[PSUBS-MAILIST] bow window

[Sean T. Stevrnson via Personal_Submersibles]

The calculation shown is using the section of the ABS rules that deals specifically with spherical shell hull components. The usage factor eta is specified by ABS as 0.67 for this calculation, which means the maximum allowable working pressure (maximum possible test depth) would be 0.67 of the critical pressure (predicted failure or crush depth). Safety factors over and above this (operating depth or actual test depth vs. maximum allowable) are left to the designer's discretion.

In which section is that temperature dependence discussed?

Sean


On November 15, 2014 1:50:09 PM MST, Hugh Fulton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>For windows ABS still has very different safety factors for the
>different temperatures though. i.e. at 24 deg S.F. 6 at 38 deg S.F. 8
>hence the query as to what you used for the 1.0 thick viewport for 500
>ft test. 
>
>The other thing I have always wanted to know is what temperature are
>the domes rated for that DW2000 uses and that the Perrys were designed
>for.   Hugh.
>
> 
>
> 
>
>From: Personal_Submersibles
>[mailto:personal_submersibles-bounces at psubs.org] On Behalf Of Sean T.
>Stevrnson via Personal_Submersibles
>Sent: Saturday, 15 November 2014 2:12 p.m.
>To: Personal Submersibles General Discussion
>Subject: Re: [PSUBS-MAILIST] bow window
>
> 
>
>Temperature doesn't really factor in to the calculations. Technically,
>seawater density is a function of both temperature and salinity (and
>very slight compressibility), but the user just enters an average value
>for density. Similarly, the shell material properties can be tweaked
>from the average values that are programmed in as defaults, to
>accommodate specific known material test values or just for increased
>conservatism. The calculations are assumed to be valid for any material
>within transition temperature limits, but no specific attempt is made
>to model creep in acrylic or toughness transitions in shell materials
>at extremely low or high temperatures. This software is just an
>implementation of the formulas presented in the ABS Rules. Simply put,
>if seawater is still liquid at your operating temperature, you're
>probably okay. The lack of perfect determinism at failure is why we h!
>ave safety factors.
>
>Sean
>
> 
>
>On November 14, 2014 2:50:52 PM MST, Hugh Fulton via
>Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>Sean,
>
>That is a very sexy programme you have there.  What temp do you have as
>standard for that calc?
>
>Regards,  Hugh
>
> 
>
> 
>
>From: Personal_Submersibles
>[mailto:personal_submersibles-bounces at psubs.org] On Behalf Of Sean T.
>Stevenson via Personal_Submersibles
>Sent: Friday, 14 November 2014 6:45 p.m.
>To: Personal Submersibles General Discussion
>Subject: Re: [PSUBS-MAILIST] bow window
>
> 
>
>On 2014-11-02 12:06, Vance Bradley via Personal_Submersibles wrote:
>
>Cliff, I'm thinking full hull diameter, 36" or thereabouts.
>
>Vance
>
>
>Vance - I was running some hull calcs for Brian Cox, so I ran a calc
>for your 36" d! ome port just to see... Looks like you could get away
>with one inch thick material for a 500' test depth.  
>Also - the calculator is designed for a full shell, so cut all the
>weight and buoyancy figures in half for a hemisphere.
>
>Sean
>
>
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