Date:         Tue, 24 Apr 2001 23:18:46 -0400
Reply-To:     David Beierl <dbeierl@attglobal.net>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@attglobal.net>
Subject:      Re: 85 muffler question
Comments: To: Jean-Guy Savoie <jgsavoie@nbnet.nb.ca>
Comments: cc: CTONLINE@webtv.net
In-Reply-To:  <01eb01c0cd2a$ce726d60$0200000a@nbtel.net>
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At 09:55 PM 4/24/2001, Jean-Guy Savoie wrote:
>I don't know much about stress and strain relief on the rod ends (David:
>explain?) but I made mine out of an old canvas lawnchair frame.  So far (2

Terry pointed out to me the question of internal stress relief in the
metal, but I was talking about what happens when you go suddenly from
something stiff to something limber or vice versa.  If the transition is
too abrupt you tend to have things break at the transition point -- stress
(applied from outside) is concentrated there so that stress per unit area
is high.  That's why you have to skive the edges of a bicycle tire patch if
you want it to stay on the tube...an extreme example is a cracked
windshield.  The crack concentrates all the stress in the space of a
(relatively) few molecules, so you can make a crack spread right across
your windshield just by thumping with your fist from the other side.  The
VW-supplied struts have carefully formed ends that take about an inch to go
from all-round to all-flat.  They do it by flattening the edges and
gradually working into the center, leaving a profile sort of like a
sharpened pencil with the flattened area surrounding and extending it.

Just to keep the words straight, stress is the force applied and strain is
the resulting movement (if any).

Also, it would appear that the common terminology for what I'm talking
about is "strain relief" -- at least in the sense of an external device
such as would be used where a wire enters a piece of equipment, a headphone
plug and suchlike.  "Stress relief" is used to describe the relieving of
internal stresses in a piece of metal by annealing or other means.  I don't
know the standard usage for what I'm talking about.

david

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"