NFL Helmet Testing Rigs Aren’t Accurate
Apparatus consisting of a crash test dummy‘s neck that better mimics reality. This could better simulate football head injuries. Image courtesy of L.A. Cicero / Stanford News Service.
A team of Stanford engineers suggests that current football helmet testing rigs do not properly simulate the real world movement that players experience during an impact. This represents a significant and potentially dangerous limitation as studies are suggesting that rotational movements, not tested by the rig, could be a leading cause of concussions.
Though modern helmets have almost eliminated skull fractures, concussions remained a significant medical, political, and even legal issue in the football community.
As a result, Bioengineering Professor David Camarillo and his team, have been collecting data to identify the movements that cause these injuries and replicate them in a rig to better assess the ability of protective gear to prevent concussions.
The Stanford team took MRI data and fed it into a computer model to determine which oscillations pose the most risk of injury. The results showed that the movement of the brain amplifies as it oscillates at 15-20 Hz.
The team then compared the findings to Stanford football players’ injuries. The acceleration data of these injuries were collected from accelerometers placed in the players’ mouth guards. The findings saw that the players would experience oscillations around 20 Hz regularly during injuries.
Camarillo explained that it’s really about the acceleration and the timing of the deceleration. Camarillo said, "It's possible that injury happens when the head whips back and accelerates the brain in one direction right as the brain is starting to go in the opposite direction."
"We know that if the head shakes at that frequency, the brain starts to rattle more violently," said Kaveh Laksari, a Stanford postdoctoral scholar. "So we have this mechanical system that exhibits a dangerous mode of motion, and then we find that the in-game impacts excite it at that frequency or something close to it. This introduces a fresh viewpoint on the possible cause of repetitive brain trauma. We need to keep that in mind when we're designing protective equipment."
How to Improve the Testing of Football Helmets
Current instruments test NCAA and NFL helmets in a setup similar to a guillotine. The helmet is attached to a dummy head and dropped from various heights to assess the effects of different magnitudes of impact. However, comparisons to this current setup and the data collected from the field did not correlate.
The traditional rig was unable to mimic the six-degrees-of-freedom movement seen in the field injuries. Namely, field tests show that high velocity rotations were not captured. Additionally, oscillations were in the 10-20Hz range in the field while the tests saw oscillations in the 100Hz range.
“The problem with having a model that doesn't re-create what players actually experience in the field, is that you could optimize a helmet to perform well in the drop test that unintentionally performs poorly in the field," said Fidel Hernandez, Stanford doctoral candidate and lead author.
"For instance,” Hernandez added, “you could design a helmet to stop linear head motion or high-frequency head vibration, because that shows up in the test, but that might not be what is most dangerous to your brain."
The redesigned rig created by Camarillo’s team consists of a dummy that better mimics the movement of a human neck. This dummy is then struck on the helmet. The hope is to better mimic the movements that cause concussions.
Even though Camarillo’s team have found an improved method to test football helmets, he notes that the system still isn’t perfect. The modified rig is only able to measure for a duration on 15-36 milliseconds which comes shy of the 50 milliseconds it can take the brain to start moving and face injury.
To improve the system further, the team is looking to create a rig that will slingshot a helmet into a stationary head to test accelerations and velocities with six degrees of freedom. Additionally, they are looking at methods to improve the traditional drop test method and the use of test dummies that better mimic the human neck.
"My opinion is that there should be some government regulation in standardizing helmet tests," declared Camarillo. "Hopefully people can use the methods we've described here to show that impact forces are being reproduced sufficiently or realistically compared to what's happening in the field."
Legal and Political Blowback?
Camarillo has a point. How has it been so long since someone thought to compare the helmet certification rigs with reality? After all, isn’t it a fundamental concept in engineering to ensure that your tests mimic reality?
However, this isn’t always the case in many industries. Often industries rely on standardization testing to ensure the “safety” of their products. Often these standards are created by members of the industry themselves. However, shouldn’t it be legally mandatory that the test be based on documented real life data instead of people in a board room looking for the cheapest, easiest option like dropping a helmet from 10 feet?
Besides, given the power of simulation to mimic reality this standardization shift should be a rather trivial change. In fact, a shift to simulation should actually improve the products, productivity, and development costs in the long run. Besides the technology for improved helmets are out there, just look at NASCAR.
Given the findings of this Stanford team and the legal battles going on in the NFL over concussions, it will not be surprising of for an email or memo at the league or helmet manufacturers to pop-up pointing at prior knowledge of the test’s shortcomings. If that is the case, the legal aftermath will not only become expensive. It will likely force the issue of the changes to this standard. It is a shame, however, that the system works reactively as opposed to proactively to ensure the safety of our NCAA, NFL, and young pickup football players.
What are your thoughts? Do you think laws should be created to ensure safety standards better mimic reality? Or should we stick with the current market system that assumes that consumer pressures will force the needed changes? If engineers and manufacturers didn’t verify if the certification tests match reality should they be liable? Is the current standards system a way for industry to hide behind a legal shield? Comment below?