21-01-2013, 12:02 PM
Introduction to Composite Materials
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Why Composites ?
A composite is a mixture of two or more
phases (materials).
A better or unique combination of properties
is realized when different materials (or
phases) are combined
The primary needs for all the advanced
composites are:
light weight, higher operating temperatures,
greater stiffness, higher reliability and affordability
What are composites made of ?
Human learns from
‘mother nature’ to
develop new
composite materials
Natural Composites:
wood and bamboo,
shells, bones,
muscles, other tissues
and natural fibres (silk,
wool, cotton, jute,
sisal)
Reinforcements
• A reinforcement is the strong,
stiff integral component which
is incorporated into the matrix
to achieve desired properties
• The term ‘reinforcement’
implies some property
enhancement
Different types
Fibres or Filaments:
continuous fibres,
discontinuous fibres, whiskers
Particulates reinforcements
may be of any shape,
ranging from irregular to
spherical, plate-like or
needle-like, nanoparticles
• They are all easy to break (low
ductility)
Polymer Matrix Materials
Thermosets
A thermoset may not be re-melted once cured (crosslinked).
Polyester & vinylester resins: low cost applications
Epoxies: aerospace application due to the better resistant
against moisture and mechanical properties
Thermoplastics
May be melted or softened at an elevated temperature
repeatedly
Higher temperature applications using polypropylene (PP),
polyimide (PI), Nylon
Glass Fiber-Reinforced Polymer (GFRP)
Glass fibres (or Fibre Glass) :
Easy to manufacture, chemical
resistance
Glass fibre surface is coated
with a thin polymer layer, i.e.
“size”, to protect the fibre
surface from damage
GFRPs’ use temperature is
limited below 200°C due to
polymer matrix
Major applications of GFRPs
Automotive, marine vehicle
bodies, pipes, storage
containers, industrial flooring
Applications of Polymer matrix
Composites
Aerospace: wings, fuselages, landing gears,
rudders/elevators, rotor blades, satellite structure
Automobile: body panels and frames, bumpers,
leafsprings, drive shafts, seat housing, tyres and
other ground transportation vehicles (bullet train).
Marine (e.g. Catamaran) : boat hulls, decks, masts,
propeller shafts, wind surfer
Chemical plants: process pipes, tanks, pressure
vessels, oil field structures