Re: [PSUBS-MAILIST] Steel Pipe Hull

["Øystein Skarholm" <skarholm@gmail.com>]

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 000kPa =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




************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003.  Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.

If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
	removeme-personal_submersibles@psubs.org

Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of
our server receiving your request.

PSUBS.ORG
PO Box 53
Weare, NH  03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************