scholarly journals Characteristics of a Tire Friction and Performances of a Braking in a High Speed Driving

2014 ◽  
Vol 6 ◽  
pp. 260428 ◽  
Author(s):  
Yumrak Oh ◽  
Hoguen Lee
Keyword(s):  
Coefficient Of Friction ◽  
High Speed ◽  
Skid Resistance ◽  
Conservation Of Energy ◽  
Driving Speed ◽  
The Coefficient Of Friction ◽  
Braking Distance ◽  
The Difference ◽  
Tire Friction ◽  
Safe Road

The goal of pavement is to deliver the fine roughness and the safe road surface to traffic. It requires a secured and comfortable surface using the controlled speed of road. Through adjusting driving speed, skid resistance can be altered in one of the performances of the pavement surface. In high speed driving, there might be a certain level of risk, not in the same level as the proposed roads. Hence, this study first analyzes the speed equation under a consideration of a braking distance and then suggests the friction coefficient in high speed driving with the principle of conservation of energy. If we accept simply that the coefficient of friction is independent of speed, the difference between analysis and test value for braking distance is greatly generated. Therefore we have to analyze the coefficient of friction as an exponential function of braking speed of a vehicle.

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. 

Angular Parameter for Characterizing Road Surface Microtexture

2000 ◽  
Vol 1723 (1) ◽  
pp. 66-72 ◽  
Author(s):  
Minh-Tan Do ◽  
Hassan Zahouani ◽  
Roberto Vargiolu
Keyword(s):  
Profile Analysis ◽  
Road Surface ◽  
Skid Resistance ◽  
Analysis Program ◽  
Simple Method ◽  
Coarse Aggregates ◽  
The Difference ◽  
Tire Friction ◽  
Tactile System

Development of a device for measuring road surface microtexture and the determination of a microtexture parameter related to wet road/tire friction are discussed. A laser autofocus system was selected from existing devices. The required characteristics were defined from consideration of the contact between wet roads and tires. The autofocus principle is presented briefly, and comparison is made with a tactile system. The microtexture parameter, called the theta parameter, is defined from the useful parts of the texture profiles, that is, those in contact with the tire. It characterizes relative positions of profile peaks. A simple method was proposed to define the peaks. The profile analysis program is presented briefly. Relevance of the theta parameter was validated on surfaces composed of coarse aggregates with planar exposed faces. The specimens were polished using a projection method to emphasize the microtexture contrast between surfaces. Friction was measured using a skid resistance tester (SRT) pendulum. Profiles were measured using both laser and tactile systems. Characteristics of profiles are given. The statistical distribution of theta values obtained on a profile may be described by an exponential function. Close agreement was found between theta values obtained from laser and tactile profiles, values from laser profiles being somewhat lower. The difference is attributed to profile length. Fair correlation was found ( r2 > 0.80) between theta values and SRT friction, and similar tendencies were observed from laser and tactile data.

Formation of a High-speed Mode of Vibration Displacement of Grain During Heat Treatment

2020 ◽  
pp. 88-96
Author(s):  
Roman Kalinichenko ◽  
◽  
Serhii Stepanenko ◽  
Boris Kotov ◽  
◽  
...  
Keyword(s):  
Heat Treatment ◽  
Differential Equations ◽  
Coefficient Of Friction ◽  
High Speed ◽  
Air Flow ◽  
Support Surface ◽  
System Of Differential Equations ◽  
Vibration Displacement ◽  
The Coefficient Of Friction ◽  
Speed Mode

The article compiled and solved a system of differential equations of motion of a material point along a porous (air-permeable) surface, which is inclined at an angle to the horizon. Based on the analysis of solutions to this system of differential equations, it is proposed to change the speed of grain movement by the frequency of oscillations of the support surface, the angle of inclination of the support surface to the horizon and the coefficient of friction. Also, the graphical dependences of the speed of grain movement on the angle of inclination of the support surface to the horizon, the coefficient of friction and the frequency of oscillations were obtained. The possibility of decelerating the vibration movement of grain by an air flow, which is fed from the bottom of the porous support surface against (at an angle) the direction of grain movement, as well as using an asymmetrically corrugated support surface with vertical perforations, is theoretically substantiated. A linear regression dependence of the change in the vibration displacement speed has been experimentally determined, which makes it possible to form the required speed mode of vibration displacement of grain by changing the parameters: the inclination of the vibrating plane is 50 ÷ 90, the vibration frequency is 45 ÷ 55 s-1, the air flow speed is 0.1 ÷ 2 m/s in optimal operating modes. installations for high-intensity heat treatment of grain with a vibratory conveyor.

Sliding in rough convex bowls

2014 ◽  
Vol 98 (541) ◽  
pp. 8-23
Author(s):  
Mark Hennings ◽  
Jon Ingram
Keyword(s):  
Coefficient Of Friction ◽  
Initial Speed ◽  
Interior Surface ◽  
Starting Point ◽  
The Coefficient Of Friction ◽  
Braking Distance ◽  
Image Position ◽  
Elementary Fact

It is an elementary fact that a particle sliding on a rough horizontal table experiences a deceleration of magnitude μg, where μ is the coefficient of friction between the particle and the table. Thus, if the initial speed u of the particle and the braking distance d are both known, then μ can be determined by the formulaThe idea of using braking distances to determine the coefficient of friction led the second author to ask the following question:A particle slides on the interior surface of a rough hemispherical bowl starting from rest. If the starting point of the particle and the point at which it comes to instantaneous rest after its slide are both known, is it possible to determine the coefficient of friction between the particle and the bowl?

Effect of surface structure, composition and texture on friction under boundary conditions

1952 ◽  
Vol 212 (1111) ◽  
pp. 508-512
Keyword(s):  
Oxide Film ◽  
Boundary Conditions ◽  
Coefficient Of Friction ◽  
Substrate Material ◽  
Pure Aluminium ◽  
Surface Layers ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
Frictional Behaviour ◽  
Effect Of Surface

The coefficient of friction of surfaces lubricated under boundary conditions may be profoundly affected by such factors as the degree of working of the substrate material, the nature of the oxide film and the degree of roughness of the surface. Experiments are described wherein the frictional behaviour of surfaces of stainless steel specimens prepared in various ways was compared. The worked surface layers in these particular experiments appear to increase the value of the coefficient of friction, but the effect of surface texture is of predominant importance. The effect of different oxide films is best illustrated by reference to pure aluminium, the surface of which has been oxidized under different environmental conditions. The constitution of the oxide film formed is modified with a consequent effect on boundary friction. When the friction of rough and smooth surfaces is compared, the difference in behaviour appears to be qualitative rather than quantitative.

Fine Motor Control with CBR Protective Gloves

1987 ◽  
Vol 31 (11) ◽  
pp. 1206-1210 ◽  
Author(s):  
Demetrios Karis
Keyword(s):  
Motor Control ◽  
Coefficient Of Friction ◽  
Ring Finger ◽  
Fine Motor ◽  
Control Task ◽  
Trial Time ◽  
Cursor Control ◽  
The Coefficient Of Friction ◽  
Within Subjects ◽  
The Difference

Using a within-subjects design, performance on a continuous cursor control task was measured in three conditions: no gloves, flight gloves, and a combination of three gloves worn simultaneously for chemical, biological, or radiological (CBR) protection. Twelve subjects used their left ring finger on a two-axis force controller to move a cursor on a CRT. After centering it over one of eight possible targets, they depressed the controller to designate the target and end a trial. Time to acquire the target and accuracy in centering the cursor over the target were recorded. Subjects had faster acquisition times in the two glove conditions with no increase in errors, although only the difference between the CBR gloves and no-gloves was statistically significant. My explanation for these findings is that the thickness of the gloves may have improved the fit of the fingertip in the force controller, which was concave, and also prevented the finger from slipping by increasing the coefficient of friction between the finger and the controller.

Tribological properties of pyrolytic carbon in high-speed tests

2020 ◽  
pp. 71-75
Author(s):  
V. A. Khorev ◽  
V. I. Rumyantsev ◽  
G. A. Ponomarenko ◽  
A. S. Osmakov ◽  
V. N. Fischev
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
High Speed ◽  
Tribological Behavior ◽  
Pyrolytic Carbon ◽  
Extreme Conditions ◽  
Friction Units ◽  
The Difference

The friction units of modern power turbines require the use of special materials with a stable and low coefficient of friction in extreme conditions. The most successfully used for these purposes are antifriction carbon-graphite materials, in particular isotropic pyrolytic carbon. It is established that isotropic pyrolytic carbon has a lower friction coefficient and wear rate than ATG-S antifriction graphite. Based on the analysis of the microstructure and fractograms of wear traces, it was suggested that the difference in the tribological behavior of materials is caused by various mechanisms of material destruction. It is also shown that isotropic pyrolytic carbon tends to decrease the wear rate and friction coefficient with increasing density. Ill. 7. Ref. 10. Tab. 1.

scholarly journals An error analysis of the techniques used in the measurement of high-speed friction on snow

1994 ◽  
Vol 19 ◽  
pp. 19-24
Author(s):  
S. C. Colbeck
Keyword(s):  
Error Analysis ◽  
Coefficient Of Friction ◽  
Frictional Force ◽  
High Speed ◽  
Reading Speed ◽  
Air Drag ◽  
Speed Sensor ◽  
The Coefficient Of Friction

Controlled tests are needed to find the coefficient of friction of snow as a function of speed. An error analysis shows how the test must be designed to give accurate answers. It seems necessary to use a remotely controlled, aerodynamical sled in place of a skier to get accurate results. Otherwise, two sets of tests are necessary, one to determine air drag versus speed and one to determine the frictional force versus speed, and even these tests would probably not give satisfactory results. The slope used for testing should be sleep for a quick acceleration and then uniform, but not flat, where the actual measurements are taken. A continuously reading speed sensor is needed, not discrete measuring points. Even with the underlying principles understood, there will still be many practical problems to be solved before accurate results can be obtained.

Frictional Study of a High-Speed Helical Gear Pair Using Computational and Experimental Thermo-Elastic Analyses

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Jiří Dobiáš ◽  
Jan Hrubý ◽  
Jozef Kordík ◽  
Svatopluk Pták ◽  
Jan Masák ◽  
...  
Keyword(s):  
Heat Flux ◽  
Coefficient Of Friction ◽  
High Speed ◽  
Helical Gear ◽  
Temperature Fields ◽  
Stress Fields ◽  
Frictional Heat ◽  
Gear Pair ◽  
The Coefficient Of Friction ◽  
Helical Gear Pair

Abstract The paper is concerned with frictional study of a high-speed lubricated helical gear pair. The objectives were numerical evaluations of temperature and stress fields of the gear pair and the analysis of their frictional interaction in terms of the coefficient of friction. The problem was also investigated experimentally by temperature measurements at several points of a tooth. We developed an algorithm of numerical modeling based on an iterative scheme generating a sequence of approximate solutions to the temperature and stress fields till attainment of convergence of the numerically obtained and measured temperatures. Since the coefficient of friction significantly affected the frictional heat flux and thereby the temperature fields, it was used as a calibration parameter of the numerical model. Its magnitude was updated from an initial value until the one the process reached convergence with. The outcomes of the study include the temperature and stress fields, the magnitude of the coefficient of friction, and the frictional heat flux distribution.

Friction Characteristics of Porous Rubber Under Wet Conditions

2009 ◽  
Author(s):  
Yutaro Kosugi ◽  
Tomoaki Iwai ◽  
Yutaka Shokaku ◽  
Naoya Amino
Keyword(s):  
Friction Force ◽  
Coefficient Of Friction ◽  
Contact Surface ◽  
Road Surface ◽  
Water Removal ◽  
The Road ◽  
Rubber Specimen ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
Tread Rubber

In recent years, porous rubber has been used as a tread matrix for studless tires. It is said that the pores in the tread rubber remove water between the tire and the wet road surface; however, the water removal is not sufficiently well understood. In this study, a rotating rubber specimen was rubbed against a mating prism to observe the contact surface. The friction force was also measured simultaneously with observation of contact surface. The water entering the pores was distinguished by the continuity method. As the result of these experiments, the coefficient of friction for rubber having pores on the surface was found to be larger than that of rubber without pores. Moreover, the difference in the coefficient of friction for rubber specimens with and without pores tended to be larger at lower sliding speeds. No water entered pores 3mm or less in diameter at any sliding speed in this experiment. An experiment to make the rubber specimen collide with the mating prism was conducted since actual tires seem to be deformed by the vehicle weight, such that the tire surface might contact the road collisionally. In the resulting collision experiment, the water did enter pores 3mm in diameter.

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