fracture

The horse, a classic model of grace and speed on land, is now an unlikely source of inspiration for more efficient flight. So says a group of University of Florida engineers who have recreated part of a unique bone in the horse’s leg with an eye toward lighter, stronger materials for planes and spacecraft.
The third metacarpus bone in the horse’s leg supports much of the force conveyed as the animal moves. One side of the cucumber-sized bone has a pea-sized hole where blood vessels enter the bone. Holes naturally weaken structures, causing them to break more easily than solid structures when pressure is applied. Yet while the third metacarpus does fracture, particularly in racehorses, it doesn’t break near the hole – not even when the bone is subjected to laboratory stress tests. UF engineering researchers think they’ve figured out why – and they’ve built and are testing a plate that mimics the bone’s uncanny strength in a form potentially useful for airplanes and spacecraft.