Putting Structural Material On A Diet

The albatross for transportation, in so many ways, is fuel: its cost, its volume, and its weight.

Sure, sci-fi movies show city-sized spacecraft wafting their interstellar courses as if they were wisps of smoke, but getting them off the ground is another matter altogether.

So the lighter the vessel, less force – and therefore less fuel – is needed. And engineers at the Massachusetts Institute of Technology and the Lawrence Livermore National Laboratory, or LLNL, think they have found the answer.

An account of the research by MIT uses the Washington Monument and the Eiffel Tower as examples of soaring architecture: one whose strength is based on heavy stone, the other based on an airy latticework of steel. All the MIT and LLNL engineers did was reduce this to a microscale.

They’ve designed a new system that could draw on many different materials, whether metals, ceramics or polymers, and they believe their structures may have achieved record rigidity for a given weight.

Such structures would be useful in any application that needs rigidity, strength and lightweight because of their low density. That would include spacecraft, of course, but also on smaller items such as smart phone batteries, which today make the devices almost unnaturally heavy.

Related Article: Latest Oil Train Derailment Adds Pressure For Stronger U.S. Action

The MIT and LLNL engineers made these micro-lattices with a highly precise 3-D printing technique called projection micro-stereolithography, which the two teams of engineers have been working on since 2008.

In “Ultralight, Ultrastiff Mechanical Metamaterials,” published in the June 20 issue of the journal Science, the researchers report that they overcame the weight issue by reducing density without making the structure weak and brittle, the way osteoporosis weakens bones.

Their MIT-LLNL materials, regardless of their nature, “can withstand a load of at least 160,000 times their own weight," said LLNL Engineer Xiaoyu “Rayne” Zheng, lead author of the article. "The key to this ultrahigh stiffness is that all the micro-structural elements … do not bend under [the] applied load.”

So how good is this material? According to the Science article, the MIT-LLNL materials are 100 times stiffer than other ultra-lightweight lattice materials previously reported in academic journals.

By Andy Tully of Oilprice.com