is not too large.

Adhesive and normal stress-dependent dynamic friction of a gelatin hydrogel

2021 ◽  
pp. 135065012110446
Author(s):  
Nitish Sinha ◽  
Arun Kumar Singh ◽  
Vinit Gupta ◽  
Jitendra Kumar Katiyar
Keyword(s):  
Experimental Data ◽  
Normal Stress ◽  
Scaling Law ◽  
Shear Velocity ◽  
Friction Model ◽  
Dynamic Friction ◽  
Practical Applications ◽  
Soft Solids ◽  
Gelatin Hydrogel ◽  
Stress Dependent

Adhesion and friction of soft solids on hard surfaces are the important properties for a variety of practical applications. In the present study, Coulomb's law of friction is used for characterizing adhesive friction as well as normal stress-dependent dynamic friction of a gelatin hydrogel on a fixed glass surface. The experimental data, concerning normal stress-dependent dynamic friction of different shear velocity, are obtained from literature. It is observed that both components of friction increase with shear velocity. More importantly, the scaling law shows that adhesive stress varies almost linearly with corresponding coefficient of friction of the hydrogel. A dynamic friction model is also used to analyze the same experimental data to predict a negative normal stress at which dynamic friction reduces to zero, and this result matches closely with the experimental value.

scholarly journals 3D Numerical study on the effect of shaft eccentricity on the tribological performance of lubricated sliding contact

2018 ◽  
Vol 159 ◽  
pp. 02042
Author(s):  
Mohammad Tauviqirrahman ◽  
Bayu Kurniawan ◽  
Jamari
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Numerical Study ◽  
Wall Slip ◽  
Sliding Contact ◽  
Eccentricity Ratio ◽  
3D Numerical Modelling ◽  
Hydrodynamic Journal Bearing ◽  
Wedge Effect ◽  
Lubricated Sliding

Recently, a growing interest is given to the wall slip and the artificial texturing for improving the performance of lubricated sliding contact. The use of wall slip, artificial texturing, and the combination of slip and texturing can be the effective approach to enhance the performance of the bearing. The present study examines the effect of shaft eccentricity ratio on the hydrodynamic journal bearing performance. 3D numerical modelling based on modified Reynolds equation is used to analyse the effect of texturing and the wall slip on the characteristics of a hydrodynamically lubricated sliding contact. The analysis results point out that with respect to the load support and the power loss of the bearing, the use of wall slip on smooth surface is the most excellent configuration compared to other patterns (i.e. slip-texturing, pure texturing and conventional patterns). It is also confirmed that the wedge effect due to the shaft eccentricity has a significant role in altering the lubricant behaviour. Thus, a particular care must be taken in choosing the pattern of lubricated sliding contact as well as the shaft eccentricity.

Parameter Identification of LuGre Friction Model: Experimental Set-up Design and Measurement

2015 ◽  
Author(s):  
Yun-Hsiang Sun ◽  
Tao Chen ◽  
Cyrus Shafai
Keyword(s):  
High Performance ◽  
Controller Design ◽  
Measurement Procedure ◽  
Friction Model ◽  
Operating Conditions ◽  
Dynamic Friction ◽  
Friction Modeling ◽  
Friction Behavior ◽  
Wide Range ◽  
Set Up

This work proposes a simple but general experimental approach including the rig design and measurement procedure to carry out a wide range of experiments required for identifying parameters for LuGre dynamic friction model. The design choice is based on accuracy of the estimated friction and flexibility in terms of changing contact conditions. The experimental results allow a complete LuGre model, which facilitates, but not limited to, other advanced friction modeling and high performance controller design if needed. In addition, several well-known dynamic friction features (varying break-away force, friction lag and presliding) are successfully demonstrated by our rig, which indicates the adequacy of our approach for capturing highly sophisticated and dynamic friction behavior over a wide range of operating conditions. The proposed set-up and the produced experimental data are believed to greatly facilitate the development of advanced friction compensation and modeling in friction affected mechanisms.

scholarly journals NUMERICAL MODEL OF A LOCAL CONTACT OF A POLYMER NANOCOMPOSITE AND ITS EXPERIMENTAL VALIDATION

2021 ◽  
Vol 19 (1) ◽  
pp. 079
Author(s):  
Andrey I. Dmitriev
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Friction Coefficient ◽  
Experimental Validation ◽  
Polymer Nanocomposite ◽  
Characteristic Size ◽  
Dry Sliding ◽  
Sliding Velocity ◽  
Low Friction ◽  
Local Contact

In the paper a model of a local contact of a polymer-based nanocomposite was developed within the method of a movable cellular automaton. The features of mechanical behavior of nanocomposite at the mesoscale level under dry sliding were studied with explicit account for the microprofile of the counterbody surface and the characteristic sizes of nanofiller. Factors that contribute to the conditions for the formation of a stable tribofilm of silica nanoparticles are analyzed. Two other parameters like sample geometry and the value of relative sliding velocity are also examined. It is shown that the thickness of tribofilm depends on stress conditions at the contact, and the friction coefficient decreases with increasing sliding velocity similar to one observed experimentally. To ensure the low friction properties of polymer nanocomposite, particles whose sizes are comparable with the characteristic size of the substrate microprofile are preferred. Results of numerical simulation are in good correlation with available experimental data.

A Novel Dynamic Friction Model Based on Asperity Creep

2008 ◽  
Author(s):  
Andreas Goedecke ◽  
Randolf Mock
Keyword(s):  
Friction Coefficient ◽  
Rough Surfaces ◽  
Fractal Model ◽  
Friction Model ◽  
Test Case ◽  
Dynamic Friction ◽  
Surface Asperity ◽  
Perfectly Plastic ◽  
Novel Approach ◽  
Asperity Model

We present a novel approach for the simulation of dynamic friction in engineering systems, based on a new surface asperity model including creep effects. Our novel friction model aims at understanding the link between the microscopic origins of friction dynamics and the response of the engineering-level friction induced vibrations. The approach is based on the assumption that the time- and velocity-dependent friction coefficient is mainly caused by creep growth of surface asperity contacts (microscopic contact patches between two rough surfaces) as proposed by Kragelskii, Rabinowicz, Scholz and others. At the heart of our approach is a new asperity model that includes creep effects. Based on the pioneering work of Etsion et al., we conducted extensive FEM simulations to analyze the creep behavior of an elastic-perfectly plastic hemisphere in contact with a rigid flat. The new asperity model is used as a building block for a fractal model for the contact between rough surfaces. The model yields the time- and velocity-dependent macroscopic friction coefficient. We demonstrate the practical applicability of the new dynamic friction model in a simple block-on-conveyor test case to analyze friction induced vibrations.

Sign in / Sign up

Export Citation Format

Share Document