This document discusses the laws of dry friction and coefficients of friction. It explains that when a horizontal force is applied to a block on a surface, a static friction force develops to counter the force and keep the block in equilibrium until the force reaches the maximum static friction limit. It also describes how angles of friction can be used and provides examples of problems involving dry friction, such as determining if a block will remain at rest or slide down an inclined plane.
It is power point presentation on belt and chain drive. you can find working and mechanism of chain and belt drive and their advantage and disadvantages.....enjoy.
Whirling of shafts occurs due to rotational imbalance of a shaft, even in the absence of external loads, which causes resonance to occur at certain speeds, known as critical speeds.
The two elastic constants are usually expressed as the Young's modulus E and the Poisson's ratio n. However, the alternative elastic constants K (bulk modulus) and/or G (shear modulus) can also be used. For isotropic materials, G and K can be found from E and n by a set of equations, and vice-versa.
It is power point presentation on belt and chain drive. you can find working and mechanism of chain and belt drive and their advantage and disadvantages.....enjoy.
Whirling of shafts occurs due to rotational imbalance of a shaft, even in the absence of external loads, which causes resonance to occur at certain speeds, known as critical speeds.
The two elastic constants are usually expressed as the Young's modulus E and the Poisson's ratio n. However, the alternative elastic constants K (bulk modulus) and/or G (shear modulus) can also be used. For isotropic materials, G and K can be found from E and n by a set of equations, and vice-versa.
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Friction. Do you know what is friction and how it plays different roles in our general life. There are many section in our life where friction is necessary like - in playing sitar and guitar, walking on the road and to hold something in our hand or in any mechanical devices. But there are many field where friction is not required like - in machines where two surfaces meet at a point. Due to this the life of the machine parts get decreased and failure may be occur there. Know more about different laws of friction, types of friction, elimination of the friction.
Ekeeda Provides Online Video Lectures for Civil Engineering Degree Subject Courses for All Engineering Universities. Visit us: https://ekeeda.com/streamdetails/stream/civil-engineering
Friction. Do you know what is friction and how it plays different roles in our general life. There are many section in our life where friction is necessary like - in playing sitar and guitar, walking on the road and to hold something in our hand or in any mechanical devices. But there are many field where friction is not required like - in machines where two surfaces meet at a point. Due to this the life of the machine parts get decreased and failure may be occur there. Know more about different laws of friction, types of friction, elimination of the friction.
Teaching bridge basics to high school teachers for implementing more engineering curriculum in their classes. This was followed up with many hands on and digital bridge building exercises. Made for the http://www.dyfference.org program.
Unit 3- friction and belt drives, Dynamics of machines of VTU Syllabus prepared by Hareesha N Gowda, Asst. Prof, Dayananda Sagar College of Engg, Blore. Please write to hareeshang@gmail.com for suggestions and criticisms.
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Learn Online Courses of Subject Engineering Mechanics of First Year Engineering. Clear the Concepts of Engineering Mechanics Through Video Lectures and PDF Notes. Visit us: https://ekeeda.com/streamdetails/subject/Engineering-Mechanics
Whenever a body is subjected to an axial tension or compression, a direct stress comes into play at every section of body. We also know that whenever a body is subjected to a bending moment a bending moment a bending stress comes into play.
1. Engineering Mechanics: Statics
The Laws of Dry Friction. Coefficients of Friction
• Block of weight W placed on horizontal
surface. Forces acting on block are its weight
and reaction of surface N.
• Small horizontal force P applied to block. For
block to remain stationary, in equilibrium, a
horizontal component F of the surface reaction
is required. F is a static-friction force.
. 8 - 1
is required. F is a static-friction force.
• As P increases, the static-friction force F
increases as well until it reaches a maximum
value Fm.
NF sm µ=
• Further increase in P causes the block to begin
to move as F drops to a smaller kinetic-friction
force Fk.
NF kk µ=
2. Engineering Mechanics: Statics
The Laws of Dry Friction. Coefficients of Friction
• Four situations can occur when a rigid body is in contact with
a horizontal surface:
. 8 - 2
• No friction,
(Px = 0)
• No motion,
(Px < Fm)
• Motion impending,
(Px = Fm)
• Motion,
(Px > Fm)
3. Engineering Mechanics: Statics
Angles of Friction
• It is sometimes convenient to replace normal force
N and friction force F by their resultant R:
. 8 - 3
• No friction • Motion impending• No motion
ss
sm
s
N
N
N
F
µφ
µ
φ
=
==
tan
tan
• Motion
kk
kk
k
N
N
N
F
µφ
µ
φ
=
==
tan
tan
4. Engineering Mechanics: Statics
Angles of Friction
• Consider block of weight W resting on board with
variable inclination angle θ.
. 8 - 4
• No friction • No motion • Motion
impending
• Motion
5. Engineering Mechanics: Statics
Problems Involving Dry Friction
. 8 - 5
• All applied forces known
• Coefficient of static friction
is known
• Determine whether body
will remain at rest or slide
• All applied forces known
• Motion is impending
• Determine value of coefficient
of static friction.
• Coefficient of static
friction is known
• Motion is impending
• Determine magnitude or
direction of one of the
applied forces
6. Engineering Mechanics: Statics
Sample Problem
SOLUTION:
• Determine values of friction force
and normal reaction force from plane
required to maintain equilibrium.
• Calculate maximum friction force
and compare with friction force
required for equilibrium. If it is
greater, block will not slide.
. 8 - 6
A 100 lb force acts as shown on a 300 lb
block placed on an inclined plane. The
coefficients of friction between the block
and plane are µs = 0.25 and µk = 0.20.
Determine whether the block is in
equilibrium and find the value of the
friction force.
greater, block will not slide.
• If maximum friction force is less
than friction force required for
equilibrium, block will slide.
Calculate kinetic-friction force.
7. Engineering Mechanics: Statics
Sample Problem
SOLUTION:
• Determine values of friction force and normal
reaction force from plane required to maintain
equilibrium.
:0=∑ xF ( ) 0lb300-lb100 5
3 =− F
lb80−=F
:0=∑F ( ) 0lb300- 4 =N
. 8 - 7
:0=∑ yF ( ) 0lb300- 5
4 =N
lb240=N
• Calculate maximum friction force and compare
with friction force required for equilibrium. If it is
greater, block will not slide.
( ) lb48lb24025.0 === msm FNF µ
The block will slide down the plane.
8. Engineering Mechanics: Statics
Sample Problem
• If maximum friction force is less than friction
force required for equilibrium, block will slide.
Calculate kinetic-friction force.
( )lb24020.0=
== NFF kkactual µ
lb48=actualF
. 8 - 8