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Re: Load Indicating Washers.

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Yes and no.  Bellville washers are dished, and act as fairly linear
springs when flattened.  Placed in "parallel" with both dished facing the
same way will double the stiffness for the same deflection (thus,
doubling the load when flattened).  Placed in "series" with the dishes in
opposite directions, they will double the deflection for the same load,
thus cutting stiffness in half.  In the latter configuration, the total
load when fully flat is no change from one to two washers.

The manufacturer publishes and excellent catalogue with a nice technical
guide.  It may be on line now, but I haven't looked for a coupla years.

For the situation that Thor has, the first configuration would work very
well, just as suggested by Regis.


Russ Nester
rnester(--nospam--at)juno.com

**************************************

On Tue, 22 Jan 2002 18:38:04 -0800 Gerry Bader <gerry.bader(--nospam--at)verizon.net>
writes:
> 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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