�Elastic buckling� honeycomb structures bounce right back from major impacts The concept of impact resistance likely brings to mind vehicle airbags, trampolines, helmets, kneepads, and other protective gear, but Cockrell School of Engineering (University of Texas-Austin) researchers, led by mechanical engineering professor Dr. Carolyn Conner Seepersad and research scientist Michael Haberman, are seeking to make such items more protective than ever before. The solution? Elastic buckling honeycomb structures.Known officially as negative-stiffness honeycombs, these hexagonal cell structures are so named because they are able to provide continued support from repeat impact events. Current traditional honeycomb structures can support an individual only once before breaking down and deforming permanently due to plastic buckling. Elastic buckling honeycomb structures provide the materials needed so that a given item could stretch or bend and protect a victim or item when necessary, but return to its normal shape afterward without any inward breakdown of its parts.The idea is credited to Germany Karlsruhe Institute of Technology professor Dr. Martin Wegener, who first dabbled into cloaking before he stumbled upon negative stiffness honeycombs last year. In fact, Leiden University PhD student Bastiaan Florijn created a sponge-like object as a prop for the concept at the American Physical Society March Meeting, with punched holes that are either vertical or horizontal in direction. Wegener work, picked up by Florijn to produce a rubber material that could make items beneath it �unfeelable,� spun an idea with French physicists who decided to make the ground its own elastic buckling device and drill holes that proved earthquake-resistant and absorbed impact energy.Now, University of Texas-Austin (UT-A) researchers are using Wegener work (and that of others) to apply negative stiffness to ballistics by using nylon (rather than a sponge) as their build material. So far, the UT-A team has created 3.5-inch prototypes that prove resilient under pressure: They can absorb the impact of a fastball traveling at a speed of 100mph in 0.03 seconds. The US Department of Defense provided a research grant for the team last year, enhancing the potential of this technology for both military and consumer applications. �Whether you�re serving our country in uniform, playing in a big game, or just driving or biking to work, the potential for multiple collisions or impacts over time � however big or small � is a reality,� Seepersad said in a statement.Leiden University student Florijn dreamed of �malleable� car bumpers at that time. �Imagine a car bumper that you can program � for instance, if you drive in a neighbourhood with a lot of small kids, you want to have a very soft bumper. But then if you�re going fast on the highway, you want it to be stiff,� he said.