Bolt Load and Joint Load
Bolt Load and Joint Load
(OP)
Hello everybody. I have been simulating a bolted joint connection in abaqus. I am trying to understand the load distribution between the joint and the bolt when an external compressive load is applied. I know that there is a formula
Fb= Fp-N*F
where Fb---bolt load
N--load factor
F--external applied load
I understand that when an external load(compressive on the members) is applied the bolt load relaxes than th pretension load and the joint load increases. But when my analysis results is showing me a decrease in both bolt load and the joint load. The shape of the joint is not flat-flat panel. The upper panel is a z-shape beam and the lower panel is a flat panle. I was wondering if this could happen or is there any otehr formula by wich i can calculate that factor(the portion of the external load which relaxes the bolt load). Thanks for your time and patience.
Kota
Fb= Fp-N*F
where Fb---bolt load
N--load factor
F--external applied load
I understand that when an external load(compressive on the members) is applied the bolt load relaxes than th pretension load and the joint load increases. But when my analysis results is showing me a decrease in both bolt load and the joint load. The shape of the joint is not flat-flat panel. The upper panel is a z-shape beam and the lower panel is a flat panle. I was wondering if this could happen or is there any otehr formula by wich i can calculate that factor(the portion of the external load which relaxes the bolt load). Thanks for your time and patience.
Kota





RE: Bolt Load and Joint Load
http://www.boltscience.com/pages/basics7.htm
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Bolt Load and Joint Load
RE: Bolt Load and Joint Load
have a reduction in clamping load.
Most forces produce a tension force
which increases the load on the
bolts.
RE: Bolt Load and Joint Load
RE: Bolt Load and Joint Load
sees the thermal load then it is
expanding and thus reducing the clamping
load of the bolt.
RE: Bolt Load and Joint Load
Kota
RE: Bolt Load and Joint Load
The problem is that the thermal loads
would normally expand something
and not contract it. Could you possibly
illustrate your application and just
explain how or where the thermal load
is coming from. If you looked at the
url that was provided earlier by CoryPad
the bolt is clamping two members. Would
this represent the two panels being clamped
together?
RE: Bolt Load and Joint Load
I am running a sequentially coupled analysis in Abaqus. First i get the temepertaure distribution for the bolted joint assembly and then i perform the mechanical analysis by constraining the model in the right way and apply the thermal load. And you said that the effect of temperature is to expand something. This happens only if the delta T is positive. And delta T can be negative if the temperature of the panel is lesser than the room temperature.
delta T= (t-sink temp)
Contraction= cte* delta T
where cte--- co-efficient of thermal expansion
for example if a particular node in the upper panel has 10 deg F and the sink temp is 7o deg F then the delta T would become -60 deg F and there would be a contraction and not expansion.
So considering this my model is experiencing a compression and hence the bolt load is decreasing. But the joint load is also decreasing which is very weird and I ma trying to figure out why the joint load is also decreasing when it is supposed to follow the reverse trend.Thanks
Kota
RE: Bolt Load and Joint Load
RE: Bolt Load and Joint Load
Seems to me if joint plates suffer a negative delta-T then contraction would occur, resulting in a lower clamping force. Is clamping force what you mean by 'joint load' ? Since the bolt is holding the joint together, when I was at school, I learnt that force = reaction, consequently both bolt load and joint load would decrease if delta T plate-to-sink is negative.