4 ms·
What you need is a material with very high ultimate tensile strength. Carbon nanotubes might do it. Let's check. To compute the burst pressure of a pipe, we ca
by semi-extrinsic 7y ago
What you need is a material with very high ultimate tensile strength. Carbon nanotubes might do it. Let's check.
To compute the burst pressure of a pipe, we can use Barlow's formula:
P_max = S * T /R
where T is wall thickness, R is radius of the outside of the pipe, and S is ultimate tensile strength. Here T=R is the limit where the inside radius is zero. So the best case is
P_max = S/1.0000001
Carbon nanotubes are the highest strength material, with a theoretical S=100 megabar. So not possible, sadly.
- MayeulC 7y agoBut 2 million bars = 2 Mbar. Surely 100 Mbar is enough, or did I miss something?
- semi-extrinsic 7y agoBah, I messed up the Pascal-bar conversion in the text. Carbon nanotubes have S = 100 GPa = 1 Mbar. Too late to edit now. Thanks for catching this.
- davidhyde 7y agoThanks for these numbers! Can such pressures be attained by other means rather than permanent confinement? For example, the near wall pressure of a collapsing ultrasound bubble reaches about 100 MPa. Three orders of magnitude too little but can this technology be used to achieve much higher pressures? If so I wonder if maintaining an aggregate of material at high pressure (a high pressure foam as it were) would be sufficient to achieve bulk superconductivity.
- deleted 7y ago[deleted]
- bArray 7y agoThis is far outside my wheel house, but... Surely it's the pressure differential that dictates the burst pressure? So if you had multiple sleeves, each decreasing in pressure as you get closer to the outside, this could be possible?
- saagarjha 7y agoI'd expect that for a pipe under high pressure but small pressure differential compressive strength would matter much more than tensile strength.
- semi-extrinsic 7y agoYes, it's the pressure differential that matters, but I don't think it helps in practice. Each pipe needs to have a ratio of inner to outer diameter of at least 100. If the innermost radius is 1 mm, at three layers the outside radius of the biggest pipe is 1 kilometer.
- bufferoverflow 7y ago> Carbon nanotubes are the highest strength material That we can produce. I once asked my chemistry teacher if it's possible to make square carbon lattice, and he didn't have an answer. | | | ─ C ─ C ─ C ─ | | | ─ C ─ C ─ C ─ | | | ─ C ─ C ─ C ─ | | | EDIT: looks like both Carbyne and boron nanotubes are stronger than carbon nanotubes.
- VygmraMGVl 7y agoA square carbon lattice would be very unstable. Carbon can support up to 4 single bonds, but they have to be arranged in a tetrahedral symmetry (sp3). 4-member carbon rings exist in some compounds, but they are unstable and reactive. Flat carbon sheets exist as graphene, which is a hexagonal grid rather than your square one.