Engineers at the Massachusetts Institute of Technology (MIT) have developed a method to use carbon nanotubes to produce aerospace-grade composites without an autoclave, researchers announced in a paper published yesterday in the journal Advanced Materials Interfaces. “If you’re making a primary structure like a fuselage or wing, you need to build a pressure vessel, or autoclave, the size of a two- or three-story building, which itself requires time and money to pressurize,” said MIT professor of aeronautics and astronautics Brian Wardle. “These things are massive pieces of infrastructure. Now we can make primary structure materials without autoclave pressure, so we can get rid of all that infrastructure.”
A team led by MIT post-doctoral student Jeonyoo Lee created a method to make aerospace-grade composites without requiring an oven to fuse the materials together. The team wrapped layers of material in an ultrathin film of carbon nanotubes that, when electrified, generated enough heat to cure and fuse them together. As a result, the team produced composites as strong as those made in a conventional aircraft autoclave but only using 1 percent of the energy.
Next, the team will look for ways to scale the process for curing large sections of composites that would be used for primary aerostructures to generate enough pressure to fill any void between the layers of materials. They’ve successfully done that in the lab with very small samples. “There are ways to make really large blankets of this stuff, and there’s continuous production of sheets, yarns, and rolls of material that can be incorporated in the process,” Wardle added.
Engineers at the Massachusetts Institute of Technology (MIT) have developed a method to use carbon nanotubes to produce aerospace-grade composites without an autoclave, researchers announced in a paper published last month in the journal Advanced Materials Interfaces. “If you’re making a primary structure like a fuselage or wing, you need to build a pressure vessel, or autoclave, the size of a two- or three-story building, which itself requires time and money to pressurize,” said MIT professor of aeronautics and astronautics Brian Wardle. “These things are massive pieces of infrastructure. Now we can make primary structure materials without autoclave pressure, so we can get rid of all that infrastructure.”
A team led by MIT post-doctoral student Jeonyoo Lee created a method to make aerospace-grade composites without requiring an oven to fuse the materials together. The team wrapped layers of material in an ultrathin film of carbon nanotubes that, when electrified, generated enough heat to cure and fuse them together. As a result, the team produced composites as strong as those made in a conventional aircraft autoclave but only using 1 percent of the energy.
Next, the team will look for ways to scale the process for curing large sections of composites that would be used for primary aerostructures to generate enough pressure to fill any void between the layers of materials. They’ve successfully done that in the lab with very small samples. “There are ways to make really large blankets of this stuff, and there’s continuous production of sheets, yarns, and rolls of material that can be incorporated in the process,” Wardle added.
There are many advantages to making fuselages from composites rather than aluminum, including weight savings of up to 50 percent. Composites are also more flexible and handle turbulence better than aluminum. Single-piece structural assemblies are stronger, have better impact resistance, and are easier to assemble. The greater strength also enables more robust pressurization systems, significantly reducing the cabin altitude and greatly improving passenger comfort. The higher oxygen content of a lower cabin altitude also reduces passenger fatigue. Aluminum airliners typically have a cabin altitude of as high as 8,000 feet at their cruising altitude. The composite-fuselage Boeing 787 Dreamliner, however, maintains a cabin altitude of 6,000 feet at its cruising altitude.
Composite structures are also non-corrosive, which enables higher humidity levels on board. The low moisture content needed to sustain aluminum structures—as low as 5 to 10 percent relative humidity—can be very uncomfortable over time. Low humidity dries out nasal passages, reducing the protective moisture of the mucous membranes and making passengers more vulnerable to germs. Also, in a very dry environment, viruses are able to survive much longer, floating around in the air and increasing the chance of infection.
If the MIT project ultimately leads to greater availability of composites in major aircraft structural assemblies, the weight savings, alone, could significantly improve efficiency and reduce emissions.