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Fiber Reinforcements

Updated: Nov 16, 2021

Composite components are made up of 2 or more individually recognizable components, but advanced composites only utilize 2 main ingredients: fiber reinforcement and polymer matrix. Fibers are the main component in composite structures as they provide the strength, durability, and flexibility of the final component. Read this blog for more in-depth information on the different types of fibers and their available configurations.

A fiber is defined as a material that has a long axis, usually many times greater than its diameter. The way fibers, but especially short fibers, are defined is by their aspect ratio. The aspect ratio refers to the fiber length divided by its diameter (l/d), and in order to be considered a fiber, the material usually will have an aspect ratio greater than 100.

As we discussed in Intro to Composites, an individual strand of fiber can be thought of as a rope, where it has really high tensile strength but really low compressive strength. When combined with the polymer matrix, the resulting part is extremely strong and lightweight. As technology develops and the need for more environmentally friendly practices forges ahead, the availability of fiber reinforcements is ever-expanding. However, there are three main types of fiber reinforcements: glass, carbon, and natural.

Glass Fiber

Incorporating glass fiber with a polymer matrix in the 1930s was really the beginning of modern-day advanced composites, resulting in a common product known as fiberglass. Fiberglass is used in everyday items such as metro seats, fair rides, and sailboats to name a few.

Fig. 1: Fiberglass Product Examples

It is not as strong or as stiff as carbon fibers, but it has other characteristics that make it desirable in many applications. It is considered an insulator and is invisible to most types of transmissions, making it a good choice for electrical or broadcasting applications.

The main benefits of using fiberglass over metals are primarily the cost, but also the significant weight savings, which is important in transportation and recreation applications. Fiberglass is cheap, lightweight, and has good structural integrity. This is why fiberglass is so common in household, recreational, and transportation equipment.

Carbon Fiber

Carbon fiber is even stronger and lighter than fiberglass, but these benefits are reflected in the increase in cost, hence why it is most common in aerospace or high-end competition equipment. Ever since its creation in the 1960s, it has been revolutionizing industries such as aerospace, motorsports, and professional equipment, creating very strong and very lightweight components. Some examples of carbon fiber components are in Formula 1 cars, planes, and hockey sticks.