Materials Science- More Than Meets The Eye


Two scientific reports this past week highlight advances in materials science and their potential impact on the environment. Jeff highlighted how nano-research into concrete could cut carbon dioxide emissions up to 10%. In a different story, Walter Drugan from UW-Madison, has developed a proof that states we can create composite materials that are stiffer (under static load) then their component parts! Composite materials, like concrete, bricks and plywood, are made out of different materials that are combined together. Materials scientists had long thought that the only way to get a stiff material was to use other stiff materials. Six years ago a UW-Madison physicist, Roderic Lakes, used dynamic loading techniques to show that it was possible to produce a stiffer composite material when one of the components actually had negative stiffness. Walter's proof adds to Lakes discovery by showing stiffness can be increased in a composite material by using a component with negative stiffness for static loading as well as dynamic loading.

"For example, if you give me two materials and one has one stiffness and the other has another stiffness, there are rigorous mathematical bounds that show that with these two materials, you cannot make a material that has a stiffness greater than this upper bound," explains Drugan. "However, all these theoretical limits are based on the assumption that every material in the composite has a positive stiffness; in other words, that every material is stable by itself."

"If you're suddenly able to greatly expand the range of properties that one of these materials can have, then you have a much wider range of possibilities for the overall composite. And that's what this research does. It says, 'You don't need to limit yourself to two stable materials anymore.'"

With a new understanding of how materials behave, we are better able to choose materials that are environmentally secure. This new proof may also help us understand how animals have made incredible materials from common at hand elements, and how we might go about mimicking them (biomimicry) in the future. :: Science a Go-Go.

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