[PSUBS-MAILIST] calculation

Tue Jul 7 18:01:48 EDT 2015

Alan,
When I was down diving with Karl Stanley earlier this year he showed me the veiwport that cracked. It was caused by him taking his sub to deep and the body warped putting side pressure on the veiwport. After that he derated his depth. This was on his first sub CBUG.
Thanks,
Scott Waters

Sent from my U.S. Cellular® Smartphone

-------- Original message --------
From: Alan James via Personal_Submersibles <personal_submersibles at psubs.org> 
Date:07/07/2015  4:27 PM  (GMT-06:00) 
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Cc:  
Subject: Re: [PSUBS-MAILIST] calculation 

Hank,
I remember Karl Stanley (or someone else) saying he cracked a dome at depth
due to an unexpected contraction of the pressure hull.
Just in case everything is not right; how about an unmanned dive!
You could record any noises by putting something like your cel phone in the hull
on record.
Then synchronize a watch on the support boat & record what depths you have
the sub down at at what times. So if you get a big "Crack" on your recording you 
will be able to tell at what depth it happened.
Easier said than done I know, but probably worth it.
Cheers Alan
From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Sent: Wednesday, July 8, 2015 12:26 AM
Subject: Re: [PSUBS-MAILIST] calculation

Alan,
When my dome made the mystery noise, I was at 100 feet deep. That puts about 18 tons on the dome.  I think it was either the straps were able to relax and find their happy place, or, the super cold water made the dome contract.
Hank--------------------------------------------
On Mon, 7/6/15, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Subject: Re: [PSUBS-MAILIST] calculation
To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
Received: Monday, July 6, 2015, 9:00 PM

Hank,I was
looking at some Deep Worker photos. The dome retaining
bandslook like
they can be wound tight from a central point at the
top.I am
wondering if they pre stress these significantly so that
there is less movementwhen they
are compressed at depth. 
Also I
commented on your retaining system when I first saw it, that
I thought thevertical
floatational force might move it upward, or the dome pivot
out from the bottom.Perhaps
you could exert more pressure on the dome with your clamping
system?
Alan

  From: Alec Smyth via
Personal_Submersibles
<personal_submersibles at psubs.org>

To: Personal
Submersibles General Discussion
<personal_submersibles at psubs.org> 

Sent: Tuesday,
July 7, 2015 12:31 PM
  Subject: Re:
[PSUBS-MAILIST] calculation

Does the
window seat have some sort of inside diameter edge? I would
think if it does not, then its pretty much guaranteed to
slip with or without grease - with grease being the quieter
less-terrifying option.
Best,
Alec

On Mon,
Jul 6, 2015 at 6:50 PM, hank pronk via Personal_Submersibles
<personal_submersibles at psubs.org>
wrote:

Sean,

Thank you for the input, I think I will just use weights
like Alan says.

I am making a fixture to simulate the EPDM gasket compressed
under my dome.  I want to test it with grease and
without.  I will squeeze the gasket in the fixture then
push the top plate sideways with a pusher bolt to see if the
gasket allows movement.  I want to make sure my dome can
expand and contract at depth.

Hank

--------------------------------------------

On Mon, 7/6/15, Sean T. Stevenson via Personal_Submersibles
<personal_submersibles at psubs.org>
wrote:

 Subject: Re: [PSUBS-MAILIST] calculation

 To: "Personal Submersibles General Discussion"
<personal_submersibles at psubs.org>

 Received: Monday, July 6, 2015, 9:08 AM

 Hank - the force developed is dependent on the

 stiffness of both the bolt material and of the specimen

 you're pushing on.  You can't necessarily
equate

 this directly to torque because of friction in the bolt

 threads and at the bolt end contact, and of course the

 elasticity of the bolt itself. You can only estimate
it. 

 There are many online tools for calculating the
developed

 tensile force in a bolted connection, for example, but
these

 consider only the bolt as the deformable element, and

 require an accurate estimate of coefficients of
friction,

 and this will change with lubrication. As you complicate
the

 system, it becomes more geometry dependent.

 A 1" - 8 UNC 2A thread is 8 threads per

 inch, so a set number of turns will give you the
approximate

 axial displacement (0.125" per revolution -
approximate

 because the bolt will change length under load). If you

 assume a rigid fixture, then your strain is equal to
the

 overall change in length (calculated from # of bolt
turns),

 divided by the gauge length (distance over which the
length

 change occurs, which would be the length of your
specimen

 measured between the rigid fixture and the end of your
jack

 bolt). Compressive or tensile load is then calculated
based

 on the modulus of elasticity of the specimen. 

 Alternatively, you can measure the load (make the bolt
or

 fixture into a load cell or strain gauge the specimen)
and

 calculate the material properties.

 Load, axial displacement, modulus. You need any

 two to calculate the third.

 What are you making / testing?

 Sean

 On July 6, 2015 6:26:49 AM

 MDT, hank pronk via Personal_Submersibles

 <personal_submersibles at psubs.org>
wrote:

 Hi all,

 I

 need help, can anyone tell me how to calculate how much

 force a bolt can push or pull using a torque wrench to
turn

 the bolt. So how many foot pounds of torque does it take
to

 rotate a bolt to  create 250 lbs push with a 1 in
coarse

 thread bolt.  I need to make a test fixture.

 Hank

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