[PSUBS-MAILIST] help interpreting ABS rules
Alan via Personal_Submersibles
personal_submersibles at psubs.org
Mon Apr 27 13:08:59 EDT 2015
Jon,
have you looked at what G.L. says about the same issue.
It may give some clarification. (or not)
Alan
Sent from my iPad
> On 22/04/2015, at 7:08 am, Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> Given that there is copious distinction throughout the document differentiating heavy and non-heavy stiffeners, it could be that non-distinction in the definitions of equation variables means application to both. I notice that none of the variable definitions referencing stiffeners differentiates between heavy or non-heavy. What is the effect in the equation of assuming "I" refers to all stiffeners?
>
> Jon
>
>
> +++++++++++++++++++++++++++++++++
>
> SEAN STEVENSON WROTE:
>
> I found a bit of time this weekend to work on the hull optimization
> software, and was just revisiting the "Overall Buckling Strength"
> calculation in Section 6/19.13 of the 2014 ABS Rules for Building and
> Classing Underwater Vehicles, Systems and Hyperbaric Facilities, when I
> noticed the following:
>
> The limit pressure corresponding to the overall buckling mode between
> heavy support members is obtained from the following equation:
>
> Pn = (E*t/R)*A_1 + E*I*A_2/L*R^3
>
> The section goes on to define some of those terms, but what caught my
> attention was the "I" in the second term of this equation. The
> nomenclature "I" does not distinguish between "I" for a heavy stiffener
> or a regular stiffener in the rules - it is contextual. Given the
> purpose of the section, I had assumed that it meant "I" for a heavy
> stiffener, but the term in question also contains the term "L", or
> distance between stiffeners, which is distinct from "L_c", or distance
> between heavy stiffeners, leading to some ambiguity. If the second term
> is a correction for stiffness of the section in between heavy
> stiffeners, the "I" could very well be the "I" for a regular stiffener
> in between, but it isn't clear to me.
>
> Thoughts?
>
> Sean
>
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