A recent article in the Science Daily details a 3-year research project ‘Bleeding Composites; Damage Detection and Repair Using a Biomimetic Approach’. Incredibly, within 5 years aircraft may be able to mend themselves, even in flight.
It works something like this. If a tiny hole or crack appears in the airplane (maybe due to wear or fatigue), epoxy resin would ‘bleed’ from embedded vessels near the damage and seal it up, sort of like a scab. Dye added to the resin would mark the ‘self repairs’ for future ground inspections so more permanent repairs could be made.
Hollow glass fibres contained in the FRP composite material would be filled with resin and hardener. When the fibres break, the resin and hardener would ooze out creating the “scab”. The repairs are expected to result in recovery of 80%-90% of the original strength of the material and would occur automatically as the damage ocurred, even in flight.
According to Dr. Ian Bond, who has led the project, “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. 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.”
This technique which mimics the natural bruising/bleeding/healing processes of our own bodies has been developed by aerospace engineers at Bristol University. This new technique can be used wherever fibre-reinforced polymer (FRP) composites are used. These materials are increasingly popular for use in aircraft, automobiles and even spacecraft.
One important benefit may be aircraft designs using more composite materials in place of aluminum. The resulting reduction in weight could lead to substantial fuel savings over the coarse of an airplanes lifetime. In aircraft FRP composites can be used in any part of the fuselage, nose, wings, and tailfins.
This new self-repair technique may be availble for commercial use within 4-5 years.