New Technology Could Detect And Fix Cracks In Composites

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A simple new technique could help to identify and repair small, potentially dangerous cracks in high-performance aircraft wings made of composite materials, researchers at Rensselaer Polytechnic Institute, in Troy, N.Y., have reported. The scientists added a small amount of carbon nanotubes to the mix when forming composite materials from epoxy resin and carbon fiber. The tubes can electronically detect even the tiniest cracks and then release materials that will repair the problem, with a 70-percent recovery in strength. The process would improve the life span, integrity and safety of composites, the researchers said. "What's novel about this application is that we're using carbon nanotubes not just to detect the crack, but also to heal the crack," said principal scientist Nikhil Koratkar. "We use the nanotubes to create localized heat, which melts the healing agent, and that's what cures the crack."

Koratkar said he envisions the new system for detecting cracks to eventually be integrated into the built-in computer system of a fighter jet or other composite aircraft. He also said there is some evidence that the nanotube structures help to prevent cracks in the first place. He plans further studies. Philip Irving, an expert in damage tolerance at Cranfield University in the U.K., told New Scientist that heating could weaken a composite. "The top surface of a wing may buckle," he warned.