Materials researcher and professor develop material that achieves the theoretical limit for high stiffness

isomax: the trade name of the metamaterial
Tuesday, February 21, 2017

From the article, "In great shape" in The UCSB Current, written by Sonia Fernandez: 

In 2015 UC Santa Barbara mechanical engineer and materials scientist Jonathan Berger developed an idea that could change the way people think about high-performance structural materials. Two years later, his concept is paying research dividends.

In a letter published in the journal Nature, Berger, with Robert McMeeking, a UCSB materials and mechanical engineering professor, and materials scientist Haydn N. G. Wadley from the University of Virginia, prove that the three-dimensional pyramid-and-cross cell geometry Berger conceived is the first of its kind to achieve the performance predicted by theoretical bounds. Its lightness, strength and versatility, according to Berger, lends itself well to a variety of applications, from buildings to vehicles to packaging and transport.                       

Called Isomax™, the beauty of this solid foam — in this case loosely defined as a combination of a stiff substance and air pockets — lay in the geometry within. Instead of the typical assemblage of bubbles or a honeycomb arrangement, the ordered cells were set apart by walls forming the shapes of pyramids with three sides and a base, and octahedra, reinforced inside with a “cross” of intersecting diagonal walls.

The combination of the pyramid and cross-shaped cells, said Berger, resulted in a structure that had low density — mostly air, in fact — yet was uncommonly strong for its mass. The shapes made it possible for the material to achieve the theoretical limit of isotropic elastic stiffness — the ability of a material to handle stresses in all directions equally well.

To read the entire article, please visit The UCSB Current. 

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