(E-168) Influence of Football Facemask Testing Angle on Quasi-Static Stiffness Performance

Introduction:: Approximately 1.6 to 3.8 million concussions occur in the United States due to sports [1]. With American football having such a high risk of head injury, safety standards are in place to ensure the helmet system, including the facemask and the helmet shell, are durable and dissipate energy. However, helmet manufacturers have significant design freedom within these standards, resulting in large variations, specifically in the facemask. Furthermore, these design variations could influence the performance of the helmet system by adversely effecting facemask stiffness or energy absorption. Facemask designs vary generally by how they attach to each helmet type, creating diversity in the angle at which the facemask will attach. According to the Clemson Headgear Impact Performance (CHIP) Lab’s patented method, quasi-static stiffness testing of facemasks requires the facemask be isolated from the helmet and compressed at locations equivalent to on-field impacts [1]. However, there was no method to determine the angle of attachment and angle of compression in the patent, thus assuming that each helmet style should be evaluated at the same angle even with the differences. This study explores a novel method to standardize the determination of the testing angle of football facemasks for current and future helmet types to ensure proper quasi-static measurements of facemasks.


Materials and Methods:: A total of 6 current helmet types were used to create this method: Riddell Speed, Riddell SpeedFlex, Vicis Zero 1, Vicis Zero 2, Schutt Q11, and Schutt F7. The helmets were equipped with a facemask and placed on an upright Hybrid III head of a linear impactor system at an altered “A” position from Biocore, with the alpha angle moved to zero degrees [2]. A DSLR camera was then used with a bubble level tripod to capture an image of the helmet from the anatomically left side profile. The general position of the bubble level tripod was marked in the lab after the first image to assist with repeatability. Each helmet had a minimum of 10 images taken, each with a different facemask. Types of facemasks were pulled from a variety of positions, with a maximum of 2 images per position group in the total of the 10 images. These images were then imported into photo editing software. A baseline was drawn at the base of the fixture, as a verification of the horizontal 0 degrees. This was then copied and rotated 90 degrees and placed tangent to the attachment bar of the facemask. This was copied and rotated to be in line with the middle of the attachment bar. An account of the initial 7-degree forward-tilt of the head will help to deduce the attachment angle of the single mask. This process was repeated for the 10 images and an average was taken for the final attachment angle.

Results, Conclusions, and Discussions:: All results are summarized in Figure 2. Of the six helmet types that were tested, all but one had attachment angles forward-tilted relative to the vertical. Both Riddell helmets had average attachment angles of 16 degrees forward-tilt, with the Speed varying from 13 to 18 degrees and the SpeedFlex ranging from 14 to 20 degrees. The Q11 and Zero 2 helmet styles both had averages of 28 degrees forward-tilt, with the Q11 ranging from 25 to 32 degrees and the Zero 2 ranging from 23 to 32 degrees. The F7 helmet was the most consistent with an average attachment angle of 32 degrees forward-tilt with a range of just 30 to 34 degrees. The most unique helmet was the Zero 1, with an average attachment angle of 44 degrees backwards-tilt relative to the vertical.

These results show that helmets do indeed vary in the system in which the facemask attaches. This indicates that each helmet style should be treated independently when evaluating the components, like the facemask. These results prove that there is a repeatable method that provides a standard for facemask performance testing. Future studies should investigate the optimal angle attachment for facemask performance and energy absorption, helping to inform helmet manufacturers and improve player safety. This method is one way to evaluate the differences in helmet systems, however, this method may need to be modified as new attachment technology emerges, as seen in the Riddell Axiom helmet. Overall, this method will aid the future of helmet safety research, protecting the players at the highest level.


Acknowledgements (Optional): : Thank you to the Clemson Bioengineering Department and the Clemson Food, Nutrition, and Packaging Science Department for support of this research.

References (Optional): : [1] Bina et. al. Proc. Inst. Mech. Eng. J. Sports Eng. Tech. 2019 June. Vol. 233(2) [2] Biocore. Biocore Biomechanics, Consult. and Research. 2019.