Fibre-reinforced plastic (FRP) composite materials are basically of two types. The first type is short fibres reinforced in a plastic matrix, and the other type continuous (long) fibres reinforced in a plastic matrix. The exact distinction between a short and a continuous fibre is discussed in Chapter 1. Continuous fibre-reinforced composite materials are referred to by many labels: FRP composites, advanced composites, fibrous composites, composite materials or simply composites. These terms are now generally accepted to mean the same type of material, namely, continuous fibre reinforced in plastic. In this book, the term fibrous composites is used to define a continuous fibre reinforced in plastic. Fibrous composites are presently in use for a variety of structural applica- tions, and may offer an alternative to conventional metallic materials. The behaviour of fibrous composites subjected to a loading condition is very different from that of a metallic isotropic material. Therefore, 'new' analytical and testing methods are required to analyse a structural element and sections made from layered fibrous composites. There are a number of books written on the subject of composite materials. All of these are excellent in their content and achieve the authors' objectives.