UV light illustrates how the epoxy resin bleeds into a fracture
You may have heard about about Greece’s self-healing house, now aerospace engineers at Bristol University have applied the concept to the development of self-repairing aircraft.
The system involves filling the hollow parts of composite-based aircraft with a hardening epoxy resin, which “bleeds” out of any hole or crack that forms on the craft and patches it up on the fly. The resin allows the composite to recover 80-90% of its strength, more than enough to ensure a safe flight home, where it can then be properly repaired. The researchers claim the technology could be commercially available within four years.
The process bears a striking resemblance to the human healing system, where injuries trigger an automatic bleeding/scabbing response. Like blood, the resin is even colored, (in blue rather than red, however), to allow mechanics to easily pinpoint areas of self-reparation on the ground. In time, the researchers hope to bring the technology even closer to the human body, by allowing the healing agent to move through an integrated vascular network built into the body of the plane, just like the circulatory systems of animals.
The technology can be applied to any plane that incorporates fiber-reinforced polymer composites – the 787 Dreamliner and Bombardier Learjet being two examples. Composite structures are significantly lighter than aluminum-frame models, increasing fuel efficiency and reducing carbon emissions. The Bristol University researchers, who are funded by the Engineering and Physical Sciences Research Council, believe the added safety provided by the epoxy system will speed up the adoption of composite materials by the airline industry. The epoxy could also be used in other structures that use composite materials – including some cars, wind turbines and spacecraft.
“This approach can deal with small-scale damage that’s not obvious to the naked eye but which might lead to serious failures in structural integrity if it escapes attention,” says Dr Ian Bond, who has led the project. “It’s intended to complement rather than replace conventional inspection and maintenance routines, which can readily pick up larger-scale damage, caused by a bird strike, for example.”
While the epoxy resin provides a revolutionary solution for small-scale repairs, an entirely different approach to self-repairing aircraft that facilitates large-scale airborne maintenance has been proposed by designers at Aurora Flight Sciences. The Odysseus is a solar-powered, modular craft that can change shape while in flight, and enables the replacement of one of its three segments if damage occurs.
Link to Bristol University