Research results: new materials with multiple properties, which can be used in various scenarios

In our traditional cognition, a specific material often only possesses a specific attribute
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Because of this, this material can only be applied in one or a few fields, and does not have wider versatility
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So, is it possible to develop a new type of material that has multiple properties at the same time and can be used in multiple fields? Scientists all over the world have been exploring how to solve this problem
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Recently, researchers from the Massachusetts Institute of Technology (MIT) and the U.
S.
Army Research Laboratory (U.
S.
Army Research Laboratory) have successfully developed a new type of material with multiple properties.
This material is not only low in cost, but easy to use.
Manufacturing and assembly speed is also very fast
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They even collaborated with Toyota to produce a functional super-mileage race car
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The related paper, titled "Discretely assembled mechanical metamaterials", was published online in the scientific journal Science Advances in the form of a cover article on November 18
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(Source: Science Advances) Researchers say that just like bionics and integrated design, this new material will be a very powerful new tool that can help us "do more with less
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" Robots can produce large and complex objects, such as cars, robots, and wind turbine blades, by assembling sub-units composed of these materials
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The research was also supported by the National Aeronautics and Space Administration (NASA)
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Racing tests show unique potential.
In order to verify the potential of these materials to build large objects in the real world in a Lego-like form, the researchers worked with Toyota engineers to produce a functional ultra-mileage racing car, and earlier this year This racing car was shown at an international robotics conference in
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Figure｜ Functional ultra-mileage racing test site (Source: Toyota automotive society) Benjamin Jenett, one of the authors of the paper, said that they can assemble a lightweight and high-performance structure in just one month, while using traditional fiberglass buildings It takes a year to build a similar structure
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During the show, the street surface became smooth due to rain, causing the car to eventually hit an obstacle
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However, to everyone's surprise, despite the deformation of the grid-like internal structure of the car, it "rebounded" again, absorbing the shock caused by the impact, and hardly suffered any damage
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Jenett said that if it is a traditional car made of metal, the body may have been severely dented, and if it is a car made of composite materials, it may be broken
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This racing car truly demonstrates that these tiny parts can indeed be used to make human-sized functional devices
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Since the size and composition of these materials are basically the same, they can be combined in any desired way to provide different functions for more large-scale equipment
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In this regard, Dr.
Neil Gershenfeld, one of the authors of the paper, said: “We can use these materials to make a robot that bends in one direction but is rigid in the other direction, and it can only move in a specific way
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Therefore, with us Compared with the earlier work, the biggest change is its ability to combine the properties of a variety of mechanical materials.
Prior to this, people have always studied the application of a certain property
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" So, what is the four mechanical metamaterials? What kind of material can give the car this ability? Researchers call this new type of material "mechanical metamaterials".
The reason why they are named "metamaterials" is because their macroscopic properties are different from the microscopic properties of their constituent materials.

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In this work, they created four different types of micro-subunits, also called voxels, namely Rigid mechanical metamaterial, Compliant mechanical metamaterial, and Auxetic mechanical metamaterial and Chiral mechanical metamaterial
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Figure | Four voxels, of which gray is "rigid" voxel, purple is "soft" voxel, orange is "pulse" voxel, and blue is "chiral" voxel
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(Source: Science Advances) Voxels are assembled by injection-molded polymer flat frames.
Small and large, they can be combined into three-dimensional shapes, and then connected to larger functional structures.
Most of them will present an open The space provides an extremely light but hard assembly frame
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Among them, each type of voxel exhibits special properties that natural materials do not possess
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"Rigid" voxels are characterized by high strength and low weight
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(Source: Science Advances) The Poisson's ratio of "compliant" voxels is zero, which is a bit similar to the expansion characteristics
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But in this case, when the material is compressed, the side shape of the material will not change
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Few known materials can exhibit this performance
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Now, researchers can use new methods to produce this material
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(Source: Science Advances) "auxetic" voxels have an unusual characteristic
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When it is compressed, the cubic material does not actually expand to the side, but expands inward
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This is the first time that this material has been produced and demonstrated through traditional and inexpensive manufacturing methods
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(Source: Science Advances) "Chiral" voxels are characterized by twisting motion in response to axial compression or stretching
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Again, this is an unusual attribute
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(Source: Science Advances) At the same time, researchers can combine them to create devices that can respond to environmental stimuli in a predictable manner
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For example, aircraft wings or turbine blades, these devices respond to changes in air pressure or wind speed by changing their overall shape
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In this regard, Gershenfeld said, “Each of the material properties we showed was previously used in its own independent field, and scientists only conducted research based on one of these properties.
This is the first time that so many properties have been integrated into a system.
In the
wider application prospects, Jenett said, these materials are not only inexpensive, easy to manufacture, and fast to assemble, but they are also compatible with each other
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Therefore, they can possess many different types of peculiar properties at the same time, and play a good role in the same scalable and inexpensive system
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The key to this material being so special is that the structure composed of one such voxel will change in exactly the same way as the subunit itself exhibits when it is stressed
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This study proved that when the researchers assemble the parts together, all the connected places are "perfectly" coupled and become a continuous whole
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Jenett believes that an early application of this technology may be used to make wind turbine blades
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As the structure of wind turbine blades becomes larger and larger, transporting the blades to the job site has become a serious transportation problem, and if this kind of blade is assembled by thousands of tiny sub-units at the job site, it can be eliminated Transportation issues
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At the same time, due to the large blade size and lack of recyclability, the disposal of discarded turbine blades has also become a serious problem
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The blades made of tiny voxels can be disassembled on site and then reused to make other things
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In addition, the efficiency of the blades themselves will become higher, because they have a variety of mechanical properties, which can respond dynamically and homeopathically to changes in wind intensity
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This new material can also empower robots
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Today's robots are either rigid robots or flexible robots.
If a variety of mechanical properties are given to robots, perhaps robots will gain more unexpected capabilities
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"Now that we have this low-cost and scalable system, we can design any objects we want, such as quadrupeds, swimming robots, and flying robots.
The flexibility required for these objects is precisely what the system shows.
One of its main advantages
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” Jnett added
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For this research, Professor Amory Lovins of Stanford University said, “This technology can create low-cost, durable, and very lightweight aviation flight surfaces, just like bird wings, which can take advantage of the trend and continue to change their shape; In addition, it may also make the empty mass of the car closer to its payload, because their anti-collision structure is mainly air; it can even make the compressive strength of the spherical shell reach an unprecedented level, making the sky The net load lifted by the floating helium-free vacuum balloon is dozens of times
that of large jet aircraft .
” I believe that the emergence of this new material can give unlimited possibilities for future scientific research and life
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