Body & Mind

Novel helmet liner 30 times better at stopping concussions

Novel helmet liner 30 times better at stopping concussions
A new, lightweight foam made from carbon nanotubes could be the future of protective helmets
A new, lightweight foam made from carbon nanotubes could be the future of protective helmets
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A new, lightweight foam made from carbon nanotubes could be the future of protective helmets
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A new, lightweight foam made from carbon nanotubes could be the future of protective helmets
Oblique impacts subject the brain to a combination of linear and rotational shear force
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Oblique impacts, associated with the majority of TBIs, subject the brain to a combination of linear and rotational shear forces

Researchers have developed a new, lightweight foam made from carbon nanotubes that, when used as a helmet liner, absorbed the kinetic energy caused by an impact almost 30 times better than liners currently used in US military helmets. The foam could prevent or significantly reduce the likelihood of concussion in military personnel and sportspeople.

Among sportspeople and military vets, traumatic brain injury (TBI) is one of the major causes of permanent disability and death. Injury statistics show that the majority of TBIs, of which concussion is a subtype, are associated with oblique impacts, which subject the brain to a combination of linear and rotational kinetic energy forces and cause shearing of the delicate brain tissue.

To improve their effectiveness, helmets worn by military personnel and sportspeople must employ a liner material that limits both. This is where researchers from the University of Wisconsin-Madison come in. Determined to prevent – or lessen the effect of – TBIs caused by knocks to the body and head, they’ve developed a new lightweight foam material for use as a helmet liner.

“This material shows great promise for enabling new helmets that are drastically better at preventing concussion,” said Ramathasan Thevamaran, the study’s corresponding author.

For the current study, Thevamaran built upon his previous research into vertically aligned carbon nanotube (VACNT) foams – carefully arranged layers of carbon cylinders one atom thick – and their exceptional shock-absorbing capabilities. Current helmets attempt to reduce rotational motion by allowing a sliding motion between the wearer’s head and the helmet during impact. However, the researchers say this movement doesn’t dissipate energy in shear and can jam when severely compressed following a blow. Instead, their novel foam doesn’t rely on sliding layers.

Oblique impacts subject the brain to a combination of linear and rotational shear force
Oblique impacts, associated with the majority of TBIs, subject the brain to a combination of linear and rotational shear forces

VACNT foam sidesteps this shortcoming via its unique deformation mechanism. Under compression, the VACNTs undergo collective sequentially progressive buckling, from increased compliance at low shear strain levels to a stiffening response at high strain levels. The formed compression buckles unfold completely, enabling the VACNT foam to accommodate large shear strains before returning to a near initial state when the load is removed.

The researchers found that at 25% precompression, the foam exhibited almost 30 times higher energy dissipation in shear – up to 50% shear strain – than polyurethane-based elastomeric foams of similar density.

“These characteristics make VACNT foams highly suitable as liner materials for modern protective helmets that aim to prevent TBIs by not only attenuating normal shock but also managing the rotational kinetic energy resulting from oblique impacts,” said the researchers.

The researchers had previously demonstrated the VACNT foam’s outstanding thermal conductivity and diffusivity, which would enable a helmet liner made out of the foam to remain cool in hot environments. Beyond its use in helmets, VACNT foam could be used in electronic packaging and systems to prevent shocks and keep electronics cool.

The study was published in the journal Experimental Mechanics.

Source: University of Wisconsin-Madison

7 comments
7 comments
Karmudjun
Amazing research findings. Too late to "impact" those already suffering from TBI, but we can see the future statistics when these helmets are in use. We should see better outcomes. But the consequences of even minor TBI or concussions can be long lasting, When helmets to block shrapnel were first used, instead of having dead soldiers, medics and front line hospital units found seriously wounded soldiers - death rate down, injury rate up. What will the outcome be with this new technology? I hope much better all around!
Nelson
The base fans for football are people that played football in high school. High school football is going the way of the dodo, so in a couple decades football will be on its way out.
Trylon
Sounds like MIPS will be shaking in their boots.
GaryM
Brain damage is what makes combat sports so....bad. I love watching boxing and ufc but what it does to the fighters is not right. A future where armored fighters get points
and wins based on punches to the armor that would identically cause an unarmored knockout is a real alternative and this foam is a path to that. Very exciting.
GaryM
To add to my other comment, having been tasered once in training this could be built into armor used and put a fighter down if he is hit with a blow to head armor that would identically cause a knockout to an unarmored opponent. Same excitement for the crowd but no brain damage for the fighters.
Don Miner Jr
Enough stacked carbon nano tubes to fill a helmet, seems like a pricey project, but you get what you pay for.
Kpar
A marvelous technology! I wonder how long before this gets to market? Carbon nanotubes ain't cheap!