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JANUARY 2011: TEST 1 (07-March-2011)

PART A. Choose and tick the BEST answer.1. Materials engineering includes the study ofa) Allotropy.b) Crystallinity.2. Product service life is determined bya) estimates.b) property tests.3. Failure of products is m/thly due to $s.*,ilili,i;lnsufficient costlnsufficient paintQuestions 4-6 are referred to the followine figure. You have to suggest the BEST type of,mateflAj tor A, B and Cbased on their stress-strain curves shown. Please be noted that A,B and C are bel6-rUing i6'ilifferent materials.

a) lnsufficient color ,/ o=t@nsuffic i"nt *t{"rftt[ c)d)

is a -physical property.a) Fracture toughnessb) Corrosion

A: Glo,+, V/Ur,

c) Formabilityv/

a, PoUe{l,ler,e , Fr-( P('ar)c. Cr*?or,f e 4@;x)

ooG)U) 4.

5.6.

7.

8.

c)@ 6tivityd) Durability"z

a)b)

ConductivityCompositionfis one of the mechanical properties.

Texturelonization

ifrglecking

mechanism can be seen when the stress is e5$g$e value ofModulus strengthIDesign strength(

./-(ri]r*V ( ,Yj corrosion;t-----c)d)

c)d)

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-MBB3023/MA82023 JANUARY 2011: TEST 1 (07-March-2011)

12. Figure Q12 below shows a fairure occurs in a right prane due toae^AV a E.L " a)@c)

d)

tnsuffifitdensity*rnsffii{nt stiffnesstnade\ua-te strengthAllof above ,lL

a) Maximum bend;rTgtemperatureb) MaximuT $*pg temperaturec) Maximutti {rro{ying temperature(db vt axim u m hdeem peratu re

o*-t F'1fu'e"F"

,*'3o13. The strength of materials fails, it starts to 'creep' (to sag slowly over time), it may oxidize, degrade ordecompose (Figure Q13 below). This means that there is a limiting temperature called:

14. Most materials willgenerate immediate response or result when they are heated (example shown inFigure Q14 below), but by different amount depending on their...

c) thermal explosive coefficientf.d) thermal exclusive coefficientf,

15. A materials engineering factor that can apply to wei.r,.fail{res isa) Moisture absorption -@h.rdness) Microstructure @Ail of the above16. Where is Poisson's ratio Nsdd? - 2 t^^a(ll rensile results. I \ 2 ut*t c) Etongation testingsat.tt calculations/,/ ' d) Reduction in area catcutationi- \Ar*la\17. hlhich of the tottoydnpraness designations conforms to coggnsus s:ranc!:rds? I,W > dolo^,a 1a*@ ars Ha \ ,/ "/l --- ---e - - ;i';;i Knoop Hardnesslb) 315 Brinelf'HardnQ_ d) 3l Rockweil C A18.Tgrtgbnot of materials can be measured by all ofa) Tensile testing y'b) Ktc J

a) Shear strengthb) Bending modulus/

the

c) micrometerd) a gage length20. A traditional tensile tester can perform all of the following cal property tests EXCEPT

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tnJ

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PART B: Answer ALL questions.130 markslB1'Atensiletestingmachinesimila/qthefol]owingtigureof 400 kN. The design calls for@9)cylindrical support posts which must together sustainthe maximum load. The machine is to be constructed from plain-carbon (1045) steel*li.l tr a and r t"n topoE'suitabletQ!-ametg;\for these support posts. Justify. 110 marks .,/ .,

P'* = 4ookr'f F= +oottL /"ot rlVy, = ?lofuPq zt1', tor^Po6,fu /q'ti)cs* " s)t7 = r:,^!" 2 \9SMpa

@5w=

f,=trA

tr-lo6,,"zoour!{ . l,2q\75APA

,Z-_ 1cl+-t'-= I+AIJA

d" o.o+o5

Load *ell

9 trnn

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E - zo:16?c ,/do -"J& z^n -(,olrlLy,p = 01oo rrlL"--?I F = 6'zimfin : 0, aSXl g -3rr., f

E= 0-L o^=jA

= a^r/wrrt

F-4oc'- ('L--- E

/nr:Tk /,,r't,^fu/nb,o,oz)3-

ct ,-Dr.qzrn?e 4r^rk,^,zoTlaP-a

5.26t lo- + -_9.2Lylo-\'Lo g

l, oo 0526 t;.4 _-ro,/

,LO

o-rg xlo- '- Lo-- o.zS), lD-,- z.gx;f,Vt

l, ooo iz[Io . 0L93

,/g,zlxlr-.l +*.2(xlo-Y L . o r,/ r"

A.cylindricaoriginal .di?metgr of 10.2 mm. The specimeliwill"- -r-when a tensite lGTiTS@rN ii apptied.ilriil a reltslteloao jl.ro-l\ ts appllecl.o"t"-inffi *,i"--:f:cimen lgfore deformguon if the maximumZ9 mm. 110 marksl

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83, Some aircraft component is fabricated from an aluminum alloy that has a plane strainfracture toughness of-40 tttipa.ti). lt has been determined t6t*iL*ctur" i-illb "t "tress of 300 MPa when the maximum (or critical) internal crack 6ngth G 4.0 mm. Forthissamecomponentand",,o,,*ffiffi,ji::}*,ilfuenthemaximum internal crack length\is6:0-inr?-'wt y or *trv noti tnlnisllr" you have todetermine the shape factor (v) o.aseo on tne given ion.110 nlarksl

kr., r+omf. .[ic* = 3oo6p4C' 4'omn '

,/\ t., -,- '/-1v,, . y c JTif /2,, v,r= ((tfi) (z6o ) ryeEt 5-4o{ =rt"r;@ - \--=-- -4)'--z ,4+ u P" JFY=ffi:\aoo ^ @__..-,t' +z,Qvrp" Jf f:?o KJ .A E" '')L: rreq-_;l 6, (Ul:- ,tr fuqo+are will ocaqk' wlt