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Syllabus
Syllabus
• show an understanding of the term composite and be aware of the practical applications for each of the following composite materials:
– Kevlar®
– carbon fibre reinforced plastic (CFRP)
– glass reinforced plastic (GRP)
Learning Outcomes
Learning Outcomes
By the end of this unit you should have developed a knowledge and
understanding of:
the specific names and classifications of composites
what constitutes a composite material
the performance characteristics of different types of composites
why different types of composites are suitable for different applications
common composite based products
the benefits of using composite materials
Introduction - Composite materials
Introduction - Composite materials
A composite is a mixture of materials combined to enhance their individual properties.
A composite is a mixture of materials combined to enhance their individual properties.
Composites generally fall into one of two groups; fibre based composites and particle based composites.
The most important of these for your exam are the fibre reinforced composites since they are most commonly used in the manufacture of products!
Fibre Based
Fibre Based
Reinforced with fibres
GRP, CFRP
Particle based
Particle based
Reinforced with particles
Concrete, GRC (glass reinforced concrete), Cermets
Fibre-based composites
Fibre-based composites
These composites have the following characteristics:
good strength to weight ratio.
resistance to corrosion.
good fatigue resistance
low thermal expansion
Glass Fibre or Glass Reinforced Plastic (GRP)
Glass Fibre or Glass Reinforced Plastic (GRP)
Glass Fibre shapes are made by ‘laying up’ as in the diagram.
Glass is spun to produce a fibre which is then coated to aid bonding to the resin.
The fibres of glass are available in a variety of thicknesses from coarse to very fine.
The Polyester Resin used is quite brittle on its own and the glass fibres are relatively useless without the resin to bind them together.
The composite material produced is called Glass Reinforced Plastic or GRP.
A mould is required for GRP and these can be produced quite cheaply but their surface can often affect the final quality of the GRP shell.
Inserts such are reinforcing struts and mounting plates can be included while the material is being ‘laid up’.
Laying up method
Violin and case
boat hull
boat hull
Surf board
Carbon Fibre Reinforced Polymer (CFRP)
Carbon Fibre Reinforced Polymer (CFRP)
Carbon Fibre Reinforced Polymer (CFRP) such as matting has become popular in the production of F1 car bodies, tennis racquets and other performance equipment.
Carbon fibres are woven into a matt which is cut to shape. This is what gives carbon fibre its distinctive look.
This is then placed in a mould where it is impregnated with resin and forced into shape.
The mould parts are then baked at 170C for up to 8 hours to promote the rigid cross links in the resin.
Road bike
Automobile parts
Prosthetics
Sports equipment
F1 Racing
Sports equipment
kevlar
kevlar
Kevlar
Kevlar
Kevlar is a mixture of aromatic and aramid (Nylon-like) molecules melted together and spun into fibres. This material has a very high strength, and weight for weight, is five times stronger than Steel but half the density of Fibreglass. It has high chemical resistance and high cut resistance as well as being flame resistant.
It has various uses:
body protection, armour and helmets.
sports equipment
sails for windsurfing
run flat tyres that will not damage the rim
gloves for use with glass and sheet metal.
Tyre lining
Sails
Work gloves
Kevlar sports gloves
Kevlar used in skis
Protective body armor
Applications for composites
Applications for composites
Kitchen Knives
Kitchen Knives
Traditionally made from metal, knives can now have ceramic edges which result in a sharper and more durable cutting edge.
flooring
flooring
Traditionally made from wooden planks, flooring is now made from sheets of chipboard or MDF due to stability and low cost.
bicycle frames
bicycle frames
Once made of Steel, then Aluminium alloy, frames on more expensive bicycles are now made of Carbon Fibre. The first example of this was the Boardman bicycle, designed by Lotus car company, which helped its rider Chris Boardman win gold at the 1992 Barcelona Olympics. Carbon fibre frames are now common but have a higher price point than aluminium frames.
Summary
Summary
composites are a mixture of materials combined to improve their properties.
composites generally fall into one of two groups; fibre based composites and particle based composites.
fibre based composites include Carbon Fibre, GRP (glass reinforced plastic) and Kevlar
composites are now being used to replace traditional materials such as timber and metal.
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