Future protective clothing made of energy-absorbing metamaterial?

Researchers at the University of Massachusetts Amherst have developed a controllable elasto-magnetic metamaterial capable of absorbing large amounts of energy. In the future, it could be used in robotics and protective materials.

It is an artificial composite material that could be used in numerous applications due to its electromagnetic properties. The material is a rubbery, solid substance with embedded magnets. The material properties during phase transitions can be used to selectively release stored energy or absorb energy. Researchers have succeeded in fully controlling the phase transitions in both directions.

Professor Alfred Crosby of the University of Massachusetts explains, “Imagine a rubber band. You pull on it and when you let go, it flies through the room. Now imagine a super rubber band. When you stretch it to a certain point, you activate a surplus of energy stored in the material. When you release the rubber band, it flies a mile.”

“To amplify the energy release or absorption, you have to create a new structure at the molecular or even atomic level,” Crosby says. “But that’s a challenge, and it’s even more difficult to do it in a predictable way. By using metamaterials, we’ve overcome these challenges and not only made new materials, but also developed the design algorithms to program these materials with specific reactions so that they are predictable”

Xudong Liang, the lead author of the paper, currently a professor at Harbin Institute of Technology, Shenzhen (HITSZ) in China, who conducted this research as a postdoctoral fellow at UMass Amherst, says, “By embedding tiny magnets in the elastic material, we can control the phase transitions of this metamaterial. And because the phase shift is predictable and repeatable, we can design the metamaterial to do exactly what we want: either absorb the energy of a large impact or release large amounts of energy for explosive motion.”