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Re: Load Indicating Washers.

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Seems to me that two washers in direct contact with one another would have
equal loads in them.  The washers will behave as springs.  The deflection
doubles but the load remains the same.

Gerry


At 12:34 AM 1/23/2002 +0000, you wrote:
Here is a lengthy summary of the Belleville washer and similar concept
washers that you might find interesting:

http://www.fastener-world.com.tw/new/Manag_contents_e/fw_colum/e_sc_fw69_03.htm

Of course, I've never used this site before, so take it for what it is
worth.  It sounds like stacking two *might* give you something like twice
the resistance if everything worked exactly right, like stacking two beams
without connecting them to one another, but there also seems to be a lot
that could go wrong.  If they bind and try to act compositely, you could
end up with too much load.  If they don't overlap exactly, you could start
to bend them one after the other, each would fail one after the other at
the same load, kind of like the CMU block analogy.  I might try this if I
was putting up something in my garage, and I don't really need the
intended load, but I wouldn't stake anything important on it.  Might be a
good time to find the right tool for the job, instead.  Good luck.

Regis


From: "Conrad Guymon" <conrad(--nospam--at)karren.com>
Reply-To: <seaint(--nospam--at)seaint.org>
To: <seaint(--nospam--at)seaint.org>
Subject: Re: Load Indicating Washers.
Date: Tue, 22 Jan 2002 15:19:31 -0700

I don't know what a Belleville washer is, so maybe I'm exposing my
ignorance.  It seems that if you stacked these washers, it could be
compared to stacking blocks.  Say one of them fails at  1699 lbs, the
other 1701 lbs.  You would load the stack to 1699 lbs, and one block
fails.  You add two more lbs, and the other block fails.  If you stack
them, it seems that you are only getting an indication of the weaker of
the two, not the sum of both.

Am I thinking this through right, or did I just expose my ignorance?

Would a Simpson PLI washer give you the values you need?  I can't find
values listed in the catalog I have, just pretty pictures.

Conrad Guymon, P.E.
  ----- Original Message -----
  From: vicpeng
  To: SEAINT
  Sent: Tuesday, January 22, 2002 2:08 PM
  Subject: Load Indicating Washers.


  I'm sure this topic was discussed in the past, however, a search of
the archives didn't find the answer.  I'll keep looking, it's possible
that my search query on "washers" & "DTI washers" is wrong.

  I need to clamp a bracket (to be used for a friction grip), and I need
a washer/other that will indicate when I have reached the clamping force.

  I have access to beveled (Belleville) washers that give a clamp force
of 2373 lb (max P = 3078 lb).  I need 3400 lb.  Would  putting 2 washers
of 1700 lb on one side give me the load I need.

  Methinks that it doesn't add that simply?

  Thor A Tandy P.Eng
  Victoria BC
  Canada
  e-mail: vicpeng(--nospam--at)sprint.ca


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