[i] Since then, the 2012 study from the same group notes that the three lowest rated helmets from the previous study are now “off the market”.[ii] This is a clear sign that engineers and scientists are taking note of these studies and working together to develop better and safer equipment. One issue with many football helmets, including the five star rated ones, is that while they do a great job preventing skull fractures, they may not do so well where concussions are concerned. While they they have the ability to absorb linear hits very well, angular impacts, which jerk the head and often cause more concussions than blunt force, don’t always fair as well.
In motorcycle stlye helmets, a different type of stress analysis can be seen. Many are poorly designed in that they only look at one factor of injury prevention; they are very well designed to reduce head form deceleration, but this alone does not make it optimized for injury prevention. When an average helmet was tested with a frontal impact, the brain pressure varied from 94 kPa to 350 kPa, which is high above the threshold. For a visible injury, the maximum stress that a brain can handle is 180 kPa in tension and 234 kPa in compression. It has been recently found that the elastic limit within the foam used, has the highest influence on head injuries. One way to measure the stiffness of an elastic material is known as Young’s modulus. To combat injury prevention successfully, other factors such as the thickness of the shell, the Young’s modulus of the foam and the Young’s modulus of the shell must also be taken into account. Each of these factors will increase the injury prevention of any helmet to a varying extent. [iii]
The Future of Helmet Engineering
New developments in helmet technology are coming onto the market and looks to address the problem of rotational acceleration. While no helmet on the market can completely eliminate this force, Peter Halldin, a biomechanical engineer at the Royal Institute of Technology is coming very close. He recently designed a system known as the Multidirectional Impact Protection System (MIPS). Instead of being a stationary helmet, a plastic layer sits snugly on the player’s head beneath the padding and is able to keep the head “floating”. In a circular acceleration test, the MIPS helmet performed about 55% better than that of a standard helmet.[iv] While it doesn’t appear to reach that magnitude of performance in every direction it is very plausible that a high reduction in concussions would be seen. While this technology is used sparingly already in snowboarding and cycling helmets, it is just beginning to be seen in hockey and football.
While some will argue that it is the athlete that makes the biggest impact on the future of sports, it can be said that the mechanical engineers behind the development of the equipment play a bigger role. Without these advances, the time on the field for these players would be greatly reduced.
[i] Virginia Tech Study “Football helmet ratings for reducing concussion risk.” ScienceDaily, 11May 2011
[ii] Virginia Tech (Virginia Polytechnic Institute and State University) 2012 May 1
[iii] Deck, C, Baumgartner B., Willinger R., 2003 “Helmet Optimization Based on Head-Helmet Modeling” .
[iv] Foster, Tom “The helmet that can save football”. Popular Science 18 December 2012