Testing a helmet containing accelerometers to compare force

A recent study by University of Cincinnati engineers found that football helmets made by four popular manufacturers are not designed as well as they could be. This is a concern, as concussions from football are a health concern across all age groups, from youth sports to professional leagues.

The study tested three helmets from each of nine models made by four companies. The researchers measured the mass of each helmet, an important consideration in determining how much force is applied during a hard tackle or impact with the ground. Each helmet was fit per manufacturer’s instructions onto a dummy similar to the kind used in automotive crash testing. The dummy contains accelerometers that measure how fast the head moves upon impact.

Using an instrument called a modal hammer that contains sophisticated sensors to measure applied force accurately, researchers delivered 20 blows by hand at seven impact points around the dummy’s bare head and its head while wearing each of the 27 helmets. By measuring force applied to the dummy with and without the helmets, researchers were able to single out the strengths of each helmet design at each impact point.

Helmets were able to mitigate between 52% and 83% of the translational acceleration — or change in velocity — researchers measured in the hammer strikes. However, the back of the helmets fared worst in testing, reducing less than half the rotational acceleration of hammer strikes. Several well-known NFL players, including Miami Dolphins quarterback Tua Tagovailoa, sustained concussions when the back of their head hit the turf.

The researchers suggest that field-based impact tracking in combination with lab tests could be more useful in future assessments. Once the force ranges are better characterized, the shell and padding can be designed to maximize energy absorption and reduce the majority of unrestricted or sudden head movements.