Football players (and anyone who gets hit hard) can breathe a sigh of relief. In recent research, engineers at the University of Colorado at Boulder and Sandia National Laboratory have developed a new packaging design that can withstand severe impacts. The team’s innovation, which can be printed on commercially available 3D printers, could one day be used on everything from shipping crates to football fields—anything that helps protect fragile objects or bodies from life’s impacts.

The team described the technology in a recent article published in the journal. Advanced Material Technologies.

“Mitigation is something that is important everywhere,” said Robert McCurdy, corresponding author of the study and the Paul M. Ready Associate Professor of Mechanical Engineering at CU Boulder. “This applies to protective barriers, knee pads and elbow pads, as well as packaging equipment.”

The study brings a new perspective to something most people have always encountered but rarely noticed: foam. These are soft materials filled with countless tiny holes and channels. Image of a bag of peanuts or stress balls. McCurdy said foams can be good shock absorbers, but they have a big drawback: If you compress the foam hard enough, it will eventually compress into a hard package.

He and his colleagues believe they can do better. In the new study, the team wrote computer algorithms to carefully redesign the interior of shock-absorbing materials, allowing them to bend under force, but only by following a careful pattern. When the group tested their design in the laboratory, they found that their floors could absorb 25% more force than today’s state-of-the-art technology.

“The material you use to absorb the shock makes a difference,” McCurdy said. “But it’s the geometry that really matters.”

Magnification

To understand why some pillows work and others don’t, it’s worth looking inside. For example, it’s all those little nooks and crannies that give foam its springiness. McCurdy explained that when you squeeze the sponge, these empty spaces begin to close, which absorbs the energy.

Some engineers went beyond the basic design. Instead, they create a tiling of a network of hexagonal towers, or “plate lattices,” that look a bit like a honeycomb. If a defender hits such a pad, the impact will cause the pads to collapse in a wave-like manner. This is a more effective way to absorb power.

But McCurdy notes that researchers have long tried to create flooring that meets the gold standard; This technology not only absorbs a lot of force, but can also absorb many different efforts with equal proficiency.

“If you are cycling and are involved in an accident, you don’t know whether it will happen at low speed or high speed. “But you expect your helmet to perform well no matter what,” he said. “We’re trying to develop a geometry that works well in all of these scenarios.”

allow compression

To make a more versatile pillow, the engineer and his colleagues decided to modify the interior of these objects to a scale of a millimeter or less. The group first used special software to create a network of cells, then arranged them to contain multiple folds, like bellows on an accordion. These folds help direct the honeycombs that crackle upon impact, providing a much smoother rolling.

“When you start compressing these structures, they absorb a certain amount of force,” McCurdy said. “The best shock designs maintain constant force throughout the compression range.”

In other words, unlike foam, these cushions will behave the same no matter how hard you press on them, or at least up to a certain maximum. The researchers also wanted to make sure their liner could withstand real-world bumps and bruises. They used a 3D printer to create small brick-sized blocks of a flexible material called thermoplastic polyurethane. Then they crushed it with an impact machine.

The group found that their blocks could absorb nearly six times more energy than standard foams made of the same material and up to 25% more than other cellular structures. McCurdy and his colleagues are now working to further refine their structure. He added that engineers can create similar structures from different types of materials, from flexible plastics to harder materials such as aluminum. In other words, the world could soon become a lot softer.