Advanced Composites
A Technical Overview

Our discussion begins with a definition of Advanced Composites; Advanced Composites are generally understood to be materials consisting of a polymer matrix reinforced with high-strength continuous fibers of a predefined orientation.

To put the definition in simplified terms, every composite has at least two components; reinforcement and a matrix. The reinforcements are typically fibers, particles or flakes. The matrix in most common cases is a resin system or adhesive that binds the reinforcements together. The reinforcement material and the matrix are combined at a macroscopic level where the reinforcement is immersed in the matrix. The two materials bond conjointly to make one system that is commonly referred to as a Composite.

As an example, manufactured particleboard and concrete are considered composite materials. Particleboard consists of wood chips (the reinforcement) bound together with an adhesive (the matrix). Furthermore, Concrete is made up of cement (the matrix) and particles of sand or gravel (the reinforcement). Although particleboard and concrete are a known as composite materials, they are not considered to be an "Advanced" Composite.

As emphasized in the above definition, the continuous fibers (the reinforcement) of a predefined orientation are the key design requirements for a composite to be considered an Advanced Composite. As an example, a fiberglass shower stall is considered a Fiber Composite and is a bit more complex than say particleboard and concrete, but it is not considered to be an Advanced Composite. The reinforcement in the particular case of a fiberglass shower stall is short discontinuous glass fibers that have been chopped to random lengths and diameters and encapsulated within a resin system. Although the random placement of the discontinuous glass fibers provide good strength properties, it does not allow the designer to take full advantage of the properties and performance of the glass fiber as one may achieve if the fiber was encapsulated as one long continuous fiber.

Advanced Composites offer several advantages over conventional composite materials. Some basic advantages are high strength and stiffness, exceptional strength to weight and stiffness to weight ratios, dimensional stability, improved fatigue strength and impact resistance, and corrosion resistance.

Advanced Composites also offer the ability to tailor the mechanical performance of the material to the particular application by predefining the orientation of the fiber within the matrix.

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