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Engineers Design Safer Football Helmets

Engineers Design Safer Football Helmets
Image Courtesy of Technology Review

Rishika Kenkre
Staff Writer

Helmets have generally failed their main function, which is to protect the player’s head from brain injury. That was until University of Michigan’s professor Ellen Arruda revealed a prototype of helmet advancement that disperses the kinetic energy that moves through the head after an impact.

“What we have done is take a look at what it is about an impact that can cause brain motion and, therefore, damage to the brain,” said Arruda in an interview with The Bottom Line. “When there is an impact, like a helmet to helmet impact, there is a pressure wave or a stress wave that goes through the helmet and through the skull, and that can accelerate to the brain.”

Although football helmets are supposed to protect the players, they do not have much of an effect in preventing hits to the side of the head that can cause traumatic brain injuries. According to a new study, impacts that cause rotational force are not prevented by the sports equipment. Experts and athletes have become increasingly worried about consistent head traumas causing chronic traumatic encephalopathy (CTE), a degenerative disease with effects similar to Alzheimer’s. These symptoms include memory loss, mood swings, motor skill problems, paranoia and memory problems.

“I think they’re doing great work at the University of Michigan,” UCSB engineering professor Glenn Bletz said. “Traumatic brain injury is a major health problem. A colleague of mine who studies the mechanics of brain injury (separate from the University of Michigan effort related to helmets) tells me there are over 300,000 concussions per year in the U.S. from sports alone. You can imagine football is probably one of the significant contributors here. On a personal note, my son is cut out to be a football player but, as parents, my wife and I are hesitant to let him go down that path due to the prevalence of brain injuries in that sport.”
Athletes in football, hockey and other contact sports are at risk of having this disease. Generally, the way to prevent this from happening is to avoid playing the sport, waiting for a while to play the sport or wearing sports equipment. Still, wearing sports equipment previously was not found to be quite effective.

“There’s also the impulse of the impact, which you can think of the pressure times the time or the duration of the impact,” said Arruda. “That impulse also travels through the helmet to the skull and to the brain, and cause the brain to move relative to the skull. There are these two components to the impact for the pressure and impulse. We looked at current helmets and found that they do a good job limiting the magnitude of the force that gets through; however, they don’t do a whole lot to limit the amount of impulse to get through. Our technology is designed to do both. Therefore, we are limiting all of the harmful effects of the impact not just one of them”

In a study done before these helmets were developed, researchers tested normal football helmets with a method called the the standard drop test, used in the National Operating Committee on Standards for Athletic Equipment. A crash test dummy wore the helmets and scientists put sensors on the dummy’s head so the researchers could see the rotational and linear impact. Linear impacts cause brain bruising and skull fracture, while rotational impacts cause concussions. The researchers found that the helmets reduced the risk of skull fracture by 60 to 70 percent and lowered the chance of brain tissue bruising by 70 to 80 percent. Unfortunately, the helmets only reduced the risk of traumatic brain injury by 20 percent when compared to not wearing a helmet. Therefore, collisions can be very damaging to athletes that get impacted constantly.

Through close and careful examination, sports equipment can be better formed to actually protect the brain. The prototype that they have created is composed of three cheap polymers, including a viscoelastic polymer. Each of the polymers contribute together to absorb the pressure wave that moves through the head after an impact.
Through the use of two-dimensional mock cross sections of materials, they enabled the football helmet to perform its true function. They experiment with a table-top collision simulator to test the present helmet model compared to the one they created. They differentiated how much energy traveled through their type and the normal helmet. Through the use of high-speed camera, they had the ability to observe how the brain model reacted to the impacts in both systems. The impulse was reduced all the way to 20 percent of what traveled to the brain model in the conventional helmet. This lowered the impulse by a huge magnitude.

“Anyway, the design being carried out at Michigan is quite clever,” Beltz said. “They use multiple layers of different materials that, together, dissipate the energy associated with an impact. It is this energy that seems to correlate with brain injuries. I’m proud to point out that one of the researchers at the University of Michigan who works on this, Professor Michael Thouless, worked at UCSB as a postdoctoral researcher early in his career in the group of the late Professor Tony Evans. It appears the University of Michigan is working to bring the new helmet technology to market, so hopefully football players will benefit from this research in the very near future.”

Since the team produced a foundation that depends on the characteristics of the first two levels to “tune” the wave, when it hits the viscoelastic layer, its frequency is within the spectrum that the material can absorb. This same idea can be applied to military helmets for soldiers.

“There has been a lot of interest, and I have been contacted by a lot of entities for more information and asking questions about it,” said Arruda. “I think it has been quite positive. We entered this competition called the Head Health Challenge and this is sponsored by the NFL, GE, NIST and Under Armour. We submitted this prototype, a sort of 2D plate-like prototype of our design. They picked five finalists and we are one of the five finalists. We get a year and some funding to try to optimize our design. In our case, we put a combination of materials together that works fairly, but we haven’t optimized that combination yet. Part of the optimization is getting the mass where we want it to be, so we are spending the year working on those types of things. Then we’ll submit another prototype and they will test them at NIST and we’ll see who the overall winner is.”

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