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Re: Shear force of Graded bolts

To: Frank Marrone <marrone@wco.com>
Subject: Re: Shear force of Graded bolts
From: Steve Laifman <laifman@flash.net>
Date: Tue, 10 Feb 1998 17:09:46 +0000

Frank Marrone wrote:

> Does anyone have shear loading (not tensil) values for Grade5 and Grade8
> bolts.  I have heard that Grade8 bolts have less shear loading capacity
> than Grade5 bolts, is this true?
>
> Frank Marrone           MK I Tiger B9471116
> marrone@wco.com         '97 Crown Vic LX
>                         Yamaha Seca 900 (aka XJ900RK)
>                         '79 Spitfire
>                         '66 Ford LTD
>                         '88 Nissan 4WD p'up

Frank & Tigers,

I did some research on this issue (I asked one of my mechanical systems
staff members), and here is his reply:

"Steve:  It ain't true.  Data on SAE graded bolts is hard to find but
apparently, a grade 5 is equivalent to an ASTM A325 or A449[120 Kpsi], a
grade 8 is an A354 or A490[150 Kpsi].  Maximum recommended shear stress is
21 Kpsi and 28 Kpsi respectively, if the threads are in the shear plane,
and
30 Kpsi or 40 Kpsi if the full bolt diameter is in the shear plane[ a good
idea].

     Shear Stress = Force/ Area=Force/ Pi x  d square over 4 for the full
shank case.

     For threads: Area =(Pi/4) x (d-0.9743/n)Squared        n= number of
threads/inch[?]         d= nominal shank diameter

In structural applications, A325 and A490 bolts, by code, are limited to
one[1] torque cycle and have to be destroyed when removed.  I don't know if

the A449 and A354 bolts have the same restriction.  The SAE bolts
apparently
don't.

Hope this is helpful.  Try a good library for the ASTM Specs on
fasteners[section 15] or check Carroll Smith's book on fasteners for race
car construction."

Hope it helps,

Steve

--
Steve Laifman         < One first kiss,       >
B9472289              < one first love, and   >
                      < one first win, is all >
                      < you get in this life. >


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