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ICBTCAMPUS-MT
HND in Engineering
Module :Mechanical Principles
Lecturer : Mihiran Galagedara
Batch :ME_03; AU_01; MT_01
Copie :65
Date :28/03/2013
Seion :01 0f 15
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MechanicalPrinciples
~anIntroduction~
!" Mihiran GalagedaraB.Sc. Eng (Hons)UOM, AMIESL
Faculty of Engineering and
onstruction, IB! a"#us$M!,
Sri Lan%a.
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Details of the Module
Unit code: F/601/1450
QCF level: 5
Credit value: 15
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Aim
Physics
(Mechanics)
Mechanical
Principles
Engineering Design
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Learning O!c"mes
1# $e a%le !" &e!ermine !he%eha'i"ral charac!eris!ics "
materials subjected tocomplex loading systems
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Learning O!c"mes# $e a%le !" &e!ermine !he
%eha'i"ral charac!eris!ics "l"a&e& %eams an&
cylin&ers
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Learning O!c"mes
*# $e a%le !" &e!ermine !he&ynamic parame!ers "
p"+er
!ransmissi"n sys!em elemen!s
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$el! Dri'es
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Friction
Clutches
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Learning O!c"mes
4# $e a%le !" &e!ermine !he &ynamicparame!ers " r"!a!ing
sys!ems
Fly,heel
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Fly+heel " --.1
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ssessments3# Assignmen! 3
33# mma!i'eAssessmen! 01
333# Assignmen! 333# mma!i'e
Assessmen! 0
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De7ni!i"ns
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P"iss"n8s ra!i"
"nsi&er !herec!anglar %ar" s%9ec!e& !" a
!ensile l"a
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P"iss"n8s ra!i"
:n&er !he ac!i"n " !hisl"a& !he %ar +ill increase
in leng!h %y an am"n!gi'ing a l"ngi!&inal
s!rain in !he %ar ";
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P"iss"n8s ra!i" =he %ar +ill als" e>hi%i! areductionin
&imensi"ns la!erally(i.e. its breadth and depth will
both reduce) =he ass"cia!e& la!eral s!rains +ill
%"!h %e e?al; +ill %e " "pp"si!e
sense !" !he l"ngi!&inal s!rain;an& +ill %e gi'en %y
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Poissons ratio
Pr"'i&e& !he l"a& "n !hema!erial is re!aine&
+i!hin !he
elas!ic range !he ra!i" " !hela!eral
an& l"ngi!&inal s!rains +ill
al+ays %e c"ns!an!# =his ra!i" is !erme& Poissonsratio.
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P"iss"n8s ra!i" =he nega!i'e sign " !he la!eral
s!rain is n"rmally ign"re& !" lea'eP"iss"n8s ra!i" simply as
a ra!i" "
s!rain magni!&es# 3! ms! %e remem%ere&; h"+e'er;
!ha! !he l"ngi!&inal s!rain in&ces a
la!eral s!rain " "pp"si!e sign e#g# !ensile l"ngi!&inal
s!rainin&ces c"mpressi'e la!erals!rain#
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P"iss"n8s ra!i"
F"r m"s! engineering ma!erials!he 'ale " v lies %e!+een 0.25
an& 0.33. ince;
@ence
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Some Values
Material Poisson!s "atio
r%%er ~ 0#50g"l& 0#4
magnesim 0#*5
clay 0#*00#45
s!ainless s!eel 0#*00#*1
s!eel 0#B0#*0
cas! ir"n 0#10#6
san& 0#00#45
c"ncre!e 0#0
glass 0#1-0#*
c"rC ~ 0#00
a>e!ics nega!i'e
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E>ample 01
a) A 5 mm &iame!er %ar is s%9ec!e&!" an a>ial !ensile
l"a& " 100 C#:n&er !he ac!i"n " !his l"a& a #$$mm gage
leng!h is "n& !"e>!en& 0#1 x 10.* mm# De!ermine!he
m"&ls " elas!ici!y "r !he
%ar ma!erial#
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E>ample 0
%#) 3; in "r&er !" re&ce +eigh! +hils!Ceeping !he
e>!ernal &iame!erc"ns!an!; !he %ar is %"re& a>ially
!"
pr"&ce a cylin&er " ni"rm!hicCness; +ha! is !he
ma>imm&iame!er " %"re p"ssi%le gi'en !ha!
!he ma>imm all"+a%le s!ress is 40M/m =he l"a& can %e
assme& !"remain c"ns!an! a! 100 C#
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E>ample 0*
(c) ,ha! +ill %e !he change in !he"!si&e &iame!er " !he
%ar n&er!he limi!ing s!ress ?"!e& in (%) (E 210GN/m2
an& v 0#*)#
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eerences
1G $eer; F# P# an& De.,"l;H# =# (004)Mechanicsof
materials#*r&e =a!a McIra+.@ill#
G @earn; E#H# (000) Mechanics of Materials#*r&
e $@#
