Effects of Helmet Surface Geometry on Head Acceleration in High Velocity Water Sports

This paper explores the effects of helmet surface geometry on head acceleration in high-velocity water sports in an effort to help reduce the probability of concussion. An instrumented Hybrid III anthropomorphic head was fitted with a football helmet covered in a smooth control shell and with one covered in a shell with a designed geometry involving dimples and fin/channels. The head was dropped from a height of 73 inches (185.42 cm) into a tank of water at varying impact angles and the peak accelerations were recorded and compared at each impact angle. High speed camera images were also taken to observe dynamic behavior of the water during the impact. The results showed an average reduction in acceleration over all angles of around 17% and a peak reduction in acceleration of 37% for impacts on the crown of the head. High speed camera analysis and acceleration analysis also revealed that fins were the dominant factor in acceleration reduction, but dimples did have a moderate effect. It was also determined that the reduction in acceleration created by the geometry could result in around a 30% reduction in the probability of concussion at the optimal impact angle. Overall, these results showed that helmet geometry can significantly reduce the linear acceleration a head undergoes in high velocity water sports. Further investigation is needed to see how geometry influences rotational acceleration and how to implement this geometry into a helmet design.