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Improved helmet design

A new football helmet design aims to blunt some dangerous physics that today’s models ignore.| Short Read

About this video

A new football helmet design aims to blunt some dangerous physics that today’s models ignore. Current helmets are made to reduce the peak force of an impact and prevent skull fractures. They do that well. But they don’t actually dissipate the energy of a collision. They leave that to the brain. The new Michigan Engineering system, which is partially funded by the NFL, could lead to a safer helmet.

The system is made of three layers. The first two convert the frequency of the incoming pressure wave from the hit into another frequency that the third layer can grab hold of and dissipate through vibration.

“You can dissipate energy by fracture and plastic deformation and that’s sort of the idea with a bike helmet,” said Ellen Arruda, a professor of mechanical engineering and one of the leaders of the project. “If you’re wearing it and you fall and you hit your head and the helmet cracks, you dissipate energy and it protects your skull and protects your brain. You throw it away and you get a new helmet. That’s not a practical solution in a football game. We designed our helmet to optimally dissipate the energy of an impact, every time it’s hit. Not just once, but every time.”

About the Professor

Ellen Arruda is a professor of Mechanical Engineering and Macromolecular Science and Engineering at Michigan Engineering. She studies the mechanical behavior of materials including polymers, elastomers and soft tissue; tissue engineering of tendon and muscle constructs; constitutive modeling of growth, remodeling and functional adaptation in soft tissue; deformation mechanisms in polymers; crystal transformation mechanisms in semi-crystalline polymers; split Hopkinson pressure bar testing of polymers and elastomers for high strain rate applications including crashworthiness in automotive applications.

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The electrons absorb laser light and set up “momentum combs” (the hills) spanning the energy valleys within the material (the red line). When the electrons have an energy allowed by the quantum mechanical structure of the material—and also touch the edge of the valley—they emit light. This is why some teeth of the combs are bright and some are dark. By measuring the emitted light and precisely locating its source, the research mapped out the energy valleys in a 2D crystal of tungsten diselenide. Credit: Markus Borsch, Quantum Science Theory Lab, University of Michigan.

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