Re: pressure hull design (Fwd)

[John Brownlee <jonnie@chronic.lpl.arizona.edu>]

	You go down to the library and check out the following book(s):

	Roark, Raymond J. Formulas for Stress and Strain. McGraw-Hill,
1975. I think the current printing is the 5th or 6th edition.

	Nash, Dr. William J. Hydrostatically Loaded Structures:The
Structural Mechanics, Analysis and Design of Powered Submersibles.
Pergamon Press, 1995.
	
	Fluuge, Wilhelm . Handbook of Engineering Mechanics. McGraw-Hill
Handbooks, 1962. 

	I recommend the first two, and have only used the third for
back-of-the-envelope calculations at a library a few times. Others have
quoted it, so I include it here. Also you might grab a good text and/or
class on engineering mechanics/statics/strengths of materials.

	You might notice that these books, save the middle one, are older.
That is because this problem is one of the classics of materials
strengths, and should be pretty commonplace in any good statics or
engineering mechanics text. In particular, the Nash book has a pretty good
treatment of the effect out-of-roundness has on crush depth and treats
each hull design in a seperate chapter. It's always been hard to find, but
Barnes and Noble's mail-order shop has had a recent surplus of them. 

<DISCLAIM>
	-Do not- ever use these theoretical calculations of the crush
depth for a perfect sphere or cyllinder with hemi-heads to determine your
operational depth. Period. Ever. They are the absolute best-case, and real
spheres are always imperfect particuarly so if welded or machined without
relieving the strain produced during such fabbing. These imperfections,
which are not limited to geometry alone, cause significant decreases from
the theoretical crush depth.  
</DISCLAIM>
	
	Curious, I don't know anyone who fabs spheres or hemi's big enough
for this sort of exercise with the sort of out-of-round tolerance a
submersible of any depth necessitating spheres would call for. Anyone out
there have a shop to recommend? I'm a transplanted Easterner in Arizona,
and my network out here is pretty thin for big fab stuff in the west.
	Okay, I guess being in land-locked Tucson doesn't help either :)

							John

John Brownlee
Lunar and Planetary Lab
University of Arizona
jonnie @ lpl . arizona . edu