Repairing airplane wings with nanotubes in-flight

An electrical pulse through nanotubes and wires helps find the crack in an airplane wing while in-flight.

Researchers at Rensselaer Polytechnic Institute have come up with a way to detect potential structural problems with fighter planes while in flight, and in some cases repair them.

Carbon nanotubes in epoxy RPI

The technique, which is still experimental, involves applying an epoxy later infused with a wire grid and carbon nanotubes onto a wing or other structure. The epoxy is similar to the materials currently used to make fighter plane components. The wire grid and the nanotubes function as a communication network. Mechanics (or a computer) will shoot an electrical charge through the structure and measure how long it takes an electrical charge to go from two selected points.

If there is a crack in the structure, the crack will create electrical resistance. In that case, the signal will have to travel a longer distance to get around the crack. The extra time required to get from point A to point B serves as a signal that a potential problem exists. The picture shows carbon nanotubes randomly dispersed in an epoxy.

The cracks can also be repaired, depending on the material the wing is made of and other factors. When a crack is detected, voltage to the carbon nanotubes can be increased. This generates heat, which melts the epoxy that fills the crack in. In certain circumstances, the repaired wing will regain up to 70 percent of its original strength, according to RPI. That should keep you from plunging to your death.

The beauty of this method is that the carbon nanotubes are everywhere. The sensors are actually an integral part of the structure, which allows you to monitor any part of the structure," said Nikhil A. Koratkar, an associate professor in Rensselaer's Department of Mechanical, Aerospace & Nuclear Engineering, in a prepared statement. Koratkar was the principal investigator on the project.

A more detailed paper was published this week in Applied Physics Letters.

Nanotubes, which are stronger than steel, can also add structural integrity, depending on how they are integrated into a structure. General Motors puts multiwalled nanotubes into some car parts.

Angela Belcher at MIT (and co-founder of Cambrios Technologies) is working on a different technology for detecting flaws in metal aircraft parts. She is trying to develop genetically engineered microorganisms that will secrete proteins that will attach to specific metal alloys. Smear it on, the theory goes, and the luminescent protein will stick to areas undergoing abnormal amounts of stress.