3D Printing Auxetic Materials | Two Minute Papers #96

Dear Fellow Scholars, this is Two Minute Papers
with Károly Zsolnai-Fehér. We are back! And in this episode, we shall talk about auxetic
materials. Auxetic materials are materials that when
stretched, thicken perpendicular to the direction we’re stretching them. In other words, instead of thinning, they
get fatter when stretched. Really boggles the mind, right? They are excellent at energy absorption and
resisting fracture, and are therefore widely used in body armor design, and I’ve read a
research paper stating that even our tendons also show auxetic behavior. These auxetic patterns can be cut out from
a number of different materials, and are also used in footwear design and actuated electronic
materials. However, all of these applications are restricted
to rather limited shapes. Furthermore, even the simplest objects, like
this sphere cannot be always approximated by inextensible materials. However, if we remove parts of this surface
in a smart way, this inextensible material becomes auxetic, and can approximate not only
these rudimentary objects, but much more complicated shapes as well. However, achieving this is not trivial. If we try the simplest possible solution,
which would basically be shoving the material onto a human head like a paperbag, but as
it is aptly demonstrated in these images, it would be a fruitless endeavor. This method tries to solve this problem by
flattening the target surface with an operation that mathematicians like to call a conformal
mapping. For instance, the world map in our geography
textbooks is also a very astutely designed conformal mapping from a geoid object, the
Earth, to a 2D plane which can be shown on a sheet of paper. However, this mapping has to make sense so
that the information seen on this sheet of paper actually makes sense in the original
3D domain as well. This is not trivial to do. After this mapping, our question is where
the individual points would have to be located so that they satisfy three conditions:
one: the resulting shape has to approximate the target shape, for instance, the human
head, as faithfully as possible two: the construction has to be rigid
three: when we stretch the material, the triangle cuts have to make sense and not intersect
each other, so huge chasms and degenerate shapes are to be avoided. This work is using optimization to obtain
a formidable solution that satisfies these constraints. If you remember our earlier episode about
optimization, I said there will be a ton of examples of that in the series. This is one fine example of that! And the results are absolutely amazing – the
possibility of creating a much richer set of auxetic material designs is now within
the realm of possibility, and I expect that it will have applications from designing microscopic
materials, to designing better footwear and leather garments. And we are definitely just scratching the
surface! The method supports copper, aluminum, plastic
and leather designs, and I am sure there will be mind blowing applications that we cannot
even fathom so early in the process. As an additional selling point, the materials
are also reconfigurable, meaning that from the same piece of material, we can create
a number of different shapes. Even non-trivial shapes with holes, such as
a torus, can be created. Note that in mathematics, the torus is basically
a fancy name for a donut. A truly fantastic piece of work, definitely
have a look at the paper, it has a lot of topological calculations, which is an awesome
subfield of mathematics. And, the authors’ presentation video is excellent,
make sure to have a look at that. Let me know if you have found this episode
understandable, we always get a lot of awesome feedback and we love reading your comments. Thanks for watching, and for your generous
support, and I’ll see you next time!

Author Since: Mar 11, 2019

  1. In the face deformation example I wonder whether it's possible to put singularities such that certain structures keep their mesh around. I.e. if you look carefully how the eyes of one face morph into the other, it looks like they are actually replaced by what previously was cheeks whereas the eyes become the brow, and the nose undergoes a similar such uncanny transformation.
    I wonder if that's "fixable".
    Meanwhile, in CG this would make an excellent method to depict a person morphing into another if it is meant to be uncanny.
    And of course, the materials that could be made from this are also sure to be highly interesting. I bet something similar could be achieved with sheets of graphene.

  2. Am I the only one who thought the initial parts of the video with the sphere and hands was 3D rendered as well?

  3. Thank you very much for this video and especially for the explanations. I'm studying flexure structures and also the chiral auxetic cellular and you open my mind a little more.
    Just a very big thank you because every millimeter that allows the elevation of the spirit and true knowledge and a victory against obscurantism.

  4. Where can you buy such material ,,,?,
    Or how to generate it from 3D software? Is anyone making it for sale? .. if so, where?

    —Finally sent to lasser court …—Thanks

  5. Did I understand that correctly? So this allows us to calculate the shapes we need to cut into a solid, flat material to form it into body armor? Like solid steel body armor that perfectly fits the shape of your body?

  6. So basically they had to make algorithm to UV map the objects before they could print the structure? slightly alter that and you could have a very useful tool for 3d artists. All the automatic UV tools i've tried produce undesirable results, and doing it by hand is tedious.

  7. can you guys train you AI to come up with auxetic material that would expand in every direction if pressure is applied from every direction?

  8. Am I understtand right? Auxetic more about geometry tweacks in some material than about material itself? This "supported materials" conclude me to some missunderstand I supose.

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