Are you looking for an exciting, challenging, multi-disciplinary subject to study at postgraduate level? One which is at the cutting edge of technology, and which offers the potential to launch a career in a wide variety of industrial sectors, almost anywhere in the world? That is what you get if you choose to study Composite Materials, which combines elements of engineering, physics, chemistry, materials science, design, fabrication and testing.

Composites offer an increasingly important range of new and developing materials which find applications in many modern industrial spheres, including machinery, medical goods, chemical plant, sports goods, aerospace, road vehicles, ships, trains, buildings and civil engineering. They find these applications because they are the best material available for the job, and can have their properties tailored to suit the particular requirements. There are many reasons why a composite material may be preferable to a 'conventional' material such as metal, plastic or ceramic. It may be that a component with a zero coefficient of thermal expansion is required; the weight of a component needs to be reduced by 30%, the stiffness or strength needs to be doubled; the number of sub-components has to be reduced; the cost reduced; or the fatigue life or operating temperature increased.

So, what are these composite materials? We are talking of materials created by the deliberate combination of two, or more constituents, with the aim of having properties that are distinctly different to those of the constituents. The stronger, stiffer and harder constituent, known as the reinforcement, is incorporated in the matrix, which is usually a polymer, but could also be a metal or ceramic. The reinforcement is normally in fibrous form, typically 8 microns in diameter, and could be of glass, carbon, thermoplastic polymers such as aramid or polyethylene, silicon carbide, or some other material such as natural fibres. Polymer matrices could be thermosetting resins, such as epoxy or polyester, or thermoplastics such as nylon, polypropylene, polyether etherketone, and so on. Metallic matrices are usually alloys of aluminium, which would be reinforced with fibres such as silicon carbide, silicon nitride or alumina, which can be processed at high temperature. Ceramic matrix composites would normally employ the same type of reinforcements as metals.

There is clearly an almost bewildering array of fibre/matrix combinations at our disposal, giving a freedom to design the material, as well as the component, to meet a particular specification. Part of this design process must include consideration of the production process since, usually, the composite material does not exist until the component is fabricated. This is quite unlike metals, which are obtained 'off the shelf' and have properties that, by and large, are not altered during processing.

Over the past 30-40 years there have been an enormous number of successful applications of composite materials. The use of these new materials has frequently produced a quantum leap in performance, which could not be achieved using conventional materials. Examples include: Grand Prix racing cars; mine hunter ships and fast patrol craft; racing power boats; America's Cup and round the world yachts, as well as smaller craft; military and civil aircraft; helicopters; spacecraft; personal protection and tank armour; bridges and buildings; desulphurisation plant; off-shore applications; crash helmets; machine components; trains; road vehicles; artificial limbs and other medical devices; tennis and squash racquets; golf clubs; fishing rods; skis, poles and snow boards - to mention just a few.

The full-time Composite courses are typically of 12 months duration, consisting of six months of lectures and coursework followed by six months of research project work. Lectures are divided into subject areas covering fibres, matrices, the interface, composite systems, production methods, micro and macromechanics, mechanical performance, analytical techniques, mechanical testing and design. Design lectures are often given by speakers from industry. In coursework programmes, there are laboratory periods in which students follow the procedures of fabrication, testing and analysis of a typical composite, as well as researching the published literature on a particular topic in order to write a comprehensive literature review. Finally, they will undertake an in-depth design study.

The research project is normally undertaken in collaboration with an industrial company, and could involve spending time at the sponsor's organisation; in the past this close contact has resulted in students being offered a job by the sponsor. Recent research topics have included work on racing car gearbox components, materials for artificial limbs, repair of composite structures, methods of bonding, spacecraft materials, damage mechanics and finite element modelling, performance of geodetic structures, and many others.

Author:
Dr John M Hodgkinson
Deputy Head
Centre for Composite Materials
Imperial College
South Kensington
London