Materials

Fractal void cubes could make for better shock-dissipating armor

Fractal void cubes could make ...
Simulated images show how the cubes with more intricate fractal void patterns dissipate shock waves more effectively
Simulated images show how the cubes with more intricate fractal void patterns dissipate shock waves more effectively
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Simulated images show how the cubes with more intricate fractal void patterns dissipate shock waves more effectively
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Simulated images show how the cubes with more intricate fractal void patterns dissipate shock waves more effectively

The microscopic structure of a material plays a huge role in how well it absorbs impacts, and now researchers at Los Alamos National Laboratory have hit upon a structure that works particularly well. The team 3D-printed cubes with fractal voids inside them, which could be a useful structure for new materials in helmets, armor and other protective items.

Materials that need to be shock-resistant are usually structured with gaps to help dissipate the shock waves. But the exact shape of these structures is still being experimented with, as researchers test “nanofoam”, herringbone, honeycomb, and microlattice patterns, among many others.

For the new study, researchers at Los Alamos investigated fractals. These intricate patterns consist of structures that repeat on smaller and smaller scales, and in this case that meant cubes with hollowed-out pores dotted through them.

The team 3D-printed plastic cubes with fractal voids carved into them, with varying levels of detail. Then, they tested how well each design withstood shock by firing impactors into them at about 670 mph (1,078 km/h).

The researchers found that the more intricately structured the cubes, the better they were at dissipating shock waves. Some of them were as much as five times better at the job than solid cubes made of the same material.

The team says that this structure of fractal void cubes could inform new protective materials for vehicles, helmets, body armor, and other things that might need to withstand shock waves.

That said, the researchers acknowledge that the current design isn’t necessarily the most effective. Next up, the team is investigating other void shapes and structures with the help of optimization algorithms.

“The goal of the work is to manipulate the wave interactions resulting from a shockwave,” says Dana Dattelbaum, lead author of the study. “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.”

The research is due to be published in the journal AIP Advances.

Source: Los Alamos National Laboratory

2 comments
zr2s10
I think truss shaped would work best. Or round. Squares transmit more along the straight edges in direction of impact. Trusses (triangles) would redirect impact in two directions. Round or elliptical might work, if you can manage packing density. I'd love to get a 3D printer and tinker with this stuff myself.
oldpistachio
me ride a bike - me watch NFL - me wonder what the thickness of the tested experimental was. Will the shock wave dissipate somewhat in just the shallow thickness the shell of a bike or motorcycle or football helmet? The words of the article imply a fractal, non-symmetrical pattern to be best, but then images are of symmetrical, square-based patterns (tangent: the brain-saving anti-shock strategies of woodpecker anatomy was being studied ... read that a couple years back, sry) re: disarming "shock waves," I wonder if Oakland CA's elevated highway collapse in the 1989 earthquake might? have been a bit less disastrous? if the supports were located irregularly i.e., maybe the uniform distance between the concrete supports coincided with, and intensified, the waves of the quake's ground swells and dips?