Guys
According to: Timoshenko, S, Theory of elastic Stability, a very rough
calc gives me a crush depth for your cylinder will be:
L=1524mm, Rm=250,825mm, T=6,35mm,
k=4,167*10^-3, E=2,1*10^11Pa, m=R/T
1ATM=100 000Pa =10m
Pc=0,87*E*k/m^(3/2)
Pc=(0,87*2,1*10^11Pa*4,167*10^-3)/39,5^(3/2)
Pc=30,6kPa
Pc = 300m depth
This is without regards for out of roundness.
On 1/29/07, Jon Wallace <jon@psubs.org> wrote:
>
> Hi Doug,
>
> I think we need Cliff Redus to comment.
>
> I checked your spreadsheet and compared it to mine, and the difference was
> the center to center spacing of stiffeners. I left mine at the default
> value of 10 inches and you had changed yours to the length of the pipe (I
> assume) which is 60 inches. The output doesn't make sense to me either
> since I assumed a .0001 stiffener and web was essentially equal to not
> having a stiffener. The center to center spacing of stiffeners shouldn't be
> a factor in that case. I'm guessing there are some assumptions built into
> the formula's behind the spreadsheet geared towards a reasonably sized hull
> and it may not be applicable to pre-manufactured small diameter pipes
> without stiffeners.
>
> Hopefully Cliff will see this message and take a look himself.
>
> Jon
>
> -----Original Message-----
> From: owner-personal_submersibles@psubs.org
> [mailto:owner-personal_submersibles@psubs.org]On Behalf Of
> djackson99@aol.com
> Sent: Monday, January 29, 2007 12:12 PM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] Steel Pipe Hull
>
> Jon
>
> Your right about the stiffeners, but there must be other problems. Now I
> get 8 psi :) What are you using for "Center to center spacing of
> stiffeners"? When I change it the outcome changes, and that does not make
> any sense. Your calculation can not be right either; 57 psi for a 1/4"
> think 10 inch pipe? No Way! I get 57 psi out of a garden hose and I've used
> 10" steel pipes for temporary colverts and had concrete trucks drive over
> them. There is just no way they would not perform to anything less than
> 1500 feet.
>
> You can download my sheet from here:
> http://www.submarineboat.com/sub/BOB2_Hull_Calculation.xls
> to have a look if needed.
>
> I really do appreciate this exercise I hope the outcome is a simpler and
> more full proof approach.
>
> --Doug J
>
>
--
Vennlig hilsen
Øystein Skarholm