scholarly journals The Tribological Adaptability for Ventral Scales of Dinodon rufozonatum in Dry/Wet/Rough Environments

Coatings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 20
Author(s):  
Song Hu ◽  
Ge Shi ◽  
Qinggang Guo ◽  
Long Zheng ◽  
Luquan Ren ◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Water Lubrication ◽  
Substrate Roughness ◽  
Contact Conditions ◽  
Frictional Performance ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Multiple Environments ◽  
Lubrication Conditions

The ventral scales of Dinodon rufozonatum were investigated to understand the outstanding tribological adaptability in various environments. The coefficient of friction (COF) of ventral scales was measured and changed with the contact conditions. It was discovered that the COF of scales under water-lubrication conditions (WLC) was larger than that under dry conditions (DC). More interestingly, the COF increased first and then decreased as the substrate roughness reduced. The abrasion marks on scales were then observed. The results indicated that the scales in DC wore more gently than that in WLC. Moreover, the degree of wear reduced with the decrease of substrate roughness. The frictional performance of ventral scales enabled the snakes to move more efficiently, quickly, and flexibly in multiple environments.

scholarly journals Solid Lubrication by Multiwalled Carbon Nanotubes in Air and in Vacuum for Space and Aeronautics Applications

2005 ◽  
Author(s):  
K. Miyoshi ◽  
K. W. Street ◽  
R. L. Vander Wal ◽  
R. Andrews ◽  
David Jacques ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Solid Lubrication ◽  
Multiwalled Carbon ◽  
Solid Lubrication Friction ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Steel Balls

To evaluate recently developed aligned multiwalled carbon nanotubes (MWNTs) and dispersed MWNTs for solid lubrication applications, unidirectional sliding friction experiments were conducted with 440C stainless steel balls and hemispherical alumina-yttria stabilized zirconia pins in sliding contact with the MWNTs deposited on quartz disks in air and in vacuum. The results indicate that MWNTs have superior solid lubrication friction properties and endurance lives in air and vacuum under dry conditions. The coefficient of friction of the dispersed MWNTs is close to 0.05 and 0.009 in air and in vacuum, respectively, showing good dry lubricating ability. The wear life of MWNTs exceeds 1 million passes in both air and vacuum showing good durability. In general, the low coefficient of friction can be attributed to the combination of the transferred, agglomerated patches of MWNTs on the counterpart ball or pin surfaces and the presence of tubular MWNTs at interfaces.

FLOOR SLIPPERINESS MEASUREMENT UNDER SPILLAGE CONDITION

2015 ◽  
Vol 77 (27) ◽  
Author(s):  
Norazrin Azwani Ahmad ◽  
Masine Md. Tap ◽  
Ardiyanshah Syahrom ◽  
Jafri Mohd Rohani ◽  
Mohamed Fitri Johari
Keyword(s):  
Coefficient Of Friction ◽  
Friction Loss ◽  
Skid Resistance ◽  
Surface Conditions ◽  
The Coefficient Of Friction ◽  
Dry Conditions

To understand the risk of slipping accidents in the industry, it is imperative to measure the coefficient of friction (COF) between footwear and floor. In this study, COF values were measured for four types of floor with five surface conditions that represent dry conditions and four liquid spillage conditions. A portable skid-resistance tester was used to measure the COF with three footwear materials attached on the slider. The results show that the interaction between floor type, footwear material, and surface conditions was significant (p< 0.0001). Variation of COF value was found due to different footwear materials and floors involved during the interaction. The friction loss results also conclude that the COF became reduced significantly in all footwear-floor conditions (in the range of 17% to 78%) in the presence of spillage on the floor. 

Analysis of the Contribution of Adhesion and Ploughing to Shoe-Floor Lubricated Friction in the Boundary Lubrication Regime

2011 ◽  
Author(s):  
Caitlin Moore ◽  
Kurt Beschorner ◽  
Pradeep L. Menezes ◽  
Michael R. Lovell
Keyword(s):  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
Ambient Conditions ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Material Hardness ◽  
Lubrication Layer ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Pin On Disk

Slip and fall accidents cost billions of dollars each year. Shoe-floor-lubricant friction has been shown to follow the Stribeck effect, operating primarily in the boundary and mixed-lubrication regimes. Two of the most important factors believed to significantly contribute to shoe-floor-lubricant friction in the boundary lubrication regime are adhesion and ploughing. Experiments were conducted using a pin-on-disk tribometer to quantify adhesion and ploughing contributions to shoe-floor friction in dry and lubricated conditions. The coefficient of friction between three shoe materials and two floor materials of different hardness and roughness were considered. Experiments were conducted under six lubricants for a sliding speed of 0.01 m/sec at ambient conditions. It was found that the contribution of adhesion and ploughing to shoe-floor-lubricant friction was significantly affected by material hardness, roughness, and lubricant properties. Material hardness and roughness are known to affect adhesion, with increased hardness or increased roughness typically resulting in decreased adhesion. The smoothest shoe material, while also being the hardest, resulted in the greatest adhesional contribution to friction. The roughest material, while also being the softest, resulted in the lowest adhesional contributions under dry conditions. Canola oil consistently resulted in the lowest percent of full adhesion and water consistently resulted in the highest percent of full adhesion, presumably due to the thickness, of the boundary lubrication layer. Ploughing contribution was dependent upon the hardness of the shoe and floor materials. A positive correlation was found between the shoe and floor hardness ratio and ploughing coefficient of friction.

EXPERIMENTAL STUDY OF THE ROLLING–SLIDING CONTACT CONDITIONS IN A PA66/STEEL GEAR USING TWIN-DISC TEST RIG: FRICTION AND WEAR ANALYSIS

2015 ◽  
Vol 22 (06) ◽  
pp. 1550074
Author(s):  
MEFTAH MBAREK ◽  
SADOK RHAIEM ◽  
MOHAMED KHARRAT ◽  
MAHER DAMMAK
Keyword(s):  
Coefficient Of Friction ◽  
Angular Speed ◽  
Linear Increase ◽  
Contact Temperature ◽  
Test Rig ◽  
Contact Conditions ◽  
Slip Ratio ◽  
The Coefficient Of Friction ◽  
Adhesive Interactions ◽  
Different Diameters

This study investigates the effects of sliding ratio on the tribological response of the contact between the teeth of a metal/polymer gear in the regions close to the pitch point. For this purpose, a new twin-disc test rig was developed on the basis of two discs of different diameters rotating one above the other at the same angular speed. Two different materials were used: non-alloyed structural steel (C45) and polyamide (PA66). The effect of the slip ratio (4%, 12%, 20% and 28%) was studied at a constant pressure of 34 MPa and a constant angular speed of 300 rpm. In addition, the contact conditions were controlled with measurements of the two discs surface temperatures. The results indicate that the wear and the friction are closely related to the contact temperature generated by the sliding phenomenon. At low slip ratio (4% and 12%), the coefficient of friction and the temperature are characterized by a quasi-linear increase with time, and the wear increases slowly. At higher slip ratio (20% and 28%), the coefficient of friction and the temperature presents a steady state, and the wear increases dramatically. During the test, a film of transferred PA66 is formed on the steel surface causing the development of adhesive interactions between the contacting discs which increase the friction coefficient and the contact temperature. The high thermal conductivity of steel as compared to that of the polymer can reduce enormously the contact temperature generated by the sliding process.

scholarly journals An Experimental Study of the Frictional Properties of Steel Sheets Using the Drawbead Simulator Test

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4037 ◽  
Author(s):  
Trzepiecinski ◽  
Kubit ◽  
Slota ◽  
Fejkiel
Keyword(s):  
Coefficient Of Friction ◽  
Extreme Values ◽  
Rolling Direction ◽  
Frictional Resistance ◽  
Friction Reduction ◽  
Experimental Investigations ◽  
Sheet Rolling ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
Lubrication Conditions

This article presents the results of an experimental investigation of the frictional resistance arising in a drawbead during sheet metal forming. The frictional characterization of DC04 deep drawing quality steels commonly used in the automotive industry is carried out using a friction simulator. The effects of some parameters of the friction process on the value of the coefficient of friction have been considered in the experimental investigations. The friction tests have been conducted on different strip specimens, lubrication conditions, heights of drawbead and specimen orientations in relation to the sheet rolling direction. The results of drawbead simulator tests demonstrate the relationship that the value of the coefficient of friction of the test sheets without lubrication is higher than in the case of lubricated sheets. The lubricant reduces the coefficient of friction, but the effectiveness of its reduction depends on the drawbead height and lubrication conditions. Moreover, the effectiveness of the reduction of the coefficient of friction by the lubricant depends on the specimen orientation according to the sheet rolling direction. In the drawbead test, the specimens oriented along the rolling direction demonstrate a higher value of coefficient of friction when compared to the samples cut transverse to the rolling direction. The smaller the width of the specimen, the lower the coefficient of friction observed. The difference in the coefficient of friction for the extreme values of the widths of the specimens was about 0.03–0.05. The use of machine oil reduced the coefficient of friction by 0.02–0.03 over the whole range of drawbead heights. Heavy duty lubricant even reduced the frictional resistances by over 50% compared to dry friction conditions. The effectiveness of friction reduction by machine oil does not exceed 30%.

Experimental Investigation of Porous Bronze Bearings

1973 ◽  
Vol 95 (2) ◽  
pp. 173-179 ◽  
Author(s):  
C. Cusano ◽  
R. M. Phelan
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
Operating Conditions ◽  
The Coefficient Of Friction ◽  
Theoretical Analyses ◽  
Lubrication Conditions

An experimental study was made of the performance of porous bronze bearings under different operating conditions. A PV value of 50,000 psi ft/min was found to be too high for the assembly used when the bearings were lubricated only by the oil initially provided within their structure. Tests at a PV value of 33,000 psi ft/min gave satisfactory results. The coefficient of friction was found to vary with load and to be almost independent of speed for the bearings tested under boundary lubrication conditions. Except for relatively light loads and moderate and higher speeds, the bearings operate under boundary lubrication conditions. When pressurized oil was supplied to the bearings, it was found that, for the same operating conditions, porous bearings run at higher eccentricity ratios than solid bearings, as predicted by theoretical analyses.

A Simplified Method for Wear Loss Prediction in Corrosive Environment

2013 ◽  
Vol 436 ◽  
pp. 121-126
Author(s):  
Zinaida Doni ◽  
Mihaela Buciumeanu ◽  
Liviu Palaghian
Keyword(s):  
Wear Loss ◽  
Corrosive Environment ◽  
Contact Conditions ◽  
Wear And Corrosion ◽  
Simplified Method ◽  
Loss Prediction ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Combined Action ◽  
Contact Surfaces

The interaction of wear and corrosion is an important factor of the combined action of mechanical and corrosive damage. Many authors have studied the synergistic effect between wear and corrosion under different contact conditions. In the present paper is proposed a simplified method to predict wear evolution of contact surfaces in corrosive environment based on the wear loss evolution in dry conditions and on the coefficient of friction in corrosive environment. The proposed method is adequate to properly predict the wear loss evolution.

A Deep Drawing Test for Determining the Punch Coefficient of Friction

1981 ◽  
Vol 103 (2) ◽  
pp. 197-202 ◽  
Author(s):  
S. Rajagopal
Keyword(s):  
Experimental Data ◽  
Coefficient Of Friction ◽  
Deep Drawing ◽  
Stress System ◽  
Drawing Test ◽  
The Coefficient Of Friction ◽  
Cylindrical Region ◽  
Deep Drawing Test ◽  
Lubrication Conditions

A deep drawing test is described for measuring the coefficient of friction between the cylindrical surfaces of the punch and the cup wall. The test is based on an analysis of the stress system in the cylindrical region of contact. Experimental data are presented for steel and aluminum blanks deep-drawn into cups under different lubrication conditions, and the advantages and limitations of the method are discussed.

Slip Sliding Away — Slip Resistance of Athletic Socks on Indoor Flooring

2009 ◽  
Vol 53 (9) ◽  
pp. 568-571
Author(s):  
David G. Curry ◽  
Anne Mathias
Keyword(s):  
Coefficient Of Friction ◽  
Laboratory Study ◽  
Published Data ◽  
Slip Resistance ◽  
Significant Difference ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Flooring Materials

A laboratory study was conducted to assess the slip resistance of athletic socks on various household flooring materials under both wet and dry conditions. While prior studies regarding slip resistance have focused on shod walkers, there is a lack of published data on the coefficient of friction between stocking-clad feet and indoor flooring. To investigate this, four types of athletic socks were tested on samples of eight flooring materials for both wet and dry conditions. These results were compared to tests of a Neolite slider pad on these floors. The results indicated that for socks on textured vinyl flooring, there was no significant difference in slip resistance between the wet and dry conditions, though there was a trend towards greater slip resistance under wet conditions. Generally, it appears that the likelihood of slipping on other types of wet indoor walking surfaces is lower when walking in socks rather than shoes.

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