Shockwave absorption by fractal microcubes.

No really, 3D printed fractal microcubes.

Tiny, 3-D printed cubes of plastic, with intricate fractal voids built into them, have proven to be effective at dissipating shockwaves, potentially leading to new types of lightweight armor and structural materials effective against explosions and impacts.

"The goal of the work is to manipulate the wave interactions resulting from a shockwave," said Dana Dattelbaum, a scientist at Los Alamos National Laboratory and lead author on a paper to appear in the journal AIP Advances. "The guiding principles for how to do so have not been well defined, certainly less so compared to mechanical deformation of additively manufactured materials. We're defining those principles, due to advanced, mesoscale manufacturing and design."

Shockwave dispersing materials that take advantage of voids have been developed in the past, but they typically involved random distributions discovered through trial and error. Others have used layers to reverberate shock and release waves. Precisely controlling the location of holes in a material allows the researchers to design, model and test structures that perform as designed, in a reproducible way.

One of the biggest problems in body armor and particularly helmets for both sports and soldiers is dissipating impacts. Older helmets concentrated on the hard unbreakable shell, which withstood impacts well but mostly transmitted the impact energy to a different part of the body, like the neck. So you don't die of a skull fracture, you die of a spinal fracture instead. Or a brain injury, that happens too.

This is an interesting approach where they're using the shape and location of the holes in the material to maximize the dissipation of shockwaves. Very cool. If they make it work, sporting protection like football helmets could improve a great deal.