Composite materials as the name suggest are the combination of different materials.
However, what types of materials need to be combined to be formally called composite materials. What are the main types of composites, and how are they made?
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Composite materials are formed by combining two or more materials with different properties. In composites, all materials combined physically can be differentiated chemically.
The objective of combining different materials is to get more desirable properties. The composite materials give unique properties which are different from their constituents and gives the synergic effect to their constituents.
They are the multiphase materials which exhibit a significant portion of all the properties present in different phases in it. For instance, fibres are usually strong, and polymers show better stiffness. By combining them in a composite material gives both properties to the new material, i.e. better stiffness and high strength.
Engineering or commercially available composites are usually manufactured from straight fibres like glass fibres, carbon fibres and aramid fibres. These fibres are set in a host of polymer matrices like polyester, epoxy, acrylic or phenolic resins to manufacture composites.
There are various methods to manufacture composite structures. These processes are designed to meet specific design requirements. Selection of specific manufacturing process for composite parts depends on the raw materials, design specification and end-use application.
All of the fabrication methods of composite parts require moulding process to give shape to the resins and reinforcements. The most common technique of composite fabrication is hand layup. In this technique, fibres are stacked in the moulds, and then resins are applied to them by hand.
In some high-performance composite components, pressure moulding is performed with the help of vacuum bagging or some other techniques. In some applications, high temperature is required along with the pressure for curing of resins. Autoclaves are used to meet that requirement.
Filament winding is the most common method in the industry to fabricate the cylindrical parts. In this technique, the filament is continuously winded along with the infusion of resins on the cylindrical moulds.