Characterization and evaluation of head impact sensors and varsity football helmets

Cummiskey, Brian R. MSME, Purdue University, May 2015. Characterization and Evaluation of Head Impact Sensors and Varsity Football Helmets. Major Professor: Eric A. Nauman, School of Mechanical Engineering. An increased understanding of the effects of brain injury in recent years has led to greater attention being given to the topic. A desire to investigate the causal agents of these injuries in athletes has led to the development and use of several devices that track head impacts as well as improving helmet technology to protect players from said impacts. In order to determine which devices are able to best measure head impacts, a Hybrid III headform was used to quantify the accuracy for translational and angular accelerations. Testing was performed by means of administering impacts to a helmet on the headform, with each device mounted according to manufacturer instruction, using an impulse hammer. For peak translational acceleration, the worst locational root-mean-square error for a head mounted device was 74.68% while the worst for a helmet mounted device was 297.62%. Head mounted devices outperformed those mounted in helmets and should be the basis of future sensor designs. For the sake of determining the effectiveness of recent helmet innovations, several helmet models were fastened to the headform in order to measure the response accelerations from impacts. The impulse hammer provided transient force data which allowed for the comparison of the input blow and output accelerations for each impact, and several metrics were defined and evaluated to determine helmet impact mitigation ability. Relative helmet effectiveness between models varied by region. The lowest peak translational acceleration metric was 0.31, and the highest was 0.57. The corresponding angular acceleration metric had a low of 0.23 and a high above one at 1.71. The helmets evaluated were more consistent in mitigating peak translational acceleration than peak angular acceleration.