The Science and Technology of Composite Materials

In an advanced society like ours we all depend on composite materials in some aspects of our lives. Fiberglass developed in the late 1940s was the first modern composite and is still the most common. It makes up about 65 per cent of all the composites produced today and is used for boat hulls, surfboards, sporting goods, swimming pool linings, building panels and car bodies. You may well be using something made of fiberglass without knowing it.

Composite materials are formed by combining two or more materials that have quite different properties. The different materials work together (1) to give a composite unique properties but within the composite you can easily tell the different materials apart – they do not dissolve or blend into each other.

The greatest advantage of composite materials is strength and stiffness combined with lightness. By choosing an appropriate combination of reinforcement and matrix material, manufacturers can produce properties that exactly (2) fit the requirements for a particular structure for a particular purpose.

Modern aviation, both military and civil, is a prime example. It is worth remembering that composites are less likely than metals (such as aluminium) to break up completely under stress. A small crack in a piece of metal can spread very rapidly with very serious consequences (especially in the case of aircraft). The fibers in a composite act to block the widening of any small crack and to share the stress around.

The right composites also (3) withstand heat and corrosion. This makes them ideal for use in products that are exposed to extreme environments, therefore they are naturally more durable.

Another advantage of composite materials is that they (4) provide design flexibility. Composites can be either (5) moulded or sintered into complex shapes – a great (6) asset when producing something like a surfboard or a boat hull.

The downside of composites is usually their cost. Although manufacturing processes are often more efficientwhen composites are used, the raw materials are still expensive.

11. Which of the following is not true? Correct the false statements.

1. Fiberglass is one of the latest composites.

2. Composite materials are formed by combining two materials that have the similar properties.

3. Composite materials can combine more than two materials.

4. Composite materials is absolutely new class of materials.

5. Modern aviation wouldn’t be much more efficient without composites.

6. The fibers in a composite are not capable to block the widening of a small crack but only share the stress around.