Metamaterial can switch hard or soft

A versatile material, which is able to safely transition between rigid and soft, has been created that could be used in the construction of cars to help absorb impacts.

University of MichiganA new metamaterial, recreated here using K'Nex, can change its softness and hardness in response to low-level stress.

Scientists have discovered a way to produce a material that can switch between being hard and soft.

The so-called “metamaterial” can make the transition without risk of damage or alteration.

Two of the team’s suggested applications are bicycle tires that self-adjust to ride more easily on soft surfaces such as sand and cars which become soft during crashes to absorb the impact.

Metamaterials get their properties from the way they are constructed and not from what they are made of, enabling researchers to manipulate their structure to produce different characteristics.

Researchers at the University of Michigan have outlined how they can construct a metamaterial that allows the easy manipulation its surface to increase stiffness by an order of magnitude so great it is comparable with the difference between rubber and steel.

“The novel aspect of this metamaterial is that its surface can change between hard and soft,” said Xiaoming Mao, assistant professor of physics.

“Usually, it’s hard to change the stiffness of a traditional material. It’s either hard or soft after the material is made.”

Mao said the way an object comes in contact with the edge of the metamaterial changes the geometry of the material’s structure, and therefore how the material responds to stress at the edge. The material inside remains unaltered and undamaged.