[PSUBS-MAILIST] calculation

[hank pronk via Personal_Submersibles]

Alec,
What is under your dome.
Hank--------------------------------------------
On Mon, 7/6/15, Alec Smyth 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, 8:31 PM
 
 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
 
 
 
  Personal_Submersibles mailing
 list
 
  Personal_Submersibles at psubs.org
 
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