What do a flea and an eagle have in common? They can store energy in their feet without having to continuously contract their muscles to then jump high or hold on to prey. Now scientists at Queen Mary University of London and University of Cambridge have created materials that can store energy this way, be squeezed repeatedly without damage, and even change shape if necessary.
These kinds of materials are called auxetics and behave quite differently from regular materials. Instead of bulging out when squeezed, they collapse in all directions, storing the energy inside.
Current auxetic material designs have sharp corners which enable them to fold onto themselves, achieving higher density. This is a property that has been recognised recently in lightweight armour designs, where the material can collapse in front of a bullet upon impact. This is important because mass in front of a bullet is the biggest factor in armour effectiveness.
The sharp corners also concentrate forces and cause the material to fracture if squeezed multiple times, which is not a problem for armour as it is only designed to be used once.
In this study, published in Frontiers in Materials, the team of scientists redesigned the materials with smooth curves which distribute the forces and make repeated deformations possible for other applications where energy storing and shape-changing material properties are required.
The work lays the basis for designs of lightweight 3D supports, which also fold in specific ways and store energy which could be released on demand.
Principle investigator Dr Stoyan Smoukov, from Queen Mary University of London, said: “The exciting future of new materials designs is that they can start replacing devices and robots. All the smart functionality is embedded in the material, for example the repeated ability to latch onto objects the way eagles latch onto prey, and keep a vice-like grip without spending any more force or effort.”
The team expects its nature-inspired designs could be used in energy-efficient gripping tools required in industry, re-configurable shape-on-demand materials, and even lattices with unique thermal expansion behaviour.
Eesha Khare, a visiting undergraduate student from Harvard University who was instrumental in defining the project, added: “A major problem for materials exposed to harsh conditions, such as high temperature, is their expansion. A material could now be designed so its expansion properties continuously vary to match a gradient of temperature farther and closer to a heat source. This way, it will be able to adjust itself naturally to repeated and severe changes.”
The flexible auxetic material designs, which were not possible before, were adapted specifically to be easily 3D-printed, a feature the authors consider essential.
Dr Smoukov added: “By growing things layer-by-layer from the bottom up, the possible material structures are mostly limited by imagination, and we can easily take advantage of inspirations we get from nature.”
The Latest on: Auxetic materials
via Google News
The Latest on: Auxetic materials
- 3D Printed Cellular Fingers Offer Material Balance Required for Modern Roboticson August 2, 2019 at 2:28 am
Like other types of mechanical metamaterials, the NPR of auxetics is generally a direct consequence of the topology, where the joints rotate to move the structure,” state the researchers. NPR ...
- Tool turns flat sheets into 3D shapes like shoeson July 24, 2019 at 5:00 pm
Researchers 3D-printed the base of the shoe and fashioned the upper part from auxetic material. (Credit: Carnegie Mellon) “We’re taking a flat piece of material and giving it the tendency, or even the ...
- Inspired by nature: New body protection for BMW employeeson June 29, 2019 at 1:57 pm
The rind of the pomelo is one of these so-called auxetic materials, which responds completely differently to pressure than conventional structures: Where conventional material gives way and becomes ...
- RoCycle robot gets a feel for paper, metal and plasticon April 12, 2019 at 2:44 am
RoCycle’s motor-driven hand is made of an auxetic material that gets wider when stretched. The MIT team created auxetics that, when cut, twist to the left or right. Combining a ‘left-handed’ and ...
- This New Material Thickens as it Stretcheson April 4, 2019 at 6:44 am
In a study published in Nature Communications the researchers note these so-called “auxetic materials” can be found in nature in the skin of cats, in human tendons, and in the protective layer inside ...
- Scientists invented a new material that gets thicker as you stretch iton December 4, 2018 at 1:05 pm
The material, which is described in detail in a new paper published in Nature Communications, is one of few that exhibit “auxetic” properties, which means they expand instead of contracting when ...
- A bit of a stretch... material that thickens as it's pulledon December 4, 2018 at 7:52 am
Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching properties. Their findings are published today ...
- First synthetic auxetic material could expand into body armour and sportswearon December 4, 2018 at 6:55 am
Body armour, biomedical devices and next generation sportswear could all benefit from the first synthetic auxetic material to be discovered that becomes thicker as it is stretched. Liquid crystal ...
- Coincident molecular auxeticity and negative order parameter in a liquid crystal elastomeron December 4, 2018 at 2:32 am
Auxetic materials have negative Poisson’s ratios and so expand rather than contract in one or several direction(s) perpendicular to applied extensions. The auxetics community has long sought synthetic ...
via Bing News