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TribologyinMechanicalEngineering
MAE493N/593T
Dr.Konstantinos
A.
Sierros
WestVirginiaUniversity
Mechanical&AerospaceEngineering
ESBAnnex263
[email protected]
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EngineeringTribology
JohnWilliams
Cambridge
Tribology:Friction
&
Wear
ofEngineeringMaterials
IanHutchings,Elsevier
Books
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Syllabus
Pleaseseehandout
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Guidelines
Grading
GroupProject
30%
ShortLabReport 20%
MidtermExam 25%
FinalExam
25%
Inmostcases,attendingclasshelpsunderstandingthesubject
Theaimistoformworkinggroupsthatcaninteractwitheachother
Discussionbasedinteraction
Projectbased
learning
Introductiontoresearchmethods
Understand thefundamentalsof
tribologyinamechanicalengineeringcontext
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Courseoutline
Introduction
Surfaces
Contactbetweensurfaces
Friction
Wearandwearmechanisms
Lubricantsandlubrication
Bearings Nanotribology
Biotribology
Tribocorrosion Tribotronics
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Topics
Historyoftribology
Bearingmaterials
Lubricants TribologyLiterature
1.
Introduction
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1.Introduction
Theword
tribology
comes
from
the
combined
Greek
word;
tribology
Professor
H.
Peter
Jost
gave
birth
to
the
word
tribology in
1966 Theconceptcouldbealsocalledtriboscienceand
tribotechnology
Jostreport(1966)
Landmarkinthedevelopmentofthesubject
1/3of
our
global
energy
is
consumed
wastefully
in
friction!
rubbing study
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Definitionoftribology
Tribologyis
the
science
and
technology
of
interacting
surfaces
in
relativemotion
Tribology
Wear Friction Lubrication
Wear
Damagetooneorbothsurfacesinvolving,inmostcases,
progressivelossofmaterial
Friction
ResistanceencounteredbyonebodyinmovingoveranotherLubrication
Actiontoreducefrictionalforcebetweensurfacesby
usinglubricants
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Historyoftribology
5000yearsago
Mesopotamia
Wheeledcarriages
were
used
Bearing
development
4000yearsago
TransportofanEgyptianstonecolossus
Lubrication
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Historyoftribology
China
2400
years
ago
Development
of
lubricated
bronze
bearings
for
use
in
warchariots
Greece2000yearsago Designofpivots,bearingsformechanical
devices
Thelathe
was
developed
2000
years
ago
MarcusVitruviusPolio RomanArchitect&Engineer
Developedalot
oftribologicalideas
He worked on the ballista development
..and more
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Historyoftribology
RomanEmpire Rollingelementbearingsusedtosupportwoodenplatforms
MiddleAges(AnnoDomini400
1450)
ChinawasleadingthetechnologicalraceandEuropewasfollowing
MiddleAges
Animal
fats
were
used
as
Lubricants
LeonardodaVinci(AnnoDomini1452
1519)
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Historyoftribology
Allthingsandeverythingwhatsoeverhoweverthinitbewhichis
interposedinthemiddlebetweenobjectsthatrubtogetherlightenthedifficultyoftheirfriction
LeonardodaVinci
Wearof
iron
axles
and
wooden
shafts
Woodiswearingandproducesdebrisparticlesthatweartheharderironsurface
i.e.Threebodyabrasivewear
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Historyoftribology
http://www.tribology.group.shef.ac.uk/teaching/about_leonardo.html
Hisnotebookswerekeptinaprivatecollectionfor200years(!)inhibiting
therapiddevelopmentofthesubjectatthatstage
http://www.tribology.group.shef.ac.uk/teaching/about_leonardo.htmlhttp://www.tribology.group.shef.ac.uk/teaching/about_leonardo.html
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Historyoftribology
15th
Century Bearingsstarttoemploymetals(ratherthanwoodand
stone)
15th
Century
Rollingelementbearingswereintroducedinlargescale
machinery
Middlepartof17th
Century
AgeofReason
Developmentof
Scientific
Method
RoyalSociety(England),AcademieRoyaledesSciences(France)were
created
by the end of 17th
Century the
Laws of Friction were stated and we
still use them!
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Historyoftribology
IsaacNewton(16421727)
Setkeystonesinfluidmechanicsandthus
LubricationTheory
150yearslater,ClaudeNavierdefined
thecoefficientofviscosityinfluidmotion
equations
Lubrication
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Historyoftribology
LeonhardEuler(17071783)
Firstmathematical
approach
to
tribology
Staticanddynamic/kineticfriction(s,k)
http://upload.wikimedia.org/wikipedia/commons/7/7d/Free_Body_Diagram.png
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Historyoftribology
18th
Century
Industrialrevolutionstarts
Bearingsand
tribological
elements
of
machines
Brassonsteel,developmentofspecialbearingalloysbasedonSn
CharlesCoulomb(1785)
Effectof
load
and
area
on
frictional
resistance
for
arange
of
material
combinations
Mechanical interlocking of asperities
Friction Adhesion + Deformation
Coulomb friction
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Historyoftribology
18th
Century
Nikolai
Petrov
(1883)
Railwayfrictionandlubricanteffects
Frictionalforceisproportionaltobearingarea,slidingspeed,
lubricantvelocity
BeauchampTower(1885)
Frictionathighvelocities
Conceptofhydrodynamiclubricationwasborn
OsborneReynolds(1886) Theoreticalanalysisoflubricated
bearings(RoyalSociety)
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Historyoftribology
HeinrichHertz(1882) Analysisofdrycontactofsurfaces
Contactstressesanddeformationbetweenelasticsolids
Initiationofgasandvapourlubricationfields
Sommerfield,Michell,
Lord
Rayleigh,
Kingsbury
Late19th
Century Evolutionofbicycledesign(Ball
bearingsforbicyclehubs,steeringheadsetc)
Early20th
Century
Effectsofstiffnessandstabilityof
bearings
SirWilliamHardy(1922)
Introductionofboundary
lubricationterm
i f ib l
http://upload.wikimedia.org/wikipedia/commons/1/18/Kontakt_Spannungsoptik.JPG
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Historyoftribology
PhilipBowden(1950)CavendishLab
DavidTabor(1964)CavendishLab
Bothworkedonfundamentalmechanismsof
friction
ProfessorH.PeterJostgavebirthtothewordtribology
in1966
Theconceptcouldbealsocalledtriboscienceand
tribotechnology
Jostreport(1966)
Landmarkinthedevelopmentofthesubject
l
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currently
Researchismovingtosmallerscales
Weneedtounderstandindividual
tribologicalevents
at
small
scales
http://www.chem.tamu.edu/rgroup/batteas/research.html
B i
http://www.chem.tamu.edu/rgroup/batteas/research.htmlhttp://www.chem.tamu.edu/rgroup/batteas/research.html
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Bearings
Practicallyalltribosystemsinvolvebearingsofsomesortor
another
Bearing:Adevicewhichpermits2componentsina
mechanismtomoverelativetooneanotherineither1Dor
2Dwhile
constraining
their
movement
in
the
remaining
dimensions
Bearings
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Bearings
Bearings
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Bearings
elastomeric
block
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Bearingmaterials
Bearingmaterials
must
withstand
external
loads
without
undergoingdimensionalchanges
Mechanismsthatleadtobearingmaterialfailureinclude;
o Materialfatigueontheloadbearingsurface
o Corrosion
o Bearingoverload
o Failureoflubricantsupply
o Abrasivewearbycontamination
o Subsurfacematerial
imperfections
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Hardness
Hardnessmeasureshowstrong
thematerialis
Hardness
istheresistanceofthesurfaceofamaterialtodeformpermanently
whenpressedbyahardasperity
Lubricants
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Tillthemiddleofthe19th
Centuryanimalfatswereused
Then,duetooildrilling,mineraloilsbecameavailable
Wecan
get
mineral
oils
from
the
distillation
of
crude
petroleum
Mineraloilsaremostlymadeupfromhydrocarbons(CandHcompounds)
Hydrocarbonscanbeparaffinic,naphthenic,aromatic
Noringstructures
Ringstructures,
single
bonds
Ringstructures,
Single&doublebonds Muchsmallerquantities
thantheabove
Viscosity
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Extremelyimportantinlubricationscience
Thedynamicorabsoluteviscosity(n)
ofafluidisameasureoftheresistanceitoffers
Torelative
shearing
motion
.
=n
shearstress
(shearforce/unitarea)
shearstrain
rate,
velocity
gradient
shearingforce
betweentwo
plates
Viscosity
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Viscosity
(shear
stress)/(velocity
gradient)Pas
Nsm2
Kgm1
s1
kinematicviscosity=(absoluteviscosity)/(density)
Fluidpropertywhereflowisduetoselfweightorgravity
Tribology literature
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Tribologyliterature
Widevarietyofbooks,handbooksandjournalsfortribology
Somearegiveninpages36and37(WilliamsCh.1)
Itmay
be
beneficial
to
spare
acouple
of
minutes
to
go
through
the
list.
