Helmet + Ooobleck = ?

By Keenan Warhurst
Intermediate Category (Grades 9-10)
Experiment | Biology, Physics, Statistics

Concussions make up 93% of the sports and recreation related brain injuries in Canadian youth.  In the US, there are more than 4 million cases per year.  Since a young age, I have competed in sports and been interested in the prevention of concussion injuries related to sports. Intrigued by the fact that many sports helmets are firm, don’t fit well and still do not provide effective protection against concussions. In soccer there are currently no regulations for head protection despite heading the ball frequently during the game.

The purpose of this experiment is to compare the effects of Oobleck (a non newtonian fluid) as a soccer headband liner with both commercial headgear and current lack of headgear. Using accelerometer software measuring G force in X,Y, and Z axes, 100 drops were completed with head gear on a mannequin head. Resultant G force in all three axes were recorded. This was repeated for control (no headgear), commercial headgear and a uniquely designed oobleck lined soccer headgear. For oobleck designed headgear, oobleck pockets were inserted into a soccer headband with specification for consistency, components and thickness based upon previous experiments.  After 100 drops for each arm of the experiment, data was analyzed in each axis, comparing between headgear and correlated each axis with each other in order to explain if there were benefits or correlations between impact with each type of headgear.  Histograms were created for total G Force and a students’ T test for comparison between oobleck and control as well as oobleck and commercial headgear. As compared to control, the commercial helmet reduced G force in the following axes  61%X, 51%Y, and  75%Z.  Oobleck headgear as compared to control  reduced G force by 56% for X, 58% for Y, 87% for Z. Oobleck headgear was 81% better than control on the main axis (z) and  33% than the  commercial helmet on the Z axis.  There is little correlation between increased movement in one axis than others between control, headgear and oobleck except small correlation , R>0.3 for headgear.

In commercial headgear,  as X and Y increase, Z gets smaller with commercial headgear.  There is more lateral and forward head movement with commercial headgear due to “bounce” one impact of styrofoam headgear. This “bounce” does not happen with oobleck, its effect reduces movement in all directions as it slowly absorbs the impact of the hit. This results in less forward and lateral head movement as well as overall reduction in Z or vertical axis G force. On scatter plot data, there is a positive correlation with a positive slope for oobleck likely because of the location of the drop. When the drop makes the head move around more, there is overall more Z movement. This is in the context of overall reduced G force for the impacts.  Oobleck  statistically reduced total G force as compared to helmet and control with p=0.05.  Slow motion video demonstrated both wave motion and research supports that internal molecular use of kinetic energy may explain oobleck ability to absorb force in all directions. More research is needed to understand the behavior of oobleck with different applications of force – soft, fast, multidirectional and in different environments.  Additionally more research is needed to understand the fatiguability of oobleck over time and repeated impact.

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