[PSUBS-MAILIST] bolt in penetration

[hank pronk via Personal_Submersibles]

Sean, 
Thank you, that is helpful.  My idea was to make the insert as tight as possible (sweat it in)  I am not sure if the difference in material would cause a problem though. The idea of seating the port into the shell a good option also.  I am just chewing the fat here, I have enough on my plate but it is fun to think about.  I was wrong about the size, the sphere is 6 feet and I wrote 60 in.  I imagine that kills the rating quite a bit?
Hank--------------------------------------------
On Sat, 1/10/15, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] bolt in penetration
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Saturday, January 10, 2015, 1:40 PM
 
 You could certainly do that, although a three inch
 thick shell is pretty substantial - I might consider
 machining eg. conical window seats in the hull shell
 directly, and then derating the hull to a depth whereby the
 actual hull thickness is the effective derated thickness
 plus the effective reinforcement, which just happens to be a
 contiguous shell.  The bolt-in arrangement would not act as
 hull reinforcement though - unless it was a force fit in the
 hole. The idea of reinforcements around openings is to
 provide material around the hole to carry the shell hoop
 stresses that would otherwise have passed through the
 material in the opening, such that you don't increase
 the nominal shell stress. This requires a (relatively)
 smooth load path to redirect stress around the hole. Brian
 recently asked me about the effectiveness of reinforcements
 like perpendicular flanges lining the hole, and this is a
 bit complicated, because some stress i!
  s indeed
 redirected into such a flange, but the load is not evenly
 distributed as you move inboard or outboard away from the
 hull shell (with diminishing returns at increasing
 distances), and you also introduce a stress concentration at
 the perpendicular transition. Ideally, reinforcements should
 be an effective thickening of the hull in the region
 immediately adjacent to the opening, tapered smoothly back
 (something like 4:1) into the hull shell to provide a
 continuous load path with no stress concentrations at abrupt
 changes in geometry.
 Sean
 
 
 
 
 On January 10, 2015 8:25:39
 AM MST, hank pronk via Personal_Submersibles
 <personal_submersibles at psubs.org> wrote:
 Is it feasible to have a
 bolt in penetration in a 3 inch thick sphere hull.  I am
 picturing machining a hole in the hull, then inserting a
 window housing with a shoulder(flange) that fits tight in
 the hole and is bolted in place.  Can that arrangement act
 as reinforcement for the hull.
 Hank
 
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