Materials science undergraduate student here (not a mechanical engineer, my knowledge is limited in the area, I did not go to great lengths to ensure I’m right here, etc.).
A typical method to generate high pressures in research are diamond anvils. This is suitable for exploring the behavior of cells and microorganisms under high pressure.
For human preservation, however, you’d need a pressure vessel. As the yield strength of your typical steel is on the order of 100, maybe 300 MPa, you’re really up against a wall here, materials-wise. I don’t doubt that suitable alloys for human-sized pressure vessels at 350 MPa exist, however, such vessels will be expensive, and controlling processes within will be difficult. In any case, generating such pressures will probably not involve a moving piston.
I can’t really tell whether or not the procedure you’ve outlined is viable, but I’m quite sure it’s far from trivial, just from an engineering point of view.
That’s an interesting observation! When I was looking into this, I found several suppliers[1][2][3][4] that claim to produce pressure vessels, tubing, and pumps all the way up to 150′000 psi (1GPa). If 300MPa are already pushing the boundaries of steel, do you know what they could use to achieve such pressures?
To my understanding it’s because of the higher tensile strength of carbon fiber, although I could be wrong.
I wonder, how much can be achieved by merely increasing the thickness of the walls (even to such extremes as a small hole in a cubic meter of steel)?
In a round vessel containing pressure, a pressure gradient is set up from the inside wall to the outside. You can think of such a vessel as a series of concentric shells of increasing radius, each of which only has to support the pressure differential acting upon it. At some pressure level, this pressure differential itself becomes so high that it tears the material apart, regardless of how thick the walls are or how tiny the interior radius is. The physics of this isn’t terribly complicated but I don’t have any links at the moment, sorry.
Sure, I can easily imagine that by mentally substituting steel with jello—at some point you’re tear it apart no matter how thick the walls are. However, that substitute also gives me the impression that most shapes we would normally consider for a vessel don’t reach the maximum strength possible for the material.
Most vessels are spherical or cylindrical, which is already pretty good (intuitively, spherical vessels should be optimal for isotropic materials). You might want to take a look at the mechanics of thin-walled pressure vessels if you didn’t already.
It’s important to note that the radial stresses in cylindrical vessels are way smaller than the axial and hoop stresses (which, so to say, pull perpendicular to the “direction” of the pressure). This is also why wound fibers can increase the strength of such vessels.
Thanks for taking the time to write this up and putting numbers to things: it makes it actually possible to evaluate your idea critically.
The thing that jumped out at me was the amount of pressure required for human preservation. What kinds of devices can generate 100KBar of pressure?
Edit: changed GBar to KBar
Materials science undergraduate student here (not a mechanical engineer, my knowledge is limited in the area, I did not go to great lengths to ensure I’m right here, etc.).
A typical method to generate high pressures in research are diamond anvils. This is suitable for exploring the behavior of cells and microorganisms under high pressure.
For human preservation, however, you’d need a pressure vessel. As the yield strength of your typical steel is on the order of 100, maybe 300 MPa, you’re really up against a wall here, materials-wise. I don’t doubt that suitable alloys for human-sized pressure vessels at 350 MPa exist, however, such vessels will be expensive, and controlling processes within will be difficult. In any case, generating such pressures will probably not involve a moving piston.
I can’t really tell whether or not the procedure you’ve outlined is viable, but I’m quite sure it’s far from trivial, just from an engineering point of view.
The concerns of user passive_fist are also valid.
That’s an interesting observation! When I was looking into this, I found several suppliers[1][2][3][4] that claim to produce pressure vessels, tubing, and pumps all the way up to 150′000 psi (1GPa). If 300MPa are already pushing the boundaries of steel, do you know what they could use to achieve such pressures?
One common technique is composite construction with carbon fibers wound concentrically around an alloy core.
Is that done to convert shear force to tension?
I wonder, how much can be achieved by merely increasing the thickness of the walls (even to such extremes as a small hole in a cubic meter of steel)?
To my understanding it’s because of the higher tensile strength of carbon fiber, although I could be wrong.
In a round vessel containing pressure, a pressure gradient is set up from the inside wall to the outside. You can think of such a vessel as a series of concentric shells of increasing radius, each of which only has to support the pressure differential acting upon it. At some pressure level, this pressure differential itself becomes so high that it tears the material apart, regardless of how thick the walls are or how tiny the interior radius is. The physics of this isn’t terribly complicated but I don’t have any links at the moment, sorry.
Sure, I can easily imagine that by mentally substituting steel with jello—at some point you’re tear it apart no matter how thick the walls are. However, that substitute also gives me the impression that most shapes we would normally consider for a vessel don’t reach the maximum strength possible for the material.
Most vessels are spherical or cylindrical, which is already pretty good (intuitively, spherical vessels should be optimal for isotropic materials). You might want to take a look at the mechanics of thin-walled pressure vessels if you didn’t already.
It’s important to note that the radial stresses in cylindrical vessels are way smaller than the axial and hoop stresses (which, so to say, pull perpendicular to the “direction” of the pressure). This is also why wound fibers can increase the strength of such vessels.
350 MPa is about 3.5 KBar, not 100 GBar.