scholarly journals EFFECT OF CYCLE OF LOADING ON SUBBASE FRICTION CHARISARITICS UNDER RIGID PAVEMENT

2021 ◽  
Vol 25 (Special) ◽  
pp. 3-195-3-202
Author(s):  
Thulfiqar A. Aboaljus ◽  
◽  
Qais S. Banyhussan ◽  
Mohammed H. Mohammed ◽  
◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Frictional Force ◽  
Stable State ◽  
Plain Concrete ◽  
Interface State ◽  
Interface Condition ◽  
Movement Rate ◽  
The Coefficient Of Friction ◽  
Number Of Cycles ◽  
Two Stages

The coefficient of friction is a measurement of the frictional force between two objects. As the temperature of the pavement changes, it might slide against the resistance of the supporting subbase. In order for pavement to perform as anticipated, this resistance must be calculated. Concrete cracking does not occur when the pavement is joined. A membrane layer is positioned between the subbase and the plate in joint plain concrete pavements to smooth the interface. The displacement of concrete caused by temperature differences is less resistant on a smooth surface. For subbase conditions, two stages of the push-off test were performed (smooth and rough) to show the effects of movement cycles. Based on the results of the friction tests, the friction properties of the concrete and subbase were investigated. The parameters that influence the coefficient of friction and displacement are (interface state, movement rate, thickness number of movement cycles), changing the interface condition from smooth to rough leads to an increase the FRF of (6, 9 and 12 cm/hr) by (194.7, 194.4 and 189.8 %) respectively. Finally, once the applied force reaches a stable state, the frictional force increases dramatically. The most important influence on this force is the interface state, which is accompanied by movement rate and thickness. The variation of the relationship curves with number of cycles tends to be insignificant after the third to fourth cycle of slab movement.

Coefficients of Friction: Static Versus Dynamic

2020 ◽  
Author(s):  
Jack Youqin Huang
Keyword(s):  
Coefficient Of Friction ◽  
Frictional Force ◽  
Inertial Force ◽  
Static Friction ◽  
Theory And Practice ◽  
Dynamic Friction ◽  
Kinetic Friction ◽  
The Coefficient Of Friction ◽  
Static Versus Dynamic ◽  
New Discovery

Abstract This paper deals with the problem of static and dynamic (or kinetic) friction, namely the coefficients of friction for the two states. The coefficient of static friction is well known, and its theory and practice are commonly accepted by the academia and the industry. The coefficient of kinetic friction, however, has not fully been understood. The popular theory for the kinetic friction is that the coefficient of dynamic friction is smaller than the coefficient of static friction, by comparison of the forces applied in the two states. After studying the characteristics of the coefficient of friction, it is found that the comparison is not appropriate, because the inertial force was excluded. The new discovery in the paper is that coefficients of static friction and dynamic friction are identical. Wheel “locked” in wheel braking is further used to prove the conclusion. The key to cause confusions between the two coefficients of friction is the inertial force. In the measurement of the coefficient of static friction, the inertial force is initiated as soon as the testing object starts to move. Therefore, there are two forces acting against the movement of the object, the frictional force and the inertial force. But in the measurement of the coefficient of kinetic friction, no inertial force is involved because velocity must be kept constant.

Measurement of Friction between Rubber-Like Polymers and Steel

1962 ◽  
Vol 35 (2) ◽  
pp. 379-387 ◽  
Author(s):  
D. I. James
Keyword(s):  
Polymeric Material ◽  
Coefficient Of Friction ◽  
Frictional Force ◽  
Steel Plate ◽  
Dioctyl Phthalate ◽  
Direct Reading ◽  
Automatic Operation ◽  
Drive Mechanism ◽  
Flat Sheet ◽  
The Coefficient Of Friction

Abstract A machine for measuring the coefficient of friction between a flat sheet of polymeric material and a ground steel plate is described in detail. An inverted lathe cross slide forms the basis of the drive mechanism. Frictional force is balanced against the tension developed in a spring (proof ring), the extension of which measured with a commercial displacement pickup, gives a direct reading of coefficient of friction. A few results are given for a PVC sample plasticized with 40% dioctyl phthalate. A circuit for automatic operation and recording is also described.

Study of Self-Locking Mechanism of Belt Friction

2007 ◽  
Author(s):  
Keiji Imado
Keyword(s):  
Contact Angle ◽  
Coefficient Of Friction ◽  
Exponential Function ◽  
Frictional Force ◽  
Cylindrical Surface ◽  
Loading Condition ◽  
The Self ◽  
Locking Mechanism ◽  
The Coefficient Of Friction ◽  
Severe Loading

It is well know that the belt friction is expressed in an exponential function of a product μ and θ, the coefficient of friction and the angle of contact between the flexible belt and the cylindrical surface respectively. So the frictional force increases greatly with an increment of contact angle θ. Using this property, many kinds of buckles were developed to fasten belt. But the locking condition of belt is not obtained from the equation unless θ is of infinity. Their locking conditions were not clarified theoretically. In practice, the product of μθ is usually less than θ, so that the exponent of the product μθ is not so large. Then some slippage may occur in case of severe loading condition. This study is focusing on a self-locking mechanism of a simple buckle developed for flat belt. The belt in the buckle is partially wound again over the belt. According to the equation derived, the fraction of the tight side belt tension to the loose side belt tension is significantly affected by the angle of double-layered segment. With an increment of angle of doublelayered segment, the fraction increases to infinity, which means the occurrence of belt locking. The locking condition is determined by the geometry of the buckle and the coefficient of frictions. The frictional force is automatically generated by the tension of belt so that the self-locking mechanism is realized in the buckle. The equation derived was confirmed by the experiments.

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.

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.

Study on Isolation Device for Decrease of Displacement by Using Control of Friction

2007 ◽  
Author(s):  
Masanori Shintani ◽  
Naoya Taguchi
Keyword(s):  
Coefficient Of Friction ◽  
Frictional Force ◽  
Seismic Waves ◽  
Simulation Analysis ◽  
Relative Displacement ◽  
Analysis Model ◽  
Restoring Force ◽  
Seismic Isolator ◽  
Compression Spring ◽  
The Coefficient Of Friction

This paper deals with reduction of horizontal relative displacement by using a frictional force for a seismic isolator. First, a compression spring is attached to the base. Next, a slope plate is superimposed on it. The frictional force acts on the slope plate. The restoring-force is given to the seismic isolator by the compression spring attached to the base. In the equation of motion of the analytical model, the frictional force changes in proportion to the displacement. The restoring-force is also proportional to the displacement. The restoring-force always works in the direction of the center. Therefore, the frictional force and the restoring-force are both proportional to the displacement. Simulation analysis was performed under various conditions using this analysis model. As a result of conducting the analysis and an experiment with this model, it was shown that response acceleration and relative displacement can be reduced successfully. In order to reduce response acceleration and relative displacement more, analysis was carried out with the actual earthquake waves under the conditions to change the coefficient of friction by relative displacement. As a result, the coefficient of friction that reduces relative displacement most effectively without impairing the performance of the seismic isolator was established. However, the coefficient of friction that reduces the response acceleration and relative displacement effectively depends on by seismic waves. Therefore, in this report, the coefficient of friction that reduces response acceleration and relative displacement most effectively is determined by using white noise. It is analyzed with actual seismic waves by using the decided parameters. The performance of the seismic isolator is examined.

Friction between the teat and teatcup liner during milking

1973 ◽  
Vol 40 (2) ◽  
pp. 191-206 ◽  
Author(s):  
G. A. Mein ◽  
C. C. Thiel ◽  
D. R. Westgarth ◽  
Rosemary J. Fulford
Keyword(s):  
Coefficient Of Friction ◽  
Flow Rate ◽  
Frictional Force ◽  
Large Area ◽  
Elastic Solids ◽  
Milk Flow ◽  
The Coefficient Of Friction ◽  
Frictional Behaviour ◽  
Sinus Pressure

SummaryFour studies are described of the role of friction in maintaining the teatcup stable on the teat. Measurements of the coefficient of friction between teats and pieces of liners, in which most values for the coefficient fell between 0·5 and 1·0, indicated that friction between skin and rubber-like materials was consistent with the general frictional behaviour of elastic solids. Studies during milking showed that the sudden restriction of milk flow that normally occurs near the end of milking is accompanied by a marked fall in the frictional force between the teat and barrel of the open liner. During the period of peak milk flow-rate, the major source of friction maintaining the teatcup stable on the teat is the large area of contact between the teat and liner barrel. The frictional force is derived from the pressure difference across the teat wall which presses the teat against the comparatively rigid liner. Frictional force between the teat and barrel increases after the start of milking because the coefficient of friction rises as one surface gradually moulds to the other. In addition, the total frictional force increases because of the increasing area of contact whenever the teat moves deeper into the liner, until the end of the peak flow-rate period. When this period ends, friction between the teat and open barrel is reduced suddenly because the teat sinus pressure falls. After this stage, the main source of friction appears to be derived from the force between the teat and mouthpiece lip.

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.

scholarly journals THE PUSHOUT STRENGTH OF CONCRETE PAVEMENT SLAB AND CLAY SOIL LAYERS

2021 ◽  
Vol 25 (Special) ◽  
pp. 3-224-3-230
Author(s):  
Sattam D. Ghanim ◽  
◽  
Qais ѕ. Banyhussan ◽  
Thulfiqar А. Aboaljus ◽  
◽  
...  
Keyword(s):  
Concrete Slab ◽  
Stable State ◽  
Interface State ◽  
Concrete Pavement ◽  
Interface Condition ◽  
Frictional Drag ◽  
Displacement Direction ◽  
Frictional Forces ◽  
State Rate ◽  
Rate Of Movement

The frictional forces between the concrete slab and base has been combined with the movements of the horizontal slab that have been induced by variations of the moisture and temperature in concrete slabs. The frictional drag that acts on the slab bottom as a result of base friction is in an opposite horizontal slab displacement direction, and resist movements of the horizontal slab. A condition of smoother interface provides lower resistance to slab movement. On the other hand, rough interfaces are beneficial in the reduction of the load-related stresses. As bonding degree between slab and foundation affects the friction that has been mobilized at interface, a realistic evaluation of friction of the interface is required for the rational designs of the concrete pavement. In this work, push-off test has been performed. Based upon results of the friction tests, the friction characteristics of concrete and soil have been researched. The parameters that influence the maximal displacement and friction coefficient are (interface state, rate of movement) for friction and (rate of movement, interface condition) for the displacements, respectively. Finally, once the applied force reaches a stable state, the frictional force increases dramatically. The most important influence on this force is the interface state, which is accompanied by movement rate. The change of the interface from a smooth to a rough surface increases the overall coefficient of friction.

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