Frictional Properties of a Surface Covered With Soft Metal Film (Interference Effect of Soft Metal Film Deformation Between Two Protuberances)

1985 ◽  
Vol 107 (4) ◽  
pp. 444-451 ◽  
Author(s):  
Shinobu Kato ◽  
Etsuo Marui ◽  
Kiyoo Tachi
Keyword(s):  
Plastic Flow ◽  
Interference Effect ◽  
Metal Film ◽  
Flow Line ◽  
Contact Pressure Distribution ◽  
Frictional Properties ◽  
Frictional Characteristic ◽  
The Coefficient Of Friction ◽  
Soft Metal ◽  
Flow Deformation

The frictional characteristic is examined with reference to a model considering the interference effect of plastic flow (deformation) in soft metal film, when a two-protuberance indentor is slid on a surface covered by electroplated soft metal film. The result is compared with that of a single-protuberance indentor. The coefficient of friction in a two-protuberance indentor, where the interference effect exists, is lower than in a single-protuberance indentor, where the interference effect does not. This fact can well be explained with the configuration of plastic flow line on protuberances described by deforming soft metal film, and the corresponding contact pressure distribution between protuberances and a surface.

Frictional Properties of a Surface Covered With a Soft Metal Film—Part 1: Experiments on Friction Between a Single Protuberance and a Surface

1981 ◽  
Vol 103 (2) ◽  
pp. 236-242 ◽  
Author(s):  
S. Kato ◽  
K. Yamaguchi ◽  
E. Marui ◽  
K. Tachi
Keyword(s):  
Coefficient Of Friction ◽  
Deformation Mechanism ◽  
Metal Film ◽  
Surface Film ◽  
Thin Metal Film ◽  
Film Properties ◽  
Empirical Expression ◽  
Frictional Properties ◽  
The Coefficient Of Friction ◽  
Soft Metal

Frictional properties in the contact between a hard protuberance and a metal surface covered by a soft thin metal film are examined experimentally. The protuberance used in the experiment is a hard steel ball which simulates asperities on many engineering surfaces. The load dependency of the coefficient of friction and the effects of thickness and hardness of the film on the friction are clarified. The simple empirical expression of friction, which represents the effect of the film properties, is presented, considering the deformation mechanism of the surface film.

Frictional Properties of a Surface Covered With a Soft Metal Film—Part 2: Analysis of Friction Between a Single Protuberance and a Surface

1982 ◽  
Vol 104 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Shinobu Kato ◽  
Katsumi Yamaguchi ◽  
Etsuo Marui ◽  
Kiyoo Tachi
Keyword(s):  
Pressure Distribution ◽  
Coefficient Of Friction ◽  
Metal Film ◽  
Surface Film ◽  
Analytical Investigation ◽  
Friction Characteristic ◽  
Frictional Properties ◽  
The Coefficient Of Friction ◽  
Soft Metal ◽  
Side Flow

Analytical investigation of the evaluation of the coefficient of friction is made to clarify the mechanism of the load dependency of friction, which was obtained in Part 1 of this research, and also to ascertain the effects of the surface film on the friction characteristic. The plastic flow of the soft metal film between a protuberance and the subsurface is presumed, and the pressure distribution originating from the side flow is calculated on the basis of the plasticity theory. The effects of the coefficient of friction of the load, the thickness and hardness of the film, and the radius of the protuberance, are examined. As a result, it is clarified that the load dependency of friction arises from the extremely high pressure distribution generated in the film.

Frictional Properties of a Surface Covered With Soft Metal Surface Film (Surface Topography and Frictional Properties)

1987 ◽  
Vol 109 (3) ◽  
pp. 545-551 ◽  
Author(s):  
Shinobu Kato ◽  
Etsuo Marui ◽  
Kiyoo Tachi
Keyword(s):  
Surface Topography ◽  
Metal Surface ◽  
Metal Film ◽  
Surface Film ◽  
Frictional Coefficient ◽  
Film Surface ◽  
Small Radius ◽  
Radius Of Curvature ◽  
Frictional Properties ◽  
Soft Metal

The friction between a real engineering surface composed of many micro-asperities and a surface covered with soft metal film is discussed. First, the frictional coefficient shows a remarkable load dependency, when a hard single protuberance with a small radius of curvature is slid on a soft metal surface. This load dependence originates from the ploughing effect induced by the cooperation of contact pressure and shearing resistance of the soft metal film deforming on the protuberance surface. Based on this result, the effect of the real engineering surface topography on the frictional properties is studied.

scholarly journals Flow deformation characteristics of African blackwood, Dalbergia melanoxylon

2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Kazushi Nakai ◽  
Soichi Tanaka ◽  
Kozo Kanayama ◽  
Tsuyoshi Yoshimura
Keyword(s):  
Plastic Flow ◽  
Local Community ◽  
Tangential Direction ◽  
Musical Instruments ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Flow Forming ◽  
Community Forests ◽  
Flow Deformation ◽  
Dalbergia Melanoxylon

Abstract African blackwood (ABW: Dalbergia melanoxylon) is a valuable tree in Tanzanian local community forests, and heartwood has been mainly utilized as an irreplaceable material in musical instruments, e.g., clarinet, oboe and piccolo. Since its use is generally for the production of musical instruments only, most of the harvested volume is wasted due to defects that would affect the quality of final products. Wood flow forming can transform bulk woods into materials in temperature/pressure-controlled mold via plastic flow deformation. The main object of this study was to evaluate the deformation characteristics of ABW heartwood in developing the potential of wasted ABW parts in terms of the effective material use. The deformation characteristics of heartwood were examined by free compression tests. Specimens were compressed along the radial direction at 120 °C, and air-dried heartwood was dramatically deformed in the tangential direction. The plastic flow deformation of ABW was amplified by the presence of both extractives and moisture. In particular, the ethanol/benzene (1:2, v/v) soluble extractives in heartwood may have contributed to flow deformation. The results of the dynamic mechanical analysis showed that the air-dried heartwood exhibited softening in a temperature range over 50 °C. The ethanol/benzene-soluble extractives contributed to the softening behavior. The clarified deformation characteristics of ABW can contribute to more efficient material use of local forests.

FRICTIONAL PROPERTIES OF PALM KERNEL ACTIVATED CARBON-EPOXY COMPOSITE UNDER VARIOUS NORMAL LOADS

2015 ◽  
Vol 76 (10) ◽  
Author(s):  
Khai Wei Chua ◽  
Mohd Fadzli Bin Abdollah ◽  
Noor Ayuma Mat Tahir ◽  
Hilmi Amiruddin
Keyword(s):  
Activated Carbon ◽  
Room Temperature ◽  
Epoxy Composite ◽  
Normal Load ◽  
Palm Kernel ◽  
Molding Method ◽  
Frictional Properties ◽  
Pin On Disc ◽  
The Coefficient Of Friction ◽  
Sliding Test

This study investigates the effect of normal load on the frictional properties of palm kernel activated carbon-epoxy (PKAC-E) composite. The PKAC-E composite specimen was fabricated by hot compression molding method. The dry sliding test was performed by using a pin-on-disc tribometer at various normal loads, range from 5 – 100N. The sliding speed and distance were constant. All tests were performed at room temperature. It was found that the coefficient of friction decreases with normal load, though at 60N, friction coefficient increases slightly and remains almost invariant at about 0.04 with normal load. The main conclusion of this study is that PKAC-E composite has a potential for tribological material application but only limited at low normal load under unlubricated conditions.

scholarly journals Towards programmable friction: control of lubrication with ionic liquid mixtures by automated electrical regulation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Felix Gatti ◽  
Tobias Amann ◽  
Andreas Kailer ◽  
Norman Baltes ◽  
Jürgen Rühe ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Molecular Orientation ◽  
Liquid Mixtures ◽  
Mechanical Stimulus ◽  
Mass Ratio ◽  
Surface Charges ◽  
Friction Control ◽  
Frictional Properties ◽  
The Coefficient Of Friction ◽  
Electric Impulse

Abstract For mechanical systems in relative motion it would be fascinating if a non-mechanical stimulus could be used to directly control friction conditions. Therefore, different combinations of lubricants and external triggers for tribological influence have already been investigated. We show that when two metallic friction partners are lubricated with ionic liquid mixtures (ILM), consisting of long-chain cation and two different high charge/mass ratio anion containing ILs, the application of an electric impulse induces a permanent change of the frictional response. Such mixtures are able to alter the coefficient of friction (COF) to a greater extent, more accurately and faster than the respective single-component ILs. This change in the frictional properties is presumably due to changes in the externally induced electrical polarization at the surface, which influences the molecular adsorption, the exchange of adsorbed ions and their molecular orientation. The correlation between surface charges and friction can be used to control friction. This is achieved by implementing an electric tribo-controller which can adjust preset friction values over time. Programming friction in this way is a first step towards tribosystems that automatically adapt to changing conditions.

The Influence of Surface Roughness on the Mechanism of Friction

1970 ◽  
Vol 92 (2) ◽  
pp. 264-272 ◽  
Author(s):  
T. Tsukizoe ◽  
T. Hisakado
Keyword(s):  
Surface Roughness ◽  
Metal Surface ◽  
Coefficient Of Friction ◽  
Dry Friction ◽  
Metal Surfaces ◽  
Roughness Effects ◽  
Real Area Of Contact ◽  
The Coefficient Of Friction ◽  
Tangential Forces ◽  
Soft Metal

A study was made of surface roughness effects on dry friction between two metals, assuming that the asperities are cones of the slopes which depend on the surface roughness. The theoretical explanations were offered for coefficients of friction of the hard cones and spheres ploughing along the soft metal surface. A comparison of calculated values based on these with experimental data shows good agreement. Moreover, theoretical discussion was carried out of surface roughness effects on dry friction between two metal surfaces on the basis of the analyses of the frictional mechanism for a hard slider on the metal surface. The theoretical estimation of the coefficient of friction between two metal surfaces can be carried out by using the relations between the surface roughness and the slopes of the asperities, and the coefficient of friction due to the adhesion at the interface. The experiments also showed that when two metal surfaces are first loaded normally and then subjected to gradually increasing tangential forces, real area of contact between them increases and the maximum tangential microslip of them increases with the increase of the surface roughness.

Hot judder behavior in multidisc clutches

2016 ◽  
Vol 231 (1) ◽  
pp. 136-146 ◽  
Author(s):  
Biao Ma ◽  
Likun Yang ◽  
Heyan Li ◽  
Nan Lan
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Degrees Of Freedom ◽  
Frictional Heat ◽  
Contact Pressure Distribution ◽  
Element Analysis ◽  
Pressure Distributions ◽  
Engagement Process ◽  
The Coefficient Of Friction ◽  
Interface Contact

This paper presents an investigation of the hot judder phenomenon of multidisc clutches, which takes place during the engagement process. Depending on the results of finite element analysis, a pressure distribution function is defined and a contact pressure equation is established to demonstrate the non-uniformity of the contact pressure distribution on the friction interfaces due to frictional heat. The relationship between the coefficient of friction and the temperature is analyzed. A 4 degrees of freedom power-train model is developed to evaluate the clutch judder behavior. The paper indicates that the clutch judder is influenced by the non-uniformity of the interface contact pressure distribution, which is excited by frictionally induced thermal load. The non-uniform contact pressure distributions along the radial direction have a slight influence on the clutch judder, while the uneven contact pressure distributions along the circumference contribute to the judder substantially. Furthermore, the results in this work can be used to study the operation instability and the thermal failure of clutches.

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