SMF Construction Process

> As Lucio correctly pointed out to me a few days ago, pressure
> vessels on earth are designed to contain more pressure than our
> stations or habitats.
>
> So getting it legally certified may be a completely different
> process.
>

No, it is basically the same.

15 psi versus 15,000 psi. The same equations are used, and the same
construction and inspection methods.

There are various MIL-STDs and ASME standards you can use, they offer
different combinations of test, analysis and inspection, depending on the
factor of safety. The lowest factor of safety is 1.4 for NASA STD pressure
vessels with extensive fracture mechanics. At the other end of the scale,
4.0 is the factor of safety required by DOT and ASME certifications..

>
> The way I see it, the atmospheric forces inside the "curved banana"
> torus will be exerting outward forces of less than 1 atm prssure.
> The structure and cladding of the torus must contain the atmosphere
> and resist those forces. We're not about talking a 'scuba tank' type
> pressure environment.

15 psi is fairly significant, especially when lives depend on it. Getting
safety certification for a non-standard pressure vessel design is very
expensive. It would be much cheaper to stick with a conventional design.

>
> Good point. The material for the torus must resist that. Perhaps the
> solution is to make the pressure skin thicker so as to resist the
> force of straightening out.
>

Well, yes. But that is the very problem. You do not want any bending
moments in a pressure vessel. You want pressure vessel walls loaded in
pure tension. A pressure vessel like a bent pipe has a large shear
stress, this is generally prohibited. Materials are much weaker in bending
than in tension. Making the walls much thicker is a major weight
penalty It is a lot lighter if you stick to a conventional design loaded in
pure tension.