Is this application considered Single Shear or Double Shear?
Is this application considered Single Shear or Double Shear?
(OP)
I've been having a discussion with fellow work mates. I am trying to determine (in the picture below) if the pin is in Single or Double Shear based on the fact the center section is a square tube?

All comments and help are appreciated.
Thanks,
Pirate

All comments and help are appreciated.
Thanks,
Pirate





RE: Is this application considered Single Shear or Double Shear?
For me, double shear is more like a pin in a clevis.
another day in paradise, or is paradise one day closer ?
RE: Is this application considered Single Shear or Double Shear?
And I am sure that this one has quite a bit of deflection before anything actually shears.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Is this application considered Single Shear or Double Shear?
RE: Is this application considered Single Shear or Double Shear?
RE: Is this application considered Single Shear or Double Shear?
Mike McCann, PE, SE (WA)
RE: Is this application considered Single Shear or Double Shear?
RE: Is this application considered Single Shear or Double Shear?
I would call it double shear and not single shear because you have calculated one side of the pin shear stress based on 3500lb, if it were single shear then the full load of 7000lb would be acting on both halfs of the pin.
See this site http://www.roymech.co.uk/Useful_Tables/Screws/Bolt...
To call it single shear twice and do the calculation as in your post is double shear.
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Is this application considered Single Shear or Double Shear?
Yes.
For those saying "two instances of single shear", are you using a formula for single shear that outputs more stress than would be given by simply dividing the load by the cross-sectional area of the pin?
RE: Is this application considered Single Shear or Double Shear?
p.s. avoid putting the hole through the tube weld
RE: Is this application considered Single Shear or Double Shear?
your calc. are you saying your design is down ('cause 22222 > 16433) ? I don't think so. Your allowable stress (49ksi) looks like a shear stress, not a bearing stress. I think you're ok ('cause 11228 < 16433).
Is it just me or is this an "odd" way to preform the calc ? I'm used to calculating the MS form the allowable and the applied and seeing the FoS that falls out from that. I see the logic of requiring a FoS of 3, and so reducing your allowable ... just not what I'm used to.
another day in paradise, or is paradise one day closer ?
RE: Is this application considered Single Shear or Double Shear?
RE: Is this application considered Single Shear or Double Shear?
and on the loading assumption (conservative = uniform across the thickness, "sporty" = triangular, centroid at 1/3 thickness).
bending + shear interaction is, in my mind, somewhat nominal ... peak bending stress at zero shear stress, peak shear at zero bending ...
another day in paradise, or is paradise one day closer ?
RE: Is this application considered Single Shear or Double Shear?
From the link I gave earlier :-
Single shear is = 4*F/(pi*d^2)
Double shear = 2*F/(pi*d^2)
The difference between double and single shear if everything remains constant geometry wise is the force is effectively halfed.
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Is this application considered Single Shear or Double Shear?
The more meaningful distinction between "single shear" and "double shear" has to do with the how the fastener fits/bends within the members, how the fastener and nut/collar react moments, and the effect of eccentricity. These conditions affect the static strength to some degree and may affect the fatigue strength to a greater degree. In general, a double shear configuration usually has improved static/fatigue strengths (ASIDE from the simple effect of having two shear planes). Therefore, for typical configurations, you may compare the loads to two different sets of allowables.
Classifying it as two cases of "single shear" or a single case of "double shear" won't change the FBD loads, but there could be a tendency to directly jump to a scenario like the picture in the 4th post. But your case has no fastener head/nut on each end and there is no preload. Instead, you need an intermediate consideration based on judgement, test, or a safety factor to address the fact that you don't have a typical single shear case. In the end, it is better not to classify it at all (especially if fatigue is a concern). This could be misleading. That said, using single shear allowables would be better than double shear allwoables (though neither are actually correct).
Brian
www.espcomposites.com