For four students who took aerospace professor Massimo Ruzzene’s graduate course in experimental structural dynamics last fall, the Super Bowl was a whole new ball game.

Instead of rooting for the Broncos or the Seahawks, they were rooting for the helmets that get banged, bounced and beaten during the course of the game.

They can blame this game-changer on a class project, “Dynamic Characterization of a Football Helmet” which they initially completed for Ruzzene in December but are now preparing to present before the Society for Experimental Mechanics this June.

“Usually, when I teach this class, we use a laser vibrometer to measure the motion on a flat surface or a beam. But that’s very easy, and not like anything they would have to solve on their own. I wanted something that would test their problem-solving abilities,” said Ruzzene.

“So I took a football helmet, a curved surface, and told them to find a way to measure its vibration response. They had to come up with the methodology and test it. Their results are good, something that can be used to help others redesign helmets, for football and maybe other uses.”

A redesigned helmet, he pointed out, could lead to a lower incidence of mild traumatic brain injury and concussions, two hazards widely associated with football.

While many studies of this phenomenon focus on measuring the acceleration of the head inside the helmet, Ruzzene’s team – composed of AE and ME graduate students - focused entirely on the dynamic behavior of the helmet itself.

“Knowledge of the vibratory motion of the helmet may lead to an improved understanding of what causes the most severe injuries to the brain,” Ruzzene added.

By splitting the helmet into several experimental “zones,” they were able to resolve the issues created by its curved surface. To generate the vibrations, they glued a piezoelectric transducer (PZT) to the inner surface of the helmet. A bi-dimensional Scanning Laser Doppler Vibrometer (SLDV) measured the resulting wave.

The results, illustrated vividly by a color-coded 3D scan, suggest that a more strategic placement of the air venting “holes” in the helmet may act to disburse or contain the propagation of impact vibrations. Vibrations migrate between the holes, he said, but not beyond them.

But Ruzzene stops short of issuing a concrete prescription for new helmet designs.

“The fact that these students have found a way to capture the images of vibration propagation is impressive. It sets up a way for someone to make a better helmet,” he said. “For me, as a professor at Georgia Tech, it is proof, once again, that if you set our students loose on a problem, they will come back with a solid, scientific answer. They are an impressive bunch.”

Working together with Dr. Ruzzene to generate and write up this research were AE graduate students Matteo Carrara, and Amy N. Williams and ME graduate students Aaron Darnton and Marshall Schaeffer.