What are the auxetic materials?

Auxetics are materials that have a negative Poisson ratio - when they are stretched, instead of thinner are thicker. This is possible because of their basic structure. One could imagine a foam made of millions of small cells in the shape of butterflies connected to each other. If someone pulls on the sides of the material, the bow ties spread to squares and expand on the transverse plane and the plane parallel to the stretching action. This phenomenon is caused by macrostructure or microstructure of the material and not by the chemical composition of the material itself, so many common materials can be inserted into auxetic arrangements, although materials that are flexible and stretched work best. Breaking field. The term "auxetic" was not used to indicate these materials until about1991. It was derived from the Greek word auxetikos , which means "what tends to increase".

No natural examples

auxetiMaterials are not natural and there are no known biological examples. The first auxetics were foams with specially modified microstructures. Depending on the size of the air gaps in the microstructure, the auxiliary effect in these materials may be more or less extreme. Most of the auxiliary foams are extended by a factor of about 30 percent before shredding due to stretching force. With more advanced auxetics structured at the molecular level, more impressive expansion may be possible.

Potential applications

proposals for the use of auxetics were relatively wide, although few implementations have actually been created since 2011. Auxetics used in small medical probes could be used to dilates blood vessels. These friendrials are so easily expanding that they would also be the ideal filters that could catch many foreign particles in their macrostructure. Unlike traditional filters, they could remain small and compact when not used.

Thrking auxetic fibers ProsBy composite composites, it could enable the strength to improve, and the tendency to expand under tension stretching helps maintain the overall composite structure together. This is especially true for composites consisting of materials that tend to slide around them. Many other potential applications for auxetics need to be developed, although the list is long and shows a great promise in many fields.