m6. composite materials m Flashcards
what is the term composite used to describe?
two or more materials combined to form a much stronger structure than the material by itself
wat are composite composed of?
a matrix and re reinforcing fibers
what state is the matrix and the reinforcing fibbers?
matrix is a liquid
reinforcing fibbers are a solid
what is the third component added to the composite?
a core material
what are the advantages of composite?
high strength to weight ratio
longer service life
higher corrosion resistance
design flexibility
easily repairable
what are the disadvantages of composites?
difficult for inspections
lack of long term design data base
expensive
toxic and hazardous
lack of methodology
what are the reinforcing fibers?
fiberglass
aramid
black graphite / carbon fibre
boron
ceramic
what is the most widely used composite?
fibereglass
how is fibre glass made?
glass heated up until molten then feed it through small holes to create glass filaments
what is the advantage of fibreglass?
less expensive
does not conduct electricity
what are the 2 most common types of fibreglass?
E glass and S glass
what is another name for aramid?
Kevlar
what types of aramid are the most communally used?
49 and 29
what are the advantages of aramid?
low density
flexible
high tensile strength
non flammable and non fusible
heat resistant
good chemical resistance
high toughness
what prevents aramid turning brown?
protection from the environment
carbon fibre is very what?
strong and used for its rigid property’s
carbon fibre has stronger compressive strength than what?
Kevlar
what are the advantages of carbon fibre?
high strength
low density
low fracture resistance
resistance to high temps
good electrical conductivity property’s
what are two different materials we use as sandpaper and which one will last longer?
aluminum oxide and silicon carbide
silicon carbide lasts longer
how is boron made?
apply small amount of vaporized boron onto tin tungsten or carbon wire
what is boron used for?
cracked aluminum parts and panels
wat are the advantages of boron?
excellent compressive strength
high tensile strength
high stiffness
very hard wearing
when are cermic fibers used?
when high temp application is needed
cermic reattains most of its strength and flexibility up to what temperature?
1200 degrease Celsius
what is the warp?
along the length of the fabric
what is the weft / fill?
perpendicular to the warp fibers
what is the salvage edge
tightly woven edge
parallel to warp threads
prevents unraveling
what is the bias?
45 degree angle to warp threads
what are the different styles of fabric?
unidirectional
bidirectional
quai isotropic
mats
what are unidirectional fibers?
major fiber runs in warp direction
what are bidirectional fibres?
fibres run in two or more directions
what is quasi isotropic lay up?
carbon fiber piles stacked in 0, -45, 45, 90 or 0, -60, 60
what are mats?
chopped fibers that are compressed
the orientation of the lay up results in what?
constant strength and stiffness
wat are mats used with?
woven or unidirectional layers of fabric
where are mats used?
marine industry
wat are fibric waves resistant to?
fibre break out
delamination
damage
what are the most common types of plain weaves?
plain
twill
satin
what are the characteristics of a plain weave?
simplest form of weave
stable
difficult to cover complex shapes
high degree of crimp
what is the characteristics a twill weave?
provide superior wet out to plain weaves
flatter
more mechanical properties bc of reduced crimp
what are the characteristics of a satin weave?
modified twill weaves with fewer inter sections
flat
facilitates wetting out
good mechanical properties
difficult to handle
used for repairs
wat is the matrix?
bonding material that surrounds the fibers
what is an example of an early matrix?
polyester
what does a resin matrix consist of?
resin and a hardener
what are the two general categories of plastics?
thermosetting
thermoplastic
what are thermosetting plastics?
use heat or a catalyst to set
low melting points
can not change from new position
what are thermoplastics?
heat up to form desired shape
can be reheated to change shape
what uses epoxy resins?
most advanced composite materials
what are epoxy resins well know for?
good strength and resistance to moisture and chemicals
is every type of epoxy suitable for every repair?
no
where is information about epoxy resins?
product safety data sheet
what are pre pregs?
fabrics that already have the correct amount of resin already saturated into the fabric
