Introduction to Composite Materials
What is a Composite?
A composite material is composed of at least two materials, which combine to give properties superior to those of the individual constituents.
For our website we refer to fibre reinforced polymer (FRP) composites, usually with carbon, glass, aramid, polymer or natural fibres embedded in a polymer matrix. Other matrix materials can be used and composites may also contain fillers or nano-materials such as graphene.
The many component materials and different processes that can be used make composites extremely versatile and efficient. They typically result in lighter, stronger, more durable solutions compared to traditional materials.
Why Use Composites?
The primary reason composite materials are chosen for components is because of weight saving for its relative stiffness and strength. For example, carbon-fibre reinforced composite can be five times stronger than 1020 grade steel while having only one fifth of the weight. Aluminium (6061 grade) is much nearer in weight to carbon-fibre composite, though still somewhat heavier, but the composite can have twice the modulus and up to seven times the strength.
Growth in the Composites Industry
The composites industry is an exciting industry to work in because new materials, processes and applications are being developed all the time – like using hybrid virgin and recycled fibres, faster and more automated manufacturing. The global composites materials market is growing at about 5% per year, with carbon fibre demand growing at 12% per year.
With around 1500 British companies involved, the UK composites product market was estimated at £2.3bn in 2015, and could grow to £12bn by 2030 (Reference: The 2016 UK Composites Strategy)
When Should you use Composites?
As with all engineering materials, composites have particular strengths and weaknesses, which should be considered at the specifying stage. Composites are by no means the right material for every job.
However, a major driving force behind the development of composites has been that the combination of the reinforcement and the matrix can be changed to meet the required final properties of a component. For example, if the final component needs to be fire-resistant, a fire-retardant matrix can be used in the development stage so that it has this property.
- The primary reason composites are chosen is improved specific strength / stiffness (strength / stiffness specific per unit weight).
- This helps to reduce fuel use, or increase acceleration or range in transport.
- It allows for easier, faster installation or faster movement of robot arms and reduces supporting structures or foundations.
- It improves topside stability in vessels and offshore structures and buoyancy for deep sea applications.
Durability and maintenance
- Composites don’t rust, which is crucial, especially in marine and chemical environments. The need for maintenance and painting is reduced or eliminated.
- Composite bearings for marine engines and bridges need no lubrication and don’t corrode.
- Combine the excellent fatigue resistance, and composites can increase product lifespan by several times in many applications.
- Composites are thermal insulators which is good for fire and blast protection or cryogenic applications.
- Electrical insulation is useful for railway lineside structures and radar transparency. A conductive mesh or coating can be integrated if needed, e.g. to reflect radar or divert lightning.
- Sensors, electronics and cabling can be embedded.
- Composites design allows for freedom of architectural form.
- Many parts can be consolidated into one, and stiffeners, inserts, etc. can be integrated in-mould.
- Composites can be tailored to suit the application by choosing the constituent materials and embedding extra functionality.