ABSTRACT

The combination of two or more different materials to form a new material with improved material properties has been well known for decades. This class of materials with enhanced material properties is known as composite materials and these are being widely used in the design of various types of structural elements. Some of the more common fibers used in composite material fabrication are boron, glass, graphite, and aramid, although other reinforcements such as aluminum, boron nitrate, berylium, silicon carbide, silicon nitride, titanium, and tungsten are also in use. The matrix materials that are commonly used are epoxy, phenolics, and polyimides. The composite material that is formed by combining the matrix and fibrous elements may have different structural properties due to the forming and the processing methods used in the process. Among the composite material types, the fiber-reinforced or filamentary type, that is, those material systems that consist of selected fiber macroconstituents are most widely used. Such composite materials have the desirable properties of high stiffness-to-weight ratio as well as being light. In addition, the composite material property can be improved by variation of the fiber orientation and stacking sequence of the layer of the composite material. This added feature provides the designer a degree of flexibility that is extremely valuable. For a complete discussion on the micromechanics and macromechanics aspects of composite materials, the reader is referred to a wealth of information available on this topic in the literature.