Durham University engineers have been inspired by nature to create what they say is the first manufactured non-cuttable material.

They got the idea for the new lightweight material from the tough cellular skin of the grapefruit and the fracture resistant shells of the abalone sea creature.

The material – called Proteus after the shape-changing mythical god – could be used in the security and health and safety industries.

Metallic foam

It’s made from alumina ceramic spheres encased in a cellular aluminium, metallic foam structure and works by turning back the force of a cutting tool on itself.

In tests Proteus could not be cut by angle grinders, drills or high-pressure water jets.

When cut with an angle grinder or drill, the interlocking vibrational connection created by the ceramic spheres inside the casing blunts the cutting disc or drill bit.

The ceramics also fragment into fine particles, which fill the cellular structure of the material and harden as the speed of the cutting tool is increased

Ceramic spheres

Essentially cutting the material is like cutting through a jelly filled with nuggets – if you get through the jelly you hit the nuggets and the material vibrates in such a way that it destroys the cutting disc or drill bit.

Water jets are also ineffective because the curved surfaces of the ceramic spheres widen the jet to substantially reduces its speed and weaken its cutting capacity.

Our researchers say Proteus could be used to make bike locks, lightweight armour and in protective equipment for people who work with cutting tools.