Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New mechanical metamaterials can block symmetry of motion, findings suggest

14.02.2017

Engineers and scientists at The University of Texas at Austin and the AMOLF institute in the Netherlands have invented the first mechanical metamaterials that easily transfer motion effortlessly in one direction while blocking it in the other, as described in a paper published on Feb. 13 in Nature. The material can be thought of as a mechanical one-way shield that blocks energy from coming in but easily transmits it going out the other side.

The researchers developed the first nonreciprocal mechanical materials using metamaterials, which are synthetic materials with properties that cannot be found in nature.


This is an artist's rendering of mechanical metamaterials.

Credit: Cockrell School of Engineering

Breaking the symmetry of motion may enable greater control on mechanical systems and improved efficiency. These nonreciprocal metamaterials can potentially be used to realize new types of mechanical devices: for example, actuators (components of a machine that are responsible for moving or controlling a mechanism) and other devices that could improve energy absorption, conversion and harvesting, soft robotics and prosthetics.

The researchers' breakthrough lies in the ability to overcome reciprocity, a fundamental principle governing many physical systems, which ensures that we get the same response when we push an arbitrary structure from opposite directions.

This principle governs how signals of various forms travel in space and explains why, if we can send a radio or an acoustic signal, we can also receive it. In mechanics, reciprocity implies that motion through an object is transmitted symmetrically: If by pushing on side A we move side B by a certain amount, we can expect the same motion at side A when pushing B.

"The mechanical metamaterials we created provide new elements in the palette that material scientists can use in order to design mechanical structures," said Andrea Alu, a professor in the Cockrell School of Engineering and co-author of the paper. "This can be of extreme interest for applications in which it is desirable to break the natural symmetry with which the displacement of molecules travels in the microstructure of a material."

During the past couple of years, Alu, along with Cockrell School research scientist Dimitrios Sounas and other members of their research team, have made exciting breakthroughs in the area of nonreciprocal devices for electromagnetics and acoustics, including the realization of first-of-their-kind nonreciprocal devices for sound, radio waves and light. While visiting the institute AMOLF in the Netherlands, they started a fruitful collaboration with Corentin Coulais, an AMOLF researcher, who recently has been developing mechanical metamaterials. Their close interaction led to this breakthrough.

The researchers first created a rubber-made, centimeter-scale metamaterial with a specifically tailored fishbone skeleton design. They tailored its design to meet the main conditions to break reciprocity, namely asymmetry and a response that is not linearly proportional to the exerted force.

"This structure provided us inspiration for the design of a second metamaterial, with unusually strong nonreciprocal properties," Coulais said. "By substituting the simple geometrical elements of the fishbone metamaterial with a more intricate architecture made of connected squares and diamonds, we found that we can break very strongly the conditions for reciprocity, and we can achieve a very large nonreciprocal response."

The material's structure is a lattice of squares and diamonds that is completely homogeneous throughout the sample, like an ordinary material. However, each unit of the lattice is slightly tilted in a certain way, and this subtle difference dramatically controls the way the metamaterial responds to external stimuli.

"The metamaterial as a whole reacts asymmetrically, with one very rigid side and one very soft side," Sounas said. "The relation between the unit asymmetry and the soft side location can be predicted by a very generic mathematical framework called topology. Here, when the architectural units lean left, the right side of the metamaterial will be very soft, and vice-versa."

When the researchers apply a force on the soft side of the metamaterial, it easily induces rotations of the squares and diamonds within the structure, but only in the near vicinity of the pressure point, and the effect on the other side is small. Conversely, when they apply the same force on the rigid side, the motion propagates and is amplified throughout the material, with a large effect at the other side. As a result, pushing from the left or from the right results in very different responses, yielding a large nonreciprocity even for small applied forces.

The team is looking forward to leveraging these topological mechanical metamaterials for various applications, optimizing them, and carving devices out of them for applications in soft robotics, prosthetics and energy harvesting.

###

This research received funding from the Air Force Office of Scientific Research, the Office of Naval Research, the National Science Foundation, the Simons Foundation and the Netherlands Organization for Scientific Research.

Media Contact

Sandra Zaragoza
Zaragoza@utexas.edu
512-471-2129

 @UTAustin

http://www.utexas.edu 

Sandra Zaragoza | EurekAlert!

Further reports about: asymmetry diamonds metamaterials prosthetics

More articles from Materials Sciences:

nachricht Game-changing finding pushes 3D-printing to the molecular limit
20.06.2018 | University of Nottingham

nachricht Creating a new composite fuel for new-generation fast reactors
20.06.2018 | Lobachevsky University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Creating a new composite fuel for new-generation fast reactors

20.06.2018 | Materials Sciences

Game-changing finding pushes 3D-printing to the molecular limit

20.06.2018 | Materials Sciences

Could this material enable autonomous vehicles to come to market sooner?

20.06.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>