The three-dimensional material has a regular ordered pyramid-and-cross cell geometry, unlike the typical 3D structures of different materials. For example, a honeycomb structure can withstand forces from one perpendicular direction but will collapse from forces from other directions. Isomax is designed to resist crushing and shearing forces from all directions.
Jonathan Berger, a materials researcher from University of California, Santa Barbara, studied the isotropic and geometric properties of 3D cellular materials and identified a low-density structure that would present a multitude of unique properties without compromising on structural integrity.
Along with materials scientist Haydn N. G. Wadley from University of Virginia, and materials and mechanical materials and mechanical engineering professor Robert McMeeking, Berger has proven that this unique geometry is the first of its kind to achieve the extreme possible performance limited only by theoretical bounds.
Their research is published in the journal Nature. As far as the matter in the geometry is concerned, it is a loosely defined combination of a stiff substance and air. “We were trying to answer the fundamental question of how to add space to stuff,” Berger said.
For instance, a hip replacement must be rigid enough to provide shape and sustenance, while the surface that touches the pelvis should be flexible and malleable enough to allow for weight bearing without grinding away at the socket.
“Jonathan’s achievement opens up opportunities to make structures that engineers will be able to exploit to improve things like implants, sandwich panels for structural stiffness and strength, and multifunctional devices like heat sinks that can also be stiff and strong,” said McMeeking. “His invention is also timely as new fabrication techniques such as 3-dimensional printing now make it possible to manufacture novel geometries such as the one that he has invented.”
Berger believes that the foam’s relatively simple design of regularly repeating cellular structures can be manufactured and scale to demand using origami like sheet folding and bonding methods.
“Because it has certain symmetries and alignments and achieves the theoretical bounds for stiffness, there is no other material like it,” said Berger. “Even if we found some of the materials later in the future, they would still be limited by the same bounds and they would still share the properties of this.”
For more materials news, find out how Recluse Spider Silk Offers Inspiration for Tougher Materials.