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Re: Stripping Treads

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There was a thread on this subject a while ago,  which BTW Harold answered   :)


FED-STD-H28 is a good reference but the easily accesable electronic copy was not very  readable

http://test.wbdg.org/ccb/FEDMIL/fed_h28.pdf#search=%22fed-std-h28%22

go to http://assist.daps.dla.mil/quicksearch/

& input FED-STD-H28 as the document ID.  The search will pull up various flavors of H28

here is a link to a site that does the calcs per FED-STD-H28 & Machinery's Handbook

http://www.engineersedge.com/thread_strength/thread_minimum_length_engagement_fed-std-h28.htm

cheers
Bob




On 10/2/06, Harold Sprague <spraguehope(--nospam--at)hotmail.com> wrote:
Prior to the NASA?

Goodier, "The Distribution of Load on the Threads of Screws", Journal of
Applied Mechanics, March 1940.

Regards,
Harold Sprague





>From: "Rich Lewis" <seaint04(--nospam--at)lewisengineering.com>
>Reply-To: < seaint(--nospam--at)seaint.org>
>To: <seaint(--nospam--at)seaint.org>
>Subject: RE: Stripping Treads
>Date: Mon, 2 Oct 2006 16:52:54 -0500
>
>Chuck,
>
>
>
>Yes, please do, since I can't find many other resources.
>
>
>
>Rich
>
>
>
>
>
>   _____
>
>From: chuck utzman [mailto: chuckuc(--nospam--at)pacbell.net]
>Sent: Friday, September 29, 2006 3:34 PM
>To: seaint(--nospam--at)seaint.org
>Subject: Re: Stripping Treads
>
>
>
>I could take a look in my Northrop Design Manual circa 1968  :o) is that
>prior enough?
>Chuck Utzman, P.E.
>
>Rich Lewis wrote:
>
>
>
>I'm looking for the design equation for stripping threads.  I have anchor
>bolts in tension and the bolt doesn't extend through the nut.  Now I have
>to
>sharpen a pencil and see if the design tensile force is less than what
>would
>strip what is left of the threads on the bolt.  If not then the contractor
>will need to weld an extension onto the bolts.
>
>
>
>I'm having a difficult time finding design literature on this.  AISC
>doesn't
>cover bolts.  Logic tells me it is the area of shear of the pitch diameter
>of the threads.  Since the pitch diameter occurs midway between the peaks
>and valleys, it would be ½ the perimeter area of the threaded section put
>in
>shear by the tension force on the nut/bolt.  I found a reference for a bolt
>guide in one of Harold S old posts to a 1998 NASA RP-1228 "Fastener Design
>Manual".  In this report they recommend using 1/3 the perimeter area of the
>pitch diameter to account for loose fit of the nut and bolt.  It makes
>sense
>to me.  The equation is P=(PI*DIA*Fs*L)/3 where DIA is the pitch diameter.
>It is written for yield strength and ultimate tensile strength.  I was
>going
>to input 0.6*Fy and 0.5*Fu to come up with allowable loads.
>
>
>
>I've been searching other books and haven't found any reference to analysis
>or design recommendations for stripping forces on a thread.  Surely there
>had to be some recommendations prior to the 1998 NASA report.  Can anyone
>give me other references to analysis and design of bolt thread stripping?
>
>
>
>Thanks.
>
>
>
>Rich
>
>
>

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