For almost as long as American football has existed, it’s been assumed that helmets would protect players from a direct blow to the head. It now appears, however, that protection against a direct blow may not be enough.
Using sensors and a specialized test stand, engineers are discovering that the root causes of head trauma may lie in a complex pattern of forces that today’s helmets aren’t equipped to handle. The solution -- as indicated by studies performed on the new apparatus -- may lie in a helmet designed to protect against the effects of both linear and rotational forces.
“The results of our studies are pretty alarming, in terms of how little protection football helmets provide against concussions and traumatic brain injury,” John Lloyd, research director of Brains Inc., told more than 2,000 engineers during a keynote speech this week at NIWeek 2014 in Austin, Texas.
Brains Inc. studied the performance of 21 different professional football helmets, using automotive crash dummy heads equipped with sensors. The sensors measured linear and angular accelerations, as well as impact forces. By using the sensors to examine forces beyond the obvious first impact, the company has been successful in dissecting the step-by-step chronology of events that lead to brain injuries. Its studies have shown that nearly all blows to the head are accompanied by rotational forces that up to now have been largely unaccounted for, Lloyd told Design News. “It’s like dropping a pen. Once it impacts the ground, it will bounce up and then rotate. We need to be able to mitigate both of those forces if we want to reduce the risk of head and brain injuries.”
The key to the company’s findings lies in the test stand’s ability to collect data on events that occur just milliseconds apart. To do that, it used National Instruments’ CompactDAQ controller to gather data from linear accelerometers and angular rate sensors and then measure the lag time between peak forces. Lloyd said an understanding of the lag time was critical because it enabled the company to design a helmet that’s optimized for both sets of forces.
The new helmet design, currently in search of a manufacturer, employs a matrix of “non-Newtonian” materials in the inner liner to provide cushioning for both linear and rotational forces. The materials work by changing their behavior in response to the rate of applied force. A faster rate causes them to behave like a solid. At a slower rate, they act like a liquid. By behaving in that way, the materials can respond not only to the magnitude of the forces, but also to the rate at which they are applied. Lloyd, who has a patent pending on the technology, believes the new helmet could dramatically reduce the number of concussions in sports.
Ultimately, the new design could also serve in other applications, including motorcycle and bicycle helmets. For now, however, its primary target will probably be football. “Compared to a standard football helmet, we believe this design could reduce brain injury by 50%,” says Lloyd.
In the following video, applications engineer Jeff Munn of National Instruments shows how a test apparatus using CompactDAQ controller gathers data from sensors in a crash dummy head: