[PSUBS-MAILIST] bolt in penetration

[Sean T. Stevenson via Personal_Submersibles]

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 is 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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