[PSUBS-MAILIST] K-250 Angle Stiffener Web Question

[Cliff Redus via Personal_Submersibles]

Steve, I agree with Sean's description of how a hole in the stiffener
affects the stress but from a practical perspective, I think if you placed
a few small diameter holes, say 1/4" diameter equally spaced around he
flange in the center of the web the impact would be negligible.  I would
have no problem doing this. Calculating the impact on crush depth would
be a pain in the butt as you would have to run full non linear FEA analysis
at design depth with and without the holes to see difference in stresses.
There would be a lot of other items that would be more likely to kill you
than this.

Cliff

On Thu, Sep 7, 2017 at 8:51 AM, Steve McQueen via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> All, as most probably know a K-250 has internal angle stiffeners (L).
>
> In my rebuild I have avoided drilling any holes in the web portion of
> these stiffeners (actually had some existing holes from the original build
> welded up/filled).  However, I am finding it would be nice if I could drill
> a few small (1/4") holes to help mount some interior parts. I believe I am
> looking at 1 to 3 of these holes max. in any single stiffener web.
>
> Calculating any reduction in functional strength that might result from a
> few small holes isn't straight forward.  I guess I am looking for some
> feedback from those who understand the web function of an L stiffener
> better than I.
>
> My guess is this wouldn't be a significant issue and I an being too anal.
>
> Thanks,
> Steve
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