A self-healing composite

When a wind turbine blade or an airplane is hit by something, the damaged part has to be either replaced or patched with resin. Replacing the part is expensive, while repairing it with resin can make it heavier and change its properties. But now, thanks to a new, patented technology, researchers at EPFL have found a way to quickly and easily repair cracks in composite structures.

“With our technology, a repair agent is incorporated in the composite material,” says Amaël Cohades, a researcher at EPFL’s Laboratory for Processing of Advanced Composites(LPAC). Cracks in the resin can be repaired on site in little time by simply heating the material to 150°C. The heating process activates the repair agent, and the damaged part quickly heals, without any change to the original properties. This new-to-the-market technology can be applied to all sorts of structures, extending their lifespan at least threefold.

The material’s properties and initial crack resistance are the same as those of traditional composites. What’s more, the technology is compatible with current manufacturing processes, so production facilities do not need to be retooled.

This technology could be particularly useful for wind turbines and storage tanks. “The cost of maintaining the world’s wind turbines alone is estimated at 13 billion Swiss francs in 2020,” says Cohades. He says the technology could also be applied to “many parts that we don’t bother to repair at present, like bikes and car bumpers.” One limitation is that the material doesn’t heal if the impact breaks the fibers. But since the resin is always damaged first, this heat-based self-healing system would still work in the majority of cases.

A prototype on display at the World Composites Show

Thanks to an EPFL enable grant, designed to help EPFL scientists move their ideas out of the lab, the researchers were able to create a standard aerospace prototype. This part, made from fiberglass-reinforced resin, demonstrates how the healing process works. It will be presented at the JEC World Composites Show in Paris from 12 to 14 March 2019. In addition, the researchers are now setting up a startup to market the new materials.

(Sarah Aubort)