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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Slider Crank Mechanism:2010-ME-206

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