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RE: Thread shear

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Per Fastener Design Manual by Barrett, NASA Ref Pub 1228:
 
P = (Pi * dm * Fs * L)*(1/3)
 
P = Pullout load, lb
dm = mean diameter of threaded hole, in.
Fs = material ult or yield shear stress
L = length of thread engagement, in.
The 1/3 factor is empirical and allows for a degree of mismatch.  If threads
were perfectly mated the factor would be 1/2.
 
Regards,
Harold Sprague
The Neenan Company 
 

-----Original Message-----
From: Robert Rollo [mailto:rrollo(--nospam--at)TEAM-PSC.com]
Sent: Monday, May 10, 1999 11:05 AM
To: seaint(--nospam--at)seaint.org; structx(--nospam--at)mLists.net
Subject: Thread shear



help ! 

what length of thread is required to develop the full tension of a grade 5
bolt (3/8" diam specifically). 
is this a simple rule of thumb or must one figure the total shear plane
area, etc etc? 

tia 

robert d. rollo, PE 
Corporate Associate 
Parkhill, Smith & Cooper, Inc. 
Lubbock, Texas 
rrollo(--nospam--at)team-psc.com 
rdrollo(--nospam--at)aol.com 
(806) 761-7539vox 
(806) 747-7146 fax