Characterization of Soccer Ball Parameters for the Manufacturing of Protective Headbands and the Frequency Domain Evaluation of Football Helmets
thesisposted on 10.06.2019, 20:49 by Nicolas Leiva
An increase of 153,375 to 248,418 traumatic brain injuries (TBI) due to incidents in sports and recreation activities has been reported in the past couple of years in the US alone. These are grounds for concern for athletes partaking in sports with a high incidence of TBI’s such as football and soccer. The latter, traditionally not classified as a contact-sport, has attracted research due to participants using their head as an instrument for heading. Voluntary heading, in combination with lenient laws and regulations concerning TBI expose how soccer players are easily at risk of injury. On the other hand football, an aggressive sport by nature, has brought attention to the possible neurocognitive and neurophysiological ramifications of repetitive subconcussive impacts. One of these is in the form of a progressive neurodegenerative pathology known as chronic traumatic encephalopathy (CTE). A priori reasons revealed, led to a need to characterize the most important variables involved in ball-player interactions within soccer simulated gameplay. By understanding these, it would be possible to obtain parameters to design and manufacture new composite-material based protective headgear unlike products that are commercially available nowadays. In addition, development of a testing protocol focused on frequency domain variables - transmissibility and mechanical impedance - would allow to evaluate the performance of football helmets. A focus would be set on low impacts categorized as subconcussive impacts. Incoming velocity and inflation pressure were identified as the most influential variables affecting the peak impact force of a soccer ball. An innovative 6-layer carbon fiber headband, with silicone padding, was manufactured that out-performed existing headgear at attenuating peak linear acceleration. Lastly, quantification of the transmissibility and mechanical impedance indicated poor performance of football helmets below 60 Hz.