Re: [PSUBS-MAILIST] Git Kraken stiffeners

["Sean T. Stevenson" <cast55@telus.net>]

Sorry, Frank, but I haven't been following your build very closely.  Do you 
have drawings / sketches of the assembly / parts you are discussing?  I can't 
suggest any specific fabrications without a better understanding of your 
specific problem.  More generally, off the top of my head I would suggest:

1) that the thick window seat / rings (not sure of your terminology here) be 
deep enough such that the curved hull shell within the seat, if it were not 
cut out at all, would be contained entirely between the window seat internal 
and external planes (ensuring continuity of load path),
2) that the shell surrounding the window seat be reinforced by an amount of 
material no less than that removed to accommodate the window,
3) that the aforementioned reinforcement be integral to the shell wall and not 
by means of a reinforcement plate / shell which adds thickness without 
complete fusion of the interface,
4) that any abrupt transitions in shell thickness, such as between the formed 
shell and the aforementioned reinforcement, be faired at no less than a 3:1 
taper (4:1 preferable), either by weld deposition or by a reinforcement 
formed/cast/trimmed to shape
5) that the abrupt transition in thickness between the shell or reinforcement 
and the stiff window seat be designed to minimize stress concentration either 
by the incorporation of a gradual transition, or by a fillet of appropriate 
radius.

-Sean


On November 3, 2009 16:56:48 ShellyDalg@aol.com wrote:
> Hi Guys. I'm casting around for some ideas on how best to add depth to the
> hull at the window area.e
> The main stiffener ribs are still not resolved but the windows need some
> stuff.
> Any thoughts ( good or bad ) are welcome.
> I'm leaning toward replacing the main window assembly with a 1 inch thick
> sleeve.This will still leave me with a 19 inch viewing area by expanding
>  the hole a little and a thicker sleeve. This could be done next winter.
> 
> The two smaller windows are 16 inch dia. sleeves  ( ID ) and the 1  inch
> thick base ring inside the sleeve is more or less directly adjacent to 
>  where the hull connects to the sleeve. If I add a 1/2 inch thick by 2 or 3
>  inch wide band around the window sleeves this will pretty much replace all
>  the metal  that was cut out for the window hole. It's bound to stiffen the
>  area and it's  fairly easy to do if done on the outside.
> Although not completely full thick steel, that will make the area around
> the two smaller windows 7/8 inch thick.
> Any thoughts on this latest hair brained idea?
> I'm taking Hugh's advice and will see if I can get an engineering student
> locally to run some FEA on this and maybe some other ideas.
> It just seems like having that 1 inch thick ring across from where the hull
>  connects that it would prevent the "squeeze" stress on the window sleeve.
> With a  1/2 inch doughnut ring added, it's getting stronger than the hull
> with no  hole.
> Still thinking on this whole thing.
> Frank D.
> 



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