Modern aerospace is driven by the singular, relentless pursuit of optimizing the strength-to-weight ratio of its construction materials. Gone are the days when aluminum dominated the skies. That was the 20th century. The 21st century belongs to aviation composites. Composite materials offer strength-to-weight ratios aluminum and steel cannot even touch.
We have been in business long enough to have witnessed the transition of aviation composites from minor contributions to primary structural components in some of the world’s most advanced aircraft. Take the Boeing 787 Dreamliner and the Airbus A350. Neither aircraft would fly today without a heavy dose of composite materials.
It should be noted that the composite category is not a monolith. Rather, it is sophisticated selection of highly engineered materials that can be tailored to just about any need. From specific stresses to harsh aviation environments and temperature extremes, properly engineered composites can handle it all.
Here are the four primary composites utilized by the aerospace and aviation industries:
Carbon fiber reinforced polymers (CFRPs) are the gold standard of performance in aviation composites. So much so that when most people think of aviation composites, they think of carbon fiber. A CFRP is composed of surprisingly thin carbon filaments woven into a fabric and embedded in a resin matrix. That matrix is epoxy more often than not.
CFRPs dominate aviation composites for three very good reasons:
We like to say that CFRPs rule the skies because they are used so extensively in aviation design. They are the material of choice for fuselage sections, wing spars, and tail assemblies. Some of the biggest and most impressive jets now occupying the skies are made of over 50% CFRPs (by weight).
What people often refer to as fiberglass is actually a glass fiber reinforced polymer (GFRP). A GFRP is like a CFRP in principle. Thin glass fibers are used to create a fabric that is then embedded within a resin matrix. GFRPs were among the first aviation composites adopted globally. While they are not as stiff as CFRPs, they still possess unique properties that make them attractive in aviation and aerospace design.
Here is what GFRPs bring to the table:
The aviation industry relies on GFRPs to build components like wing tips and radomes. Inside a typical commercial aircraft, there is a healthy amount of fiberglass in floor panels, overhead luggage bins, etc.
The third primary composite used by aerospace and aviation designers is the aramid fiber composite. You might be familiar with the Kevlar brand name. Aramid fibers are organic fibers known for exceptional toughness and thermal stability. Engineers consider them the ‘protector’ class of composites.
They are used in aviation design thanks to the following three properties:
Engineers look to aramid fiber composites when designing engine cowlings, cargo hold panels, and a variety of leading-edge surfaces. Though commercial aircraft passengers do not readily see the material, it does its job to keep them safe and comfortable in the skies.
The fourth primary composite is a category of composites known as ceramic matrix composites (CMCs). Among the many things that make CMCs unique is the reliance on a ceramic matrix rather than resin. A CMC is essentially a layer of ceramic fibers embedded in a ceramic matrix.
CMCs are considered the ‘new frontier’ of aviation composites because they are still relatively new. Their main selling point is their ability to withstand temperatures that would melt polymers and metals. Here is what engineers get when they select CMCs:
CMCs are perfectly suited for designing turbine blades, combustion chamber liners, and exhaust nozzles. They make it possible to build bigger engines that run hotter and produce more thrust.
Modern aviation would not be what it is today without these four aviation composites. Here at Aerodine, we are a proud supplier of aviation composites and related materials. Supporting aviation and aerospace is a big part of what we do.
Why have aviation composites all but replaced aluminum an aircraft design?
A higher strength-to-weight ratio is the most attractive characteristic composites offer. Air frames can be lighter but still be stronger.
How do aviation composites handle lightning strikes?
Composites do not conduct electricity very well. So to protect aircraft, a thin copper or aluminum mesh is integrated into a composite skin.
How are internal flaws in composite materials handled?
Engineers must rely on non-destructive testing to detect internal flaws that cannot be seen with the naked eye. Early detection leads to effective repairs.
How easily do composite materials fatigue?
Composites offer excellent fatigue resistance. They do not develop the microscopic cracks metals are known for after being subjected to repeated vibration and pressure cycles.
What are the temperature limits for polymer-based composites?
Where CMCs can operate at temperatures exceeding 2,200°F, most carbon and glass fiber composites tap out at just under 400°F.
Are aviation composites more expensive than metals?
Initially, materials and manufacturing labor command a higher price tag. But a superior total life cycle ultimately lowers the cost.
