Slider Crank Mechanism:2010-ME-206
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Transcript of Slider Crank Mechanism:2010-ME-206
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Dynamics Lab Report No.1
SLIDER CRANK Mechanism
Submitted by:
Syed Imtinan Ahmed
Submitted to
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Slider Crank Mechanism
Contents
1.Introduction to Slider Crank Mechanism2.Anylysis and formulating an anylytical expression3.Theoratical calculations4.Experimental data5.Comments
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MechanismMechanism is a set of resistant bodies (rigid or non rigid) interconnected to form links such that
when force is applied on one of the links ;these links interact with each other through joints to
complete the required motion or force transmission.
Mechanisms are used to convert one type of motion into another or change the direction of the
applied force.
Exapmple Of Mechanisms
Four bar Mechanism
SLIDER CRANK MECHANISM
Gear Mechanism
Chain Spocket Mechanism
Quick return mechanism
TERMS Related to Anlaysis of a Mechanisnm
There are two crutial terms that are fundamental to analysis of any Mechanism
LINKS
Kinemtaic Pairs
LINKS
These are the mechanical members that do not deform under load
during the motion.Link is not necessarily a stick like part.a link maybe composed of several parts assembled together,
and move as rigid body during motion.
KINEMATIC PAIRS
The connections present in a mechanism such that relative motion between them is consistent are
called kinematic pairs. Kinematic pairs can be classified as higher pair or lower pair
Some of the commonly used Kinematic pairs are as follows:
Four bar Mechanism
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Revolute pair
Prismatic pair or Sliding pair
Screw pair or Helical pair
Cylindrical pair or Rolling pair
Spheric pair
Planar pair
LOW Pair
.A pair is said to be a lower pairs when
the connections between two elements
are through the area of contact
Example: motion of piston in a cylinder
of an engine, motion between nut and
bolt.
HIGH PAIR
A higher pair is defined as one in which the connection between two elements has only a
point or line contact.
Example: working of gears in gears box.
ANALYSIS OF A MECHANSIM
BEFORE ANALYSIS OF ANY MECHANISM WE SHOULD ASK OURSELVES 3 FUNDAMANTAL QUSETIONS
1. How may link are in the mechanism?
2. How may joints are in the mechanism and what are their types?
3. What should be required parameters of the joints to achieve the required motion?
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SLIDER CRANK MECHANISM
Slider crank mechanism is one of the most commonly employed mechansim in
the world,it lies in the heart of every internal combustion engine.each modern
car today on the road uses this mechanism for its engine design.this
mechanism was alson foud in LEONARDO DIVINCIS drawings.it is actually
derived from the four bar mechanism
Links
1.frame -----FIXED LINK2. crank3. connecting rod4.piston
kinematic pair
A. turning pair (b/w link 1 and 2)B. turning piar(b/w link 2 and 3)---crank pinC. turning pair(b/w link 3 and 4)----wrist pinD. sliding pair (b/w link 4 and 1)
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Analysis of slider crank mechanism(SKELTON DIAGRAM)
L=length of Connecting rodR=radius of crank shaftX=distance of piston from TDC
From the skelton diagram we can say That )--------------------------------(A)We need to eliminate the angle phi from eq A for that purpose we use eq B
Y=Rsin(
)=Lcos(
)------------------------(B)
Substituting the value of cos from eq B we get
putting the value of sinin equation A we get
( )
Using binomial series we can simplify the above expression
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Analytical expression for the given apparatus in which
R=35mm and l=175mm
So linear displacement X in terms of angular displacement can be Witten as
Analytical Data
X X0 0 190 69.57
10 .637 200 68.3
20 2.5 210 66.186
30 5.56 210 63.26
40 9.6 230 59.55
50 14.556 240 55.12560 20.125 250 50.06
70 26.12 260 44.47
80 32.32 270 38.5
90 38.5 280 32.316
100 44.47 290 26.12
110 50.06 300 20.125
120 55.125 310 14.56130 59.551 320 9.63
140 63.258 330 5.56
150 66.186 340 2.52
160 68.3 350 .637
170 69.57 360 0
180 70
V=35sin+3.5(sin2)a=35cos+7(cos2)
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0
10
20
30
40
50
60
70
80
050100150200250300350400
DisplacementX
Series1
Plot of
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0
10
20
30
40
50
60
70
80
050100150200250300350400
displacemntX
Series1
Plot of and X from theoretical values
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