Friday, February 1, 2008

Inspiring Materials

Both these materials seem to have great potential for bicycle helmet padding -allowing greater exploration of foam and in the case of Beta gel amazing shock absorption.

Also note worthy are more conventional materials. I found this great exploration of materials:, which illustrates that EPS (traditional helmet foam) has properties similar to more natural materials such as ultra low density cork and and low density balsa wood.

There is a tendency to select a low-density foam because it makes the helmet lighter. Figure 3 shows that alternative selections with the same plateau stress absorb much less energy: Polyurethane of density 0.53 Mg/m3, PU(0.53), for instance, absorbs only 0.4 MJ/m3. The value of figure 3 is the ease with which a first selection can be made, giving a short-list of viable candidates. Had the maximum permissible stress been 0.04 MPa, then the best choice among commercially available foams would be the low-density polyethylenes; had it been 10 MPa, then Al-Si metal foams or end-grain balsa would become the best choices, absorbing almost 10 MJ/m3.

I think these materials could also provide some great direction as well for a more natural, less techy helmet. I would like to say a more ecological helmet but I can't really validate that at the moment, and it seems a bit dodgy considering the current issues with cork. Perhaps though this could be an application for "tainted" cork that would be unusable to the wine industry.

and for a great story of invention check out this video of a new helmet liner developed by Australian physicist Don Morgan.

is also a great revolutionary technology and in my mind is superior to foam since it is rated for multiple impacts, thus producing a less disposable helmet. On their website ( they also mention a "Fit Seeker technology" that is pump free, however they dint elaborate on it.

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