Plastic fractal cubes containing many internal cavities of different scales dissipate impact energy several times more efficiently than the same solid targets.
The reaction of a material to an impact is largely determined by its microstructure. Scientists from the Los Alamos National Laboratory (LANL) have shown that fractal structures are capable of absorbing and dissipating shock energy especially efficiently. In the future, they can become the basis of a new generation of light armor, helmets, and other protective equipment.
When creating shockproof materials, the ability of internal cavities to dissipate energy is often used; porous and cellular structures are used along with layered ones. The authors of the new work found a way to implement this approach at once on several levels: the structures printed by them using a 3D printer had the form of a fractal cube, repeating themselves on an ever-decreasing scale.
An article by Dana Dattelbaum and her LANL colleagues is preparing to be published in AIP Advances magazine; briefly about their work is described in Los Alamos Reporter. During laboratory tests, such structures were affected by a projectile flying at a speed of more than 1000 km/h, showing that they were able to dissipate impact energy five times better than similar cubes, but without cavities.
In addition, the more microscopic the level the fractal structures of the material reached, the more efficiently he demonstrated himself. “The purpose of this work is to control the wave processes created by the shock wave,” says Dattelbaum. Therefore, now the authors plan to conduct more accurate calculations of the optimal geometry of the “fractal armor”, as well as to find methods to print them with the necessary accuracy.