Armor can be light, durable, and effective, but rarely all three at the same time. New research from the University of Texas Austin has a new solution: a honeycomb shape, but one durable enough to reform after impact.

Man-made honeycomb structures used in armor are light: the majority of the space inside them is air. They're also cheap, generally made from plastics. But the biggest problem with honeycomb shapes is that they're only good once: a single impact can collapse the whole structure, and then it has to be replaced with a new one. That's a frustrating flaw when it's a car bumper or a football helmet, and potentially deadly if it's in a soldier's helmet or reinforcing part of a military vehicle.

UT Austin's new approach is called a "negative stiffness" honeycomb. Instead of rigid hexagonal spaces, the grid is a series of cells, with cross beams and close-together parallel walls.