METHOD OF MEASURING FRICTIONAL RESISTANCE IN PENDULAR MOTION

Tribologia ◽  
2021 ◽  
Vol 295 (1) ◽  
pp. 15-19
Author(s):  
Mariusz Opałka
Keyword(s):  
Kinetic Energy ◽  
Coefficient Of Friction ◽  
Frictional Resistance ◽  
Measuring Time ◽  
Friction Coefficients

This paper presents a methodology for conducting tribological sliding tests based on decaying vibrations in pendular motion. The proposed method of determining the (averaged) coefficient of friction in pendular motion is based on measuring the potential kinetic energy. The method is characterized by a short measuring time and enables a quick comparison of the friction coefficients of different materials.

Theoretical and experimental investigation of non-asbestos friction lining material applied in automotive drum brake

2019 ◽  
Vol 234 (6) ◽  
pp. 972-985
Author(s):  
Dinesh Subhash Shinde ◽  
KN Mistry ◽  
Mukesh Bulsara
Keyword(s):  
Coefficient Of Friction ◽  
Test Procedure ◽  
Frictional Resistance ◽  
Theoretical Models ◽  
Surface Phenomenon ◽  
Vehicle Speed ◽  
Lining Material ◽  
The Coefficient Of Friction ◽  
Brake Lining ◽  
Friction Lining

Automotive brakes are the important machine element which provides an artificial frictional resistance to control the speed of an automobile. In the present work, theoretical models for the coefficient of friction between brake drum and friction liner are generated and simulated using MATLAB Simulink. A test set up designed and manufactured according to the brake lining quality test procedure (SAE J661) is used to investigate tribological properties of a non-asbestos friction lining material having 11 different constituents, which is manufactured from one of the brake liner manufacturer. An experiment is designed using response surface methodology (RSM) with vehicle speed, braking force, and sliding distance as the input parameters, whereas coefficient of friction and wear as an output. It is found that vehicle speed is the most significant parameter among the three. Fade and recovery behavior of the friction lining material is also studied and it is found that the developed friction lining material satisfies the criteria specified in SAE J661. Scanning electron microscope (SEM) and energy dispersive spectoscopy (EDS) have revealed the significant surface phenomenon.

Lubricated Friction of Rubber. III. Components of Friction in Mating Surfaces

1968 ◽  
Vol 41 (4) ◽  
pp. 854-861 ◽  
Author(s):  
E. P. Percarpio ◽  
E. M. Bevilacqua
Keyword(s):  
Laboratory Experiment ◽  
Frictional Resistance ◽  
Experimental Results ◽  
Radius Of Curvature ◽  
Critical Limit ◽  
Friction Coefficients ◽  
Resistance To Sliding ◽  
Wet Friction ◽  
Abrasive Friction ◽  
Local Pressures

Abstract Friction is usually discussed in terms of contributions from two processes: deformation and adhesion. This terminology has been retained in discussions of lubricated friction of rubber although there is not apparent any clear mechanism by which adhesion might occur. Our study of wet friction leads us to suggest that the components making up frictional resistance to sliding might more appropriately be referred to as deformation and abrasive components. On this basis, there is an obvious mechanism for both processes, and some of the disagreements about interpretation of certain experimental results may be resolved. The basis for our interpretation is implicit in the literature but was originally expressed somewhat tentatively and has not been restated in recent discussions. Greenwood and Tabor pointed out that hysteretic losses make an important contribution to friction of rubber sliding on a lubricated surface and that this contribution is independent of asperity size or distribution so long as only the asperities support the load and the radius of curvature at the asperity tip is above a critical limit which is remarkably low. Further, the experiments of Sabey showed that it was difficult to obtain coefficients higher than 0.4 with spherical sliders. Mean average local pressures high enough to give high friction coefficients could be obtained only with sharp asperities. In the laboratory experiment these were cones. Greenwood and Tabor found that with these damage to the rubber becomes visible at just the semiangle at which the coefficient began to rise abruptly (Figure 1). It is entirely reasonable to call the process causing this damage abrasive friction.

Determination of Tire-Road Friction Coefficients for Skid Mark Analysis

1985 ◽  
Vol 13 (1) ◽  
pp. 41-64
Author(s):  
W. R. Garrott ◽  
D. A. Guenther
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Friction Coefficients ◽  
Pickup Truck ◽  
The Road ◽  
Heavy Trucks ◽  
Road Friction ◽  
Brake Application ◽  
The Coefficient Of Friction

Abstract An experimental study was made to compare the validities of methods currently used by accident reconstructionists to determine the coefficient of friction between the road and the vehicle tires at the time of an incident. This value could then be used in conjunction with skid mark length and vehicle weight to calculate the prebraking speed of the vehicle. Three automobiles and three trucks with a variety of tires and loadings were used on a variety of pavements. The accuracy and area of applicability of each of four methods for obtaining friction coefficients were determined by relating the prebraking speed calculated from each to the actual speed at the time of brake application. All four methods were satisfactory for automobiles and the pickup truck used, but only two were acceptable for heavy trucks. The most valid coefficients are obtained from skid mark lengths obtained under conditions duplicating those in an incident.

XXIII.—On the Cohesion of Steel, and on the Relation between the Yield Points in Tension and in Compression.

1908 ◽  
Vol 28 ◽  
pp. 374-381 ◽  
Author(s):  
G. H. Gulliver
Keyword(s):  
Mild Steel ◽  
Yield Point ◽  
Coefficient Of Friction ◽  
External Load ◽  
Frictional Resistance ◽  
Experimental Results ◽  
Cohesive Force ◽  
Metallic Particles ◽  
Resistance To Deformation ◽  
The Coefficient Of Friction

SUMMARY(a) On the assumptions that resistance to deformation is due to simple friction, and that the coefficient of friction is independent of the load, the ratio of the yield point in tension to the yield point in compression, for what is ordinarily known as mild steel, is calculated as 2·384 to 3·384, or as 0·705 to 1. Experimental results so far obtained do not agree well with these figures, the value for the tensile yield point being relatively high, and that for compression relatively low.(b) On the further assumption that a cohesive force acting between the metallic particles gives rise to a frictional resistance which may be added (algebraically) to that due to the effect of the external load, the value of this cohesive force is deduced as equal to 3·384 times the stress which corresponds with the tension yield point, or to 2·384 times that corresponding with the compression yield point. Experimental results from a large number of tests agree very fairly with the calculated figures for the case of tension.

Metallic transfer between sliding metals: an autoradiographic study

1951 ◽  
Vol 208 (1095) ◽  
pp. 455-475 ◽  
Keyword(s):  
Coefficient Of Friction ◽  
Photographic Plate ◽  
Frictional Resistance ◽  
Autoradiographic Study ◽  
Lubricant Film ◽  
Small Range ◽  
Main Function ◽  
Boundary Lubricant ◽  
The Coefficient Of Friction ◽  
Higher Temperature

This paper describes a study of the friction and metallic transfer between sliding metal surfaces in the absence and in the presence of boundary lubricant films. One surface is made radioactive and is slid over the surface of a second, non-radioactive metal, the amount of metal transferred being detected by the blackening of a photographic plate placed in contact with the second surface. The results show that, in general, the metallic transfer or ‘pick-u p ’, consists of a relatively small number of discrete particles. For unlubricated surfaces the pick-up is about 40 times larger for similar than for dissimilar metals, although the coefficient of friction covers a relatively small range (μ ≈ 0.4 to μ ≈ 1). With well-lubricated surfaces the friction is reduced by a factor of not more than 20 (μ ≈0.05), whilst the ‘pick-u p ’ may be diminished by a factor of 20,000 or more. A simple analysis suggests that under these conditions the welded metallic junctions formed through the lubricant film play a very small part in determining the frictional resistance to motion. Consequently two lubricants possessing widely differing abilities to protect the surfaces may give essentially the same coefficient of friction. The lowest friction and ‘pick-up ’ are observed when the lubricant film is solid. As the temperature is raised a marked increase in friction and ‘pick -u p ’ occurs a t a temperature close to the melting-point of the film. A new observation is that at a somewhat higher temperature a further deterioration in lubricating properties occurs; although the surfaces are visibly covered with lubricant, the frictional behaviour and the metallic transfer are similar to those observed with unlubricated surfaces. These changes are reversible on cooling, and it is suggested that they correspond to changes in state of the lubricant film. The results provide direct support for the view that the friction between metals is due largely to the formation and shearing of metallic junctions, and that the main function of a boundary lubricant is to reduce the amount of metallic interaction. The investigation also shows that the metallic transfer is immensely more sensitive to changes in surface conditions than is the coefficient of friction.

scholarly journals Seismic Response of Pure-Friction Base Isolated Masonry Building with Restricted Base-Sliding

2007 ◽  
Vol 4 (1) ◽  
pp. 82 ◽  
Author(s):  
M. Qamaruddin ◽  
S. Ahmad
Keyword(s):  
Seismic Response ◽  
Coefficient Of Friction ◽  
Frictional Resistance ◽  
Relative Displacement ◽  
Masonry Building ◽  
Ground Acceleration ◽  
Time Period ◽  
Seismic Force ◽  
Fixed Base ◽  
Base Structure

The earthquake response of pure-friction base isolated masonry building with restricted base sliding is presented in this paper. A clear smoothened surface is created at the plinth level of the building above the damp-proof course, and the superstructure rests at this level to slide freely, except for the frictional resistance and the rigid stopper. As the superstructure is free to slide at the plinth level, there will be a feeling to the occupants that it might slide more than the permissible relative displacement limit provided at the top of the substructure. This may create a fear among the occupants that the building may overturn. In view of this, a mathematical model was developed for masonry building with restricted base sliding system using rigid stopper. Feasible position of the stopper has been determined such that the seismic response of the structure is reduced considerably in comparison with that of corresponding fixed base structure. Investigation was also made to determine the seismic response of the buildings with varying time period, mass ratio, coefficient of friction and damping coefficient subjected to Koyna and five other pseudo earthquakes. The pseudo earthquakes were generated either by increasing or decreasing the ground acceleration and duration of the Koyna accelerogram. It turns out from the present study that the pure-friction isolated restricted base sliding system is effective in reducing the seismic force acting on the masonry building with low value of coefficient of friction. 

scholarly journals Investigate the Drag Resistance of Antifouling Self-Adhesive Film

2020 ◽  
Vol 77 (2) ◽  
pp. 13-22
Author(s):  
Khor Wei-Hann ◽  
Siow Chee Loon ◽  
Adi Maimun Abdul Malik ◽  
Arifah Ali ◽  
Mohammad Nabil Jainal ◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Frictional Resistance ◽  
Percentage Increase ◽  
Ansys Fluent ◽  
Adhesive Film ◽  
Ship Model ◽  
Ship Resistance ◽  
Lack Of Information ◽  
The Coefficient Of Friction ◽  
Rotor Apparatus

Fouling has always been a common issue for ships as fouling drastically increases the surface roughness and ship resistance. The microfiber self-adhesive antifouling film is claimed to be effective up to 5 years and is environmentally friendly. However, there is lack of information about the drag characteristics of the antifouling material. Thus, this project is conducted based on an experimental study to determine the drag characteristics of the surface installed with microfiber self-adhesive antifouling film. The rotor apparatus is used to study the coefficient of friction of the microfiber surface. From the experimental results, a flat plate simulation using ANSYS-Fluent is conducted to further estimate the coefficient of friction up to Reynolds number of 109 and to evaluate the total ship resistance for the Semi-SWATH (fast vessel) and KVLCC (slow trading ships). The results show that the percentage increase in total ship resistance for the KVLCC is about 80%, which is more than the Semi-SWATH of 30%, as frictional resistance has high significance for slow trading ships. The speed drop experienced by the ship model installed with the microfiber antifouling is 2 knots for the KVLCC and 1 knot for the Semi-SWATH if the power remained the same for both models.

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%.

Measurements of Grain Kernel Friction Coefficients Using a Reciprocating-Pin Tribometer

2020 ◽  
Vol 63 (3) ◽  
pp. 675-685 ◽  
Author(s):  
Zhengpu Chen ◽  
Carl Wassgren ◽  
Kingsly Ambrose
Keyword(s):  
Coefficient Of Friction ◽  
Particle Interaction ◽  
List Type ◽  
Dynamic Friction ◽  
Friction Coefficients ◽  
Particle Level ◽  
The Coefficient Of Friction ◽  
Wall Materials ◽  
Wall Interaction ◽  
Wheat Kernels

Highlights A tribometer was used to measure the friction coefficients of corn and wheat kernels. Both static and dynamic friction coefficients were measured for particle-wall interaction. Data analysis processes were developed to calculate dynamic friction coefficients for inter-particle interaction. Abstract. Various devices have been developed to measure the coefficient of friction (COF) of grain kernels; however, the majority of these tests measure the particle-wall COF at a bulk level. A method that can accurately measure both particle-wall and inter-particle COFs at a single-particle level remains to be developed. The objective of this study was to explore the feasibility of using a reciprocating-pin tribometer to measure static and dynamic COFs between grain kernels and between grain kernels and wall materials. In this study, the methodology of the test was developed, and representative data from the particle-wall and inter-particle friction tests were reported. It was found that the static COFs of corn-steel, corn-acrylic, wheat-steel, and wheat-acrylic are 0.24 ±0.05, 0.22 ±0.03, 0.32 ±0.02, and 0.29 ±0.03, respectively. The dynamic COFs of corn-steel, corn-acrylic, corn-corn, wheat-steel, wheat-acrylic, and wheat-wheat are 0.22 ±0.06, 0.16 ±0.01, 0.09 ±0.02, 0.30 ±0.02, 0.20 ±0.02, and 0.18 ±0.04, respectively. The current study demonstrates that the reciprocating-pin tribometer is suitable for measuring the particle-wall and inter-particle COFs of grain kernels. Keywords: Coefficient of friction, Grain kernel, Reciprocating-pin tribometer

scholarly journals A Comparison of the Frictional Characteristics of Five Initial Alignment Wires and Stainless Steel Brackets at Three Bracket to Wire Angulations—an in Vitro Study

1994 ◽  
Vol 21 (1) ◽  
pp. 15-22 ◽  
Author(s):  
J. A. S. Dickson ◽  
S. P. Jones ◽  
E. H. Davies
Keyword(s):  
Stainless Steel ◽  
Coefficient Of Friction ◽  
In Vitro Study ◽  
Frictional Resistance ◽  
Vitro Study ◽  
Coated Steel ◽  
Fibre Optic ◽  
Initial Alignment ◽  
The Coefficient Of Friction

The study investigated static planar frictional resistance between five initial alignment wires and stainless steel brackets at three brackets to wire angulations (0, 5 and 10 degrees). It was demonstrated that static frictional resistance increased significantly with increasing bracket to wire angulation due to binding within the system. Epoxy-coated steel had the highest static frictional resistance and coaxial stainless steel the lowest. Fibre-optic glass (Optiflex®) had low frictional resistance. The coefficient of friction followed the trends of static frictional resistance in all respects.

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