reinforcing fibers and thier properties
effect of fiber volume
by increasing fiber volume representwdby fiber diameter thestrength will decrease
fiber classification
naturalfiber
chemical fiber(synthetic fiber)
syntethic fiber : organic fiber ,anorganic fiber
anorganic
glass fibers
organic fiber
aramide fiber
carbon fibers
influence of fiber
deacrese : deformability, sliding properties , tendency to creep , thermal expansion
increase : notch sensivity,thermal deformation resistance , stiffness and strength, anisotropy,warpage
fiberglass
most used reinforcing fiber
3d cross linking with covalant bond
amorphous structure
isotropic properties
originally developed for electrical application.
oxygen,silicon,aluminum,boron,sodum
*fiber forming through melt spinning
properties of glass fiber
no viscos behavior
no flammable
resistant to organic and inorganicacid
isotropic properties
relativelycheap
permeable to radar emission
ad & disad fiber glass
dis :low youngmodulus, aging through water contact,brittle,sensitive to basic enviroment
dis:
good adhesion toresin,low thermal expansion,low electrical conductivity,low cost,good dielectric properties
fiber glass type
R,S,R
E: mostly sio2 with ca/mg/Al/B-oxide
good electrical properties
most commenly used glass fiber
S : more Alinumoxide,higj strengyh stiffness at low density,used in aerospace, more expensive than E glass
R : with calciumoxide, higher stiffnes but higher density,used for specialapplication
production of fiber glass
direct roving
chopped fiber
production fiber mat type 1
glass input
melting
fiber pulling
binder
forming
collecting belt
dryer
fiber mat
production fiber mat type 2
dispersion of fibers
filament dispersion
dryer
fiber mat
carbon fiber
the most common used
high performance composite material
2d layer structure
covalant bond onlyinthe plane
para crystalline(100)
high orientation
carbonfiber properties
low density
buckling sensitive and brittle
E modulus increase with increasing load
sizing and roughing prove the surface adhesion of the matrix
ad & dis adv
ad:
excellent specific properties
temperature resistance 2000
no thermalexpansion
good electrical and thermal conductivity
corrosion resistant
dis adv:
expensive
adhesion to resin is difficult
at high temperature not resistant against oxidizing enviroment
carbon fiber type
lm. low
im intermediate module
hm high modulus
uhm ultra high modulus
ht high tensile strength
hst high strain
pan (polyacrylnitril)
raw material
ca 68, c6,h 24?N
advantage:
high strength
generally good mechanical propertues
disadv:
carbon yield only less than only 50
precourser is expensive,bcs they are very complex production
pitch
basic material: C,H,N,O
ad: efficency carbonuse
precourser less expensive and easierto produce
disadv:
low strength
precursor fiber brittle and easy tobreak
aramid fiber
organic high performance
1d
covalant bond in the chain
paracrystal
very high orientsyion
low thermal cond
good chemical temperature resistance
uv sensitive
moisture ibsorption
dis advatage aramid fiber
very high cost
mosture obsorption
uv sensitive
worse resin adherence
low strengh
advan aramid fiber
very good impact strength
very good fatigue behavour
very good dsmperbproperies
very good spesific ptopetties
aramidfibertyoe
hm: low module,fircable and ballistuc vests
HM: high modulus,fiber used in high performance composite