Aerospace composites are one subgroup of a much larger group of materials that have revolutionized manufacturing over the last five or six decades. They are also specialized composites intentionally designed to withstand the rigors of aerospace applications. Much of what they offer is directly related to their fiber reinforcements.
Fiber reinforcement is just one ‘ingredient’ in an aerospace composite. When combined with the other components, fiber reinforcements offer substantial properties that make them incredibly attractive to aerospace design. But what role do they play, exactly? Let us find out.
A composite is a material produced by combining two or more materials with the properties that engineers desire for a particular application. The materials are combined at a macroscopic level. Furthermore, combining them enhances the properties so that the composite is superior to its component materials.
What is commercially referred to as carbon fiber is the perfect example. Small fibers of carbon are combined with a resin matrix to form what the industry refers to as a carbon fiber reinforced polymer (CFRP). To your typical consumer, it appears to be just another plastic. But it is so much more.
The chosen fibers in a composite play a key role. They add strength and stability, for instance. More specifically, the role they play in aerospace composites is demonstrated in three key functions:
Much like rebar in concrete, reinforcing fibers carry most of the applied loads in a composite structure. The composite resin matrix binds the fibers together. It also transfers energy between the fibers for more consistent load-bearing capabilities.
The load-bearing capacity of a particular composite is observed in its tensile strength and rigidity. Simply put, carbon fiber offers more tensile strength and rigidity than both steel and aluminum. That’s why it has all but replaced aluminum in modern passenger aircraft.
The relationship between fiber reinforcements and resin matrices lies in a superior strength-to-weight ratio compared to steel and aluminum. This allows designers to create components that are much stronger than their aluminum and steel counterparts – yet lighter at the same time. Some of the most interesting aerospace designs of the 2020s would not be possible without fiber reinforced polymers.
Fiber reinforcements allow engineers the flexibility to design complex geometries that just cannot be effectively reproduced with steel and aluminum. But without fibers reinforcing complex components, strength and stability would be compromised.
In theory, engineers could use just about any type of fiber to reinforce a composite material. But practical application limits their choices. Here are the three most common fibers and the properties of each that engineers appreciate:
It is common for aerospace designers to incorporate multiple fiber reinforcements in a single design. A typical spacecraft is built using a combination of carbon fiber, fiberglass, and aramid fiber components.
One could make the case that composites and their fiber reinforcements are the lifeblood of modern aerospace. Aerospace composites are responsible for getting us to the moon and back. They have contributed to space exploration, space-based defense, and so much more. And we owe their success to fiber reinforcements.
