Ghatu Subhash, a professor at the University of Florida, studies collisions, impacts and crashes, both on the playing field and off, with the ultimate objective of designing a safer helmet.
Subhash and his collaborators may have achieved that objective by designing a helmet that protects against traumatic brain injury, which accounts for the two kinds of force athletes encounter during a football game.
“Currently, most football helmets are designed for linear force,” said Subhash, a UF Research Foundation Professor and the Knox T. Millsaps Professor of Mechanical and Aerospace Engineering. “Our design takes into account linear and rotational force.”
A linear hit is a centered, frontal hit that pushes the head straight back, according to a University of Florida press release. Helmets today, however, fail to account for rotational hits, which cause 40 percent of head injuries. The rotational hits occur because a helmet is round, and a frontal hit that misses the middle of the helmet can slide to the side, causing a shearing motion that jostles the brain inside the skull. Both forces can cause traumatic brain injury.
“This rotational force can be serious even when the impact is low,” Subhash said.
Each kind of force requires a different kind of protection, so Subhash and his colleagues designed a helmet with two kinds of protective chambers to cushion the skull.
One layer uses Newtonian fluids and the other uses a special fluid known as non-Newtonian. Newtonian fluids are water and air; non-Newtonian fluids are like gels. Layers of the two fluids form a protective padding, reducing the impact to the head, according to the release.
Together, the two layers absorb and distribute energy. As one layer experiences force and compresses, the fluid inside expands through a connecting tube into the next layer, neutralizing the force. When the pressure is removed, the chambers return to their original state, allowing for repeated use. One layer alone wouldn’t work, Subhash said. For instance, a foam or gel padding that experienced force would just transmit that force to the inside of a helmet, still impacting the skull.
“The fluid-filled cells within the helmet respond, so no matter the angle of impact, the helmet automatically protects any part of the head,” Subhash said.
The fluid-filled cushions work well in the laboratory, and the next stage will be testing on a wider scale with companies interested in manufacturing the helmets. Subhash and his colleagues will demonstrate the helmet for a group of venture capitalists in late January.
While the sports applications are obvious, they were not the inspiration for the research, Subhash said. For 15 years, he has been working to improve body armor and helmets for soldiers in combat, looking at materials that are resistant both to impact and velocity from bullets and other objects. UF neurosurgeon Ian Heger found out about his work, and the two began collaborating with UF radiology professor Keith Peters to develop a more protective sports helmet.
“It’s glamorous to talk about football, but that’s not the only application,” Subhash said. “Soldiers, skateboarders, bicyclists, firefighters, construction workers, and athletes in other sports can benefit from this design.”
The protective layers also are designed to be inexpensive and easy to use in retrofitting a helmet, making them ideal for parents who want to protect sports-minded children, according to the release.
“You could go to the store and buy strips of this material and a $10 helmet and make it safer,” Subhash said. “This works for kids, works for soldiers, and for professional athletes, too.”