Healing the cracks

Aerospace engineers at Bristol University have developed a new technique to mimic healing processes found in nature, which could enable damaged aircrafts to mend themselves automatically.

The technology works so that if a tiny hole or crack appears in the aircraft, epoxy resin would ‘bleed’ from the embedded vessels to 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.

It has the potential to be applied wherever fibre-reinforced polymer (FRP) composites are used, such as in the manufacture of wind turbines and spacecrafts. The technique fills hollow glass fibres contained in FRP composites with resin and hardener. If the fibres break, the resin and hardener ooze out, enabling the composite to recover up to 80-90 per cent of its original strength, comfortably allowing a plane to function at its normal operational load.

By further improving the safety characteristics of FRP composites, the self-healing system could encourage even more rapid uptake of these materials in the aerospace sector. A key benefit would be that aircraft designs including more FRP composites would be significantly lighter than the primarily aluminium-based models currently in service. A small reduction in weight equates to substantial fuel savings over an aircraft’s lifetime.

The new self-repair technique developed by the EPSRC-funded project could be available for commercial use within around four years.