Elastic waves -- waves traveling across or through a solid material or a liquid without triggering any permanent changes to the substance's composition -- might be controlled to create military, medical and commercial applications, a scientist says.
Guoliang Huang, a professor of aerospace and mechanical engineering at the University of Missouri-Columbia, says those many applications could result from an ability to exert some degree of control over these waves.
Huang and his colleagues report in the journal Nature Communications that they've developed a material that can in fact control them.
"Our team has developed a material that, if used in the manufacture of new devices, could have the ability to sense sound and elastic waves," Huang says. "By manipulating these waves to our advantage, we would have the ability to create materials that could greatly benefit society -- from imaging to military enhancements such as elastic cloaking -- the possibilities truly are endless."
In the past, scientists have resorted to a combination of materials such as metal and rubber to accomplish 'bending' and control of elastic waves, but the UM team designed a material using a single component: steel.
Lasers were used to engrave a pattern of geometric microstructures into the steel that allow a negative refraction of such waves.
The result is an engineered structural material with the capability of controlling the amplitude of acoustical or elastic waves.
A number of possibilities using elastic waves and this material suggest themselves, Huang says, including acoustic devices, super-resolution sensors, and a superlens, courtesy of the material's ability to more directly focus the waves.
"Eventually, this can be a tremendous application in structure health monitoring, detecting damage. In its current state, the metal is a passive material, meaning we need to introduce other elements that will help us control the elastic waves we send to it," Huang says. "We're going to make this material much more active by integrating smart materials like microchips that are controllable."
Such a smart material would be able effectively "tune in" to any wave frequency and generate a desired response, a manipulation that would yield a way to control how the material reacts to what is surrounding it, he says.
Huang began his search for the new material 5 years ago when he was at the University of Arkansas-Little Rock, with funding from the U.S. Air Force Office of Scientific Research.
At the University of Missouri-Columbia since August, Huang has secured further funding from the Air Force to continue his work through 2017.
