Bolted Joint Separation
Bolted Joint Separation
(OP)
Hello,
I am running a static analysis on an assembly that has some bolted joints. In addition to the stresses in the parts I am interested in the forces in the preloaded bolts to make sure they are not overloaded. All the bolts have a fairly high safety factor and I am not overly concerned about them, however....
I was also asked to determine if there is joint separation between the bolted parts. Is it sufficient to look at the axial force in the bolt and assume that the joint will not separate from the load? The assumption is that because the bolts are not failing that the joints also must not be separating.
Is it that easy or I making some glaring error?
I believe that I need to be able to check the forces between the bolted parts but I'm not sure if there is a way to do that in the simulation. Maybe there is another way that you've used to check this? Run the analysis without preload and then compare forces in the bolt to the preloaded results?
Thanks,
I am running a static analysis on an assembly that has some bolted joints. In addition to the stresses in the parts I am interested in the forces in the preloaded bolts to make sure they are not overloaded. All the bolts have a fairly high safety factor and I am not overly concerned about them, however....
I was also asked to determine if there is joint separation between the bolted parts. Is it sufficient to look at the axial force in the bolt and assume that the joint will not separate from the load? The assumption is that because the bolts are not failing that the joints also must not be separating.
Is it that easy or I making some glaring error?
I believe that I need to be able to check the forces between the bolted parts but I'm not sure if there is a way to do that in the simulation. Maybe there is another way that you've used to check this? Run the analysis without preload and then compare forces in the bolt to the preloaded results?
Thanks,






RE: Bolted Joint Separation
TOP
CSWP, BSSE
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RE: Bolted Joint Separation
Solidworks calculates the stiffness ratios between the joints and the bolt. When you pull on the plate some of the force is transferred to the bolt (a function of the different stiffness ratios).
I can't just look at the axial force in the bolt and compare it to the preload force. If the parts are loaded it will be higher than the preload by some fraction of the force pulling it apart but that still doesn't tell me if the joint has separated.
Thanks
RE: Bolted Joint Separation
Generally the area under the bolt head is so much stiffer than the bolt that for all intents and purposes it is the part being clamped that unloads without the bolt seeing any appreciable change in tension until separation.
If a joint was designed so that the bolt saw appreciable/significant increase in tension after preloading and the bolt was tensioned to near yield any additional load might begin to fail the bolt or create serious fatigue issues. For example, a bolt on a hold down dog on a milling machine bed.
TOP
CSWP, BSSE
www.engtran.com www.niswug.org
www.linkedin.com/in/engineeringtransport
Phenom IIx6 1100T = 8GB = FX1400 = XP64SP2 = SW2009SP3
"Node news is good news."
RE: Bolted Joint Separation
Depending on preload & bolt strength you could theoretically separate the joint without failing the bolt. Depending on what you're joining that may or may not be a failure of the joint (but probably is).
RE: Bolted Joint Separation
RE: Bolted Joint Separation
thread1183-236375: Bolted Flange
My problem was that I wanted to manage the transition where the flange starts to separate, but the bolt holes still are clamped.