One of the new breakthrough research fields is the study of metamaterials. This is the name given to a group of artificial composites with unusual physical properties not found in natural materials. Linar Akhmetshin, a scientist at the Faculty of Physics and Engineering of Tomsk State University, conducted a series of experiments aimed at programming the properties of metamaterials and creating products with special functionality within the framework of the Security Technologies strategic project supported by the Priority 2030 federal program. The results of the study were published in the TSU Bulletin. Mechanics.
- A distinctive feature of metamaterials is that their properties do not depend on the chemical composition of the framework, but on the structure, which is arranged in a special way. Due to this, the response of a metamaterial to external impact will also be specific, says project leader Linar Akhmetshin, associate professor of the Department of Mechanics of Deformable Solid Bodies at the TSU Faculty of Physics and Technology. - We studied materials with a tetrachiral structure. Chirality is the property of an object not to overlap with its mirror image. The chiral structure gives the material unusual properties. For example, if you compress it along the Y axis, it will somehow shrink and twist in the X-Z plane. Ordinary materials do not behave this way.
Another even more interesting property of metamaterials is their ability to deflect and slow down light. The negative refractive index makes it possible to hide objects in one of the electromagnetic wave ranges. Therefore, in the future there may be airplanes that the radars will not be able to detect.
To manipulate the properties of metamaterials, we need to understand what happens when their structure changes. The material discovery can now also rely on computational approaches to quickly calculate the mechanical properties of possible materials. The design of metamaterial structure is ideally suited to numerical methods that can quickly and efficiently explore many possible geometric and structural solutions and verify them numerically.
The scientist applied compression to metamaterial samples. The regular unit cell of the metamaterial did not change its physical and mechanical properties under loading along three orthotropic axes. Various transformations of a cell (introduction of topological defects) led to changes in the properties, thus increasing or decreasing the effect.
- A defect is usually perceived with a minus sign, but in my study it is just a tool, which I used to obtain some new fundamental knowledge on metamaterials during compression and fracture of samples printed on a 3D printer, explains Linar Akhmetshin. - Thus, the rotation angle of a regular cell is 1.8°. The introduced topological defect reduced the rotation angle of a cell by more than 60% and significantly increased the stiffness of the material. The stiffness of the cell with the topological defect varies along the loading axis and becomes higher when the defect is located on the bottom side of a cubic sample.
New knowledge on metamaterials may be applied in various fields. For example, by programming materials, it is possible to attenuate or absorb vibration energy and thus create shock-protective structures with special strength. The use of such properties as negative refraction makes it possible to create new solutions in biomedicine, electronics and other fields.
Competent use of metamaterials may bring humankind to a new technological level. The study of the TSU scientist provides new fundamental knowledge, which is necessary to program metamaterials with new functions.
