SOME COMMENTS ON THE INTERPRETATION OF THE TRIBOLOGICAL WEAR COEFFICIENT

Tribologia ◽  
2021 ◽  
Vol 296 (2) ◽  
pp. 45-56
Author(s):  
Jan Sadowski
Keyword(s):  
Energy Dissipation ◽  
Thermodynamic Analysis ◽  
Sliding Friction ◽  
Original Model ◽  
Mechanical Work ◽  
Linear Wear ◽  
Volumetric Wear ◽  
Wear Coefficient ◽  
Full Conversion

An original model of tribological wear is presented, an alternative to the commonly used J.F. Archard’s model. The impossibility is established of a full conversion of mechanical work into the heat of dissipation and thereby of avoiding wear in the sliding friction of solids. The assumption is consequently questioned that only some contacts of surface asperities are subject to temporary wear. Material wastage is assumed to occur at each contact of asperities. The volume of worn material is dependent on the volumetric wear coefficient of the “energy dissipation zone” in friction. The dimensions of the zone are determined in both the elements in friction. Linear wear intensities and volumetric wear are described in analytical terms. The thermodynamic analysis of the tribological process indicates some limitations to these intensities. Energetic efficiencies of solid wear and heating as a result of friction are defined. Some new interpretations of the wear coefficient are proposed.

Precision of wear measurement using the shadowgraph technique

2007 ◽  
Vol 221 (8) ◽  
pp. 899-902 ◽  
Author(s):  
J L Cunningham ◽  
I Bisbinas ◽  
R Greenwood ◽  
I D Learmonth
Keyword(s):  
Coefficient Of Variation ◽  
Internal Surface ◽  
Measurement Precision ◽  
Linear Wear ◽  
Volumetric Wear ◽  
Wear Coefficient ◽  
Inexpensive Method ◽  
Wear Measurement

The shadowgraph technique is a relatively easy-to-use and inexpensive method of wear measurement from explanted acetabular cups. In this technique, from a mould of the internal surface of the cup, measurements of linear wear and wear angle can be obtained, from which volumetric wear can be calculated. In this study the measurement precision of this technique was assessed and the influence of different observers and multiple moulds was also determined. It was found that linear wear (coefficient of variation (CV) = 1.49 per cent) can be more precisely determined than wear angle (CV = 8.18 per cent) and that both the observer and the mould can significantly influence the results obtained, although the influence of the mould is considerably less than that of the observer.

scholarly journals Optimal Energy Dissipation in Sliding Friction Simulations

2012 ◽  
Vol 48 (1) ◽  
pp. 41-49 ◽  
Author(s):  
A. Benassi ◽  
A. Vanossi ◽  
G. E. Santoro ◽  
E. Tosatti
Keyword(s):  
Energy Dissipation ◽  
Sliding Friction ◽  
Optimal Energy

scholarly journals Seismic Behavior of Steel Column Base with Slip-Friction Connections

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3986
Author(s):  
Chengyu Li ◽  
Qi Liu ◽  
Gongwen Li
Keyword(s):  
Free Energy ◽  
Energy Dissipation ◽  
Axial Compression ◽  
Sliding Friction ◽  
Future Research ◽  
Hysteretic Performance ◽  
Good Energy ◽  
Base Connections ◽  
The Cost ◽  
Column Base

Traditional rigid column base connections are damaged to different degrees after an earthquake and the damage is generally nonrecoverable. Thus, the cost of repairing or dismantling is quite high. A new type of slip-friction column base connection is proposed in this paper, which aims to replace the yielding energy dissipation of the traditional column base connection by the sliding friction energy dissipation between the arc endplates, thus achieving the design objective of damage-free energy dissipation. Finite element simulation was conducted to study the hysteretic performance of the proposed connections considering different axial compression ratios. The research indicates that both kinds of the proposed connections show good energy dissipation behavior and the increase of axial compression force can increase the energy dissipation ability. It also shows that the two kinds of connections can achieve the objective of damage-free energy dissipation. For the proposed connection, future research is still needed such as corresponding tests in the laboratory, the effect of the connection on the whole structure, and the re-centering systems for the connections.

scholarly journals Single-asperity sliding friction across the superconducting phase transition

2020 ◽  
Vol 6 (12) ◽  
pp. eaay0165 ◽  
Author(s):  
Wen Wang ◽  
Dirk Dietzel ◽  
André Schirmeisen
Keyword(s):  
Energy Dissipation ◽  
Sliding Friction ◽  
Point Contact ◽  
Electronic Energy ◽  
Contact Friction ◽  
Electron Systems ◽  
Single Asperity ◽  
Large Peak ◽  
Friction Models ◽  
Current Point

In sliding friction, different energy dissipation channels have been proposed, including phonon and electron systems, plastic deformation, and crack formation. However, how energy is coupled into these channels is debated, and especially, the relevance of electronic dissipation remains elusive. Here, we present friction experiments of a single-asperity sliding on a high-Tc superconductor from 40 to 300 kelvin. Overall, friction decreases with temperature as generally expected for nanoscale energy dissipation. However, we also find a large peak around Tc. We model these results by a superposition of phononic and electronic friction, where the electronic energy dissipation vanishes below Tc. In particular, we find that the electronic friction constitutes a constant offset above Tc, which vanishes below Tc with a power law in agreement with Bardeen-Cooper-Schrieffer theory. While current point contact friction models usually neglect such friction contributions, our study shows that electronic and phononic friction contributions can be of equal size.

Energy dissipation and the contact-line region of a spreading bridge

2012 ◽  
Vol 703 ◽  
pp. 111-141 ◽  
Author(s):  
H. B. van Lengerich ◽  
P. H. Steen
Keyword(s):  
Energy Dissipation ◽  
Flow Field ◽  
Contact Line ◽  
Sliding Friction ◽  
Slip Length ◽  
Cox Model ◽  
Hydrophobic Surface ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Line Region

AbstractA drop on a circular support spontaneously spreads upon contact with a substrate. The motion is driven by a loss of surface energy. The loss of recoverable energy can be expressed alternatively as work done at the liquid–gas interface or dissipation through viscosity and sliding friction. In this paper we require consistency with the energy lost by dissipation in order to infer details of the contact-line region through simulations. Simulations with the boundary integral method are used to compute the flow field of a corresponding experiment where polydimethylsiloxane spreads on a relatively hydrophobic surface. The flow field is used to calculate the energy dissipation, from which slip lengths for local slip and Navier slip boundary conditions are found. Velocities, shear rates and pressures along the interface as well as interface shapes in the microscopic region of the contact line are also reported. Angles, slip length and viscous bending length scale allow a test of the Voinov–Hocking–Cox model without free parameters.

Energy quadratization Runge-Kutta method for the modified phase field crystal equation

2021 ◽  
Author(s):  
Jaemin Shin ◽  
Hyun Geun Lee ◽  
June-Yub Lee
Keyword(s):  
Energy Dissipation ◽  
Phase Field ◽  
Mass Conservation ◽  
Energy Functional ◽  
Original Model ◽  
Auxiliary Variables ◽  
Runge Kutta Method ◽  
Runge Kutta ◽  
Phase Field Crystal

Abstract In this paper, we propose high order and unconditionally energy stable methods for a modified phase field crystal equation by applying the strategy of the energy quadratization Runge–Kutta methods. We transform the original model into an equivalent system with auxiliary variables and quadratic free energy. The modified system preserves the laws of mass conservation and energy dissipation with the associated energy functional. We present rigorous proofs of the mass conservation and energy dissipation properties of the proposed numerical methods and present numerical experiments conducted to demonstrate their accuracy and energy stability. Finally, we compare long-term simulations using an indicator function to characterize the pattern formation.

Prediction of Built-Up Layer and Built-Up Edge Formation in Dry Cutting of SUS304 Stainless Steel

2019 ◽  
Vol 13 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Xiaoqi Song ◽  
◽  
Yukio Takahashi ◽  
Tohru Ihara
Keyword(s):  
Stainless Steel ◽  
Energy Dissipation ◽  
Thermodynamic Analysis ◽  
Formation Mechanisms ◽  
Dry Cutting ◽  
Contact Conditions ◽  
Sus304 Stainless Steel ◽  
Proposed Model ◽  
Formation Conditions ◽  
Dissipation Processes

This paper presents a thermodynamic model for studying the energy dissipation processes such as friction, wear, and the adhesion phenomenon in order to predict the built-up layer (BUL) and built-up edge (BUE) formation conditions in dry cutting of SUS304 stainless steel. The model is composed of three parts: the extended representative contact model (RCM) at the tool and chip interface, the thermodynamic analysis within the RCM, and the growth model. At a typical region, the RCM is characterized by three material elements and two boundary elements, which support the contact conditions between two material elements. Thermodynamic analysis within the RCM reveals that apart from friction and wear, the BUL/BUE formation is also an irreversible energy dissipation process. The BUL/BUE can be called as a “dissipative structure substance,” which can reduce tool wear. Meanwhile, the RCM is an open system because it allows for the transfer of energy and matter with its surrounding. Energy exchange and mass exchange exert significant influences on the BUL/BUE growth. It is verified that the BUL/BUE growth depends significantly on four energy dissipation processes: workpiece fracture, friction, workpiece accumulation, and reduction of adhesion. In addition, the proposed model is verified by comparing simulations with the corresponding experimental results of dry cutting of SUS304 stainless steel. It is verified that the BUL/BUE develops its characteristics with cutting time and that the proposed model can accurately predict the BUL/BUE formation conditions. These results have provided a deeper understanding of the BUL/BUE formation mechanisms.

scholarly journals Effect of Polypropylene Modification by Impregnation with Oil on Its Wear and Friction Coefficient at Variable Load and Various Friction Rates

2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Paweł Sędłak ◽  
Beata Białobrzeska ◽  
Tomasz Stawicki ◽  
Piotr Kostencki
Keyword(s):  
Friction Coefficient ◽  
Sliding Friction ◽  
Wear Test ◽  
Friction Torque ◽  
Engine Oil ◽  
Wear Testing ◽  
Wear Behaviour ◽  
Linear Wear ◽  
Variable Load ◽  
Fatigue Wear

Laboratorial two-body wear testing was carried out in order to assess effects of polypropylene modification by impregnating it with oils on friction coefficient and wear in comparison to those parameters of unmodified polypropylene, Teflon, and polyamide during operation under conditions of sliding friction without lubrication. Wear behaviour of the tested specimens was investigated using ASTM G77-98 standard wear test equipment. Recording program made it possible to visualise and record the following parameters: rotational speed and load, linear wear, friction coefficient, temperature of the specimen, and ambient temperature. In addition, wear mechanisms of the analysed materials were determined with use of scanning electron microscopy. In the case of the remaining tested polymers, the most important mechanism of wear was adhesion (PP, PTFE, PA 6.6, and PA MoS2), microcutting (PTFE, PA 6.6, and PA MoS2), fatigue wear (PTFE), forming “roll-shaped particles” combined with plastic deformation (PA 6.6 and PA MoS2), and thermal wear (PP). Impregnation of polypropylene with engine oil, gear oil, or RME results in significant reduction of friction coefficient and thus of friction torque, in relation to not only unmodified polypropylene but also the examined polyamide and Teflon.

scholarly journals Atomic-scale sliding friction on a contaminated surface

Nanoscale ◽  
2018 ◽  
Vol 10 (14) ◽  
pp. 6375-6381 ◽  
Author(s):  
Wengen Ouyang ◽  
Astrid S. de Wijn ◽  
Michael Urbakh
Keyword(s):  
Energy Dissipation ◽  
Friction Force ◽  
Surface Coverage ◽  
Sliding Friction ◽  
Normal Load ◽  
Atomic Scale ◽  
Nonlinear Variation ◽  
Strongly Nonlinear

The interplay between different channels of energy dissipation may lead to non-monotonic dependence of the friction force on the adsorbate surface coverage and to strongly nonlinear variation of friction with normal load.

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