Scientists engineer uncuttable Proteus

An international research team from Europe, taking inspiration from nature, have devised a new aluminum-based material that turns the force of a cutting tool back onto itself.

This new lightweight material - named Proteus, after the shape-changing god in mythology - is made of ceramic spheres encased in a cellular aluminum structure, that in tests could not be cut by angle grinders, drills and even high-pressure water jets.

The research team, led by Durham University in the United Kingdom and the Fraunhofer Institute for Machine Tools and Forming Technology IWU in Germany, had a stroke of inspiration from the skin of grapefruits and the shells of mollusks.

"We were intrigued by how the cellular structure of the grapefruit and the tiled structure of mollusk shells can prevent damage to the fruit or the creatures inside, despite being made of relatively weak organic building blocks," said lead author Dr. Stefan Szyniszewski, assistant professor of applied mechanics in the department of engineering at Durham University. "These natural structures informed the working principle of our metallic-ceramic material, which is based on dynamic interaction with the applied load, in contrast to passive resistance."

Abalone sea creatures are built from tiles interlinked with a biopolymer material that makes them resistant to fractures.

To repel the most violent forcible entry tools, organic materials such as aragonite tiles-found in mollusk shells-were replaced in the new material with industrial, alumina ceramics and an aluminum metallic foam matrix.

"Essentially, cutting our material is like cutting through a jelly-filled with nuggets. If you get through the jelly you hit the nuggets and the material will vibrate in such a way that it destroys the cutting disc or drill bit," explained Szyniszewski.

As the material is made from a cellular aluminum structure, the jelly, wrapped around ceramic spheres, the nuggets, this has been found to be double destructive on cutting tools.

When cut with an angle grinder or drill, the vibrations created by the ceramic spheres inside the casing blunt the cutting disc or drill bit.

The interaction between the disc and ceramic spheres creates an interlocking, vibrational connection that purportedly resists the cutting tool indefinitely.

The blade is gradually eroded, and eventually rendered ineffective as the force and energy of the disc or bit is turned back on itself, it becomes weak and destroyed due to its own power.

"The ceramics embedded in this flexible material are also made of very fine particles which stiffen and resist the angle grinder or drill when you're cutting at speed in the same way that a sandbag would resist and stop a bullet at high speed," Szyniszewski said.

The ceramic fragments into fine particles, which fill the cellular structure of Proteus and harden as the speed of the cutting tool is increased due to interatomic forces between the ceramic grains.

This adaptive nature of Proteus further repulses force.

Additionally, water jets were found to be ineffective due to the curvature of the ceramic spheres that widen the jet, thus substantially reducing the speed and weakening the cutting potential.

"This material could have lots of useful and exciting applications in the security and safety industries. In fact, we are not aware of any other manufactured non-cuttable material in existence as of now," Szyniszewski added.

Presently, the researchers are awaiting patent approval for their material technology and hope to work with industry partners so it can be developed into products for the marketplace.

As to what those products will be, the team sees Proteus as an ideal option for protective gear and construction materials. It could provide a barrier against tools and accidental damage without the mass of traditional materials.

It may even show up in locks or safes that resist sawing, drilling, and other forms of cutting, perfect for bank vaults, high-security museums or even prisons.