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ISSUES TO ADDRESS...
What are the classes and types of composites?
1
Why are composites used instead of metals, ceramics, or polymers?
How do we estimate composite stiness & strength?
What are some typical applications?
CHAP!" 1#$C%P%'(! A!"(A)'
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*
Composites$
++ultiphase material wsigni-cant proportions of ea. phase. atri/$ ++he continuous phase ++Purpose is to$
transfer stress to other phases protect phases from en0ironment
++Classi-cation$ C, CC, PC
ispersed phase$ ++Purpose$ enhance matri/ properties.
C$ increase y, ', creep resist.
CC$ increase 2c
PC$ increase !, y, ', creep resist.
++Classi-cation$ Particle, -3er, structural
metal ceramic polymer
wo0en
-3ers
crosssection0iew
4.#mm
4.#mm"eprinted with permission from. Hull and .W. Clyne,AnIntroduction to CompositeMaterials, *nd ed., Cam3ridge5ni0ersity Press, 6ew 7or8, 199:,;ig. .
!"(6%)%7C)A''(;(CA(%6
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1.
Adapted from ;ig.1:.=, Callister 6e.@;ig. 1:.= iscourtesy Car3oloy'ystems,epartment,
eneral !lectricCompany.
Adapted from ;ig.1:.#, Callister 6e.@;ig. 1:.# iscourtesy oodyear
ire and "u33erCompany.
C%P%'(! '5"B!7$ Particle+(
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=
!lastic modulus, !c, of composites$ ++ two approaches.
Application to other properties$
++ !lectrical conducti0ity, e$ "eplace ! 3y e.
++ hermal conducti0ity, 8$ "eplace ! 3y 8.
;i3er+reinforced 'tructuralParticle+reinforced
ata$Cu matri/wtungstenparticles
4 *4 =4 :4 E4 144
1#4
*44
*#4
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#
Aligned Continuous-3ers
;i3er+reinforcedParticle+reinforced 'tructural
!/amples$
;rom W. ;un8 and !. lan8, FCreepdeformation of 6i+99E, 19EE. 5sed with
permission.
fracturesurface
matri/$ @o @ductile
-3ers$J @6i
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@/
>
Critical -3er length for eecti0e stiening & strengthenin
;i3er+reinforcedParticle+reinforced 'tructural
-3er length> 1#fd
c
-3er diameter
shear strength of
-3er+matri/ interface
-3er strength in tension
!/$ ;or -3erglass, -3er length O 1#mm needed Why? )onger -3ers carry stress more ecientlyD
-3er length> 1# fd
c
'horter, thic8er -3er$
-3er length< 1#fd
c@/
)onger, thinner -3er$
Poorer -3er eciencyetter -3er eciency
Adapted from ;ig.1:.>, Callister 6e.
C%P%'(! '5"B!7$ ;i3er+(((
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!stimate of !cand '$ ++0alid when
++ !lastic modulus in -3er direction$
++' in -3er direction$
eciency factor$++aligned 1$ 2 L 1 @anisotropic++random *$ 2 L
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;i3er +reinforcedParticle+reinforced
9
'tructural
'tac8ed and 3onded -3er+reinforced sheets ++ stac8ing seQuence$ e.g., 494 ++ 3ene-t$ 3alanced, in+plane stiness
'andwich panels ++ low density, honeycom3 core ++ 3ene-t$ small weight, large 3ending stiness
Adapted from;ig. 1:.1:,
Callister 6e.
Adapted from ;ig. 1:.1>,Callister 6e. @;ig. 1:.1> isfrom Engineered Materials
andboo!, Bol. 1, Composites, A' (nternational, aterials Par8, %H, 19E>.
C%P%'(! '5"B!7$ 'tructural
honeycom3adhesi0e layer
face sheet
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CCs$ (ncreased toughness PCs$ (ncreased !
Cs$ (ncreased creep resistance
*4
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Composites are classi-ed according to$
++ the matri/ material @CC, C, PC ++ the reinforcement geometry @particles, -3ers, layers.
Composites enhance matri/ properties$ ++ C$ enhance y, ', creep performance
++ CC$ enhance 2c ++ PC$ enhance !, y, ', creep performance
Particulate+reinforced$ ++ !lastic modulus can 3e estimated. ++ Properties are isotropic.
;i3er+reinforced$ ++ !lastic modulus and ' can 3e estimated along -3er dir. ++ Properties can 3e isotropic or anisotropic.
'tructural$ ++ ased on 3uild+up of sandwiches in layered form.
'5A"7
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"eading$
Core Pro3lems$
'elf+help Pro3lems$
4
A66%56C!!6'