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Self-Healing Composites For Aircraft: Skeleton Force

The body of the Eurofighter jet is made primarily from fibre reinforced polymer (FRP) composites; lighter, stronger, and stiffer than metallic counterparts. The result is a much more fuel-efficient aircraft. However, fibre reinforced composites lack the ductility of metals. The fibre-reinforcement is planar in nature so that shocks cannot be absorbed and dissipated by the material. Aircraft panels can suffer from barely visible impact damage (BVID), notoriously difficult to diagnose but ruinous to mechanical performance.

Dr. Richard Trask and his coworkers at the University of Bristol believe that the answer is to build self-healing behavior into the composites. How? By looking to the example of bone. Human bone is also a composite material composed of brittle elements in layered structures. However, on cracking, human bone can remodel to retain mechanical strength while a FRP element must be repaired or replaced. The remodelling is carried out by two types of bone cells, osteoclasts and osteoblasts. The osteoclasts can resorb bone; they create a tunnel or vascule in the dead bone. A blood vessel follows along this vascule to the damage site, bringing osteoblasts which make the new bone.

The Bristol team incorporated a vasculature system into fibre reinforced polymer laminates via a “lost wax” process. On damage, a healing resin could be infused through the channels. They found that, after self-healing, the compression strength recovered to 97% of that pre-impact.

The development of such self-healing mechanisms in synthetic materials will have beneficial effects throughout the world of engineering.

http://www.materialsviews.com/details/news/1249211/Self-Healing_Composites_For_Aircraft_Skeleton_Force.html