Mechanical Behaviour of Composites

The reinforcing filler usually takes the form of fibres but particles (for example glass spheres) are also used. A wide range of amorphous and crystalline materials can be used as reinforcing fibres. These include glass, carbon, boron, and silica. In recent years, fibres have been produced from synthetic polymers-for example, Kevlar fibres (from aromatic polyamides) and PET fibres. The stress-strain behaviour of some typical fibres is shown in Fig. 3.2. 

Glass in the form of fibres is relatively inexpensive and is the principal form of reinforcement used in plastics. The fibres are produced by drawing off continuous strands of glass from an orifice in the base of an electrically heated platinum crucible which contains the molten glass. The earliest successful glass reinforcement had a calcium-alumina borosilicate composition developed 

During production the fibres are treated with a fluid which performs several functions. 

This treatment is known as sizing. As mentioned earlier, the joint between the matrix and the fibre is critical if the reinforcement is to be effective and so the surface film on the glass ensures that the adhesion will be good. 

---

Mechanical Behaviour of Composites Directly by matrix manipulation = 1.318 X 10" or by multiplying out the terms... 

Mechanical Behaviour of Composites Overall Stiffness Matrix Q(0) = T- Q T,... 

---