Smart matter prototypes challenge Newton’s laws of motion
(Nanowerk News) For more than 10 years, Guoliang Huang, Huber and Helen Croft Chair in Engineering at the University of Missouri, has been investigating the unconventional properties of metamaterials – artificial materials that exhibit properties not commonly found in nature as defined by Newton’s laws of motion – in his long-term pursuit of designing the ideal metamaterial.
Huang’s goal is to help control “elastic” waves of energy that travel through larger structures – such as airplanes – without light and small “metastructures”.
“For many years I have been working on the challenge of how to use mathematical mechanics to solve engineering problems,” said Huang. “Conventional methods have many limitations, including size and weight. So, I’ve been exploring how we can find alternative solutions using lightweight materials that are small but can still control the low-frequency vibrations emanating from larger structures, such as airplanes.”
Now, Huang is one step closer to his goal. In a new study published in Proceedings of the National Academy of Sciences (“Active metamaterial for realizing odd mass densities”), Huang and colleagues have developed a prototype metamaterial that uses electrical signals to control the direction and intensity of energy waves passing through a dense material.
Potential applications of its innovative design include military and commercial uses, such as controlling radar pulses by directing it to scan a specific area for objects or managing vibrations created by air turbulence from an airplane in flight.
“This metamaterial has a strange mass density,” said Huang. “Thus, force and acceleration are not unidirectional, giving us an unconventional way to adapt the design of an object’s structural dynamics, or properties to challenge Newton’s second law.”
This is the first physical realization of an odd mass density, said Huang.
“For example, this metamaterial could be useful for monitoring the health of civil structures such as bridges and pipelines as an active transducer by helping to identify potential damage that may be difficult to see with the human eye.”