Fully tensioned bolts
Fully tensioned bolts
(OP)
Is it possible for a fully tensioned 1" A325 bolt to loosen under repetitive loading? It has always been my (and others) impression that it can not, but I am interested in what you guys know about this.
Also, are there any ill effects of tack welding the nut/bolt to eliminate the danger of loosening? My suspicion is that you may cause embrittlement in the bolt that could have a negative effect on fatigue resistance or strength.
Also, are there any ill effects of tack welding the nut/bolt to eliminate the danger of loosening? My suspicion is that you may cause embrittlement in the bolt that could have a negative effect on fatigue resistance or strength.






RE: Fully tensioned bolts
RE: Fully tensioned bolts
Do not welded quenched and tempered bolts (A325 or A490). These heat can create brittle fractures of the bolts.
Under fatigue loading additional safety factors are applied to avoid slip of the faying surfaces.
http://www.FerrellEngineering.com
RE: Fully tensioned bolts
The same force holding your slip-critical connection together (the tension on the bolt and thus the friction between the faying surfaces) is also holding the nut and bolt head against the outer surfaces of the plates. It's not going to just up and turn under normal repetitive loading.
If you exceed the slip capacity, you are now in bearing. If you have a thick filler between the main loadbearing plates, you'll get bending of the bolts. But there's still nothing there that would cause the plies of your connection to squish together and away from the nut or the bolt head.
Hg
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RE: Fully tensioned bolts
RE: Fully tensioned bolts
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Fully tensioned bolts
To prevent loosing provide a sufficient clamp force at the joint interface, to prevent movement between the bolt head or nut and the joint. Thread locking compounds (Loctite) have been shown effective in preventing loosening. If thread locking compound is used reduce lubricated torque loading (I have seen a common 20% reduction).
RE: Fully tensioned bolts
http://www.FerrellEngineering.com
RE: Fully tensioned bolts
A study was done of the high strength bolts in one of the rides at a "major theme park" near Orlando. Ultrasonic length measurements were taken before and after....elongation occurred with repetive loading.
Repeating what others have said...don't weld.
RE: Fully tensioned bolts
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Creep deformation can be from both the clamping force of the bolt and the service-load and coatings.
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