85310
Descrição
Mapa Mental por Poppy Venables, atualizado more than 1 year ago
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Criado por Poppy Venables
mais de 11 anos atrás
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Composites
- When two or more materials are combined by
bonding, a composite material is formed.
- A composite has improved mechanical,
functional and aesthetic properties
- Glass Reinforced Plastic (GRP)
- Made of Polyester or epoxy resin reinforced by fine fibres of glass in the form of a woven matting.
- By combining the 2 materials GRP has both compressive and tensile strength.
- The plastic resins are strong in compressive strength but relatively weak in tensile strength.
- Glass fibres are very strong in tensile strength, but have no compressive strength.
- The plastic resins are strong in compressive strength but relatively weak in tensile strength.
- The resin exists in a liquid form and has a catalyst or hardener added to become a solid.
- The glass fibre strands provide the basic structure, while the resin with its
additives, bonds the fibres together and provides a lightweight rigid structure.
- The extremely smooth GRP finish seen on boats and some cars is achieved by a highly polished surface on the mould used and
careful application of the first layer, known as the gel coat. The glass matting which is laid on top of the gel coat to provide the
basic structure leaves a very rough finish.Therefore, one surface of GRP is highly polished whilst the other is extremely rough.
- Applications
- Rotor blades of wind turbines
- Canoes
- fish ponds
- vehicle bodies
- fairground rides
- Rotor blades of wind turbines
- Advantages
- Excellent strength to weight ratio
- Resistant to corrosion
- Water resistant
- Ideal for external shell structures
- Can be easily repaired
- Wide range of colours as pigments can be added to resin
- Excellent strength to weight ratio
- Disadvantages
- Expensive material
- Specialised manufacturing process
- High quality mould needed
- Expensive material
- Made of Polyester or epoxy resin reinforced by fine fibres of glass in the form of a woven matting.
- Carbon fibre
- This carbon composite is made up of carbon fibres, which take tensile loads, set into a polymer resin matrix that takes the compressive loads
- Carbon fibre is a filament material incorporating thousands of filaments that are woven to form a fabric. However, this fabric only has strength in tension.
- So the fabric is placed in different directions to cover different tensile loads in all directions.
- Carbon fibres are much stronger than GRP and are ideal for high performance
structural applications in aircraft, sports equipment and F1 racing car manufacture.
- Applications
- Sports Equipment
- Bike frames and wheels
- Fishing rods
- tennis racquets
- Bike frames and wheels
- Aircraft and vehicle components
- Sports Equipment
- Advantages
- Excellent strength to weight ratio
- Better tensile strength then steel alloys
- Can be engineered to be fabric orientated in different
directions to provide strength in specific areas of
construction
- Can be formed into complex and aerodynamic structures
- Excellent strength to weight ratio
- Disadvantages
- Very expensive material
- Only available in black
- Highly specified manufacturing processes needed
- Cannot be easily repaired as structure loses integrity
- Cannot be easily recycled
- Very expensive material
- This carbon composite is made up of carbon fibres, which take tensile loads, set into a polymer resin matrix that takes the compressive loads
- Medium Density Fibreboard (MDF)
- Made from wood waste in the form of wood chips, which are subjected to heat and pressure in order to
soften the fibres and produce a fine, fluffy and lightweight pulp. The pulp is then mixed with a synthetic resin
adhesive to bond the fibres and produce a uniform structure and heat pressed to form a fine textured surface.
- MDF can be worked like wood, with the added advantage that it has
no grain. It also finishes well with is variety of surface treatments
and is available with a veneered surface for decorative effect.
- Advantages
- Less expensive than natural timbers
- Available in large sheet sizes and range of thickness
- Isotropic (no grain), so no tendancey to split
- Consistent strength in all directions
- Less expensive than natural timbers
- Disadvantages
- Heavier (the resins are heavy)
- Requires appropriate finishes to seal surface fibres
- Swells and breaks when waterlogged
- Warps or expands if not sealed
- Contains urea-formaldehyde which may cause eye and lung irritation when cutting and sanding
- Dulls blades more quickly than many woods
- Heavier (the resins are heavy)
- Applications
- Flat pack furniture
- General joinery work
- moulds for forming processes
- Flat pack furniture
- Made from wood waste in the form of wood chips, which are subjected to heat and pressure in order to
soften the fibres and produce a fine, fluffy and lightweight pulp. The pulp is then mixed with a synthetic resin
adhesive to bond the fibres and produce a uniform structure and heat pressed to form a fine textured surface.
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