5 ms·

I wouldn't rule out extremely high internal pressures in static materials as a future research direction. Prince Rupert drops reach a pressure of 700 Megapasca

by lumost 6y ago

I wouldn't rule out extremely high internal pressures in static materials as a future research direction. Prince Rupert drops reach a pressure of 700 Megapascals, roughly 2-3 orders of magnitude less than the required pressure for this experiment. I'd imagine that more advanced processes and materials can already manage internal pressures substantially greater than the Prince Rupert Drop.

salty_biscuits 6y ago
It is hard to imagine a material strong enough to maintain residual stresses this high! Maybe in diamond? And what happens when it fractures and all comes apart? (unless it is contained in a very small volume so has bugger all potential energy)
- lumost 6y ago
  Looks like some recent synthetic diamonds manage pressure in the TPa regime! 1 order of magnitude higher than that required for this experiment. https://advances.sciencemag.org/content/2/7/e1600341 https://advances.sciencemag.org/content/2/7/e1600341
- peterwoerner 6y ago
  Materials do a little better under compression than tension. But yea, 267 GPa is a lot. The working stress for most high strength metals is about 1 GPa. With that being said under shock conditions for instance. That said you can locally get huge stresses without out breaking the material.
kortex 6y ago
I can readily imagine some cross-discipline techniques achieving this. A little lithography, some selective dissolution like Gorilla glass, perhaps some tricks from the optical fiber industry, and bam, you have a fine coaxial filament which creates a region of 100's-of -MPa stress along the length of the fiber. Maybe even GPa, though that's tensile-strength-of-nanotubes territory. Certainly it's years away but I dunno...This feels possible in an engineering sense.
- jojobas 6y ago
  >100's-of -MPa stress along the length of the fiber It's all fine and dandy until it breaks open, along the length, and releases not just the stored mechanical energy, but also all the inductive energy from the flowing current of few million amperes.
  - gfodor 6y ago
    I'd love someone smarter than me to do a back-of-the-napkin job on that. Are we talking a firecracker, a cherry bomb, a few kilos of TNT, or a MOBA?
    - jojobas 6y ago
      1 meter of 1mm diameter wire with 1 million amperes amounts to 750kJ, or ~180g of TNT. A superconductor blowing up across the length and distributing the energy doesn't seem as bad a whole transmission line's energy released at a point fault.
      - Already__Taken 6y ago
        that also sounds like pretty ok risks for an under sea cable. though given one break you have to replace the entire cable might cancel it out.
        cma 6y ago
        You could break it into sections connected by liquid nitrogen superconductors, or maybe extremely heavy gauge copper ones.
  - jlokier 6y ago
    Put two superconducting fibers next to each other with a thin insulating layer, or many fibers in a bundle. Have the supercurrent in one direction matched by the same supercurrent in the other direction, alternations as closely spaced as possible. The magnetic field will be confined, at least. When the fiber breaks, join the entwined superconductors together (equivalently: have the insulator break down), and the current in the rest of the transmission line can continue flowing. Coaxial variant also available.

by lumost 6y ago

salty_biscuits 6y ago

It is hard to imagine a material strong enough to maintain residual stresses this high! Maybe in diamond? And what happens when it fractures and all comes apart? (unless it is contained in a very small volume so has bugger all potential energy)

lumost 6y ago
Looks like some recent synthetic diamonds manage pressure in the TPa regime! 1 order of magnitude higher than that required for this experiment. https://advances.sciencemag.org/content/2/7/e1600341 https://advances.sciencemag.org/content/2/7/e1600341
peterwoerner 6y ago
Materials do a little better under compression than tension. But yea, 267 GPa is a lot. The working stress for most high strength metals is about 1 GPa. With that being said under shock conditions for instance. That said you can locally get huge stresses without out breaking the material.

kortex 6y ago

I can readily imagine some cross-discipline techniques achieving this. A little lithography, some selective dissolution like Gorilla glass, perhaps some tricks from the optical fiber industry, and bam, you have a fine coaxial filament which creates a region of 100's-of -MPa stress along the length of the fiber. Maybe even GPa, though that's tensile-strength-of-nanotubes territory. Certainly it's years away but I dunno...This feels possible in an engineering sense.

jojobas 6y ago
>100's-of -MPa stress along the length of the fiber It's all fine and dandy until it breaks open, along the length, and releases not just the stored mechanical energy, but also all the inductive energy from the flowing current of few million amperes.
- gfodor 6y ago
  I'd love someone smarter than me to do a back-of-the-napkin job on that. Are we talking a firecracker, a cherry bomb, a few kilos of TNT, or a MOBA?
  - jojobas 6y ago
    1 meter of 1mm diameter wire with 1 million amperes amounts to 750kJ, or ~180g of TNT. A superconductor blowing up across the length and distributing the energy doesn't seem as bad a whole transmission line's energy released at a point fault.
    - Already__Taken 6y ago
      that also sounds like pretty ok risks for an under sea cable. though given one break you have to replace the entire cable might cancel it out.
      - cma 6y ago
        You could break it into sections connected by liquid nitrogen superconductors, or maybe extremely heavy gauge copper ones.
- jlokier 6y ago
  Put two superconducting fibers next to each other with a thin insulating layer, or many fibers in a bundle. Have the supercurrent in one direction matched by the same supercurrent in the other direction, alternations as closely spaced as possible. The magnetic field will be confined, at least. When the fiber breaks, join the entwined superconductors together (equivalently: have the insulator break down), and the current in the rest of the transmission line can continue flowing. Coaxial variant also available.