With ongoing research about the relationships between football and concussion, head injuries and long-term brain disease, researchers at the University of Michigan in Ann Arbor are developing a shock-absorbing football helmet that can effectively dissipate the energy from a hit to the head.
“We now understand that sports helmets need to protect both the skull and the brain from the harmful effects of an impact,” says Ellen Arruda, professor of mechanical engineering and biomedical engineering at U-M. “Skull fracture is prevented by minimizing the amplitude of the force transmitted through the helmet, and to a certain extent, this also helps protect the brain from injury. In order to better protect the brain, the energy carried by the impact needs to be dissipated.”
Arruda notes that there are several strategies for dissipating energy. One strategy is fracture, which includes cracking and breaking. The creation of cracked surfaces dissipates energy, but this process can’t be used repeatedly. It is a useful strategy for a bicycle helmet; if it cracks and breaks as a result of an impact, it is replaced.
“The strategy we have developed is intended to be used to dissipate energy in impact after impact after impact, Arruda says. “Not only can it better protect the brain in football impacts, it can be an effective strategy in bicycle accidents even if the helmet doesn’t crack and break.”
The helmet system, known as Mitigatium, is made of three materials. The first layer is much like the hard polycarbonate that present-day helmets are made of, and the second layer is another type of plastic. Together, these two layers reflect most of the initial shock wave from a collision. The third layer, known as the “visco-elastic” layer, then dissipates the remaining shock via vibrations.
Sponsors of the Mitigatium system include General Electric, the National Football League, National Institute of Standards and Technology and national sports clothing company Under Armour.