Led by Chiara Daraio, professor of mechanics and materials, the researchers made the structure, which has a lattice spacing of around 3.5mm, out of plastic using a 3D printer. Inside the lattice they embedded steel cubes that act as resonators.
“Instead of the vibrations travelling through the whole structure, they are trapped by the steel cubes and the inner plastic grid rods, so the other end of the structure does not move,” explained Kathryn Matlack, a postdoc in Daraio's group.
Materials for absorbing vibrations already exist. In vehicles, machines and household appliances, vibrations are partly absorbed using special, mostly soft materials. The ETH researchers' vibration-absorbing structure is different because it is rigid and can thus also be used as a load-bearing component.
Also, compared to existing, soft absorption materials, the ETH team’s lattice structure is said to absorb a wider range of vibrations, both fast and slow, and is claimed to be particularly good at absorbing relatively slow vibrations. “The structure can be designed to absorb vibrations with oscillations of a few hundred to a few tens of thousand times per second”, explained prof Daraio. “This includes vibrations in the audible range. In engineering practice, these are the most undesirable, as they cause environmental noise pollution and reduce the energy efficiency of machines and vehicles.”
In theory, it would be possible to build such a construction out of aluminium and other lightweight metals instead of plastic, Matlack added. In principle, it would just require a combination of lightweight material, structured in a lattice geometry, and embedded resonators with a larger mass density. The geometry of the lattice structure and the resonators would need to be optimally aligned to the anticipated vibrations.
The team says its vibration absorbers are essentially ready for technical applications, but they are limited insofar as 3D printing technology is mostly geared toward small-scale production. The material properties, such as the load-bearing capacity, cannot yet match those of components manufactured with traditional methods. Once this technology is ready for industrial use, the team says it is confident that there is nothing to stand in the way of broader application of the material.
