Woodpeckers are uniquely unsusceptible to head trauma: Despite pecking 12,000 times per day at a speed of 23 feet per second for each peck (which they do to knock bugs out of trees for food, as well as to make hollow spaces for their nests), a healthy woodpecker won't experience any of the cracked skulls or brain damage that would befall a human who suffered so many hits to the head. A British industrial design student has used the woodpecker's natural shock absorbers as the inspiration for his new line of bike helmets.
Anirudha Surabhi, inspired by a minor bike accident that still left him with a cracked helmet and a concussion, decided to design the Kranium bike helmet for his senior project at the Royal College of Art. The key feature Surabhi wanted to copy from these resilient birds is the spongy bone that surrounds a woodpecker's brain. The region is made of trabeculae?small, beamlike bone structures that weave together into a sort of shock-absorbing scaffolding. Such structures are also present in smaller quantities within the beak, which keep it from pummeling the skull with the full force of hitting the tree.
In looking for a way to reproduce the spongy trabeculae of a woodpecker skull for the bike helmet's lining, he built prototypes from 150 different materials. He then smashed, crush, and pummeled the helmets prototypes in a homemade rig he built from an accelerometer and a plaster head, using an Arduino to record and interpret data.
The winner, to Surabhi's surprise, was cardboard. To use it in his bike helmet, he treats the material with a waterproofing agent to protect against rain and sweat and mimics the structure of woodpeck trabeculae by building a honeycomb structure. In an interview with the BBC, Surabhi said that the structure isn't exactly the same: Woodpecker cartilage has similar air pockets and spaces, but they're distributed in a way that's too complex for mass production. ?Hexagonal elements exist all over nature," he said, ?and they provide protection from impact in almost all directions" while still being easy to manufacture.
Like the cartilage, the air-pockets in the laser-cut ribs of cardboard collapse under force, which absorbs most of the impact of a crash. Lab tests show that the liner absorbs three times as much force as traditional polystyrene helmet liners. It's also as much as 15 lighter. Already available in the UK, it's expected to hit US shelves this summer.
Via BBC.
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