scholarly journals Mechanics of wedge turns in alpine skiing

2020 ◽  
Author(s):  
Serguei Komissarov
Keyword(s):  
Coefficient Of Friction ◽  
Experimental Investigations ◽  
Approximate Theory ◽  
Alpine Skiing ◽  
The Coefficient Of Friction

A simple approximate theory of snow machining is applied to modelling successive wedge turns of alpine skiing. The results are in agreement with available experimental investigations of such turns. In particular, the model explains the abnormally high values for the coefficient of friction reported in these studies.

scholarly journals Friction Behavior of Pre-Damaged Wet-Running Multi-Plate Clutches in an Endurance Test

Lubricants ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 68
Author(s):  
Thomas Schneider ◽  
Katharina Voelkel ◽  
Hermann Pflaum ◽  
Karsten Stahl
Keyword(s):  
Coefficient Of Friction ◽  
Later Life ◽  
Second Step ◽  
Experimental Investigations ◽  
Endurance Test ◽  
Friction Behavior ◽  
Speed Range ◽  
The Coefficient Of Friction ◽  
Endurance Tests

Wet-running multi-plate clutches should be prevented from failing due to the often safety-relevant functions they fulfill in the drive train. In addition to long-term damage, spontaneous damage is of particular relevance for failures. This paper focuses on the influence of spontaneous damage on frictional behavior in the later life cycle. The aim of the experimental investigations is to initially cause spontaneous damage in wet-running multi-plate clutches with sintered friction linings. For this purpose, three clutches are first pre-damaged in stage tests with different intensities, so that the first spontaneous damage (local discoloration, sinter transfer) occurs. In the second step, an endurance test is carried out with the pre-damaged clutch packs and a non-pre-damaged reference clutch. The friction behavior of the clutches during the endurance test is compared and evaluated. It shows that local discoloration and sinter transfer are no longer visible after the endurance tests. At the beginning of the endurance test, the values of coefficient of friction are higher over the entire speed range of the heavily pre-damaged clutches than with the slightly pre-damaged clutch and the non-pre-damaged reference clutch. At the end of the endurance test, it can be observed that the greater the pre-damage to the clutches is, the greater the coefficient of friction increases with decreasing sliding speed.

The Design of a Linear “Out of Phase” Vibratory Conveyor

1973 ◽  
Vol 95 (1) ◽  
pp. 42-47 ◽  
Author(s):  
R. E. Schofield ◽  
M. Yousuf
Keyword(s):  
Phase Angle ◽  
Coefficient Of Friction ◽  
Experimental Investigations ◽  
Phase Effect ◽  
Theoretical Predictions ◽  
The Coefficient Of Friction ◽  
Drive Belt ◽  
The Mean ◽  
Vibratory Conveyor ◽  
Normal Track

This paper describes the development of a linear “out-of-phase” vibratory conveyor. The “out-of-phase” effect is achieved by controlling the components of motion normal to and parallel to the track independently. This is done by mounting the trough on sets of double “U” shear rubber mountings. From Fig. 1(a) it can be seen that these mountings allow motion in any direction in the plane of the rubber while substantially constraining motion perpendicular to that plane. Excitation of the trough is by two hydraulic pumps the phase angle between which is controlled by a positive drive belt. Experimental investigations into the behavior of single parts were carried out and results comparable to the theoretical predictions for “out-of-phase” were obtained. Substantial increases in the mean conveying velocity of single parts can be achieved without erratic part movement because it is possible with this system to use high values of normal track acceleration An/g combined with low vibration angles. Increases in mean conveying velocity of as much as 270 percent are obtained, depending on the coefficient of friction and vibration angles.

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 aluminum doping crumb rubber/epoxy composite in reciprocating motion

2015 ◽  
Vol 3 ◽  
pp. 1
Author(s):  
Goutam Chandra Karar ◽  
Nipu Modak
Keyword(s):  
Experimental Investigation ◽  
Coefficient Of Friction ◽  
Epoxy Composite ◽  
Normal Load ◽  
Crumb Rubber ◽  
The Other ◽  
Reciprocating Motion ◽  
Molding Process ◽  
Friction Tester ◽  
The Coefficient Of Friction

The experimental investigation of reciprocating motion between the aluminum doped crumb rubber /epoxy composite and the steel ball has been carried out under Reciprocating Friction Tester, TR-282 to study the wear and coefficient of frictions using different normal loads (0.4Kg, 0.7Kgand1Kg), differentfrequencies (10Hz, 25Hz and 40Hz).The wear is a function of normal load, reciprocating frequency, reciprocating duration and the composition of the material. The percentage of aluminum presents in the composite changesbut the other components remain the same.The four types of composites are fabricated by compression molding process having 0%, 10%, 20% and 30% Al. The effect of different parameters such as normal load, reciprocating frequency and percentage of aluminum has been studied. It is observed that the wear and coefficient of friction is influenced by the parameters. The tendency of wear goes on decreasing with the increase of normal load and it is minimum for a composite having 10%aluminum at a normal load of 0.7Kg and then goes on increasing at higher loads for all types of composite due to the adhesive nature of the composite. The coefficient of friction goes on decreasing with increasing normal loads due to the formation of thin film as an effect of heat generation with normal load.

scholarly journals Tribological Aspects, Optimization and Analysis of Cu-B-CrC Composites Fabricated by Powder Metallurgy

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4217
Author(s):  
Üsame Ali Usca ◽  
Mahir Uzun ◽  
Mustafa Kuntoğlu ◽  
Serhat Şap ◽  
Khaled Giasin ◽  
...  
Keyword(s):  
Weight Loss ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Applied Load ◽  
Practical Significance ◽  
Tribological Characteristics ◽  
M 10 ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Four Levels

Tribological properties of engineering components are a key issue due to their effect on the operational performance factors such as wear, surface characteristics, service life and in situ behavior. Thus, for better component quality, process parameters have major importance, especially for metal matrix composites (MMCs), which are a special class of materials used in a wide range of engineering applications including but not limited to structural, automotive and aeronautics. This paper deals with the tribological behavior of Cu-B-CrC composites (Cu-main matrix, B-CrC-reinforcement by 0, 2.5, 5 and 7.5 wt.%). The tribological characteristics investigated in this study are the coefficient of friction, wear rate and weight loss. For this purpose, four levels of sliding distance (1000, 1500, 2000 and 2500 m) and four levels of applied load (10, 15, 20 and 25 N) were used. In addition, two levels of sliding velocity (1 and 1.5 m/s), two levels of sintering time (1 and 2 h) and two sintering temperatures (1000 and 1050 °C) were used. Taguchi’s L16 orthogonal array was used to statistically analyze the aforementioned input parameters and to determine their best levels which give the desired values for the analyzed tribological characteristics. The results were analyzed by statistical analysis, optimization and 3D surface plots. Accordingly, it was determined that the most effective factor for wear rate, weight loss and friction coefficients is the contribution rate. According to signal-to-noise ratios, optimum solutions can be sorted as: the highest levels of parameters except for applied load and reinforcement ratio (2500 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 °C and 0 wt.% for the coefficient of friction. The comprehensive analysis of findings has practical significance and provides valuable information for a composite material from the production phase to the actual working conditions.

scholarly journals Influence of Beam Power on Young’s Modulus and Friction Coefficient of Ti–Ta Alloys Formed by Electron-Beam Surface Alloying

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1246
Author(s):  
Stefan Valkov ◽  
Dimitar Dechev ◽  
Nikolay Ivanov ◽  
Ruslan Bezdushnyi ◽  
Maria Ormanova ◽  
...  
Keyword(s):  
Electron Beam ◽  
Young’S Modulus ◽  
Coefficient Of Friction ◽  
Young's Modulus ◽  
Beam Power ◽  
Surface Alloying ◽  
Surface Alloys ◽  
X Ray ◽  
The Coefficient Of Friction ◽  
Beam Surface

In this study, we present the results of Young’s modulus and coefficient of friction (COF) of Ti–Ta surface alloys formed by electron-beam surface alloying by a scanning electron beam. Ta films were deposited on the top of Ti substrates, and the specimens were then electron-beam surface alloyed, where the beam power was varied from 750 to 1750 W. The structure of the samples was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Young’s modulus was studied by a nanoindentation test. The coefficient of friction was studied by a micromechanical wear experiment. It was found that at 750 W, the Ta film remained undissolved on the top of the Ti, and no alloyed zone was observed. By an increase in the beam power to 1250 and 1750 W, a distinguished alloyed zone is formed, where it is much thicker in the case of 1750 W. The structure of the obtained surface alloys is in the form of double-phase α’and β. In both surface alloys formed by a beam power of 1250 and 1750 W, respectively, Young’s modulus decreases about two times due to different reasons: in the case of alloying by 1250 W, the observed drop is attributed to the larger amount of the β phase, while at 1750 W is it due to the weaker binding forces between the atoms. The results obtained for the COF show that the formation of the Ti–Ta surface alloy on the top of Ti substrate leads to a decrease in the coefficient of friction, where the effect is more pronounced in the case of the formation of Ti–Ta surface alloys by a beam power of 1250 W.

Reducing the Coefficient of Friction for Fast-Absorbing Gut Suture

2009 ◽  
Vol 35 (12) ◽  
pp. 2004 ◽  
Author(s):  
Jonathan Lee Bingham ◽  
Mariah R. Brown ◽  
Julian Ramsey Mellette
Keyword(s):  
Coefficient Of Friction ◽  
The Coefficient Of Friction

First Paper: Effect of Under-Lip Temperature on the Lubrication of Rotary Shaft Garter Spring Seals

1966 ◽  
Vol 181 (1) ◽  
pp. 185-190 ◽  
Author(s):  
D. J. Lines ◽  
J. M. Lawrie ◽  
J. P. O'Donoghue
Keyword(s):  
Coefficient Of Friction ◽  
Operating Temperature ◽  
Lubrication Theory ◽  
Fluid Film ◽  
Hydrodynamic Parameter ◽  
Accurate Knowledge ◽  
The Coefficient Of Friction ◽  
Surface Thermocouple ◽  
Sealing Mechanism ◽  
Film Lubrication

Although rotary shaft garter spring seals are widely used throughout industry, very little is known about the sealing mechanism of the lip-shaft interface. It is now generally accepted that some sort of fluid film separates the lip and the shaft. Previous workers have also postulated a relationship between the coefficient of friction and a non-dimensional hydrodynamic parameter, as in standard lubrication theory. This present paper clarifies this relationship, and shows that seals can also operate over the mixed friction, as well as the full film lubrication region. The results were obtained by accurate knowledge of the operating temperature under the sealing lip. Two types of surface thermocouple were developed to do this and these are described in full.

The Effect of Nanoparticle Functionalization on Lubrication Performance of Nanofluids Dispersing Silica Nanoparticles in an Ionic Liquid

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Cengiz Yegin ◽  
Wei Lu ◽  
Bassem Kheireddin ◽  
Ming Zhang ◽  
Peng Li ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
Coefficient Of Friction ◽  
Shear Thinning ◽  
Antiwear Additives ◽  
Functionalized Silica ◽  
Low Concentrations ◽  
Lubrication Performance ◽  
The Coefficient Of Friction ◽  
High Concentrations ◽  
Newtonian Behavior

Recently, ionic liquids (ILs) have received an increasing attention as lubricants owing to their intriguing properties such as tunable viscosity, high thermal stability, low emissions, nonflammability, and corrosion resistance. In this work, we investigate how the incorporation of octadecyltrichlorosilane (OTS) functionalized silica nanoparticles (NPs) in 1-butyl-3-methylimidazolium (trifluoromethysulfony)imide influences the tribological properties and rheological properties of IL under boundary lubrication and elastohydrodynamic conditions, respectively. It was found that the coefficient of friction was depended on the concentration of NPs in IL with a concave upward functional trend with a minimum at 0.05 wt.% for bare silica NPs and at 0.10 wt.% for OTS-functionalized silica NPs. For steel–steel sliding contact, the presence of functionalized NPs in IL at the optimum concentration decreased the coefficient of friction by 37% compared to IL and 17% compared to IL with bare silica NPs. While IL with bare NPs demonstrated a shear thinning behavior for all concentrations, IL with functionalized NPs showed a Newtonian behavior at low concentrations and shear thinning behavior at high concentrations. Overall, this study provides new insights into the antifriction and antiwear additives for lubrication systems involving ILs.

Sign in / Sign up

Export Citation Format

Share Document