Doug Browne Jeff Markle Tyler Severance

1. Doug Browne Jeff Markle Tyler Severance Football Helmet to Reduce the Risk of Subdural Brain Hemorrhaging and Concussions by Reducing Rotational Acceleration

2. What Causes Subdural Hemorrhage? • Subdural hemorrhaging occurs when the blood vessels that connect the dura to the brain rupture • This can happen when the brain moves relative to the dura, causing the connecting vessels to stretch and burst • Due to a higher density of CSF relative to brain tissue density • The maximum strain was found in research and verified in Vanderbilt cadaver lab during advisor guided dissection

3. Rotational Acceleration • From cadaveric studies, the connecting blood vessels undergo permanent deformation at 20% strain and total rupture at 150% strain which occurs at accelerations between 4,500 and 10,000 rad/s2

4. Rotational Acceleration Dangers in Football • Already proven that collisions in football often exceed dangerous levels of rotational acceleration • In all levels of football (high school, college and professional) top 1% of collisions reach critical levels of rotational acceleration • Collisions cannot be prevented without drastic change in the sport; however, helmet design can be modified

5. NOCSAE • The National Operating Committee on Standards for Athletic Equipment is the governing body that regulates standards for football helmets. • Helmets are only required to prevent against levels of translational acceleration that would cause skull fractures.

6. Southern Impact Research Center • Tests helmets for NOCSAE and does a lot of independent research on helmets. • Met with Technical Director David Halsted who shed light on many problems with designing a new, improved helmet

7. SIRC Drop Test Setup

8. SIRC Projectile System

9. Helmet Design Problems (remove slide?) • Helmet it not well coupled to the head during a collision • Athletes can suffer brain injury even when head is not involved in the collision • Current helmets are effective at dampening blows to the head (difficult to improve upon), but this is a different issue than lowering overall angular acceleration

10. Design Problems to Overcome • After meeting with Dave Halsted, it became apparent that this problem is more complex than was initially predicted • He mathematically proved that changing cushion design would have minimal, if any, impact on helmet function

11. What we’ve done so far • After meeting with Mr. Halsted, it became apparent that this problem is more complex than we initially imagined. • Together, we identified three main issues our team could “tackle” • Helmet weight • Relatively large range of motion • Detection of potential brain injury

12. New Helmet Design • Lightweight helmet that keeps the same levels of protection against linear acceleration as current models • Include in the helmet a device that indicates when dangerous levels of rotational acceleration have been reached. • Attempt to create a seat belt based design to prevent the head from reaching the peak levels during the collision

13. Thinking outside the box • The seat belt theory has potential, but a helmet alone won’t regulate the motion • Shoulder pads can be included to transform the system from just a head to the entire upper torso • Perhaps it will be possible to tether the helmet to the pads + + ? =

14. Other Possibilities • Another issue that can be addressed is that a significant number of subdural hemorrhages are undetected (sources vary widely ) • Possible to create a safety feature that would indicate when dangerous levels of acceleration have been reached • Apply accelerometers to the back of the helmet which could signal that a player should be removed from play and examined by a professional

15. What we’re doing now • We are currently developing a prototype helmet that will be able to be tested using the equipment at the SIRC • Taking/modifying elements from different current helmets so we don’t have to manufacture many new parts • Attempting to procure a set of shoulder pads to use in our design • Via local high schools • Searching for suitable accelerometers to use as a potential indicator • Continuing to run ideas by Mr. Halstead to assess our progress • Planning a future trip to Knoxville for more testing

16. Steps to come • If all goes as planned, we will have a working prototype that can be tested by the end of March • Further testing and modification can occur as needed for the rest of the semester

17. References • Huang HM, Lee MC, Chiu WT, Chen CT, Lee SY: Three-dimensional finite element analysis for subdural hematoma. J Trauma 47: 538–544, 1999. • Depreitere B, Van Lierde C, Vander Sloten J, Van Audekercke R, Van Der Perre G, Plets C et al.: Mechanics of acute subdural hematomas resulting from BV rupture. Journal of Neurosurgery 104(6): 950-956, 2006. • LöwenhielmP: Strain tolerance of the vv. cerebri sup. (BVs) calculated from head-on collision tests with cadavers. Z Rechtsmedizin75:131–144, 1974. • GennarelliTA, Thibault LE: Biomechanics of acute subdural hematoma. J Trauma 22:680–686, 1982. • Lee MC, Ueno K, Melvin JW: Finite element analysis of traumatic subdural hematoma, in Proceedings of the 31st Stapp Car Crash Conference. New York, NY, Society of Automotive Engineers, 1987, pp 67-77.

18. References Con’t • Lee MC, Haut RC: Insensitivity of tensile failure properties of human BVs to strain rate: implication in biomechanics of subdural hematoma.J Biomech 22(6-7): 537-42, 1989. • Forbes JA, Withrow TJ: Biomechanics of Subdural Hemorrhage in American Football. Vanderbilt University, 2010

19. Final Note: • To learn more about Southern Impact Research Center, please visit: • http://www.youtube.com/watch?v=hwA-hiFu4Xw • http://www.soimpact.com/