This is a damn cool technology …
From the link:
The technique works like this. If a tiny hole/crack appears in the aircraft (e.g. due to wear and tear, fatigue, a stone striking the plane etc), epoxy resin would ‘bleed’ from embedded vessels near the hole/crack and quickly seal it up, restoring structural integrity. By mixing dye into the resin, any ‘self-mends’ could be made to show as coloured patches that could easily be pinpointed during subsequent ground inspections, and a full repair carried out if necessary.
This simple but ingenious technique, similar to the bruising and bleeding/healing processes we see after we cut ourselves, has been developed by aerospace engineers at Bristol University, with funding from the Engineering and Physical Sciences Research Council (EPSRC). It has potential to be applied wherever fibre-reinforced polymer (FRP) composites are used. These lightweight, high-performance materials are proving increasingly popular not only in aircraft but also in car, wind turbine and even spacecraft manufacture. The new self-repair system could therefore have an impact in all these fields.
(Hat tip: KurzweilAI.net)