Learn About Composite Materials

Fiberglass Cloth
Fiberglass cloth commonly used in composites. Todd Johnson

Definition

A "composite" is when two or more different materials are combined together to create a superior and unique material. This is an extremely broad definition that holds true for all composites, however, more recently the term "composite" describes reinforced plastics.

Background on Composites

The history of composites dates back to ancient times for construction applications; straw was mixed with mud to form a building material known as adobe.

The straw provided the structure and strength, while the mud acted as a binder, holding the straw together in place.

Since the days of adobe, the use of composites has evolved to commonly incorporate a structural fiber and a plastic, this is known as Fiber Reinforced Plastics or FRP for short. Like straw, the fiber provides the structure and strength to the composite, while a plastic polymer holds the fiber together. Common types of fibers used in FRP composites include:

  • Fiberglass
  • Carbon Fiber
  • Aramid Fiber
  • Boron Fiber
  • Basalt Fiber
  • Natural Fiber (Wood, Flax, Hemp, etc.)

In the case of fiberglass, hundreds of thousands of tiny glass fibers are compiled together and held rigidly in place by a plastic polymer resin. Common plastic resins used in composites include:

  • Epoxy
  • Vinyl Ester
  • Polyester
  • Polyurethane
  • Polypropylene

Examples of Composites

The most common example of a "composite" in a broad sense is concrete.

In this use, structural steel rebar provides the strength and stiffness to the concrete, while the cured cement holds the rebar stationary. Rebar alone would flex too much and cement alone would crack easily. However, when combined to form a composite, an extremely rigid material is created.

The composite material most commonly associated with the term "composite" is Fiber Reinforced Plastics.

This type of composite is used extensively throughout our daily lives. Common everyday uses of fiber reinforced plastic composites include:

  • Aircraft
  • Boats and marine
  • Sporting equipment
    (Golf shafts, tennis rackets, surfboards, hockey sticks, etc.)
  • Automotive components
  • Wind turbine blades
  • Body armor
  • Building materials
  • Water pipes
  • Bridges
  • Tool handles
  • Ladder rails

Benefits of Composites

In comparison to common materials used today such as metal and wood, composites can provide a distinct advantage. The primary driver and advantage in the adoption of composites are the lightweight properties. In transportation, less weight equates to more fuel savings and improved acceleration. In sporting equipment, lightweight composites allow for longer drives in golf, faster swings in tennis, and straighter shots in archery. While in wind energy, the less a blade weighs, the more power the turbine can produce. Besides weight savings, the most important benefits of composites include:

  • Non-corrosive
  • Non-conductive
  • Flexible, will not dent
  • Low maintenance
  • Long life
  • Design flexibility