Surface Topography and Friction Dynamics in Brake Systems Described by a Cellular Automaton

2005 ◽  
Author(s):  
M. Mueller ◽  
G. P. Ostermeyer
Keyword(s):  
Friction Coefficient ◽  
Kinetic Energy ◽  
Cellular Automata ◽  
Relative Velocity ◽  
Friction And Wear ◽  
Normal Load ◽  
Friction Behavior ◽  
Plastic Deformations ◽  
Parameter Dependent ◽  
Friction Dynamics

For the description of a friction event it is necessary to understand the friction coefficient μ as a process-parameter dependent not only on the surface-structure but also for instance on the relative velocity, normal load, temperature and the event itself. In brake systems, for example, growing and destroying processes of hard thin patches determine the friction power and the transfer of kinetic energy into heat and plastic deformations, such as wear. So the interaction of friction and wear is given by an equilibrium of flow of different processes resulting in growing effects or lowering effects on the friction coefficient itself [2]–[4]. The aim of this paper is to show the detailed interaction of this topographical dynamics and the friction behavior with the Method of Cellular Automata.

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.

The Effect of Sliding Speed on Friction and Wear of RBD Palm Olein

2013 ◽  
Vol 315 ◽  
pp. 951-955 ◽  
Author(s):  
Samion Syahrullail ◽  
Jazair Yahya Wira ◽  
W.B. Wan Nik ◽  
Chiong Ing Tiong
Keyword(s):  
Friction Coefficient ◽  
Friction And Wear ◽  
Palm Olein ◽  
Normal Load ◽  
Mineral Oil ◽  
Low Friction ◽  
Sliding Speed ◽  
Rbd Palm Olein

In this paper, the effect of sliding speed on the anti-friction of RBD palm olein was investigated using four-ball tribotester. The speeds were varied from 800 to 1400 rpm. The normal load was set to 40 kg and the test oil was heated up to 75 °C before the experiments. The result showed that palm olein has low friction coefficient compared to additive-free paraffinic mineral oil.

What Causes Low Friction? — What Causes High Friction?

2005 ◽  
Author(s):  
Y. Elaine Zhu ◽  
Steve Granick
Keyword(s):  
Friction Coefficient ◽  
Recent Work ◽  
Frictional Force ◽  
Friction And Wear ◽  
Normal Load ◽  
Low Friction ◽  
Strategic Design ◽  
Modern Methods ◽  
Design Requirements ◽  
The Many

The design of tribological interfaces is often motivated by a quest to minimize friction and wear. Among the many strategic design principles that have been developed to this end, the simple idea of decoupling frictional force from normal load is especially attractive. Recent work from this laboratory demonstrates that under certain conditions, it is possible to reduce this coupling significantly with the result that the friction coefficient appears to be very low. However, the materials design requirements to achieve this end are rather stringent. Furthermore, modern methods enable one under some conditions to measure directly the structure and motions of lubricants during tribological sliding.

Friction and wear behavior of hydrogenated diamond-like carbon coating against titanium alloys under large normal load and variable velocity

2017 ◽  
Vol 69 (2) ◽  
pp. 199-207 ◽  
Author(s):  
Jun Liu ◽  
Zhinan Zhang ◽  
Zhe Ji ◽  
Youbai Xie
Keyword(s):  
Friction Coefficient ◽  
Service Life ◽  
Carbon Coating ◽  
Friction And Wear ◽  
Wear Behavior ◽  
Normal Load ◽  
Diamond Like Carbon ◽  
Content Type ◽  
Friction And Wear Behavior ◽  
Dlc Coating

Purpose This paper aims to investigate the effects of reciprocating frequency, large normal load on friction and wear behavior of hydrogenated diamond-like carbon (H-DLC) coating against Ti-6Al-4V ball under dry and lubricated conditions. Design/methodology/approach The friction and wear mechanisms are analyzed by scanning electron microscope, energy dispersive spectroscopy and Raman spectroscopy. Findings The results show that as reciprocating frequency increases under lubricated conditions, the friction coefficient decreases first and then increases. When the reciprocating frequency is 2.54 Hz, the value of friction coefficient reaches the minimum. The friction reduction is because of the transformation from sp3 to sp2, the formation of transfer layer on Ti-6Al-4V ball and the reduction in viscous friction, whereas the increase of friction coefficient is related to wear. In dry conditions, the friction coefficient is between 0.06 and 0.1. And, the service life of H-DLC coating decreases with the increase in reciprocating frequency and normal load. Research limitations/implications It is confirmed that adding the lubricant could prolong the service life of H-DLC coating and reduce friction and wear efficiently. And, the wear mechanisms under dry and lubricated conditions encompass abrasive wear and adhesive wear. Originality/value The results are helpful for application of diamond-like carbon coating.

The Mechanical Properties and Friction and Wear Behavior of C/C-SIC

2010 ◽  
Author(s):  
Gao Wen ◽  
Chongsheng Long ◽  
Tang Rui ◽  
Jiping Wang
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Friction And Wear ◽  
Wear Behavior ◽  
Normal Load ◽  
Carbon Matrix ◽  
Specific Wear Rate ◽  
Sliding Speed ◽  
Wear Rates ◽  
Sic Composites

Carbon fiber reinforced carbon-silicon carbide composites (C/C-SiC) were prepared by chemical volume infiltration (CVI) method and reaction melt infiltration (RMI) technique of silicon liquid to carbon reinforce carbon matrix composites. The friction and wear behaviors of C/C-SiC composites at various loads and sliding speeds were investigated by MRH-3 block-on-ring tribometer at room temperature under water lubricating conditions. Furthermore, the morphologies, phase of the worn surface and the debris were observed, examined and analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX) respectively. Experimental results showed that the C/C-SiC composites had a better wear resistence, and the friction coefficient under water lubricated conditions is about 0.02–0.06. The influence of sliding speed on the friction coefficients and the specific wear rate of C/C-SiC is more obvious than that of normal load when the load is less than 200N (inclueded200N). The friction coefficient and the specific wear rate of C/C-SiC decreased as the sliding velocity increased. At the sliding speed higher than 2m/s, the friction coefficient is less than 0.02. The specific wear rates is at a low level about (2×10−7mm3/Nm–5×10−8mm3/Nm).

Friction and wear tester

2020 ◽  
Vol 86 (8) ◽  
pp. 66-71
Author(s):  
V. E. Red’kin ◽  
Yu. S. Tkachenko ◽  
P. O. Sukhodaev ◽  
A. I. Lyamkin
Keyword(s):  
Friction Coefficient ◽  
Friction And Wear ◽  
Metal Cutting ◽  
Normal Load ◽  
Graphite Powder ◽  
Friction Torque ◽  
Tribological Characteristics ◽  
Friction Machine ◽  
Industrial Oil ◽  
Flat Spiral

A compact and simple in design device (friction machine) for testing materials for friction and wear is developed. The device is intended for determination of the wear resistance and friction coefficient of structural, frictional and antifriction materials, as well as the tribological characteristics of lubricants. The measurement system of the device includes spring helical and flat spiral elastic elements, combined in one node and designed to measure the normal force and friction torque, respectively. Metal-cutting machines can be used as an external drive of the device. The friction machine was tested when measuring the wear rate and the value of the friction coefficient of the samples of cast iron SCh20, brass L63, technical aluminum A7, as well as modified aluminum A7 with improved mechanical characteristics. The materials were tested in tandem with a counter-sample made of hardened steel 95Kh18 according to the ball-ring scheme in dry friction mode and in boundary lubrication mode using I-20A industrial oil at a normal load of 50 N and a linear velocity in the contact zone of 0.5 m/sec. The wear degree was estimated by the weight loss. The obtained results are characterized by the sufficient accuracy and reproducibility. A severe wear of brass is observed at a given testing load. Tests of the aluminum samples modified with ultrafine diamond-graphite powder UDP-AG obtained from explosives showed an increase in the tribological characteristics by 10 – 18%.

Lessons Learned From 25 Years of Friction Modeling

2003 ◽  
Author(s):  
Andres Soom
Keyword(s):  
Friction Coefficient ◽  
Scale Effects ◽  
Normal Load ◽  
Constitutive Relations ◽  
Lessons Learned ◽  
Contact Forces ◽  
Friction Modeling ◽  
Friction Behavior ◽  
Primary Means ◽  
The Coefficient Of Friction

We have long known that tangential contact forces and the friction coefficient at a sliding contact arises not due to some “law” but as a result of contact geometric and material properties in combination with physical processes that are not always accessible to direct experimental verification. While tribologists have occasionally sought alternatives to the coefficient of friction as the primary means to quantify tangential forces at sliding contacts, its convenience, simplicity, long history and lack of viable alternatives assure that it will be remain in use for some time to come. Sometimes the coefficient can remain constant with normal load over orders or magnitude. One can be led to believe that the coefficient is a property of the interface or there is a “law” at work. At other times, the coefficient, usually measured, is said to vary with time, sliding distance or some other variable with no explanation as to why the variation occurs. In the present paper we discuss aspects of friction behavior and modeling, focusing on mechanics and the nature of the friction coefficient. The point of departure is a case where the adhesion theory of friction can be used to understand the mechanics of friction. One can then consider a number of situations and concepts that arise as variations of this case including average versus instantaneous friction; cases when Amontons-Coulomb relations do or don’t apply; static versus dynamic friction; scale effects at rough surfaces; limits of applicability of the friction coefficient; friction measurements, thermal and velocity effects; and local versus global friction and constitutive relations.

A Comparative Study on the Tribological Behavior of SAE-AISI 1055 Steel and Brass (CuZn39Pb2) a Pin on Disc Type of Contact

2019 ◽  
Vol 397 ◽  
pp. 147-160
Author(s):  
Bougoffa Mohammed Seyf Eddine ◽  
Mebrouki Noura
Keyword(s):  
Friction Coefficient ◽  
Friction And Wear ◽  
Test Bench ◽  
Tribological Behavior ◽  
Wear Behavior ◽  
Normal Load ◽  
Wear Loss ◽  
Initial Surface ◽  
Sliding Speed ◽  
Friction And Wear Behavior

The paper assesses and compares the friction and wear behavior of SAE-AISI 1055 steel and brass (CuZn39Pb2) under dry sliding condition. The tribological behavior was investigated and compared by conducting two different experiments, the first experiment conducted on a CSM tribometer, and the second experiment was carried out on a test bench in horizontal lathe machine where device holder pin is fabricated and mounted on a test bench and a rotating disc, varying the normal load exert on the disc by the pin and the rotation speed of the disc. These tests consisted of measuring friction coefficient and wear loss of samples. Experiments are carried out in normal load 5-10 N, sliding speed 0.24-0.35 and 0.48 m/s. Variations of coefficient of friction during sliding at different initial surface roughness, normal load and sliding speed are investigated. Results show that the two alloys had different friction and wear behavior, for steel friction coefficient increase slowly with the increase of normal load and sliding speed. For brass friction coefficient decreases with the increase of normal load and sliding speed. On the other hand, it is also found that wear loss increase with sliding distance. Microscopic of worn surfaces for each alloy were carried out and compared.

Experimental Investigation of Friction Dynamics Associated With Normal Load

1995 ◽  
Author(s):  
Pierre E. Dupont ◽  
Prakash S. Kasturi
Keyword(s):  
Normal Force ◽  
Normal Load ◽  
System Stability ◽  
Complete Understanding ◽  
Order Model ◽  
Friction Behavior ◽  
Ongoing Research ◽  
Stability And Control ◽  
And Control ◽  
Friction Dynamics

Abstract In the last five years, it has become clear that for a broad range of systems which exhibit significant friction, the dynamics of the friction itself must be included to reach a complete understanding of system stability and control issues. Dynamics associated with variations in velocity have received most of the attention while those associated with variations in normal load have been largely ignored. This paper presents results of ongoing research in the experimental identification of friction dynamics due to variations in both normal load and velocity for a line contact in boundary lubrication. Tests were conducted with inputs consisting of step changes in velocity and normal force. Our analyses indicate that a first or second order model is necessary to represent dynamic friction behavior associated with these inputs.

Effect of Tribochemical Interactions on Friction and Wear of Highly Hydrogenated DLC Films

2007 ◽  
Author(s):  
O. L. Eryilmaz ◽  
A. Erdemir
Keyword(s):  
Friction Coefficient ◽  
Photoelectron Spectroscopy ◽  
Friction And Wear ◽  
Friction Behavior ◽  
Test Environment ◽  
Sliding Surfaces ◽  
Tof Sims ◽  
Diamondlike Carbon ◽  
Major Chemical ◽  
Secondary Ion

In this paper, we attempted to elucidate the nature and extent of tribochemical interactions between sliding surfaces of highly-hydrogenated diamondlike carbon (DLC) films (containing about 40 at.% hydrogen) and correlated these findings with their friction and wear behaviors in dry and humid nitrogen environments. For the tribochemical studies, we used a time-of-flight secondary ion mass spectrometer (ToF-SIMS) in 2- and 3-D imaging modes, while for tribological tests, we used a ball-on-disk machine that was operated under a 5 N load and at sliding velocities of 0.2 to 0.3 m/s. In dry nitrogen, the DLC films provided a friction coefficient of ≈ 0.007, but in humid nitrogen, the friction coefficient 3 to 4 times higher. 3-D surface profilometry and optical microscopy did not reveal much wear on sliding ball and disk surfaces after the tests regardless of the test environment, but the 2- and 3-D ToF-SIMS images of the same surfaces revealed very rich tribochemistry for films tested in humid nitrogen but not much chemistry for those films tested in dry nitrogen. Complementary x-ray photoelectron spectroscopy of these sliding surfaces showed similar results further confirming extensive tribo-oxidation (in the forms of both C-O and C=O) of DLC surfaces tested in humid nitrogen but no major chemical changes in DLC films tested in dry nitrogen. Based on the results of surface analytical and tribological studies, we concluded that superlow friction behavior of highly hydrogenated DLC films was perhaps due to the hydrogen termination of their surface carbon atoms, while the much higher friction coefficients observed in humid nitrogen was primarily due to tribo-oxidation and/or oxygen termination of these surfaces.

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