scholarly journals Self-Organization and Friction During Sliding

2012 ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas ◽  
Michael R. Lovell
Keyword(s):  
The Self ◽  
Steel Plates ◽  
Self Organization ◽  
Layer Formation ◽  
Transfer Layer ◽  
Surface Textures ◽  
Self Organized ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Number Of Cycles

In self-organized sliding processes, the surfaces align to each other during sliding. This alignment leads to a more ordered contact state and significantly influences the frictional behavior. To understand the self-organization sliding processes, experiments were conducted on a pin-on-plate reciprocating sliding tester for various numbers of cycles. In the experiments, soft magnesium pins were slid against hard steel plates of various surface textures (undirectional, 8-ground, and random). Experimental results showed that the transfer layer formation on the steel plates increased with increasing number of cycles for all surfaces textures under both dry and lubricated conditions. The friction also increased with the number of cycles under dry conditions for all of the textures studied. During lubricated conditions, the friction decreased for unidirectional and 8-ground surfaces and increased for random surfaces with the number of cycles. Furthermore, the friction and transfer layer formation depend on the surface textures under both dry and lubricated conditions during the first few sliding cycles. Later on, it is less dependent of surface textures. The variation in the coefficient of friction under both dry and lubrication conditions were attributed to the self-organization process that occurred during repeated sliding.

Response of Metals and Polymers During Sliding: Role of Surface Texture

2010 ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas ◽  
Michael R. Lovell
Keyword(s):  
Surface Texture ◽  
Hardened Steel ◽  
Steel Plates ◽  
Layer Formation ◽  
Transfer Layer ◽  
Surface Textures ◽  
Microscope Images ◽  
The Coefficient Of Friction ◽  
Plate Apparatus

Surface texture influences friction during sliding. In the present investigation, experiments were conducted using an inclined pin-on-plate apparatus to study the tribological response of metals and polymers during sliding against various surface textures. In the experiments, metals (Pb and Sn) and polymers (PP and PVC) were used for the pin and hardened steel was used for the plate. Experiments were conducted under both dry and lubricated conditions in an ambient environment. Two surface parameters of the steel plates — roughness and texture — were varied in the experiments. Using scanning electron microscope images, the surfaces of both the plate and pin materials were examined to determine the transfer layer formation on the plate and the wear of the pins. Based on the experimental results, it was observed that the transfer layer formation and the coefficient of friction were controlled by the surface texture of the plates. Moreover, both polymers and metals exhibited similar frictional responses, but the metals had a significantly larger variation in friction with surface texture.

Studies on Friction and Transfer Layer Formation When Pure Magnesium Pins Slid at Various Numbers of Cycles on Steel Plates of Different Surface Texture

2010 ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas ◽  
Michael R. Lovell
Keyword(s):  
Coefficient Of Friction ◽  
Surface Texture ◽  
Pure Magnesium ◽  
Steel Plates ◽  
Transfer Layer ◽  
Stick Slip ◽  
Die Surface ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Number Of Cycles

In the present investigation, various kinds of textures (undirectional, 8-ground, and random,) were attained on a set of steel plate surfaces. The roughness of the textures was varied using different grits of emery papers or polishing powders. Pins made of pure magnesium were then slid against the steel plates at various numbers of cycles (1, 2, 6, 10 and 20) using an inclined pin-on-plate sliding apparatus. In the experiments, it was observed that the coefficient of friction and the formation of a transfer layer depended on the die surface textures under both dry and lubricated conditions. The coefficient of friction increased with number of cycles under dry conditions for all of the textures studied. Under lubricated conditions, however, the coefficient of friction decreased for unidirectional and 8-ground surfaces and increased for random surfaces with the number of cycles. A stick-slip phenomenon was observed under both dry and lubricated conditions. Occurrence of the stick slip behavior depended on the surface texture, the load and the number of cycles. The variation in the coefficient of friction under both dry and lubrication conditions was attributed to changes in the texture of the surfaces during sliding.

Influence of Inclination Angle and Machining Direction on Friction and Transfer Layer Formation

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas ◽  
Michael R. Lovell
Keyword(s):  
Plane Strain ◽  
Coefficient Of Friction ◽  
Inclination Angle ◽  
Sliding Contact ◽  
Steel Plates ◽  
Layer Formation ◽  
Transfer Layer ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Slip Phenomenon

In the present investigation, unidirectional grinding marks were created on a set of steel plates. Sliding experiments were then conducted with the prepared steel plates using Al–Mg alloy pins and an inclined pin-on-plate sliding tester. The goals of the experiments were to ascertain the influence of inclination angle and grinding mark direction on friction and transfer layer formation during sliding contact. The inclination angle of the plate was held at 0.2 deg, 0.6 deg, 1 deg, 1.4 deg, 1.8 deg, 2.2 deg, and 2.6 deg in the tests. The pins were slid both perpendicular and parallel to the grinding marks direction. The experiments were conducted under both dry and lubricated conditions on each plate in an ambient environment. Results showed that the coefficient of friction and the formation of transfer layer depend on the grinding marks direction and inclination angle of the hard surfaces. For a given inclination angle, under both dry and lubricated conditions, the coefficient of friction and transfer layer formation were found to be greater when the pins slid perpendicular to the unidirectional grinding marks than when the pins slid parallel to the grinding marks. In addition, a stick-slip phenomenon was observed under lubricated conditions at the highest inclination angle for sliding perpendicular to the grinding marks direction. This phenomenon could be attributed to the extent of plane strain conditions taking place at the asperity level during sliding.

Influence of Surface Textures During Metal Forming

2007 ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas
Keyword(s):  
Flow Pattern ◽  
Coefficient Of Friction ◽  
Surface Texture ◽  
Metal Forming ◽  
Metal Flow ◽  
Steel Plates ◽  
Work Piece ◽  
Layer Formation ◽  
Transfer Layer ◽  
The Coefficient Of Friction

Friction plays an important role in metal forming processes. In the present investigation, various kinds of surface texture with varying roughness were produced on steel plates. Pins made of Al-8Mg alloy were then slid against the prepared steel plates using inclined pin-on-plate sliding tester to understand the role of surface texture of the harder surface and load on coefficient of friction and transfer layer formation under both dry and lubricated conditions. It was observed that both the coefficient of friction and transfer layer formation are highly dependent on the surface texture of harder counterface. Numerical analysis of simulated compression test, assigning different magnitude of coefficient of friction at different regions between the die and work piece, was carried out to understand the effect of friction on deformation and stress distribution. Results of simulation revealed that, owing to the difference in coefficient of friction, there is a difference in metal flow pattern. Both experimental and numerical results confirmed that the surface texture of the die surface and thus coefficient of friction directly affects the strain rate and flow pattern of the work-piece.

Influence of Inclination Angle and Surface Texture of the Plate on Friction and Transfer Layer Formation

2009 ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas ◽  
Michael R. Lovell
Keyword(s):  
Coefficient Of Friction ◽  
Inclination Angle ◽  
Tilt Angle ◽  
Steel Plates ◽  
Hard Material ◽  
Layer Formation ◽  
Transfer Layer ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Slip Phenomenon

In the present investigation, unidirectional grinding marks were attained on the steel plates. Experiments were then conducted using pins of Al-Mg alloy against the prepared steel plates using an inclined pin-on-plate sliding tester. The goal of the research is to understand the influence of grinding mark direction and inclination angle of hard material on the friction and transfer layer formation during sliding. The inclination angle of the plate was held at 0.2°, 0.6°, 1°, 1.4°, 1.8°, 2.2° and 2.6° in the tests. The pins were slid both perpendicular and parallel to the grinding marks direction. Experiments were conducted under both dry and lubricated conditions on each plate in ambient environment. Results showed that the coefficient of friction and formation of transfer layer depend on the grinding marks direction and inclination angle of the hard surfaces. For a given inclination angle, the coefficient of friction and transfer layer formation were found to be more for the pins slid perpendicular to the unidirectional grinding marks when compared to parallel to the unidirectional grinding marks under both dry and lubricated conditions. The stick-slip phenomenon was observed only under lubricated conditions at the highest tilt angle for the sliding perpendicular to the grinding marks direction. These variations could be attributed to the extent of plane strain conditions taking place at the asperity level during sliding.

scholarly journals Topology assisted self-organization of colloidal nanoparticles: application to 2D large-scale nanomastering

2014 ◽  
Vol 5 ◽  
pp. 1203-1209 ◽  
Author(s):  
Hind Kadiri ◽  
Serguei Kostcheev ◽  
Daniel Turover ◽  
Rafael Salas-Montiel ◽  
Komla Nomenyo ◽  
...  
Keyword(s):  
Large Scale ◽  
The Self ◽  
Surface Topology ◽  
Self Organization ◽  
Hydrogen Silsesquioxane ◽  
Polystyrene Beads ◽  
Structure Topology ◽  
Self Organized ◽  
Novel Method ◽  
Long Range Ordering

Our aim was to elaborate a novel method for fully controllable large-scale nanopatterning. We investigated the influence of the surface topology, i.e., a pre-pattern of hydrogen silsesquioxane (HSQ) posts, on the self-organization of polystyrene beads (PS) dispersed over a large surface. Depending on the post size and spacing, long-range ordering of self-organized polystyrene beads is observed wherein guide posts were used leading to single crystal structure. Topology assisted self-organization has proved to be one of the solutions to obtain large-scale ordering. Besides post size and spacing, the colloidal concentration and the nature of solvent were found to have a significant effect on the self-organization of the PS beads. Scanning electron microscope and associated Fourier transform analysis were used to characterize the morphology of the ordered surfaces. Finally, the production of silicon molds is demonstrated by using the beads as a template for dry etching.

Self-Organization and Trade Union Democracy

2000 ◽  
Vol 48 (2) ◽  
pp. 262-282 ◽  
Author(s):  
Jill C. Humphrey
Keyword(s):  
Trade Union ◽  
The Self ◽  
Self Organization ◽  
Public Sector Union ◽  
Self Organized ◽  
Union Democracy ◽  
Democratic Polity ◽  
Late Twentieth ◽  
Three Stages ◽  
Late Twentieth Century

This article is an offshoot of a three year study into the self-organized groups for women, black members, disabled members and lesbians and gay men which have been enshrined in the constitution of the UK's public sector union UNISON. The argument is that self-organization has become a significant axis around which trade union democracy is being reconstituted in the late twentieth century. However, our understanding of this phenomenon has been obscured by the ascendancy of mainstream union perspectives over self-organized perspectives, which has unfortunately been compounded by academic researchers. A re-conceptualization of self-organization proceeds in three stages. First, it is contextualized politically and theoretically in terms of trade union histories, new social movements and models of a diversified democratic polity. Second, it is re-signified by attending to its actual unfolding over the past two decades and the self-understandings of its activists. Third, is problematized with reference to exogenous pressures towards bureaucracy and oligarchy, and endogenous pressures towards essentialisms and exclusions.

scholarly journals Transition from Self-Organized Criticality into Self-Organization during Sliding Si3N4 Balls against Nanocrystalline Diamond Films

Entropy ◽  
2019 ◽  
Vol 21 (11) ◽  
pp. 1055
Author(s):  
Bogatov ◽  
Podgursky ◽  
Vagiström ◽  
Yashin ◽  
Shaikh ◽  
...  
Keyword(s):  
Friction Force ◽  
Power Law ◽  
Early Stage ◽  
Nanocrystalline Diamond ◽  
The Self ◽  
Self Organization ◽  
Power Law Distribution ◽  
Reciprocating Sliding ◽  
Self Organized ◽  
Self Organized Criticality

The paper investigates the variation of friction force (Fx) during reciprocating sliding tests on nanocrystalline diamond (NCD) films. The analysis of the friction behavior during the run-in period is the focus of the study. The NCD films were grown using microwave plasma-enhanced chemical vapor deposition (MW-PECVD) on single-crystalline diamond SCD(110) substrates. Reciprocating sliding tests were conducted under 500 and 2000 g of normal load using Si3N4 balls as a counter body. The friction force permanently varies during the test, namely Fx value can locally increase or decrease in each cycle of sliding. The distribution of friction force drops (dFx) was extracted from the experimental data using a specially developed program. The analysis revealed a power-law distribution f-µ of dFx for the early stage of the run-in with the exponent value (µ) in the range from 0.6 to 2.9. In addition, the frequency power spectrum of Fx time series follows power-law distribution f-α with α value in the range of 1.0–2.0, with the highest values (1.6–2.0) for the initial stage of the run-in. No power-law distribution of dFx was found for the later stage of the run-in and the steady-state periods of sliding with the exception for periods where a relatively extended decrease of coefficient of friction (COF) was observed. The asperity interlocking leads to the stick-slip like sliding at the early stage of the run-in. This tribological behavior can be related to the self-organized criticality (SOC). The emergence of dissipative structures at the later stages of the run-in, namely the formation of ripples, carbonaceous tribolayer, etc., can be associated with the self-organization (SO).

Studies on Friction and Formation of Transfer Layer in HCP Metals

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Pradeep L. Menezes ◽  
Kishore ◽  
Satish V. Kailas ◽  
Michael R. Lovell
Keyword(s):  
Surface Texture ◽  
Steel Plates ◽  
Ambient Conditions ◽  
Transfer Layer ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Hcp Materials ◽  
Stick Slip Motion ◽  
Slip Motion

Surface texture plays an important role in the frictional behavior and transfer layer formation of contacting surfaces. In the present investigation, basic experiments were conducted using an inclined pin-on-plate sliding apparatus to better understand the role of surface texture on the coefficient of friction and the formation of a transfer layer. In the experiments, soft HCP materials such as pure Mg and pure Zn were used for the pins and a hardened 080 M40 steel was used for the plate. Two surface parameters of the steel plates—roughness and texture—were varied in tests that were conducted at a sliding speed of 2 mm/s in ambient conditions under both dry and lubricated conditions. The morphologies of the worn surfaces of the pins and the formation of the transfer layer on the counter surfaces were observed using a scanning electron microscope. In the experiments, the occurrence of stick-slip motion, the formation of a transfer layer, and the value of friction were recorded. With respect to the friction, both adhesion and plowing components were analyzed. Based on the experimental results, the effect of surface texture on the friction was attributed to differences in the amount of plowing. Both the plowing component of friction and the amplitude of stick-slip motion were determined to increase surface textures that promote plane strain conditions and decrease the textures that favor plane stress conditions.

Influence of Resin Viscosity and Filler Volume on Self-Organized Micro Interconnection

2006 ◽  
Vol 512 ◽  
pp. 367-372 ◽  
Author(s):  
Kiyokazu Yasuda ◽  
Koushi Ohta ◽  
Kozo Fujimoto
Keyword(s):  
Dispersion Model ◽  
Volume Ratio ◽  
The Self ◽  
Self Organization ◽  
The Novel ◽  
Self Organized ◽  
Assembly Method ◽  
Real Process ◽  
Optimal Value ◽  
Filler Dispersion

The novel selective interconnection using the resin containing low-melting-point-alloy fillers was developed as a high density assembly method of a low-temperature and highly reliable electronic interconnection. By means of the coalescence of fillers and wetting onto the terminal material due to the Laplace pressure of the fillers, self-organization onto the terminals was formed. The influence of the filler volume ratio and resin viscosity on the self-organized interconnecting was investigated by the numerical analysis with a multi-filler dispersion model corresponding to a real process, and was evaluated by using the normalized parameter (self-organization ratio). We clarified the existence of the optimal value of the filler volume ratio. The rate controlling factor transferred from the filler volume to the inflow velocity by the increase of the viscosity.

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