Carbon-fibre-reinforced polymers are now the preferred composite materials as they provide low weight and high strength with cost savings – a particularly attractive combination for the airline industry.
The EU-funded project IMS&CPS has contributed to this advance by developing a new closed-mould manufacturing technology that produces integrated components. This integration allows manufacturers to eliminate a number of metallic parts – with the aim of reducing aircraft weight and manufacturing costs.
The team also created a pure carbon nanotube fibre fabric and a pure carbon nanotube yarn. Numerical models developed by the team allow the integration of these materials within polymers.
The pure carbon nanotube fibre fabric is likely the first of its kind, says Emmanuel Detaille of project coordinator Coexpair in Belgium.
“Around 998 million passengers travelled by plane in 2010, compared to 262 million in 1989,” he adds. “In 2008, 25 million tonnes of kerosene were consumed for intra-European flights alone. We wanted to provide an effective answer to the issue of global energy by proposing technologies to decrease an airplane’s total weight and thus fuel consumption.”
The carbon nanotube potential
Conventional carbon fibres are five to ten micrometres in diameter and made of carbon atoms in a crystal lattice. They have been successfully produced for commercial use, particularly in the aircraft industry, since the 1960s.
But new possibilities appeared with the discovery of carbon nanotubes. These tube-shaped carbon molecules, with diameters in the range of nanometres or billionths of a metre, have unusual properties, including high electrical conductivity, making them very useful in a variety of electrical and mechanical applications.
For example, used in aircraft wings, the conductivity of carbon nanotubes could help provide protection against lightning strikes. This use would reduce weight compared to the metallic parts currently used for such components – such as copper mesh.
As a demonstration of their work, the researchers produced two sections of an aircraft: a small part of fuselage panel and a re-engineered nose landing gear door.
“The ‘Same-Qualified-Resin-Transfer-Molding’ (SQRTM) process can be used to produce a one-shot complex structure,” adds Detaille. “This integration allows us to eliminate a number of metallic parts and reduce weigh.”
IMS&CPS also studied different ways of integrating carbon nanotubes into composite materials. The studies resulted in database on mechanical, electrical and fire properties for use by researchers and industry.
The results of the project are expected to help manufacturers reduce the cost, weight and fuel consumption of new aircraft. Energy consumption will also be lower during manufacturing, because fewer parts need to be produced separately.
“The results support the development of a strong European expertise in both innovative materials development and composites materials manufacturing,” adds Detaille.
Since the end of the project in September 2013, the participating companies have moved forward with a large-scale manufacturing programme based in part on the results from IMS&CPS.