Talk:Auxetics

Re: image issue

The image is a bit confusing, the stretching should be drawn perpendicular to how it is at the moment, then the hexagon becomes squarer as it is stretched, and therefore wider. I'll do a better series of drawings once my exams are done.

? I have to say, if the the image has any relationship to the article, I can't tell what it is. Why is it here? What is it trying to illustrate? Geoffrey.landis (talk) 16:13, 6 December 2007 (UTC)

The image is correct, but confusing. It is a hexagon which is becoming more square. Maybe additional arrows, and an improved caption would help. I can do the latter, but I don't know how to edit images on here. Septimus ii (talk) 11:19, 3 August 2011 (UTC)

Sorry, the image is definitely wrong!! Go to the German site of this article here it is drawn in the correct way! — Preceding unsigned comment added by 195.248.252.32 (talk) 11:42, 14 December 2011 (UTC)

image issue

The article states: "Auxetics are materials that become thicker in their perpendicular directions when stretched." The image shows the opposite, an object being stretched which has become thinner in the perpendicular direction.

J. Crocker 18:41, 1 August 2006 (UTC)

Possible vandalism alert

Slashdot recently linked to an article that prominently linked to this page on Wikipedia so keep your eye out for vandals. --froth^{T C} 07:43, 4 January 2007 (UTC)

And once again --Agamus 08:44, 6 December 2007

"Auxetics can be illustrated for timing of the elastic gain plus or minus the elasticity of the inverse object. Formulation of the elastic string will switch it to within the inverse tropication with an inelastic string hurled around an elastic cord." The part in italics sounds Vandalic to me (tropication isn't even a word), but I came here not knowing what auxetic means, so I would be the wrong person to correct it.--87.162.63.221 (talk) 10:40, 18 October 2008 (UTC)

I agree, looks "vandalic" (is that actually a word?) to me too, and while I too came here not knowing what auxetic means, I can see from the page history that the text you italicized was added by a user who was not logged and who left no edit summary, plus the previous version made sense, so I did change it --71.212.22.170 (talk) 01:48, 7 December 2008 (UTC)

New fabric with auxetic structure like a bungee cord

[[1]] Zetix is built around the principle of auxetics: objects that actually get fatter the more you stretch them....

To demonstrate how Zetix works, the best thing is to look how a thread behaves. When you jump from a bridge using a bungee cord, the force of gravity acting over your body weight will stretch it as you go down in free fall. While this happens, the cord threads will stretch getting closer together and making the cord get thinner as it expands through a larger distance.

However, if you coil a line around the bungee cord, something that defies logic will happen: the whole structure will get wider as it stretches. As you can see in the image, the line around the bungee cord becomes taut, making the bungee itself flex outward. This principle is called helical-auxetics. When you put two of these threads together, you have what Reed Richards would call an auxetic structure.Larry R. Holmgren (talk) 08:27, 7 December 2007 (UTC)

This example may be so, but it is not explained well in the actual article. Pictures or an animated gif would be useful."the inelastic string straightens while the elastic cord stretches and winds around it, increasing the structure's effective volume." This is confusing to try and visualise and a better example is needed. Even an explanation of the rectangular image would be more useful. Jazzvibes (talk) 02:49, 16 May 2011 (UTC)

References

Auxetic polymers: a new range of materials
Endeavour, Volume 15, Issue 4, 1991, Pages 170-174
Ken E. Evans

Sounds like a useful reference. —DIV (128.250.80.15 (talk) 02:15, 13 January 2009 (UTC))

Crystalline Materials

I question the idea that all these crystalline materials: "Li, Na, K, Cu, Rb, Ag, Fe, Ni, Co, Cs, Au, Be, Ca, Zn, Sr, Sb, MoS, BAsO and other." have a negative Poisson's ratio: take copper for example, which is regularly drawn into wires. Surely this wouldn't work if it EXPANDED in the othogonal directions to the stress. I suspect the linked papers refer to very specific, rare, crystal structures of these materials, rather than the materials in their common forms. Unfortunately cannot currently access these papers to check. 109.145.75.5 (talk) 10:16, 18 July 2022 (UTC)

Materials Scientist here. Correct, this statement is extremely misleading. Squeeze a cube of Cu, Ag, Fe, Ni, Co, Au, Zn and see what happens. If this statement was true, it would have made the iron and bronze ages...interesting. The papers cited do not support the statement. 134.84.164.224 (talk) 21:11, 30 September 2022 (UTC)

Please, therefore, edit the article to make it correct?

Captainllama (talk) 17:43, 1 October 2022 (UTC)