Overview of Reinforcement Fibres

Materials in the form of filaments could possess very high strength and stiffness. The figure below, is showing, how the strength of a carbon-fibre decreases as the diameter of the fibre increases.

However, fibres are not directly usable in engineering applications, and are, therefore, embedded in a matrix as reinforcement. The matrix binds the fibres together, transfer loads to the fibres, and protect them from environmental attack and handling. Morphologically, there are two main classes of fibrous composites: continuous (long fibre) and discontinuous fibre (short fibre). Continuous fibres have much better stiffness and strength, but is more difficult to manufacture. Also, continuous fibres impart anisotropy on a composite lamina in the fibre direction - hence, by changing the orientation of the reinforcement the laminate (stack of lamina) could be designed in such a way that the structure becomes stronger along the direction of loading. Cases where the loading direction is random, short and discontinuous fibres randomly oriented in the matrix is preferred which gives an improved strength and stiffness along any direction.

From the material point of view, there are two major groups of fibres - organic and inorganic fibres. Examples of inorganic fibres are Glass fibre, Boron fibre and Ceramic fibres. Organic fibres include Carbon fibre, Polyaramids like Kevlar and Polyethylene. Let us have an overview of these fibres.