Material Selection Lecture

7/17/2019 Material Selection Lecture

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BMFB 3323Materials SelectionSEM II 2010/2011

BMFB 3323 SEM II 2014/2015 Lecture 2 THE DESIGN PROCESS THEB!SIC

Lecture 2

Materials Selection:THE DESIGN PROCESS & THE BASIC



• Materials Attributes:

e.g. Mechanical, thermal, electrical, !tical an" chemical

!r!ertie#, c#t an" a$aila%ilit&, !rce##ing characteri#tic# an" theen$irnmental cn#e'uence# ( it# u#e.

e.g. )en#it&, #trength, , re#i#tance t crr#in.

• Process Attributes :

e.g. *he material# it can han"le, the #ha!e it can ma+e, their #ie,!reci#in an" the ecnmic %atch #ie -the num%er ( unit# that it an

ma+e m#t ecnmicall&.

REF"ECTION#



To develop a strategy for selecting materials and

process that is design-led.

Using translation, screening, ranking and documentation

as a tool in selection strategy

"E!RNING O$TCOMES



• “)e#ign i# the !rce## ( tran#lating a ne i"ea r a mar+e" nee"

int "etaile" in(rmatin (rm hich a !r"uct can %e ma"e -M.F.

#h%&

• Engineering "e#ign i# the !rce## ( "e$i#ing a #&#tem,

cm!nent, r !rce## t meet "e#ire" nee"#.

• *he "e#ign !rce## cn#i#t# ( #e$eral #te!#, each ha# certain

characteri#tic# an" certain ta#+# t %e !er(rme":

ecgni#ing a nee" -!r%lem

)e(ining the !r%lem

E#ta%li#hing #!eci(icatin#

athering in(rmatin

INTROD$CTION



THE DESIGN PROCESS

A systematic problem solving strategy, with criteria and

constraints, used to develop many possible solutions to

solve a problem or satisfy human needs and to narrowdown the possible solutions to one final choice



TPES O! DESIGN

• New idea working principle !fromscratch"Original design

• #mprovements of e$isting product• e.g% &ars, consumer products !mobile

phones, cameras etc'"

Adaptive/Development

Design

• &hange in scale or dimensions withoutchanging the function

• e.g% desktop (& to laptop computerVariant Design



THE DESIGN !LO" CHART



THE DESIGN F"O% CH!RT



MATERIALS DATA IN THE DESIGNPROCESS



MATERIALS DATA IN THE DESIGNPROCESS

The design process may notseem as logical ) linear as it is.

The design process is completeonly when a compatible pathfrom “need* to “specification*can be identified.

The key + /#0##T1.

&2s3 &oncepts

2s3 mbodiments of &2s

42s3 4etailed reali5ations of 2s



Metals

Ceramics

MATERIALSComposites

Polymers

lat ! S"eetS#APES

Prismatic

$%D

Casting

Mo&lding

PROCESSESPo'der Met"ods

Mac"ining

At each stage of thedesign, decisions needto be made aboutwhat to make it out of(Materials),and how to make it(Processes and

S"apes)



*) Concept&al

4esign proceed by developing concepts to

perform the function

At this stage, all options are open

The designer considers alternatives concepts

and ways

THE DESIGN PROCESS



+) Em,odiment

Take the promising concepts and seeks to analy5e their

operation at an appro$imate level.

#nvolves selecting materials, si5ing components,

e$amining the implications for performance and cost.

The embodiment stage ends with a feasible layout

Then passed to the detailed design stage

THE DESIGN PROCESS



$) Detail

6pecifications for each component are drawn up.

7ptimi5ation methods are applied to ma$imi5e

performance.

inal choice of material and process are made

THE DESIGN PROCESS



• #teration, looping back to e$plorealternatives, is an essential part of thedesign process.

• Think of each of the many possible

choices that could be made as an arrayof blobs in design space as suggested inthe fig.

• Then the design process becomes one ofcreating paths, linking compatible blobs,until a connection is made from the top!88market need22" to the bottom!88product specification22".

• 7nce a path is found, it is alwayspossible to make it look linear andlogical process.

• Thus a key part of design, and ofselecting materials for it, is flexibility, the ability to explore alternatives

quickly.



DESIGN TOO"S !ND M!TERI!"SD!T!



!#NCTION$ MATERIAL$SHAPE$ AND PROCESS

unction dictates the choice of bothmaterial and shape.

(rocess is influenced by the material3 byits formability, machinability, weldability,heat-treatability, and so on.

(rocess obviously interacts with shape9the process determines the shape, thesi5e, the precision and the cost.

The interactions are two-way3:.6pecification of shape restricts the choice

of material and process

;.6pecification of process limits thematerials you can use and the shapes they

can take

Functin, material, #ha!e an"

!rce## interact.



E%a'le o( )esi*n 'rocess+,,Nee) - Conce't - E.o)ient

ConceptsNeed

Embodiments

Direct pull Levered pull Spring assisted pull Geared pull

"e$ice i#

re'uire" t all

acce## t ine in

a cr+e" %ttle



Detail

E.o)ient -Detail

Embodiment



S&mmary

The key part of design and of selecting materials is

fle$ibility, the ability to e$plore alternatives <uickly

=eeping the big picture as well as the details in focus.

THE DESIGN PROCESS



CASE ST#D :/, Coolin* 'o0er electronic

>icrochips, particularly those for power electronics,get hot. #f they get too hot, they cease to function.

?hat is the need@

A scheme for removing heat frompower microchips.



6tep :34evise concepts to meet the need.

To remove heatfrom power

microchips




To remove heatfrom powermicrochips

&:3 &onduction

&;3 &onvection

&3 vaporation

&B3 Cadiation

Concept




6tep ;36ketch an embodiment of all of them.

To remove heatfrom power

microchips

&:3 &onduction

&;3 &onvection

&3 vaporation

&B3 Cadiation




To removeheat from

powermicrochips

&:3&onduction

>assive, with sufficient heat capacity to absorbheat over work cycle

&ompact, re<uiring back-up by coupling toconvection, evaporation or radiation

&;3&onvection

ree convection not re<uiring fan or pump

orced convection with fan or pump

&3vaporation

Unconfined, such as a continuous spray ofvolatile fluid

&onfined, utilising heat-pipe technology

&B3Cadiation

Cadiation to ambient, using high emissivitycoatings

Cadiation to cooled surface, from high emissivity

surface to highly absorbent surface

Concept Embodiment




ist three things that you are very clearof.

ist three things that you feel ha5y about.

ist three things that you need further

clarification.

THE DESIGN PROCESS



BMFB 3323Materials SelectionSEM II 2010/2011

BMFB 3323 SEM II 2014/2015 Lecture 3 THE B!SIC

Lecture 1

Materials Selection:THE BASIC



6election involves seeking the best matchbetween the property-profiles of the materialsand that re<uired by the design.

The selection task involves3

a" #dentifying the desired attribute profile and then

b" &omparing it with those of real engineering

materials to find the best match.

THE B!SICS OF M!TERI!"SSE"ECTION




M!TERI!"S SE"ECTION



All Materials

Translate Design re-&irements

Screen &sing constraints

Ran. &sing o,ective

See. s&pporting in0ormation

inal MaterialC"oice

M!TERI!"S SE"ECTIONSTR!TEG&



The selection strategy

• ?hat does component do@unction

• ?hat non-negotiable conditions must be

met@• #s an essential condition that must be met,

usually e$pressed as a limit on a material orprocess attribute.

&onstraints

• ?hat is to be ma$imi5ed or minimi5ed@• #s a <uantity for which an e$treme value !a

ma$imum or minimum" is sought, fre<uentlycost, mass or volume.

7bDective

• ?hat parameters of the problem is thedesigner free to change.ree Eariable



1) Translation

• Converting the design requirements into a prescription for

selecting a material and a process to shape it.

• Any engineering component has one or more functions,

subject to constraints, have one or more objectives

1'

Translation



• Certain parameters can be adjusted in order to optimize the

objective free variables).

• !unction, constraints, objectives and free variables Table 1)

define the boundary conditions for selecting a material.

• The first step in relating design requirements to material properties is a clear statement of function, constraints,

objectives and free variables.

1'

Translation



Table 1: Function, constraints, objectives

and free variablesFunction What does component do? to support a load, to contain a pressure, to

transmit heat, and so forth. This must beachieved

n#traint# hat nn6negtia%lecn"itin# mu#t %e met7

that certain dimensions are fixed, that thecomponent must carry the design loads without

failure, that it insulates or conducts, that it can

function in a certain range of temperature andin a given environment, and many more.

8%9ecti$e hat i# t %e maimie" rminimie"7

to make it as cheap as possible, perhaps, or aslight, or as safe, or perhaps some combinationof these.

Free;aria%le hat !arameter# ( the!r%lem i# the "e#igner (ree tchange

parameters can be adjusted in order to optimizethe objective – the designer is free to varydimensions that are not constrained by designrequirements and, most importantly, free tochoose the material for the component.

THE SELECTION STRATEGY




&onstraints

#s an essential

condition thatmust be met,usually e$pressedas a limit on amaterial orprocess attribute.

7bDective

#s a <uantity forwhich an e$tremevalue !a ma$imumor minimum" issought, fre<uently

cost, mass orvolume.



Assume that you were an &7 for &apAyam &ompany, how do you select thebest candidate to be your secretary@

Assume that you wanna buy a netbook,how would you decide which brand to gofor@

Disc(ss in)airs#



6trategy for materialselection involves fourmain steps3

:" Translating;" 6creening

" Canking

B" 4ocumentation




6trategy :3 Translating

Translating design re<uirement into function, constraints, objectives & free

variables.

unction@ &onstraints@

7bDective@ ree

variables@



unction

&onstraint

7bDective

reeEariable

6trategy :3 Translating



&ase 6tudies3 7ffice scissors

A material is re<uired to manufacture officescissors. (aper is an abrasive material, and scissorssometimes encounter hard obstacles like staples.ist function and constraints% set the obDective to“minimi5e cost* and the free variables to “choice of

material*.

Elements inDesignRe-&irement

E1planation

unction

&onstraints

7bDective

ree variables



A material is re<uired to manufacture office scissors.(aper is an abrasive material, and scissors sometimesencounter hard obstacles like staples. ist functionand constraints% set the obDective to “minimi5e cost*and the free variables to “choice of material*.

Elements inDesignRe-&irement

E1planation

unction 6cissors

&onstraintsF Gigh hardnessF Ade<uate toughness3 =:c H :I> (a.m J

F Kood wear resistanceF Able to be forged

7bDective >inimi5e cost

ree variables &hoice of material

&ase 6tudies3 7ffice scissors



A material is re<uired for a heat e$changer toe$tract heat from geo-thermally heated, saline,water at :;Lo& !and thus under pressure". istfunction and constraints% set the obDective to“minimi5e cost* and the free variables to “choice ofmaterial*.

Elements in DesignRe-&irement

E1planation

unction

&onstraints

7bDective

ree variables

&ase 6tudies3 Geat $changer



6trategy ;3 6creening

Unbiased selection + consider all materialsto be candidates

liminate candidates that cannot do theDob at all because their attributes lies

outside the limits (refer to constraints)

&onstraints@



6trategy 3 Canking



6trategy 3 Canking

#dentifying the candidates that remain ) orderingthose that can do the Dob best

>aterial inde$3

a" The property or property group thatma$imi5es performance for a given design

b" (rovide criteria of e$cellence that allowranking of materials by their ability toperform well in the given application

c" >aterial indices are generally e$pressed so

that a ma$imum value is sought

&onstraints setproperty limits.

7bDectives definematerial indices,for which we seek

e$treme values.



6trategy 3 Canking



&onventional method + employ selectionmatri$

$ample3 6haft

2ey re-&irements3

L GC& hardnessGigh impact strengthA minimum fatigue

strengthGigh stiffnessow cost

Selection candidates3

(rehard B:BL steel&ase hardened :L;L

steel

:M-B (G stainless steelTitanium A:BE

L:-T aluminum&LLL yellow brass

6trategy 3 Canking



6trategy 3 Canking



Candidate materials

(art structurere<uirements

0rass &LLLAluminumL:-T

TitaniumTiA:BE

6tainless steel:M-B (G

&arbon steel:L;L

(rehardenedsteel B:BL O

LGC&

L GC& minimum I :L :L P :L

L ksi endurance

limitB.B ;. :L Q. B.B :L

&harpy Eeeimpact H:I ft lb

P M :L :L :L :L

Gigh elasticmodulusR!/ factor"

:P!$"

:L!.$"

:P!$"

;M!Q$"

L!:L$"

L!:L$"

Custproof P P :L :L

>aterial costSlb

Q L.I I :L Q

Treatmentmachining costs S

:L :L :L I I I

?ill last I years :L :L :L :L :L :L

Score Q.B IQ. MP.I P. PL.B PM

<10 i# %e#t

6trategy 3 Canking



4ocumentationCanking6creeningTranslating

?hy @

=el!# narr the #hrt6li#t t a (inal chice 4iffers greatly from the structured property data )e#cri!ti$e / gra!hical / !ictrial > ca#e #tu"ie# ( !re$iu#

u#e# ( the material, "etail# ( it# crr#in %eha$iur in

!articular en$irnment#, in(rmatin ( a$aila%ilit&/!ricing,e!erience ( it# en$irnmental im!act#.

6ource3 handbooks, suppliers2 data sheets, &4-based datasources, www.

6trategy B3 4ocumentation



6trategy B3 4ocumentation

The selection strategy3 &ars



Requirements

expressed as

Constraints and

Objectives

Data:

Perormance

!conom"

What car? ratin#

Final selection

Comparison en#ine

$creenin#

Ran%in#

Documentation

Ma%e and Model

Dimensions

&umber o doors

Fuel t"pe

Po'er Fuel consumption

CO( ratin# ))

Mid si*e amil" saloon

+ doors

(,, - horse po'er

Least cost of ownership

Deliver" time

$ervice requenc"

&earest dealer

Warrant"

The selection strategy3 &ars

The selection strategy3 >aterials



Desi#n requirements:

expressed as

Constraints and

Objectives

Data:

Material attributes

Process attributes

Documentation

Final selection

Comparison en#ine $creenin# Ran%in#

Documentation

Densit"

Price

Modulus

$tren#th

Durabilit"Process compatibilit"

More)).

Able to be molded

Water and /0 resistant

$ti enou#h

$tron# enou#h

As light as possible

As cheap as possible

The selection strategy3 >aterials



Understanding &heck

?hy do we need to do screening ) ranking@

?hat is the difference between screening ) ranking@



The 0asics of >aterial 6election

ist three things that you are very clear of.

ist three things that you feel ha5y about.

ist three things that you need further clarification.



Tutorial:Translation: constraints an)

o.ecti3es:. A material is re<uired for the windings of an electric

air-furnace capable of temperatures up to :LLLo&.Think out what attributes a material must have if it isto be made into windings and function properly in afurnace. ist the function and the constraints% set theobDective to “minimi5e cost* and the free variables to“choice of material*.

;.A material is re<uired for a heat e$changer to e$tractheat from geo-thermally heated, saline, water at:;Lo& !and thus under pressure". ist function andconstraints% set the obDective to “minimi5e cost* andthe free variables to “choice of material*.

Ans0er:



Ans0er:Translation: constraints an)

o.ecti3es

Ans0er



Ans0er:Translation: constraints an)

o.ecti3es



4o we achieve our obDective for today2s lesson@



Why are all these steps necessary?

Without screening and ranking- the candidate-poo is

enor!ous and the "ou!e o# docu!entation

o"er$he!ing%

Screening-ranking steps ha"e identi&ed a s!anu!'er o# potentia candidates( So that detaied

docu!entation can 'e sought #or these #e$ aone(

!aking the task "ia'e%

)ocu!entation heps narro$ the short-ist to a &na

choice( ao$ing a de&niti"e !atch to 'e !ade

'et$een design re*uire!ents and !ateria

attri'utes%

S$MM!R&

Material Selection Lecture

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