We normally think of aerospace composites as lightweight materials that allow manufacturers to build larger, lighter aircraft capable of withstanding considerable punishment. But there is another side to the composite equation. It has less to do with higher performance and more to do with keeping people comfortable.
Aerospace composite materials can be designed in such a way as to contribute to noise reduction. The secret lies in vibration dampening and sound absorption. By leveraging the unique physical properties of certain types of composites, aircraft passengers enjoy a more pleasant flight thanks to reduced airborne and structure-borne noise.
There are two big things that can make flying uncomfortable from an audible perspective. First is the actual noise generated by engines, equipment, and the process of an aircraft moving through the air. Second are the vibrations the aircraft is subject to. Both can make for an uncomfortable experience.
Certain types of laminated composite panels and honeycomb structures can significantly reduce aircraft noise. They are designed with embedded acoustic features that absorb sound while still maintaining a light weight.
In terms of vibration dampening, we rely on advanced reinforced polymers combined with the right fibers – like aramid fiber, for example. The right combination of polymer and fiber creates a material that more effectively dampens vibrations to reduce both structural and engine noise.
Aerospace composites allow us to do a lot of things acoustically that simply are not possible with more traditional materials. For example, we can design lightweight insulation and noise-dampening materials that are then deployed for manufacturing secondary structures and interior panels.
Composites also lend themselves well to the design of customized solutions, including hybrid materials. We can exercise precise control over how vibrations travel through materials, thereby engineering both materials and parts for maximum noise attenuation. And we can do this throughout an aircraft’s entire structure, including the fuselage, engine, and even gear assemblies.
The key to maximizing noise reduction with aerospace composites is material design. A good engineer looks at each application and designs specifically for it. One application might call for a specific fiber, while another requires a more specialized manufacturing process.
For example, a lower density and stiffer composite should decrease impact forces while encouraging more efficient energy dissipation during dynamic loading. The result should be a reduction in both noise intensity and transmission. We can achieve both lower density and stiffer composition with the right choice of materials.
Elsewhere in the aircraft, panels made with open-cell foams and vibration-dampening layers more effectively suppress cabin noise. Using the same panels in other parts of the plane can reduce the amount of machine noise transferred from the aircraft’s mechanics into the cabin.
Noise reduction is a priority for commercial passenger aircraft. It is less of a concern for cargo and military aircraft. Nonetheless, there is a material for every noise reduction application. And it’s a composite that often makes the difference.
Advanced composites are critical to more important aspects of aerospace design including thermal resistance, weight, and structural integrity. But we are fortunate in that composites can also be designed to absorb noise and dampen vibrations. Noise reduction is so effective in the 2020s that quiet conversations with seatmates are the norm.
Next time you fly, consider how much of the aircraft comprises composite materials. Give some consideration to the fact that your flight is quieter than anything passengers experienced 50 years ago. Your comfort in the noise department is directly related to the advanced aerospace composites companies like ours produce.
