composites Flashcards
what is PMC
polymer matrix composites
a composite consisting of a polymer imbedded with reinforcing phase
what are shaping processes for PMC
open/closed mold proocesses
filament winding
pultrusion
What is a FRP
Fibre reinforced polymer
what is a reinforcing aject
fibres
particles
flakes
what are some of the forms of continuos filiment
Roving- untwisted strands
yarn-twisted filiments
cloth-woven yarns
woven roving- fabric constisted of untwisted filaments
Mat- felt consisted if short fibers held together
preforms- mats that are shaped for lclose molding processes
what is open mold processes
procwsses that use a single positive or negitive mold to produce the sructures
what are 3 examples of open mold processes
hand lay up
spray up
automated lay up
what is the process for the hand lay up method
- coat mold with release agent
- a thin coat of resin is appliedto the outside of the mold
- when the resin is set more layers of resin and fibers areapplied
- part is cured
- part is released
whhat kind of products are suited for hand lay-up
large in size but low in quality
what can hand lay up molds made from
plaster prototypes
FRP - for medium volume
Matel- high volume
what are some applications for hand lay up
boat hulls
swimming pools
large container tanks
other formed sheets
what is the spray up method
liquid resin is sprayed onto an open mold
spray gun moves fibers 1-3 inches long and add them to resin stream
what are automated tape laying machines
a machine that dispenses prepeg tape onto a an open mold
what are some applications made by spray up methods
boat hulls
bath tubs
shower stalls
automoative body parts
rv components
furnature
large structural pannels
containers
what is prepeg
a composite material made for pre impregnated fibers and parially cured polymer matrix
what are automated fiber placement machines
despenses prepegs in flat bundles of fibers impregnated with resin
closed mold processes basics
preformed in molds with 2 sections
tool costs twice as much as open molding as more complex equipment is required
what are the advantages of closed mold processes
good finish
high production rates
closer control on tolerances
more complex 3 diensional shapes
what are 3 closed molding processes
compression
transfer
injection
what is are the 2 differnet types of compression molding
preform
elastic reservoir
what is preform molding
placemeny of a pre cut mat into lower mold secrion and resin goes into the fiber mat
what is elastic reservoir molding
a sandwich of a foam core has liquid resin brought between the 2 dry fiber layers
what is tranfer molding in composites
very similar to the plastic version in that fluid polymer is transfered fro pot to mold
what process can mold thermosets with short fibres
transfer molding for composites
what is a common variation of tranfer molding
resin transfer molding
what are the materials in injection molding
thermoplastics
thermosets
what is the one thing that has to happen in the injection molding
the chopped fibers must be used
what happens to to the fibers during the injection molding process
they become aligned which can create directional properties
what is filament winding
continuios fibers are wrapped around a rotating mandrel
what is pultrsuion
similar to extrusion but filament is pulled through a die
what are the 5 steps of pultrsuion
- filament feeding
- dipping fibers in resin
3.pre die forming - shaping and curing
- pulling and cutting
what are some other PMC shaping composites
centrifugal casting
tube rolling
continuous laminating
cutting of FRPs
what are the 2 basic steps in good rubber production
production of rubber
processing into finished products
what are the steps in processing for rubber
compounding
mixing
shaping
vulcanizing
what is coumpounding
adds chemicals for vulcanizing
why are dditives added in rubber
tgo enhance mechical properties
to extend the rubber cost
what is carbon black
the most important filler in rubber
what is the effect of carbon black
increase tensile strength
increase resistance to abrasion and tearing
provides protection for ultraviolet radiation
what is mixing
additives being mixed into the rubber
what are the 2 stages of mixing
1) carbon black and non vulcanizing addives are added
2) vulcanizing agents are added
what is vulcanization
a treatmet that accomplishes the crosslinking of the elastomer
what is the purpose of filament reinforcement
reducue extenibility but retain other desirable properties
what are bthe 4 basic catagories of shaping
extrusion
calendering
coatikng
molding/casting
what is some exapmes of rubber products
footwear
seals
shock absorbition parts
converyor belts
foamed rubber products
sports equipment
what sre the 2 types of hoses
plain hose
reinforced tube
