Re: [PSUBS-MAILIST] acrylic cylinder

[Jon Wallace <jonw@psubs.org>]

Sean,

Thanks for that, I see the integer identifier on 753 now.  I still have 
some confusion however since I'm not sure what information the number of 
lobes at collapse is supposed to tell me from a design perspective.  I 
can extrapolate that there are more lobes at collapse for a smaller L/D 
value and a given t/D value.  But so what?  Does it matter how many 
lobes there are at collapse?

Looking at page 753, can you tell me if I am reading the chart correctly 
with the following information.
t/D = .04
L/D = .5
n=20,000 (approximately depending on how straight your eyes are)
psi = 770

Jon



Sean T. Stevenson wrote:
> L in this case is the spacing between two adjacent stiffeners.  There is no 
> consideration of total hull length.  (which makes sense, as a sufficiently stiff 
> cylinder / stiffener combination can be repeated as many times as you like to 
> create a hull of indeterminate length - buckling considerations aside).  Thus, 
> elastic instability of a cylinder supported by stiffeners spaced L apart 
> considers only two stiffeners in all cases - at either end of an otherwise 
> unsupported length of cylinder.  The integer identifier above each arc segment 
> on the graph is indeed the number of lobes anticipated at collapse, and you 
> will note it is labeled as such in the plot on page 753.
>
> -Sean
>   



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