Building a better motorcycle crash helmet

Methinks the good Doctor is on to something. If the intent of a helmet is to absorb shock and decrease the chance of snapping ones neck and/or tweaking the brain inside the skull (torsional force and close head injuries), it makes perfect sense to build some movement into the outer shell, or make the outer shell out of a softish energy asboring material that is also pucture resistent. He is not the first one to try this. Years ago I met a guy named Uwe (pronounced you-ee) from Germany who had a helmet that kinda looked like a golf ball but had a relatively soft outer shell (that would emulate a hard shell being able to move somewhat). In his opinion, it saved his life when he went under a guard rail in a high speed crash. Instead of the helmet stopping him from going under it, part of the outer shell sheered off (if hard and moveable, it would presumably move out of the way)! It was still able to absorb the shock of whatever eventually stopped him. However, what ever the Doc comes up with will probably never be sold here because of antiquated DOT requirements and our lovely product liablilty laws or lack of common sense there of!

Looks like a boondoggle to me. I wouldn't trust my brain to someone's science experiment..



My guess as an ex physics grad student and who got his doctorate in mechanical engineering is this...to reduce the torsional forces you want the least amount of friction between the helmet and the ground...think of something that has low friction...an ice skate, skis, snowboard...has a smooth surface like a conventional helmet.



Now the graphic he has shows some sort of covering ripping off...it could be with this helmet that there is a large spike in the torsional force at

a) the moment the covering starts to rip off,

b) when the covering has mostly been peeled off and its getting pulled of the helmet entirely when it snags on something on the pavement

c) after the covering is gone and I have the not as smooth underlying part of the helmet that was glued on to the covering which is now rubbing along the asphalt.



As far as the fancy graphic is concerned if you read the script above it is says:

"The next stage was finite element analysis, utilising a model produced by Strasbourg University. The concepts tested showed that with zero friction and ideal materials there were theoretical improvements of up to 85% in protection against rotation and up to 40% against linear forces"



Translation: "This data is from a computer model not from an actual test with an actual helmet with actual moving asphalt



I actually did some finite element analysis in college...there are all sorts of ways to get it wrong, or to leave out of the modeling important nonlinear effects that invalidates your results.



the 6,900 lives part is amost certainly a bogus number using all sorts of assumptions.





suggest investing in a MSF course until a reputable government agency has tested this in a well thought out controlled experiment. Government agencies are slow, but there is no replacement for good science.

Now the graphic he has shows some sort of covering ripping off...it could be with this helmet that there is a large spike in the torsional force at

a) the moment the covering starts to rip off,

b) when the covering has mostly been peeled off and its getting pulled of the helmet entirely when it snags on something on the pavement

c) after the covering is gone and I have the not as smooth underlying part of the helmet that was glued on to the covering which is now rubbing along the asphalt.

Click to expand...

So, the pliable covering would ostensibly be in quasi-static contact with the ground, and the covering would then have it's low-friction surface with the helmet shell. It doesn't say how it's constructed, but imagine Kevlar fabric on a shell with perhaps a dry lubricant between. If the covering were torn away, then subsequent friction probably wouldn't be any worse than from a conventional helmet. Besides, if the helmet lining did "snag" - on a railroad spike, or whatever - then the danger to the downed rider is probably much greater from the snagging object itself.

As far as the fancy graphic is concerned if you read the script above it is says:

"The next stage was finite element analysis, utilising a model produced by Strasbourg University. The concepts tested showed that with zero friction and ideal materials there were theoretical improvements of up to 85% in protection against rotation and up to 40% against linear forces"

Translation: "This data is from a computer model not from an actual test with an actual helmet with actual moving asphalt

I actually did some finite element analysis in college...there are all sorts of ways to get it wrong, or to leave out of the modeling important nonlinear effects that invalidates your results.

Click to expand...

The chart is from a real mechanical test - of something, a helmet, I guess, from an independent lab. The spikes in tangential load do seem to be dulled with the new helmet. I'm not a bioengineer, so I don't know if it's the total impulse or the peak forces that are important. I too, have the feeling (doctorate Mat Sci, spec in mechanical behavior) that FEM can be worse than useless for systems this complex, even when performed absolutely properly. I imagine Philips might feel the same way too, but FEM "validation" is something that managers/funders seem to like, for reasons that I don't understand.

Of course, testing is needed to validate claims of improved safety, but certification for street use may not be too hard, if (in a crude sense) this technology is mostly a clever way of covering a conventional helmet in leather.

the 6,900 lives part is amost certainly a bogus number using all sorts of assumptions.

Click to expand...

Yep. In fact, it says "Projecting this improvement [60% reduction in torsional force] on to the current motorcycle injuries, if all riders were to wear a Phillips Helmet the potential savings could be..." A completely made-up estimate, but he's gotta have some estimate.