Shear force on torqued down bolts

[kingnero]

What is the influence of a certain torque towards the shear force in bolts, when the bolt needs to hold something in place; in such a manner that there is a shear force acting on the bolt as well as pure tension resulting from the torque.


I want to know how to check a certain force in an assembly, of which I don't know the name in english.
Dutch: "stuikspanning" => babelfish translation: butt force, which seems a rather questionable translation.
It is the force that stretches or shears thin plates in case of a too large force on a "single shear" or "double shear" connection (with eg. bolts or rivets).


How do I calculate the equivalent stress in the bolts (Von Mises, Huber & Hencky?) ?

and how will this result correlate to the max allowable "butt force" of the plates and the bolts ?

I hope I have explained my question good enough, if not please ask and I will try to explain further...

 

[hydtools]

It may be 'bearing' stress.
Try roymech here:

http://www.roymech.co.uk/Useful_Tables/Screws/Bolted_Joint.html

Ted

 

[hydtools]

A translation is upsetting pressure.
From this reference, it may be yield stress in English.

http://www.dralla.nl/mec/MEC1/Sheets/MCO-1B Les_3.pdf

Ted

 

[chris9]

If I were you I would look at shear stress in the threads (thread stripping) and work out preload due to applied torque. There are quite a few codes that cover stress analysis methods for bolts such as BS 2573 and BS 5950. Machinery's Handbook is one of the best reference books for bolt calculations. I wouldn't bother with von Mises stress, just look at thread shear and cross sectional shear to start with.

Chris

http://www.value-design-consulting.co.uk

 

[RolMec]

Hi kignero,

what you are looking for is maybe stress strain compression f.i. of polymer / plastic materials, ISO 3386 etc.. Cf. attached pdf, then check for the standards. // Can't upload, so in short: goto

http://www.c-bogmans.nl/producten.html,

page 1, point c): Standard for stuikspanning. Then google ISO 3386, f.i. with JSP. //

For bolt connection: Applied torque + given coeff. of friction (your application) makes up a tensional force in the bolt connection, check with relevant tables for your bolting system / bolting standard.
Allowable ssc --> Sorry, don't own those standards, hopefully you got that somewhere..

Regards

Roland

 

[CoryPad]

The von Mises stress is routinely used for combined tension and shear stresses during tightening (shear from applied tightening torque), and then during use (shear from forces applied to clamped joint members). VDI 2230 has calculation methods for bolted joints.

 

[kingnero]

Thanks for the replies.

I do not think Machinery's Handbook (I've got the 21st edition) is a good reference for bolt calculations,
Also I do not have VDI 2230 although it is on my wish list (as is Bickford's Handbook of bolts and bolted joints).


Is the maximum allowable shear stress the same for an unloaded bolt as well as for a bolt loaded in tension?


Assuming of course all other conditions are OK - shear stress in the threads, Bolt loaded in the elastic region (about 2/3 of proof stress), ...

 

[desertfox]

Hi kingnero

Can you please provide a sketch of your bolted joint or diagram showing the external loads the joint has to withstand, if so it might help us to help you and avoid us having to speculate.

desertfox

 

[hydtools]

See the thread about shear on a preloaded bolt in the Welding, Bonding and Fastener Engineering forum in Structural Engineers.

Conclusion: preload does not reduce shear capacity of the bolt.

Ted

 

[electricpete]

A list of references:

http://www.eng-tips.com/faqs.cfm?fid=600

In particular, a good detailed FREEreference for structural joints, which tend to be loaded in shear:

http://www.boltcouncil.org/files/2004RCSCSpecification.pdf

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[chris9]

I've got Machinery's Handbook 28th edition and use it all the time for bolt calculations. Maybe they have added more bolt stuff since the 21st edition?

Chris

http://www.value-design-consulting.co.uk