A composite material is an assembly of two or more non-miscible materials (but which have a high capacity to adhere to each other). The new material thus constituted has properties that the two constituents alone do not have.
This phenomenon, which improves the quality of the material making it more suitable for a certain use (making it lighter, more rigid under an effort force, etc.), explains the growing use of composites in different sectors of industry. Nevertheless, the precise description of composites remains complex from a mechanical point of view.
A composite material consists of two materials, a reinforcement which provides mechanical strength and a protective matrix which is generally a plastic (thermoplastic or thermosetting resin) and which gives the structure its cohesion and transmits the efforts to the reinforcement. Today, there are a large number of composite materials which are generally categorised in three families according to the nature of the matrix:
- organic matrix composites (OMCs), which represent by far the largest volumes used in industry,
- ceramic matrix composites (CMCs), which are used only for very advanced applications at high temperatures such as space, nuclear and military applications, as well as braking (ceramic brakes)
- metal matrix composites (MMCs).
The main applications for composites are in air transport (civilian and military), maritime and rail transport, the building industry, aerospace and also sports and leisure, thanks in particular to their good mechanical strength compared to homogeneous materials like steel and their low density.
Fibreglass is used in making swimming pools in particular.
Carbon fibre used in aviation.
Plywood used in joinery, construction, cabinet making.
Plasterboard partitions, much used in construction for applications not exposed to the weather .
Reinforced concrete in civil engineering.
Aramid fibre (or Kevlar, which is a trade name) used for ballistic protection in bulletproof vests
GLARE, consisting mainly of aluminium and fibreglass, is used in aircraft construction