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So this is just saying that the shape of a material determines its strength? From what I gathered from the video, they didn't actually use graphene in these ob

So this is just saying that the shape of a material determines its strength? From what I gathered from the video, they didn't actually use graphene in these objects. I was reading a introductory book on metallurgy over the holidays and realized that I had no idea what "stretching" was. I still hardly have any idea, but from what I was able to gather from the book, in steel at least, when stretched, there are these molecular "fault-lines" that can shift and still stay stable without actually breaking. Apparently, steel can be put under stress to fall to this final state to avoid further shifting during use in machines and whatnot. Maybe I'm completely missing the point and the plastic is somehow stronger than steel, but the quote >"You can replace the material itself with anything," MIT's head of Civil and Environmental Engineering said. "The geometry is the dominant factor." makes me think that this is the case?

biot 10y ago
Ironically, they could replace the graphene with steel and end up with steel being ten times stronger than steel.
gene-h 10y ago
What they are likely referring to here is strength to weight ratio. By more intelligently distributing material in space, one can get a higher strength to weight ratio than using solid material. Of course geometry does in fact influence material strength. One way geometry can influence material strength is by making crack propagation more difficult. In a simple plane sheet, a small crack at one end can easily propagate to the other end of the sheet resulting in failure. However, if we put a number of holes in our sheet, it becomes more difficult for the crack to propagate. A new crack has to be made each time the crack crosses one of the holes. Now this result of an additively gyroid structure having a high strength is a bit comical. One of the first 3d printing artists produced a sculpture of the gyroid a while back[0] and in fact the files for said sculpture are well known[1] and have been used to test 3d printers. It's sort of funny no one thought to crush one till now! [0]https://www.bathsheba.com/math/gyroid/ https://www.bathsheba.com/math/gyroid/ [1]https://www.bathsheba.com/downloads/ https://www.bathsheba.com/downloads/
Chris2048 10y ago
But the article says: > In its two-dimensional form, graphene is thought to be the strongest of all known materials Doesn't this imply it is stronger than steel in 2 dimensions?
- knicholes 10y ago
  I think this implies that GRAPHENE is stronger than steel, but this 3d printed thermoplastic is definitely not stronger than steel given the same shape.
  - Chris2048 10y ago
    What I mean is "in 2 dimensions" may be relevant, since the shape seems to be a 2D sheet folded into 3D space.

biot 10y ago

Ironically, they could replace the graphene with steel and end up with steel being ten times stronger than steel.

gene-h 10y ago

What they are likely referring to here is strength to weight ratio. By more intelligently distributing material in space, one can get a higher strength to weight ratio than using solid material. Of course geometry does in fact influence material strength. One way geometry can influence material strength is by making crack propagation more difficult. In a simple plane sheet, a small crack at one end can easily propagate to the other end of the sheet resulting in failure. However, if we put a number of holes in our sheet, it becomes more difficult for the crack to propagate. A new crack has to be made each time the crack crosses one of the holes. Now this result of an additively gyroid structure having a high strength is a bit comical. One of the first 3d printing artists produced a sculpture of the gyroid a while back[0] and in fact the files for said sculpture are well known[1] and have been used to test 3d printers. It's sort of funny no one thought to crush one till now! [0]https://www.bathsheba.com/math/gyroid/ https://www.bathsheba.com/math/gyroid/ [1]https://www.bathsheba.com/downloads/ https://www.bathsheba.com/downloads/

Chris2048 10y ago

But the article says: > In its two-dimensional form, graphene is thought to be the strongest of all known materials Doesn't this imply it is stronger than steel in 2 dimensions?

knicholes 10y ago
I think this implies that GRAPHENE is stronger than steel, but this 3d printed thermoplastic is definitely not stronger than steel given the same shape.
- Chris2048 10y ago
  What I mean is "in 2 dimensions" may be relevant, since the shape seems to be a 2D sheet folded into 3D space.