Page 32 - Using ANSYS for Finite Element Analysis Dynamic, Probabilistic, Design and Heat Transfer Analysis

ChaPter 2

comPosite materials

2.1 ComPosites—a BasiC introduCtion

Composite materials have been used in structures for a long time. In recent
times, composite parts have been used extensively in aircraft structures,
automobiles, sporting goods, and many consumer products. Composite
materials are those containing more than one bonded material, each with
different structural properties. The main advantage of composite materials
is the potential for a high ratio of stiffness to weight. Composites used for
typical engineering applications are advanced fiber or laminated compos-
ites, such as fiberglass, glass epoxy, graphite epoxy, and boron epoxy. To
fully appreciate the role and application of composite materials to a struc-
ture, an understanding is required of the component materials themselves
and of the ways in which they can be processed; this article therefore looks
at basic composite theory and properties of materials used.
In its most basic form a composite material is one that is composed of at
least two elements working together to produce material properties that are
different to the properties of those elements on their own. In practice, most
composites consist of a bulk material (the “matrix”), and a reinforcement
of some kind, added primarily to increase the strength and stiffness of the
matrix. This reinforcement is usually in fiber form. Today, the most com-
mon man-made composites can be divided into three main groups:

• Polymer matrix composites (PMCs)—These are the most common
and will be discussed here. Also known as FRP—fiber-reinforced
polymers (or plastics)—these materials use a polymer-based resin
as the matrix, and a variety of fibers such as glass, carbon, and
aramid as the reinforcement.
• Metal matrix composites (MMCs)—Increasingly found in the
automotive industry, these materials use a metal such as aluminum
as the matrix, and reinforce it with fibers such as silicon carbide.