Download Composites

Adam Lebaigue pg end of 39 - 41
Composites
 When two or more materials are combined by bonding
 The finished material has improved mechanical, functional and
aesthetic properties
 And normally the material has excellent strength to weight ratios
Examples:
Glass Reinforced Plastic:
 Made of polyester OR epoxy resin which is reinforced with glass
fibres in the form of a woven matt
 The plastic resins are strong in compressive strength but weak in
tensile strength
 The glass fibres are weak in compressive strength but strong in
tensile strength
 Used in boats and cars
Carbon fibre:
 Made up of carbon fibres which take tensile loads set in a polymer
resin which takes compressive loads
 The fibred are woven into a mesh with is strong in one direction,
this mesh is then combined with other meshes that criss-cross
 Much stronger than glass reinforced plastic (GRP)
 Has more than four times the tensile strength of the best steel
alloys at just a quarter of the weight.
 Also has a better fatigue life
Medium Density fibreboard:
 Made from wood waste (softwoods) in the form of wood chips
 These chips are subjected to heat and pressure to turn them into
pulp
 The pulp is then mixed with resin adhesive with is then pressed to
give a fine textured finish
 Sometime it is also laminated for extra strength
 MDF can be worked like wood but I has no grain
 HAZARDS when using MDF include fine fibres and fumes from
glues that can affect the lungs
Adam Lebaigue pg end of 39 - 41
Applications
Advantages
Disadvantages
Applications
Advantages
Disadvantages
Glass Reinforced Plastic
 Rotor blades of wind
turbines
 Canoes
 Fish ponds
 Vehicle bodies
 Boats
 Fairground rides
 Excellent strength to weight
ratio
 Resistant to corrosion
 Water resistant
 Ideal for external shell
structures
 Wide range of colours can be
added with pigments
 Can be easily repaired
 Expensive
 Specialised manufacturing
process needed
 High quality mould needed
Carbon Fibre
 Sport equipment (tennis
racquets)
 Fishing rods
 Bicycle frames
 Aircraft
 Vehicle components
 Excellent strength to weight
ratio
 Better tensile strength than
steel alloys
 Can be engineered to give
support to only certain parts
of the structure
 Can be formed into complex
one piece structures
 Very expensive
 Only available in black
 Highly specialised
Adam Lebaigue pg end of 39 - 41
manufacturing
 Cannot be easily repaired
 Cannot be easily recycled
Applications
Advantages
Disadvantages
MDF (Medium Density Fibreboard)
 Flat pack furniture
 General joinery work
 Moulds for forming
processes
 Less expensive than timbre
 Available in large sheet sizes
with a range of thicknesses
 Consistent strength in all
directions
 Heavier (the resin makes it
heavy)
 Requires appropriate finishes
to seal the surface
 Swells and breaks when
waterlogged
 Warps or expands if not
sealed
 Contains urea-formaldehyde
which can cause eye and
lung irritation
 Dulls blades more quickly
than other woods