Re: [PSUBS-MAILIST] OSS (Pressure hull)

[Phil Nuytten <72020.572@compuserve.com>]

Hi, Dan:
        Yeah, Carsten's E is correct regards optimum volume/length ratios
as the major reason for elliptical heads or           'shallow' end-caps -
they are also easier to form in one piece without thinning at at the apex -
and they stack for shipping and storage. They're OK for internal pressure,
since the pressure keeps the 'skin' inflated - and the failure mode is
material yield. The same container under external pressure will usually
fail from asymetric buckling of the thin shell- unless you make it very
thick, which defeats the optimum weight/volume ratios available with
spherical end caps.
        Virtually any container will fail at some pressure, I 'spose . .But
even a seeming solid material can often be further 'compacted' even though
the point loading required may be greater than that found at the bottom of
Planet Ocean. When we made the hulls for the USN deep Newtsuits (4000 foot
design collapse) we (Hardsuits Inc.) had the torso machined on a 5 axis
mill/lathe from a billet of solid aluminum that had previously been brought
to red heat and 'pummeled' by an enormous hydraulic arm until it had
significantly reduced in volume - pretty wild to watch!
        We use a 500 ton press to have the 'fat squares' of which our
little bitty DeepWorker spheres are formed prior to welding. When the press
pushes the plate slowly into the form, a wisp of smoke comes off the steel
when the ram withdraws!!
Innerestin' stuff!
Phil Nuytten